Adding upstream version 4.96.upstream/4.96upstream

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

1 files changed, 6068 insertions, 0 deletions

diff --git a/src/smtp_in.c b/src/smtp_in.c
new file mode 100644
index 0000000..edb0adf
--- /dev/null
+++ b/src/smtp_in.c
@@ -0,0 +1,6068 @@
+/*************************************************
+*     Exim - an Internet mail transport agent    *
+*************************************************/
+
+/* Copyright (c) The Exim Maintainers 2020 - 2022 */
+/* Copyright (c) University of Cambridge 1995 - 2018 */
+/* See the file NOTICE for conditions of use and distribution. */
+
+/* Functions for handling an incoming SMTP call. */
+
+
+#include "exim.h"
+#include <assert.h>
+
+
+/* Initialize for TCP wrappers if so configured. It appears that the macro
+HAVE_IPV6 is used in some versions of the tcpd.h header, so we unset it before
+including that header, and restore its value afterwards. */
+
+#ifdef USE_TCP_WRAPPERS
+
+  #if HAVE_IPV6
+  #define EXIM_HAVE_IPV6
+  #endif
+  #undef HAVE_IPV6
+  #include <tcpd.h>
+  #undef HAVE_IPV6
+  #ifdef EXIM_HAVE_IPV6
+  #define HAVE_IPV6 TRUE
+  #endif
+
+int allow_severity = LOG_INFO;
+int deny_severity  = LOG_NOTICE;
+uschar *tcp_wrappers_name;
+#endif
+
+
+/* Size of buffer for reading SMTP commands. We used to use 512, as defined
+by RFC 821. However, RFC 1869 specifies that this must be increased for SMTP
+commands that accept arguments, and this in particular applies to AUTH, where
+the data can be quite long.  More recently this value was 2048 in Exim;
+however, RFC 4954 (circa 2007) recommends 12288 bytes to handle AUTH.  Clients
+such as Thunderbird will send an AUTH with an initial-response for GSSAPI.
+The maximum size of a Kerberos ticket under Windows 2003 is 12000 bytes, and
+we need room to handle large base64-encoded AUTHs for GSSAPI.
+*/
+
+#define SMTP_CMD_BUFFER_SIZE  16384
+
+/* Size of buffer for reading SMTP incoming packets */
+
+#define IN_BUFFER_SIZE  8192
+
+/* Structure for SMTP command list */
+
+typedef struct {
+  const char *name;
+  int len;
+  short int cmd;
+  short int has_arg;
+  short int is_mail_cmd;
+} smtp_cmd_list;
+
+/* Codes for identifying commands. We order them so that those that come first
+are those for which synchronization is always required. Checking this can help
+block some spam.  */
+
+enum {
+  /* These commands are required to be synchronized, i.e. to be the last in a
+  block of commands when pipelining. */
+
+  HELO_CMD, EHLO_CMD, DATA_CMD, /* These are listed in the pipelining */
+  VRFY_CMD, EXPN_CMD, NOOP_CMD, /* RFC as requiring synchronization */
+  ETRN_CMD,                     /* This by analogy with TURN from the RFC */
+  STARTTLS_CMD,                 /* Required by the STARTTLS RFC */
+  TLS_AUTH_CMD,			/* auto-command at start of SSL */
+
+  /* This is a dummy to identify the non-sync commands when pipelining */
+
+  NON_SYNC_CMD_PIPELINING,
+
+  /* These commands need not be synchronized when pipelining */
+
+  MAIL_CMD, RCPT_CMD, RSET_CMD,
+
+  /* This is a dummy to identify the non-sync commands when not pipelining */
+
+  NON_SYNC_CMD_NON_PIPELINING,
+
+  /* RFC3030 section 2: "After all MAIL and RCPT responses are collected and
+  processed the message is sent using a series of BDAT commands"
+  implies that BDAT should be synchronized.  However, we see Google, at least,
+  sending MAIL,RCPT,BDAT-LAST in a single packet, clearly not waiting for
+  processing of the RCPT response(s).  We shall do the same, and not require
+  synch for BDAT.  Worse, as the chunk may (very likely will) follow the
+  command-header in the same packet we cannot do the usual "is there any
+  follow-on data after the command line" even for non-pipeline mode.
+  So we'll need an explicit check after reading the expected chunk amount
+  when non-pipe, before sending the ACK. */
+
+  BDAT_CMD,
+
+  /* I have been unable to find a statement about the use of pipelining
+  with AUTH, so to be on the safe side it is here, though I kind of feel
+  it should be up there with the synchronized commands. */
+
+  AUTH_CMD,
+
+  /* I'm not sure about these, but I don't think they matter. */
+
+  QUIT_CMD, HELP_CMD,
+
+#ifdef SUPPORT_PROXY
+  PROXY_FAIL_IGNORE_CMD,
+#endif
+
+  /* These are specials that don't correspond to actual commands */
+
+  EOF_CMD, OTHER_CMD, BADARG_CMD, BADCHAR_CMD, BADSYN_CMD,
+  TOO_MANY_NONMAIL_CMD };
+
+
+/* This is a convenience macro for adding the identity of an SMTP command
+to the circular buffer that holds a list of the last n received. */
+
+#define HAD(n) \
+    smtp_connection_had[smtp_ch_index++] = n; \
+    if (smtp_ch_index >= SMTP_HBUFF_SIZE) smtp_ch_index = 0
+
+
+/*************************************************
+*                Local static variables          *
+*************************************************/
+
+static struct {
+  BOOL auth_advertised			:1;
+#ifndef DISABLE_TLS
+  BOOL tls_advertised			:1;
+#endif
+  BOOL dsn_advertised			:1;
+  BOOL esmtp				:1;
+  BOOL helo_verify_required		:1;
+  BOOL helo_verify			:1;
+  BOOL helo_seen			:1;
+  BOOL helo_accept_junk			:1;
+#ifndef DISABLE_PIPE_CONNECT
+  BOOL pipe_connect_acceptable		:1;
+#endif
+  BOOL rcpt_smtp_response_same		:1;
+  BOOL rcpt_in_progress			:1;
+  BOOL smtp_exit_function_called	:1;
+#ifdef SUPPORT_I18N
+  BOOL smtputf8_advertised		:1;
+#endif
+} fl = {
+  .helo_verify_required = FALSE,
+  .helo_verify = FALSE,
+  .smtp_exit_function_called = FALSE,
+};
+
+static auth_instance *authenticated_by;
+static int  count_nonmail;
+static int  nonmail_command_count;
+static int  synprot_error_count;
+static int  unknown_command_count;
+static int  sync_cmd_limit;
+static int  smtp_write_error = 0;
+
+static uschar *rcpt_smtp_response;
+static uschar *smtp_data_buffer;
+static uschar *smtp_cmd_data;
+
+/* We need to know the position of RSET, HELO, EHLO, AUTH, and STARTTLS. Their
+final fields of all except AUTH are forced TRUE at the start of a new message
+setup, to allow one of each between messages that is not counted as a nonmail
+command. (In fact, only one of HELO/EHLO is not counted.) Also, we have to
+allow a new EHLO after starting up TLS.
+
+AUTH is "falsely" labelled as a mail command initially, so that it doesn't get
+counted. However, the flag is changed when AUTH is received, so that multiple
+failing AUTHs will eventually hit the limit. After a successful AUTH, another
+AUTH is already forbidden. After a TLS session is started, AUTH's flag is again
+forced TRUE, to allow for the re-authentication that can happen at that point.
+
+QUIT is also "falsely" labelled as a mail command so that it doesn't up the
+count of non-mail commands and possibly provoke an error.
+
+tls_auth is a pseudo-command, never expected in input.  It is activated
+on TLS startup and looks for a tls authenticator. */
+
+static smtp_cmd_list cmd_list[] = {
+  /* name         len                     cmd     has_arg is_mail_cmd */
+
+  { "rset",       sizeof("rset")-1,       RSET_CMD, FALSE, FALSE },  /* First */
+  { "helo",       sizeof("helo")-1,       HELO_CMD, TRUE,  FALSE },
+  { "ehlo",       sizeof("ehlo")-1,       EHLO_CMD, TRUE,  FALSE },
+  { "auth",       sizeof("auth")-1,       AUTH_CMD, TRUE,  TRUE  },
+#ifndef DISABLE_TLS
+  { "starttls",   sizeof("starttls")-1,   STARTTLS_CMD, FALSE, FALSE },
+  { "tls_auth",   0,                      TLS_AUTH_CMD, FALSE, FALSE },
+#endif
+
+/* If you change anything above here, also fix the definitions below. */
+
+  { "mail from:", sizeof("mail from:")-1, MAIL_CMD, TRUE,  TRUE  },
+  { "rcpt to:",   sizeof("rcpt to:")-1,   RCPT_CMD, TRUE,  TRUE  },
+  { "data",       sizeof("data")-1,       DATA_CMD, FALSE, TRUE  },
+  { "bdat",       sizeof("bdat")-1,       BDAT_CMD, TRUE,  TRUE  },
+  { "quit",       sizeof("quit")-1,       QUIT_CMD, FALSE, TRUE  },
+  { "noop",       sizeof("noop")-1,       NOOP_CMD, TRUE,  FALSE },
+  { "etrn",       sizeof("etrn")-1,       ETRN_CMD, TRUE,  FALSE },
+  { "vrfy",       sizeof("vrfy")-1,       VRFY_CMD, TRUE,  FALSE },
+  { "expn",       sizeof("expn")-1,       EXPN_CMD, TRUE,  FALSE },
+  { "help",       sizeof("help")-1,       HELP_CMD, TRUE,  FALSE }
+};
+
+static smtp_cmd_list *cmd_list_end =
+  cmd_list + sizeof(cmd_list)/sizeof(smtp_cmd_list);
+
+#define CMD_LIST_RSET      0
+#define CMD_LIST_HELO      1
+#define CMD_LIST_EHLO      2
+#define CMD_LIST_AUTH      3
+#define CMD_LIST_STARTTLS  4
+#define CMD_LIST_TLS_AUTH  5
+
+/* This list of names is used for performing the smtp_no_mail logging action.
+It must be kept in step with the SCH_xxx enumerations. */
+
+uschar * smtp_names[] =
+  {
+  US"NONE", US"AUTH", US"DATA", US"BDAT", US"EHLO", US"ETRN", US"EXPN",
+  US"HELO", US"HELP", US"MAIL", US"NOOP", US"QUIT", US"RCPT", US"RSET",
+  US"STARTTLS", US"VRFY" };
+
+static uschar *protocols_local[] = {
+  US"local-smtp",        /* HELO */
+  US"local-smtps",       /* The rare case EHLO->STARTTLS->HELO */
+  US"local-esmtp",       /* EHLO */
+  US"local-esmtps",      /* EHLO->STARTTLS->EHLO */
+  US"local-esmtpa",      /* EHLO->AUTH */
+  US"local-esmtpsa"      /* EHLO->STARTTLS->EHLO->AUTH */
+  };
+static uschar *protocols[] = {
+  US"smtp",              /* HELO */
+  US"smtps",             /* The rare case EHLO->STARTTLS->HELO */
+  US"esmtp",             /* EHLO */
+  US"esmtps",            /* EHLO->STARTTLS->EHLO */
+  US"esmtpa",            /* EHLO->AUTH */
+  US"esmtpsa"            /* EHLO->STARTTLS->EHLO->AUTH */
+  };
+
+#define pnormal  0
+#define pextend  2
+#define pcrpted  1  /* added to pextend or pnormal */
+#define pauthed  2  /* added to pextend */
+
+/* Sanity check and validate optional args to MAIL FROM: envelope */
+enum {
+  ENV_MAIL_OPT_NULL,
+  ENV_MAIL_OPT_SIZE, ENV_MAIL_OPT_BODY, ENV_MAIL_OPT_AUTH,
+#ifndef DISABLE_PRDR
+  ENV_MAIL_OPT_PRDR,
+#endif
+  ENV_MAIL_OPT_RET, ENV_MAIL_OPT_ENVID,
+#ifdef SUPPORT_I18N
+  ENV_MAIL_OPT_UTF8,
+#endif
+  };
+typedef struct {
+  uschar *   name;  /* option requested during MAIL cmd */
+  int       value;  /* enum type */
+  BOOL need_value;  /* TRUE requires value (name=value pair format)
+                       FALSE is a singleton */
+  } env_mail_type_t;
+static env_mail_type_t env_mail_type_list[] = {
+    { US"SIZE",   ENV_MAIL_OPT_SIZE,   TRUE  },
+    { US"BODY",   ENV_MAIL_OPT_BODY,   TRUE  },
+    { US"AUTH",   ENV_MAIL_OPT_AUTH,   TRUE  },
+#ifndef DISABLE_PRDR
+    { US"PRDR",   ENV_MAIL_OPT_PRDR,   FALSE },
+#endif
+    { US"RET",    ENV_MAIL_OPT_RET,    TRUE },
+    { US"ENVID",  ENV_MAIL_OPT_ENVID,  TRUE },
+#ifdef SUPPORT_I18N
+    { US"SMTPUTF8",ENV_MAIL_OPT_UTF8,  FALSE },		/* rfc6531 */
+#endif
+    /* keep this the last entry */
+    { US"NULL",   ENV_MAIL_OPT_NULL,   FALSE },
+  };
+
+/* When reading SMTP from a remote host, we have to use our own versions of the
+C input-reading functions, in order to be able to flush the SMTP output only
+when about to read more data from the socket. This is the only way to get
+optimal performance when the client is using pipelining. Flushing for every
+command causes a separate packet and reply packet each time; saving all the
+responses up (when pipelining) combines them into one packet and one response.
+
+For simplicity, these functions are used for *all* SMTP input, not only when
+receiving over a socket. However, after setting up a secure socket (SSL), input
+is read via the OpenSSL library, and another set of functions is used instead
+(see tls.c).
+
+These functions are set in the receive_getc etc. variables and called with the
+same interface as the C functions. However, since there can only ever be
+one incoming SMTP call, we just use a single buffer and flags. There is no need
+to implement a complicated private FILE-like structure.*/
+
+static uschar *smtp_inbuffer;
+static uschar *smtp_inptr;
+static uschar *smtp_inend;
+static int     smtp_had_eof;
+static int     smtp_had_error;
+
+
+/* forward declarations */
+static int smtp_read_command(BOOL check_sync, unsigned buffer_lim);
+static int synprot_error(int type, int code, uschar *data, uschar *errmess);
+static void smtp_quit_handler(uschar **, uschar **);
+static void smtp_rset_handler(void);
+
+/*************************************************
+*          Log incomplete transactions           *
+*************************************************/
+
+/* This function is called after a transaction has been aborted by RSET, QUIT,
+connection drops or other errors. It logs the envelope information received
+so far in order to preserve address verification attempts.
