Adding upstream version 4.94.2.upstream/4.94.2upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

32 files changed, 7454 insertions, 0 deletions

diff --git a/src/auths/Makefile b/src/auths/Makefile
new file mode 100644
index 0000000..e85b22a
--- /dev/null
+++ b/src/auths/Makefile
@@ -0,0 +1,45 @@
+# Make file for building a library containing all the available authorization
+# methods, and calling it auths.a. In addition, there are functions that are
+# of general use in several methods; these are in separate modules so they are
+# linked in only when needed. This Makefile is called from the main make file,
+# after cd'ing to the auths subdirectory. When the relevant AUTH_ macros are
+# defined, the equivalent modules herein is not included in the final binary.
+
+OBJ = auth-spa.o call_pam.o call_pwcheck.o \
+      call_radius.o check_serv_cond.o cram_md5.o cyrus_sasl.o dovecot.o \
+      external.o get_data.o get_no64_data.o gsasl_exim.o heimdal_gssapi.o \
+      plaintext.o pwcheck.o \
+      spa.o tls.o xtextdecode.o xtextencode.o
+
+auths.a:         $(OBJ)
+		 @$(RM_COMMAND) -f auths.a
+		 @echo "$(AR) auths.a"
+		 $(FE)$(AR) auths.a $(OBJ)
+		 $(RANLIB) $@
+
+.SUFFIXES:       .o .c
+.c.o:;           @echo "$(CC) $*.c"
+		 $(FE)$(CC) -c $(CFLAGS) $(INCLUDE) $*.c
+
+auth-spa.o:         $(HDRS) auth-spa.c
+call_pam.o:         $(HDRS) call_pam.c
+call_pwcheck.o:     $(HDRS) call_pwcheck.c pwcheck.h
+call_radius.o:      $(HDRS) call_radius.c
+check_serv_cond.o:  $(HDRS) check_serv_cond.c
+get_data.o:         $(HDRS) get_data.c
+get_no64_data.o:    $(HDRS) get_no64_data.c
+pwcheck.o:          $(HDRS) pwcheck.c pwcheck.h
+xtextdecode.o:      $(HDRS) xtextdecode.c
+xtextencode.o:      $(HDRS) xtextencode.c
+
+cram_md5.o:         $(HDRS) cram_md5.c cram_md5.h
+cyrus_sasl.o:       $(HDRS) cyrus_sasl.c cyrus_sasl.h
+dovecot.o:          $(HDRS) dovecot.c dovecot.h
+external.o:         $(HDRS) external.c external.h
+gsasl_exim.o:       $(HDRS) gsasl_exim.c gsasl_exim.h
+heimdal_gssapi.o:   $(HDRS) heimdal_gssapi.c heimdal_gssapi.h
+plaintext.o:        $(HDRS) plaintext.c plaintext.h
+spa.o:              $(HDRS) spa.c spa.h
+tls.o:              $(HDRS) tls.c tls.h
+
+# End
diff --git a/src/auths/README b/src/auths/README
new file mode 100644
index 0000000..66bdcdc
--- /dev/null
+++ b/src/auths/README
@@ -0,0 +1,98 @@
+AUTHS
+
+The modules in this directory are in support of various authentication
+functions. Some of them, such as the base64 encoding/decoding and MD5
+computation, are just functions that might be used by several authentication
+mechanisms. Others are the SMTP AUTH mechanisms themselves, included in the
+final binary if the relevant AUTH_XXX value is set in Local/Makefile. The
+general functions are in separate modules so that they get included in the
+final binary only if they are actually called from somewhere.
+
+GENERAL FUNCTIONS
+
+The API for each of these functions is documented with the function's code.
+
+  auth_b64encode       encode in base 64
+  auth_b64decode       decode from base 64
+  auth_call_pam        do PAM authentication (if build with SUPPORT_PAM)
+  auth_get_data        issue SMTP AUTH challenge and read response
+  auth_xtextencode     encode as xtext
+  auth_xtextdecode     decode from xtext
+
+INTERFACE TO SMTP AUTHENTICATION MECHANISMS
+
+These are general SASL mechanisms, adapted for use with SMTP. Each
+authentication mechanism has three functions, for initialization, server
+authentication, and client authentication.
+
+INITIALIZATION
+
+The initialization function is called when the configuration is read, and can
+check for incomplete or illegal settings. It has one argument, a pointer to the
+instance block for this configured mechanism. It must set the flags called
+"server" and "client" in the generic auth_instance block to indicate whether
+the server and/or client functions are available for this authenticator.
+Typically this depends on whether server or client configuration options have
+been set, but it is also possible to have an authenticator that has only one of
+the server or client functions.  The function may not touch big_buffer.
+
+SERVER AUTHENTICATION
+
+The second function performs authentication as a server. It receives a pointer
+to the instance block, and its second argument is the remainder of the data
+from the AUTH command. The numeric variable maximum setting (expand_nmax) is
+set to zero, with $0 initialized as unset. The authenticator may set up numeric
+variables according to its (old) specification and $auth<n> variables the
+preferred ones nowadays; it should leave them set at the end so that they can
+be used for the expansion of the generic server_set_id option, which happens
+centrally.
+
+This function has access to the SMTP input and output so that it can write
+intermediate responses and read more data if necessary. There is a packaged
+function in auth_get_data() which outputs a challenge and reads a response.
+
+The yield of a server authentication check must be one of:
+
+  OK          success
+  DEFER       couldn't complete the check
+  FAIL        authentication failed
+  CANCELLED   authentication forced to fail by "*" response to challenge,
+                or by certain forced string expansion failures
+  BAD64       bad base64 data received
+  UNEXPECTED  unexpected data received
+
+In the case of DEFER, auth_defer_msg should point to an error message.
+
+CLIENT AUTHENTICATION
+
+The third function performs authentication as a client. It receives a pointer
+to the instance block, and four further arguments:
+
+  The smtp_context item for the connection to the remote host.
+
+  The normal command-reading timeout value.
+
+  A pointer to a buffer, to be used for receiving responses. It is done this
+    way so that the buffer is available for logging etc. in the calling
+    function in cases of error.
+
+  The size of the buffer.
+
+The yield of a client authentication check must be one of:
+
+  OK          success
+  FAIL_SEND   error after writing a command; errno is set
+  FAIL        failed after reading a response;
+              either errno is set (for timeouts, I/O failures) or
+              the buffer contains the SMTP response line
+  CANCELLED   the client cancelled authentication (often "fail" in expansion)
+              the buffer may contain a message; if not, *buffer = 0
+  ERROR       local problem (typically expansion error); message in buffer
+
+To communicate with the remote host the client should call
+smtp_write_command(). If this yields FALSE, the authenticator should return
+FAIL. After a successful write, the response is received by a call to
+smtp_read_response(), which should use the buffer handed to the client function
+as an argument.
+
+****
diff --git a/src/auths/auth-spa.c b/src/auths/auth-spa.c
new file mode 100644
index 0000000..44c99e9
--- /dev/null
+++ b/src/auths/auth-spa.c
@@ -0,0 +1,1524 @@
+/*************************************************
+*     Exim - an Internet mail transport agent    *
+*************************************************/
+
+/*
+ * This file provides the necessary methods for authenticating with
+ * Microsoft's Secure Password Authentication.
+
+ * All the original code used here was torn by Marc Prud'hommeaux out of the
+ * Samba project (by Andrew Tridgell, Jeremy Allison, and others).
+
+ * Tom Kistner provided additional code, adding spa_build_auth_challenge() to
+ * support server authentication mode.
+
+ * Mark Lyda provided a patch to solve this problem:
+
+ - Exim is indicating in its Authentication Request message (Type 1) that it
+   can transmit text in either Unicode or OEM format.
+
+ - Microsoft's SMTP server (smtp.email.msn.com) is responding in its
+   Challenge message (Type 2) that it will be expecting the OEM format.
+
+ - Exim does not pay attention to the text format requested by Microsoft's
+   SMTP server and, instead, defaults to using the Unicode format.
+
+ * References:
+ * http://www.innovation.ch/java/ntlm.html
+ * http://www.kuro5hin.org/story/2002/4/28/1436/66154
+
+ * It seems that some systems have existing but different definitions of some
+ * of the following types. I received a complaint about "int16" causing
+ * compilation problems. So I (PH) have renamed them all, to be on the safe
+ * side, by adding 'x' on the end.
+
+ * typedef signed short int16;
+ * typedef unsigned short uint16;
+ * typedef unsigned uint32;
+ * typedef unsigned char  uint8;
+
+ * The API is extremely simple:
+ * 1. Form a SPA authentication request based on the username
+ *    and (optional) domain
+ * 2. Send the request to the server and get an SPA challenge
+ * 3. Build the challenge response and send it back.
+ *
+ * Example usage is as
+ * follows:
+ *
+int main (int argc, char ** argv)
+{
+       SPAAuthRequest   request;
+       SPAAuthChallenge challenge;
+       SPAAuthResponse  response;
+       char msgbuf[2048];
+       char buffer[512];
+       char *username, *password, *domain, *challenge_str;
+
+       if (argc < 3)
+       {
+               printf ("Usage: %s <username> <password> [SPA Challenge]\n",
+                       argv [0]);
+               exit (1);
+       }
+
+       username = argv [1];
+       password = argv [2];
+       domain = 0;
+
+       spa_build_auth_request (&request, username, domain);
+
+       spa_bits_to_base64 (msgbuf, US &request,
+               spa_request_length(&request));
+
+       printf ("SPA Login request for username=%s:\n   %s\n",
+               argv [1], msgbuf);
+
+       if (argc < 4)
+       {
+               printf ("Run: %s <username> <password> [NTLM Challenge] " \
+                       "to complete authenitcation\n", argv [0]);
+               exit (0);
+       }
+
+       challenge_str = argv [3];
+
+       if (spa_base64_to_bits (CS &challenge, sizeof(challenge),
+                CCS (challenge_str))<0)
+       {
+                printf("bad base64 data in challenge: %s\n", challenge_str);
+                exit (1);
+       }
+
+       spa_build_auth_response (&challenge, &response, username, password);
+       spa_bits_to_base64 (msgbuf, US &response,
+               spa_request_length(&response));
+
+       printf ("SPA Response to challenge:\n   %s\n for " \
+               "username=%s, password=%s:\n   %s\n",
+               argv[3], argv [1], argv [2], msgbuf);
+       return 0;
+}
+ *
+ *
+ * All the client code used here was torn by Marc Prud'hommeaux out of the
+ * Samba project (by Andrew Tridgell, Jeremy Allison, and others).
+ * Previous comments are below:
+ */
+
+/*
+   Unix SMB/Netbios implementation.
+   Version 1.9.
+
+   a partial implementation of DES designed for use in the
+   SMB authentication protocol
+
+   Copyright (C) Andrew Tridgell 1998
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+*/
+
+
+/* NOTES:
+
+   This code makes no attempt to be fast! In fact, it is a very
+   slow implementation
+
+   This code is NOT a complete DES implementation. It implements only
+   the minimum necessary for SMB authentication, as used by all SMB
+   products (including every copy of Microsoft Windows95 ever sold)
+
+   In particular, it can only do a unchained forward DES pass. This
+   means it is not possible to use this code for encryption/decryption
+   of data, instead it is only useful as a "hash" algorithm.
+
+   There is no entry point into this code that allows normal DES operation.
+
+   I believe this means that this code does not come under ITAR
+   regulations but this is NOT a legal opinion. If you are concerned
+   about the applicability of ITAR regulations to this code then you
+   should confirm it for yourself (and maybe let me know if you come
+   up with a different answer to the one above)
+*/
+
+#define DEBUG_X(a,b) ;
+
+extern int DEBUGLEVEL;
+
+#include "../exim.h"
+#include "auth-spa.h"
+#include <assert.h>
+
+
+#ifndef _BYTEORDER_H
+# define _BYTEORDER_H
+
+# define RW_PCVAL(read,inbuf,outbuf,len) \
+       { if (read) { PCVAL (inbuf,0,outbuf,len); } \
+       else      { PSCVAL(inbuf,0,outbuf,len); } }
+
+# define RW_PIVAL(read,big_endian,inbuf,outbuf,len) \
+       { if (read) { if (big_endian) { RPIVAL(inbuf,0,outbuf,len); } else { PIVAL(inbuf,0,outbuf,len); } } \
+       else      { if (big_endian) { RPSIVAL(inbuf,0,outbuf,len); } else { PSIVAL(inbuf,0,outbuf,len); } } }
+
+# define RW_PSVAL(read,big_endian,inbuf,outbuf,len) \
+       { if (read) { if (big_endian) { RPSVAL(inbuf,0,outbuf,len); } else { PSVAL(inbuf,0,outbuf,len); } } \
+       else      { if (big_endian) { RPSSVAL(inbuf,0,outbuf,len); } else { PSSVAL(inbuf,0,outbuf,len); } } }
+
+# define RW_CVAL(read, inbuf, outbuf, offset) \
+       { if (read) { (outbuf) = CVAL (inbuf,offset); } \
+       else      { SCVAL(inbuf,offset,outbuf); } }
+
+# define RW_IVAL(read, big_endian, inbuf, outbuf, offset) \
+       { if (read) { (outbuf) = ((big_endian) ? RIVAL(inbuf,offset) : IVAL (inbuf,offset)); } \
+       else      { if (big_endian) { RSIVAL(inbuf,offset,outbuf); } else { SIVAL(inbuf,offset,outbuf); } } }
+
+# define RW_SVAL(read, big_endian, inbuf, outbuf, offset) \
+       { if (read) { (outbuf) = ((big_endian) ? RSVAL(inbuf,offset) : SVAL (inbuf,offset)); } \
+       else      { if (big_endian) { RSSVAL(inbuf,offset,outbuf); } else { SSVAL(inbuf,offset,outbuf); } } }
+
+# undef CAREFUL_ALIGNMENT
+
+/* we know that the 386 can handle misalignment and has the "right"
+   byteorder */
+# ifdef __i386__
+#  define CAREFUL_ALIGNMENT 0
+# endif
+
+# ifndef CAREFUL_ALIGNMENT
+#  define CAREFUL_ALIGNMENT 1
+# endif
+
+# define CVAL(buf,pos) ((US (buf))[pos])
+# define PVAL(buf,pos) ((unsigned)CVAL(buf,pos))
+# define SCVAL(buf,pos,val) (CVAL(buf,pos) = (val))
+
+
+# if CAREFUL_ALIGNMENT
+
+#  define SVAL(buf,pos) (PVAL(buf,pos)|PVAL(buf,(pos)+1)<<8)
+#  define IVAL(buf,pos) (SVAL(buf,pos)|SVAL(buf,(pos)+2)<<16)
+#  define SSVALX(buf,pos,val) (CVAL(buf,pos)=(val)&0xFF,CVAL(buf,pos+1)=(val)>>8)
+#  define SIVALX(buf,pos,val) (SSVALX(buf,pos,val&0xFFFF),SSVALX(buf,pos+2,val>>16))
+#  define SVALS(buf,pos) ((int16x)SVAL(buf,pos))
+#  define IVALS(buf,pos) ((int32x)IVAL(buf,pos))
+#  define SSVAL(buf,pos,val) SSVALX((buf),(pos),((uint16x)(val)))
+#  define SIVAL(buf,pos,val) SIVALX((buf),(pos),((uint32x)(val)))
+#  define SSVALS(buf,pos,val) SSVALX((buf),(pos),((int16x)(val)))
+#  define SIVALS(buf,pos,val) SIVALX((buf),(pos),((int32x)(val)))
+
+# else /* CAREFUL_ALIGNMENT */
+
+/* this handles things for architectures like the 386 that can handle
+   alignment errors */
+/*
+   WARNING: This section is dependent on the length of int16x and int32x
+   being correct
+*/
+
+/* get single value from an SMB buffer */
+#  define SVAL(buf,pos) (*(uint16x *)(CS (buf) + (pos)))
+#  define IVAL(buf,pos) (*(uint32x *)(CS (buf) + (pos)))
+#  define SVALS(buf,pos) (*(int16x *)(CS (buf) + (pos)))
+#  define IVALS(buf,pos) (*(int32x *)(CS (buf) + (pos)))
+
+/* store single value in an SMB buffer */
+#  define SSVAL(buf,pos,val) SVAL(buf,pos)=((uint16x)(val))
+#  define SIVAL(buf,pos,val) IVAL(buf,pos)=((uint32x)(val))
+#  define SSVALS(buf,pos,val) SVALS(buf,pos)=((int16x)(val))
+#  define SIVALS(buf,pos,val) IVALS(buf,pos)=((int32x)(val))
+
+# endif /* CAREFUL_ALIGNMENT */
+
+/* macros for reading / writing arrays */
+
+# define SMBMACRO(macro,buf,pos,val,len,size) \
+{ for (int l = 0; l < (len); l++) (val)[l] = macro((buf), (pos) + (size)*l); }
+
+# define SSMBMACRO(macro,buf,pos,val,len,size) \
+{ for (int l = 0; l < (len); l++) macro((buf), (pos) + (size)*l, (val)[l]); }
+
+/* reads multiple data from an SMB buffer */
+# define PCVAL(buf,pos,val,len) SMBMACRO(CVAL,buf,pos,val,len,1)
+# define PSVAL(buf,pos,val,len) SMBMACRO(SVAL,buf,pos,val,len,2)
+# define PIVAL(buf,pos,val,len) SMBMACRO(IVAL,buf,pos,val,len,4)
+# define PCVALS(buf,pos,val,len) SMBMACRO(CVALS,buf,pos,val,len,1)
+# define PSVALS(buf,pos,val,len) SMBMACRO(SVALS,buf,pos,val,len,2)
+# define PIVALS(buf,pos,val,len) SMBMACRO(IVALS,buf,pos,val,len,4)
+
+/* stores multiple data in an SMB buffer */
+# define PSCVAL(buf,pos,val,len) SSMBMACRO(SCVAL,buf,pos,val,len,1)
+# define PSSVAL(buf,pos,val,len) SSMBMACRO(SSVAL,buf,pos,val,len,2)
+# define PSIVAL(buf,pos,val,len) SSMBMACRO(SIVAL,buf,pos,val,len,4)
+# define PSCVALS(buf,pos,val,len) SSMBMACRO(SCVALS,buf,pos,val,len,1)
+# define PSSVALS(buf,pos,val,len) SSMBMACRO(SSVALS,buf,pos,val,len,2)
+# define PSIVALS(buf,pos,val,len) SSMBMACRO(SIVALS,buf,pos,val,len,4)
+
+
+/* now the reverse routines - these are used in nmb packets (mostly) */
+# define SREV(x) ((((x)&0xFF)<<8) | (((x)>>8)&0xFF))
+# define IREV(x) ((SREV(x)<<16) | (SREV((x)>>16)))
+
+# define RSVAL(buf,pos) SREV(SVAL(buf,pos))
+# define RSVALS(buf,pos) SREV(SVALS(buf,pos))
+# define RIVAL(buf,pos) IREV(IVAL(buf,pos))
+# define RIVALS(buf,pos) IREV(IVALS(buf,pos))
+# define RSSVAL(buf,pos,val) SSVAL(buf,pos,SREV(val))
+# define RSSVALS(buf,pos,val) SSVALS(buf,pos,SREV(val))
+# define RSIVAL(buf,pos,val) SIVAL(buf,pos,IREV(val))
+# define RSIVALS(buf,pos,val) SIVALS(buf,pos,IREV(val))
+
+/* reads multiple data from an SMB buffer (big-endian) */
+# define RPSVAL(buf,pos,val,len) SMBMACRO(RSVAL,buf,pos,val,len,2)
+# define RPIVAL(buf,pos,val,len) SMBMACRO(RIVAL,buf,pos,val,len,4)
+# define RPSVALS(buf,pos,val,len) SMBMACRO(RSVALS,buf,pos,val,len,2)
+# define RPIVALS(buf,pos,val,len) SMBMACRO(RIVALS,buf,pos,val,len,4)
+
+/* stores multiple data in an SMB buffer (big-endian) */
+# define RPSSVAL(buf,pos,val,len) SSMBMACRO(RSSVAL,buf,pos,val,len,2)
+# define RPSIVAL(buf,pos,val,len) SSMBMACRO(RSIVAL,buf,pos,val,len,4)
+# define RPSSVALS(buf,pos,val,len) SSMBMACRO(RSSVALS,buf,pos,val,len,2)
+# define RPSIVALS(buf,pos,val,len) SSMBMACRO(RSIVALS,buf,pos,val,len,4)
+
+# define DBG_RW_PCVAL(charmode,string,depth,base,read,inbuf,outbuf,len) \
+       { RW_PCVAL(read,inbuf,outbuf,len) \
+       DEBUG_X(5,("%s%04x %s: ", \
+             tab_depth(depth), base,string)); \
+    if (charmode) print_asc(5, US (outbuf), (len)); else \
+       for (int idx = 0; idx < len; idx++) { DEBUG_X(5,("%02x ", (outbuf)[idx])); } \
+       DEBUG_X(5,("\n")); }
+
+# define DBG_RW_PSVAL(charmode,string,depth,base,read,big_endian,inbuf,outbuf,len) \
+       { RW_PSVAL(read,big_endian,inbuf,outbuf,len) \
+       DEBUG_X(5,("%s%04x %s: ", \
+             tab_depth(depth), base,string)); \
+    if (charmode) print_asc(5, US (outbuf), 2*(len)); else \
+       for (int idx = 0; idx < len; idx++) { DEBUG_X(5,("%04x ", (outbuf)[idx])); } \
+       DEBUG_X(5,("\n")); }
+
+# define DBG_RW_PIVAL(charmode,string,depth,base,read,big_endian,inbuf,outbuf,len) \
+       { RW_PIVAL(read,big_endian,inbuf,outbuf,len) \
+       DEBUG_X(5,("%s%04x %s: ", \
+             tab_depth(depth), base,string)); \
+    if (charmode) print_asc(5, US (outbuf), 4*(len)); else \
+       for (int idx = 0; idx < len; idx++) { DEBUG_X(5,("%08x ", (outbuf)[idx])); } \
+       DEBUG_X(5,("\n")); }
+
+# define DBG_RW_CVAL(string,depth,base,read,inbuf,outbuf) \
+       { RW_CVAL(read,inbuf,outbuf,0) \
+       DEBUG_X(5,("%s%04x %s: %02x\n", \
+             tab_depth(depth), base, string, outbuf)); }
+
+# define DBG_RW_SVAL(string,depth,base,read,big_endian,inbuf,outbuf) \
+       { RW_SVAL(read,big_endian,inbuf,outbuf,0) \
+       DEBUG_X(5,("%s%04x %s: %04x\n", \
+             tab_depth(depth), base, string, outbuf)); }
+
+# define DBG_RW_IVAL(string,depth,base,read,big_endian,inbuf,outbuf) \
+       { RW_IVAL(read,big_endian,inbuf,outbuf,0) \
+       DEBUG_X(5,("%s%04x %s: %08x\n", \
+             tab_depth(depth), base, string, outbuf)); }
+
+#endif /* _BYTEORDER_H */
+
+void E_P16 (uschar *p14, uschar *p16);
+void E_P24 (uschar *p21, uschar *c8, uschar *p24);
+void D_P16 (uschar *p14, uschar *in, uschar *out);
+void SMBOWFencrypt (uschar passwd[16], uschar * c8, uschar p24[24]);
+
+void mdfour (uschar *out, uschar *in, int n);
+
+
+/*
+ * base64.c -- base-64 conversion routines.
+ *
+ * For license terms, see the file COPYING in this directory.
+ *
+ * This base 64 encoding is defined in RFC2045 section 6.8,
+ * "Base64 Content-Transfer-Encoding", but lines must not be broken in the
+ * scheme used here.
+ */
+
+static const char base64digits[] =
+  "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
+
+#define BAD    (char) -1
+static const char base64val[] = {
+  BAD, BAD, BAD, BAD, BAD, BAD, BAD, BAD, BAD, BAD, BAD, BAD, BAD, BAD, BAD,
+    BAD,
+  BAD, BAD, BAD, BAD, BAD, BAD, BAD, BAD, BAD, BAD, BAD, BAD, BAD, BAD, BAD,
+    BAD,
+  BAD, BAD, BAD, BAD, BAD, BAD, BAD, BAD, BAD, BAD, BAD, 62, BAD, BAD, BAD,
+    63,
+  52, 53, 54, 55, 56, 57, 58, 59, 60, 61, BAD, BAD, BAD, BAD, BAD, BAD,
+  BAD, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
+  15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, BAD, BAD, BAD, BAD, BAD,
+  BAD, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
+  41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, BAD, BAD, BAD, BAD, BAD
+};
+#define DECODE64(c)  (isascii(c) ? base64val[c] : BAD)
+
+void
+spa_bits_to_base64 (uschar *out, const uschar *in, int inlen)
+/* raw bytes in quasi-big-endian order to base 64 string (NUL-terminated) */
+{
+for (; inlen >= 3; inlen -= 3)
+  {
+  *out++ = base64digits[in[0] >> 2];
+  *out++ = base64digits[((in[0] << 4) & 0x30) | (in[1] >> 4)];
+  *out++ = base64digits[((in[1] << 2) & 0x3c) | (in[2] >> 6)];
+  *out++ = base64digits[in[2] & 0x3f];
+  in += 3;
+  }
+if (inlen > 0)
+  {
+  uschar fragment;
+
+  *out++ = base64digits[in[0] >> 2];
+  fragment = (in[0] << 4) & 0x30;
+  if (inlen > 1)
+     fragment |= in[1] >> 4;
+  *out++ = base64digits[fragment];
+  *out++ = (inlen < 2) ? '=' : base64digits[(in[1] << 2) & 0x3c];
+  *out++ = '=';
+  }
+*out = '\0';
+}
+
+
+/* The outlength parameter was added by PH, December 2004 */
+
+int
+spa_base64_to_bits (char *out, int outlength, const char *in)
+/* base 64 to raw bytes in quasi-big-endian order, returning count of bytes */
+{
+int len = 0;
+uschar digit1, digit2, digit3, digit4;
+
+if (in[0] == '+' && in[1] == ' ')
+  in += 2;
+if (*in == '\r')
+  return (0);
+
+do
+  {
+  if (len >= outlength)                   /* Added by PH */
+    return -1;                          /* Added by PH */
+  digit1 = in[0];
+  if (DECODE64 (digit1) == BAD)
+    return -1;
+  digit2 = in[1];
+  if (DECODE64 (digit2) == BAD)
+    return -1;
+  digit3 = in[2];
+  if (digit3 != '=' && DECODE64 (digit3) == BAD)
+    return -1;
+  digit4 = in[3];
+  if (digit4 != '=' && DECODE64 (digit4) == BAD)
+    return -1;
+  in += 4;
+  *out++ = (DECODE64 (digit1) << 2) | (DECODE64 (digit2) >> 4);
+  ++len;
+  if (digit3 != '=')
+    {
+    if (len >= outlength)                   /* Added by PH */
+      return -1;                          /* Added by PH */
+    *out++ =
+      ((DECODE64 (digit2) << 4) & 0xf0) | (DECODE64 (digit3) >> 2);
+    ++len;
+    if (digit4 != '=')
+      {
+      if (len >= outlength)                   /* Added by PH */
+	return -1;                          /* Added by PH */
+      *out++ = ((DECODE64 (digit3) << 6) & 0xc0) | DECODE64 (digit4);
+      ++len;
+      }
+    }
+  }
+while (*in && *in != '\r' && digit4 != '=');
+
+return len;
+}
+
+
+static uschar perm1[56] = { 57, 49, 41, 33, 25, 17, 9,
+  1, 58, 50, 42, 34, 26, 18,
+  10, 2, 59, 51, 43, 35, 27,
+  19, 11, 3, 60, 52, 44, 36,
+  63, 55, 47, 39, 31, 23, 15,
+  7, 62, 54, 46, 38, 30, 22,
+  14, 6, 61, 53, 45, 37, 29,
+  21, 13, 5, 28, 20, 12, 4
+};
+
+static uschar perm2[48] = { 14, 17, 11, 24, 1, 5,
+  3, 28, 15, 6, 21, 10,
+  23, 19, 12, 4, 26, 8,
+  16, 7, 27, 20, 13, 2,
+  41, 52, 31, 37, 47, 55,
+  30, 40, 51, 45, 33, 48,
+  44, 49, 39, 56, 34, 53,
+  46, 42, 50, 36, 29, 32
+};
+
+static uschar perm3[64] = { 58, 50, 42, 34, 26, 18, 10, 2,
+  60, 52, 44, 36, 28, 20, 12, 4,
+  62, 54, 46, 38, 30, 22, 14, 6,
+  64, 56, 48, 40, 32, 24, 16, 8,
+  57, 49, 41, 33, 25, 17, 9, 1,
+  59, 51, 43, 35, 27, 19, 11, 3,
+  61, 53, 45, 37, 29, 21, 13, 5,
+  63, 55, 47, 39, 31, 23, 15, 7
+};
+
+static uschar perm4[48] = { 32, 1, 2, 3, 4, 5,
+  4, 5, 6, 7, 8, 9,
+  8, 9, 10, 11, 12, 13,
+  12, 13, 14, 15, 16, 17,
+  16, 17, 18, 19, 20, 21,
+  20, 21, 22, 23, 24, 25,
+  24, 25, 26, 27, 28, 29,
+  28, 29, 30, 31, 32, 1
+};
+
+static uschar perm5[32] = { 16, 7, 20, 21,
+  29, 12, 28, 17,
+  1, 15, 23, 26,
+  5, 18, 31, 10,
+  2, 8, 24, 14,
+  32, 27, 3, 9,
+  19, 13, 30, 6,
+  22, 11, 4, 25
+};
+
+
+static uschar perm6[64] = { 40, 8, 48, 16, 56, 24, 64, 32,
+  39, 7, 47, 15, 55, 23, 63, 31,
+  38, 6, 46, 14, 54, 22, 62, 30,
+  37, 5, 45, 13, 53, 21, 61, 29,
+  36, 4, 44, 12, 52, 20, 60, 28,
+  35, 3, 43, 11, 51, 19, 59, 27,
+  34, 2, 42, 10, 50, 18, 58, 26,
+  33, 1, 41, 9, 49, 17, 57, 25
+};
+
+
+static uschar sc[16] = { 1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1 };
+
+static uschar sbox[8][4][16] = {
+  {{14, 4, 13, 1, 2, 15, 11, 8, 3, 10, 6, 12, 5, 9, 0, 7},
+   {0, 15, 7, 4, 14, 2, 13, 1, 10, 6, 12, 11, 9, 5, 3, 8},
+   {4, 1, 14, 8, 13, 6, 2, 11, 15, 12, 9, 7, 3, 10, 5, 0},
+   {15, 12, 8, 2, 4, 9, 1, 7, 5, 11, 3, 14, 10, 0, 6, 13}},
+
+  {{15, 1, 8, 14, 6, 11, 3, 4, 9, 7, 2, 13, 12, 0, 5, 10},
+   {3, 13, 4, 7, 15, 2, 8, 14, 12, 0, 1, 10, 6, 9, 11, 5},
+   {0, 14, 7, 11, 10, 4, 13, 1, 5, 8, 12, 6, 9, 3, 2, 15},
+   {13, 8, 10, 1, 3, 15, 4, 2, 11, 6, 7, 12, 0, 5, 14, 9}},
+
+  {{10, 0, 9, 14, 6, 3, 15, 5, 1, 13, 12, 7, 11, 4, 2, 8},
+   {13, 7, 0, 9, 3, 4, 6, 10, 2, 8, 5, 14, 12, 11, 15, 1},
+   {13, 6, 4, 9, 8, 15, 3, 0, 11, 1, 2, 12, 5, 10, 14, 7},
+   {1, 10, 13, 0, 6, 9, 8, 7, 4, 15, 14, 3, 11, 5, 2, 12}},
+
+  {{7, 13, 14, 3, 0, 6, 9, 10, 1, 2, 8, 5, 11, 12, 4, 15},
+   {13, 8, 11, 5, 6, 15, 0, 3, 4, 7, 2, 12, 1, 10, 14, 9},
+   {10, 6, 9, 0, 12, 11, 7, 13, 15, 1, 3, 14, 5, 2, 8, 4},
+   {3, 15, 0, 6, 10, 1, 13, 8, 9, 4, 5, 11, 12, 7, 2, 14}},
+
+  {{2, 12, 4, 1, 7, 10, 11, 6, 8, 5, 3, 15, 13, 0, 14, 9},
+   {14, 11, 2, 12, 4, 7, 13, 1, 5, 0, 15, 10, 3, 9, 8, 6},
+   {4, 2, 1, 11, 10, 13, 7, 8, 15, 9, 12, 5, 6, 3, 0, 14},
+   {11, 8, 12, 7, 1, 14, 2, 13, 6, 15, 0, 9, 10, 4, 5, 3}},
+
+  {{12, 1, 10, 15, 9, 2, 6, 8, 0, 13, 3, 4, 14, 7, 5, 11},
+   {10, 15, 4, 2, 7, 12, 9, 5, 6, 1, 13, 14, 0, 11, 3, 8},
+   {9, 14, 15, 5, 2, 8, 12, 3, 7, 0, 4, 10, 1, 13, 11, 6},
+   {4, 3, 2, 12, 9, 5, 15, 10, 11, 14, 1, 7, 6, 0, 8, 13}},
+
+  {{4, 11, 2, 14, 15, 0, 8, 13, 3, 12, 9, 7, 5, 10, 6, 1},
+   {13, 0, 11, 7, 4, 9, 1, 10, 14, 3, 5, 12, 2, 15, 8, 6},
+   {1, 4, 11, 13, 12, 3, 7, 14, 10, 15, 6, 8, 0, 5, 9, 2},
+   {6, 11, 13, 8, 1, 4, 10, 7, 9, 5, 0, 15, 14, 2, 3, 12}},
+
+  {{13, 2, 8, 4, 6, 15, 11, 1, 10, 9, 3, 14, 5, 0, 12, 7},
+   {1, 15, 13, 8, 10, 3, 7, 4, 12, 5, 6, 11, 0, 14, 9, 2},
+   {7, 11, 4, 1, 9, 12, 14, 2, 0, 6, 10, 13, 15, 3, 5, 8},
+   {2, 1, 14, 7, 4, 10, 8, 13, 15, 12, 9, 0, 3, 5, 6, 11}}
+};
+
+static void
+permute (char *out, char *in, uschar * p, int n)
+{
+for (int i = 0; i < n; i++)
+  out[i] = in[p[i] - 1];
+}
+
+static void
+lshift (char *d, int count, int n)
+{
+char out[64];
+for (int i = 0; i < n; i++)
+  out[i] = d[(i + count) % n];
+for (int i = 0; i < n; i++)
+  d[i] = out[i];
+}
+
+static void
+concat (char *out, char *in1, char *in2, int l1, int l2)
+{
+while (l1--)
+  *out++ = *in1++;
+while (l2--)
+  *out++ = *in2++;
+}
+
+static void
+xor (char *out, char *in1, char *in2, int n)
+{
+for (int i = 0; i < n; i++)
+  out[i] = in1[i] ^ in2[i];
+}
+
+static void
+dohash (char *out, char *in, char *key, int forw)
+{
+int i, j, k;
+char pk1[56];
+char c[28];
+char d[28];
+char cd[56];
+char ki[16][48];
+char pd1[64];
+char l[32], r[32];
+char rl[64];
+
+permute (pk1, key, perm1, 56);
+
+for (i = 0; i < 28; i++)
+  c[i] = pk1[i];
+for (i = 0; i < 28; i++)
+  d[i] = pk1[i + 28];
+
+for (i = 0; i < 16; i++)
+  {
+  lshift (c, sc[i], 28);
+  lshift (d, sc[i], 28);
+
+  concat (cd, c, d, 28, 28);
+  permute (ki[i], cd, perm2, 48);
+  }
+
+permute (pd1, in, perm3, 64);
+
+for (j = 0; j < 32; j++)
+  {
+  l[j] = pd1[j];
+  r[j] = pd1[j + 32];
+  }
+
+for (i = 0; i < 16; i++)
+  {
+  char er[48];
+  char erk[48];
+  char b[8][6];
+  char cb[32];
+  char pcb[32];
+  char r2[32];
+
+  permute (er, r, perm4, 48);
+
+  xor (erk, er, ki[forw ? i : 15 - i], 48);
+
+  for (j = 0; j < 8; j++)
+   for (k = 0; k < 6; k++)
+     b[j][k] = erk[j * 6 + k];
+
+  for (j = 0; j < 8; j++)
+   {
+   int m, n;
+   m = (b[j][0] << 1) | b[j][5];
+
+   n = (b[j][1] << 3) | (b[j][2] << 2) | (b[j][3] << 1) | b[j][4];
+
+   for (k = 0; k < 4; k++)
+     b[j][k] = (sbox[j][m][n] & (1 << (3 - k))) ? 1 : 0;
+   }
+
+  for (j = 0; j < 8; j++)
+   for (k = 0; k < 4; k++)
+     cb[j * 4 + k] = b[j][k];
+  permute (pcb, cb, perm5, 32);
+
+  xor (r2, l, pcb, 32);
+
+  for (j = 0; j < 32; j++)
+   l[j] = r[j];
+
+  for (j = 0; j < 32; j++)
+   r[j] = r2[j];
+  }
+
+concat (rl, r, l, 32, 32);
+
+permute (out, rl, perm6, 64);
+}
+
+static void
+str_to_key (uschar *str, uschar *key)
+{
+int i;
+
+key[0] = str[0] >> 1;
+key[1] = ((str[0] & 0x01) << 6) | (str[1] >> 2);
+key[2] = ((str[1] & 0x03) << 5) | (str[2] >> 3);
+key[3] = ((str[2] & 0x07) << 4) | (str[3] >> 4);
+key[4] = ((str[3] & 0x0F) << 3) | (str[4] >> 5);
+key[5] = ((str[4] & 0x1F) << 2) | (str[5] >> 6);
+key[6] = ((str[5] & 0x3F) << 1) | (str[6] >> 7);
+key[7] = str[6] & 0x7F;
+for (i = 0; i < 8; i++)
+    key[i] = (key[i] << 1);
+}
+
+
+static void
+smbhash (uschar *out, uschar *in, uschar *key, int forw)
+{
+int i;
+char outb[64];
+char inb[64];
+char keyb[64];
+uschar key2[8];
+
+str_to_key (key, key2);
+
+for (i = 0; i < 64; i++)
+  {
+  inb[i] = (in[i / 8] & (1 << (7 - (i % 8)))) ? 1 : 0;
+  keyb[i] = (key2[i / 8] & (1 << (7 - (i % 8)))) ? 1 : 0;
+  outb[i] = 0;
+  }
+
+dohash (outb, inb, keyb, forw);
+
+for (i = 0; i < 8; i++)
+  out[i] = 0;
+
+for (i = 0; i < 64; i++)
+  if (outb[i])
+   out[i / 8] |= (1 << (7 - (i % 8)));
+}
+
+void
+E_P16 (uschar *p14, uschar *p16)
+{
+uschar sp8[8] = { 0x4b, 0x47, 0x53, 0x21, 0x40, 0x23, 0x24, 0x25 };
+smbhash (p16, sp8, p14, 1);
+smbhash (p16 + 8, sp8, p14 + 7, 1);
+}
+
+void
+E_P24 (uschar *p21, uschar *c8, uschar *p24)
+{
+smbhash (p24, c8, p21, 1);
+smbhash (p24 + 8, c8, p21 + 7, 1);
+smbhash (p24 + 16, c8, p21 + 14, 1);
+}
+
+void
+D_P16 (uschar *p14, uschar *in, uschar *out)
+{
+smbhash (out, in, p14, 0);
+smbhash (out + 8, in + 8, p14 + 7, 0);
+}
+
+/****************************************************************************
+ Like strncpy but always null terminates. Make sure there is room!