+
+Argument:   string to indicate what aborted the transaction
+Returns:    nothing
+*/
+
+static void
+incomplete_transaction_log(uschar *what)
+{
+if (!sender_address				/* No transaction in progress */
+   || !LOGGING(smtp_incomplete_transaction))
+  return;
+
+/* Build list of recipients for logging */
+
+if (recipients_count > 0)
+  {
+  raw_recipients = store_get(recipients_count * sizeof(uschar *), GET_UNTAINTED);
+  for (int i = 0; i < recipients_count; i++)
+    raw_recipients[i] = recipients_list[i].address;
+  raw_recipients_count = recipients_count;
+  }
+
+log_write(L_smtp_incomplete_transaction, LOG_MAIN|LOG_SENDER|LOG_RECIPIENTS,
+  "%s incomplete transaction (%s)", host_and_ident(TRUE), what);
+}
+
+
+
+
+void
+smtp_command_timeout_exit(void)
+{
+log_write(L_lost_incoming_connection,
+	  LOG_MAIN, "SMTP command timeout on%s connection from %s",
+	  tls_in.active.sock >= 0 ? " TLS" : "", host_and_ident(FALSE));
+if (smtp_batched_input)
+  moan_smtp_batch(NULL, "421 SMTP command timeout"); /* Does not return */
+smtp_notquit_exit(US"command-timeout", US"421",
+  US"%s: SMTP command timeout - closing connection",
+  smtp_active_hostname);
+exim_exit(EXIT_FAILURE);
+}
+
+void
+smtp_command_sigterm_exit(void)
+{
+log_write(0, LOG_MAIN, "%s closed after SIGTERM", smtp_get_connection_info());
+if (smtp_batched_input)
+  moan_smtp_batch(NULL, "421 SIGTERM received");  /* Does not return */
+smtp_notquit_exit(US"signal-exit", US"421",
+  US"%s: Service not available - closing connection", smtp_active_hostname);
+exim_exit(EXIT_FAILURE);
+}
+
+void
+smtp_data_timeout_exit(void)
+{
+log_write(L_lost_incoming_connection,
+  LOG_MAIN, "SMTP data timeout (message abandoned) on connection from %s F=<%s>",
+  sender_fullhost ? sender_fullhost : US"local process", sender_address);
+receive_bomb_out(US"data-timeout", US"SMTP incoming data timeout");
+/* Does not return */
+}
+
+void
+smtp_data_sigint_exit(void)
+{
+log_write(0, LOG_MAIN, "%s closed after %s",
+  smtp_get_connection_info(), had_data_sigint == SIGTERM ? "SIGTERM":"SIGINT");
+receive_bomb_out(US"signal-exit",
+  US"Service not available - SIGTERM or SIGINT received");
+/* Does not return */
+}
+
+
+/******************************************************************************/
+/* SMTP input buffer handling.  Most of these are similar to stdio routines.  */
+
+static void
+smtp_buf_init(void)
+{
+/* Set up the buffer for inputting using direct read() calls, and arrange to
+call the local functions instead of the standard C ones.  Place a NUL at the
+end of the buffer to safety-stop C-string reads from it. */
+
+if (!(smtp_inbuffer = US malloc(IN_BUFFER_SIZE)))
+  log_write(0, LOG_MAIN|LOG_PANIC_DIE, "malloc() failed for SMTP input buffer");
+smtp_inbuffer[IN_BUFFER_SIZE-1] = '\0';
+
+smtp_inptr = smtp_inend = smtp_inbuffer;
+smtp_had_eof = smtp_had_error = 0;
+}
+
+
+
+/* Refill the buffer, and notify DKIM verification code.
+Return false for error or EOF.
+*/
+
+static BOOL
+smtp_refill(unsigned lim)
+{
+int rc, save_errno;
+
+if (!smtp_out) return FALSE;
+fflush(smtp_out);
+if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout);
+
+/* Limit amount read, so non-message data is not fed to DKIM.
+Take care to not touch the safety NUL at the end of the buffer. */
+
+rc = read(fileno(smtp_in), smtp_inbuffer, MIN(IN_BUFFER_SIZE-1, lim));
+save_errno = errno;
+if (smtp_receive_timeout > 0) ALARM_CLR(0);
+if (rc <= 0)
+  {
+  /* Must put the error text in fixed store, because this might be during
+  header reading, where it releases unused store above the header. */
+  if (rc < 0)
+    {
+    if (had_command_timeout)		/* set by signal handler */
+      smtp_command_timeout_exit();	/* does not return */
+    if (had_command_sigterm)
+      smtp_command_sigterm_exit();
+    if (had_data_timeout)
+      smtp_data_timeout_exit();
+    if (had_data_sigint)
+      smtp_data_sigint_exit();
+
+    smtp_had_error = save_errno;
+    smtp_read_error = string_copy_perm(
+      string_sprintf(" (error: %s)", strerror(save_errno)), FALSE);
+    }
+  else
+    smtp_had_eof = 1;
+  return FALSE;
+  }
+#ifndef DISABLE_DKIM
+dkim_exim_verify_feed(smtp_inbuffer, rc);
+#endif
+smtp_inend = smtp_inbuffer + rc;
+smtp_inptr = smtp_inbuffer;
+return TRUE;
+}
+
+
+/* Check if there is buffered data */
+
+BOOL
+smtp_hasc(void)
+{
+return smtp_inptr < smtp_inend;
+}
+
+/* SMTP version of getc()
+
+This gets the next byte from the SMTP input buffer. If the buffer is empty,
+it flushes the output, and refills the buffer, with a timeout. The signal
+handler is set appropriately by the calling function. This function is not used
+after a connection has negotiated itself into an TLS/SSL state.
+
+Arguments:  lim		Maximum amount to read/buffer
+Returns:    the next character or EOF
+*/
+
+int
+smtp_getc(unsigned lim)
+{
+if (!smtp_hasc() && !smtp_refill(lim)) return EOF;
+return *smtp_inptr++;
+}
+
+/* Get many bytes, refilling buffer if needed */
+
+uschar *
+smtp_getbuf(unsigned * len)
+{
+unsigned size;
+uschar * buf;
+
+if (!smtp_hasc() && !smtp_refill(*len))
+  { *len = 0; return NULL; }
+
+if ((size = smtp_inend - smtp_inptr) > *len) size = *len;
+buf = smtp_inptr;
+smtp_inptr += size;
+*len = size;
+return buf;
+}
+
+/* Copy buffered data to the dkim feed.
+Called, unless TLS, just before starting to read message headers. */
+
+void
+smtp_get_cache(unsigned lim)
+{
+#ifndef DISABLE_DKIM
+int n = smtp_inend - smtp_inptr;
+if (n > lim)
+  n = lim;
+if (n > 0)
+  dkim_exim_verify_feed(smtp_inptr, n);
+#endif
+}
+
+
+/* SMTP version of ungetc()
+Puts a character back in the input buffer. Only ever called once.
+
+Arguments:
+  ch           the character
+
+Returns:       the character
+*/
+
+int
+smtp_ungetc(int ch)
+{
+if (smtp_inptr <= smtp_inbuffer)	/* NB: NOT smtp_hasc() ! */
+  log_write(0, LOG_MAIN|LOG_PANIC_DIE, "buffer underflow in smtp_ungetc");
+
+*--smtp_inptr = ch;
+return ch;
+}
+
+
+/* SMTP version of feof()
+Tests for a previous EOF
+
+Arguments:     none
+Returns:       non-zero if the eof flag is set
+*/
+
+int
+smtp_feof(void)
+{
+return smtp_had_eof;
+}
+
+
+/* SMTP version of ferror()
+Tests for a previous read error, and returns with errno
+restored to what it was when the error was detected.
+
+Arguments:     none
+Returns:       non-zero if the error flag is set
+*/
+
+int
+smtp_ferror(void)
+{
+errno = smtp_had_error;
+return smtp_had_error;
+}
+
+
+/* Check if a getc will block or not */
+
+static BOOL
+smtp_could_getc(void)
+{
+int fd, rc;
+fd_set fds;
+struct timeval tzero = {.tv_sec = 0, .tv_usec = 0};
+
+if (smtp_inptr < smtp_inend)
+  return TRUE;
+
+fd = fileno(smtp_in);
+FD_ZERO(&fds);
+FD_SET(fd, &fds);
+rc = select(fd + 1, (SELECT_ARG2_TYPE *)&fds, NULL, NULL, &tzero);
+
+if (rc <= 0) return FALSE;     /* Not ready to read */
+rc = smtp_getc(GETC_BUFFER_UNLIMITED);
+if (rc < 0) return FALSE;      /* End of file or error */
+
+smtp_ungetc(rc);
+return TRUE;
+}
+
+
+/******************************************************************************/
+/*************************************************
+*          Recheck synchronization               *
+*************************************************/
+
+/* Synchronization checks can never be perfect because a packet may be on its
+way but not arrived when the check is done.  Normally, the checks happen when
+commands are read: Exim ensures that there is no more input in the input buffer.
+In normal cases, the response to the command will be fast, and there is no
+further check.
+
+However, for some commands an ACL is run, and that can include delays. In those
+cases, it is useful to do another check on the input just before sending the
+response. This also applies at the start of a connection. This function does
+that check by means of the select() function, as long as the facility is not
+disabled or inappropriate. A failure of select() is ignored.
+
+When there is unwanted input, we read it so that it appears in the log of the
+error.
+
+Arguments: none
+Returns:   TRUE if all is well; FALSE if there is input pending
+*/
+
+static BOOL
+wouldblock_reading(void)
+{
+#ifndef DISABLE_TLS
+if (tls_in.active.sock >= 0)
+ return !tls_could_getc();
+#endif
+
+return !smtp_could_getc();
+}
+
+static BOOL
+check_sync(void)
+{
+if (!smtp_enforce_sync || !sender_host_address || f.sender_host_notsocket)
+  return TRUE;
+
+return wouldblock_reading();
+}
+
+
+/******************************************************************************/
+/* Variants of the smtp_* input handling functions for use in CHUNKING mode */
+
+/* Forward declarations */
+static inline void bdat_push_receive_functions(void);
+static inline void bdat_pop_receive_functions(void);
+
+
+/* Get a byte from the smtp input, in CHUNKING mode.  Handle ack of the
+previous BDAT chunk and getting new ones when we run out.  Uses the
+underlying smtp_getc or tls_getc both for that and for getting the
+(buffered) data byte.  EOD signals (an expected) no further data.
+ERR signals a protocol error, and EOF a closed input stream.
+
+Called from read_bdat_smtp() in receive.c for the message body, but also
+by the headers read loop in receive_msg(); manipulates chunking_state
+to handle the BDAT command/response.
+Placed here due to the correlation with the above smtp_getc(), which it wraps,
+and also by the need to do smtp command/response handling.
+
+Arguments:  lim		(ignored)
+Returns:    the next character or ERR, EOD or EOF
+*/
+
+int
+bdat_getc(unsigned lim)
+{
+uschar * user_msg = NULL;
+uschar * log_msg;
+
+for(;;)
+  {
+#ifndef DISABLE_DKIM
+  unsigned dkim_save;
+#endif
+
+  if (chunking_data_left > 0)
+    return lwr_receive_getc(chunking_data_left--);
+
+  bdat_pop_receive_functions();
+#ifndef DISABLE_DKIM
+  dkim_save = dkim_collect_input;
+  dkim_collect_input = 0;
+#endif
+
+  /* Unless PIPELINING was offered, there should be no next command
+  until after we ack that chunk */
+
+  if (!f.smtp_in_pipelining_advertised && !check_sync())
+    {
+    unsigned n = smtp_inend - smtp_inptr;
+    if (n > 32) n = 32;
+
+    incomplete_transaction_log(US"sync failure");
+    log_write(0, LOG_MAIN|LOG_REJECT, "SMTP protocol synchronization error "
+      "(next input sent too soon: pipelining was not advertised): "
+      "rejected \"%s\" %s next input=\"%s\"%s",
+      smtp_cmd_buffer, host_and_ident(TRUE),
+      string_printing(string_copyn(smtp_inptr, n)),
+      smtp_inend - smtp_inptr > n ? "..." : "");
+    (void) synprot_error(L_smtp_protocol_error, 554, NULL,
+      US"SMTP synchronization error");
+    goto repeat_until_rset;
+    }
+
+  /* If not the last, ack the received chunk.  The last response is delayed
+  until after the data ACL decides on it */
+
+  if (chunking_state == CHUNKING_LAST)
+    {
+#ifndef DISABLE_DKIM
+    dkim_collect_input = dkim_save;
+    dkim_exim_verify_feed(NULL, 0);	/* notify EOD */
+    dkim_collect_input = 0;
+#endif
+    return EOD;
+    }
+
+  smtp_printf("250 %u byte chunk received\r\n", FALSE, chunking_datasize);
+  chunking_state = CHUNKING_OFFERED;
+  DEBUG(D_receive) debug_printf("chunking state %d\n", (int)chunking_state);
+
+  /* Expect another BDAT cmd from input. RFC 3030 says nothing about
+  QUIT, RSET or NOOP but handling them seems obvious */
+
+next_cmd:
+  switch(smtp_read_command(TRUE, 1))
+    {
+    default:
+      (void) synprot_error(L_smtp_protocol_error, 503, NULL,
+	US"only BDAT permissible after non-LAST BDAT");
+
+  repeat_until_rset:
+      switch(smtp_read_command(TRUE, 1))
+	{
+	case QUIT_CMD:	smtp_quit_handler(&user_msg, &log_msg);	/*FALLTHROUGH */
+	case EOF_CMD:	return EOF;
+	case RSET_CMD:	smtp_rset_handler(); return ERR;
+	default:	if (synprot_error(L_smtp_protocol_error, 503, NULL,
+					  US"only RSET accepted now") > 0)
+			  return EOF;
+			goto repeat_until_rset;
+	}
+
+    case QUIT_CMD:
+      smtp_quit_handler(&user_msg, &log_msg);
+      /*FALLTHROUGH*/
+    case EOF_CMD:
+      return EOF;
+
+    case RSET_CMD:
+      smtp_rset_handler();
+      return ERR;
+
+    case NOOP_CMD:
+      HAD(SCH_NOOP);
+      smtp_printf("250 OK\r\n", FALSE);
+      goto next_cmd;
+
+    case BDAT_CMD:
+      {
+      int n;
+
+      if (sscanf(CS smtp_cmd_data, "%u %n", &chunking_datasize, &n) < 1)
+	{
+	(void) synprot_error(L_smtp_protocol_error, 501, NULL,
+	  US"missing size for BDAT command");
+	return ERR;
+	}
+      chunking_state = strcmpic(smtp_cmd_data+n, US"LAST") == 0
+	? CHUNKING_LAST : CHUNKING_ACTIVE;
+      chunking_data_left = chunking_datasize;
+      DEBUG(D_receive) debug_printf("chunking state %d, %d bytes\n",
+				    (int)chunking_state, chunking_data_left);
+
+      if (chunking_datasize == 0)
+	if (chunking_state == CHUNKING_LAST)
+	  return EOD;
+	else
+	  {
+	  (void) synprot_error(L_smtp_protocol_error, 504, NULL,
+	    US"zero size for BDAT command");
+	  goto repeat_until_rset;
+	  }
+
+      bdat_push_receive_functions();
+#ifndef DISABLE_DKIM
+      dkim_collect_input = dkim_save;
+#endif
+      break;	/* to top of main loop */
+      }
+    }
+  }
+}
+
+BOOL
+bdat_hasc(void)
+{
+if (chunking_data_left > 0)
+  return lwr_receive_hasc();
+return TRUE;
+}
+
+uschar *
+bdat_getbuf(unsigned * len)
+{
+uschar * buf;
+
+if (chunking_data_left <= 0)
+  { *len = 0; return NULL; }
+
+if (*len > chunking_data_left) *len = chunking_data_left;
+buf = lwr_receive_getbuf(len);	/* Either smtp_getbuf or tls_getbuf */
+chunking_data_left -= *len;
+return buf;
+}
+
+void
+bdat_flush_data(void)
+{
+while (chunking_data_left)
+  {
+  unsigned n = chunking_data_left;
+  if (!bdat_getbuf(&n)) break;
+  }
+
+bdat_pop_receive_functions();
+chunking_state = CHUNKING_OFFERED;
+DEBUG(D_receive) debug_printf("chunking state %d\n", (int)chunking_state);
+}
+
+
+static inline void
+bdat_push_receive_functions(void)
+{
+/* push the current receive_* function on the "stack", and
+replace them by bdat_getc(), which in turn will use the lwr_receive_*
+functions to do the dirty work. */
+if (!lwr_receive_getc)
+  {
+  lwr_receive_getc = receive_getc;
+  lwr_receive_getbuf = receive_getbuf;
+  lwr_receive_hasc = receive_hasc;
+  lwr_receive_ungetc = receive_ungetc;
+  }
+else
+  {
+  DEBUG(D_receive) debug_printf("chunking double-push receive functions\n");
+  }
+
+receive_getc = bdat_getc;
+receive_getbuf = bdat_getbuf;
+receive_hasc = bdat_hasc;
+receive_ungetc = bdat_ungetc;
+}
+
+static inline void
+bdat_pop_receive_functions(void)
+{
+if (!lwr_receive_getc)
+  {
+  DEBUG(D_receive) debug_printf("chunking double-pop receive functions\n");
+  return;
+  }
+receive_getc = lwr_receive_getc;
+receive_getbuf = lwr_receive_getbuf;
+receive_hasc = lwr_receive_hasc;
+receive_ungetc = lwr_receive_ungetc;
+
+lwr_receive_getc = NULL;
+lwr_receive_getbuf = NULL;
+lwr_receive_hasc = NULL;
+lwr_receive_ungetc = NULL;
+}
+
+int
+bdat_ungetc(int ch)
+{
+chunking_data_left++;
+bdat_push_receive_functions();  /* we're not done yet, calling push is safe, because it checks the state before pushing anything */
+return lwr_receive_ungetc(ch);
+}
+
+
+
+/******************************************************************************/
+
+/*************************************************
+*     Write formatted string to SMTP channel     *
+*************************************************/
+
+/* This is a separate function so that we don't have to repeat everything for
+TLS support or debugging. It is global so that the daemon and the
+authentication functions can use it. It does not return any error indication,
+because major problems such as dropped connections won't show up till an output
+flush for non-TLS connections. The smtp_fflush() function is available for
+checking that: for convenience, TLS output errors are remembered here so that
+they are also picked up later by smtp_fflush().