+ The variable n should always be one less than the available size.
+****************************************************************************/
+
+char *
+StrnCpy (char *dest, const char *src, size_t n)
+{
+char *d = dest;
+if (!dest)
+  return (NULL);
+if (!src)
+  {
+  *dest = 0;
+  return (dest);
+  }
+while (n-- && (*d++ = *src++));
+*d = 0;
+return (dest);
+}
+
+size_t
+skip_multibyte_char (char c)
+{
+/* bogus if to get rid of unused compiler warning */
+if (c)
+  return 0;
+else
+  return 0;
+}
+
+
+/*******************************************************************
+safe string copy into a known length string. maxlength does not
+include the terminating zero.
+********************************************************************/
+
+char *
+safe_strcpy (char *dest, const char *src, size_t maxlength)
+{
+size_t len;
+
+if (!dest)
+  {
+  DEBUG_X (0, ("ERROR: NULL dest in safe_strcpy\n"));
+  return NULL;
+  }
+
+if (!src)
+  {
+  *dest = 0;
+  return dest;
+  }
+
+len = strlen (src);
+
+if (len > maxlength)
+  {
+  DEBUG_X (0, ("ERROR: string overflow by %d in safe_strcpy [%.50s]\n",
+	    (int) (len - maxlength), src));
+  len = maxlength;
+  }
+
+memcpy (dest, src, len);
+dest[len] = 0;
+return dest;
+}
+
+
+void
+strupper (char *s)
+{
+while (*s)
+  {
+   size_t skip = skip_multibyte_char (*s);
+   if (skip != 0)
+     s += skip;
+   else
+     {
+       if (islower ((uschar)(*s)))
+	 *s = toupper (*s);
+       s++;
+     }
+  }
+}
+
+
+/*
+ This implements the X/Open SMB password encryption
+ It takes a password, a 8 byte "crypt key" and puts 24 bytes of
+ encrypted password into p24
+ */
+
+void
+spa_smb_encrypt (uschar * passwd, uschar * c8, uschar * p24)
+{
+uschar p14[15], p21[21];
+
+memset (p21, '\0', 21);
+memset (p14, '\0', 14);
+StrnCpy (CS  p14, CS  passwd, 14);
+
+strupper (CS  p14);
+E_P16 (p14, p21);
+
+SMBOWFencrypt (p21, c8, p24);
+
+#ifdef DEBUG_PASSWORD
+DEBUG_X (100, ("spa_smb_encrypt: lm#, challenge, response\n"));
+dump_data (100, CS  p21, 16);
+dump_data (100, CS  c8, 8);
+dump_data (100, CS  p24, 24);
+#endif
+}
+
+/* Routines for Windows NT MD4 Hash functions. */
+static int
+_my_wcslen (int16x * str)
+{
+int len = 0;
+while (*str++ != 0)
+  len++;
+return len;
+}
+
+/*
+ * Convert a string into an NT UNICODE string.
+ * Note that regardless of processor type
+ * this must be in intel (little-endian)
+ * format.
+ */
+
+static int
+_my_mbstowcs (int16x * dst, uschar * src, int len)
+{
+int i;
+int16x val;
+
+for (i = 0; i < len; i++)
+  {
+  val = *src;
+  SSVAL (dst, 0, val);
+  dst++;
+  src++;
+  if (val == 0)
+   break;
+  }
+return i;
+}
+
+/*
+ * Creates the MD4 Hash of the users password in NT UNICODE.
+ */
+
+void
+E_md4hash (uschar * passwd, uschar * p16)
+{
+int len;
+int16x wpwd[129];
+
+/* Password cannot be longer than 128 characters */
+len = strlen (CS  passwd);
+if (len > 128)
+  len = 128;
+/* Password must be converted to NT unicode */
+_my_mbstowcs (wpwd, passwd, len);
+wpwd[len] = 0;               /* Ensure string is null terminated */
+/* Calculate length in bytes */
+len = _my_wcslen (wpwd) * sizeof (int16x);
+
+mdfour (p16, US wpwd, len);
+}
+
+/* Does both the NT and LM owfs of a user's password */
+void
+nt_lm_owf_gen (char *pwd, uschar nt_p16[16], uschar p16[16])
+{
+char passwd[130];
+
+memset (passwd, '\0', 130);
+safe_strcpy (passwd, pwd, sizeof (passwd) - 1);
+
+/* Calculate the MD4 hash (NT compatible) of the password */
+memset (nt_p16, '\0', 16);
+E_md4hash (US passwd, nt_p16);
+
+#ifdef DEBUG_PASSWORD
+DEBUG_X (100, ("nt_lm_owf_gen: pwd, nt#\n"));
+dump_data (120, passwd, strlen (passwd));
+dump_data (100, CS  nt_p16, 16);
+#endif
+
+/* Mangle the passwords into Lanman format */
+passwd[14] = '\0';
+strupper (passwd);
+
+/* Calculate the SMB (lanman) hash functions of the password */
+
+memset (p16, '\0', 16);
+E_P16 (US passwd, US p16);
+
+#ifdef DEBUG_PASSWORD
+DEBUG_X (100, ("nt_lm_owf_gen: pwd, lm#\n"));
+dump_data (120, passwd, strlen (passwd));
+dump_data (100, CS  p16, 16);
+#endif
+/* clear out local copy of user's password (just being paranoid). */
+memset (passwd, '\0', sizeof (passwd));
+}
+
+/* Does the des encryption from the NT or LM MD4 hash. */
+void
+SMBOWFencrypt (uschar passwd[16], uschar * c8, uschar p24[24])
+{
+uschar p21[21];
+
+memset (p21, '\0', 21);
+
+memcpy (p21, passwd, 16);
+E_P24 (p21, c8, p24);
+}
+
+/* Does the des encryption from the FIRST 8 BYTES of the NT or LM MD4 hash. */
+void
+NTLMSSPOWFencrypt (uschar passwd[8], uschar * ntlmchalresp, uschar p24[24])
+{
+uschar p21[21];
+
+memset (p21, '\0', 21);
+memcpy (p21, passwd, 8);
+memset (p21 + 8, 0xbd, 8);
+
+E_P24 (p21, ntlmchalresp, p24);
+#ifdef DEBUG_PASSWORD
+DEBUG_X (100, ("NTLMSSPOWFencrypt: p21, c8, p24\n"));
+dump_data (100, CS  p21, 21);
+dump_data (100, CS  ntlmchalresp, 8);
+dump_data (100, CS  p24, 24);
+#endif
+}
+
+
+/* Does the NT MD4 hash then des encryption. */
+
+void
+spa_smb_nt_encrypt (uschar * passwd, uschar * c8, uschar * p24)
+{
+uschar p21[21];
+
+memset (p21, '\0', 21);
+
+E_md4hash (passwd, p21);
+SMBOWFencrypt (p21, c8, p24);
+
+#ifdef DEBUG_PASSWORD
+DEBUG_X (100, ("spa_smb_nt_encrypt: nt#, challenge, response\n"));
+dump_data (100, CS  p21, 16);
+dump_data (100, CS  c8, 8);
+dump_data (100, CS  p24, 24);
+#endif
+}
+
+static uint32x A, B, C, D;
+
+static uint32x
+F (uint32x X, uint32x Y, uint32x Z)
+{
+return (X & Y) | ((~X) & Z);
+}
+
+static uint32x
+G (uint32x X, uint32x Y, uint32x Z)
+{
+return (X & Y) | (X & Z) | (Y & Z);
+}
+
+static uint32x
+H (uint32x X, uint32x Y, uint32x Z)
+{
+return X ^ Y ^ Z;
+}
+
+static uint32x
+lshift_a (uint32x x, int s)
+{
+x &= 0xFFFFFFFF;
+return ((x << s) & 0xFFFFFFFF) | (x >> (32 - s));
+}
+
+#define ROUND1(a,b,c,d,k,s) a = lshift_a(a + F(b,c,d) + X[k], s)
+#define ROUND2(a,b,c,d,k,s) a = lshift_a(a + G(b,c,d) + X[k] + (uint32x)0x5A827999,s)
+#define ROUND3(a,b,c,d,k,s) a = lshift_a(a + H(b,c,d) + X[k] + (uint32x)0x6ED9EBA1,s)
+
+/* this applies md4 to 64 byte chunks */
+static void
+spa_mdfour64 (uint32x * M)
+{
+int j;
+uint32x AA, BB, CC, DD;
+uint32x X[16];
+
+for (j = 0; j < 16; j++)
+  X[j] = M[j];
+
+AA = A;
+BB = B;
+CC = C;
+DD = D;
+
+ROUND1 (A, B, C, D, 0, 3);
+ROUND1 (D, A, B, C, 1, 7);
+ROUND1 (C, D, A, B, 2, 11);
+ROUND1 (B, C, D, A, 3, 19);
+ROUND1 (A, B, C, D, 4, 3);
+ROUND1 (D, A, B, C, 5, 7);
+ROUND1 (C, D, A, B, 6, 11);
+ROUND1 (B, C, D, A, 7, 19);
+ROUND1 (A, B, C, D, 8, 3);
+ROUND1 (D, A, B, C, 9, 7);
+ROUND1 (C, D, A, B, 10, 11);
+ROUND1 (B, C, D, A, 11, 19);
+ROUND1 (A, B, C, D, 12, 3);
+ROUND1 (D, A, B, C, 13, 7);
+ROUND1 (C, D, A, B, 14, 11);
+ROUND1 (B, C, D, A, 15, 19);
+
+ROUND2 (A, B, C, D, 0, 3);
+ROUND2 (D, A, B, C, 4, 5);
+ROUND2 (C, D, A, B, 8, 9);
+ROUND2 (B, C, D, A, 12, 13);
+ROUND2 (A, B, C, D, 1, 3);
+ROUND2 (D, A, B, C, 5, 5);
+ROUND2 (C, D, A, B, 9, 9);
+ROUND2 (B, C, D, A, 13, 13);
+ROUND2 (A, B, C, D, 2, 3);
+ROUND2 (D, A, B, C, 6, 5);
+ROUND2 (C, D, A, B, 10, 9);
+ROUND2 (B, C, D, A, 14, 13);
+ROUND2 (A, B, C, D, 3, 3);
+ROUND2 (D, A, B, C, 7, 5);
+ROUND2 (C, D, A, B, 11, 9);
+ROUND2 (B, C, D, A, 15, 13);
+
+ROUND3 (A, B, C, D, 0, 3);
+ROUND3 (D, A, B, C, 8, 9);
+ROUND3 (C, D, A, B, 4, 11);
+ROUND3 (B, C, D, A, 12, 15);
+ROUND3 (A, B, C, D, 2, 3);
+ROUND3 (D, A, B, C, 10, 9);
+ROUND3 (C, D, A, B, 6, 11);
+ROUND3 (B, C, D, A, 14, 15);
+ROUND3 (A, B, C, D, 1, 3);
+ROUND3 (D, A, B, C, 9, 9);
+ROUND3 (C, D, A, B, 5, 11);
+ROUND3 (B, C, D, A, 13, 15);
+ROUND3 (A, B, C, D, 3, 3);
+ROUND3 (D, A, B, C, 11, 9);
+ROUND3 (C, D, A, B, 7, 11);
+ROUND3 (B, C, D, A, 15, 15);
+
+A += AA;
+B += BB;
+C += CC;
+D += DD;
+
+A &= 0xFFFFFFFF;
+B &= 0xFFFFFFFF;
+C &= 0xFFFFFFFF;
+D &= 0xFFFFFFFF;
+
+for (j = 0; j < 16; j++)
+  X[j] = 0;
+}
+
+static void
+copy64 (uint32x * M, uschar *in)
+{
+int i;
+
+for (i = 0; i < 16; i++)
+  M[i] = (in[i * 4 + 3] << 24) | (in[i * 4 + 2] << 16) |
+    (in[i * 4 + 1] << 8) | (in[i * 4 + 0] << 0);
+}
+
+static void
+copy4 (uschar *out, uint32x x)
+{
+out[0] = x & 0xFF;
+out[1] = (x >> 8) & 0xFF;
+out[2] = (x >> 16) & 0xFF;
+out[3] = (x >> 24) & 0xFF;
+}
+
+/* produce a md4 message digest from data of length n bytes */
+void
+mdfour (uschar *out, uschar *in, int n)
+{
+uschar buf[128];
+uint32x M[16];
+uint32x b = n * 8;
+int i;
+
+A = 0x67452301;
+B = 0xefcdab89;
+C = 0x98badcfe;
+D = 0x10325476;
+
+while (n > 64)
+  {
+  copy64 (M, in);
+  spa_mdfour64 (M);
+  in += 64;
+  n -= 64;
+  }
+
+for (i = 0; i < 128; i++)
+  buf[i] = 0;
+memcpy (buf, in, n);
+buf[n] = 0x80;
+
+if (n <= 55)
+  {
+  copy4 (buf + 56, b);
+  copy64 (M, buf);
+  spa_mdfour64 (M);
+  }
+else
+  {
+  copy4 (buf + 120, b);
+  copy64 (M, buf);
+  spa_mdfour64 (M);
+  copy64 (M, buf + 64);
+  spa_mdfour64 (M);
+  }
+
+for (i = 0; i < 128; i++)
+  buf[i] = 0;
+copy64 (M, buf);
+
+copy4 (out, A);
+copy4 (out + 4, B);
+copy4 (out + 8, C);
+copy4 (out + 12, D);
+
+A = B = C = D = 0;
+}
+
+char versionString[] = "libntlm version 0.21";
+
+/* Utility routines that handle NTLM auth structures. */
+
+/* The [IS]VAL macros are to take care of byte order for non-Intel
+ * Machines -- I think this file is OK, but it hasn't been tested.
+ * The other files (the ones stolen from Samba) should be OK.
+ */
+
+
+/* I am not crazy about these macros -- they seem to have gotten
+ * a bit complex.  A new scheme for handling string/buffer fields
+ * in the structures probably needs to be designed
+ */
+
+#define spa_bytes_add(ptr, header, buf, count) \
+{ \
+if (buf && (count) != 0) /* we hate -Wint-in-bool-contex */ \
+  { \
+  SSVAL(&ptr->header.len,0,count); \
+  SSVAL(&ptr->header.maxlen,0,count); \
+  SIVAL(&ptr->header.offset,0,((ptr->buffer - ((uint8x*)ptr)) + ptr->bufIndex)); \
+  memcpy(ptr->buffer+ptr->bufIndex, buf, count); \
+  ptr->bufIndex += count; \
+  } \
+else \
+  { \
+  ptr->header.len = \
+  ptr->header.maxlen = 0; \
+  SIVAL(&ptr->header.offset,0,((ptr->buffer - ((uint8x*)ptr)) + ptr->bufIndex)); \
+  } \
+}
+
+#define spa_string_add(ptr, header, string) \
+{ \
+char *p = string; \
+int len = 0; \
+if (p) len = strlen(p); \
+spa_bytes_add(ptr, header, (US p), len); \
+}
+
+#define spa_unicode_add_string(ptr, header, string) \
+{ \
+char *p = string; \
+uschar *b = NULL; \
+int len = 0; \
+if (p) \
+  { \
+  len = strlen(p); \
+  b = strToUnicode(p); \
+  } \
+spa_bytes_add(ptr, header, b, len*2); \
+}
+
+
+#define GetUnicodeString(structPtr, header) \
+unicodeToString(((char*)structPtr) + IVAL(&structPtr->header.offset,0) , SVAL(&structPtr->header.len,0)/2)
+#define GetString(structPtr, header) \
+toString(((CS structPtr) + IVAL(&structPtr->header.offset,0)), SVAL(&structPtr->header.len,0))
+
+#ifdef notdef
+
+#define DumpBuffer(fp, structPtr, header) \
+dumpRaw(fp,(US structPtr)+IVAL(&structPtr->header.offset,0),SVAL(&structPtr->header.len,0))
+
+
+static void
+dumpRaw (FILE * fp, uschar *buf, size_t len)
+{
+int i;
+
+for (i = 0; i < len; ++i)
+  fprintf (fp, "%02x ", buf[i]);
+
+fprintf (fp, "\n");
+}
+
+#endif
+
+char *
+unicodeToString (char *p, size_t len)
+{
+int i;
+static char buf[1024];
+
+assert (len + 1 < sizeof buf);
+
+for (i = 0; i < len; ++i)
+  {
+  buf[i] = *p & 0x7f;
+  p += 2;
+  }
+
+buf[i] = '\0';
+return buf;
+}
+
+static uschar *
+strToUnicode (char *p)
+{
+static uschar buf[1024];
+size_t l = strlen (p);
+int i = 0;
+
+assert (l * 2 < sizeof buf);
+
+while (l--)
+  {
+  buf[i++] = *p++;
+  buf[i++] = 0;
+  }
+
+return buf;
+}
+
+static uschar *
+toString (char *p, size_t len)
+{
+static uschar buf[1024];
+
+assert (len + 1 < sizeof buf);
+
+memcpy (buf, p, len);
+buf[len] = 0;
+return buf;
+}
+
+#ifdef notdef
+
+void
+dumpSmbNtlmAuthRequest (FILE * fp, SPAAuthRequest * request)
+{
+fprintf (fp, "NTLM Request:\n");
+fprintf (fp, "      Ident = %s\n", request->ident);
+fprintf (fp, "      mType = %d\n", IVAL (&request->msgType, 0));
+fprintf (fp, "      Flags = %08x\n", IVAL (&request->flags, 0));
+fprintf (fp, "       User = %s\n", GetString (request, user));
+fprintf (fp, "     Domain = %s\n", GetString (request, domain));
+}
+
+void
+dumpSmbNtlmAuthChallenge (FILE * fp, SPAAuthChallenge * challenge)
+{
+fprintf (fp, "NTLM Challenge:\n");
+fprintf (fp, "      Ident = %s\n", challenge->ident);
+fprintf (fp, "      mType = %d\n", IVAL (&challenge->msgType, 0));
+fprintf (fp, "     Domain = %s\n", GetUnicodeString (challenge, uDomain));
+fprintf (fp, "      Flags = %08x\n", IVAL (&challenge->flags, 0));
+fprintf (fp, "  Challenge = ");
+dumpRaw (fp, challenge->challengeData, 8);
+}
+
+void
+dumpSmbNtlmAuthResponse (FILE * fp, SPAAuthResponse * response)
+{
+fprintf (fp, "NTLM Response:\n");
+fprintf (fp, "      Ident = %s\n", response->ident);
+fprintf (fp, "      mType = %d\n", IVAL (&response->msgType, 0));
+fprintf (fp, "     LmResp = ");
+DumpBuffer (fp, response, lmResponse);
+fprintf (fp, "     NTResp = ");
+DumpBuffer (fp, response, ntResponse);
+fprintf (fp, "     Domain = %s\n", GetUnicodeString (response, uDomain));
+fprintf (fp, "       User = %s\n", GetUnicodeString (response, uUser));
+fprintf (fp, "        Wks = %s\n", GetUnicodeString (response, uWks));
+fprintf (fp, "       sKey = ");
+DumpBuffer (fp, response, sessionKey);
+fprintf (fp, "      Flags = %08x\n", IVAL (&response->flags, 0));
+}
+#endif
+
+void
+spa_build_auth_request (SPAAuthRequest * request, char *user, char *domain)
+{
+char *u = strdup (user);
+char *p = strchr (u, '@');
+
+if (p)
+  {
+  if (!domain)
+   domain = p + 1;
+  *p = '\0';
+  }
+
+request->bufIndex = 0;
+memcpy (request->ident, "NTLMSSP\0\0\0", 8);
+SIVAL (&request->msgType, 0, 1);
+SIVAL (&request->flags, 0, 0x0000b207);      /* have to figure out what these mean */
+spa_string_add (request, user, u);
+spa_string_add (request, domain, domain);
+free (u);
+}
+
+
+
+void
+spa_build_auth_challenge (SPAAuthRequest * request, SPAAuthChallenge * challenge)
+{
+char chalstr[8];
+int i;
+int p = (int)getpid();
+int random_seed = (int)time(NULL) ^ ((p << 16) | p);
+
+request = request;  /* Added by PH to stop compilers whinging */
+
+/* Ensure challenge data is cleared, in case it isn't all used. This
+patch added by PH on suggestion of Russell King */
+
+memset(challenge, 0, sizeof(SPAAuthChallenge));
+
+challenge->bufIndex = 0;
+memcpy (challenge->ident, "NTLMSSP\0", 8);
+SIVAL (&challenge->msgType, 0, 2);
+SIVAL (&challenge->flags, 0, 0x00008201);
+SIVAL (&challenge->uDomain.len, 0, 0x0000);
+SIVAL (&challenge->uDomain.maxlen, 0, 0x0000);
+SIVAL (&challenge->uDomain.offset, 0, 0x00002800);
+
+/* generate eight pseudo random bytes (method ripped from host.c) */
+
+for(i=0;i<8;i++)
+  {
+  chalstr[i] = (uschar)(random_seed >> 16) % 256;
+  random_seed = (1103515245 - (chalstr[i])) * random_seed + 12345;
+  }
+
+memcpy(challenge->challengeData,chalstr,8);
+}
+
+
+
+
+/* This is the original source of this function, preserved here for reference.
+The new version below was re-organized by PH following a patch and some further
+suggestions from Mark Lyda to fix the problem that is described at the head of
+this module. At the same time, I removed the untidiness in the code below that
+involves the "d" and "domain" variables. */
+
+#ifdef NEVER
+void
+spa_build_auth_response (SPAAuthChallenge * challenge,
+                        SPAAuthResponse * response, char *user,
+                        char *password)
+{
+uint8x lmRespData[24];
+uint8x ntRespData[24];
+char *d = strdup (GetUnicodeString (challenge, uDomain));
+char *domain = d;
+char *u = strdup (user);
+char *p = strchr (u, '@');
+
+if (p)
+  {
+  domain = p + 1;
+  *p = '\0';
+  }
+
+spa_smb_encrypt (US password, challenge->challengeData, lmRespData);
+spa_smb_nt_encrypt (US password, challenge->challengeData, ntRespData);
+
+response->bufIndex = 0;
+memcpy (response->ident, "NTLMSSP\0\0\0", 8);
+SIVAL (&response->msgType, 0, 3);
+
+spa_bytes_add (response, lmResponse, lmRespData, 24);
+spa_bytes_add (response, ntResponse, ntRespData, 24);
+spa_unicode_add_string (response, uDomain, domain);
+spa_unicode_add_string (response, uUser, u);
+spa_unicode_add_string (response, uWks, u);
+spa_string_add (response, sessionKey, NULL);
+
+response->flags = challenge->flags;
+
+free (d);
+free (u);
+}
+#endif
+
+
+/* This is the re-organized version (see comments above) */
+
+void
+spa_build_auth_response (SPAAuthChallenge * challenge,
+                        SPAAuthResponse * response, char *user,
+                        char *password)
+{
+uint8x lmRespData[24];
+uint8x ntRespData[24];
+uint32x cf = IVAL(&challenge->flags, 0);
+char *u = strdup (user);
+char *p = strchr (u, '@');
+char *d = NULL;
+char *domain;
+
+if (p)
+  {
+  domain = p + 1;
+  *p = '\0';
+  }
+
+else domain = d = strdup((cf & 0x1)?
+  CCS GetUnicodeString(challenge, uDomain) :
+  CCS GetString(challenge, uDomain));
+
+spa_smb_encrypt (US password, challenge->challengeData, lmRespData);
+spa_smb_nt_encrypt (US password, challenge->challengeData, ntRespData);
+
+response->bufIndex = 0;
+memcpy (response->ident, "NTLMSSP\0\0\0", 8);
+SIVAL (&response->msgType, 0, 3);
+
+spa_bytes_add (response, lmResponse, lmRespData, (cf & 0x200) ? 24 : 0);
+spa_bytes_add (response, ntResponse, ntRespData, (cf & 0x8000) ? 24 : 0);
+
+if (cf & 0x1) {      /* Unicode Text */
+     spa_unicode_add_string (response, uDomain, domain);
+     spa_unicode_add_string (response, uUser, u);
+     spa_unicode_add_string (response, uWks, u);
+} else {             /* OEM Text */
+     spa_string_add (response, uDomain, domain);
+     spa_string_add (response, uUser, u);
+     spa_string_add (response, uWks, u);
+}
+
+spa_string_add (response, sessionKey, NULL);
+response->flags = challenge->flags;
+
+if (d != NULL) free (d);
+free (u);
+}
diff --git a/src/auths/auth-spa.h b/src/auths/auth-spa.h
new file mode 100644
index 0000000..cfe1b08
--- /dev/null
+++ b/src/auths/auth-spa.h
@@ -0,0 +1,92 @@
+/*************************************************
+*     Exim - an Internet mail transport agent    *
+*************************************************/
+
+/*
+ * This file provides the necessary methods for authenticating with
+ * Microsoft's Secure Password Authentication.
+
+ * All the code used here was torn by Marc Prud'hommeaux out of the
+ * Samba project (by Andrew Tridgell, Jeremy Allison, and others).
+ */
+
+/* December 2004: The spa_base64_to_bits() function has no length checking in
+it. I have added a check. PH */
+
+/* It seems that some systems have existing but different definitions of some
+of the following types. I received a complaint about "int16" causing
+compilation problems. So I (PH) have renamed them all, to be on the safe side.
+
+typedef signed short int16;
+typedef unsigned short uint16;
+typedef unsigned uint32;
+typedef unsigned char  uint8;
+*/
+
+typedef signed short int16x;
+typedef unsigned short uint16x;
+typedef unsigned uint32x;
+typedef unsigned char  uint8x;
+
+typedef struct
+{
+       uint16x         len;
+       uint16x         maxlen;
+       uint32x         offset;
+} SPAStrHeader;
+
+typedef struct
+{
+       char         ident[8];
+       uint32x         msgType;
+       SPAStrHeader    uDomain;
+       uint32x         flags;
+       uint8x         challengeData[8];
+       uint8x         reserved[8];
+       SPAStrHeader    emptyString;
+       uint8x         buffer[1024];
+       uint32x         bufIndex;
+} SPAAuthChallenge;
+
+
+typedef struct
+{
+       char         ident[8];
+       uint32x         msgType;
+       uint32x         flags;
+       SPAStrHeader    user;
+       SPAStrHeader    domain;
+       uint8x         buffer[1024];
+       uint32x         bufIndex;
+} SPAAuthRequest;
+
+typedef struct
+{
+       char         ident[8];
+       uint32x         msgType;
+       SPAStrHeader    lmResponse;
+       SPAStrHeader    ntResponse;
+       SPAStrHeader    uDomain;
+       SPAStrHeader    uUser;
+       SPAStrHeader    uWks;
+       SPAStrHeader    sessionKey;
+       uint32x         flags;
+       uint8x         buffer[1024];
+       uint32x         bufIndex;
+} SPAAuthResponse;
+
+#define spa_request_length(ptr) (((ptr)->buffer - (uint8x*)(ptr)) + (ptr)->bufIndex)
+
+void spa_bits_to_base64 (unsigned char *, const unsigned char *, int);
+int spa_base64_to_bits(char *, int, const char *);
+void spa_build_auth_response (SPAAuthChallenge *challenge,
+       SPAAuthResponse *response, char *user, char *password);
+void spa_build_auth_request (SPAAuthRequest *request, char *user,
+       char *domain);
+extern void spa_smb_encrypt (unsigned char * passwd, unsigned char * c8,
+                             unsigned char * p24);
+extern void spa_smb_nt_encrypt (unsigned char * passwd, unsigned char * c8,
+                                unsigned char * p24);
+extern char *unicodeToString(char *p, size_t len);
+extern void spa_build_auth_challenge(SPAAuthRequest *, SPAAuthChallenge *);
+
diff --git a/src/auths/call_pam.c b/src/auths/call_pam.c
new file mode 100644
index 0000000..80bb23e
--- /dev/null
+++ b/src/auths/call_pam.c
@@ -0,0 +1,204 @@
+/*************************************************
+*     Exim - an Internet mail transport agent    *
+*************************************************/
+
+/* Copyright (c) University of Cambridge 1995 - 2018 */
+/* Copyright (c) The Exim Maintainers 2020 */
+/* See the file NOTICE for conditions of use and distribution. */
+
+#include "../exim.h"
+
+/* This module contains functions that call the PAM authentication mechanism
+defined by Sun for Solaris and also available for Linux and other OS.
+
+We can't just compile this code and allow the library mechanism to omit the
+functions if they are not wanted, because we need to have the PAM headers
+available for compiling. Therefore, compile these functions only if SUPPORT_PAM
+is defined. However, some compilers don't like compiling empty modules, so keep
+them happy with a dummy when skipping the rest. Make it reference itself to
+stop picky compilers complaining that it is unused, and put in a dummy argument
+to stop even pickier compilers complaining about infinite loops.
+Then use a mutually-recursive pair as gcc is just getting stupid. */
+
+#ifndef SUPPORT_PAM
+static void dummy(int x);
+static void dummy2(int x) { dummy(x-1); }
+static void dummy(int x) { dummy2(x-1); }
+#else  /* SUPPORT_PAM */
+
+#ifdef PAM_H_IN_PAM
+#include <pam/pam_appl.h>
+#else
+#include <security/pam_appl.h>
+#endif
+
+/* According to the specification, it should be possible to have an application
+data pointer passed to the conversation function. However, I was unable to get
+this to work on Solaris 2.6, so static variables are used instead. */
+
+static int pam_conv_had_error;
+static const uschar *pam_args;
+static BOOL pam_arg_ended;
+
+
+
+/*************************************************
+*           PAM conversation function            *
+*************************************************/
+
+/* This function is passed to the PAM authentication function, and it calls it
+back when it wants data from the client. The string list is in pam_args. When
+we reach the end, we pass back an empty string once. If this function is called
+again, it will give an error response. This is protection against something
+crazy happening.
+
+Arguments:
+  num_msg        number of messages associated with the call
+  msg            points to an array of length num_msg of pam_message structures
+  resp           set to point to the response block, which has to be got by
+                   this function
+  appdata_ptr    the application data pointer - not used because in Solaris
+                   2.6 it always arrived in pam_converse() as NULL
+
+Returns:         a PAM return code
+*/
+
+static int
+pam_converse (int num_msg, PAM_CONVERSE_ARG2_TYPE **msg,
+  struct pam_response **resp, void *appdata_ptr)
+{
+int sep = 0;
+struct pam_response *reply;
+
+/* It seems that PAM frees reply[] */
+
+if (  pam_arg_ended
+   || !(reply = malloc(sizeof(struct pam_response) * num_msg)))
+  return PAM_CONV_ERR;
+
+for (int i = 0; i < num_msg; i++)
+  {
+  uschar *arg;
+  switch (msg[i]->msg_style)
+    {
+    case PAM_PROMPT_ECHO_ON:
+    case PAM_PROMPT_ECHO_OFF:
+      if (!(arg = string_nextinlist(&pam_args, &sep, NULL, 0)))
+	{
+	arg = US"";
+	pam_arg_ended = TRUE;
+	}
+      reply[i].resp = CS string_copy_malloc(arg); /* PAM frees resp */
+      reply[i].resp_retcode = PAM_SUCCESS;
+      break;
+
+    case PAM_TEXT_INFO:    /* Just acknowledge messages */
+    case PAM_ERROR_MSG:
+      reply[i].resp_retcode = PAM_SUCCESS;
+      reply[i].resp = NULL;
+      break;
+
+    default:  /* Must be an error of some sort... */
+      free(reply);
+      pam_conv_had_error = TRUE;
+      return PAM_CONV_ERR;
+    }
+  }
+
+*resp = reply;
+return PAM_SUCCESS;
+}
+
+
+
+/*************************************************
+*              Perform PAM authentication        *
+*************************************************/
+
+/* This function calls the PAM authentication mechanism, passing over one or
+more data strings.
+
+Arguments:
+  s        a colon-separated list of strings
+  errptr   where to point an error message
+
+Returns:   OK if authentication succeeded
+           FAIL if authentication failed
+           ERROR some other error condition
+*/
+
+int
+auth_call_pam(const uschar *s, uschar **errptr)
+{
+pam_handle_t *pamh = NULL;
+struct pam_conv pamc;
+int pam_error;
+int sep = 0;
+uschar *user;
+
+/* Set up the input data structure: the address of the conversation function,
+and a pointer to application data, which we don't use because I couldn't get it
+to work under Solaris 2.6 - it always arrived in pam_converse() as NULL. */
+
+pamc.conv = pam_converse;
+pamc.appdata_ptr = NULL;
+
+/* Initialize the static data - the current input data, the error flag, and the
+flag for data end. */
+
+pam_args = s;
+pam_conv_had_error = FALSE;
+pam_arg_ended = FALSE;
+
+/* The first string in the list is the user. If this is an empty string, we
+fail. PAM doesn't support authentication with an empty user (it prompts for it,
+causing a potential mis-interpretation). */
+
+user = string_nextinlist(&pam_args, &sep, NULL, 0);
+if (user == NULL || user[0] == 0) return FAIL;
+
+/* Start off PAM interaction */
+
+DEBUG(D_auth)
+  debug_printf("Running PAM authentication for user \"%s\"\n", user);
+
+pam_error = pam_start ("exim", CS user, &pamc, &pamh);
+
+/* Do the authentication - the pam_authenticate() will call pam_converse() to
+get the data it wants. After successful authentication we call pam_acct_mgmt()
+to apply any other restrictions (e.g. only some times of day). */
+
+if (pam_error == PAM_SUCCESS)
+  {
+  pam_error = pam_authenticate (pamh, PAM_SILENT);
+  if (pam_error == PAM_SUCCESS && !pam_conv_had_error)
+    pam_error = pam_acct_mgmt (pamh, PAM_SILENT);
+  }
+
+/* Finish the PAM interaction - this causes it to clean up store etc. Unclear
+what should be passed as the second argument. */
+
+pam_end(pamh, PAM_SUCCESS);
+
+/* Sort out the return code. If not success, set the error message. */
+
+if (pam_error == PAM_SUCCESS)
+  {
+  DEBUG(D_auth) debug_printf("PAM success\n");
+  return OK;
+  }
+
+*errptr = US pam_strerror(pamh, pam_error);
+DEBUG(D_auth) debug_printf("PAM error: %s\n", *errptr);
+
+if (pam_error == PAM_USER_UNKNOWN ||
+    pam_error == PAM_AUTH_ERR ||
+    pam_error == PAM_ACCT_EXPIRED)
+  return FAIL;
+
+return ERROR;
+}
+
+#endif  /* SUPPORT_PAM */
+
+/* End of call_pam.c */
diff --git a/src/auths/call_pwcheck.c b/src/auths/call_pwcheck.c
new file mode 100644
index 0000000..0adde44
--- /dev/null
+++ b/src/auths/call_pwcheck.c
@@ -0,0 +1,121 @@
+/*************************************************
+*     Exim - an Internet mail transport agent    *
+*************************************************/
+
+/* Copyright (c) University of Cambridge 1995 - 2015 */
+/* Copyright (c) The Exim Maintainers 2020 */
+/* See the file NOTICE for conditions of use and distribution. */
+
+/* This module contains interface functions to the two Cyrus authentication
+daemons. The original one was "pwcheck", which gives its name to the source
+file. This is now deprecated in favour of "saslauthd". */
+
+
+#include "../exim.h"
+#include "pwcheck.h"
+
+
+/*************************************************
+*      External entry point for pwcheck          *
+*************************************************/
+
+/* This function calls the now-deprecated "pwcheck" Cyrus-SASL authentication
+daemon, passing over a colon-separated user name and password. As this is
+called from the string expander, the string will always be in dynamic store and
+can be overwritten.
+
+Arguments:
+  s        a colon-separated username:password string
+  errptr   where to point an error message
+
+Returns:   OK if authentication succeeded
+           FAIL if authentication failed
+           ERROR some other error condition
+*/
+
+int
+auth_call_pwcheck(uschar *s, uschar **errptr)
+{
+uschar *reply = NULL;
+uschar *pw = Ustrrchr(s, ':');
+
+if (pw == NULL)
+  {
+  *errptr = US"pwcheck: malformed input - missing colon";
+  return ERROR;
+  }
+
+*pw++ = 0;   /* Separate user and password */
+
+DEBUG(D_auth)
+  debug_printf("Running pwcheck authentication for user \"%s\"\n", s);
+
+switch (pwcheck_verify_password(CS s, CS pw, CCSS &reply))
+  {
+  case PWCHECK_OK:
+  DEBUG(D_auth) debug_printf("pwcheck: success (%s)\n", reply);
+  return OK;
+
+  case PWCHECK_NO:
+  DEBUG(D_auth) debug_printf("pwcheck: access denied (%s)\n", reply);
+  return FAIL;
+
+  default:
+  DEBUG(D_auth) debug_printf("pwcheck: query failed (%s)\n", reply);
+  *errptr = reply;
+  return ERROR;
+  }
+}
+
+
+/*************************************************
+*       External entry point for pwauthd         *
+*************************************************/
+
+/* This function calls the "saslauthd" Cyrus-SASL authentication daemon,
+saslauthd, As this is called from the string expander, all the strings will
+always be in dynamic store and can be overwritten.
+
+Arguments:
+  username        username
+  password        password
+  service         optional service
+  realm           optional realm
+  errptr          where to point an error message
+
+Returns:   OK if authentication succeeded
+           FAIL if authentication failed
+           ERROR some other error condition
+*/
+
+int
+auth_call_saslauthd(const uschar *username, const uschar *password,
+  const uschar *service, const uschar *realm, uschar **errptr)
+{
+uschar *reply = NULL;
+
+if (service == NULL) service = US"";
+if (realm == NULL) realm = US"";
+
+DEBUG(D_auth)
+  debug_printf("Running saslauthd authentication for user \"%s\" \n", username);
+
+switch (saslauthd_verify_password(username, password, service,
+        realm, (const uschar **)(&reply)))
+  {
+  case PWCHECK_OK:
+  DEBUG(D_auth) debug_printf("saslauthd: success (%s)\n", reply);
+  return OK;
+
+  case PWCHECK_NO:
+  DEBUG(D_auth) debug_printf("saslauthd: access denied (%s)\n", reply);
+  return FAIL;
+
+  default:
+  DEBUG(D_auth) debug_printf("saslauthd: query failed (%s)\n", reply);
+  *errptr = reply;
+  return ERROR;
+  }
+}
+
+/* End of call_pwcheck.c */
diff --git a/src/auths/call_radius.c b/src/auths/call_radius.c
new file mode 100644
index 0000000..9d10b34
--- /dev/null
+++ b/src/auths/call_radius.c
@@ -0,0 +1,232 @@
+/*************************************************
+*     Exim - an Internet mail transport agent    *
+*************************************************/
+
+/* Copyright (c) The Exim Maintainers 2020 */
+/* Copyright (c) University of Cambridge 1995 - 2016 */
+/* See the file NOTICE for conditions of use and distribution. */
+
+/* This file was originally supplied by Ian Kirk. The libradius support came
+from Alex Kiernan. */
+
+/* ugly hack to work around redefinition of ENV by radiusclient.h and
+ * db.h: define _DB_H_ so the db.h include thinks it's already included,
+ * we can get away with it like this, since this file doesn't use any db
+ * functions. */
+#ifndef _DB_H_
+# define _DB_H_ 1
+# define _DB_EXT_PROT_IN_ 1
+# define DB void
+#endif
+
+#include "../exim.h"
+
+/* This module contains functions that call the Radius authentication
+mechanism.
+
+We can't just compile this code and allow the library mechanism to omit the
+functions if they are not wanted, because we need to have the Radius headers
+available for compiling. Therefore, compile these functions only if
+RADIUS_CONFIG_FILE is defined. However, some compilers don't like compiling
+empty modules, so keep them happy with a dummy when skipping the rest. Make it
+reference itself to stop picky compilers complaining that it is unused, and put
+in a dummy argument to stop even pickier compilers complaining about infinite
+loops. Then use a mutually-recursive pair as gcc is just getting stupid. */
+
+#ifndef RADIUS_CONFIG_FILE
+static void dummy(int x);
+static void dummy2(int x) { dummy(x-1); }
+static void dummy(int x) { dummy2(x-1); }
+#else  /* RADIUS_CONFIG_FILE */
+
+
+/* Two different Radius libraries are supported. The default is radiusclient,
+using its original API. At release 0.4.0 the API changed. */
+
+#ifdef RADIUS_LIB_RADLIB
+  #include <radlib.h>
+#else
+  #if !defined(RADIUS_LIB_RADIUSCLIENT) && !defined(RADIUS_LIB_RADIUSCLIENTNEW)
+  # define RADIUS_LIB_RADIUSCLIENT
+  #endif
+
+  #ifdef RADIUS_LIB_RADIUSCLIENTNEW
+  # include <freeradius-client.h>
+  #else
+  # include <radiusclient.h>
+  #endif
+#endif
+
+
+
+/*************************************************
+*              Perform RADIUS authentication     *
+*************************************************/
+
+/* This function calls the Radius authentication mechanism, passing over one or
+more data strings.
+
+Arguments:
+  s        a colon-separated list of strings
+  errptr   where to point an error message
+
+Returns:   OK if authentication succeeded
+           FAIL if authentication failed
+           ERROR some other error condition
+*/
+
+int
+auth_call_radius(const uschar *s, uschar **errptr)
+{
+uschar *user;
+const uschar *radius_args = s;
+int result;
+int sep = 0;
+
+#ifdef RADIUS_LIB_RADLIB
+  struct rad_handle *h;
+#else
+  #ifdef RADIUS_LIB_RADIUSCLIENTNEW
+    rc_handle *h;
+  #endif
+  VALUE_PAIR *send = NULL;
+  VALUE_PAIR *received;
+  unsigned int service = PW_AUTHENTICATE_ONLY;
+  char msg[4096];
+#endif
+
+
+if (!(user = string_nextinlist(&radius_args, &sep, NULL, 0))) user = US"";
+
+DEBUG(D_auth) debug_printf("Running RADIUS authentication for user \"%s\" "
+               "and \"%s\"\n", user, radius_args);
+
+*errptr = NULL;
+
+
+/* Authenticate using the radiusclient library */
+
+#ifndef RADIUS_LIB_RADLIB
+
+rc_openlog("exim");
+
+#ifdef RADIUS_LIB_RADIUSCLIENT
+if (rc_read_config(RADIUS_CONFIG_FILE) != 0)
+  *errptr = string_sprintf("RADIUS: can't open %s", RADIUS_CONFIG_FILE);
+
+else if (rc_read_dictionary(rc_conf_str("dictionary")) != 0)
+  *errptr = US"RADIUS: can't read dictionary";
+
+else if (!rc_avpair_add(&send, PW_USER_NAME, user, 0))
+  *errptr = US"RADIUS: add user name failed";
+
+else if (!rc_avpair_add(&send, PW_USER_PASSWORD, CS radius_args, 0))
+  *errptr = US"RADIUS: add password failed");
+
+else if (!rc_avpair_add(&send, PW_SERVICE_TYPE, &service, 0))
+  *errptr = US"RADIUS: add service type failed";
+
+#else  /* RADIUS_LIB_RADIUSCLIENT unset => RADIUS_LIB_RADIUSCLIENT2 */
+
+if (!(h = rc_read_config(RADIUS_CONFIG_FILE)))
+  *errptr = string_sprintf("RADIUS: can't open %s", RADIUS_CONFIG_FILE);
+
+else if (rc_read_dictionary(h, rc_conf_str(h, "dictionary")) != 0)
+  *errptr = US"RADIUS: can't read dictionary";
+
+else if (!rc_avpair_add(h, &send, PW_USER_NAME, user, Ustrlen(user), 0))
+  *errptr = US"RADIUS: add user name failed";
+
+else if (!rc_avpair_add(h, &send, PW_USER_PASSWORD, CS radius_args,
+    Ustrlen(radius_args), 0))
+  *errptr = US"RADIUS: add password failed";
+
+else if (!rc_avpair_add(h, &send, PW_SERVICE_TYPE, &service, 0, 0))
+  *errptr = US"RADIUS: add service type failed";
+
+#endif  /* RADIUS_LIB_RADIUSCLIENT */
+
+if (*errptr)
+  {
+  DEBUG(D_auth) debug_printf("%s\n", *errptr);
+  return ERROR;
+  }
+
+#ifdef RADIUS_LIB_RADIUSCLIENT
+result = rc_auth(0, send, &received, msg);
+#else
+result = rc_auth(h, 0, send, &received, msg);
+#endif
+
+DEBUG(D_auth) debug_printf("RADIUS code returned %d\n", result);
+
+switch (result)
+  {
+  case OK_RC:
+    return OK;
+
+  case REJECT_RC:
+  case ERROR_RC:
+    return FAIL;
+
+  case TIMEOUT_RC:
+    *errptr = US"RADIUS: timed out";
+    return ERROR;
+
+  case BADRESP_RC:
+  default:
+    *errptr = string_sprintf("RADIUS: unexpected response (%d)", result);
+    return ERROR;
+  }
+
+#else  /* RADIUS_LIB_RADLIB is set */
+
+/* Authenticate using the libradius library */
+
+if (!(h = rad_auth_open()))
+  {
+  *errptr = string_sprintf("RADIUS: can't initialise libradius");
+  return ERROR;
+  }
+if (rad_config(h, RADIUS_CONFIG_FILE) != 0 ||
+    rad_create_request(h, RAD_ACCESS_REQUEST) != 0 ||
+    rad_put_string(h, RAD_USER_NAME, CS user) != 0 ||
+    rad_put_string(h, RAD_USER_PASSWORD, CS radius_args) != 0 ||
+    rad_put_int(h, RAD_SERVICE_TYPE, RAD_AUTHENTICATE_ONLY) != 0 ||
+    rad_put_string(h, RAD_NAS_IDENTIFIER, CS primary_hostname) != 0)
+  {
+  *errptr = string_sprintf("RADIUS: %s", rad_strerror(h));
+  result = ERROR;
+  }
+else
+  switch (result = rad_send_request(h))
+    {
+    case RAD_ACCESS_ACCEPT:
+      result = OK;
+      break;
+
+    case RAD_ACCESS_REJECT:
+      result = FAIL;
+      break;
+
+    case -1:
+      *errptr = string_sprintf("RADIUS: %s", rad_strerror(h));
+      result = ERROR;
+      break;
+
+    default:
+      *errptr = string_sprintf("RADIUS: unexpected response (%d)", result);
+      result= ERROR;
+      break;
+    }
+
+if (*errptr) DEBUG(D_auth) debug_printf("%s\n", *errptr);
+rad_close(h);
+return result;
+
+#endif  /* RADIUS_LIB_RADLIB */
+}
+
+#endif  /* RADIUS_CONFIG_FILE */
+
+/* End of call_radius.c */
diff --git a/src/auths/check_serv_cond.c b/src/auths/check_serv_cond.c
new file mode 100644
index 0000000..457a715
--- /dev/null
+++ b/src/auths/check_serv_cond.c
@@ -0,0 +1,124 @@
+/*************************************************
+*     Exim - an Internet mail transport agent    *
+*************************************************/
+
+/* Copyright (c) University of Cambridge 1995 - 2012 */
+/* See the file NOTICE for conditions of use and distribution. */
+
+#include "../exim.h"
+
+/* This module contains the function server_condition(), which is used
+by all authenticators. */
+
+
+/*************************************************
+*              Check server_condition            *
+*************************************************/
+
+/* This function is called from the server code of all authenticators. For
+plaintext and gsasl, it is always called: the argument cannot be empty, because
+for those, setting server_condition is what enables it as a server
+authenticator. For all the other authenticators, this function is called after
+they have authenticated, to enable additional authorization to be done.
+
+Argument:     the authenticator's instance block
+
+Returns:
+  OK          NULL argument, or success
+  DEFER       couldn't complete the check
+  FAIL        authentication failed
+*/
+
+int
+auth_check_serv_cond(auth_instance *ablock)
+{
+  return auth_check_some_cond(ablock,
+      US"server_condition", ablock->server_condition, OK);
+}
+
+
+/*************************************************
+*         Check some server condition            *
+*************************************************/
+
+/* This underlies server_condition, but is also used for some more generic
+ checks.
+
+Arguments:
+  ablock     the authenticator's instance block
+  label      debugging label naming the string checked
+  condition  the condition string to be expanded and checked
+  unset      value to return on NULL condition
+
+Returns:
+  OK          success (or unset=OK)
+  DEFER       couldn't complete the check
+  FAIL        authentication failed
+*/
+
+int
+auth_check_some_cond(auth_instance *ablock,
+    uschar *label, uschar *condition, int unset)
+{
+uschar *cond;
+
+HDEBUG(D_auth)
+  {
+  debug_printf("%s authenticator %s:\n", ablock->name, label);
+  for (int i = 0; i < AUTH_VARS; i++) if (auth_vars[i])
+    debug_printf("  $auth%d = %s\n", i + 1, auth_vars[i]);
+  for (int i = 1; i <= expand_nmax; i++)
+    debug_printf("  $%d = %.*s\n", i, expand_nlength[i], expand_nstring[i]);
+  debug_print_string(ablock->server_debug_string);    /* customized debug */
+  }
+
+/* For the plaintext authenticator, server_condition is never NULL. For the
+rest, an unset condition lets everything through. */
+
+/* For server_condition, an unset condition lets everything through.
+For plaintext/gsasl authenticators, it will have been pre-checked to prevent
+this.  We return the unset scenario value given to us, which for
+server_condition will be OK and otherwise will typically be FAIL. */
+
+if (!condition) return unset;
+cond = expand_string(condition);
+
+HDEBUG(D_auth)
+  if (!cond)
+    debug_printf("expansion failed: %s\n", expand_string_message);
+  else
+    debug_printf("expanded string: %s\n", cond);
+
+/* A forced expansion failure causes authentication to fail. Other expansion
+failures yield DEFER, which will cause a temporary error code to be returned to
+the AUTH command. The problem is at the server end, so the client should try
+again later. */
+
+if (!cond)
+  {
+  if (f.expand_string_forcedfail) return FAIL;
+  auth_defer_msg = expand_string_message;
+  return DEFER;
+  }
+
+/* Return FAIL for empty string, "0", "no", and "false"; return OK for
+"1", "yes", and "true"; return DEFER for anything else, with the string
+available as an error text for the user. */
+
+if (*cond == 0 ||
+    Ustrcmp(cond, "0") == 0 ||
+    strcmpic(cond, US"no") == 0 ||
+    strcmpic(cond, US"false") == 0)
+  return FAIL;
+
+if (Ustrcmp(cond, "1") == 0 ||
+    strcmpic(cond, US"yes") == 0 ||
+    strcmpic(cond, US"true") == 0)
+  return OK;
+
+auth_defer_msg = cond;
+auth_defer_user_msg = string_sprintf(": %s", cond);
+return DEFER;
+}
+
+/* End of check_serv_cond.c */
diff --git a/src/auths/cram_md5.c b/src/auths/cram_md5.c
new file mode 100644
index 0000000..2c0616c
--- /dev/null
+++ b/src/auths/cram_md5.c
@@ -0,0 +1,360 @@
+/*************************************************
+*     Exim - an Internet mail transport agent    *
+*************************************************/
+
+/* Copyright (c) University of Cambridge 1995 - 2018 */
+/* Copyright (c) The Exim Maintainers 2020 */
+/* See the file NOTICE for conditions of use and distribution. */
+
+
+/* The stand-alone version just tests the algorithm. We have to drag
+in the MD5 computation functions, without their own stand-alone main
+program. */
+
+#ifdef STAND_ALONE
+#define CRAM_STAND_ALONE
+#include "md5.c"
+
+
+/* This is the normal, non-stand-alone case */
+
+#else
+#include "../exim.h"
+#include "cram_md5.h"
+
+/* Options specific to the cram_md5 authentication mechanism. */
+
+optionlist auth_cram_md5_options[] = {
+  { "client_name",        opt_stringptr,
+      OPT_OFF(auth_cram_md5_options_block, client_name) },
+  { "client_secret",      opt_stringptr,
+      OPT_OFF(auth_cram_md5_options_block, client_secret) },
+  { "server_secret",      opt_stringptr,
+      OPT_OFF(auth_cram_md5_options_block, server_secret) }
+};
+
+/* Size of the options list. An extern variable has to be used so that its
+address can appear in the tables drtables.c. */
+
+int auth_cram_md5_options_count =
+  sizeof(auth_cram_md5_options)/sizeof(optionlist);
+
+/* Default private options block for the condition authentication method. */
+
+auth_cram_md5_options_block auth_cram_md5_option_defaults = {
+  NULL,             /* server_secret */
+  NULL,             /* client_secret */
+  NULL              /* client_name */
+};
+
+
+#ifdef MACRO_PREDEF
+
+/* Dummy values */
+void auth_cram_md5_init(auth_instance *ablock) {}
+int auth_cram_md5_server(auth_instance *ablock, uschar *data) {return 0;}
+int auth_cram_md5_client(auth_instance *ablock, void *sx, int timeout,
+    uschar *buffer, int buffsize) {return 0;}
+
+#else	/*!MACRO_PREDEF*/
+
+
+/*************************************************
+*          Initialization entry point            *
+*************************************************/
+
+/* Called for each instance, after its options have been read, to
+enable consistency checks to be done, or anything else that needs
+to be set up. */
+
+void
+auth_cram_md5_init(auth_instance *ablock)
+{
+auth_cram_md5_options_block *ob =
+  (auth_cram_md5_options_block *)(ablock->options_block);
+if (ob->server_secret != NULL) ablock->server = TRUE;
+if (ob->client_secret != NULL)
+  {
+  ablock->client = TRUE;
+  if (ob->client_name == NULL) ob->client_name = primary_hostname;
+  }
+}
+
+#endif	/*!MACRO_PREDEF*/
+#endif  /* STAND_ALONE */
+
+
+
+#ifndef MACRO_PREDEF
+/*************************************************
+*      Perform the CRAM-MD5 algorithm            *
+*************************************************/
+
+/* The CRAM-MD5 algorithm is described in RFC 2195. It computes
+
+  MD5((secret XOR opad), MD5((secret XOR ipad), challenge))
+
+where secret is padded out to 64 characters (after being reduced to an MD5
+digest if longer than 64) and ipad and opad are 64-byte strings of 0x36 and
+0x5c respectively, and comma means concatenation.
+
+Arguments:
+  secret         the shared secret
+  challenge      the challenge text
+  digest         16-byte slot to put the answer in
+
+Returns:         nothing
+*/
+
+static void
+compute_cram_md5(uschar *secret, uschar *challenge, uschar *digestptr)
+{
+md5 base;
+int len = Ustrlen(secret);
+uschar isecret[64];
+uschar osecret[64];
+uschar md5secret[16];
+
+/* If the secret is longer than 64 characters, we compute its MD5 digest
+and use that. */
+
+if (len > 64)
+  {
+  md5_start(&base);
+  md5_end(&base, US secret, len, md5secret);
+  secret = US md5secret;
+  len = 16;
+  }
+
+/* The key length is now known to be <= 64. Set up the padded and xor'ed
+versions. */
+
+memcpy(isecret, secret, len);
+memset(isecret+len, 0, 64-len);
+memcpy(osecret, isecret, 64);
+
+for (int i = 0; i < 64; i++)
+  {
+  isecret[i] ^= 0x36;
+  osecret[i] ^= 0x5c;
+  }
+
+/* Compute the inner MD5 digest */
+
+md5_start(&base);
+md5_mid(&base, isecret);
+md5_end(&base, US challenge, Ustrlen(challenge), md5secret);
+
+/* Compute the outer MD5 digest */
+
+md5_start(&base);
+md5_mid(&base, osecret);
+md5_end(&base, md5secret, 16, digestptr);
+}
+
+
+#ifndef STAND_ALONE
+
+/*************************************************
+*             Server entry point                 *
+*************************************************/
+
+/* For interface, see auths/README */
+
+int
+auth_cram_md5_server(auth_instance *ablock, uschar *data)
+{
+auth_cram_md5_options_block *ob =
+  (auth_cram_md5_options_block *)(ablock->options_block);
+uschar *challenge = string_sprintf("<%d.%ld@%s>", getpid(),
+    (long int) time(NULL), primary_hostname);
+uschar *clear, *secret;
+uschar digest[16];
+int i, rc, len;
+
+/* If we are running in the test harness, always send the same challenge,
+an example string taken from the RFC. */
+
+if (f.running_in_test_harness)
+  challenge = US"<1896.697170952@postoffice.reston.mci.net>";
+
+/* No data should have been sent with the AUTH command */
+
+if (*data) return UNEXPECTED;
+
+/* Send the challenge, read the return */
+
+if ((rc = auth_get_data(&data, challenge, Ustrlen(challenge))) != OK) return rc;
+if ((len = b64decode(data, &clear)) < 0) return BAD64;
+
+/* The return consists of a user name, space-separated from the CRAM-MD5
+digest, expressed in hex. Extract the user name and put it in $auth1 and $1.