+
+This function is exposed to the local_scan API; do not change the signature.
+
+Arguments:
+  format      format string
+  more	      further data expected
+  ...         optional arguments
+
+Returns:      nothing
+*/
+
+void
+smtp_printf(const char *format, BOOL more, ...)
+{
+va_list ap;
+
+va_start(ap, more);
+smtp_vprintf(format, more, ap);
+va_end(ap);
+}
+
+/* This is split off so that verify.c:respond_printf() can, in effect, call
+smtp_printf(), bearing in mind that in C a vararg function can't directly
+call another vararg function, only a function which accepts a va_list.
+
+This function is exposed to the local_scan API; do not change the signature.
+*/
+/*XXX consider passing caller-info in, for string_vformat-onward */
+
+void
+smtp_vprintf(const char *format, BOOL more, va_list ap)
+{
+gstring gs = { .size = big_buffer_size, .ptr = 0, .s = big_buffer };
+BOOL yield;
+
+/* Use taint-unchecked routines for writing into big_buffer, trusting
+that we'll never expand it. */
+
+yield = !! string_vformat(&gs, SVFMT_TAINT_NOCHK, format, ap);
+string_from_gstring(&gs);
+
+DEBUG(D_receive) for (const uschar * t, * s = gs.s;
+		      s && (t = Ustrchr(s, '\r'));
+		      s = t + 2)				/* \r\n */
+    debug_printf("%s %.*s\n",
+		  s == gs.s ? "SMTP>>" : "      ",
+		  (int)(t - s), s);
+
+if (!yield)
+  {
+  log_write(0, LOG_MAIN|LOG_PANIC, "string too large in smtp_printf()");
+  smtp_closedown(US"Unexpected error");
+  exim_exit(EXIT_FAILURE);
+  }
+
+/* If this is the first output for a (non-batch) RCPT command, see if all RCPTs
+have had the same. Note: this code is also present in smtp_respond(). It would
+be tidier to have it only in one place, but when it was added, it was easier to
+do it that way, so as not to have to mess with the code for the RCPT command,
+which sometimes uses smtp_printf() and sometimes smtp_respond(). */
+
+if (fl.rcpt_in_progress)
+  {
+  if (!rcpt_smtp_response)
+    rcpt_smtp_response = string_copy(big_buffer);
+  else if (fl.rcpt_smtp_response_same &&
+           Ustrcmp(rcpt_smtp_response, big_buffer) != 0)
+    fl.rcpt_smtp_response_same = FALSE;
+  fl.rcpt_in_progress = FALSE;
+  }
+
+/* Now write the string */
+
+if (
+#ifndef DISABLE_TLS
+    tls_in.active.sock >= 0 ? (tls_write(NULL, gs.s, gs.ptr, more) < 0) :
+#endif
+    (fwrite(gs.s, gs.ptr, 1, smtp_out) == 0)
+   )
+    smtp_write_error = -1;
+}
+
+
+
+/*************************************************
+*        Flush SMTP out and check for error      *
+*************************************************/
+
+/* This function isn't currently used within Exim (it detects errors when it
+tries to read the next SMTP input), but is available for use in local_scan().
+It flushes the output and checks for errors.
+
+Arguments:  none
+Returns:    0 for no error; -1 after an error
+*/
+
+int
+smtp_fflush(void)
+{
+if (tls_in.active.sock < 0 && fflush(smtp_out) != 0) smtp_write_error = -1;
+
+if (
+#ifndef DISABLE_TLS
+    tls_in.active.sock >= 0 ? (tls_write(NULL, NULL, 0, FALSE) < 0) :
+#endif
+    (fflush(smtp_out) != 0)
+   )
+    smtp_write_error = -1;
+
+return smtp_write_error;
+}
+
+
+
+/* If there's input waiting (and we're doing pipelineing) then we can pipeline
+a reponse with the one following. */
+
+static BOOL
+pipeline_response(void)
+{
+if (  !smtp_enforce_sync || !sender_host_address
+   || f.sender_host_notsocket || !f.smtp_in_pipelining_advertised)
+  return FALSE;
+
+if (wouldblock_reading()) return FALSE;
+f.smtp_in_pipelining_used = TRUE;
+return TRUE;
+}
+
+
+#ifndef DISABLE_PIPE_CONNECT
+static BOOL
+pipeline_connect_sends(void)
+{
+if (!sender_host_address || f.sender_host_notsocket || !fl.pipe_connect_acceptable)
+  return FALSE;
+
+if (wouldblock_reading()) return FALSE;
+f.smtp_in_early_pipe_used = TRUE;
+return TRUE;
+}
+#endif
+
+/*************************************************
+*          SMTP command read timeout             *
+*************************************************/
+
+/* Signal handler for timing out incoming SMTP commands. This attempts to
+finish off tidily.
+
+Argument: signal number (SIGALRM)
+Returns:  nothing
+*/
+
+static void
+command_timeout_handler(int sig)
+{
+had_command_timeout = sig;
+}
+
+
+
+/*************************************************
+*               SIGTERM received                 *
+*************************************************/
+
+/* Signal handler for handling SIGTERM. Again, try to finish tidily.
+
+Argument: signal number (SIGTERM)
+Returns:  nothing
+*/
+
+static void
+command_sigterm_handler(int sig)
+{
+had_command_sigterm = sig;
+}
+
+
+
+
+#ifdef SUPPORT_PROXY
+/*************************************************
+*       Check if host is required proxy host     *
+*************************************************/
+/* The function determines if inbound host will be a regular smtp host
+or if it is configured that it must use Proxy Protocol.  A local
+connection cannot.
+
+Arguments: none
+Returns:   bool
+*/
+
+static BOOL
+check_proxy_protocol_host()
+{
+int rc;
+
+if (  sender_host_address
+   && (rc = verify_check_this_host(CUSS &hosts_proxy, NULL, NULL,
+                           sender_host_address, NULL)) == OK)
+  {
+  DEBUG(D_receive)
+    debug_printf("Detected proxy protocol configured host\n");
+  proxy_session = TRUE;
+  }
+return proxy_session;
+}
+
+
+/*************************************************
+*    Read data until newline or end of buffer    *
+*************************************************/
+/* While SMTP is server-speaks-first, TLS is client-speaks-first, so we can't
+read an entire buffer and assume there will be nothing past a proxy protocol
+header.  Our approach normally is to use stdio, but again that relies upon
+"STARTTLS\r\n" and a server response before the client starts TLS handshake, or
+reading _nothing_ before client TLS handshake.  So we don't want to use the
+usual buffering reads which may read enough to block TLS starting.
+
+So unfortunately we're down to "read one byte at a time, with a syscall each,
+and expect a little overhead", for all proxy-opened connections which are v1,
+just to handle the TLS-on-connect case.  Since SSL functions wrap the
+underlying fd, we can't assume that we can feed them any already-read content.
+
+We need to know where to read to, the max capacity, and we'll read until we
+get a CR and one more character.  Let the caller scream if it's CR+!LF.
+
+Return the amount read.
+*/
+
+static int
+swallow_until_crlf(int fd, uschar *base, int already, int capacity)
+{
+uschar *to = base + already;
+uschar *cr;
+int have = 0;
+int ret;
+int last = 0;
+
+/* For "PROXY UNKNOWN\r\n" we, at time of writing, expect to have read
+up through the \r; for the _normal_ case, we haven't yet seen the \r. */
+
+cr = memchr(base, '\r', already);
+if (cr != NULL)
+  {
+  if ((cr - base) < already - 1)
+    {
+    /* \r and presumed \n already within what we have; probably not
+    actually proxy protocol, but abort cleanly. */
+    return 0;
+    }
+  /* \r is last character read, just need one more. */
+  last = 1;
+  }
+
+while (capacity > 0)
+  {
+  do { ret = read(fd, to, 1); } while (ret == -1 && errno == EINTR && !had_command_timeout);
+  if (ret == -1)
+    return -1;
+  have++;
+  if (last)
+    return have;
+  if (*to == '\r')
+    last = 1;
+  capacity--;
+  to++;
+  }
+
+/* reached end without having room for a final newline, abort */
+errno = EOVERFLOW;
+return -1;
+}
+
+/*************************************************
+*         Setup host for proxy protocol          *
+*************************************************/
+/* The function configures the connection based on a header from the
+inbound host to use Proxy Protocol. The specification is very exact
+so exit with an error if do not find the exact required pieces. This
+includes an incorrect number of spaces separating args.
+
+Arguments: none
+Returns:   Boolean success
+*/
+
+static void
+setup_proxy_protocol_host()
+{
+union {
+  struct {
+    uschar line[108];
+  } v1;
+  struct {
+    uschar sig[12];
+    uint8_t ver_cmd;
+    uint8_t fam;
+    uint16_t len;
+    union {
+      struct { /* TCP/UDP over IPv4, len = 12 */
+        uint32_t src_addr;
+        uint32_t dst_addr;
+        uint16_t src_port;
+        uint16_t dst_port;
+      } ip4;
+      struct { /* TCP/UDP over IPv6, len = 36 */
+        uint8_t  src_addr[16];
+        uint8_t  dst_addr[16];
+        uint16_t src_port;
+        uint16_t dst_port;
+      } ip6;
+      struct { /* AF_UNIX sockets, len = 216 */
+        uschar   src_addr[108];
+        uschar   dst_addr[108];
+      } unx;
+    } addr;
+  } v2;
+} hdr;
+
+/* Temp variables used in PPv2 address:port parsing */
+uint16_t tmpport;
+char tmpip[INET_ADDRSTRLEN];
+struct sockaddr_in tmpaddr;
+char tmpip6[INET6_ADDRSTRLEN];
+struct sockaddr_in6 tmpaddr6;
+
+/* We can't read "all data until end" because while SMTP is
+server-speaks-first, the TLS handshake is client-speaks-first, so for
+TLS-on-connect ports the proxy protocol header will usually be immediately
+followed by a TLS handshake, and with N TLS libraries, we can't reliably
+reinject data for reading by those.  So instead we first read "enough to be
+safely read within the header, and figure out how much more to read".
+For v1 we will later read to the end-of-line, for v2 we will read based upon
+the stated length.
+
+The v2 sig is 12 octets, and another 4 gets us the length, so we know how much
+data is needed total.  For v1, where the line looks like:
+PROXY TCPn L3src L3dest SrcPort DestPort \r\n
+
+However, for v1 there's also `PROXY UNKNOWN\r\n` which is only 15 octets.
+We seem to support that.  So, if we read 14 octets then we can tell if we're
+v2 or v1.  If we're v1, we can continue reading as normal.
+
+If we're v2, we can't slurp up the entire header.  We need the length in the
+15th & 16th octets, then to read everything after that.
+
+So to safely handle v1 and v2, with client-sent-first supported correctly,
+we have to do a minimum of 3 read calls, not 1.  Eww.