+The former is now the preferred variable; the latter is the original one. Then
+check that the remaining length is 32. */
+
+auth_vars[0] = expand_nstring[1] = clear;
+while (*clear && !isspace(*clear)) clear++;
+if (!isspace(*clear)) return FAIL;
+*clear++ = 0;
+
+expand_nlength[1] = clear - expand_nstring[1] - 1;
+if (len - expand_nlength[1] - 1 != 32) return FAIL;
+expand_nmax = 1;
+
+/* Expand the server_secret string so that it can compute a value dependent on
+the user name if necessary. */
+
+debug_print_string(ablock->server_debug_string);    /* customized debugging */
+secret = expand_string(ob->server_secret);
+
+/* A forced fail implies failure of authentication - i.e. we have no secret for
+the given name. */
+
+if (secret == NULL)
+  {
+  if (f.expand_string_forcedfail) return FAIL;
+  auth_defer_msg = expand_string_message;
+  return DEFER;
+  }
+
+/* Compute the CRAM-MD5 digest that we should have received from the client. */
+
+compute_cram_md5(secret, challenge, digest);
+
+HDEBUG(D_auth)
+  {
+  uschar buff[64];
+  debug_printf("CRAM-MD5: user name = %s\n", auth_vars[0]);
+  debug_printf("          challenge = %s\n", challenge);
+  debug_printf("          received  = %s\n", clear);
+  Ustrcpy(buff, US"          digest    = ");
+  for (i = 0; i < 16; i++) sprintf(CS buff+22+2*i, "%02x", digest[i]);
+  debug_printf("%.54s\n", buff);
+  }
+
+/* We now have to compare the digest, which is 16 bytes in binary, with the
+data received, which is expressed in lower case hex. We checked above that
+there were 32 characters of data left. */
+
+for (i = 0; i < 16; i++)
+  {
+  int a = *clear++;
+  int b = *clear++;
+  if (((((a >= 'a')? a - 'a' + 10 : a - '0') << 4) +
+        ((b >= 'a')? b - 'a' + 10 : b - '0')) != digest[i]) return FAIL;
+  }
+
+/* Expand server_condition as an authorization check */
+return auth_check_serv_cond(ablock);
+}
+
+
+
+/*************************************************
+*              Client entry point                *
+*************************************************/
+
+/* For interface, see auths/README */
+
+int
+auth_cram_md5_client(
+  auth_instance *ablock,                 /* authenticator block */
+  void * sx,				 /* smtp connextion */
+  int timeout,                           /* command timeout */
+  uschar *buffer,                        /* for reading response */
+  int buffsize)                          /* size of buffer */
+{
+auth_cram_md5_options_block *ob =
+  (auth_cram_md5_options_block *)(ablock->options_block);
+uschar *secret = expand_string(ob->client_secret);
+uschar *name = expand_string(ob->client_name);
+uschar *challenge, *p;
+int i;
+uschar digest[16];
+
+/* If expansion of either the secret or the user name failed, return CANCELLED
+or ERROR, as appropriate. */
+
+if (!secret || !name)
+  {
+  if (f.expand_string_forcedfail)
+    {
+    *buffer = 0;           /* No message */
+    return CANCELLED;
+    }
+  string_format(buffer, buffsize, "expansion of \"%s\" failed in "
+    "%s authenticator: %s",
+    !secret ? ob->client_secret : ob->client_name,
+    ablock->name, expand_string_message);
+  return ERROR;
+  }
+
+/* Initiate the authentication exchange and read the challenge, which arrives
+in base 64. */
+
+if (smtp_write_command(sx, SCMD_FLUSH, "AUTH %s\r\n", ablock->public_name) < 0)
+  return FAIL_SEND;
+if (!smtp_read_response(sx, buffer, buffsize, '3', timeout))
+  return FAIL;
+
+if (b64decode(buffer + 4, &challenge) < 0)
+  {
+  string_format(buffer, buffsize, "bad base 64 string in challenge: %s",
+    big_buffer + 4);
+  return ERROR;
+  }
+
+/* Run the CRAM-MD5 algorithm on the secret and the challenge */
+
+compute_cram_md5(secret, challenge, digest);
+
+/* Create the response from the user name plus the CRAM-MD5 digest */
+
+string_format(big_buffer, big_buffer_size - 36, "%s", name);
+for (p = big_buffer; *p; ) p++;
+*p++ = ' ';
+
+for (i = 0; i < 16; i++)
+  p += sprintf(CS p, "%02x", digest[i]);
+
+/* Send the response, in base 64, and check the result. The response is
+in big_buffer, but b64encode() returns its result in working store,
+so calling smtp_write_command(), which uses big_buffer, is OK. */
+
+buffer[0] = 0;
+if (smtp_write_command(sx, SCMD_FLUSH, "%s\r\n", b64encode(CUS big_buffer,
+  p - big_buffer)) < 0) return FAIL_SEND;
+
+return smtp_read_response(sx, US buffer, buffsize, '2', timeout)
+  ? OK : FAIL;
+}
+#endif  /* STAND_ALONE */
+
+
+/*************************************************
+**************************************************
+*             Stand-alone test program           *
+**************************************************
+*************************************************/
+
+#ifdef STAND_ALONE
+
+int main(int argc, char **argv)
+{
+int i;
+uschar *secret = US argv[1];
+uschar *challenge = US argv[2];
+uschar digest[16];
+
+compute_cram_md5(secret, challenge, digest);
+
+for (i = 0; i < 16; i++) printf("%02x", digest[i]);
+printf("\n");
+
+return 0;
+}
+
+#endif
+
+#endif	/*!MACRO_PREDEF*/
+/* End of cram_md5.c */
diff --git a/src/auths/cram_md5.h b/src/auths/cram_md5.h
new file mode 100644
index 0000000..95644db
--- /dev/null
+++ b/src/auths/cram_md5.h
@@ -0,0 +1,31 @@
+/*************************************************
+*     Exim - an Internet mail transport agent    *
+*************************************************/
+
+/* Copyright (c) University of Cambridge 1995 - 2009 */
+/* See the file NOTICE for conditions of use and distribution. */
+
+/* Private structure for the private options. */
+
+typedef struct {
+  uschar *server_secret;
+  uschar *client_secret;
+  uschar *client_name;
+} auth_cram_md5_options_block;
+
+/* Data for reading the private options. */
+
+extern optionlist auth_cram_md5_options[];
+extern int auth_cram_md5_options_count;
+
+/* Block containing default values. */
+
+extern auth_cram_md5_options_block auth_cram_md5_option_defaults;
+
+/* The entry points for the mechanism */
+
+extern void auth_cram_md5_init(auth_instance *);
+extern int auth_cram_md5_server(auth_instance *, uschar *);
+extern int auth_cram_md5_client(auth_instance *, void *, int, uschar *, int);
+
+/* End of cram_md5.h */
diff --git a/src/auths/cyrus_sasl.c b/src/auths/cyrus_sasl.c
new file mode 100644
index 0000000..ecaf23b
--- /dev/null
+++ b/src/auths/cyrus_sasl.c
@@ -0,0 +1,511 @@
+/*************************************************
+*     Exim - an Internet mail transport agent    *
+*************************************************/
+
+/* Copyright (c) University of Cambridge 1995 - 2018 */
+/* Copyright (c) The Exim Maintainers 2020 */
+/* See the file NOTICE for conditions of use and distribution. */
+
+/* This code was originally contributed by Matthew Byng-Maddick */
+
+/* Copyright (c) A L Digital 2004 */
+
+/* A generic (mechanism independent) Cyrus SASL authenticator. */
+
+
+#include "../exim.h"
+
+
+/* We can't just compile this code and allow the library mechanism to omit the
+functions if they are not wanted, because we need to have the Cyrus SASL header
+available for compiling. Therefore, compile these functions only if
+AUTH_CYRUS_SASL is defined. However, some compilers don't like compiling empty
+modules, so keep them happy with a dummy when skipping the rest. Make it
+reference itself to stop picky compilers complaining that it is unused, and put
+in a dummy argument to stop even pickier compilers complaining about infinite
+loops. */
+
+#ifndef AUTH_CYRUS_SASL
+static void dummy(int x);
+static void dummy2(int x) { dummy(x-1); }
+static void dummy(int x) { dummy2(x-1); }
+#else
+
+
+#include <sasl/sasl.h>
+#include "cyrus_sasl.h"
+
+/* Options specific to the cyrus_sasl authentication mechanism. */
+
+optionlist auth_cyrus_sasl_options[] = {
+  { "server_hostname",      opt_stringptr,
+      OPT_OFF(auth_cyrus_sasl_options_block, server_hostname) },
+  { "server_mech",          opt_stringptr,
+      OPT_OFF(auth_cyrus_sasl_options_block, server_mech) },
+  { "server_realm",         opt_stringptr,
+      OPT_OFF(auth_cyrus_sasl_options_block, server_realm) },
+  { "server_service",       opt_stringptr,
+      OPT_OFF(auth_cyrus_sasl_options_block, server_service) }
+};
+
+/* Size of the options list. An extern variable has to be used so that its
+address can appear in the tables drtables.c. */
+
+int auth_cyrus_sasl_options_count =
+  sizeof(auth_cyrus_sasl_options)/sizeof(optionlist);
+
+/* Default private options block for the cyrus_sasl authentication method. */
+
+auth_cyrus_sasl_options_block auth_cyrus_sasl_option_defaults = {
+  US"smtp",         /* server_service */
+  US"$primary_hostname", /* server_hostname */
+  NULL,             /* server_realm */
+  NULL              /* server_mech */
+};
+
+
+#ifdef MACRO_PREDEF
+
+/* Dummy values */
+void auth_cyrus_sasl_init(auth_instance *ablock) {}
+int auth_cyrus_sasl_server(auth_instance *ablock, uschar *data) {return 0;}
+int auth_cyrus_sasl_client(auth_instance *ablock, void * sx,
+  int timeout, uschar *buffer, int buffsize) {return 0;}
+void auth_cyrus_sasl_version_report(FILE *f) {}
+
+#else   /*!MACRO_PREDEF*/
+
+
+
+
+/*************************************************
+*          Initialization entry point            *
+*************************************************/
+
+/* Called for each instance, after its options have been read, to
+enable consistency checks to be done, or anything else that needs
+to be set up. */
+
+
+/* Auxiliary function, passed in data to sasl_server_init(). */
+
+static int
+mysasl_config(void *context, const char *plugin_name, const char *option,
+      const char **result, unsigned int *len)
+{
+if (context && !strcmp(option, "mech_list"))
+  {
+  *result = context;
+  if (len) *len = strlen(*result);
+  return SASL_OK;
+  }
+return SASL_FAIL;
+}
+
+/* Here's the real function */
+
+void
+auth_cyrus_sasl_init(auth_instance *ablock)
+{
+auth_cyrus_sasl_options_block *ob =
+  (auth_cyrus_sasl_options_block *)(ablock->options_block);
+const uschar *list, *listptr, *buffer;
+int rc, i;
+unsigned int len;
+rmark rs_point;
+uschar *expanded_hostname;
+char *realm_expanded;
+
+sasl_conn_t *conn;
+sasl_callback_t cbs[] = {
+  {SASL_CB_GETOPT, NULL, NULL },
+  {SASL_CB_LIST_END, NULL, NULL}};
+
+/* default the mechanism to our "public name" */
+
+if (!ob->server_mech) ob->server_mech = string_copy(ablock->public_name);
+
+if (!(expanded_hostname = expand_string(ob->server_hostname)))
+  log_write(0, LOG_PANIC_DIE|LOG_CONFIG_FOR, "%s authenticator:  "
+      "couldn't expand server_hostname [%s]: %s",
+      ablock->name, ob->server_hostname, expand_string_message);
+
+realm_expanded = NULL;
+if (  ob->server_realm
+   && !(realm_expanded = CS expand_string(ob->server_realm)))
+  log_write(0, LOG_PANIC_DIE|LOG_CONFIG_FOR, "%s authenticator:  "
+      "couldn't expand server_realm [%s]: %s",
+      ablock->name, ob->server_realm, expand_string_message);
+
+/* we're going to initialise the library to check that there is an
+authenticator of type whatever mechanism we're using */
+
+cbs[0].proc = (int(*)(void)) &mysasl_config;
+cbs[0].context = ob->server_mech;
+
+if ((rc = sasl_server_init(cbs, "exim")) != SASL_OK)
+  log_write(0, LOG_PANIC_DIE|LOG_CONFIG_FOR, "%s authenticator:  "
+      "couldn't initialise Cyrus SASL library.", ablock->name);
+
+if ((rc = sasl_server_new(CS ob->server_service, CS expanded_hostname,
+                   realm_expanded, NULL, NULL, NULL, 0, &conn)) != SASL_OK)
+  log_write(0, LOG_PANIC_DIE|LOG_CONFIG_FOR, "%s authenticator:  "
+      "couldn't initialise Cyrus SASL server connection.", ablock->name);
+
+if ((rc = sasl_listmech(conn, NULL, "", ":", "", CCSS &list, &len, &i)) != SASL_OK)
+  log_write(0, LOG_PANIC_DIE|LOG_CONFIG_FOR, "%s authenticator:  "
+      "couldn't get Cyrus SASL mechanism list.", ablock->name);
+
+i = ':';
+listptr = list;
+
+HDEBUG(D_auth)
+  {
+  debug_printf("Initialised Cyrus SASL service=\"%s\" fqdn=\"%s\" realm=\"%s\"\n",
+      ob->server_service, expanded_hostname, realm_expanded);
+  debug_printf("Cyrus SASL knows mechanisms: %s\n", list);
+  }
+
+/* the store_get / store_reset mechanism is hierarchical
+ the hierarchy is stored for us behind our back. This point
+ creates a hierarchy point for this function.  */
+
+rs_point = store_mark();
+
+/* loop until either we get to the end of the list, or we match the
+public name of this authenticator */
+
+while (  (buffer = string_nextinlist(&listptr, &i, NULL, 0))
+      && strcmpic(buffer,ob->server_mech) );
+
+if (!buffer)
+  log_write(0, LOG_PANIC_DIE|LOG_CONFIG_FOR, "%s authenticator:  "
+      "Cyrus SASL doesn't know about mechanism %s.", ablock->name, ob->server_mech);
+
+store_reset(rs_point);
+
+HDEBUG(D_auth) debug_printf("Cyrus SASL driver %s: %s initialised\n", ablock->name, ablock->public_name);
+
+/* make sure that if we get here then we're allowed to advertise. */
+ablock->server = TRUE;
+
+sasl_dispose(&conn);
+sasl_done();
+}
+
+/*************************************************
+*             Server entry point                 *
+*************************************************/
+
+/* For interface, see auths/README */
+
+/* note, we don't care too much about memory allocation in this, because this is entirely
+within a shortlived child */
+
+int
+auth_cyrus_sasl_server(auth_instance *ablock, uschar *data)
+{
+auth_cyrus_sasl_options_block *ob =
+  (auth_cyrus_sasl_options_block *)(ablock->options_block);
+uschar *output, *out2, *input, *clear, *hname;
+uschar *debug = NULL;   /* Stops compiler complaining */
+sasl_callback_t cbs[] = {{SASL_CB_LIST_END, NULL, NULL}};
+sasl_conn_t *conn;
+char * realm_expanded = NULL;
+int rc, firsttime = 1, clen, *negotiated_ssf_ptr = NULL, negotiated_ssf;
+unsigned int inlen, outlen;
+
+input = data;
+inlen = Ustrlen(data);
+
+HDEBUG(D_auth) debug = string_copy(data);
+
+hname = expand_string(ob->server_hostname);
+if (hname && ob->server_realm)
+  realm_expanded = CS expand_string(ob->server_realm);
+if (!hname  ||  !realm_expanded  && ob->server_realm)
+  {
+  auth_defer_msg = expand_string_message;
+  return DEFER;
+  }
+
+if (inlen)
+  {
+  if ((clen = b64decode(input, &clear)) < 0)
+    return BAD64;
+  input = clear;
+  inlen = clen;
+  }
+
+if ((rc = sasl_server_init(cbs, "exim")) != SASL_OK)
+  {
+  auth_defer_msg = US"couldn't initialise Cyrus SASL library";
+  return DEFER;
+  }
+
+rc = sasl_server_new(CS ob->server_service, CS hname, realm_expanded, NULL,
+  NULL, NULL, 0, &conn);
+
+HDEBUG(D_auth)
+  debug_printf("Initialised Cyrus SASL server connection; service=\"%s\" fqdn=\"%s\" realm=\"%s\"\n",
+      ob->server_service, hname, realm_expanded);
+
+if (rc != SASL_OK )
+  {
+  auth_defer_msg = US"couldn't initialise Cyrus SASL connection";
+  sasl_done();
+  return DEFER;
+  }
+
+if (tls_in.cipher)
+  {
+  if ((rc = sasl_setprop(conn, SASL_SSF_EXTERNAL, (sasl_ssf_t *) &tls_in.bits)) != SASL_OK)
+    {
+    HDEBUG(D_auth) debug_printf("Cyrus SASL EXTERNAL SSF set %d failed: %s\n",
+        tls_in.bits, sasl_errstring(rc, NULL, NULL));
+    auth_defer_msg = US"couldn't set Cyrus SASL EXTERNAL SSF";
+    sasl_done();
+    return DEFER;
+    }
+  else
+    HDEBUG(D_auth) debug_printf("Cyrus SASL set EXTERNAL SSF to %d\n", tls_in.bits);
+
+  /*XXX Set channel-binding here with sasl_channel_binding_t / SASL_CHANNEL_BINDING
+  Unclear what the "name" element does though, ditto the "critical" flag. */
+  }
+else
+  HDEBUG(D_auth) debug_printf("Cyrus SASL: no TLS, no EXTERNAL SSF set\n");
+
+/* So sasl_setprop() documents non-shorted IPv6 addresses which is incredibly
+annoying; looking at cyrus-imapd-2.3.x source, the IP address is constructed
+with their iptostring() function, which just wraps
+getnameinfo(..., NI_NUMERICHOST|NI_NUMERICSERV), which is equivalent to the
+inet_ntop which we wrap in our host_ntoa() function.
+
+So the docs are too strict and we shouldn't worry about :: contractions. */
+
+/* Set properties for remote and local host-ip;port */
+for (int i = 0; i < 2; ++i)
+  {
+  int propnum;
+  const uschar * label;
+  uschar * address_port;
+  const char *s_err;
+
+  if (i)
+    {
+    propnum = SASL_IPREMOTEPORT;
+    label = CUS"peer";
+    address_port = string_sprintf("%s;%d",
+				  sender_host_address, sender_host_port);
+    }
+  else
+    {
+    propnum = SASL_IPLOCALPORT;
+    label = CUS"local";
+    address_port = string_sprintf("%s;%d", interface_address, interface_port);
+    }
+
+  if ((rc = sasl_setprop(conn, propnum, address_port)) != SASL_OK)
+    {
+    HDEBUG(D_auth)
+      {
+      s_err = sasl_errdetail(conn);
+      debug_printf("Failed to set %s SASL property: [%d] %s\n",
+          label, rc, s_err ? s_err : "<unknown reason>");
+      }
+    break;
+    }
+  HDEBUG(D_auth) debug_printf("Cyrus SASL set %s hostport to: %s\n",
+      label, address_port);
+  }
+
+for (rc = SASL_CONTINUE; rc == SASL_CONTINUE; )
+  {
+  if (firsttime)
+    {
+    firsttime = 0;
+    HDEBUG(D_auth) debug_printf("Calling sasl_server_start(%s,\"%s\")\n", ob->server_mech, debug);
+    rc = sasl_server_start(conn, CS ob->server_mech, inlen ? CS input : NULL, inlen,
+           CCSS &output, &outlen);
+    }
+  else
+    {
+    /* auth_get_data() takes a length-specfied block of binary
+    which can include zeroes; no terminating NUL is needed */
+
+    if ((rc = auth_get_data(&input, output, outlen)) != OK)
+      {
+      /* we couldn't get the data, so free up the library before
+      returning whatever error we get */
+      sasl_dispose(&conn);
+      sasl_done();
+      return rc;
+      }
+    inlen = Ustrlen(input);
+
+    HDEBUG(D_auth) debug = string_copy(input);
+    if (inlen)
+      {
+      if ((clen = b64decode(input, &clear)) < 0)
+       {
+       sasl_dispose(&conn);
+       sasl_done();
+       return BAD64;
+       }
+      input = clear;
+      inlen = clen;
+      }
+
+    HDEBUG(D_auth) debug_printf("Calling sasl_server_step(\"%s\")\n", debug);
+    rc = sasl_server_step(conn, CS input, inlen, CCSS &output, &outlen);
+    }
+
+  if (rc == SASL_BADPROT)
+    {
+    sasl_dispose(&conn);
+    sasl_done();
+    return UNEXPECTED;
+    }
+  if (rc == SASL_CONTINUE)
+    continue;
+
+  /* Get the username and copy it into $auth1 and $1. The former is now the
+  preferred variable; the latter is the original variable. */
+
+  if ((sasl_getprop(conn, SASL_USERNAME, (const void **)&out2)) != SASL_OK)
+    {
+    HDEBUG(D_auth)
+      debug_printf("Cyrus SASL library will not tell us the username: %s\n",
+	  sasl_errstring(rc, NULL, NULL));
+    log_write(0, LOG_REJECT, "%s authenticator (%s):\n  "
+       "Cyrus SASL username fetch problem: %s", ablock->name, ob->server_mech,
+       sasl_errstring(rc, NULL, NULL));
+    sasl_dispose(&conn);
+    sasl_done();
+    return FAIL;
+    }
+  auth_vars[0] = expand_nstring[1] = string_copy(out2);
+  expand_nlength[1] = Ustrlen(out2);
+  expand_nmax = 1;
+
+  switch (rc)
+    {
+    case SASL_FAIL: case SASL_BUFOVER: case SASL_BADMAC: case SASL_BADAUTH:
+    case SASL_NOAUTHZ: case SASL_ENCRYPT: case SASL_EXPIRED:
+    case SASL_DISABLED: case SASL_NOUSER:
+      /* these are considered permanent failure codes */
+      HDEBUG(D_auth)
+	debug_printf("Cyrus SASL permanent failure %d (%s)\n", rc, sasl_errstring(rc, NULL, NULL));
+      log_write(0, LOG_REJECT, "%s authenticator (%s):\n  "
+	 "Cyrus SASL permanent failure: %s", ablock->name, ob->server_mech,
+	 sasl_errstring(rc, NULL, NULL));
+      sasl_dispose(&conn);
+      sasl_done();
+      return FAIL;
+
+    case SASL_NOMECH:
+      /* this is a temporary failure, because the mechanism is not
+      available for this user. If it wasn't available at all, we
+      shouldn't have got here in the first place...  */
+
+      HDEBUG(D_auth)
+	debug_printf("Cyrus SASL temporary failure %d (%s)\n", rc, sasl_errstring(rc, NULL, NULL));
+      auth_defer_msg =
+	  string_sprintf("Cyrus SASL: mechanism %s not available", ob->server_mech);
+      sasl_dispose(&conn);
+      sasl_done();
+      return DEFER;
+
+    case SASL_OK:
+      HDEBUG(D_auth)
+	debug_printf("Cyrus SASL %s authentication succeeded for %s\n",
+	    ob->server_mech, auth_vars[0]);
+
+      if ((rc = sasl_getprop(conn, SASL_SSF, (const void **)(&negotiated_ssf_ptr)))!= SASL_OK)
+	{
+	HDEBUG(D_auth)
+	  debug_printf("Cyrus SASL library will not tell us the SSF: %s\n",
+	      sasl_errstring(rc, NULL, NULL));
+	log_write(0, LOG_REJECT, "%s authenticator (%s):\n  "
+	    "Cyrus SASL SSF value not available: %s", ablock->name, ob->server_mech,
+	    sasl_errstring(rc, NULL, NULL));
+	sasl_dispose(&conn);
+	sasl_done();
+	return FAIL;
+	}
+      negotiated_ssf = *negotiated_ssf_ptr;
+      HDEBUG(D_auth)
+	debug_printf("Cyrus SASL %s negotiated SSF: %d\n", ob->server_mech, negotiated_ssf);
+      if (negotiated_ssf > 0)
+	{
+	HDEBUG(D_auth)
+	  debug_printf("Exim does not implement SASL wrapping (needed for SSF %d).\n", negotiated_ssf);
+	log_write(0, LOG_REJECT, "%s authenticator (%s):\n  "
+	    "Cyrus SASL SSF %d not supported by Exim", ablock->name, ob->server_mech, negotiated_ssf);
+	sasl_dispose(&conn);
+	sasl_done();
+	return FAIL;
+	}
+
+      /* close down the connection, freeing up library's memory */
+      sasl_dispose(&conn);
+      sasl_done();
+
+      /* Expand server_condition as an authorization check */
+      return auth_check_serv_cond(ablock);
+
+    default:
+      /* Anything else is a temporary failure, and we'll let SASL print out
+       * the error string for us
+       */
+      HDEBUG(D_auth)
+	debug_printf("Cyrus SASL temporary failure %d (%s)\n", rc, sasl_errstring(rc, NULL, NULL));
+      auth_defer_msg =
+	  string_sprintf("Cyrus SASL: %s", sasl_errstring(rc, NULL, NULL));
+      sasl_dispose(&conn);
+      sasl_done();
+      return DEFER;
+    }
+  }
+/* NOTREACHED */
+return 0;  /* Stop compiler complaints */
+}
+
+/*************************************************
+*                Diagnostic API                  *
+*************************************************/
+
+void
+auth_cyrus_sasl_version_report(FILE *f)
+{
+const char *implementation, *version;
+sasl_version_info(&implementation, &version, NULL, NULL, NULL, NULL);
+fprintf(f, "Library version: Cyrus SASL: Compile: %d.%d.%d\n"
+	   "                             Runtime: %s [%s]\n",
+	SASL_VERSION_MAJOR, SASL_VERSION_MINOR, SASL_VERSION_STEP,
+	version, implementation);
+}
+
+/*************************************************
+*              Client entry point                *
+*************************************************/
+
+/* For interface, see auths/README */
+
+int
+auth_cyrus_sasl_client(
+  auth_instance *ablock,                 /* authenticator block */
+  void * sx,			 	 /* connexction */
+  int timeout,                           /* command timeout */
+  uschar *buffer,                        /* for reading response */
+  int buffsize)                          /* size of buffer */
+{
+/* We don't support clients (yet) in this implementation of cyrus_sasl */
+return FAIL;
+}
+
+#endif   /*!MACRO_PREDEF*/
+#endif  /* AUTH_CYRUS_SASL */
+
+/* End of cyrus_sasl.c */
diff --git a/src/auths/cyrus_sasl.h b/src/auths/cyrus_sasl.h
new file mode 100644
index 0000000..da6f3cd
--- /dev/null
+++ b/src/auths/cyrus_sasl.h
@@ -0,0 +1,35 @@
+/*************************************************
+*     Exim - an Internet mail transport agent    *
+*************************************************/
+
+/* Copyright (c) University of Cambridge 1995 - 2012 */
+/* See the file NOTICE for conditions of use and distribution. */
+
+/* Copyright (c) A L Digital Ltd 2004 */
+
+/* Private structure for the private options. */
+
+typedef struct {
+  uschar *server_service;
+  uschar *server_hostname;
+  uschar *server_realm;
+  uschar *server_mech;
+} auth_cyrus_sasl_options_block;
+
+/* Data for reading the private options. */
+
+extern optionlist auth_cyrus_sasl_options[];
+extern int auth_cyrus_sasl_options_count;
+
+/* Block containing default values. */
+
+extern auth_cyrus_sasl_options_block auth_cyrus_sasl_option_defaults;
+
+/* The entry points for the mechanism */
+
+extern void auth_cyrus_sasl_init(auth_instance *);
+extern int auth_cyrus_sasl_server(auth_instance *, uschar *);
+extern int auth_cyrus_sasl_client(auth_instance *, void *, int, uschar *, int);
+extern void auth_cyrus_sasl_version_report(FILE *f);
+
+/* End of cyrus_sasl.h */
diff --git a/src/auths/dovecot.c b/src/auths/dovecot.c
new file mode 100644
index 0000000..3331cb8
--- /dev/null
+++ b/src/auths/dovecot.c
@@ -0,0 +1,521 @@
+/*
+ * Copyright (c) 2004 Andrey Panin <pazke@donpac.ru>
+ * Copyright (c) 2006-2020 The Exim Maintainers
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published
+ * by the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+/* A number of modifications have been made to the original code. Originally I
+commented them specially, but now they are getting quite extensive, so I have
+ceased doing that. The biggest change is to use unbuffered I/O on the socket
+because using C buffered I/O gives problems on some operating systems. PH */
+
+/* Protocol specifications:
+ * Dovecot 1, protocol version 1.1
+ *   http://wiki.dovecot.org/Authentication%20Protocol
+ *
+ * Dovecot 2, protocol version 1.1
+ *   http://wiki2.dovecot.org/Design/AuthProtocol
+ */
+
+#include "../exim.h"
+#include "dovecot.h"
+
+#define VERSION_MAJOR  1
+#define VERSION_MINOR  0
+
+/* http://wiki.dovecot.org/Authentication%20Protocol
+"The maximum line length isn't defined,
+ but it's currently expected to fit into 8192 bytes"
+*/
+#define DOVECOT_AUTH_MAXLINELEN 8192
+
+/* This was hard-coded as 8.
+AUTH req C->S sends {"AUTH", id, mechanism, service } + params, 5 defined for
+Dovecot 1; Dovecot 2 (same protocol version) defines 9.
+
+Master->Server sends {"USER", id, userid} + params, 6 defined.
+Server->Client only gives {"OK", id} + params, unspecified, only 1 guaranteed.
+
+We only define here to accept S->C; max seen is 3+<unspecified>, plus the two
+for the command and id, where unspecified might include _at least_ user=...
+
+So: allow for more fields than we ever expect to see, while aware that count
+can go up without changing protocol version.
+The cost is the length of an array of pointers on the stack.
+*/
+#define DOVECOT_AUTH_MAXFIELDCOUNT 16
+
+/* Options specific to the authentication mechanism. */
+optionlist auth_dovecot_options[] = {
+  { "server_socket", opt_stringptr, OPT_OFF(auth_dovecot_options_block, server_socket) },
+/*{ "server_tls", opt_bool, OPT_OFF(auth_dovecot_options_block, server_tls) },*/
+};
+
+/* Size of the options list. An extern variable has to be used so that its
+address can appear in the tables drtables.c. */
+
+int auth_dovecot_options_count = nelem(auth_dovecot_options);
+
+/* Default private options block for the authentication method. */
+
+auth_dovecot_options_block auth_dovecot_option_defaults = {
+	.server_socket = NULL,
+/*	.server_tls =	FALSE,*/
+};
+
+
+
+
+#ifdef MACRO_PREDEF
+
+/* Dummy values */
+void auth_dovecot_init(auth_instance *ablock) {}
+int auth_dovecot_server(auth_instance *ablock, uschar *data) {return 0;}
+int auth_dovecot_client(auth_instance *ablock, void * sx,
+  int timeout, uschar *buffer, int buffsize) {return 0;}
+
+#else   /*!MACRO_PREDEF*/
+
+
+/* Static variables for reading from the socket */
+
+static uschar sbuffer[256];
+static int socket_buffer_left;
+
+
+
+/*************************************************
+ *          Initialization entry point           *
+ *************************************************/
+
+/* Called for each instance, after its options have been read, to
+enable consistency checks to be done, or anything else that needs
+to be set up. */
+
+void auth_dovecot_init(auth_instance *ablock)
+{
+auth_dovecot_options_block *ob =
+       (auth_dovecot_options_block *)(ablock->options_block);
+
+if (!ablock->public_name) ablock->public_name = ablock->name;
+if (ob->server_socket) ablock->server = TRUE;
+ablock->client = FALSE;
+}
+
+/*************************************************
+ *    "strcut" to split apart server lines       *
+ *************************************************/
+
+/* Dovecot auth protocol uses TAB \t as delimiter; a line consists
+of a command-name, TAB, and then any parameters, each separated by a TAB.
+A parameter can be param=value or a bool, just param.
+
+This function modifies the original str in-place, inserting NUL characters.
+It initialises ptrs entries, setting all to NULL and only setting
+non-NULL N entries, where N is the return value, the number of fields seen
+(one more than the number of tabs).
+
+Note that the return value will always be at least 1, is the count of
+actual fields (so last valid offset into ptrs is one less).
+*/
+
+static int
+strcut(uschar *str, uschar **ptrs, int nptrs)
+{
+uschar *last_sub_start = str;
+int n;
+
+for (n = 0; n < nptrs; n++)
+  ptrs[n] = NULL;
+n = 1;
+
+while (*str)
+  if (*str++ == '\t')
+    if (n++ <= nptrs)
+      {
+      *ptrs++ = last_sub_start;
+      last_sub_start = str;
+      str[-1] = '\0';
+      }
+
+/* It's acceptable for the string to end with a tab character.  We see
+this in AUTH PLAIN without an initial response from the client, which
+causing us to send "334 " and get the data from the client. */
+if (n <= nptrs)
+  *ptrs = last_sub_start;
+else
+  {
+  HDEBUG(D_auth)
+    debug_printf("dovecot: warning: too many results from tab-splitting;"
+		  " saw %d fields, room for %d\n", n, nptrs);
+  n = nptrs;
+  }
+
+return n <= nptrs ? n : nptrs;
+}
+
+static void debug_strcut(uschar **ptrs, int nlen, int alen) ARG_UNUSED;
+static void
+debug_strcut(uschar **ptrs, int nlen, int alen)
+{
+int i;
+debug_printf("%d read but unreturned bytes; strcut() gave %d results: ",
+		socket_buffer_left, nlen);
+for (i = 0; i < nlen; i++)
+  debug_printf(" {%s}", ptrs[i]);
+if (nlen < alen)
+  debug_printf(" last is %s\n", ptrs[i] ? ptrs[i] : US"<null>");
+else
+  debug_printf(" (max for capacity)\n");
+}
+
+#define CHECK_COMMAND(str, arg_min, arg_max) do { \
+       if (strcmpic(US(str), args[0]) != 0) \
+               goto out; \
+       if (nargs - 1 < (arg_min)) \
+               goto out; \
+       if ( (arg_max != -1) && (nargs - 1 > (arg_max)) ) \
+               goto out; \
+} while (0)
+
+#define OUT(msg) do { \
+       auth_defer_msg = (US msg); \
+       goto out; \
+} while(0)
+
+
+
+/*************************************************
+*      "fgets" to read directly from socket      *
+*************************************************/
+
+/* Added by PH after a suggestion by Steve Usher because the previous use of
+C-style buffered I/O gave trouble. */
+
+static uschar *
+dc_gets(uschar *s, int n, client_conn_ctx * cctx)
+{
+int p = 0;
+int count = 0;
+
+for (;;)
+  {
+  if (socket_buffer_left == 0)
+    {
+    if ((socket_buffer_left =
+#ifndef DISABLE_TLS
+	cctx->tls_ctx ? tls_read(cctx->tls_ctx, sbuffer, sizeof(sbuffer)) :
+#endif
+	read(cctx->sock, sbuffer, sizeof(sbuffer))) <= 0)
+      if (count == 0)
+	return NULL;
+      else
+	break;
+    p = 0;
+    }
+
+  while (p < socket_buffer_left)
+    {
+    if (count >= n - 1) break;
+    s[count++] = sbuffer[p];
+    if (sbuffer[p++] == '\n') break;
+    }
+
+  memmove(sbuffer, sbuffer + p, socket_buffer_left - p);
+  socket_buffer_left -= p;
+
+  if (s[count-1] == '\n' || count >= n - 1) break;
+  }
+
+s[count] = '\0';
+return s;
+}
+
+
+
+
+/*************************************************
+*              Server entry point                *
+*************************************************/
+
+int
+auth_dovecot_server(auth_instance * ablock, uschar * data)
+{
+auth_dovecot_options_block *ob =
+       (auth_dovecot_options_block *) ablock->options_block;
+uschar buffer[DOVECOT_AUTH_MAXLINELEN];
+uschar *args[DOVECOT_AUTH_MAXFIELDCOUNT];
+uschar *auth_command;
+uschar *auth_extra_data = US"";
+uschar *p;
+int nargs, tmp;
+int crequid = 1, ret = DEFER;
+host_item host;
+client_conn_ctx cctx = {.sock = -1, .tls_ctx = NULL};
+BOOL found = FALSE, have_mech_line = FALSE;
+
+HDEBUG(D_auth) debug_printf("dovecot authentication\n");
+
+if (!data)
+  {
+  ret = FAIL;
+  goto out;
+  }
+
+/*XXX timeout? */
+cctx.sock = ip_streamsocket(ob->server_socket, &auth_defer_msg, 5, &host);
+if (cctx.sock < 0)
+ goto out;
+
+#ifdef notdef
+# ifndef DISABLE_TLS
+if (ob->server_tls)
+  {
+  uschar * s;
+  smtp_connect_args conn_args = { .host = &host };
+  tls_support tls_dummy = {.sni=NULL};
+  uschar * errstr;
+
+  if (!tls_client_start(&cctx, &conn_args, NULL, &tls_dummy, &errstr))
+    {
+    auth_defer_msg = string_sprintf("TLS connect failed: %s", errstr);
+    goto out;
+    }
+  }
+# endif
+#endif
+
+auth_defer_msg = US"authentication socket protocol error";
+
+socket_buffer_left = 0;  /* Global, used to read more than a line but return by line */
+for (;;)
+  {
+debug_printf("%s %d\n", __FUNCTION__, __LINE__);
+  if (!dc_gets(buffer, sizeof(buffer), &cctx))
+    OUT("authentication socket read error or premature eof");
+debug_printf("%s %d\n", __FUNCTION__, __LINE__);
+  p = buffer + Ustrlen(buffer) - 1;
+  if (*p != '\n')
+    OUT("authentication socket protocol line too long");
+
+  *p = '\0';
+  HDEBUG(D_auth) debug_printf("received: '%s'\n", buffer);
+
+  nargs = strcut(buffer, args, nelem(args));
+
+  HDEBUG(D_auth) debug_strcut(args, nargs, nelem(args));
+
+  /* Code below rewritten by Kirill Miazine (km@krot.org). Only check commands that
+    Exim will need. Original code also failed if Dovecot server sent unknown
+    command. E.g. COOKIE in version 1.1 of the protocol would cause troubles. */
+  /* pdp: note that CUID is a per-connection identifier sent by the server,
+    which increments at server discretion.