+*/
+
+#define PROXY_INITIAL_READ 14
+#define PROXY_V2_HEADER_SIZE 16
+#if PROXY_INITIAL_READ > PROXY_V2_HEADER_SIZE
+# error Code bug in sizes of data to read for proxy usage
+#endif
+
+int get_ok = 0;
+int size, ret;
+int fd = fileno(smtp_in);
+const char v2sig[12] = "\x0D\x0A\x0D\x0A\x00\x0D\x0A\x51\x55\x49\x54\x0A";
+uschar * iptype;  /* To display debug info */
+socklen_t vslen = sizeof(struct timeval);
+BOOL yield = FALSE;
+
+os_non_restarting_signal(SIGALRM, command_timeout_handler);
+ALARM(proxy_protocol_timeout);
+
+do
+  {
+  /* The inbound host was declared to be a Proxy Protocol host, so
+  don't do a PEEK into the data, actually slurp up enough to be
+  "safe". Can't take it all because TLS-on-connect clients follow
+  immediately with TLS handshake. */
+  ret = read(fd, &hdr, PROXY_INITIAL_READ);
+  }
+  while (ret == -1 && errno == EINTR && !had_command_timeout);
+
+if (ret == -1)
+  goto proxyfail;
+
+/* For v2, handle reading the length, and then the rest. */
+if ((ret == PROXY_INITIAL_READ) && (memcmp(&hdr.v2, v2sig, sizeof(v2sig)) == 0))
+  {
+  int retmore;
+  uint8_t ver;
+
+  /* First get the length fields. */
+  do
+    {
+    retmore = read(fd, (uschar*)&hdr + ret, PROXY_V2_HEADER_SIZE - PROXY_INITIAL_READ);
+    } while (retmore == -1 && errno == EINTR && !had_command_timeout);
+  if (retmore == -1)
+    goto proxyfail;
+  ret += retmore;
+
+  ver = (hdr.v2.ver_cmd & 0xf0) >> 4;
+
+  /* May 2014: haproxy combined the version and command into one byte to
+  allow two full bytes for the length field in order to proxy SSL
+  connections.  SSL Proxy is not supported in this version of Exim, but
+  must still separate values here. */
+
+  if (ver != 0x02)
+    {
+    DEBUG(D_receive) debug_printf("Invalid Proxy Protocol version: %d\n", ver);
+    goto proxyfail;
+    }
+
+  /* The v2 header will always be 16 bytes per the spec. */
+  size = 16 + ntohs(hdr.v2.len);
+  DEBUG(D_receive) debug_printf("Detected PROXYv2 header, size %d (limit %d)\n",
+      size, (int)sizeof(hdr));
+
+  /* We should now have 16 octets (PROXY_V2_HEADER_SIZE), and we know the total
+  amount that we need.  Double-check that the size is not unreasonable, then
+  get the rest. */
+  if (size > sizeof(hdr))
+    {
+    DEBUG(D_receive) debug_printf("PROXYv2 header size unreasonably large; security attack?\n");
+    goto proxyfail;
+    }
+
+  do
+    {
+    do
+      {
+      retmore = read(fd, (uschar*)&hdr + ret, size-ret);
+      } while (retmore == -1 && errno == EINTR && !had_command_timeout);
+    if (retmore == -1)
+      goto proxyfail;
+    ret += retmore;
+    DEBUG(D_receive) debug_printf("PROXYv2: have %d/%d required octets\n", ret, size);
+    } while (ret < size);
+
+  } /* end scope for getting rest of data for v2 */
+
+/* At this point: if PROXYv2, we've read the exact size required for all data;
+if PROXYv1 then we've read "less than required for any valid line" and should
+read the rest". */
+
+if (ret >= 16 && memcmp(&hdr.v2, v2sig, 12) == 0)
+  {
+  uint8_t cmd = (hdr.v2.ver_cmd & 0x0f);
+
+  switch (cmd)
+    {
+    case 0x01: /* PROXY command */
+      switch (hdr.v2.fam)
+        {
+        case 0x11:  /* TCPv4 address type */
+          iptype = US"IPv4";
+          tmpaddr.sin_addr.s_addr = hdr.v2.addr.ip4.src_addr;
+          inet_ntop(AF_INET, &tmpaddr.sin_addr, CS &tmpip, sizeof(tmpip));
+          if (!string_is_ip_address(US tmpip, NULL))
+            {
+            DEBUG(D_receive) debug_printf("Invalid %s source IP\n", iptype);
+            goto proxyfail;
+            }
+          proxy_local_address = sender_host_address;
+          sender_host_address = string_copy(US tmpip);
+          tmpport             = ntohs(hdr.v2.addr.ip4.src_port);
+          proxy_local_port    = sender_host_port;
+          sender_host_port    = tmpport;
+          /* Save dest ip/port */
+          tmpaddr.sin_addr.s_addr = hdr.v2.addr.ip4.dst_addr;
+          inet_ntop(AF_INET, &tmpaddr.sin_addr, CS &tmpip, sizeof(tmpip));
+          if (!string_is_ip_address(US tmpip, NULL))
+            {
+            DEBUG(D_receive) debug_printf("Invalid %s dest port\n", iptype);
+            goto proxyfail;
+            }
+          proxy_external_address = string_copy(US tmpip);
+          tmpport              = ntohs(hdr.v2.addr.ip4.dst_port);
+          proxy_external_port  = tmpport;
+          goto done;
+        case 0x21:  /* TCPv6 address type */
+          iptype = US"IPv6";
+          memmove(tmpaddr6.sin6_addr.s6_addr, hdr.v2.addr.ip6.src_addr, 16);
+          inet_ntop(AF_INET6, &tmpaddr6.sin6_addr, CS &tmpip6, sizeof(tmpip6));
+          if (!string_is_ip_address(US tmpip6, NULL))
+            {
+            DEBUG(D_receive) debug_printf("Invalid %s source IP\n", iptype);
+            goto proxyfail;
+            }
+          proxy_local_address = sender_host_address;
+          sender_host_address = string_copy(US tmpip6);
+          tmpport             = ntohs(hdr.v2.addr.ip6.src_port);
+          proxy_local_port    = sender_host_port;
+          sender_host_port    = tmpport;
+          /* Save dest ip/port */
+          memmove(tmpaddr6.sin6_addr.s6_addr, hdr.v2.addr.ip6.dst_addr, 16);
+          inet_ntop(AF_INET6, &tmpaddr6.sin6_addr, CS &tmpip6, sizeof(tmpip6));
+          if (!string_is_ip_address(US tmpip6, NULL))
+            {
+            DEBUG(D_receive) debug_printf("Invalid %s dest port\n", iptype);
+            goto proxyfail;
+            }
+          proxy_external_address = string_copy(US tmpip6);
+          tmpport              = ntohs(hdr.v2.addr.ip6.dst_port);
+          proxy_external_port  = tmpport;
+          goto done;
+        default:
+          DEBUG(D_receive)
+            debug_printf("Unsupported PROXYv2 connection type: 0x%02x\n",
+                         hdr.v2.fam);
+          goto proxyfail;
+        }
+      /* Unsupported protocol, keep local connection address */
+      break;
+    case 0x00: /* LOCAL command */
+      /* Keep local connection address for LOCAL */
+      iptype = US"local";
+      break;
+    default:
+      DEBUG(D_receive)
+        debug_printf("Unsupported PROXYv2 command: 0x%x\n", cmd);
+      goto proxyfail;
+    }
+  }
+else if (ret >= 8 && memcmp(hdr.v1.line, "PROXY", 5) == 0)
+  {
+  uschar *p;
+  uschar *end;
+  uschar *sp;     /* Utility variables follow */
+  int     tmp_port;
+  int     r2;
+  char   *endc;
+
+  /* get the rest of the line */
+  r2 = swallow_until_crlf(fd, (uschar*)&hdr, ret, sizeof(hdr)-ret);
+  if (r2 == -1)
+    goto proxyfail;
+  ret += r2;
+
+  p = string_copy(hdr.v1.line);
+  end = memchr(p, '\r', ret - 1);
+
+  if (!end || (end == (uschar*)&hdr + ret) || end[1] != '\n')
+    {
+    DEBUG(D_receive) debug_printf("Partial or invalid PROXY header\n");
+    goto proxyfail;
+    }
+  *end = '\0'; /* Terminate the string */
+  size = end + 2 - p; /* Skip header + CRLF */
+  DEBUG(D_receive) debug_printf("Detected PROXYv1 header\n");
+  DEBUG(D_receive) debug_printf("Bytes read not within PROXY header: %d\n", ret - size);
+  /* Step through the string looking for the required fields. Ensure
+  strict adherence to required formatting, exit for any error. */
+  p += 5;
+  if (!isspace(*(p++)))
+    {
+    DEBUG(D_receive) debug_printf("Missing space after PROXY command\n");
+    goto proxyfail;
+    }
+  if (!Ustrncmp(p, CCS"TCP4", 4))
+    iptype = US"IPv4";
+  else if (!Ustrncmp(p,CCS"TCP6", 4))
+    iptype = US"IPv6";
+  else if (!Ustrncmp(p,CCS"UNKNOWN", 7))
+    {
+    iptype = US"Unknown";
+    goto done;
+    }
+  else
+    {
+    DEBUG(D_receive) debug_printf("Invalid TCP type\n");
+    goto proxyfail;
+    }
+
+  p += Ustrlen(iptype);
+  if (!isspace(*(p++)))
+    {
+    DEBUG(D_receive) debug_printf("Missing space after TCP4/6 command\n");
+    goto proxyfail;
+    }
+  /* Find the end of the arg */
+  if ((sp = Ustrchr(p, ' ')) == NULL)
+    {
+    DEBUG(D_receive)
+      debug_printf("Did not find proxied src %s\n", iptype);
+    goto proxyfail;
+    }
+  *sp = '\0';
+  if(!string_is_ip_address(p, NULL))
+    {
+    DEBUG(D_receive)
+      debug_printf("Proxied src arg is not an %s address\n", iptype);
+    goto proxyfail;
+    }
+  proxy_local_address = sender_host_address;
+  sender_host_address = p;
+  p = sp + 1;
+  if ((sp = Ustrchr(p, ' ')) == NULL)
+    {
+    DEBUG(D_receive)
+      debug_printf("Did not find proxy dest %s\n", iptype);
+    goto proxyfail;
+    }
+  *sp = '\0';
+  if(!string_is_ip_address(p, NULL))
+    {
+    DEBUG(D_receive)
+      debug_printf("Proxy dest arg is not an %s address\n", iptype);
+    goto proxyfail;
+    }
+  proxy_external_address = p;
+  p = sp + 1;
+  if ((sp = Ustrchr(p, ' ')) == NULL)
+    {
+    DEBUG(D_receive) debug_printf("Did not find proxied src port\n");
+    goto proxyfail;
+    }
+  *sp = '\0';
+  tmp_port = strtol(CCS p, &endc, 10);
+  if (*endc || tmp_port == 0)
+    {
+    DEBUG(D_receive)
+      debug_printf("Proxied src port '%s' not an integer\n", p);
+    goto proxyfail;
+    }
+  proxy_local_port = sender_host_port;
+  sender_host_port = tmp_port;
+  p = sp + 1;
+  if ((sp = Ustrchr(p, '\0')) == NULL)
+    {
+    DEBUG(D_receive) debug_printf("Did not find proxy dest port\n");
+    goto proxyfail;
+    }
+  tmp_port = strtol(CCS p, &endc, 10);
+  if (*endc || tmp_port == 0)
+    {
+    DEBUG(D_receive)
+      debug_printf("Proxy dest port '%s' not an integer\n", p);
+    goto proxyfail;
+    }
+  proxy_external_port = tmp_port;
+  /* Already checked for /r /n above. Good V1 header received. */
+  }
+else
+  {
+  /* Wrong protocol */
+  DEBUG(D_receive) debug_printf("Invalid proxy protocol version negotiation\n");
+  (void) swallow_until_crlf(fd, (uschar*)&hdr, ret, sizeof(hdr)-ret);
+  goto proxyfail;
+  }
+
+done:
+  DEBUG(D_receive)
+    debug_printf("Valid %s sender from Proxy Protocol header\n", iptype);
+  yield = proxy_session;
+
+/* Don't flush any potential buffer contents. Any input on proxyfail
+should cause a synchronization failure */
+
+proxyfail:
+  DEBUG(D_receive) if (had_command_timeout)
+    debug_printf("Timeout while reading proxy header\n");
+
+bad:
+  if (yield)
+    {
+    sender_host_name = NULL;
+    (void) host_name_lookup();
+    host_build_sender_fullhost();
+    }
+  else
+    {
+    f.proxy_session_failed = TRUE;
+    DEBUG(D_receive)
+      debug_printf("Failure to extract proxied host, only QUIT allowed\n");
+    }
+
+ALARM(0);
+return;
+}
+#endif
+
+/*************************************************
+*           Read one command line                *
+*************************************************/
+
+/* Strictly, SMTP commands coming over the net are supposed to end with CRLF.
+There are sites that don't do this, and in any case internal SMTP probably
+should check only for LF. Consequently, we check here for LF only. The line
+ends up with [CR]LF removed from its end. If we get an overlong line, treat as
+an unknown command. The command is read into the global smtp_cmd_buffer so that
+it is available via $smtp_command.
+
+The character reading routine sets up a timeout for each block actually read
+from the input (which may contain more than one command). We set up a special
+signal handler that closes down the session on a timeout. Control does not
+return when it runs.
+
+Arguments:
+  check_sync	if TRUE, check synchronization rules if global option is TRUE
+  buffer_lim	maximum to buffer in lower layer
+
+Returns:       a code identifying the command (enumerated above)
+*/
+
+static int
+smtp_read_command(BOOL check_sync, unsigned buffer_lim)
+{
+int c;
+int ptr = 0;
+BOOL hadnull = FALSE;
+
+had_command_timeout = 0;
+os_non_restarting_signal(SIGALRM, command_timeout_handler);
+
+while ((c = (receive_getc)(buffer_lim)) != '\n' && c != EOF)
+  {
+  if (ptr >= SMTP_CMD_BUFFER_SIZE)
+    {
+    os_non_restarting_signal(SIGALRM, sigalrm_handler);
+    return OTHER_CMD;
+    }
+  if (c == 0)
+    {
+    hadnull = TRUE;
+    c = '?';
+    }
+  smtp_cmd_buffer[ptr++] = c;
+  }
+
+receive_linecount++;    /* For BSMTP errors */
+os_non_restarting_signal(SIGALRM, sigalrm_handler);
+
+/* If hit end of file, return pseudo EOF command. Whether we have a
+part-line already read doesn't matter, since this is an error state. */
+
+if (c == EOF) return EOF_CMD;
+
+/* Remove any CR and white space at the end of the line, and terminate the
+string. */
+
+while (ptr > 0 && isspace(smtp_cmd_buffer[ptr-1])) ptr--;
+smtp_cmd_buffer[ptr] = 0;
+
+DEBUG(D_receive) debug_printf("SMTP<< %s\n", smtp_cmd_buffer);
+
+/* NULLs are not allowed in SMTP commands */
+
+if (hadnull) return BADCHAR_CMD;
+
+/* Scan command list and return identity, having set the data pointer
+to the start of the actual data characters. Check for SMTP synchronization
+if required. */
+
+for (smtp_cmd_list * p = cmd_list; p < cmd_list_end; p++)
+  {
+#ifdef SUPPORT_PROXY
+  /* Only allow QUIT command if Proxy Protocol parsing failed */
+  if (proxy_session && f.proxy_session_failed && p->cmd != QUIT_CMD)
+    continue;
+#endif
+  if (  p->len
+     && strncmpic(smtp_cmd_buffer, US p->name, p->len) == 0
+     && (  smtp_cmd_buffer[p->len-1] == ':'    /* "mail from:" or "rcpt to:" */
+        || smtp_cmd_buffer[p->len] == 0
+	|| smtp_cmd_buffer[p->len] == ' '
+     )  )
+    {
+    if (   smtp_inptr < smtp_inend		/* Outstanding input */
+       &&  p->cmd < sync_cmd_limit		/* Command should sync */
+       &&  check_sync				/* Local flag set */
+       &&  smtp_enforce_sync			/* Global flag set */
+       &&  sender_host_address != NULL		/* Not local input */
+       &&  !f.sender_host_notsocket		/* Really is a socket */
+       )
+      return BADSYN_CMD;
+
+    /* The variables $smtp_command and $smtp_command_argument point into the
+    unmodified input buffer. A copy of the latter is taken for actual
+    processing, so that it can be chopped up into separate parts if necessary,
+    for example, when processing a MAIL command options such as SIZE that can
+    follow the sender address. */
+
+    smtp_cmd_argument = smtp_cmd_buffer + p->len;
+    while (isspace(*smtp_cmd_argument)) smtp_cmd_argument++;
+    Ustrcpy(smtp_data_buffer, smtp_cmd_argument);
+    smtp_cmd_data = smtp_data_buffer;
+
+    /* Count non-mail commands from those hosts that are controlled in this
+    way. The default is all hosts. We don't waste effort checking the list
+    until we get a non-mail command, but then cache the result to save checking
+    again. If there's a DEFER while checking the host, assume it's in the list.
+
+    Note that one instance of RSET, EHLO/HELO, and STARTTLS is allowed at the
+    start of each incoming message by fiddling with the value in the table. */
+
+    if (!p->is_mail_cmd)
+      {
+      if (count_nonmail == TRUE_UNSET) count_nonmail =
+        verify_check_host(&smtp_accept_max_nonmail_hosts) != FAIL;
+      if (count_nonmail && ++nonmail_command_count > smtp_accept_max_nonmail)
+        return TOO_MANY_NONMAIL_CMD;
+      }
+
+    /* If there is data for a command that does not expect it, generate the
+    error here. */
+
+    return (p->has_arg || *smtp_cmd_data == 0)? p->cmd : BADARG_CMD;
+    }
+  }
+
+#ifdef SUPPORT_PROXY
+/* Only allow QUIT command if Proxy Protocol parsing failed */
+if (proxy_session && f.proxy_session_failed)
+  return PROXY_FAIL_IGNORE_CMD;
+#endif
+
+/* Enforce synchronization for unknown commands */
+
+if (  smtp_inptr < smtp_inend		/* Outstanding input */
+   && check_sync			/* Local flag set */
+   && smtp_enforce_sync			/* Global flag set */
+   && sender_host_address		/* Not local input */
+   && !f.sender_host_notsocket		/* Really is a socket */
+   )
+  return BADSYN_CMD;
+
+return OTHER_CMD;
+}
+
+
+
+/*************************************************
+*          Forced closedown of call              *
+*************************************************/
+
+/* This function is called from log.c when Exim is dying because of a serious
+disaster, and also from some other places. If an incoming non-batched SMTP
+channel is open, it swallows the rest of the incoming message if in the DATA
+phase, sends the reply string, and gives an error to all subsequent commands
+except QUIT. The existence of an SMTP call is detected by the non-NULLness of
+smtp_in.
+
+Arguments:
+  message   SMTP reply string to send, excluding the code
+
+Returns:    nothing
+*/
+
+void
+smtp_closedown(uschar * message)
+{
+if (!smtp_in || smtp_batched_input) return;
+receive_swallow_smtp();
+smtp_printf("421 %s\r\n", FALSE, message);
+
+for (;;) switch(smtp_read_command(FALSE, GETC_BUFFER_UNLIMITED))
+  {
+  case EOF_CMD:
+    return;
+
+  case QUIT_CMD:
+    f.smtp_in_quit = TRUE;
+    smtp_printf("221 %s closing connection\r\n", FALSE, smtp_active_hostname);
+    mac_smtp_fflush();
+    return;
+
+  case RSET_CMD:
+    smtp_printf("250 Reset OK\r\n", FALSE);
+    break;
+
+  default:
+    smtp_printf("421 %s\r\n", FALSE, message);
+    break;
+  }
+}
+
+
+
+
+/*************************************************
+*        Set up connection info for logging      *
+*************************************************/
+
+/* This function is called when logging information about an SMTP connection.
+It sets up appropriate source information, depending on the type of connection.
+If sender_fullhost is NULL, we are at a very early stage of the connection;
+just use the IP address.
+
+Argument:    none
+Returns:     a string describing the connection
+*/
+
+uschar *
+smtp_get_connection_info(void)
+{
+const uschar * hostname = sender_fullhost
+  ? sender_fullhost : sender_host_address;
+
+if (host_checking)
+  return string_sprintf("SMTP connection from %s", hostname);
+
+if (f.sender_host_unknown || f.sender_host_notsocket)
+  return string_sprintf("SMTP connection from %s", sender_ident);
+
+if (f.is_inetd)
+  return string_sprintf("SMTP connection from %s (via inetd)", hostname);
+
+if (LOGGING(incoming_interface) && interface_address)
+  return string_sprintf("SMTP connection from %s I=[%s]:%d", hostname,
+    interface_address, interface_port);
+
+return string_sprintf("SMTP connection from %s", hostname);
+}
+
+
+
+#ifndef DISABLE_TLS
+/* Append TLS-related information to a log line
+
+Arguments:
+  g		String under construction: allocated string to extend, or NULL
+
+Returns:	Allocated string or NULL
+*/
+static gstring *
+s_tlslog(gstring * g)
+{
+if (LOGGING(tls_cipher) && tls_in.cipher)
+  {
+  g = string_append(g, 2, US" X=", tls_in.cipher);
+#ifndef DISABLE_TLS_RESUME
+  if (LOGGING(tls_resumption) && tls_in.resumption & RESUME_USED)
+    g = string_catn(g, US"*", 1);
+#endif
+  }
+if (LOGGING(tls_certificate_verified) && tls_in.cipher)
+  g = string_append(g, 2, US" CV=", tls_in.certificate_verified? "yes":"no");
+if (LOGGING(tls_peerdn) && tls_in.peerdn)
+  g = string_append(g, 3, US" DN=\"", string_printing(tls_in.peerdn), US"\"");
+if (LOGGING(tls_sni) && tls_in.sni)
+  g = string_append(g, 2, US" SNI=", string_printing2(tls_in.sni, SP_TAB|SP_SPACE));
+return g;
+}
+#endif
+
+
+
+static gstring *
+s_connhad_log(gstring * g)
+{
+const uschar * sep = smtp_connection_had[SMTP_HBUFF_SIZE-1] != SCH_NONE
+  ? US" C=..." : US" C=";
+
+for (int i = smtp_ch_index; i < SMTP_HBUFF_SIZE; i++)
+  if (smtp_connection_had[i] != SCH_NONE)
+    {
+    g = string_append(g, 2, sep, smtp_names[smtp_connection_had[i]]);
+    sep = US",";
+    }
+for (int i = 0; i < smtp_ch_index; i++, sep = US",")
+  g = string_append(g, 2, sep, smtp_names[smtp_connection_had[i]]);
+return g;
+}
+
+
+/*************************************************
+*      Log lack of MAIL if so configured         *
+*************************************************/
+
+/* This function is called when an SMTP session ends. If the log selector
+smtp_no_mail is set, write a log line giving some details of what has happened
+in the SMTP session.
+
+Arguments:   none
+Returns:     nothing
+*/
+
+void
+smtp_log_no_mail(void)
+{
+uschar * s;
+gstring * g = NULL;
+
+if (smtp_mailcmd_count > 0 || !LOGGING(smtp_no_mail))
+  return;
+
+if (sender_host_authenticated)
+  {
+  g = string_append(g, 2, US" A=", sender_host_authenticated);
+  if (authenticated_id) g = string_append(g, 2, US":", authenticated_id);
+  }
+
+#ifndef DISABLE_TLS
+g = s_tlslog(g);
+#endif
+
+g = s_connhad_log(g);
+
+if (!(s = string_from_gstring(g))) s = US"";
+
+log_write(0, LOG_MAIN, "no MAIL in %sSMTP connection from %s D=%s%s",
+  f.tcp_in_fastopen ? f.tcp_in_fastopen_data ? US"TFO* " : US"TFO " : US"",
+  host_and_ident(FALSE), string_timesince(&smtp_connection_start), s);
+}
+
+
+/* Return list of recent smtp commands */
+
+uschar *
+smtp_cmd_hist(void)
+{
+gstring * list = NULL;
+uschar * s;
+
+for (int i = smtp_ch_index; i < SMTP_HBUFF_SIZE; i++)
+  if (smtp_connection_had[i] != SCH_NONE)
+    list = string_append_listele(list, ',', smtp_names[smtp_connection_had[i]]);
+
+for (int i = 0; i < smtp_ch_index; i++)
+  list = string_append_listele(list, ',', smtp_names[smtp_connection_had[i]]);
+
+s = string_from_gstring(list);
+return s ? s : US"";
+}
+
+
+
+
+/*************************************************
+*   Check HELO line and set sender_helo_name     *
+*************************************************/
+
+/* Check the format of a HELO line. The data for HELO/EHLO is supposed to be
+the domain name of the sending host, or an ip literal in square brackets. The
+argument is placed in sender_helo_name, which is in malloc store, because it
+must persist over multiple incoming messages. If helo_accept_junk is set, this
+host is permitted to send any old junk (needed for some broken hosts).
+Otherwise, helo_allow_chars can be used for rogue characters in general
+(typically people want to let in underscores).
+
+Argument:
+  s       the data portion of the line (already past any white space)
+
+Returns:  TRUE or FALSE
+*/
+
+static BOOL
+check_helo(uschar *s)
+{
+uschar *start = s;
+uschar *end = s + Ustrlen(s);
+BOOL yield = fl.helo_accept_junk;
+
+/* Discard any previous helo name */
+
+sender_helo_name = NULL;
+
+/* Skip tests if junk is permitted. */
+
+if (!yield)
+
+  /* Allow the new standard form for IPv6 address literals, namely,
+  [IPv6:....], and because someone is bound to use it, allow an equivalent
+  IPv4 form. Allow plain addresses as well. */
+
+  if (*s == '[')
+    {
+    if (end[-1] == ']')
+      {
+      end[-1] = 0;
+      if (strncmpic(s, US"[IPv6:", 6) == 0)
+        yield = (string_is_ip_address(s+6, NULL) == 6);
+      else if (strncmpic(s, US"[IPv4:", 6) == 0)
+        yield = (string_is_ip_address(s+6, NULL) == 4);
+      else
+        yield = (string_is_ip_address(s+1, NULL) != 0);
+      end[-1] = ']';
+      }
+    }
+
+  /* Non-literals must be alpha, dot, hyphen, plus any non-valid chars
+  that have been configured (usually underscore - sigh). */
+
+  else if (*s)
+    for (yield = TRUE; *s; s++)
+      if (!isalnum(*s) && *s != '.' && *s != '-' &&
+          Ustrchr(helo_allow_chars, *s) == NULL)
+        {
+        yield = FALSE;
+        break;
+        }
+
+/* Save argument if OK */
+
+if (yield) sender_helo_name = string_copy_perm(start, TRUE);
+return yield;
+}
+
+
+
+
+
+/*************************************************
+*         Extract SMTP command option            *
+*************************************************/
+
+/* This function picks the next option setting off the end of smtp_cmd_data. It
+is called for MAIL FROM and RCPT TO commands, to pick off the optional ESMTP
+things that can appear there.
+
+Arguments:
+   name           point this at the name
+   value          point this at the data string
+
+Returns:          TRUE if found an option
+*/
+
+static BOOL
+extract_option(uschar **name, uschar **value)
+{
+uschar *n;
+uschar *v;
+if (Ustrlen(smtp_cmd_data) <= 0) return FALSE;
+v = smtp_cmd_data + Ustrlen(smtp_cmd_data) - 1;
+while (v > smtp_cmd_data && isspace(*v)) v--;
+v[1] = 0;
+
+while (v > smtp_cmd_data && *v != '=' && !isspace(*v))
+  {
+  /* Take care to not stop at a space embedded in a quoted local-part */
+  if (*v == '"')
+    {
+    do v--; while (v > smtp_cmd_data && *v != '"');
+    if (v <= smtp_cmd_data) return FALSE;
+    }
+  v--;
+  }
+if (v <= smtp_cmd_data) return FALSE;
+
+n = v;
+if (*v == '=')
+  {
+  while (n > smtp_cmd_data && isalpha(n[-1])) n--;
+  /* RFC says SP, but TAB seen in wild and other major MTAs accept it */
+  if (n <= smtp_cmd_data || !isspace(n[-1])) return FALSE;
+  n[-1] = 0;
+  }
+else
+  {
+  n++;
+  }
+*v++ = 0;
+*name = n;
+*value = v;
+return TRUE;
+}
+
+
+
+
+
+/*************************************************
+*         Reset for new message                  *
+*************************************************/
+
+/* This function is called whenever the SMTP session is reset from
+within either of the setup functions; also from the daemon loop.