+    By contrast, the "id" field of the protocol is a connection-specific request
+    identifier, which needs to be unique per request from the client and is not
+    connected to the CUID value, so we ignore CUID from server.  It's purely for
+    diagnostics. */
+
+  if (Ustrcmp(args[0], US"VERSION") == 0)
+    {
+    CHECK_COMMAND("VERSION", 2, 2);
+    if (Uatoi(args[1]) != VERSION_MAJOR)
+      OUT("authentication socket protocol version mismatch");
+    }
+  else if (Ustrcmp(args[0], US"MECH") == 0)
+    {
+    CHECK_COMMAND("MECH", 1, INT_MAX);
+    have_mech_line = TRUE;
+    if (strcmpic(US args[1], ablock->public_name) == 0)
+      found = TRUE;
+    }
+  else if (Ustrcmp(args[0], US"SPID") == 0)
+    {
+    /* Unfortunately the auth protocol handshake wasn't designed well
+    to differentiate between auth-client/userdb/master. auth-userdb
+    and auth-master send VERSION + SPID lines only and nothing
+    afterwards, while auth-client sends VERSION + MECH + SPID +
+    CUID + more. The simplest way that we can determine if we've
+    connected to the correct socket is to see if MECH line exists or
+    not (alternatively we'd have to have a small timeout after SPID
+    to see if CUID is sent or not). */
+
+    if (!have_mech_line)
+      OUT("authentication socket type mismatch"
+	" (connected to auth-master instead of auth-client)");
+    }
+  else if (Ustrcmp(args[0], US"DONE") == 0)
+    {
+    CHECK_COMMAND("DONE", 0, 0);
+    break;
+    }
+  }
+
+if (!found)
+  {
+  auth_defer_msg = string_sprintf(
+    "Dovecot did not advertise mechanism \"%s\" to us", ablock->public_name);
+  goto out;
+  }
+
+/* Added by PH: data must not contain tab (as it is
+b64 it shouldn't, but check for safety). */
+
+if (Ustrchr(data, '\t') != NULL)
+  {
+  ret = FAIL;
+  goto out;
+  }
+
+/* Added by PH: extra fields when TLS is in use or if the TCP/IP
+connection is local. */
+
+if (tls_in.cipher)
+  auth_extra_data = string_sprintf("secured\t%s%s",
+     tls_in.certificate_verified ? "valid-client-cert" : "",
+     tls_in.certificate_verified ? "\t" : "");
+
+else if (  interface_address
+        && Ustrcmp(sender_host_address, interface_address) == 0)
+  auth_extra_data = US"secured\t";
+
+
+/****************************************************************************
+The code below was the original code here. It didn't work. A reading of the
+file auth-protocol.txt.gz that came with Dovecot 1.0_beta8 indicated that
+this was not right. Maybe something changed. I changed it to move the
+service indication into the AUTH command, and it seems to be better. PH
+
+fprintf(f, "VERSION\t%d\t%d\r\nSERVICE\tSMTP\r\nCPID\t%d\r\n"
+       "AUTH\t%d\t%s\trip=%s\tlip=%s\tresp=%s\r\n",
+       VERSION_MAJOR, VERSION_MINOR, getpid(), cuid,
+       ablock->public_name, sender_host_address, interface_address,
+       data ? CS  data : "");
+
+Subsequently, the command was modified to add "secured" and "valid-client-
+cert" when relevant.
+****************************************************************************/
+
+auth_command = string_sprintf("VERSION\t%d\t%d\nCPID\t%d\n"
+       "AUTH\t%d\t%s\tservice=smtp\t%srip=%s\tlip=%s\tnologin\tresp=%s\n",
+       VERSION_MAJOR, VERSION_MINOR, getpid(), crequid,
+       ablock->public_name, auth_extra_data, sender_host_address,
+       interface_address, data);
+
+if ((
+#ifndef DISABLE_TLS
+    cctx.tls_ctx ? tls_write(cctx.tls_ctx, auth_command, Ustrlen(auth_command), FALSE) :
+#endif
+    write(cctx.sock, auth_command, Ustrlen(auth_command))) < 0)
+  HDEBUG(D_auth) debug_printf("error sending auth_command: %s\n",
+    strerror(errno));
+
+HDEBUG(D_auth) debug_printf("sent: '%s'\n", auth_command);
+
+while (1)
+  {
+  uschar *temp;
+  uschar *auth_id_pre = NULL;
+
+  if (!dc_gets(buffer, sizeof(buffer), &cctx))
+    {
+    auth_defer_msg = US"authentication socket read error or premature eof";
+    goto out;
+    }
+
+  buffer[Ustrlen(buffer) - 1] = 0;
+  HDEBUG(D_auth) debug_printf("received: '%s'\n", buffer);
+  nargs = strcut(buffer, args, nelem(args));
+  HDEBUG(D_auth) debug_strcut(args, nargs, nelem(args));
+
+  if (Uatoi(args[1]) != crequid)
+    OUT("authentication socket connection id mismatch");
+
+  switch (toupper(*args[0]))
+    {
+    case 'C':
+      CHECK_COMMAND("CONT", 1, 2);
+
+      if ((tmp = auth_get_no64_data(&data, US args[2])) != OK)
+	{
+	ret = tmp;
+	goto out;
+	}
+
+      /* Added by PH: data must not contain tab (as it is
+      b64 it shouldn't, but check for safety). */
+
+      if (Ustrchr(data, '\t') != NULL)
+        {
+	ret = FAIL;
+	goto out;
+	}
+
+      temp = string_sprintf("CONT\t%d\t%s\n", crequid, data);
+      if ((
+#ifndef DISABLE_TLS
+	  cctx.tls_ctx ? tls_write(cctx.tls_ctx, temp, Ustrlen(temp), FALSE) :
+#endif
+	  write(cctx.sock, temp, Ustrlen(temp))) < 0)
+	OUT("authentication socket write error");
+      break;
+
+    case 'F':
+      CHECK_COMMAND("FAIL", 1, -1);
+
+      for (int i = 2; i < nargs && !auth_id_pre; i++)
+	if (Ustrncmp(args[i], US"user=", 5) == 0)
+	  {
+	  auth_id_pre = args[i] + 5;
+	  expand_nstring[1] = auth_vars[0] = string_copy(auth_id_pre); /* PH */
+	  expand_nlength[1] = Ustrlen(auth_id_pre);
+	  expand_nmax = 1;
+	  }
+      ret = FAIL;
+      goto out;
+
+    case 'O':
+      CHECK_COMMAND("OK", 2, -1);
+
+      /* Search for the "user=$USER" string in the args array
+      and return the proper value.  */
+
+      for (int i = 2; i < nargs && !auth_id_pre; i++)
+	if (Ustrncmp(args[i], US"user=", 5) == 0)
+	  {
+	  auth_id_pre = args[i] + 5;
+	  expand_nstring[1] = auth_vars[0] = string_copy(auth_id_pre); /* PH */
+	  expand_nlength[1] = Ustrlen(auth_id_pre);
+	  expand_nmax = 1;
+	  }
+
+      if (!auth_id_pre)
+        OUT("authentication socket protocol error, username missing");
+
+      auth_defer_msg = NULL;
+      ret = OK;
+      /* fallthrough */
+
+    default:
+      goto out;
+    }
+  }
+
+out:
+/* close the socket used by dovecot */
+#ifndef DISABLE_TLS
+if (cctx.tls_ctx)
+  tls_close(cctx.tls_ctx, TRUE);
+#endif
+if (cctx.sock >= 0)
+  close(cctx.sock);
+
+/* Expand server_condition as an authorization check */
+return ret == OK ? auth_check_serv_cond(ablock) : ret;
+}
+
+
+#endif   /*!MACRO_PREDEF*/
diff --git a/src/auths/dovecot.h b/src/auths/dovecot.h
new file mode 100644
index 0000000..bfe1f07
--- /dev/null
+++ b/src/auths/dovecot.h
@@ -0,0 +1,30 @@
+/*************************************************
+*     Exim - an Internet mail transport agent    *
+*************************************************/
+
+/* Copyright (c) University of Cambridge 1995 - 2009 */
+/* Copyright (c) The Exim Maintainters 2020 */
+/* See the file NOTICE for conditions of use and distribution. */
+
+/* Private structure for the private options. */
+
+typedef struct {
+  uschar *	server_socket;
+  BOOL		server_tls;
+} auth_dovecot_options_block;
+
+/* Data for reading the private options. */
+
+extern optionlist auth_dovecot_options[];
+extern int auth_dovecot_options_count;
+
+/* Block containing default values. */
+
+extern auth_dovecot_options_block auth_dovecot_option_defaults;
+
+/* The entry points for the mechanism */
+
+extern void auth_dovecot_init(auth_instance *);
+extern int auth_dovecot_server(auth_instance *, uschar *);
+
+/* End of dovecot.h */
diff --git a/src/auths/external.c b/src/auths/external.c
new file mode 100644
index 0000000..7e7fca8
--- /dev/null
+++ b/src/auths/external.c
@@ -0,0 +1,155 @@
+/*************************************************
+*     Exim - an Internet mail transport agent    *
+*************************************************/
+
+/* Copyright (c) Jeremy Harris 2019-2020 */
+/* See the file NOTICE for conditions of use and distribution. */
+
+/* This file provides an Exim authenticator driver for
+a server to verify a client SSL certificate, using the EXTERNAL
+method defined in RFC 4422 Appendix A.
+*/
+
+
+#include "../exim.h"
+#include "external.h"
+
+/* Options specific to the external authentication mechanism. */
+
+optionlist auth_external_options[] = {
+  { "client_send",	opt_stringptr, OPT_OFF(auth_external_options_block, client_send) },
+  { "server_param2",	opt_stringptr, OPT_OFF(auth_external_options_block, server_param2) },
+  { "server_param3",	opt_stringptr, OPT_OFF(auth_external_options_block, server_param3) },
+};
+
+/* Size of the options list. An extern variable has to be used so that its
+address can appear in the tables drtables.c. */
+
+int auth_external_options_count = nelem(auth_external_options);
+
+/* Default private options block for the authentication method. */
+
+auth_external_options_block auth_external_option_defaults = {
+    .server_param2 = NULL,
+    .server_param3 = NULL,
+
+    .client_send = NULL,
+};
+
+
+#ifdef MACRO_PREDEF
+
+/* Dummy values */
+void auth_external_init(auth_instance *ablock) {}
+int auth_external_server(auth_instance *ablock, uschar *data) {return 0;}
+int auth_external_client(auth_instance *ablock, void * sx,
+  int timeout, uschar *buffer, int buffsize) {return 0;}
+
+#else   /*!MACRO_PREDEF*/
+
+
+
+
+/*************************************************
+*          Initialization entry point            *
+*************************************************/
+
+/* Called for each instance, after its options have been read, to
+enable consistency checks to be done, or anything else that needs
+to be set up. */
+
+void
+auth_external_init(auth_instance *ablock)
+{
+auth_external_options_block * ob = (auth_external_options_block *)ablock->options_block;
+if (!ablock->public_name) ablock->public_name = ablock->name;
+if (ablock->server_condition) ablock->server = TRUE;
+if (ob->client_send) ablock->client = TRUE;
+}
+
+
+
+/*************************************************
+*             Server entry point                 *
+*************************************************/
+
+/* For interface, see auths/README */
+
+int
+auth_external_server(auth_instance * ablock, uschar * data)
+{
+auth_external_options_block * ob = (auth_external_options_block *)ablock->options_block;
+int rc;
+
+/* If data was supplied on the AUTH command, decode it, and split it up into
+multiple items at binary zeros. The strings are put into $auth1, $auth2, etc,
+up to a maximum. To retain backwards compatibility, they are also put int $1,
+$2, etc. If the data consists of the string "=" it indicates a single, empty
+string. */
+
+if (*data)
+  if ((rc = auth_read_input(data)) != OK)
+    return rc;
+
+/* Now go through the list of prompt strings. Skip over any whose data has
+already been provided as part of the AUTH command. For the rest, send them
+out as prompts, and get a data item back. If the data item is "*", abandon the
+authentication attempt. Otherwise, split it into items as above. */
+
+if (expand_nmax == 0) 	/* skip if rxd data */
+  if ((rc = auth_prompt(CUS"")) != OK)
+    return rc;
+
+if (ob->server_param2)
+  {
+  uschar * s = expand_string(ob->server_param2);
+  auth_vars[expand_nmax] = s;
+  expand_nstring[++expand_nmax] = s;
+  expand_nlength[expand_nmax] = Ustrlen(s);
+  if (ob->server_param3)
+    {
+    s = expand_string(ob->server_param3);
+    auth_vars[expand_nmax] = s;
+    expand_nstring[++expand_nmax] = s;
+    expand_nlength[expand_nmax] = Ustrlen(s);
+    }
+  }
+
+return auth_check_serv_cond(ablock);
+}
+
+
+
+/*************************************************
+*              Client entry point                *
+*************************************************/
+
+/* For interface, see auths/README */
+
+int
+auth_external_client(
+  auth_instance *ablock,                 /* authenticator block */
+  void * sx,				 /* smtp connextion */
+  int timeout,                           /* command timeout */
+  uschar *buffer,                        /* buffer for reading response */
+  int buffsize)                          /* size of buffer */
+{
+auth_external_options_block *ob =
+  (auth_external_options_block *)(ablock->options_block);
+const uschar * text = ob->client_send;
+int rc;
+
+/* We output an AUTH command with one expanded argument, the client_send option */
+
+if ((rc = auth_client_item(sx, ablock, &text, AUTH_ITEM_FIRST | AUTH_ITEM_LAST,
+      timeout, buffer, buffsize)) != OK)
+  return rc == DEFER ? FAIL : rc;
+
+if (text) auth_vars[0] = string_copy(text);
+return OK;
+}
+
+
+
+#endif   /*!MACRO_PREDEF*/
+/* End of external.c */
diff --git a/src/auths/external.h b/src/auths/external.h
new file mode 100644
index 0000000..7d43650
--- /dev/null
+++ b/src/auths/external.h
@@ -0,0 +1,32 @@
+/*************************************************
+*     Exim - an Internet mail transport agent    *
+*************************************************/
+
+/* Copyright (c) Jeremy Harris 2019 */
+/* See the file NOTICE for conditions of use and distribution. */
+
+/* Private structure for the private options. */
+
+typedef struct {
+  uschar * server_param2;
+  uschar * server_param3;
+
+  uschar * client_send;
+} auth_external_options_block;
+
+/* Data for reading the private options. */
+
+extern optionlist auth_external_options[];
+extern int auth_external_options_count;
+
+/* Block containing default values. */
+
+extern auth_external_options_block auth_external_option_defaults;
+
+/* The entry points for the mechanism */
+
+extern void auth_external_init(auth_instance *);
+extern int auth_external_server(auth_instance *, uschar *);
+extern int auth_external_client(auth_instance *, void *, int, uschar *, int);
+
+/* End of external.h */
diff --git a/src/auths/get_data.c b/src/auths/get_data.c
new file mode 100644
index 0000000..8835965
--- /dev/null
+++ b/src/auths/get_data.c
@@ -0,0 +1,259 @@
+/*************************************************
+*     Exim - an Internet mail transport agent    *
+*************************************************/
+
+/* Copyright (c) University of Cambridge 1995 - 2018 */
+/* Copyright (c) The Exim Maintainers 2020 */
+/* See the file NOTICE for conditions of use and distribution. */
+
+#include "../exim.h"
+
+
+/****************************************************************
+*	Decode and split the argument of an AUTH command	*
+****************************************************************/
+
+/* If data was supplied on the AUTH command, decode it, and split it up into
+multiple items at binary zeros. The strings are put into $auth1, $auth2, etc,
+up to a maximum. To retain backwards compatibility, they are also put int $1,
+$2, etc. If the data consists of the string "=" it indicates a single, empty
+string. */
+
+int
+auth_read_input(const uschar * data)
+{
+if (Ustrcmp(data, "=") == 0)
+  {
+  auth_vars[0] = expand_nstring[++expand_nmax] = US"";
+  expand_nlength[expand_nmax] = 0;
+  }
+else
+  {
+  uschar * clear, * end;
+  int len;
+
+  if ((len = b64decode(data, &clear)) < 0) return BAD64;
+  DEBUG(D_auth) debug_printf("auth input decode:");
+  for (end = clear + len; clear < end && expand_nmax < EXPAND_MAXN; )
+    {
+    DEBUG(D_auth) debug_printf(" '%s'", clear);
+    if (expand_nmax < AUTH_VARS) auth_vars[expand_nmax] = clear;
+    expand_nstring[++expand_nmax] = clear;
+    while (*clear != 0) clear++;
+    expand_nlength[expand_nmax] = clear++ - expand_nstring[expand_nmax];
+    }
+  DEBUG(D_auth) debug_printf("\n");
+  }
+return OK;
+}
+
+
+
+
+/*************************************************
+*      Issue a challenge and get a response      *
+*************************************************/
+
+/* This function is used by authentication drivers to b64-encode and
+output a challenge to the SMTP client, and read the response line.
+
+Arguments:
+   aptr       set to point to the response (which is in big_buffer)
+   challenge  the challenge data (unencoded, may be binary)
+   challen    the length of the challenge data, in bytes
+
+Returns:      OK on success
+              BAD64 if response too large for buffer
+              CANCELLED if response is "*"
+*/
+
+int
+auth_get_data(uschar ** aptr, const uschar * challenge, int challen)
+{
+int c;
+int p = 0;
+smtp_printf("334 %s\r\n", FALSE, b64encode(challenge, challen));
+while ((c = receive_getc(GETC_BUFFER_UNLIMITED)) != '\n' && c != EOF)
+  {
+  if (p >= big_buffer_size - 1) return BAD64;
+  big_buffer[p++] = c;
+  }
+if (p > 0 && big_buffer[p-1] == '\r') p--;
+big_buffer[p] = 0;
+DEBUG(D_receive) debug_printf("SMTP<< %s\n", big_buffer);
+if (Ustrcmp(big_buffer, "*") == 0) return CANCELLED;
+*aptr = big_buffer;
+return OK;
+}
+
+
+
+int
+auth_prompt(const uschar * challenge)
+{
+int rc, len;
+uschar * resp, * clear, * end;
+
+if ((rc = auth_get_data(&resp, challenge, Ustrlen(challenge))) != OK)
+  return rc;
+if ((len = b64decode(resp, &clear)) < 0)
+  return BAD64;
+end = clear + len;
+
+/* This loop must run at least once, in case the length is zero */
+do
+  {
+  if (expand_nmax < AUTH_VARS) auth_vars[expand_nmax] = clear;
+  expand_nstring[++expand_nmax] = clear;
+  while (*clear != 0) clear++;
+  expand_nlength[expand_nmax] = clear++ - expand_nstring[expand_nmax];
+  }
+while (clear < end && expand_nmax < EXPAND_MAXN);
+return OK;
+}
+
+
+/***********************************************
+*	Send an AUTH-negotiation item		*
+************************************************/
+
+/* Expand and send one client auth item and read the response.
+Include the AUTH command and method if tagged as "first".  Use the given buffer
+for receiving the b6-encoded reply; decode it it return it in the string arg.
+
+Return:
+  OK          success
+  FAIL_SEND   error after writing a command; errno is set
+  FAIL        failed after reading a response;
+              either errno is set (for timeouts, I/O failures) or
+              the buffer contains the SMTP response line
+  CANCELLED   the client cancelled authentication (often "fail" in expansion)
+              the buffer may contain a message; if not, *buffer = 0
+  ERROR       local problem (typically expansion error); message in buffer
+  DEFER       more items expected
+*/
+
+int
+auth_client_item(void * sx, auth_instance * ablock, const uschar ** inout,
+  unsigned flags, int timeout, uschar * buffer, int buffsize)
+{
+int len, clear_len;
+uschar * ss, * clear;
+
+ss = US expand_cstring(*inout);
+if (ss == *inout) ss = string_copy(ss);
+
+/* Forced expansion failure is not an error; authentication is abandoned. On
+all but the first string, we have to abandon the authentication attempt by
+sending a line containing "*". Save the failed expansion string, because it
+is in big_buffer, and that gets used by the sending function. */
+
+if (!ss)
+  {
+  if (!(flags & AUTH_ITEM_FIRST))
+    {
+    if (smtp_write_command(sx, SCMD_FLUSH, "*\r\n") >= 0)
+      (void) smtp_read_response(sx, US buffer, buffsize, '2', timeout);
+    }
+  if (f.expand_string_forcedfail)
+    {
+    *buffer = 0;       /* No message */
+    return CANCELLED;
+    }
+  string_format(buffer, buffsize, "expansion of \"%s\" failed in %s "
+    "authenticator: %s", *inout, ablock->name, expand_string_message);
+  return ERROR;
+  }
+
+len = Ustrlen(ss);
+
+/* The character ^ is used as an escape for a binary zero character, which is
+needed for the PLAIN mechanism. It must be doubled if really needed.
+
+The parsing ambiguity of ^^^ is taken as ^^ -> ^ ; ^ -> NUL - and there is
+no way to get a leading ^ after a NUL.  We would need to intro new syntax to
+support that (probably preferring to take a more-standard exim list as a source
+and concat the elements with intervening NULs.  Either a magic marker on the
+source string for client_send, or a new option). */
+
+for (int i = 0; i < len; i++)
+  if (ss[i] == '^')
+    if (ss[i+1] != '^')
+      ss[i] = 0;
+    else
+      if (--len > i+1) memmove(ss + i + 1, ss + i + 2, len - i);
+
+/* The first string is attached to the AUTH command; others are sent
+unembellished. */
+
+if (flags & AUTH_ITEM_FIRST)
+  {
+  if (smtp_write_command(sx, SCMD_FLUSH, "AUTH %s%s%s\r\n",
+       ablock->public_name, len == 0 ? "" : " ", b64encode(CUS ss, len)) < 0)
+    return FAIL_SEND;
+  }
+else
+  if (smtp_write_command(sx, SCMD_FLUSH, "%s\r\n", b64encode(CUS ss, len)) < 0)
+    return FAIL_SEND;
+
+/* If we receive a success response from the server, authentication
+has succeeded. There may be more data to send, but is there any point
+in provoking an error here? */
+
+if (smtp_read_response(sx, buffer, buffsize, '2', timeout))
+  {
+  *inout = NULL;
+  return OK;
+  }
+
+/* Not a success response. If errno != 0 there is some kind of transmission
+error. Otherwise, check the response code in the buffer. If it starts with
+'3', more data is expected. */
+
+if (errno != 0 || buffer[0] != '3') return FAIL;
+
+/* If there is no more data to send, we have to cancel the authentication
+exchange and return ERROR. */
+
+if (flags & AUTH_ITEM_LAST)
+  {
+  if (smtp_write_command(sx, SCMD_FLUSH, "*\r\n") >= 0)
+    (void)smtp_read_response(sx, US buffer, buffsize, '2', timeout);
+  string_format(buffer, buffsize, "Too few items in client_send in %s "
+    "authenticator", ablock->name);
+  return ERROR;
+  }
+
+/* Now that we know we'll continue, we put the received data into $auth<n>,
+if possible. First, decode it: buffer+4 skips over the SMTP status code. */
+
+clear_len = b64decode(buffer+4, &clear);
+
+/* If decoding failed, the default is to terminate the authentication, and
+return FAIL, with the SMTP response still in the buffer. However, if client_
+ignore_invalid_base64 is set, we ignore the error, and put an empty string
+into $auth<n>. */
+
+if (clear_len < 0)
+  {
+  uschar *save_bad = string_copy(buffer);
+  if (!(flags & AUTH_ITEM_IGN64))
+    {
+    if (smtp_write_command(sx, SCMD_FLUSH, "*\r\n") >= 0)
+      (void)smtp_read_response(sx, US buffer, buffsize, '2', timeout);
+    string_format(buffer, buffsize, "Invalid base64 string in server "
+      "response \"%s\"", save_bad);
+    return CANCELLED;
+    }
+  DEBUG(D_auth) debug_printf("bad b64 decode for '%s';"
+       " ignoring due to client_ignore_invalid_base64\n", save_bad);
+  clear = string_copy(US"");
+  clear_len = 0;
+  }
+
+*inout = clear;
+return DEFER;
+}
+  
+  
+/* End of get_data.c */
diff --git a/src/auths/get_no64_data.c b/src/auths/get_no64_data.c
new file mode 100644
index 0000000..a019756
--- /dev/null
+++ b/src/auths/get_no64_data.c
@@ -0,0 +1,47 @@
+/*************************************************
+*     Exim - an Internet mail transport agent    *
+*************************************************/
+
+/* Copyright (c) University of Cambridge 1995 - 2018 */
+/* See the file NOTICE for conditions of use and distribution. */
+
+#include "../exim.h"
+
+
+/*************************************************
+*  Issue a non-b64 challenge and get a response  *
+*************************************************/
+
+/* This function is used by authentication drivers to output a challenge
+to the SMTP client and read the response line. This version does not use base
+64 encoding for the text on the 334 line. It is used by the SPA, dovecot
+and gsasl authenticators.
+
+Arguments:
+   aptr       set to point to the response (which is in big_buffer)
+   challenge  the challenge text (unencoded)
+
+Returns:      OK on success
+              BAD64 if response too large for buffer
+              CANCELLED if response is "*"
+*/
+
+int
+auth_get_no64_data(uschar **aptr, uschar *challenge)
+{
+int c;
+int p = 0;
+smtp_printf("334 %s\r\n", FALSE, challenge);
+while ((c = receive_getc(GETC_BUFFER_UNLIMITED)) != '\n' && c != EOF)
+  {
+  if (p >= big_buffer_size - 1) return BAD64;
+  big_buffer[p++] = c;
+  }
+if (p > 0 && big_buffer[p-1] == '\r') p--;
+big_buffer[p] = 0;
+if (Ustrcmp(big_buffer, "*") == 0) return CANCELLED;
+*aptr = big_buffer;
+return OK;
+}
+
+/* End of get_no64_data.c */
diff --git a/src/auths/gsasl_exim.c b/src/auths/gsasl_exim.c
new file mode 100644
index 0000000..a3aaf1f
--- /dev/null
+++ b/src/auths/gsasl_exim.c
@@ -0,0 +1,982 @@
+/*************************************************
+*     Exim - an Internet mail transport agent    *
+*************************************************/
+
+/* Copyright (c) The Exim Maintainers 2019-2020 */
+/* Copyright (c) University of Cambridge 1995 - 2018 */
+/* See the file NOTICE for conditions of use and distribution. */
+
+/* Copyright (c) Twitter Inc 2012
+   Author: Phil Pennock <pdp@exim.org> */
+/* Copyright (c) Phil Pennock 2012 */
+
+/* Interface to GNU SASL library for generic authentication. */
+
+/* Trade-offs:
+
+GNU SASL does not provide authentication data itself, so we have to expose
+that decision to configuration.  For some mechanisms, we need to act much
+like plaintext.  For others, we only need to be able to provide some
+evaluated data on demand.  There's no abstracted way (ie, without hardcoding
+knowledge of authenticators here) to know which need what properties; we
+can't query a session or the library for "we will need these for mechanism X".
+
+So: we always require server_condition, even if sometimes it will just be
+set as "yes".  We do provide a number of other hooks, which might not make
+sense in all contexts.  For some, we can do checks at init time.
+*/
+
+#include "../exim.h"
+#define CHANNELBIND_HACK
+
+#ifndef AUTH_GSASL
+/* dummy function to satisfy compilers when we link in an "empty" file. */
+static void dummy(int x);
+static void dummy2(int x) { dummy(x-1); }
+static void dummy(int x) { dummy2(x-1); }
+#else
+
+#include <gsasl.h>
+#include "gsasl_exim.h"
+
+
+#if GSASL_VERSION_MINOR >= 9
+# define EXIM_GSASL_HAVE_SCRAM_SHA_256
+
+# if GSASL_VERSION_PATCH >= 1
+#  define EXIM_GSASL_SCRAM_S_KEY
+# endif
+#endif
+
+
+/* Authenticator-specific options. */
+/* I did have server_*_condition options for various mechanisms, but since
+we only ever handle one mechanism at a time, I didn't see the point in keeping
+that.  In case someone sees a point, I've left the condition_check() API
+alone. */
+#define LOFF(field) OPT_OFF(auth_gsasl_options_block, field)
+
+optionlist auth_gsasl_options[] = {
+  { "client_authz",		opt_stringptr,	LOFF(client_authz) },
+  { "client_channelbinding",	opt_bool,	LOFF(client_channelbinding) },
+  { "client_password",		opt_stringptr,	LOFF(client_password) },
+  { "client_spassword",		opt_stringptr,	LOFF(client_spassword) },
+  { "client_username",		opt_stringptr,	LOFF(client_username) },
+
+  { "server_channelbinding",	opt_bool,	LOFF(server_channelbinding) },
+  { "server_hostname",		opt_stringptr,	LOFF(server_hostname) },
+#ifdef EXIM_GSASL_SCRAM_S_KEY
+  { "server_key",		opt_stringptr,	LOFF(server_key) },
+#endif
+  { "server_mech",		opt_stringptr,	LOFF(server_mech) },
+  { "server_password",		opt_stringptr,	LOFF(server_password) },
+  { "server_realm",		opt_stringptr,	LOFF(server_realm) },
+  { "server_scram_iter",	opt_stringptr,	LOFF(server_scram_iter) },
+  { "server_scram_salt",	opt_stringptr,	LOFF(server_scram_salt) },
+#ifdef EXIM_GSASL_SCRAM_S_KEY
+  { "server_skey",		opt_stringptr,	LOFF(server_s_key) },
+#endif
+  { "server_service",		opt_stringptr,	LOFF(server_service) }
+};
+
+int auth_gsasl_options_count =
+  sizeof(auth_gsasl_options)/sizeof(optionlist);
+
+/* Defaults for the authenticator-specific options. */
+auth_gsasl_options_block auth_gsasl_option_defaults = {
+  .server_service = US"smtp",
+  .server_hostname = US"$primary_hostname",
+  .server_scram_iter = US"4096",
+  /* all others zero/null */
+};
+
+
+#ifdef MACRO_PREDEF
+# include "../macro_predef.h"
+
+/* Dummy values */
+void auth_gsasl_init(auth_instance *ablock) {}
+int auth_gsasl_server(auth_instance *ablock, uschar *data) {return 0;}
+int auth_gsasl_client(auth_instance *ablock, void * sx,
+  int timeout, uschar *buffer, int buffsize) {return 0;}
+void auth_gsasl_version_report(FILE *f) {}
+
+void
+auth_gsasl_macros(void)
+{
+# ifdef EXIM_GSASL_HAVE_SCRAM_SHA_256
+  builtin_macro_create(US"_HAVE_AUTH_GSASL_SCRAM_SHA_256");
+# endif
+# ifdef EXIM_GSASL_SCRAM_S_KEY
+  builtin_macro_create(US"_HAVE_AUTH_GSASL_SCRAM_S_KEY");
+# endif
+}
+
+#else   /*!MACRO_PREDEF*/
+
+
+
+/* "Globals" for managing the gsasl interface. */
+
+static Gsasl *gsasl_ctx = NULL;
+static int
+  main_callback(Gsasl *ctx, Gsasl_session *sctx, Gsasl_property prop);
+static int
+  server_callback(Gsasl *ctx, Gsasl_session *sctx, Gsasl_property prop, auth_instance *ablock);
+static int
+  client_callback(Gsasl *ctx, Gsasl_session *sctx, Gsasl_property prop, auth_instance *ablock);
+
+static BOOL sasl_error_should_defer = FALSE;
+static Gsasl_property callback_loop = 0;
+static BOOL checked_server_condition = FALSE;
+
+enum { CURRENTLY_SERVER = 1, CURRENTLY_CLIENT = 2 };
+
+struct callback_exim_state {
+  auth_instance *ablock;
+  int currently;
+};
+
+
+/*************************************************
+*          Initialization entry point            *
+*************************************************/
+
+/* Called for each instance, after its options have been read, to
+enable consistency checks to be done, or anything else that needs
+to be set up. */
+
+void
+auth_gsasl_init(auth_instance *ablock)
+{
+static char * once = NULL;
+int rc;
+auth_gsasl_options_block *ob =
+  (auth_gsasl_options_block *)(ablock->options_block);
+
+/* As per existing Cyrus glue, use the authenticator's public name as
+the default for the mechanism name; we don't handle multiple mechanisms
+in one authenticator, but the same driver can be used multiple times. */
+
+if (!ob->server_mech)
+  ob->server_mech = string_copy(ablock->public_name);
+
+/* Can get multiple session contexts from one library context, so just
+initialise the once. */
+
+if (!gsasl_ctx)
+  {
+  if ((rc = gsasl_init(&gsasl_ctx)) != GSASL_OK)
+    log_write(0, LOG_PANIC_DIE|LOG_CONFIG_FOR, "%s authenticator:  "
+	      "couldn't initialise GNU SASL library: %s (%s)",
+	      ablock->name, gsasl_strerror_name(rc), gsasl_strerror(rc));
+
+  gsasl_callback_set(gsasl_ctx, main_callback);
+  }
+
+/* We don't need this except to log it for debugging. */
+
+HDEBUG(D_auth) if (!once)
+  {
+  if ((rc = gsasl_server_mechlist(gsasl_ctx, &once)) != GSASL_OK)
+    log_write(0, LOG_PANIC_DIE|LOG_CONFIG_FOR, "%s authenticator:  "
+	      "failed to retrieve list of mechanisms: %s (%s)",
+	      ablock->name,  gsasl_strerror_name(rc), gsasl_strerror(rc));
+
+  debug_printf("GNU SASL supports: %s\n", once);
+  }
+
+if (!gsasl_client_support_p(gsasl_ctx, CCS ob->server_mech))
+  log_write(0, LOG_PANIC_DIE|LOG_CONFIG_FOR, "%s authenticator:  "
+	    "GNU SASL does not support mechanism \"%s\"",
+	    ablock->name, ob->server_mech);
+
+ablock->server = TRUE;
+
+if (  !ablock->server_condition
+   && (  streqic(ob->server_mech, US"EXTERNAL")
+      || streqic(ob->server_mech, US"ANONYMOUS")
+      || streqic(ob->server_mech, US"PLAIN")
+      || streqic(ob->server_mech, US"LOGIN")
+   )  )
+  {
+  ablock->server = FALSE;
+  HDEBUG(D_auth) debug_printf("%s authenticator:  "
+	    "Need server_condition for %s mechanism\n",
+	    ablock->name, ob->server_mech);
+  }
+
+/* This does *not* scale to new SASL mechanisms.  Need a better way to ask
+which properties will be needed. */
+
+if (  !ob->server_realm
+   && streqic(ob->server_mech, US"DIGEST-MD5"))
+  {
+  ablock->server = FALSE;
+  HDEBUG(D_auth) debug_printf("%s authenticator:  "
+	    "Need server_realm for %s mechanism\n",
+	    ablock->name, ob->server_mech);
+  }
+
+/* At present, for mechanisms we don't panic on absence of server_condition;
+need to figure out the most generically correct approach to deciding when
+it's critical and when it isn't.  Eg, for simple validation (PLAIN mechanism,
+etc) it clearly is critical.
+*/
+
+ablock->client = ob->client_username && ob->client_password;
+}
+
+
+/* GNU SASL uses one top-level callback, registered at library level.