+
+Argument:   the stacking pool storage reset point
+Returns:    nothing
+*/
+
+void *
+smtp_reset(void *reset_point)
+{
+recipients_list = NULL;
+rcpt_count = rcpt_defer_count = rcpt_fail_count =
+  raw_recipients_count = recipients_count = recipients_list_max = 0;
+message_linecount = 0;
+message_size = -1;
+message_body = message_body_end = NULL;
+acl_added_headers = NULL;
+acl_removed_headers = NULL;
+f.queue_only_policy = FALSE;
+rcpt_smtp_response = NULL;
+fl.rcpt_smtp_response_same = TRUE;
+fl.rcpt_in_progress = FALSE;
+f.deliver_freeze = FALSE;				/* Can be set by ACL */
+freeze_tell = freeze_tell_config;			/* Can be set by ACL */
+fake_response = OK;					/* Can be set by ACL */
+#ifdef WITH_CONTENT_SCAN
+f.no_mbox_unspool = FALSE;				/* Can be set by ACL */
+#endif
+f.submission_mode = FALSE;				/* Can be set by ACL */
+f.suppress_local_fixups = f.suppress_local_fixups_default; /* Can be set by ACL */
+f.active_local_from_check = local_from_check;		/* Can be set by ACL */
+f.active_local_sender_retain = local_sender_retain;	/* Can be set by ACL */
+sending_ip_address = NULL;
+return_path = sender_address = NULL;
+deliver_localpart_data = deliver_domain_data =
+recipient_data = sender_data = NULL;			/* Can be set by ACL */
+recipient_verify_failure = NULL;
+deliver_localpart_parent = deliver_localpart_orig = NULL;
+deliver_domain_parent = deliver_domain_orig = NULL;
+callout_address = NULL;
+submission_name = NULL;					/* Can be set by ACL */
+raw_sender = NULL;                  /* After SMTP rewrite, before qualifying */
+sender_address_unrewritten = NULL;  /* Set only after verify rewrite */
+sender_verified_list = NULL;        /* No senders verified */
+memset(sender_address_cache, 0, sizeof(sender_address_cache));
+memset(sender_domain_cache, 0, sizeof(sender_domain_cache));
+
+authenticated_sender = NULL;
+#ifdef EXPERIMENTAL_BRIGHTMAIL
+bmi_run = 0;
+bmi_verdicts = NULL;
+#endif
+dnslist_domain = dnslist_matched = NULL;
+#ifdef SUPPORT_SPF
+spf_header_comment = spf_received = spf_result = spf_smtp_comment = NULL;
+spf_result_guessed = FALSE;
+#endif
+#ifndef DISABLE_DKIM
+dkim_cur_signer = dkim_signers =
+dkim_signing_domain = dkim_signing_selector = dkim_signatures = NULL;
+dkim_cur_signer = dkim_signers = dkim_signing_domain = dkim_signing_selector = NULL;
+f.dkim_disable_verify = FALSE;
+dkim_collect_input = 0;
+dkim_verify_overall = dkim_verify_status = dkim_verify_reason = NULL;
+dkim_key_length = 0;
+#endif
+#ifdef SUPPORT_DMARC
+f.dmarc_has_been_checked = f.dmarc_disable_verify = f.dmarc_enable_forensic = FALSE;
+dmarc_domain_policy = dmarc_status = dmarc_status_text =
+dmarc_used_domain = NULL;
+#endif
+#ifdef EXPERIMENTAL_ARC
+arc_state = arc_state_reason = NULL;
+arc_received_instance = 0;
+#endif
+dsn_ret = 0;
+dsn_envid = NULL;
+deliver_host = deliver_host_address = NULL;	/* Can be set by ACL */
+#ifndef DISABLE_PRDR
+prdr_requested = FALSE;
+#endif
+#ifdef SUPPORT_I18N
+message_smtputf8 = FALSE;
+#endif
+body_linecount = body_zerocount = 0;
+
+sender_rate = sender_rate_limit = sender_rate_period = NULL;
+ratelimiters_mail = NULL;           /* Updated by ratelimit ACL condition */
+                   /* Note that ratelimiters_conn persists across resets. */
+
+/* Reset message ACL variables */
+
+acl_var_m = NULL;
+
+/* Warning log messages are saved in malloc store. They are saved to avoid
+repetition in the same message, but it seems right to repeat them for different
+messages. */
+
+while (acl_warn_logged)
+  {
+  string_item *this = acl_warn_logged;
+  acl_warn_logged = acl_warn_logged->next;
+  store_free(this);
+  }
+
+message_tidyup();
+store_reset(reset_point);
+
+message_start();
+return store_mark();
+}
+
+
+
+
+
+/*************************************************
+*  Initialize for incoming batched SMTP message  *
+*************************************************/
+
+/* This function is called from smtp_setup_msg() in the case when
+smtp_batched_input is true. This happens when -bS is used to pass a whole batch
+of messages in one file with SMTP commands between them. All errors must be
+reported by sending a message, and only MAIL FROM, RCPT TO, and DATA are
+relevant. After an error on a sender, or an invalid recipient, the remainder
+of the message is skipped. The value of received_protocol is already set.
+
+Argument: none
+Returns:  > 0 message successfully started (reached DATA)
+          = 0 QUIT read or end of file reached
+          < 0 should not occur
+*/
+
+static int
+smtp_setup_batch_msg(void)
+{
+int done = 0;
+rmark reset_point = store_mark();
+
+/* Save the line count at the start of each transaction - single commands
+like HELO and RSET count as whole transactions. */
+
+bsmtp_transaction_linecount = receive_linecount;
+
+if ((receive_feof)()) return 0;   /* Treat EOF as QUIT */
+
+cancel_cutthrough_connection(TRUE, US"smtp_setup_batch_msg");
+reset_point = smtp_reset(reset_point);                /* Reset for start of message */
+
+/* Deal with SMTP commands. This loop is exited by setting done to a POSITIVE
+value. The values are 2 larger than the required yield of the function. */
+
+while (done <= 0)
+  {
+  uschar *errmess;
+  uschar *recipient = NULL;
+  int start, end, sender_domain, recipient_domain;
+
+  switch(smtp_read_command(FALSE, GETC_BUFFER_UNLIMITED))
+    {
+    /* The HELO/EHLO commands set sender_address_helo if they have
+    valid data; otherwise they are ignored, except that they do
+    a reset of the state. */
+
+    case HELO_CMD:
+    case EHLO_CMD:
+
+      check_helo(smtp_cmd_data);
+      /* Fall through */
+
+    case RSET_CMD:
+      cancel_cutthrough_connection(TRUE, US"RSET received");
+      reset_point = smtp_reset(reset_point);
+      bsmtp_transaction_linecount = receive_linecount;
+      break;
+
+
+    /* The MAIL FROM command requires an address as an operand. All we
+    do here is to parse it for syntactic correctness. The form "<>" is
+    a special case which converts into an empty string. The start/end
+    pointers in the original are not used further for this address, as
+    it is the canonical extracted address which is all that is kept. */
+
+    case MAIL_CMD:
+      smtp_mailcmd_count++;              /* Count for no-mail log */
+      if (sender_address)
+	/* The function moan_smtp_batch() does not return. */
+	moan_smtp_batch(smtp_cmd_buffer, "503 Sender already given");
+
+      if (smtp_cmd_data[0] == 0)
+	/* The function moan_smtp_batch() does not return. */
+	moan_smtp_batch(smtp_cmd_buffer, "501 MAIL FROM must have an address operand");
+
+      /* Reset to start of message */
+
+      cancel_cutthrough_connection(TRUE, US"MAIL received");
+      reset_point = smtp_reset(reset_point);
+
+      /* Apply SMTP rewrite */
+
+      raw_sender = rewrite_existflags & rewrite_smtp
+	/* deconst ok as smtp_cmd_data was not const */
+        ? US rewrite_one(smtp_cmd_data, rewrite_smtp|rewrite_smtp_sender, NULL,
+		      FALSE, US"", global_rewrite_rules)
+	: smtp_cmd_data;
+
+      /* Extract the address; the TRUE flag allows <> as valid */
+
+      raw_sender =
+	parse_extract_address(raw_sender, &errmess, &start, &end, &sender_domain,
+	  TRUE);
+
+      if (!raw_sender)
+	/* The function moan_smtp_batch() does not return. */
+	moan_smtp_batch(smtp_cmd_buffer, "501 %s", errmess);
+
+      sender_address = string_copy(raw_sender);
+
+      /* Qualify unqualified sender addresses if permitted to do so. */
+
+      if (  !sender_domain
+         && sender_address[0] != 0 && sender_address[0] != '@')
+	if (f.allow_unqualified_sender)
+	  {
+	  /* deconst ok as sender_address was not const */
+	  sender_address = US rewrite_address_qualify(sender_address, FALSE);
+	  DEBUG(D_receive) debug_printf("unqualified address %s accepted "
+	    "and rewritten\n", raw_sender);
+	  }
+	/* The function moan_smtp_batch() does not return. */
+	else
+	  moan_smtp_batch(smtp_cmd_buffer, "501 sender address must contain "
+	    "a domain");
+      break;
+
+
+    /* The RCPT TO command requires an address as an operand. All we do
+    here is to parse it for syntactic correctness. There may be any number
+    of RCPT TO commands, specifying multiple senders. We build them all into
+    a data structure that is in argc/argv format. The start/end values
+    given by parse_extract_address are not used, as we keep only the
+    extracted address. */
+
+    case RCPT_CMD:
+      if (!sender_address)
+	/* The function moan_smtp_batch() does not return. */
+	moan_smtp_batch(smtp_cmd_buffer, "503 No sender yet given");
+
+      if (smtp_cmd_data[0] == 0)
+	/* The function moan_smtp_batch() does not return. */
+	moan_smtp_batch(smtp_cmd_buffer,
+	  "501 RCPT TO must have an address operand");
+
+      /* Check maximum number allowed */
+
+      if (recipients_max > 0 && recipients_count + 1 > recipients_max)
+	/* The function moan_smtp_batch() does not return. */
+	moan_smtp_batch(smtp_cmd_buffer, "%s too many recipients",
+	  recipients_max_reject? "552": "452");
+
+      /* Apply SMTP rewrite, then extract address. Don't allow "<>" as a
+      recipient address */
+
+      recipient = rewrite_existflags & rewrite_smtp
+	/* deconst ok as smtp_cmd_data was not const */
+	? US rewrite_one(smtp_cmd_data, rewrite_smtp, NULL, FALSE, US"",
+		      global_rewrite_rules)
+	: smtp_cmd_data;
+
+      recipient = parse_extract_address(recipient, &errmess, &start, &end,
+	&recipient_domain, FALSE);
+
+      if (!recipient)
+	/* The function moan_smtp_batch() does not return. */
+	moan_smtp_batch(smtp_cmd_buffer, "501 %s", errmess);
+
+      /* If the recipient address is unqualified, qualify it if permitted. Then
+      add it to the list of recipients. */
+
+      if (!recipient_domain)
+	if (f.allow_unqualified_recipient)
+	  {
+	  DEBUG(D_receive) debug_printf("unqualified address %s accepted\n",
+	    recipient);
+	  /* deconst ok as recipient was not const */
+	  recipient = US rewrite_address_qualify(recipient, TRUE);
+	  }
+	/* The function moan_smtp_batch() does not return. */
+	else
+	  moan_smtp_batch(smtp_cmd_buffer,
+	    "501 recipient address must contain a domain");
+
+      receive_add_recipient(recipient, -1);
+      break;
+
+
+    /* The DATA command is legal only if it follows successful MAIL FROM
+    and RCPT TO commands. This function is complete when a valid DATA
+    command is encountered. */
+
+    case DATA_CMD:
+      if (!sender_address || recipients_count <= 0)
+	/* The function moan_smtp_batch() does not return. */
+	if (!sender_address)
+	  moan_smtp_batch(smtp_cmd_buffer,
+	    "503 MAIL FROM:<sender> command must precede DATA");
+	else
+	  moan_smtp_batch(smtp_cmd_buffer,
+	    "503 RCPT TO:<recipient> must precede DATA");
+      else
+	{
+	done = 3;                      /* DATA successfully achieved */
+	message_ended = END_NOTENDED;  /* Indicate in middle of message */
+	}
+      break;
+
+
+    /* The VRFY, EXPN, HELP, ETRN, and NOOP commands are ignored. */
+
+    case VRFY_CMD:
+    case EXPN_CMD:
+    case HELP_CMD:
+    case NOOP_CMD:
+    case ETRN_CMD:
+      bsmtp_transaction_linecount = receive_linecount;
+      break;
+
+
+    case QUIT_CMD:
+      f.smtp_in_quit = TRUE;
+    case EOF_CMD:
+      done = 2;
+      break;
+
+
+    case BADARG_CMD:
+      /* The function moan_smtp_batch() does not return. */
+      moan_smtp_batch(smtp_cmd_buffer, "501 Unexpected argument data");
+      break;
+
+
+    case BADCHAR_CMD:
+      /* The function moan_smtp_batch() does not return. */
+      moan_smtp_batch(smtp_cmd_buffer, "501 Unexpected NULL in SMTP command");
+      break;
+
+
+    default:
+      /* The function moan_smtp_batch() does not return. */
+      moan_smtp_batch(smtp_cmd_buffer, "500 Command unrecognized");
+      break;
+    }
+  }
+
+return done - 2;  /* Convert yield values */
+}
+
+
+
+
+#ifndef DISABLE_TLS
+static BOOL
+smtp_log_tls_fail(const uschar * errstr)
+{
+const uschar * conn_info = smtp_get_connection_info();
+
+if (Ustrncmp(conn_info, US"SMTP ", 5) == 0) conn_info += 5;
+/* I'd like to get separated H= here, but too hard for now */
+
+log_write(0, LOG_MAIN, "TLS error on %s %s", conn_info, errstr);
+return FALSE;
+}
+#endif
+
+
+
+
+#ifdef TCP_FASTOPEN
+static void
+tfo_in_check(void)
+{
+# ifdef __FreeBSD__
+int is_fastopen;
+socklen_t len = sizeof(is_fastopen);
+
+/* The tinfo TCPOPT_FAST_OPEN bit seems unreliable, and we don't see state
+TCP_SYN_RCV (as of 12.1) so no idea about data-use. */
+
+if (getsockopt(fileno(smtp_out), IPPROTO_TCP, TCP_FASTOPEN, &is_fastopen, &len) == 0)
+  {
+  if (is_fastopen)
+    {
+    DEBUG(D_receive)
+      debug_printf("TFO mode connection (TCP_FASTOPEN getsockopt)\n");
+    f.tcp_in_fastopen = TRUE;
+    }
+  }
+else DEBUG(D_receive)
+  debug_printf("TCP_INFO getsockopt: %s\n", strerror(errno));
+
+# elif defined(TCP_INFO)
+struct tcp_info tinfo;
+socklen_t len = sizeof(tinfo);
+
+if (getsockopt(fileno(smtp_out), IPPROTO_TCP, TCP_INFO, &tinfo, &len) == 0)
+#  ifdef TCPI_OPT_SYN_DATA	/* FreeBSD 11,12 do not seem to have this yet */
+  if (tinfo.tcpi_options & TCPI_OPT_SYN_DATA)
+    {
+    DEBUG(D_receive)
+      debug_printf("TFO mode connection (ACKd data-on-SYN)\n");
+    f.tcp_in_fastopen_data = f.tcp_in_fastopen = TRUE;
+    }
+  else
+#  endif
+    if (tinfo.tcpi_state == TCP_SYN_RECV)	/* Not seen on FreeBSD 12.1 */
+    {
+    DEBUG(D_receive)
+      debug_printf("TFO mode connection (state TCP_SYN_RECV)\n");
+    f.tcp_in_fastopen = TRUE;
+    }
+else DEBUG(D_receive)
+  debug_printf("TCP_INFO getsockopt: %s\n", strerror(errno));
+# endif
+}
+#endif
+
+
+/*************************************************
+*          Start an SMTP session                 *
+*************************************************/
+
+/* This function is called at the start of an SMTP session. Thereafter,
+smtp_setup_msg() is called to initiate each separate message. This
+function does host-specific testing, and outputs the banner line.
+
+Arguments:     none
+Returns:       FALSE if the session can not continue; something has
+               gone wrong, or the connection to the host is blocked
+*/
+
+BOOL
+smtp_start_session(void)
+{
+int esclen;
+uschar *user_msg, *log_msg;
+uschar *code, *esc;
+uschar *p, *s;
+gstring * ss;
+
+gettimeofday(&smtp_connection_start, NULL);
+for (smtp_ch_index = 0; smtp_ch_index < SMTP_HBUFF_SIZE; smtp_ch_index++)
+  smtp_connection_had[smtp_ch_index] = SCH_NONE;
+smtp_ch_index = 0;
+
+/* Default values for certain variables */
+
+fl.helo_seen = fl.esmtp = fl.helo_accept_junk = FALSE;
+smtp_mailcmd_count = 0;
+count_nonmail = TRUE_UNSET;
+synprot_error_count = unknown_command_count = nonmail_command_count = 0;
+smtp_delay_mail = smtp_rlm_base;
+fl.auth_advertised = FALSE;
+f.smtp_in_pipelining_advertised = f.smtp_in_pipelining_used = FALSE;
+f.pipelining_enable = TRUE;
+sync_cmd_limit = NON_SYNC_CMD_NON_PIPELINING;
+fl.smtp_exit_function_called = FALSE;    /* For avoiding loop in not-quit exit */
+
+/* If receiving by -bs from a trusted user, or testing with -bh, we allow
+authentication settings from -oMaa to remain in force. */
+
+if (!host_checking && !f.sender_host_notsocket)
+  sender_host_auth_pubname = sender_host_authenticated = NULL;
+authenticated_by = NULL;
+
+#ifndef DISABLE_TLS
+tls_in.ver = tls_in.cipher = tls_in.peerdn = NULL;
+tls_in.ourcert = tls_in.peercert = NULL;
+tls_in.sni = NULL;
+tls_in.ocsp = OCSP_NOT_REQ;
+fl.tls_advertised = FALSE;
+#endif
+fl.dsn_advertised = FALSE;
+#ifdef SUPPORT_I18N
+fl.smtputf8_advertised = FALSE;
+#endif
+
+/* Reset ACL connection variables */
+
+acl_var_c = NULL;
+
+/* Allow for trailing 0 in the command and data buffers.  Tainted. */
+
+smtp_cmd_buffer = store_get_perm(2*SMTP_CMD_BUFFER_SIZE + 2, GET_TAINTED);
+
+smtp_cmd_buffer[0] = 0;
+smtp_data_buffer = smtp_cmd_buffer + SMTP_CMD_BUFFER_SIZE + 1;
+
+/* For batched input, the protocol setting can be overridden from the
+command line by a trusted caller. */
+
+if (smtp_batched_input)
+  {
+  if (!received_protocol) received_protocol = US"local-bsmtp";
+  }
+
+/* For non-batched SMTP input, the protocol setting is forced here. It will be
+reset later if any of EHLO/AUTH/STARTTLS are received. */
+
+else
+  received_protocol =
+    (sender_host_address ? protocols : protocols_local) [pnormal];
+
+/* Set up the buffer for inputting using direct read() calls, and arrange to
+call the local functions instead of the standard C ones. */
+
+smtp_buf_init();
+
+receive_getc = smtp_getc;
+receive_getbuf = smtp_getbuf;
+receive_get_cache = smtp_get_cache;
+receive_hasc = smtp_hasc;
+receive_ungetc = smtp_ungetc;
+receive_feof = smtp_feof;
+receive_ferror = smtp_ferror;
+lwr_receive_getc = NULL;
+lwr_receive_getbuf = NULL;
+lwr_receive_hasc = NULL;
+lwr_receive_ungetc = NULL;
+
+/* Set up the message size limit; this may be host-specific */
+
+thismessage_size_limit = expand_string_integer(message_size_limit, TRUE);
+if (expand_string_message)
+  {
+  if (thismessage_size_limit == -1)
+    log_write(0, LOG_MAIN|LOG_PANIC, "unable to expand message_size_limit: "
+      "%s", expand_string_message);
+  else
+    log_write(0, LOG_MAIN|LOG_PANIC, "invalid message_size_limit: "
+      "%s", expand_string_message);
+  smtp_closedown(US"Temporary local problem - please try later");
+  return FALSE;
+  }
+
+/* When a message is input locally via the -bs or -bS options, sender_host_
+unknown is set unless -oMa was used to force an IP address, in which case it
+is checked like a real remote connection. When -bs is used from inetd, this
+flag is not set, causing the sending host to be checked. The code that deals
+with IP source routing (if configured) is never required for -bs or -bS and
+the flag sender_host_notsocket is used to suppress it.
+
+If smtp_accept_max and smtp_accept_reserve are set, keep some connections in
+reserve for certain hosts and/or networks. */
+
+if (!f.sender_host_unknown)
+  {
+  int rc;
+  BOOL reserved_host = FALSE;
+
+  /* Look up IP options (source routing info) on the socket if this is not an
+  -oMa "host", and if any are found, log them and drop the connection.
+
+  Linux (and others now, see below) is different to everyone else, so there
+  has to be some conditional compilation here. Versions of Linux before 2.1.15
+  used a structure whose name was "options". Somebody finally realized that
+  this name was silly, and it got changed to "ip_options". I use the
+  newer name here, but there is a fudge in the script that sets up os.h
+  to define a macro in older Linux systems.
+
+  Sigh. Linux is a fast-moving target. Another generation of Linux uses
+  glibc 2, which has chosen ip_opts for the structure name. This is now
+  really a glibc thing rather than a Linux thing, so the condition name
+  has been changed to reflect this. It is relevant also to GNU/Hurd.
+
+  Mac OS 10.x (Darwin) is like the later glibc versions, but without the
+  setting of the __GLIBC__ macro, so we can't detect it automatically. There's
+  a special macro defined in the os.h file.
+
+  Some DGUX versions on older hardware appear not to support IP options at
+  all, so there is now a general macro which can be set to cut out this
+  support altogether.
+
+  How to do this properly in IPv6 is not yet known. */
+
+#if !HAVE_IPV6 && !defined(NO_IP_OPTIONS)
+
+  #ifdef GLIBC_IP_OPTIONS
+    #if (!defined __GLIBC__) || (__GLIBC__ < 2)
+    #define OPTSTYLE 1
+    #else
+    #define OPTSTYLE 2
+    #endif
+  #elif defined DARWIN_IP_OPTIONS
+    #define OPTSTYLE 2
+  #else
+    #define OPTSTYLE 3
+  #endif
+
+  if (!host_checking && !f.sender_host_notsocket)
+    {
+    #if OPTSTYLE == 1
+    EXIM_SOCKLEN_T optlen = sizeof(struct ip_options) + MAX_IPOPTLEN;
+    struct ip_options *ipopt = store_get(optlen, GET_UNTAINTED);
+    #elif OPTSTYLE == 2
+    struct ip_opts ipoptblock;
+    struct ip_opts *ipopt = &ipoptblock;
+    EXIM_SOCKLEN_T optlen = sizeof(ipoptblock);
+    #else
+    struct ipoption ipoptblock;
+    struct ipoption *ipopt = &ipoptblock;
+    EXIM_SOCKLEN_T optlen = sizeof(ipoptblock);
+    #endif
+
+    /* Occasional genuine failures of getsockopt() have been seen - for
+    example, "reset by peer". Therefore, just log and give up on this
+    call, unless the error is ENOPROTOOPT. This error is given by systems
+    that have the interfaces but not the mechanism - e.g. GNU/Hurd at the time
+    of writing. So for that error, carry on - we just can't do an IP options
+    check. */
+
+    DEBUG(D_receive) debug_printf("checking for IP options\n");
+
+    if (getsockopt(fileno(smtp_out), IPPROTO_IP, IP_OPTIONS, US (ipopt),
+          &optlen) < 0)
+      {
+      if (errno != ENOPROTOOPT)
+        {
+        log_write(0, LOG_MAIN, "getsockopt() failed from %s: %s",
+          host_and_ident(FALSE), strerror(errno));
+        smtp_printf("451 SMTP service not available\r\n", FALSE);
+        return FALSE;
+        }
+      }
+
+    /* Deal with any IP options that are set. On the systems I have looked at,
+    the value of MAX_IPOPTLEN has been 40, meaning that there should never be
+    more logging data than will fit in big_buffer. Nevertheless, after somebody
+    questioned this code, I've added in some paranoid checking. */
+
+    else if (optlen > 0)
+      {
+      uschar *p = big_buffer;
+      uschar *pend = big_buffer + big_buffer_size;
+      uschar *adptr;
+      int optcount;
+      struct in_addr addr;
+
+      #if OPTSTYLE == 1
+      uschar *optstart = US (ipopt->__data);
+      #elif OPTSTYLE == 2
+      uschar *optstart = US (ipopt->ip_opts);
+      #else
+      uschar *optstart = US (ipopt->ipopt_list);
+      #endif
+
+      DEBUG(D_receive) debug_printf("IP options exist\n");
+
+      Ustrcpy(p, "IP options on incoming call:");
+      p += Ustrlen(p);
+
+      for (uschar * opt = optstart; opt && opt < US (ipopt) + optlen; )
+        switch (*opt)
+          {
+          case IPOPT_EOL:
+          opt = NULL;
+          break;
+
+          case IPOPT_NOP:
+          opt++;
+          break;
+
+          case IPOPT_SSRR:
+          case IPOPT_LSRR:
+          if (!string_format(p, pend-p, " %s [@%s",
+               (*opt == IPOPT_SSRR)? "SSRR" : "LSRR",
+               #if OPTSTYLE == 1
+               inet_ntoa(*((struct in_addr *)(&(ipopt->faddr))))))
+               #elif OPTSTYLE == 2
+               inet_ntoa(ipopt->ip_dst)))
+               #else
+               inet_ntoa(ipopt->ipopt_dst)))
+               #endif
+            {
+            opt = NULL;
+            break;
+            }
+
+          p += Ustrlen(p);
+          optcount = (opt[1] - 3) / sizeof(struct in_addr);
+          adptr = opt + 3;
+          while (optcount-- > 0)
+            {
+            memcpy(&addr, adptr, sizeof(addr));
+            if (!string_format(p, pend - p - 1, "%s%s",
+                  (optcount == 0)? ":" : "@", inet_ntoa(addr)))
+              {
+              opt = NULL;
+              break;
+              }
+            p += Ustrlen(p);
+            adptr += sizeof(struct in_addr);
+            }
+          *p++ = ']';
+          opt += opt[1];
+          break;
+
+          default:
+            {
+            if (pend - p < 4 + 3*opt[1]) { opt = NULL; break; }
+            Ustrcat(p, "[ ");
+            p += 2;
+            for (int i = 0; i < opt[1]; i++)
+              p += sprintf(CS p, "%2.2x ", opt[i]);
+            *p++ = ']';
+            }
+          opt += opt[1];
+          break;
+          }
+
+      *p = 0;
+      log_write(0, LOG_MAIN, "%s", big_buffer);
+
+      /* Refuse any call with IP options. This is what tcpwrappers 7.5 does. */
+
+      log_write(0, LOG_MAIN|LOG_REJECT,
+        "connection from %s refused (IP options)", host_and_ident(FALSE));
+
+      smtp_printf("554 SMTP service not available\r\n", FALSE);
+      return FALSE;
+      }
+
+    /* Length of options = 0 => there are no options */
+
+    else DEBUG(D_receive) debug_printf("no IP options found\n");
+    }
+#endif  /* HAVE_IPV6 && !defined(NO_IP_OPTIONS) */
+
+  /* Set keep-alive in socket options. The option is on by default. This
+  setting is an attempt to get rid of some hanging connections that stick in
+  read() when the remote end (usually a dialup) goes away. */
+
+  if (smtp_accept_keepalive && !f.sender_host_notsocket)
+    ip_keepalive(fileno(smtp_out), sender_host_address, FALSE);
+
+  /* If the current host matches host_lookup, set the name by doing a
+  reverse lookup. On failure, sender_host_name will be NULL and
+  host_lookup_failed will be TRUE. This may or may not be serious - optional
+  checks later. */
+
+  if (verify_check_host(&host_lookup) == OK)
+    {
+    (void)host_name_lookup();
+    host_build_sender_fullhost();
+    }
+
+  /* Delay this until we have the full name, if it is looked up. */
+
+  set_process_info("handling incoming connection from %s",
+    host_and_ident(FALSE));
+
+  /* Expand smtp_receive_timeout, if needed */
+
+  if (smtp_receive_timeout_s)
+    {
+    uschar * exp;
+    if (  !(exp = expand_string(smtp_receive_timeout_s))
+       || !(*exp)
+       || (smtp_receive_timeout = readconf_readtime(exp, 0, FALSE)) < 0
+       )
+      log_write(0, LOG_MAIN|LOG_PANIC,
+	"bad value for smtp_receive_timeout: '%s'", exp ? exp : US"");
+    }
+
+  /* Test for explicit connection rejection */
+
+  if (verify_check_host(&host_reject_connection) == OK)
+    {
+    log_write(L_connection_reject, LOG_MAIN|LOG_REJECT, "refused connection "
+      "from %s (host_reject_connection)", host_and_ident(FALSE));
+    smtp_printf("554 SMTP service not available\r\n", FALSE);
+    return FALSE;
+    }
+
+  /* Test with TCP Wrappers if so configured. There is a problem in that
+  hosts_ctl() returns 0 (deny) under a number of system failure circumstances,
+  such as disks dying. In these cases, it is desirable to reject with a 4xx
+  error instead of a 5xx error. There isn't a "right" way to detect such
+  problems. The following kludge is used: errno is zeroed before calling
+  hosts_ctl(). If the result is "reject", a 5xx error is given only if the
+  value of errno is 0 or ENOENT (which happens if /etc/hosts.{allow,deny} does
+  not exist). */
+
+#ifdef USE_TCP_WRAPPERS
+  errno = 0;
+  if (!(tcp_wrappers_name = expand_string(tcp_wrappers_daemon_name)))
+    log_write(0, LOG_MAIN|LOG_PANIC_DIE, "Expansion of \"%s\" "
+      "(tcp_wrappers_name) failed: %s", string_printing(tcp_wrappers_name),
+        expand_string_message);
+
+  if (!hosts_ctl(tcp_wrappers_name,
+         sender_host_name ? CS sender_host_name : STRING_UNKNOWN,
+         sender_host_address ? CS sender_host_address : STRING_UNKNOWN,
+         sender_ident ? CS sender_ident : STRING_UNKNOWN))
+    {
+    if (errno == 0 || errno == ENOENT)
+      {
+      HDEBUG(D_receive) debug_printf("tcp wrappers rejection\n");
+      log_write(L_connection_reject,
+                LOG_MAIN|LOG_REJECT, "refused connection from %s "
+                "(tcp wrappers)", host_and_ident(FALSE));
+      smtp_printf("554 SMTP service not available\r\n", FALSE);
+      }
+    else
+      {
+      int save_errno = errno;
+      HDEBUG(D_receive) debug_printf("tcp wrappers rejected with unexpected "
+        "errno value %d\n", save_errno);
+      log_write(L_connection_reject,
+                LOG_MAIN|LOG_REJECT, "temporarily refused connection from %s "
+                "(tcp wrappers errno=%d)", host_and_ident(FALSE), save_errno);
+      smtp_printf("451 Temporary local problem - please try later\r\n", FALSE);
+      }
+    return FALSE;
+    }
+#endif
+
+  /* Check for reserved slots. The value of smtp_accept_count has already been
+  incremented to include this process. */
+
+  if (smtp_accept_max > 0 &&
+      smtp_accept_count > smtp_accept_max - smtp_accept_reserve)
+    {
+    if ((rc = verify_check_host(&smtp_reserve_hosts)) != OK)
+      {
+      log_write(L_connection_reject,
+        LOG_MAIN, "temporarily refused connection from %s: not in "
+        "reserve list: connected=%d max=%d reserve=%d%s",
+        host_and_ident(FALSE), smtp_accept_count - 1, smtp_accept_max,
+        smtp_accept_reserve, (rc == DEFER)? " (lookup deferred)" : "");
+      smtp_printf("421 %s: Too many concurrent SMTP connections; "
+        "please try again later\r\n", FALSE, smtp_active_hostname);
+      return FALSE;
+      }
+    reserved_host = TRUE;
+    }
+
+  /* If a load level above which only messages from reserved hosts are
+  accepted is set, check the load. For incoming calls via the daemon, the
+  check is done in the superior process if there are no reserved hosts, to
+  save a fork. In all cases, the load average will already be available
+  in a global variable at this point. */
+
+  if (smtp_load_reserve >= 0 &&
+       load_average > smtp_load_reserve &&
+       !reserved_host &&
+       verify_check_host(&smtp_reserve_hosts) != OK)
+    {
+    log_write(L_connection_reject,
+      LOG_MAIN, "temporarily refused connection from %s: not in "
+      "reserve list and load average = %.2f", host_and_ident(FALSE),
+      (double)load_average/1000.0);
+    smtp_printf("421 %s: Too much load; please try again later\r\n", FALSE,
+      smtp_active_hostname);
+    return FALSE;
+    }
+
+  /* Determine whether unqualified senders or recipients are permitted
+  for this host. Unfortunately, we have to do this every time, in order to
+  set the flags so that they can be inspected when considering qualifying
+  addresses in the headers. For a site that permits no qualification, this
+  won't take long, however. */
+
+  f.allow_unqualified_sender =
+    verify_check_host(&sender_unqualified_hosts) == OK;
+
+  f.allow_unqualified_recipient =
+    verify_check_host(&recipient_unqualified_hosts) == OK;
+
+  /* Determine whether HELO/EHLO is required for this host. The requirement
+  can be hard or soft. */
+
+  fl.helo_verify_required = verify_check_host(&helo_verify_hosts) == OK;
+  if (!fl.helo_verify_required)
+    fl.helo_verify = verify_check_host(&helo_try_verify_hosts) == OK;
+
+  /* Determine whether this hosts is permitted to send syntactic junk
+  after a HELO or EHLO command. */
+
+  fl.helo_accept_junk = verify_check_host(&helo_accept_junk_hosts) == OK;
+  }
+
+/* For batch SMTP input we are now done. */
+
+if (smtp_batched_input) return TRUE;
+
+/* If valid Proxy Protocol source is connecting, set up session.