+We dispatch to client and server functions instead. */
+
+static int
+main_callback(Gsasl *ctx, Gsasl_session *sctx, Gsasl_property prop)
+{
+int rc = 0;
+struct callback_exim_state *cb_state =
+  (struct callback_exim_state *)gsasl_session_hook_get(sctx);
+
+if (!cb_state)
+  {
+  HDEBUG(D_auth) debug_printf("gsasl callback (%d) not from our server/client processing\n", prop);
+#ifdef CHANNELBIND_HACK
+  if (prop == GSASL_CB_TLS_UNIQUE)
+    {
+    uschar * s;
+    if ((s = gsasl_callback_hook_get(ctx)))
+      {
+      HDEBUG(D_auth) debug_printf("GSASL_CB_TLS_UNIQUE from ctx hook\n");
+      gsasl_property_set(sctx, GSASL_CB_TLS_UNIQUE, CS s);
+      }
+    else
+      {
+      HDEBUG(D_auth) debug_printf("GSASL_CB_TLS_UNIQUE!  dummy for now\n");
+      gsasl_property_set(sctx, GSASL_CB_TLS_UNIQUE, "");
+      }
+    return GSASL_OK;
+    }
+#endif
+  return GSASL_NO_CALLBACK;
+  }
+
+HDEBUG(D_auth)
+  debug_printf("GNU SASL Callback entered, prop=%d (loop prop=%d)\n",
+      prop, callback_loop);
+
+if (callback_loop > 0)
+  {
+  /* Most likely is that we were asked for property FOO, and to
+  expand the string we asked for property BAR to put into an auth
+  variable, but property BAR is not supplied for this mechanism. */
+  HDEBUG(D_auth)
+    debug_printf("Loop, asked for property %d while handling property %d\n",
+	prop, callback_loop);
+  return GSASL_NO_CALLBACK;
+  }
+callback_loop = prop;
+
+if (cb_state->currently == CURRENTLY_CLIENT)
+  rc = client_callback(ctx, sctx, prop, cb_state->ablock);
+else if (cb_state->currently == CURRENTLY_SERVER)
+  rc = server_callback(ctx, sctx, prop, cb_state->ablock);
+else
+  log_write(0, LOG_PANIC_DIE|LOG_CONFIG_FOR, "%s authenticator:  "
+      "unhandled callback state, bug in Exim", cb_state->ablock->name);
+  /* NOTREACHED */
+
+callback_loop = 0;
+return rc;
+}
+
+
+/*************************************************
+*             Debug service function             *
+*************************************************/
+static const uschar * 
+gsasl_prop_code_to_name(Gsasl_property prop)
+{
+switch (prop)
+  {
+  case GSASL_AUTHID: return US"AUTHID";
+  case GSASL_AUTHZID: return US"AUTHZID";
+  case GSASL_PASSWORD: return US"PASSWORD";
+  case GSASL_ANONYMOUS_TOKEN: return US"ANONYMOUS_TOKEN";
+  case GSASL_SERVICE: return US"SERVICE";
+  case GSASL_HOSTNAME: return US"HOSTNAME";
+  case GSASL_GSSAPI_DISPLAY_NAME: return US"GSSAPI_DISPLAY_NAME";
+  case GSASL_PASSCODE: return US"PASSCODE";
+  case GSASL_SUGGESTED_PIN: return US"SUGGESTED_PIN";
+  case GSASL_PIN: return US"PIN";
+  case GSASL_REALM: return US"REALM";
+  case GSASL_DIGEST_MD5_HASHED_PASSWORD: return US"DIGEST_MD5_HASHED_PASSWORD";
+  case GSASL_QOPS: return US"QOPS";
+  case GSASL_QOP: return US"QOP";
+  case GSASL_SCRAM_ITER: return US"SCRAM_ITER";
+  case GSASL_SCRAM_SALT: return US"SCRAM_SALT";
+  case GSASL_SCRAM_SALTED_PASSWORD: return US"SCRAM_SALTED_PASSWORD";
+#ifdef EXIM_GSASL_SCRAM_S_KEY
+  case GSASL_SCRAM_STOREDKEY: return US"SCRAM_STOREDKEY";
+  case GSASL_SCRAM_SERVERKEY: return US"SCRAM_SERVERKEY";
+#endif
+  case GSASL_CB_TLS_UNIQUE: return US"CB_TLS_UNIQUE";
+  case GSASL_SAML20_IDP_IDENTIFIER: return US"SAML20_IDP_IDENTIFIER";
+  case GSASL_SAML20_REDIRECT_URL: return US"SAML20_REDIRECT_URL";
+  case GSASL_OPENID20_REDIRECT_URL: return US"OPENID20_REDIRECT_URL";
+  case GSASL_OPENID20_OUTCOME_DATA: return US"OPENID20_OUTCOME_DATA";
+  case GSASL_SAML20_AUTHENTICATE_IN_BROWSER: return US"SAML20_AUTHENTICATE_IN_BROWSER";
+  case GSASL_OPENID20_AUTHENTICATE_IN_BROWSER: return US"OPENID20_AUTHENTICATE_IN_BROWSER";
+#ifdef EXIM_GSASL_SCRAM_S_KEY
+  case GSASL_SCRAM_CLIENTKEY: return US"SCRAM_CLIENTKEY";
+#endif
+  case GSASL_VALIDATE_SIMPLE: return US"VALIDATE_SIMPLE";
+  case GSASL_VALIDATE_EXTERNAL: return US"VALIDATE_EXTERNAL";
+  case GSASL_VALIDATE_ANONYMOUS: return US"VALIDATE_ANONYMOUS";
+  case GSASL_VALIDATE_GSSAPI: return US"VALIDATE_GSSAPI";
+  case GSASL_VALIDATE_SECURID: return US"VALIDATE_SECURID";
+  case GSASL_VALIDATE_SAML20: return US"VALIDATE_SAML20";
+  case GSASL_VALIDATE_OPENID20: return US"VALIDATE_OPENID20";
+  }
+return CUS string_sprintf("(unknown prop: %d)", (int)prop);
+}
+
+/*************************************************
+*             Server entry point                 *
+*************************************************/
+
+/* For interface, see auths/README */
+
+int
+auth_gsasl_server(auth_instance *ablock, uschar *initial_data)
+{
+char *tmps;
+char *to_send, *received;
+Gsasl_session *sctx = NULL;
+auth_gsasl_options_block *ob =
+  (auth_gsasl_options_block *)(ablock->options_block);
+struct callback_exim_state cb_state;
+int rc, auth_result, exim_error, exim_error_override;
+
+HDEBUG(D_auth)
+  debug_printf("GNU SASL: initialising session for %s, mechanism %s\n",
+      ablock->name, ob->server_mech);
+
+#ifndef DISABLE_TLS
+if (tls_in.channelbinding && ob->server_channelbinding)
+  {
+# ifdef EXPERIMENTAL_TLS_RESUME
+  if (!tls_in.ext_master_secret && tls_in.resumption == RESUME_USED)
+    {		/* per RFC 7677 section 4 */
+    HDEBUG(D_auth) debug_printf(
+      "channel binding not usable on resumed TLS without extended-master-secret");
+    return FAIL;
+    }
+# endif
+# ifdef CHANNELBIND_HACK
+/* This is a gross hack to get around the library a) requiring that
+c-b was already set, at the _start() call, and b) caching a b64'd
+version of the binding then which it never updates. */
+
+  gsasl_callback_hook_set(gsasl_ctx, tls_in.channelbinding);
+# endif
+  }
+#endif
+
+if ((rc = gsasl_server_start(gsasl_ctx, CCS ob->server_mech, &sctx)) != GSASL_OK)
+  {
+  auth_defer_msg = string_sprintf("GNU SASL: session start failure: %s (%s)",
+      gsasl_strerror_name(rc), gsasl_strerror(rc));
+  HDEBUG(D_auth) debug_printf("%s\n", auth_defer_msg);
+  return DEFER;
+  }
+/* Hereafter: gsasl_finish(sctx) please */
+
+cb_state.ablock = ablock;
+cb_state.currently = CURRENTLY_SERVER;
+gsasl_session_hook_set(sctx, &cb_state);
+
+tmps = CS expand_string(ob->server_service);
+gsasl_property_set(sctx, GSASL_SERVICE, tmps);
+tmps = CS expand_string(ob->server_hostname);
+gsasl_property_set(sctx, GSASL_HOSTNAME, tmps);
+if (ob->server_realm)
+  {
+  tmps = CS expand_string(ob->server_realm);
+  if (tmps && *tmps)
+    gsasl_property_set(sctx, GSASL_REALM, tmps);
+  }
+/* We don't support protection layers. */
+gsasl_property_set(sctx, GSASL_QOPS, "qop-auth");
+
+#ifndef DISABLE_TLS
+if (tls_in.channelbinding)
+  {
+  /* Some auth mechanisms can ensure that both sides are talking withing the
+  same security context; for TLS, this means that even if a bad certificate
+  has been accepted, they remain MitM-proof because both sides must be within
+  the same negotiated session; if someone is terminating one session and
+  proxying data on within a second, authentication will fail.
+
+  We might not have this available, depending upon TLS implementation,
+  ciphersuite, phase of moon ...
+
+  If we do, it results in extra SASL mechanisms being available; here,
+  Exim's one-mechanism-per-authenticator potentially causes problems.
+  It depends upon how GNU SASL will implement the PLUS variants of GS2
+  and whether it automatically mandates a switch to the bound PLUS
+  if the data is available.  Since default-on, despite being more secure,
+  would then result in mechanism name changes on a library update, we
+  have little choice but to default it off and let the admin choose to
+  enable it.  *sigh*
+  */
+  if (ob->server_channelbinding)
+    {
+    HDEBUG(D_auth) debug_printf("Auth %s: Enabling channel-binding\n",
+	ablock->name);
+# ifndef CHANNELBIND_HACK
+    gsasl_property_set(sctx, GSASL_CB_TLS_UNIQUE, CCS tls_in.channelbinding);
+# endif
+    }
+  else
+    HDEBUG(D_auth)
+      debug_printf("Auth %s: Not enabling channel-binding (data available)\n",
+	  ablock->name);
+  }
+else
+  HDEBUG(D_auth)
+    debug_printf("Auth %s: no channel-binding data available\n",
+	ablock->name);
+#endif
+
+checked_server_condition = FALSE;
+
+received = CS initial_data;
+to_send = NULL;
+exim_error = exim_error_override = OK;
+
+do {
+  switch (rc = gsasl_step64(sctx, received, &to_send))
+    {
+    case GSASL_OK:
+      if (!to_send)
+	goto STOP_INTERACTION;
+      break;
+
+    case GSASL_NEEDS_MORE:
+      break;
+
+    case GSASL_AUTHENTICATION_ERROR:
+    case GSASL_INTEGRITY_ERROR:
+    case GSASL_NO_AUTHID:
+    case GSASL_NO_ANONYMOUS_TOKEN:
+    case GSASL_NO_AUTHZID:
+    case GSASL_NO_PASSWORD:
+    case GSASL_NO_PASSCODE:
+    case GSASL_NO_PIN:
+    case GSASL_BASE64_ERROR:
+      HDEBUG(D_auth) debug_printf("GNU SASL permanent error: %s (%s)\n",
+	  gsasl_strerror_name(rc), gsasl_strerror(rc));
+      log_write(0, LOG_REJECT, "%s authenticator (%s):\n  "
+	  "GNU SASL permanent failure: %s (%s)",
+	  ablock->name, ob->server_mech,
+	  gsasl_strerror_name(rc), gsasl_strerror(rc));
+      if (rc == GSASL_BASE64_ERROR)
+	exim_error_override = BAD64;
+      goto STOP_INTERACTION;
+
+    default:
+      auth_defer_msg = string_sprintf("GNU SASL temporary error: %s (%s)",
+	  gsasl_strerror_name(rc), gsasl_strerror(rc));
+      HDEBUG(D_auth) debug_printf("%s\n", auth_defer_msg);
+      exim_error_override = DEFER;
+      goto STOP_INTERACTION;
+    }
+
+  /*XXX having our caller send the final smtp "235" is unfortunate; wastes a roundtrip */
+  if ((rc == GSASL_NEEDS_MORE) || (to_send && *to_send))
+    exim_error = auth_get_no64_data(USS &received, US to_send);
+
+  if (to_send)
+    {
+    free(to_send);
+    to_send = NULL;
+    }
+
+  if (exim_error)
+    break; /* handles * cancelled check */
+
+  } while (rc == GSASL_NEEDS_MORE);
+
+STOP_INTERACTION:
+auth_result = rc;
+
+HDEBUG(D_auth)
+  {
+  const uschar * s;
+  if ((s = CUS gsasl_property_fast(sctx, GSASL_SCRAM_ITER)))
+    debug_printf(" - itercnt:   '%s'\n", s);
+  if ((s = CUS gsasl_property_fast(sctx, GSASL_SCRAM_SALT)))
+    debug_printf(" - salt:      '%s'\n", s);
+#ifdef EXIM_GSASL_SCRAM_S_KEY
+  if ((s = CUS gsasl_property_fast(sctx, GSASL_SCRAM_SERVERKEY)))
+    debug_printf(" - ServerKey: '%s'\n", s);
+  if ((s = CUS gsasl_property_fast(sctx, GSASL_SCRAM_STOREDKEY)))
+    debug_printf(" - StoredKey: '%s'\n", s);
+#endif
+  }
+
+gsasl_finish(sctx);
+
+/* Can return: OK DEFER FAIL CANCELLED BAD64 UNEXPECTED */
+
+if (exim_error != OK)
+  return exim_error;
+
+if (auth_result != GSASL_OK)
+  {
+  HDEBUG(D_auth) debug_printf("authentication returned %s (%s)\n",
+      gsasl_strerror_name(auth_result), gsasl_strerror(auth_result));
+  if (exim_error_override != OK)
+    return exim_error_override; /* might be DEFER */
+  if (sasl_error_should_defer) /* overriding auth failure SASL error */
+    return DEFER;
+  return FAIL;
+  }
+
+/* Auth succeeded, check server_condition unless already done in callback */
+return checked_server_condition ? OK : auth_check_serv_cond(ablock);
+}
+
+
+/* returns the GSASL status of expanding the Exim string given */
+static int
+condition_check(auth_instance *ablock, uschar *label, uschar *condition_string)
+{
+int exim_rc = auth_check_some_cond(ablock, label, condition_string, FAIL);
+switch (exim_rc)
+  {
+  case OK:	return GSASL_OK;
+  case DEFER:	sasl_error_should_defer = TRUE;
+		return GSASL_AUTHENTICATION_ERROR;
+  case FAIL:	return GSASL_AUTHENTICATION_ERROR;
+  default:	log_write(0, LOG_PANIC_DIE|LOG_CONFIG_FOR, "%s authenticator:  "
+		  "Unhandled return from checking %s: %d",
+		  ablock->name, label, exim_rc);
+  }
+
+/* NOTREACHED */
+return GSASL_AUTHENTICATION_ERROR;
+}
+
+
+static void
+set_exim_authvar_from_prop(Gsasl_session * sctx, Gsasl_property prop)
+{
+uschar * propval = US gsasl_property_fast(sctx, prop);
+int i = expand_nmax, j = i + 1;
+propval = propval ? string_copy(propval) : US"";
+auth_vars[i] = expand_nstring[j] = propval;
+expand_nlength[j] = Ustrlen(propval);
+expand_nmax = j;
+}
+
+static void
+set_exim_authvars_from_a_az_r_props(Gsasl_session * sctx)
+{
+if (expand_nmax > 0 ) return;
+
+/* Asking for GSASL_AUTHZID calls back into us if we use
+gsasl_property_get(), thus the use of gsasl_property_fast().
+Do we really want to hardcode limits per mechanism?  What happens when
+a new mechanism is added to the library.  It *shouldn't* result in us
+needing to add more glue, since avoiding that is a large part of the
+point of SASL. */
+
+set_exim_authvar_from_prop(sctx, GSASL_AUTHID);
+set_exim_authvar_from_prop(sctx, GSASL_AUTHZID);
+set_exim_authvar_from_prop(sctx, GSASL_REALM);
+}
+
+
+static int
+prop_from_option(Gsasl_session * sctx, Gsasl_property prop,
+  const uschar * option)
+{
+HDEBUG(D_auth) debug_printf(" %s\n", gsasl_prop_code_to_name(prop));
+if (option)
+  {
+  set_exim_authvars_from_a_az_r_props(sctx);
+  option = expand_cstring(option);
+  HDEBUG(D_auth) debug_printf("  '%s'\n", option);
+  if (*option)
+    gsasl_property_set(sctx, prop, CCS option);
+  return GSASL_OK;
+  }
+HDEBUG(D_auth) debug_printf("  option not set\n");
+return GSASL_NO_CALLBACK;
+}
+
+static int
+server_callback(Gsasl *ctx, Gsasl_session *sctx, Gsasl_property prop,
+  auth_instance *ablock)
+{
+char *tmps;
+uschar *s, *propval;
+int cbrc = GSASL_NO_CALLBACK;
+auth_gsasl_options_block *ob =
+  (auth_gsasl_options_block *)(ablock->options_block);
+
+HDEBUG(D_auth) debug_printf("GNU SASL callback %s for %s/%s as server\n",
+	    gsasl_prop_code_to_name(prop), ablock->name, ablock->public_name);
+
+for (int i = 0; i < AUTH_VARS; i++) auth_vars[i] = NULL;
+expand_nmax = 0;
+
+switch (prop)
+  {
+  case GSASL_VALIDATE_SIMPLE:
+    /* GSASL_AUTHID, GSASL_AUTHZID, and GSASL_PASSWORD */
+    set_exim_authvar_from_prop(sctx, GSASL_AUTHID);
+    set_exim_authvar_from_prop(sctx, GSASL_AUTHZID);
+    set_exim_authvar_from_prop(sctx, GSASL_PASSWORD);
+
+    cbrc = condition_check(ablock, US"server_condition", ablock->server_condition);
+    checked_server_condition = TRUE;
+    break;
+
+  case GSASL_VALIDATE_EXTERNAL:
+    if (!ablock->server_condition)
+      {
+      HDEBUG(D_auth) debug_printf("No server_condition supplied, to validate EXTERNAL\n");
+      cbrc = GSASL_AUTHENTICATION_ERROR;
+      break;
+      }
+    set_exim_authvar_from_prop(sctx, GSASL_AUTHZID);
+
+    cbrc = condition_check(ablock,
+	US"server_condition (EXTERNAL)", ablock->server_condition);
+    checked_server_condition = TRUE;
+    break;
+
+  case GSASL_VALIDATE_ANONYMOUS:
+    if (!ablock->server_condition)
+      {
+      HDEBUG(D_auth) debug_printf("No server_condition supplied, to validate ANONYMOUS\n");
+      cbrc = GSASL_AUTHENTICATION_ERROR;
+      break;
+      }
+    set_exim_authvar_from_prop(sctx, GSASL_ANONYMOUS_TOKEN);
+
+    cbrc = condition_check(ablock,
+	US"server_condition (ANONYMOUS)", ablock->server_condition);
+    checked_server_condition = TRUE;
+    break;
+
+  case GSASL_VALIDATE_GSSAPI:
+    /* GSASL_AUTHZID and GSASL_GSSAPI_DISPLAY_NAME
+    The display-name is authenticated as part of GSS, the authzid is claimed
+    by the SASL integration after authentication; protected against tampering
+    (if the SASL mechanism supports that, which Kerberos does) but is
+    unverified, same as normal for other mechanisms.
+     First coding, we had these values swapped, but for consistency and prior
+    to the first release of Exim with this authenticator, they've been
+    switched to match the ordering of GSASL_VALIDATE_SIMPLE. */
+
+    set_exim_authvar_from_prop(sctx, GSASL_GSSAPI_DISPLAY_NAME);
+    set_exim_authvar_from_prop(sctx, GSASL_AUTHZID);
+
+    /* In this one case, it perhaps makes sense to default back open?
+    But for consistency, let's just mandate server_condition here too. */
+
+    cbrc = condition_check(ablock,
+	US"server_condition (GSSAPI family)", ablock->server_condition);
+    checked_server_condition = TRUE;
+    break;
+
+  case GSASL_SCRAM_ITER:
+    cbrc = prop_from_option(sctx, prop, ob->server_scram_iter);
+    break;
+
+  case GSASL_SCRAM_SALT:
+    cbrc = prop_from_option(sctx, prop, ob->server_scram_salt);
+    break;
+
+#ifdef EXIM_GSASL_SCRAM_S_KEY
+  case GSASL_SCRAM_STOREDKEY:
+    cbrc = prop_from_option(sctx, prop, ob->server_s_key);
+    break;
+
+  case GSASL_SCRAM_SERVERKEY:
+    cbrc = prop_from_option(sctx, prop, ob->server_key);
+    break;
+#endif
+
+  case GSASL_PASSWORD:
+    /* SCRAM-*: GSASL_AUTHID, GSASL_AUTHZID and GSASL_REALM
+       DIGEST-MD5: GSASL_AUTHID, GSASL_AUTHZID and GSASL_REALM
+       CRAM-MD5: GSASL_AUTHID
+       PLAIN: GSASL_AUTHID and GSASL_AUTHZID
+       LOGIN: GSASL_AUTHID
+     */
+    set_exim_authvars_from_a_az_r_props(sctx);
+
+    if (!(s = ob->server_password))
+      {
+      HDEBUG(D_auth) debug_printf("option not set\n");
+      break;
+      }
+    if (!(tmps = CS expand_string(s)))
+      {
+      sasl_error_should_defer = !f.expand_string_forcedfail;
+      HDEBUG(D_auth) debug_printf("server_password expansion failed, so "
+	  "can't tell GNU SASL library the password for %s\n", auth_vars[0]);
+      return GSASL_AUTHENTICATION_ERROR;
+      }
+    HDEBUG(D_auth) debug_printf("  set\n");
+    gsasl_property_set(sctx, GSASL_PASSWORD, tmps);
+
+    /* This is inadequate; don't think Exim's store stacks are geared
+    for memory wiping, so expanding strings will leave stuff laying around.
+    But no need to compound the problem, so get rid of the one we can. */
+
+    memset(tmps, '\0', strlen(tmps));
+    cbrc = GSASL_OK;
+    break;
+
+  default:
+    HDEBUG(D_auth) debug_printf(" Unrecognised callback: %d\n", prop);
+    cbrc = GSASL_NO_CALLBACK;
+  }
+
+HDEBUG(D_auth) debug_printf("Returning %s (%s)\n",
+    gsasl_strerror_name(cbrc), gsasl_strerror(cbrc));
+
+return cbrc;
+}
+
+
+/******************************************************************************/
+
+#define PROP_OPTIONAL	BIT(0)
+
+static BOOL
+set_client_prop(Gsasl_session * sctx, Gsasl_property prop, uschar * val,
+  unsigned flags, uschar * buffer, int buffsize)
+{
+uschar * s;
+int rc;
+
+if (!val) return !!(flags & PROP_OPTIONAL);
+if (!(s = expand_string(val)) || !(flags & PROP_OPTIONAL) && !*s)
+  {
+  string_format(buffer, buffsize, "%s", expand_string_message);
+  return FALSE;
+  }
+if (*s)
+  {
+  HDEBUG(D_auth) debug_printf("%s: set %s = '%s'\n", __FUNCTION__,
+    gsasl_prop_code_to_name(prop), s);
+  gsasl_property_set(sctx, prop, CS s);
+  }
+
+return TRUE;
+}
+
+/*************************************************
+*              Client entry point                *
+*************************************************/
+
+/* For interface, see auths/README */
+
+int
+auth_gsasl_client(
+  auth_instance *ablock,		/* authenticator block */
+  void * sx,				/* connection */
+  int timeout,				/* command timeout */
+  uschar *buffer,			/* buffer for reading response */
+  int buffsize)				/* size of buffer */
+{
+auth_gsasl_options_block *ob =
+  (auth_gsasl_options_block *)(ablock->options_block);
+Gsasl_session * sctx = NULL;
+struct callback_exim_state cb_state;
+uschar * s;
+BOOL initial = TRUE;
+int rc, yield = FAIL;
+
+HDEBUG(D_auth)
+  debug_printf("GNU SASL: initialising session for %s, mechanism %s\n",
+      ablock->name, ob->server_mech);
+
+*buffer = 0;
+
+#ifndef DISABLE_TLS
+if (tls_out.channelbinding && ob->client_channelbinding)
+  {
+# ifdef EXPERIMENTAL_TLS_RESUME
+  if (!tls_out.ext_master_secret && tls_out.resumption == RESUME_USED)
+    {		/* per RFC 7677 section 4 */
+    string_format(buffer, buffsize, "%s",
+      "channel binding not usable on resumed TLS without extended-master-secret");
+    return FAIL;
+    }
+# endif
+# ifdef CHANNELBIND_HACK
+  /* This is a gross hack to get around the library a) requiring that
+  c-b was already set, at the _start() call, and b) caching a b64'd
+  version of the binding then which it never updates. */
+
+  gsasl_callback_hook_set(gsasl_ctx, tls_out.channelbinding);
+# endif
+  }
+#endif
+
+if ((rc = gsasl_client_start(gsasl_ctx, CCS ob->server_mech, &sctx)) != GSASL_OK)
+  {
+  string_format(buffer, buffsize, "GNU SASL: session start failure: %s (%s)",
+      gsasl_strerror_name(rc), gsasl_strerror(rc));
+  HDEBUG(D_auth) debug_printf("%s\n", buffer);
+  return ERROR;
+  }
+
+cb_state.ablock = ablock;
+cb_state.currently = CURRENTLY_CLIENT;
+gsasl_session_hook_set(sctx, &cb_state);
+
+/* Set properties */
+
+if (  !set_client_prop(sctx, GSASL_SCRAM_SALTED_PASSWORD, ob->client_spassword,
+		  0, buffer, buffsize)
+      &&
+      !set_client_prop(sctx, GSASL_PASSWORD, ob->client_password,
+		  0, buffer, buffsize)
+   || !set_client_prop(sctx, GSASL_AUTHID, ob->client_username,
+		  0, buffer, buffsize)
+   || !set_client_prop(sctx, GSASL_AUTHZID, ob->client_authz,
+		  PROP_OPTIONAL, buffer, buffsize)
+   )
+  return ERROR;
+
+#ifndef DISABLE_TLS
+if (tls_out.channelbinding)
+  if (ob->client_channelbinding)
+    {
+    HDEBUG(D_auth) debug_printf("Auth %s: Enabling channel-binding\n",
+	ablock->name);
+# ifndef CHANNELBIND_HACK
+    gsasl_property_set(sctx, GSASL_CB_TLS_UNIQUE, CCS tls_out.channelbinding);
+# endif
+    }
+  else
+    HDEBUG(D_auth)
+      debug_printf("Auth %s: Not enabling channel-binding (data available)\n",
+	  ablock->name);
+#endif
+
+/* Run the SASL conversation with the server */
+
+for(s = NULL; ;)
+  {
+  uschar * outstr;
+  BOOL fail;
+
+  rc = gsasl_step64(sctx, CS s, CSS &outstr);
+
+  fail = initial
+    ? smtp_write_command(sx, SCMD_FLUSH,
+			outstr ? "AUTH %s %s\r\n" : "AUTH %s\r\n",
+			ablock->public_name, outstr) <= 0
+    : outstr
+    ? smtp_write_command(sx, SCMD_FLUSH, "%s\r\n", outstr) <= 0
+    : FALSE;
+  if (outstr && *outstr) free(outstr);
+  if (fail)
+    {
+    yield = FAIL_SEND;
+    goto done;
+    }
+  initial = FALSE;
+
+  if (rc != GSASL_NEEDS_MORE)
+    {
+    if (rc != GSASL_OK)
+      {
+      string_format(buffer, buffsize, "gsasl: %s", gsasl_strerror(rc));
+      break;
+      }
+
+    /* expecting a final 2xx from the server, accepting the AUTH */
+
+    if (smtp_read_response(sx, buffer, buffsize, '2', timeout))
+      yield = OK;
+    break;	/* from SASL sequence loop */
+    }
+
+  /* 2xx or 3xx response is acceptable.  If 2xx, no further input */
+
+  if (!smtp_read_response(sx, buffer, buffsize, '3', timeout))
+    if (errno == 0 && buffer[0] == '2')
+      buffer[4] = '\0';
+    else
+      {
+      yield = FAIL;
+      goto done;
+      }
+  s = buffer + 4;
+  }
+
+done:
+HDEBUG(D_auth)
+  {
+  const uschar * s = CUS gsasl_property_fast(sctx, GSASL_SCRAM_SALTED_PASSWORD);
+  if (s) debug_printf(" - SaltedPassword: '%s'\n", s);
+  }
+
+gsasl_finish(sctx);
+return yield;
+}
+
+static int
+client_callback(Gsasl *ctx, Gsasl_session *sctx, Gsasl_property prop, auth_instance *ablock)
+{
+HDEBUG(D_auth) debug_printf("GNU SASL callback %s for %s/%s as client\n",
+	    gsasl_prop_code_to_name(prop), ablock->name, ablock->public_name);
+switch (prop)
+  {
+  case GSASL_CB_TLS_UNIQUE:
+    HDEBUG(D_auth)
+      debug_printf(" filling in\n");
+    gsasl_property_set(sctx, GSASL_CB_TLS_UNIQUE, CCS tls_out.channelbinding);
+    break;
+  default:
+    HDEBUG(D_auth)
+      debug_printf(" not providing one\n");
+    break;
+  }
+return GSASL_NO_CALLBACK;
+}
+
+/*************************************************
+*                Diagnostic API                  *
+*************************************************/
+
+void
+auth_gsasl_version_report(FILE *f)
+{
+const char *runtime;
+runtime = gsasl_check_version(NULL);
+fprintf(f, "Library version: GNU SASL: Compile: %s\n"
+	   "                           Runtime: %s\n",
+	GSASL_VERSION, runtime);
+}
+
+
+
+/* Dummy */
+void auth_gsasl_macros(void) {}
+
+#endif   /*!MACRO_PREDEF*/
+#endif  /* AUTH_GSASL */
+
+/* End of gsasl_exim.c */
diff --git a/src/auths/gsasl_exim.h b/src/auths/gsasl_exim.h
new file mode 100644
index 0000000..028259a
--- /dev/null
+++ b/src/auths/gsasl_exim.h
@@ -0,0 +1,53 @@
+/*************************************************
+*     Exim - an Internet mail transport agent    *
+*************************************************/
+
+/* Copyright (c) University of Cambridge 1995 - 2012 */
+/* Copyright (c) The Exim Maintainers 2019-2020 */
+/* See the file NOTICE for conditions of use and distribution. */
+
+/* Copyright (c) Twitter Inc 2012 */
+
+/* Interface to GNU SASL library for generic authentication. */
+
+/* Authenticator-specific options. */
+
+typedef struct {
+  uschar *server_service;
+  uschar *server_hostname;
+  uschar *server_realm;
+  uschar *server_mech;
+  uschar *server_password;
+  uschar *server_key;
+  uschar *server_s_key;
+  uschar *server_scram_iter;
+  uschar *server_scram_salt;
+
+  uschar *client_username;
+  uschar *client_password;
+  uschar *client_authz;
+  uschar *client_spassword;
+
+  BOOL    server_channelbinding;
+  BOOL	  client_channelbinding;
+} auth_gsasl_options_block;
+
+/* Data for reading the authenticator-specific options. */
+
+extern optionlist auth_gsasl_options[];
+extern int auth_gsasl_options_count;
+
+/* Defaults for the authenticator-specific options. */
+
+extern auth_gsasl_options_block auth_gsasl_option_defaults;
+
+/* The entry points for the mechanism */
+
+extern void auth_gsasl_init(auth_instance *);
+extern int auth_gsasl_server(auth_instance *, uschar *);
+extern int auth_gsasl_client(auth_instance *, void *,
+				int, uschar *, int);
+extern void auth_gsasl_version_report(FILE *f);
+extern void auth_gsasl_macros(void);
+
+/* End of gsasl_exim.h */
diff --git a/src/auths/heimdal_gssapi.c b/src/auths/heimdal_gssapi.c
new file mode 100644
index 0000000..a09d454
--- /dev/null
+++ b/src/auths/heimdal_gssapi.c
@@ -0,0 +1,617 @@
+/*************************************************
+*     Exim - an Internet mail transport agent    *
+*************************************************/
+
+/* Copyright (c) University of Cambridge 1995 - 2018 */
+/* Copyright (c) The Exim Maintainers 2020 */
+/* See the file NOTICE for conditions of use and distribution. */
+
+/* Copyright (c) Twitter Inc 2012
+   Author: Phil Pennock <pdp@exim.org> */
+/* Copyright (c) Phil Pennock 2012 */
+
+/* Interface to Heimdal library for GSSAPI authentication. */
+
+/* Naming and rationale
+
+Sensibly, this integration would be deferred to a SASL library, but none
+of them appear to offer keytab file selection interfaces in their APIs.  It
+might be that this driver only requires minor modification to work with MIT
+Kerberos.
+
+Heimdal provides a number of interfaces for various forms of authentication.
+As GS2 does not appear to provide keytab control interfaces either, we may
+end up supporting that too.  It's possible that we could trivially expand to
+support NTLM support via Heimdal, etc.  Rather than try to be too generic
+immediately, this driver is directly only supporting GSSAPI.
+
+Without rename, we could add an option for GS2 support in the future.
+*/
+
+/* Sources
+
+* mailcheck-imap (Perl, client-side, written by me years ago)
+* gsasl driver (GPL, server-side)
+* heimdal sources and man-pages, plus http://www.h5l.org/manual/
+* FreeBSD man-pages (very informative!)
+* http://www.ggf.org/documents/GFD.24.pdf confirming GSS_KRB5_REGISTER_ACCEPTOR_IDENTITY_X
+  semantics, that found by browsing Heimdal source to find how to set the keytab; however,
+  after multiple attempts I failed to get that to work and instead switched to
+  gsskrb5_register_acceptor_identity().
+*/
+
+#include "../exim.h"
+
+#ifndef AUTH_HEIMDAL_GSSAPI
+/* dummy function to satisfy compilers when we link in an "empty" file. */
+static void dummy(int x);
+static void dummy2(int x) { dummy(x-1); }
+static void dummy(int x) { dummy2(x-1); }
+#else
+
+#include <gssapi/gssapi.h>
+#include <gssapi/gssapi_krb5.h>
+
+/* for the _init debugging */
+#include <krb5.h>
+
+#include "heimdal_gssapi.h"
+
+/* Authenticator-specific options. */
+optionlist auth_heimdal_gssapi_options[] = {
+  { "server_hostname",      opt_stringptr,
+      OPT_OFF(auth_heimdal_gssapi_options_block, server_hostname) },
+  { "server_keytab",        opt_stringptr,
+      OPT_OFF(auth_heimdal_gssapi_options_block, server_keytab) },
+  { "server_service",       opt_stringptr,
+      OPT_OFF(auth_heimdal_gssapi_options_block, server_service) }
+};
+
+int auth_heimdal_gssapi_options_count =
+  sizeof(auth_heimdal_gssapi_options)/sizeof(optionlist);
+
+/* Defaults for the authenticator-specific options. */
+auth_heimdal_gssapi_options_block auth_heimdal_gssapi_option_defaults = {
+  US"$primary_hostname",    /* server_hostname */
+  NULL,                     /* server_keytab */
+  US"smtp",                 /* server_service */
+};
+
+
+#ifdef MACRO_PREDEF
+
+/* Dummy values */
+void auth_heimdal_gssapi_init(auth_instance *ablock) {}
+int auth_heimdal_gssapi_server(auth_instance *ablock, uschar *data) {return 0;}
+int auth_heimdal_gssapi_client(auth_instance *ablock, void * sx,
+  int timeout, uschar *buffer, int buffsize) {return 0;}
+void auth_heimdal_gssapi_version_report(FILE *f) {}
+
+#else   /*!MACRO_PREDEF*/
+
+
+
+/* "Globals" for managing the heimdal_gssapi interface. */
+
+/* Utility functions */
+static void
+  exim_heimdal_error_debug(const char *, krb5_context, krb5_error_code);
+static int
+  exim_gssapi_error_defer(rmark, OM_uint32, OM_uint32, const char *, ...)
+    PRINTF_FUNCTION(4, 5);
+
+#define EmptyBuf(buf) do { buf.value = NULL; buf.length = 0; } while (0)
+
+
+/*************************************************
+*          Initialization entry point            *
+*************************************************/
+
+/* Called for each instance, after its options have been read, to
+enable consistency checks to be done, or anything else that needs
+to be set up. */
+
+/* Heimdal provides a GSSAPI extension method for setting the keytab;
+in the init, we mostly just use raw krb5 methods so that we can report
+the keytab contents, for -D+auth debugging. */
+
+void
+auth_heimdal_gssapi_init(auth_instance *ablock)
+{
+krb5_context context;
+krb5_keytab keytab;
+krb5_kt_cursor cursor;
+krb5_keytab_entry entry;
+krb5_error_code krc;
+char *principal, *enctype_s;
+const char *k_keytab_typed_name = NULL;
+auth_heimdal_gssapi_options_block *ob =
+  (auth_heimdal_gssapi_options_block *)(ablock->options_block);
+
+ablock->server = FALSE;
+ablock->client = FALSE;
+
+if (!ob->server_service || !*ob->server_service)
+  {
+  HDEBUG(D_auth) debug_printf("heimdal: missing server_service\n");
+  return;
+  }
+
+if ((krc = krb5_init_context(&context)))
+  {
+  int kerr = errno;
+  HDEBUG(D_auth) debug_printf("heimdal: failed to initialise krb5 context: %s\n",
+      strerror(kerr));
+  return;
+  }
+
+if (ob->server_keytab)
+  {
+  k_keytab_typed_name = CCS string_sprintf("file:%s", expand_string(ob->server_keytab));
+  HDEBUG(D_auth) debug_printf("heimdal: using keytab %s\n", k_keytab_typed_name);
+  if ((krc = krb5_kt_resolve(context, k_keytab_typed_name, &keytab)))
+    {
+    HDEBUG(D_auth) exim_heimdal_error_debug("krb5_kt_resolve", context, krc);
+    return;
+    }
+  }
+else
+ {
+  HDEBUG(D_auth) debug_printf("heimdal: using system default keytab\n");
+  if ((krc = krb5_kt_default(context, &keytab)))
+    {
+    HDEBUG(D_auth) exim_heimdal_error_debug("krb5_kt_default", context, krc);
+    return;
+    }
+  }
+
+HDEBUG(D_auth)
+  {
+  /* http://www.h5l.org/manual/HEAD/krb5/krb5_keytab_intro.html */
+  if ((krc = krb5_kt_start_seq_get(context, keytab, &cursor)))
+    exim_heimdal_error_debug("krb5_kt_start_seq_get", context, krc);
+  else
+    {
+    while (!(krc = krb5_kt_next_entry(context, keytab, &entry, &cursor)))
+      {
+      principal = enctype_s = NULL;
+      krb5_unparse_name(context, entry.principal, &principal);
+      krb5_enctype_to_string(context, entry.keyblock.keytype, &enctype_s);
+      debug_printf("heimdal: keytab principal: %s  vno=%d  type=%s\n",
+	  principal ? principal : "??",
+	  entry.vno,
+	  enctype_s ? enctype_s : "??");
+      free(principal);
+      free(enctype_s);
+      krb5_kt_free_entry(context, &entry);
+      }
+    if ((krc = krb5_kt_end_seq_get(context, keytab, &cursor)))
+      exim_heimdal_error_debug("krb5_kt_end_seq_get", context, krc);
+    }
+  }
+
+if ((krc = krb5_kt_close(context, keytab)))
+  HDEBUG(D_auth) exim_heimdal_error_debug("krb5_kt_close", context, krc);
+
+krb5_free_context(context);
+
+ablock->server = TRUE;
+}
+
+
+static void
+exim_heimdal_error_debug(const char *label,
+    krb5_context context, krb5_error_code err)
+{
+const char *kerrsc;
+kerrsc = krb5_get_error_message(context, err);
+debug_printf("heimdal %s: %s\n", label, kerrsc ? kerrsc : "unknown error");
+krb5_free_error_message(context, kerrsc);
+}
+
+/*************************************************
+*             Server entry point                 *
+*************************************************/
+
+/* For interface, see auths/README */
+
+/* GSSAPI notes:
+OM_uint32: portable type for unsigned int32
+gss_buffer_desc / *gss_buffer_t: hold/point-to size_t .length & void *value
+  -- all strings/etc passed in should go through one of these
+  -- when allocated by gssapi, release with gss_release_buffer()
+*/
+
+int
+auth_heimdal_gssapi_server(auth_instance *ablock, uschar *initial_data)
+{
+gss_name_t gclient = GSS_C_NO_NAME;
+gss_name_t gserver = GSS_C_NO_NAME;
+gss_cred_id_t gcred = GSS_C_NO_CREDENTIAL;
+gss_ctx_id_t gcontext = GSS_C_NO_CONTEXT;
+uschar *ex_server_str;
+gss_buffer_desc gbufdesc = GSS_C_EMPTY_BUFFER;
+gss_buffer_desc gbufdesc_in = GSS_C_EMPTY_BUFFER;
+gss_buffer_desc gbufdesc_out = GSS_C_EMPTY_BUFFER;
+gss_OID mech_type;
+OM_uint32 maj_stat, min_stat;
+int step, error_out;
+uschar *tmp1, *tmp2, *from_client;
+auth_heimdal_gssapi_options_block *ob =
+  (auth_heimdal_gssapi_options_block *)(ablock->options_block);
+BOOL handled_empty_ir;
+rmark store_reset_point;
+uschar *keytab;
+uschar sasl_config[4];
+uschar requested_qop;
+
+store_reset_point = store_mark();
+
+HDEBUG(D_auth)
+  debug_printf("heimdal: initialising auth context for %s\n", ablock->name);
+
+/* Construct our gss_name_t gserver describing ourselves */
+tmp1 = expand_string(ob->server_service);
+tmp2 = expand_string(ob->server_hostname);
+ex_server_str = string_sprintf("%s@%s", tmp1, tmp2);
+gbufdesc.value = (void *) ex_server_str;
+gbufdesc.length = Ustrlen(ex_server_str);
+maj_stat = gss_import_name(&min_stat,
+    &gbufdesc, GSS_C_NT_HOSTBASED_SERVICE, &gserver);
+if (GSS_ERROR(maj_stat))
+  return exim_gssapi_error_defer(store_reset_point, maj_stat, min_stat,
+      "gss_import_name(%s)", CS gbufdesc.value);
+
+/* Use a specific keytab, if specified */
+if (ob->server_keytab) 
+  {
+  keytab = expand_string(ob->server_keytab);
+  maj_stat = gsskrb5_register_acceptor_identity(CCS keytab);
+  if (GSS_ERROR(maj_stat))
+    return exim_gssapi_error_defer(store_reset_point, maj_stat, min_stat,
+	"registering keytab \"%s\"", keytab);
+  HDEBUG(D_auth)
+    debug_printf("heimdal: using keytab \"%s\"\n", keytab);
+  }
+
+/* Acquire our credentials */
+maj_stat = gss_acquire_cred(&min_stat,
+    gserver,             /* desired name */
+    0,                   /* time */
+    GSS_C_NULL_OID_SET,  /* desired mechs */
+    GSS_C_ACCEPT,        /* cred usage */
+    &gcred,              /* handle */
+    NULL                 /* actual mechs */,
+    NULL                 /* time rec */);
+if (GSS_ERROR(maj_stat))
+  return exim_gssapi_error_defer(store_reset_point, maj_stat, min_stat,
+      "gss_acquire_cred(%s)", ex_server_str);
+
+maj_stat = gss_release_name(&min_stat, &gserver);
+
+HDEBUG(D_auth) debug_printf("heimdal: have server credentials.\n");
+
+/* Loop talking to client */
+step = 0;
+from_client = initial_data;
+handled_empty_ir = FALSE;
+error_out = OK;
+
+/* buffer sizes: auth_get_data() uses big_buffer, which we grow per
+GSSAPI RFC in _init, if needed, to meet the SHOULD size of 64KB.
+(big_buffer starts life at the MUST size of 16KB). */
+
+/* step values
+0: getting initial data from client to feed into GSSAPI
+1: iterating for as long as GSS_S_CONTINUE_NEEDED
+2: GSS_S_COMPLETE, SASL wrapping for authz and qop to send to client
+3: unpick final auth message from client
+4: break/finish (non-step)
+*/
+while (step < 4)
+  switch (step)
+    {
+    case 0:
+      if (!from_client || !*from_client)
+        {
+	if (handled_empty_ir)
+	  {
+	  HDEBUG(D_auth) debug_printf("gssapi: repeated empty input, grr.\n");
+	  error_out = BAD64;
+	  goto ERROR_OUT;
+	  }
+
+	HDEBUG(D_auth) debug_printf("gssapi: missing initial response, nudging.\n");
+	if ((error_out = auth_get_data(&from_client, US"", 0)) != OK)
+	  goto ERROR_OUT;
+	handled_empty_ir = TRUE;
+	continue;
+	}
+      /* We should now have the opening data from the client, base64-encoded. */
+      step += 1;
+      HDEBUG(D_auth) debug_printf("heimdal: have initial client data\n");
+      break;
+
+    case 1:
+      gbufdesc_in.length = b64decode(from_client, USS &gbufdesc_in.value);
+      if (gclient)
+        {
+	maj_stat = gss_release_name(&min_stat, &gclient);
+	gclient = GSS_C_NO_NAME;
+	}
+      maj_stat = gss_accept_sec_context(&min_stat,
+	  &gcontext,          /* context handle */
+	  gcred,              /* acceptor cred handle */
+	  &gbufdesc_in,       /* input from client */
+	  GSS_C_NO_CHANNEL_BINDINGS,  /* XXX fixme: use the channel bindings from GnuTLS */
+	  &gclient,           /* client identifier */
+	  &mech_type,         /* mechanism in use */
+	  &gbufdesc_out,      /* output to send to client */
+	  NULL,               /* return flags */
+	  NULL,               /* time rec */
+	  NULL                /* delegated cred_handle */
+	  );
+      if (GSS_ERROR(maj_stat))
+        {
+	exim_gssapi_error_defer(NULL, maj_stat, min_stat,
+	    "gss_accept_sec_context()");
+	error_out = FAIL;
+	goto ERROR_OUT;
+	}
+      if (gbufdesc_out.length != 0)
+        {
+	error_out = auth_get_data(&from_client,
+	    gbufdesc_out.value, gbufdesc_out.length);
+	if (error_out != OK)
+	  goto ERROR_OUT;
+
+	gss_release_buffer(&min_stat, &gbufdesc_out);
+	EmptyBuf(gbufdesc_out);
+	}
+      if (maj_stat == GSS_S_COMPLETE)
+        {
+	step += 1;
+	HDEBUG(D_auth) debug_printf("heimdal: GSS complete\n");
+	}
+      else
+	HDEBUG(D_auth) debug_printf("heimdal: need more data\n");
+      break;
+
+    case 2:
+      memset(sasl_config, 0xFF, 4);
+      /* draft-ietf-sasl-gssapi-06.txt defines bitmasks for first octet
+      0x01 No security layer
+      0x02 Integrity protection
+      0x04 Confidentiality protection
+
+      The remaining three octets are the maximum buffer size for wrapped
+      content. */
+      sasl_config[0] = 0x01;  /* Exim does not wrap/unwrap SASL layers after auth */
+      gbufdesc.value = (void *) sasl_config;
+      gbufdesc.length = 4;
+      maj_stat = gss_wrap(&min_stat,
+	  gcontext,
+	  0,                    /* conf_req_flag: integrity only */
+	  GSS_C_QOP_DEFAULT,    /* qop requested */
+	  &gbufdesc,            /* message to protect */
+	  NULL,                 /* conf_state: no confidentiality applied */
+	  &gbufdesc_out         /* output buffer */
+	  );
+      if (GSS_ERROR(maj_stat))
+        {
+	exim_gssapi_error_defer(NULL, maj_stat, min_stat,
+	    "gss_wrap(SASL state after auth)");
+	error_out = FAIL;
+	goto ERROR_OUT;
+	}
+
+      HDEBUG(D_auth) debug_printf("heimdal SASL: requesting QOP with no security layers\n");
+
+      error_out = auth_get_data(&from_client,
+	  gbufdesc_out.value, gbufdesc_out.length);
+      if (error_out != OK)
+	goto ERROR_OUT;
+
+      gss_release_buffer(&min_stat, &gbufdesc_out);
+      EmptyBuf(gbufdesc_out);
+      step += 1;
+      break;
+
+    case 3:
+      gbufdesc_in.length = b64decode(from_client, USS &gbufdesc_in.value);
+      maj_stat = gss_unwrap(&min_stat,
+	  gcontext,
+	  &gbufdesc_in,       /* data from client */
+	  &gbufdesc_out,      /* results */
+	  NULL,               /* conf state */
+	  NULL                /* qop state */
+	  );
+      if (GSS_ERROR(maj_stat))
+        {
+	exim_gssapi_error_defer(NULL, maj_stat, min_stat,
+	    "gss_unwrap(final SASL message from client)");
+	error_out = FAIL;
+	goto ERROR_OUT;
+	}
+      if (gbufdesc_out.length < 4)
+        {
+	HDEBUG(D_auth)
+	  debug_printf("gssapi: final message too short; "
+	      "need flags, buf sizes and optional authzid\n");
+	error_out = FAIL;
+	goto ERROR_OUT;
+	}
+
+      requested_qop = (CS gbufdesc_out.value)[0];
+      if (!(requested_qop & 0x01))
+        {
+	HDEBUG(D_auth)
+	  debug_printf("gssapi: client requested security layers (%x)\n",
+	      (unsigned int) requested_qop);
+	error_out = FAIL;
+	goto ERROR_OUT;
+	}
+
+      for (int i = 0; i < AUTH_VARS; i++) auth_vars[i] = NULL;
+      expand_nmax = 0;
+
+      /* Identifiers:
+      The SASL provided identifier is an unverified authzid.
+      GSSAPI provides us with a verified identifier, but it might be empty
+      for some clients.
+      */
+
+      /* $auth2 is authzid requested at SASL layer */
+      if (gbufdesc_out.length > 4)
+        {
+	expand_nlength[2] = gbufdesc_out.length - 4;
+	auth_vars[1] = expand_nstring[2] =
+	  string_copyn((US gbufdesc_out.value) + 4, expand_nlength[2]);
+	expand_nmax = 2;
+	}
+
+      gss_release_buffer(&min_stat, &gbufdesc_out);
+      EmptyBuf(gbufdesc_out);
+
+      /* $auth1 is GSSAPI display name */
+      maj_stat = gss_display_name(&min_stat,
+	  gclient, &gbufdesc_out, &mech_type);
+      if (GSS_ERROR(maj_stat))
+        {
+	auth_vars[1] = expand_nstring[2] = NULL;
+	expand_nmax = 0;
+	exim_gssapi_error_defer(NULL, maj_stat, min_stat,
+	    "gss_display_name(client identifier)");
+	error_out = FAIL;
+	goto ERROR_OUT;
+	}
+
+      expand_nlength[1] = gbufdesc_out.length;
+      auth_vars[0] = expand_nstring[1] =
+	string_copyn(gbufdesc_out.value, gbufdesc_out.length);
+
+      if (expand_nmax == 0)	/* should be: authzid was empty */
+	{
+	expand_nmax = 2;
+	expand_nlength[2] = expand_nlength[1];
+	auth_vars[1] = expand_nstring[2] = string_copyn(expand_nstring[1], expand_nlength[1]);
+	HDEBUG(D_auth)
+	  debug_printf("heimdal SASL: empty authzid, set to dup of GSSAPI display name\n");
+	}
+
+      HDEBUG(D_auth)
+	debug_printf("heimdal SASL: happy with client request\n"
+	   "  auth1 (verified GSSAPI display-name): \"%s\"\n"
+	   "  auth2 (unverified SASL requested authzid): \"%s\"\n",
+	   auth_vars[0], auth_vars[1]);
+
+      step += 1;
+      break;
+
+    } /* switch */
+  /* while step */
+
+
+ERROR_OUT:
+maj_stat = gss_release_cred(&min_stat, &gcred);
+if (gclient)
+  {
+  gss_release_name(&min_stat, &gclient);
+  gclient = GSS_C_NO_NAME;
+  }
+if (gbufdesc_out.length)
+  {
+  gss_release_buffer(&min_stat, &gbufdesc_out);
+  EmptyBuf(gbufdesc_out);
+  }
+if (gcontext != GSS_C_NO_CONTEXT)
+  gss_delete_sec_context(&min_stat, &gcontext, GSS_C_NO_BUFFER);
+
+store_reset(store_reset_point);
+
+if (error_out != OK)
+  return error_out;
+
+/* Auth succeeded, check server_condition */
+return auth_check_serv_cond(ablock);
+}
+
+
+static int
+exim_gssapi_error_defer(rmark store_reset_point,
+    OM_uint32 major, OM_uint32 minor,
+    const char *format, ...)
+{
+va_list ap;
+OM_uint32 maj_stat, min_stat;
+OM_uint32 msgcontext = 0;
+gss_buffer_desc status_string;
+gstring * g;
+
+HDEBUG(D_auth)
+  {
+  va_start(ap, format);
+  g = string_vformat(NULL, SVFMT_EXTEND|SVFMT_REBUFFER, format, ap);
+  va_end(ap);
+  }
+
+auth_defer_msg = NULL;
+
+do {
+  maj_stat = gss_display_status(&min_stat,
+      major, GSS_C_GSS_CODE, GSS_C_NO_OID, &msgcontext, &status_string);
+
+  if (!auth_defer_msg)
+    auth_defer_msg = string_copy(US status_string.value);
+
+  HDEBUG(D_auth) debug_printf("heimdal %s: %.*s\n",
+      string_from_gstring(g), (int)status_string.length,
+      CS status_string.value);
+  gss_release_buffer(&min_stat, &status_string);
+
+  } while (msgcontext != 0);
+
+if (store_reset_point)
+  store_reset(store_reset_point);
+return DEFER;
+}
+
+
+/*************************************************
+*              Client entry point                *
+*************************************************/
+
+/* For interface, see auths/README */
+
+int
+auth_heimdal_gssapi_client(
+  auth_instance *ablock,                 /* authenticator block */
+  void * sx,				 /* connection */
+  int timeout,                           /* command timeout */
+  uschar *buffer,                        /* buffer for reading response */
+  int buffsize)                          /* size of buffer */
+{
+HDEBUG(D_auth)
+  debug_printf("Client side NOT IMPLEMENTED: you should not see this!\n");
+/* NOT IMPLEMENTED */
+return FAIL;
+}
+
+/*************************************************
+*                Diagnostic API                  *
+*************************************************/
+
+void
+auth_heimdal_gssapi_version_report(FILE *f)
+{
+/* No build-time constants available unless we link against libraries at
+build-time and export the result as a string into a header ourselves. */
+fprintf(f, "Library version: Heimdal: Runtime: %s\n"
+	   " Build Info: %s\n",
+	heimdal_version, heimdal_long_version);
+}
+
+#endif   /*!MACRO_PREDEF*/
+#endif  /* AUTH_HEIMDAL_GSSAPI */
+
+/* End of heimdal_gssapi.c */
diff --git a/src/auths/heimdal_gssapi.h b/src/auths/heimdal_gssapi.h
new file mode 100644
index 0000000..b682b5f
--- /dev/null
+++ b/src/auths/heimdal_gssapi.h
@@ -0,0 +1,38 @@
+/*************************************************
+*     Exim - an Internet mail transport agent    *
+*************************************************/
+
+/* Copyright (c) University of Cambridge 1995 - 2012 */
+/* See the file NOTICE for conditions of use and distribution. */
+
+/* Copyright (c) Twitter Inc 2012
+   Author: Phil Pennock <pdp@exim.org> */
+/* Copyright (c) Phil Pennock 2012 */
+
+/* Interface to Heimdal library for GSSAPI authentication. */
+
+/* Authenticator-specific options. */
+
+typedef struct {
+  uschar *server_hostname;
+  uschar *server_keytab;
+  uschar *server_service;
+} auth_heimdal_gssapi_options_block;
+
+/* Data for reading the authenticator-specific options. */
+
+extern optionlist auth_heimdal_gssapi_options[];
+extern int auth_heimdal_gssapi_options_count;
+
+/* Defaults for the authenticator-specific options. */
+
+extern auth_heimdal_gssapi_options_block auth_heimdal_gssapi_option_defaults;
+
+/* The entry points for the mechanism */
+
+extern void auth_heimdal_gssapi_init(auth_instance *);
+extern int auth_heimdal_gssapi_server(auth_instance *, uschar *);
+extern int auth_heimdal_gssapi_client(auth_instance *, void *, int, uschar *, int);
+extern void auth_heimdal_gssapi_version_report(FILE *f);
+
+/* End of heimdal_gssapi.h */
diff --git a/src/auths/plaintext.c b/src/auths/plaintext.c
new file mode 100644
index 0000000..778e6c2
--- /dev/null
+++ b/src/auths/plaintext.c
@@ -0,0 +1,179 @@
+/*************************************************
+*     Exim - an Internet mail transport agent    *
+*************************************************/
+
+/* Copyright (c) University of Cambridge 1995 - 2018 */
+/* Copyright (c) The Exim Maintainers 2020 */
+/* See the file NOTICE for conditions of use and distribution. */
+
+#include "../exim.h"
+#include "plaintext.h"
+
+
+/* Options specific to the plaintext authentication mechanism. */
+
+optionlist auth_plaintext_options[] = {
+  { "client_ignore_invalid_base64", opt_bool,
+      OPT_OFF(auth_plaintext_options_block, client_ignore_invalid_base64) },
+  { "client_send",        opt_stringptr,
+      OPT_OFF(auth_plaintext_options_block, client_send) },
+  { "server_prompts",     opt_stringptr,
+      OPT_OFF(auth_plaintext_options_block, server_prompts) }
+};
+
+/* Size of the options list. An extern variable has to be used so that its
+address can appear in the tables drtables.c. */
+
+int auth_plaintext_options_count =
+  sizeof(auth_plaintext_options)/sizeof(optionlist);
+
+/* Default private options block for the plaintext authentication method. */
+
+auth_plaintext_options_block auth_plaintext_option_defaults = {
+  NULL,              /* server_prompts */
+  NULL,              /* client_send */
+  FALSE              /* client_ignore_invalid_base64 */
+};
+
+
+#ifdef MACRO_PREDEF
+
+/* Dummy values */
+void auth_plaintext_init(auth_instance *ablock) {}
+int auth_plaintext_server(auth_instance *ablock, uschar *data) {return 0;}
+int auth_plaintext_client(auth_instance *ablock, void * sx, int timeout,
+    uschar *buffer, int buffsize) {return 0;}
+
+#else   /*!MACRO_PREDEF*/
+
+
+
+/*************************************************
+*          Initialization entry point            *
+*************************************************/
+
+/* Called for each instance, after its options have been read, to
+enable consistency checks to be done, or anything else that needs
+to be set up. */
+
+void
+auth_plaintext_init(auth_instance *ablock)
+{
+auth_plaintext_options_block *ob =
+  (auth_plaintext_options_block *)(ablock->options_block);
+if (ablock->public_name == NULL) ablock->public_name = ablock->name;
+if (ablock->server_condition != NULL) ablock->server = TRUE;
+if (ob->client_send != NULL) ablock->client = TRUE;
+}
+
+
+
+/*************************************************
+*             Server entry point                 *
+*************************************************/
+
+/* For interface, see auths/README */
+
+int
+auth_plaintext_server(auth_instance * ablock, uschar * data)
+{
+auth_plaintext_options_block * ob =
+  (auth_plaintext_options_block *)(ablock->options_block);
+const uschar * prompts = ob->server_prompts;
+uschar * s;
+int number = 1;
+int rc;
+int sep = 0;
+
+/* Expand a non-empty list of prompt strings */
+
+if (prompts)
+  if (!(prompts = expand_cstring(prompts)))
+    {
+    auth_defer_msg = expand_string_message;
+    return DEFER;
+    }
+
+/* If data was supplied on the AUTH command, decode it, and split it up into
+multiple items at binary zeros. The strings are put into $auth1, $auth2, etc,
+up to a maximum. To retain backwards compatibility, they are also put int $1,
+$2, etc. If the data consists of the string "=" it indicates a single, empty
+string. */
+
+if (*data)
+  if ((rc = auth_read_input(data)) != OK)
+    return rc;
+
+/* Now go through the list of prompt strings. Skip over any whose data has
+already been provided as part of the AUTH command. For the rest, send them
+out as prompts, and get a data item back. If the data item is "*", abandon the
+authentication attempt. Otherwise, split it into items as above. */
+
+while (  (s = string_nextinlist(&prompts, &sep, big_buffer, big_buffer_size))
+      && expand_nmax < EXPAND_MAXN)
+  if (number++ > expand_nmax)
+    if ((rc = auth_prompt(CUS s)) != OK)
+      return rc;
+
+/* We now have a number of items of data in $auth1, $auth2, etc (and also, for
+compatibility, in $1, $2, etc). Authentication and authorization are handled
+together for this authenticator by expanding the server_condition option. Note
+that ablock->server_condition is always non-NULL because that's what configures
+this authenticator as a server. */
+
+return auth_check_serv_cond(ablock);
+}
+
+
+
+/*************************************************
+*              Client entry point                *
+*************************************************/
+
+/* For interface, see auths/README */
+
+int
+auth_plaintext_client(
+  auth_instance *ablock,                 /* authenticator block */
+  void * sx,				 /* smtp connextion */
+  int timeout,                           /* command timeout */
+  uschar *buffer,                        /* buffer for reading response */
+  int buffsize)                          /* size of buffer */
+{
+auth_plaintext_options_block *ob =
+  (auth_plaintext_options_block *)(ablock->options_block);
+const uschar * text = ob->client_send;
+const uschar * s;
+int sep = 0;
+int auth_var_idx = 0, rc;
+int flags = AUTH_ITEM_FIRST;
+
+if (ob->client_ignore_invalid_base64)
+  flags |= AUTH_ITEM_IGN64;
+
+/* The text is broken up into a number of different data items, which are
+sent one by one. The first one is sent with the AUTH command; the remainder are
+sent in response to subsequent prompts. Each is expanded before being sent. */
+
+while ((s = string_nextinlist(&text, &sep, NULL, 0)))
+  {
+  if (!text)
+    flags |= AUTH_ITEM_LAST;
+
+  if ((rc = auth_client_item(sx, ablock, &s, flags, timeout, buffer, buffsize))
+       != DEFER)
+    return rc;
+
+  flags &= ~AUTH_ITEM_FIRST;
+
+  if (auth_var_idx < AUTH_VARS)
+    auth_vars[auth_var_idx++] = string_copy(s);
+  }
+
+/* Control should never actually get here. */
+
+return FAIL;
+}
+
+#endif   /*!MACRO_PREDEF*/
+/* End of plaintext.c */
diff --git a/src/auths/plaintext.h b/src/auths/plaintext.h
new file mode 100644
index 0000000..4c6d011
--- /dev/null
+++ b/src/auths/plaintext.h
@@ -0,0 +1,31 @@
+/*************************************************
+*     Exim - an Internet mail transport agent    *
+*************************************************/
+
+/* Copyright (c) University of Cambridge 1995 - 2009 */
+/* See the file NOTICE for conditions of use and distribution. */
+
+/* Private structure for the private options. */
+
+typedef struct {
+  uschar *server_prompts;
+  uschar *client_send;
+  BOOL    client_ignore_invalid_base64;
+} auth_plaintext_options_block;
+
+/* Data for reading the private options. */
+
+extern optionlist auth_plaintext_options[];
+extern int auth_plaintext_options_count;
+
+/* Block containing default values. */
+
+extern auth_plaintext_options_block auth_plaintext_option_defaults;
+
+/* The entry points for the mechanism */
+
+extern void auth_plaintext_init(auth_instance *);
+extern int auth_plaintext_server(auth_instance *, uschar *);
+extern int auth_plaintext_client(auth_instance *, void *, int, uschar *, int);
+
+/* End of plaintext.h */
diff --git a/src/auths/pwcheck.c b/src/auths/pwcheck.c
new file mode 100644
index 0000000..f733b98
--- /dev/null
+++ b/src/auths/pwcheck.c
@@ -0,0 +1,454 @@
+/* SASL server API implementation
+ * Rob Siemborski
+ * Tim Martin
+ * $Id: checkpw.c,v 1.49 2002/03/07 19:14:04 ken3 Exp $
+ */
+/*
+ * Copyright (c) 2001 Carnegie Mellon University.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * 3. The name "Carnegie Mellon University" must not be used to
+ *    endorse or promote products derived from this software without
+ *    prior written permission. For permission or any other legal
+ *    details, please contact
+ *      Office of Technology Transfer
+ *      Carnegie Mellon University
+ *      5000 Forbes Avenue
+ *      Pittsburgh, PA  15213-3890
+ *      (412) 268-4387, fax: (412) 268-7395
+ *      tech-transfer@andrew.cmu.edu
+ *
+ * 4. Redistributions of any form whatsoever must retain the following
+ *    acknowledgment:
+ *    "This product includes software developed by Computing Services
+ *     at Carnegie Mellon University (http://www.cmu.edu/computing/)."
+ *
+ * CARNEGIE MELLON UNIVERSITY DISCLAIMS ALL WARRANTIES WITH REGARD TO
+ * THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+ * AND FITNESS, IN NO EVENT SHALL CARNEGIE MELLON UNIVERSITY BE LIABLE
+ * FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
+ * AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
+ * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/*
+ * Taken from Cyrus-SASL library and adapted by Alexander S. Sabourenkov
+ * Oct 2001 - Apr 2002: Slightly modified by Philip Hazel.
+ * Aug 2003: new code for saslauthd from Alexander S. Sabourenkov incorporated
+ *           by Philip Hazel (minor mods to avoid compiler warnings)
+ * Oct 2006: (PH) removed redundant tests on "reply" being NULL - some were
+ *           missing, and confused someone who was using this code for some
+ *           other purpose. Here in Exim, "reply" is never NULL.
+ *
+ * screwdriver@lxnt.info
+ *
+ */
+
+/* Originally this module supported only the pwcheck daemon, which is where its
+name comes from. Nowadays it supports saslauthd as well; pwcheck is in fact
+deprecated. The definitions of CYRUS_PWCHECK_SOCKET and CYRUS_SASLAUTHD_SOCKET
+determine whether the facilities are actually supported or not. */
+
+
+#include "../exim.h"
+#include "pwcheck.h"
+
+
+#if defined(CYRUS_PWCHECK_SOCKET) || defined(CYRUS_SASLAUTHD_SOCKET)
+
+#include <sys/uio.h>
+
+static int retry_read(int, void *, unsigned );
+static int retry_writev(int, struct iovec *, int );
+static int read_string(int, uschar **);
+static int write_string(int, const uschar *, int);
+
+#endif
+
+
+/* A dummy function that always fails if pwcheck support is not
+wanted. */
+
+#ifndef CYRUS_PWCHECK_SOCKET
+int pwcheck_verify_password(const char *userid,
+                            const char *passwd,
+                            const char **reply)
+{
+userid = userid;  /* Keep picky compilers happy */
+passwd = passwd;
+*reply = "pwcheck support is not included in this Exim binary";
+return PWCHECK_FAIL;
+}
+
+
+/* This is the real function */
+
+#else
+
+ /* taken from cyrus-sasl file checkpw.c */
+ /* pwcheck daemon-authenticated login */
+ int pwcheck_verify_password(const char *userid,
+                                  const char *passwd,
+                                  const char **reply)
+ {
+     int s, start, r, n;
+     struct sockaddr_un srvaddr;
+     struct iovec iov[2];
+     static char response[1024];
+
+     *reply = NULL;
+
+     s = socket(AF_UNIX, SOCK_STREAM, 0);
+     if (s == -1) { return PWCHECK_FAIL; }
+
+     memset(CS &srvaddr, 0, sizeof(srvaddr));
+     srvaddr.sun_family = AF_UNIX;
+     strncpy(srvaddr.sun_path, CYRUS_PWCHECK_SOCKET, sizeof(srvaddr.sun_path));
+     r = connect(s, (struct sockaddr *)&srvaddr, sizeof(srvaddr));
+     if (r == -1) {
+        DEBUG(D_auth)
+            debug_printf("Cannot connect to pwcheck daemon (at '%s')\n",CYRUS_PWCHECK_SOCKET);
+       *reply = "cannot connect to pwcheck daemon";
+       return PWCHECK_FAIL;
+     }
+
+     iov[0].iov_base = CS userid;
+     iov[0].iov_len = strlen(userid)+1;
+     iov[1].iov_base = CS passwd;
+     iov[1].iov_len = strlen(passwd)+1;
+
+     retry_writev(s, iov, 2);
+
+     start = 0;
+     while (start < sizeof(response) - 1) {
+       n = read(s, response+start, sizeof(response) - 1 - start);
+       if (n < 1) break;
+       start += n;
+     }
+
+     (void)close(s);
+
+     if (start > 1 && !strncmp(response, "OK", 2)) {
+       return PWCHECK_OK;
+     }
+
+     response[start] = '\0';
+     *reply = response;
+     return PWCHECK_NO;
+ }
+
+#endif
+
+
+
+ /* A dummy function that always fails if saslauthd support is not
+wanted. */
+
+#ifndef CYRUS_SASLAUTHD_SOCKET
+int saslauthd_verify_password(const uschar *userid,
+                const uschar *passwd,
+                const uschar *service,
+                const uschar *realm,
+                const uschar **reply)
+{
+userid = userid;  /* Keep picky compilers happy */
+passwd = passwd;
+service = service;
+realm = realm;
+*reply = US"saslauthd support is not included in this Exim binary";
+return PWCHECK_FAIL;
+}
+
+
+/* This is the real function */
+
+#else
+ /* written from scratch  */
+ /* saslauthd daemon-authenticated login */
+
+int saslauthd_verify_password(const uschar *userid,
+                const uschar *password,
+                const uschar *service,
+                const uschar *realm,
+                const uschar **reply)
+{
+    uschar *daemon_reply = NULL;
+    int s, r;
+    struct sockaddr_un srvaddr;
+
+    DEBUG(D_auth)
+       debug_printf("saslauthd userid='%s' servicename='%s'"
+                    " realm='%s'\n", userid, service, realm );
+
+    *reply = NULL;
+
+    s = socket(AF_UNIX, SOCK_STREAM, 0);
+    if (s == -1) {
+       *reply = CUstrerror(errno);
+       return PWCHECK_FAIL;
+    }
+
+    memset(CS &srvaddr, 0, sizeof(srvaddr));
+    srvaddr.sun_family = AF_UNIX;
+    strncpy(srvaddr.sun_path, CYRUS_SASLAUTHD_SOCKET,
+            sizeof(srvaddr.sun_path));
+    r = connect(s, (struct sockaddr *)&srvaddr, sizeof(srvaddr));
+    if (r == -1) {
+       DEBUG(D_auth)
+            debug_printf("Cannot connect to saslauthd daemon (at '%s'): %s\n",
+                         CYRUS_SASLAUTHD_SOCKET, strerror(errno));
+       *reply = string_sprintf("cannot connect to saslauthd daemon at "
+                               "%s: %s", CYRUS_SASLAUTHD_SOCKET,
+                               strerror(errno));
+       return PWCHECK_FAIL;
+    }
+
+    if ( write_string(s, userid, Ustrlen(userid)) < 0) {
+        DEBUG(D_auth)
+            debug_printf("Failed to send userid to saslauthd daemon \n");
+        (void)close(s);
+        return PWCHECK_FAIL;
+    }
+
+    if ( write_string(s, password, Ustrlen(password)) < 0) {
+        DEBUG(D_auth)
+            debug_printf("Failed to send password to saslauthd daemon \n");
+        (void)close(s);
+        return PWCHECK_FAIL;
+    }
+
+    memset((void *)password, 0, Ustrlen(password));
+
+    if ( write_string(s, service, Ustrlen(service)) < 0) {
+        DEBUG(D_auth)
+            debug_printf("Failed to send service name to saslauthd daemon \n");
+        (void)close(s);
+        return PWCHECK_FAIL;
+    }
+
+    if ( write_string(s, realm, Ustrlen(realm)) < 0) {
+        DEBUG(D_auth)
+            debug_printf("Failed to send realm to saslauthd daemon \n");
+        (void)close(s);
+        return PWCHECK_FAIL;
+    }
+
+    if ( read_string(s, &daemon_reply ) < 2) {
+        DEBUG(D_auth)
+            debug_printf("Corrupted answer '%s' received. \n", daemon_reply);
+        (void)close(s);
+        return PWCHECK_FAIL;
+    }
+
+    (void)close(s);
+
+    DEBUG(D_auth)
+        debug_printf("Answer '%s' received. \n", daemon_reply);
+
+    *reply = daemon_reply;
+
+    if ( (daemon_reply[0] == 'O') && (daemon_reply[1] == 'K') )
+        return PWCHECK_OK;
+
+    if ( (daemon_reply[0] == 'N') && (daemon_reply[1] == 'O') )
+        return PWCHECK_NO;
+
+    return PWCHECK_FAIL;
+}
+
+#endif
+
+
+/* helper functions */
+#if defined(CYRUS_PWCHECK_SOCKET) || defined(CYRUS_SASLAUTHD_SOCKET)
+
+#define MAX_REQ_LEN 1024
+
+/* written from scratch */
+
+/* FUNCTION: read_string */
+
+/* SYNOPSIS
+ * read a sasld-style counted string into
+ * store-allocated buffer, set pointer to the buffer,
+ * return number of bytes read or -1 on failure.
+ * END SYNOPSIS */
+
+static int read_string(int fd, uschar **retval) {
+    unsigned short count;
+    int rc;
+
+    rc = (retry_read(fd, &count, sizeof(count)) < (int) sizeof(count));
+    if (!rc) {
+        count = ntohs(count);
+        if (count > MAX_REQ_LEN) {
+            return -1;
+        } else {
+	    /* Assume the file is trusted, so no tainting */
+            *retval = store_get(count + 1, FALSE);
+            rc = (retry_read(fd, *retval, count) < (int) count);
+            (*retval)[count] = '\0';
+            return count;
+        }
+    }
+    return -1;
+}
+
+
+/* FUNCTION: write_string */
+
+/* SYNOPSIS
+ * write a sasld-style counted string into given fd
+ * written bytes on success, -1 on failure.
+ * END SYNOPSIS */
+
+static int write_string(int fd, const uschar *string, int len) {
+    unsigned short count;
+    int rc;
+    struct iovec iov[2];
+
+    count = htons(len);
+
+    iov[0].iov_base = (void *) &count;
+    iov[0].iov_len = sizeof(count);
+    iov[1].iov_base = (void *) string;
+    iov[1].iov_len = len;
+
+    rc = retry_writev(fd, iov, 2);
+
+    return rc;
+}
+
+
+/* taken from cyrus-sasl file saslauthd/saslauthd-unix.c  */
+
+/* FUNCTION: retry_read */
+
+/* SYNOPSIS
+ * Keep calling the read() system call with 'fd', 'buf', and 'nbyte'
+ * until all the data is read in or an error occurs.
+ * END SYNOPSIS */
+static int retry_read(int fd, void *inbuf, unsigned nbyte)
+{
+    int n;
+    int nread = 0;
+    char *buf = CS inbuf;
+
+    if (nbyte == 0) return 0;
+
+    for (;;) {
+       n = read(fd, buf, nbyte);
+       if (n == 0) {
+           /* end of file */
+           return -1;
+       }
+       if (n == -1) {
+           if (errno == EINTR) continue;
+           return -1;
+       }
+
+       nread += n;
+
+       if (n >= (int) nbyte) return nread;
+
+       buf += n;
+       nbyte -= n;
+    }
+}
+
+/* END FUNCTION: retry_read */
+
+/* FUNCTION: retry_writev */
+
+/* SYNOPSIS
+ * Keep calling the writev() system call with 'fd', 'iov', and 'iovcnt'
+ * until all the data is written out or an error occurs.
+ * END SYNOPSIS */
+
+static int     /* R: bytes written, or -1 on error */
+retry_writev (
+  /* PARAMETERS */
+  int fd,                              /* I: fd to write on */
+  struct iovec *iov,                   /* U: iovec array base
+                                        *    modified as data written */
+  int iovcnt                           /* I: number of iovec entries */
+  /* END PARAMETERS */
+  )
+{
+    /* VARIABLES */
+    int n;                             /* return value from writev() */
+    int i;                             /* loop counter */
+    int written;                       /* bytes written so far */
+    static int iov_max;                        /* max number of iovec entries */
+    /* END VARIABLES */
+
+    /* initialization */
+#ifdef MAXIOV
+    iov_max = MAXIOV;
+#else /* ! MAXIOV */
+# ifdef IOV_MAX
+    iov_max = IOV_MAX;
+# else /* ! IOV_MAX */
+    iov_max = 8192;
+# endif /* ! IOV_MAX */
+#endif /* ! MAXIOV */
+    written = 0;
+
+    for (;;) {
+
+       while (iovcnt && iov[0].iov_len == 0) {
+           iov++;
+           iovcnt--;
+       }
+
+       if (!iovcnt) {
+           return written;
+       }
+
+       n = writev(fd, iov, iovcnt > iov_max ? iov_max : iovcnt);
+       if (n == -1) {
+           if (errno == EINVAL && iov_max > 10) {
+               iov_max /= 2;
+               continue;
+           }
+           if (errno == EINTR) {
+               continue;
+           }
+           return -1;
+       } else {
+           written += n;
+       }
+
+       for (i = 0; i < iovcnt; i++) {
+           if (iov[i].iov_len > (unsigned) n) {
+               iov[i].iov_base = CS iov[i].iov_base + n;
+               iov[i].iov_len -= n;
+               break;
+           }
+           n -= iov[i].iov_len;
+           iov[i].iov_len = 0;
+       }
+
+       if (i == iovcnt) {
+           return written;
+       }
+    }
+    /* NOTREACHED */
+}
+
+/* END FUNCTION: retry_writev */
+#endif
+
+/* End of auths/pwcheck.c */
diff --git a/src/auths/pwcheck.h b/src/auths/pwcheck.h
new file mode 100644
index 0000000..1287ea2
--- /dev/null
+++ b/src/auths/pwcheck.h
@@ -0,0 +1,27 @@
+/*************************************************
+*     Exim - an Internet mail transport agent    *
+*************************************************/
+
+/* Copyright (c) University of Cambridge 1995 - 2009 */
+/* See the file NOTICE for conditions of use and distribution. */
+
+/* This file provides support for authentication via the Cyrus SASL pwcheck
+daemon (whence its name) and the newer saslauthd daemon. */
+
+/* Error codes used internally within the authentication functions */
+
+/* PWCHECK_OK   - auth successful
+   PWCHECK_NO   - access denied
+   PWCHECK_FAIL - [temporary] failure */
+
+#define PWCHECK_OK   0
+#define PWCHECK_NO   1
+#define PWCHECK_FAIL 2
+
+/* Cyrus functions for doing the business. */
+
+extern int pwcheck_verify_password(const char *, const char *, const char **);
+extern int saslauthd_verify_password(const uschar *, const uschar *,
+           const uschar *, const uschar *, const uschar **);
+
+/* End of pwcheck.h */
diff --git a/src/auths/spa.c b/src/auths/spa.c
new file mode 100644
index 0000000..ff90d33
--- /dev/null
+++ b/src/auths/spa.c
@@ -0,0 +1,376 @@
+/*************************************************
+*     Exim - an Internet mail transport agent    *
+*************************************************/
+
+/* Copyright (c) University of Cambridge 1995 - 2018 */
+/* Copyright (c) The Exim Maintainers 2020 */
+/* See the file NOTICE for conditions of use and distribution. */
+
+/* This file, which provides support for Microsoft's Secure Password
+Authentication, was contributed by Marc Prud'hommeaux. Tom Kistner added SPA
+server support. I (PH) have only modified it in very trivial ways.
+
+References:
+  http://www.innovation.ch/java/ntlm.html
+  http://www.kuro5hin.org/story/2002/4/28/1436/66154
+  http://download.microsoft.com/download/9/5/e/95ef66af-9026-4bb0-a41d-a4f81802d92c/%5bMS-SMTP%5d.pdf
+
+ * It seems that some systems have existing but different definitions of some
+ * of the following types. I received a complaint about "int16" causing
+ * compilation problems. So I (PH) have renamed them all, to be on the safe
+ * side, by adding 'x' on the end. See auths/auth-spa.h.
+
+ * typedef signed short int16;
+ * typedef unsigned short uint16;
+ * typedef unsigned uint32;
+ * typedef unsigned char  uint8;
+
+07-August-2003:  PH: Patched up the code to avoid assert bombouts for stupid
+                     input data. Find appropriate comment by grepping for "PH".
+16-October-2006: PH: Added a call to auth_check_serv_cond() at the end
+05-June-2010:    PP: handle SASL initial response
+*/
+
+
+#include "../exim.h"
+#include "spa.h"
+
+/* #define DEBUG_SPA */
+
+#ifdef DEBUG_SPA
+#define DSPA(x,y,z)   debug_printf(x,y,z)
+#else
+#define DSPA(x,y,z)
+#endif
+
+/* Options specific to the spa authentication mechanism. */
+
+optionlist auth_spa_options[] = {
+  { "client_domain",             opt_stringptr,
+      OPT_OFF(auth_spa_options_block, spa_domain) },
+  { "client_password",           opt_stringptr,
+      OPT_OFF(auth_spa_options_block, spa_password) },
+  { "client_username",           opt_stringptr,
+      OPT_OFF(auth_spa_options_block, spa_username) },
+  { "server_password",           opt_stringptr,
+      OPT_OFF(auth_spa_options_block, spa_serverpassword) }
+};
+
+/* Size of the options list. An extern variable has to be used so that its
+address can appear in the tables drtables.c. */
+
+int auth_spa_options_count =
+  sizeof(auth_spa_options)/sizeof(optionlist);
+
+/* Default private options block for the condition authentication method. */
+
+auth_spa_options_block auth_spa_option_defaults = {
+  NULL,              /* spa_password */
+  NULL,              /* spa_username */
+  NULL,              /* spa_domain */
+  NULL               /* spa_serverpassword (for server side use) */
+};
+
+
+#ifdef MACRO_PREDEF
+
+/* Dummy values */
+void auth_spa_init(auth_instance *ablock) {}
+int auth_spa_server(auth_instance *ablock, uschar *data) {return 0;}
+int auth_spa_client(auth_instance *ablock, void * sx, int timeout,
+    uschar *buffer, int buffsize) {return 0;}
+
+#else   /*!MACRO_PREDEF*/
+
+
+
+
+/*************************************************
+*          Initialization entry point            *
+*************************************************/
+
+/* Called for each instance, after its options have been read, to
+enable consistency checks to be done, or anything else that needs
+to be set up. */
+
+void
+auth_spa_init(auth_instance *ablock)
+{
+auth_spa_options_block *ob =
+  (auth_spa_options_block *)(ablock->options_block);
+
+/* The public name defaults to the authenticator name */
+
+if (ablock->public_name == NULL) ablock->public_name = ablock->name;
+
+/* Both username and password must be set for a client */
+
+if ((ob->spa_username == NULL) != (ob->spa_password == NULL))
+  log_write(0, LOG_PANIC_DIE|LOG_CONFIG_FOR, "%s authenticator:\n  "
+      "one of client_username and client_password cannot be set without "
+      "the other", ablock->name);
+ablock->client = ob->spa_username != NULL;
+
+/* For a server we have just one option */
+
+ablock->server = ob->spa_serverpassword != NULL;
+}
+
+
+
+/*************************************************
+*             Server entry point                 *
+*************************************************/
+
+/* For interface, see auths/README */
+
+#define CVAL(buf,pos) ((US (buf))[pos])
+#define PVAL(buf,pos) ((unsigned)CVAL(buf,pos))
+#define SVAL(buf,pos) (PVAL(buf,pos)|PVAL(buf,(pos)+1)<<8)
+#define IVAL(buf,pos) (SVAL(buf,pos)|SVAL(buf,(pos)+2)<<16)
+
+int
+auth_spa_server(auth_instance *ablock, uschar *data)
+{
+auth_spa_options_block *ob = (auth_spa_options_block *)(ablock->options_block);
+uint8x lmRespData[24];
+uint8x ntRespData[24];
+SPAAuthRequest request;
+SPAAuthChallenge challenge;
+SPAAuthResponse  response;
+SPAAuthResponse  *responseptr = &response;
+uschar msgbuf[2048];
+uschar *clearpass, *s;
+unsigned off;
+
+/* send a 334, MS Exchange style, and grab the client's request,
+unless we already have it via an initial response. */
+
+if (!*data && auth_get_no64_data(&data, US"NTLM supported") != OK)
+  return FAIL;
+
+if (spa_base64_to_bits(CS &request, sizeof(request), CCS data) < 0)
+  {
+  DEBUG(D_auth) debug_printf("auth_spa_server(): bad base64 data in "
+    "request: %s\n", data);
+  return FAIL;
+  }
+
+/* create a challenge and send it back */
+
+spa_build_auth_challenge(&request, &challenge);
+spa_bits_to_base64(msgbuf, US &challenge, spa_request_length(&challenge));
+
+if (auth_get_no64_data(&data, msgbuf) != OK)
+  return FAIL;
+
+/* dump client response */
+if (spa_base64_to_bits(CS &response, sizeof(response), CCS data) < 0)
+  {
+  DEBUG(D_auth) debug_printf("auth_spa_server(): bad base64 data in "
+    "response: %s\n", data);
+  return FAIL;
+  }
+
+/***************************************************************
+PH 07-Aug-2003: The original code here was this:
+
+Ustrcpy(msgbuf, unicodeToString(((char*)responseptr) +
+  IVAL(&responseptr->uUser.offset,0),
+  SVAL(&responseptr->uUser.len,0)/2) );
+
+However, if the response data is too long, unicodeToString bombs out on
+an assertion failure. It uses a 1024 fixed buffer. Bombing out is not a good
+idea. It's too messy to try to rework that function to return an error because
+it is called from a number of other places in the auth-spa.c module. Instead,
+since it is a very small function, I reproduce its code here, with a size check
+that causes failure if the size of msgbuf is exceeded. ****/
+
+  {
+  int i;
+  char * p;
+  int len = SVAL(&responseptr->uUser.len,0)/2;
+
+  if (  (off = IVAL(&responseptr->uUser.offset,0)) >= sizeof(SPAAuthResponse)
+     || len >= sizeof(responseptr->buffer)/2
+     || (p = (CS responseptr) + off) + len*2 >= CS (responseptr+1)
+     )
+    {
+    DEBUG(D_auth)
+      debug_printf("auth_spa_server(): bad uUser spec in response\n");
+    return FAIL;
+    }
+
+  if (len + 1 >= sizeof(msgbuf)) return FAIL;
+  for (i = 0; i < len; ++i)
+    {
+    msgbuf[i] = *p & 0x7f;
+    p += 2;
+    }
+  msgbuf[i] = 0;
+  }
+
+/***************************************************************/
+
+/* Put the username in $auth1 and $1. The former is now the preferred variable;
+the latter is the original variable. These have to be out of stack memory, and
+need to be available once known even if not authenticated, for error messages
+(server_set_id, which only makes it to authenticated_id if we return OK) */
+
+auth_vars[0] = expand_nstring[1] = string_copy(msgbuf);
+expand_nlength[1] = Ustrlen(msgbuf);
+expand_nmax = 1;
+
+debug_print_string(ablock->server_debug_string);    /* customized debug */
+
+/* look up password */
+
+if (!(clearpass = expand_string(ob->spa_serverpassword)))
+  if (f.expand_string_forcedfail)
+    {
+    DEBUG(D_auth) debug_printf("auth_spa_server(): forced failure while "
+      "expanding spa_serverpassword\n");
+    return FAIL;
+    }
+  else
+    {
+    DEBUG(D_auth) debug_printf("auth_spa_server(): error while expanding "
+      "spa_serverpassword: %s\n", expand_string_message);
+    return DEFER;
+    }
+
+/* create local hash copy */
+
+spa_smb_encrypt(clearpass, challenge.challengeData, lmRespData);
+spa_smb_nt_encrypt(clearpass, challenge.challengeData, ntRespData);
+
+/* compare NT hash (LM may not be available) */
+
+off = IVAL(&responseptr->ntResponse.offset,0);
+if (off >= sizeof(SPAAuthResponse) - 24)
+  {
+  DEBUG(D_auth)
+    debug_printf("auth_spa_server(): bad ntRespData spec in response\n");
+  return FAIL;
+  }
+s = (US responseptr) + off;
+
+if (memcmp(ntRespData, s, 24) == 0)
+  return auth_check_serv_cond(ablock);	/* success. we have a winner. */
+
+  /* Expand server_condition as an authorization check (PH) */
+
+return FAIL;
+}
+
+
+/*************************************************
+*              Client entry point                *
+*************************************************/
+
+/* For interface, see auths/README */
+
+int
+auth_spa_client(
+  auth_instance *ablock,                 /* authenticator block */
+  void * sx,				 /* connection */
+  int timeout,                           /* command timeout */
+  uschar *buffer,                        /* buffer for reading response */
+  int buffsize)                          /* size of buffer */
+{
+auth_spa_options_block *ob =
+       (auth_spa_options_block *)(ablock->options_block);
+SPAAuthRequest   request;
+SPAAuthChallenge challenge;
+SPAAuthResponse  response;
+char msgbuf[2048];
+char *domain = NULL;
+char *username, *password;
+
+/* Code added by PH to expand the options */
+
+*buffer = 0;    /* Default no message when cancelled */
+
+if (!(username = CS expand_string(ob->spa_username)))
+  {
+  if (f.expand_string_forcedfail) return CANCELLED;
+  string_format(buffer, buffsize, "expansion of \"%s\" failed in %s "
+   "authenticator: %s", ob->spa_username, ablock->name,
+   expand_string_message);
+  return ERROR;
+  }
+
+if (!(password = CS expand_string(ob->spa_password)))
+  {
+  if (f.expand_string_forcedfail) return CANCELLED;
+  string_format(buffer, buffsize, "expansion of \"%s\" failed in %s "
+   "authenticator: %s", ob->spa_password, ablock->name,
+   expand_string_message);
+  return ERROR;
+  }
+
+if (ob->spa_domain)
+  if (!(domain = CS expand_string(ob->spa_domain)))
+    {
+    if (f.expand_string_forcedfail) return CANCELLED;
+    string_format(buffer, buffsize, "expansion of \"%s\" failed in %s "
+		  "authenticator: %s", ob->spa_domain, ablock->name,
+		  expand_string_message);
+    return ERROR;
+    }
+
+/* Original code */
+
+if (smtp_write_command(sx, SCMD_FLUSH, "AUTH %s\r\n", ablock->public_name) < 0)
+  return FAIL_SEND;
+
+/* wait for the 3XX OK message */
+if (!smtp_read_response(sx, US buffer, buffsize, '3', timeout))
+  return FAIL;
+
+DSPA("\n\n%s authenticator: using domain %s\n\n", ablock->name, domain);
+
+spa_build_auth_request(&request, CS username, domain);
+spa_bits_to_base64(US msgbuf, US &request, spa_request_length(&request));
+
+DSPA("\n\n%s authenticator: sending request (%s)\n\n", ablock->name, msgbuf);
+
+/* send the encrypted password */
+if (smtp_write_command(sx, SCMD_FLUSH, "%s\r\n", msgbuf) < 0)
+  return FAIL_SEND;
+
+/* wait for the auth challenge */
+if (!smtp_read_response(sx, US buffer, buffsize, '3', timeout))
+  return FAIL;
+
+/* convert the challenge into the challenge struct */
+DSPA("\n\n%s authenticator: challenge (%s)\n\n", ablock->name, buffer + 4);
+spa_base64_to_bits(CS (&challenge), sizeof(challenge), CCS (buffer + 4));
+
+spa_build_auth_response(&challenge, &response, CS username, CS password);
+spa_bits_to_base64(US msgbuf, US &response, spa_request_length(&response));
+DSPA("\n\n%s authenticator: challenge response (%s)\n\n", ablock->name, msgbuf);
+
+/* send the challenge response */
+if (smtp_write_command(sx, SCMD_FLUSH, "%s\r\n", msgbuf) < 0)
+       return FAIL_SEND;
+
+/* If we receive a success response from the server, authentication
+has succeeded. There may be more data to send, but is there any point
+in provoking an error here? */
+
+if (smtp_read_response(sx, US buffer, buffsize, '2', timeout))
+  return OK;
+
+/* Not a success response. If errno != 0 there is some kind of transmission
+error. Otherwise, check the response code in the buffer. If it starts with
+'3', more data is expected. */
+
+if (errno != 0 || buffer[0] != '3')
+  return FAIL;
+
+return FAIL;
+}
+
+#endif   /*!MACRO_PREDEF*/
+/* End of spa.c */
diff --git a/src/auths/spa.h b/src/auths/spa.h
new file mode 100644
index 0000000..ca93469
--- /dev/null
+++ b/src/auths/spa.h
@@ -0,0 +1,38 @@
+/*************************************************
+*     Exim - an Internet mail transport agent    *
+*************************************************/
+
+/* Copyright (c) University of Cambridge 1995 - 2009 */
+/* See the file NOTICE for conditions of use and distribution. */
+
+/* This file, which provides support for Microsoft's Secure Password
+Authentication, was contributed by Marc Prud'hommeaux. */
+
+
+#include "auth-spa.h"
+
+/* Private structure for the private options. */
+
+typedef struct {
+  uschar *spa_username;
+  uschar *spa_password;
+  uschar *spa_domain;
+  uschar *spa_serverpassword;
+} auth_spa_options_block;
+
+/* Data for reading the private options. */
+
+extern optionlist auth_spa_options[];
+extern int auth_spa_options_count;
+
+/* Block containing default values. */
+
+extern auth_spa_options_block auth_spa_option_defaults;
+
+/* The entry points for the mechanism */
+
+extern void auth_spa_init(auth_instance *);
+extern int auth_spa_server(auth_instance *, uschar *);
+extern int auth_spa_client(auth_instance *, void *, int, uschar *, int);
+
+/* End of spa.h */
diff --git a/src/auths/tls.c b/src/auths/tls.c
new file mode 100644
index 0000000..325e7b4
--- /dev/null
+++ b/src/auths/tls.c
@@ -0,0 +1,94 @@
+/*************************************************
+*     Exim - an Internet mail transport agent    *
+*************************************************/
+
+/* Copyright (c) Jeremy Harris 1995 - 2020 */
+/* See the file NOTICE for conditions of use and distribution. */
+
+/* This file provides an Exim authenticator driver for
+a server to verify a client SSL certificate
+*/
+
+
+#include "../exim.h"
+#include "tls.h"
+
+/* Options specific to the tls authentication mechanism. */
+
+optionlist auth_tls_options[] = {
+  { "server_param",     opt_stringptr,
+      OPT_OFF(auth_tls_options_block, server_param1) },
+  { "server_param1",    opt_stringptr,
+      OPT_OFF(auth_tls_options_block, server_param1) },
+  { "server_param2",    opt_stringptr,
+      OPT_OFF(auth_tls_options_block, server_param2) },
+  { "server_param3",    opt_stringptr,
+      OPT_OFF(auth_tls_options_block, server_param3) },
+};
+
+/* Size of the options list. An extern variable has to be used so that its
+address can appear in the tables drtables.c. */
+
+int auth_tls_options_count = nelem(auth_tls_options);
+
+/* Default private options block for the authentication method. */
+
+auth_tls_options_block auth_tls_option_defaults = {
+    NULL,	/* server_param1 */
+    NULL,	/* server_param2 */
+    NULL,	/* server_param3 */
+};
+
+
+#ifdef MACRO_PREDEF
+
+/* Dummy values */
+void auth_tls_init(auth_instance *ablock) {}
+int auth_tls_server(auth_instance *ablock, uschar *data) {return 0;}
+int auth_tls_client(auth_instance *ablock, void * sx,
+  int timeout, uschar *buffer, int buffsize) {return 0;}
+
+#else   /*!MACRO_PREDEF*/
+
+
+
+
+/*************************************************
+*          Initialization entry point            *
+*************************************************/
+
+/* Called for each instance, after its options have been read, to
+enable consistency checks to be done, or anything else that needs
+to be set up. */
+
+void
+auth_tls_init(auth_instance *ablock)
+{
+ablock->public_name = ablock->name;	/* needed for core code */
+}
+
+
+
+/*************************************************
+*             Server entry point                 *
+*************************************************/
+
+/* For interface, see auths/README */
+
+int
+auth_tls_server(auth_instance *ablock, uschar *data)
+{
+auth_tls_options_block * ob = (auth_tls_options_block *)ablock->options_block;
+
+if (ob->server_param1)
+  auth_vars[expand_nmax++] = expand_string(ob->server_param1);
+if (ob->server_param2)
+  auth_vars[expand_nmax++] = expand_string(ob->server_param2);
+if (ob->server_param3)
+  auth_vars[expand_nmax++] = expand_string(ob->server_param3);
+return auth_check_serv_cond(ablock);
+}
+
+
+#endif   /*!MACRO_PREDEF*/
+/* End of tls.c */
diff --git a/src/auths/tls.h b/src/auths/tls.h
new file mode 100644
index 0000000..7aa95b6
--- /dev/null
+++ b/src/auths/tls.h
@@ -0,0 +1,30 @@
+/*************************************************
+*     Exim - an Internet mail transport agent    *
+*************************************************/
+
+/* Copyright (c) Jeremy Harris 2015 */
+/* See the file NOTICE for conditions of use and distribution. */
+
+/* Private structure for the private options. */
+
+typedef struct {
+  uschar * server_param1;
+  uschar * server_param2;
+  uschar * server_param3;
+} auth_tls_options_block;
+
+/* Data for reading the private options. */
+
+extern optionlist auth_tls_options[];
+extern int auth_tls_options_count;
+
+/* Block containing default values. */
+
+extern auth_tls_options_block auth_tls_option_defaults;
+
+/* The entry points for the mechanism */
+
+extern void auth_tls_init(auth_instance *);
+extern int auth_tls_server(auth_instance *, uschar *);
+
+/* End of tls.h */
diff --git a/src/auths/xtextdecode.c b/src/auths/xtextdecode.c
new file mode 100644
index 0000000..95cf5da
--- /dev/null
+++ b/src/auths/xtextdecode.c
@@ -0,0 +1,57 @@
+/*************************************************
+*     Exim - an Internet mail transport agent    *
+*************************************************/
+
+/* Copyright (c) University of Cambridge 1995 - 2009 */
+/* See the file NOTICE for conditions of use and distribution. */
+
+#include "../exim.h"
+
+
+/*************************************************
+*          Decode byte-string in xtext           *
+*************************************************/
+
+/* This function decodes a string in xtextformat as defined in RFC 1891 and
+required by the SMTP AUTH extension (RFC 2554). We put the result in a piece of
+store of equal length - it cannot be longer than this. Although in general the
+result of decoding an xtext may be binary, in the context in which it is used
+by Exim (for decoding the value of AUTH on a MAIL command), the result is
+expected to be an addr-spec. We therefore add on a terminating zero, for
+convenience.
+
+Arguments:
+  code        points to the coded string, zero-terminated
+  ptr         where to put the pointer to the result, which is in
+              dynamic store
+
+Returns:      the number of bytes in the result, excluding the final zero;
+              -1 if the input is malformed
+*/
+
+int
+auth_xtextdecode(uschar *code, uschar **ptr)
+{
+register int x;
+uschar *result = store_get(Ustrlen(code) + 1, is_tainted(code));
+*ptr = result;
+
+while ((x = (*code++)) != 0)
+  {
+  if (x < 33 || x > 127 || x == '=') return -1;
+  if (x == '+')
+    {
+    register int y;
+    if (!isxdigit((x = (*code++)))) return -1;
+    y = ((isdigit(x))? x - '0' : (tolower(x) - 'a' + 10)) << 4;
+    if (!isxdigit((x = (*code++)))) return -1;
+    *result++ = y | ((isdigit(x))? x - '0' : (tolower(x) - 'a' + 10));
+    }
+  else *result++ = x;
+  }
+
+*result = 0;
+return result - *ptr;
+}
+
+/* End of xtextdecode.c */
diff --git a/src/auths/xtextencode.c b/src/auths/xtextencode.c
new file mode 100644
index 0000000..30ff8f1
--- /dev/null
+++ b/src/auths/xtextencode.c
@@ -0,0 +1,57 @@
+/*************************************************
+*     Exim - an Internet mail transport agent    *
+*************************************************/
+
+/* Copyright (c) University of Cambridge 1995 - 2018 */
+/* See the file NOTICE for conditions of use and distribution. */
+
+#include "../exim.h"
+
+
+/*************************************************
+*          Encode byte-string in xtext           *
+*************************************************/
+
+/* This function encodes a string of bytes, containing any values whatsoever,
+as "xtext", as defined in RFC 1891 and required by the SMTP AUTH extension (RFC
+2554).
+
+Arguments:
+  clear       points to the clear text bytes
+  len         the number of bytes to encode
+
+Returns:      a pointer to the zero-terminated xtext string, which
+              is in working store
+*/
+
+uschar *
+auth_xtextencode(uschar *clear, int len)
+{
+uschar *code;
+uschar *p = US clear;
+uschar *pp;
+int c = len;
+int count = 1;
+register int x;
+
+/* We have to do a prepass to find out how many specials there are,
+in order to get the right amount of store. */
+
+while (c -- > 0)
+  count += ((x = *p++) < 33 || x > 127 || x == '+' || x == '=')? 3 : 1;
+
+pp = code = store_get(count, is_tainted(clear));
+
+p = US clear;
+c = len;
+while (c-- > 0)
+  if ((x = *p++) < 33 || x > 127 || x == '+' || x == '=')
+    pp += sprintf(CS pp, "+%.02x", x);   /* There's always room */
+  else
+    *pp++ = x;
+
+*pp = 0;
+return code;
+}
+
+/* End of xtextencode.c */