+Failure will not allow any SMTP function other than QUIT. */
+
+#ifdef SUPPORT_PROXY
+proxy_session = FALSE;
+f.proxy_session_failed = FALSE;
+if (check_proxy_protocol_host())
+  setup_proxy_protocol_host();
+#endif
+
+/* Start up TLS if tls_on_connect is set. This is for supporting the legacy
+smtps port for use with older style SSL MTAs. */
+
+#ifndef DISABLE_TLS
+if (tls_in.on_connect)
+  {
+  if (tls_server_start(&user_msg) != OK)
+    return smtp_log_tls_fail(user_msg);
+  cmd_list[CMD_LIST_TLS_AUTH].is_mail_cmd = TRUE;
+  }
+#endif
+
+/* Run the connect ACL if it exists */
+
+user_msg = NULL;
+if (acl_smtp_connect)
+  {
+  int rc;
+  if ((rc = acl_check(ACL_WHERE_CONNECT, NULL, acl_smtp_connect, &user_msg,
+		      &log_msg)) != OK)
+    {
+    (void) smtp_handle_acl_fail(ACL_WHERE_CONNECT, rc, user_msg, log_msg);
+    return FALSE;
+    }
+  }
+
+/* Output the initial message for a two-way SMTP connection. It may contain
+newlines, which then cause a multi-line response to be given. */
+
+code = US"220";   /* Default status code */
+esc = US"";       /* Default extended status code */
+esclen = 0;       /* Length of esc */
+
+if (!user_msg)
+  {
+  if (!(s = expand_string(smtp_banner)))
+    log_write(0, LOG_MAIN|LOG_PANIC_DIE, "Expansion of \"%s\" (smtp_banner) "
+      "failed: %s", smtp_banner, expand_string_message);
+  }
+else
+  {
+  int codelen = 3;
+  s = user_msg;
+  smtp_message_code(&code, &codelen, &s, NULL, TRUE);
+  if (codelen > 4)
+    {
+    esc = code + 4;
+    esclen = codelen - 4;
+    }
+  }
+
+/* Remove any terminating newlines; might as well remove trailing space too */
+
+p = s + Ustrlen(s);
+while (p > s && isspace(p[-1])) p--;
+s = string_copyn(s, p-s);
+
+/* It seems that CC:Mail is braindead, and assumes that the greeting message
+is all contained in a single IP packet. The original code wrote out the
+greeting using several calls to fprint/fputc, and on busy servers this could
+cause it to be split over more than one packet - which caused CC:Mail to fall
+over when it got the second part of the greeting after sending its first
+command. Sigh. To try to avoid this, build the complete greeting message
+first, and output it in one fell swoop. This gives a better chance of it
+ending up as a single packet. */
+
+ss = string_get(256);
+
+p = s;
+do       /* At least once, in case we have an empty string */
+  {
+  int len;
+  uschar *linebreak = Ustrchr(p, '\n');
+  ss = string_catn(ss, code, 3);
+  if (!linebreak)
+    {
+    len = Ustrlen(p);
+    ss = string_catn(ss, US" ", 1);
+    }
+  else
+    {
+    len = linebreak - p;
+    ss = string_catn(ss, US"-", 1);
+    }
+  ss = string_catn(ss, esc, esclen);
+  ss = string_catn(ss, p, len);
+  ss = string_catn(ss, US"\r\n", 2);
+  p += len;
+  if (linebreak) p++;
+  }
+while (*p);
+
+/* Before we write the banner, check that there is no input pending, unless
+this synchronisation check is disabled. */
+
+#ifndef DISABLE_PIPE_CONNECT
+fl.pipe_connect_acceptable =
+  sender_host_address && verify_check_host(&pipe_connect_advertise_hosts) == OK;
+
+if (!check_sync())
+  if (fl.pipe_connect_acceptable)
+    f.smtp_in_early_pipe_used = TRUE;
+  else
+#else
+if (!check_sync())
+#endif
+    {
+    unsigned n = smtp_inend - smtp_inptr;
+    if (n > 128) n = 128;
+
+    log_write(0, LOG_MAIN|LOG_REJECT, "SMTP protocol "
+      "synchronization error (input sent without waiting for greeting): "
+      "rejected connection from %s input=\"%s\"", host_and_ident(TRUE),
+      string_printing(string_copyn(smtp_inptr, n)));
+    smtp_printf("554 SMTP synchronization error\r\n", FALSE);
+    return FALSE;
+    }
+
+/* Now output the banner */
+/*XXX the ehlo-resp code does its own tls/nontls bit.  Maybe subroutine that? */
+
+smtp_printf("%s",
+#ifndef DISABLE_PIPE_CONNECT
+  fl.pipe_connect_acceptable && pipeline_connect_sends(),
+#else
+  FALSE,
+#endif
+  string_from_gstring(ss));
+
+/* Attempt to see if we sent the banner before the last ACK of the 3-way
+handshake arrived.  If so we must have managed a TFO. */
+
+#ifdef TCP_FASTOPEN
+if (sender_host_address && !f.sender_host_notsocket) tfo_in_check();
+#endif
+
+return TRUE;
+}
+
+
+
+
+
+/*************************************************
+*     Handle SMTP syntax and protocol errors     *
+*************************************************/
+
+/* Write to the log for SMTP syntax errors in incoming commands, if configured
+to do so. Then transmit the error response. The return value depends on the
+number of syntax and protocol errors in this SMTP session.
+
+Arguments:
+  type      error type, given as a log flag bit
+  code      response code; <= 0 means don't send a response
+  data      data to reflect in the response (can be NULL)
+  errmess   the error message
+
+Returns:    -1   limit of syntax/protocol errors NOT exceeded
+            +1   limit of syntax/protocol errors IS exceeded
+
+These values fit in with the values of the "done" variable in the main
+processing loop in smtp_setup_msg(). */
+
+static int
+synprot_error(int type, int code, uschar *data, uschar *errmess)
+{
+int yield = -1;
+
+log_write(type, LOG_MAIN, "SMTP %s error in \"%s\" %s %s",
+  type == L_smtp_syntax_error ? "syntax" : "protocol",
+  string_printing(smtp_cmd_buffer), host_and_ident(TRUE), errmess);
+
+if (++synprot_error_count > smtp_max_synprot_errors)
+  {
+  yield = 1;
+  log_write(0, LOG_MAIN|LOG_REJECT, "SMTP call from %s dropped: too many "
+    "syntax or protocol errors (last command was \"%s\", %s)",
+    host_and_ident(FALSE), string_printing(smtp_cmd_buffer),
+    string_from_gstring(s_connhad_log(NULL))
+    );
+  }
+
+if (code > 0)
+  {
+  smtp_printf("%d%c%s%s%s\r\n", FALSE, code, yield == 1 ? '-' : ' ',
+    data ? data : US"", data ? US": " : US"", errmess);
+  if (yield == 1)
+    smtp_printf("%d Too many syntax or protocol errors\r\n", FALSE, code);
+  }
+
+return yield;
+}
+
+
+
+
+/*************************************************
+*    Send SMTP response, possibly multiline      *
+*************************************************/
+
+/* There are, it seems, broken clients out there that cannot handle multiline
+responses. If no_multiline_responses is TRUE (it can be set from an ACL), we
+output nothing for non-final calls, and only the first line for anything else.
+
+Arguments:
+  code          SMTP code, may involve extended status codes
+  codelen       length of smtp code; if > 4 there's an ESC
+  final         FALSE if the last line isn't the final line
+  msg           message text, possibly containing newlines
+
+Returns:        nothing
+*/
+
+void
+smtp_respond(uschar* code, int codelen, BOOL final, uschar *msg)
+{
+int esclen = 0;
+uschar *esc = US"";
+
+if (!final && f.no_multiline_responses) return;
+
+if (codelen > 4)
+  {
+  esc = code + 4;
+  esclen = codelen - 4;
+  }
+
+/* If this is the first output for a (non-batch) RCPT command, see if all RCPTs
+have had the same. Note: this code is also present in smtp_printf(). It would
+be tidier to have it only in one place, but when it was added, it was easier to
+do it that way, so as not to have to mess with the code for the RCPT command,
+which sometimes uses smtp_printf() and sometimes smtp_respond(). */
+
+if (fl.rcpt_in_progress)
+  {
+  if (!rcpt_smtp_response)
+    rcpt_smtp_response = string_copy(msg);
+  else if (fl.rcpt_smtp_response_same &&
+           Ustrcmp(rcpt_smtp_response, msg) != 0)
+    fl.rcpt_smtp_response_same = FALSE;
+  fl.rcpt_in_progress = FALSE;
+  }
+
+/* Now output the message, splitting it up into multiple lines if necessary.
+We only handle pipelining these responses as far as nonfinal/final groups,
+not the whole MAIL/RCPT/DATA response set. */
+
+for (;;)
+  {
+  uschar *nl = Ustrchr(msg, '\n');
+  if (!nl)
+    {
+    smtp_printf("%.3s%c%.*s%s\r\n", !final, code, final ? ' ':'-', esclen, esc, msg);
+    return;
+    }
+  else if (nl[1] == 0 || f.no_multiline_responses)
+    {
+    smtp_printf("%.3s%c%.*s%.*s\r\n", !final, code, final ? ' ':'-', esclen, esc,
+      (int)(nl - msg), msg);
+    return;
+    }
+  else
+    {
+    smtp_printf("%.3s-%.*s%.*s\r\n", TRUE, code, esclen, esc, (int)(nl - msg), msg);
+    msg = nl + 1;
+    Uskip_whitespace(&msg);
+    }
+  }
+}
+
+
+
+
+/*************************************************
+*            Parse user SMTP message             *
+*************************************************/
+
+/* This function allows for user messages overriding the response code details
+by providing a suitable response code string at the start of the message
+user_msg. Check the message for starting with a response code and optionally an
+extended status code. If found, check that the first digit is valid, and if so,
+change the code pointer and length to use the replacement. An invalid code
+causes a panic log; in this case, if the log messages is the same as the user
+message, we must also adjust the value of the log message to show the code that
+is actually going to be used (the original one).
+
+This function is global because it is called from receive.c as well as within
+this module.
+
+Note that the code length returned includes the terminating whitespace
+character, which is always included in the regex match.
+
+Arguments:
+  code          SMTP code, may involve extended status codes
+  codelen       length of smtp code; if > 4 there's an ESC
+  msg           message text
+  log_msg       optional log message, to be adjusted with the new SMTP code
+  check_valid   if true, verify the response code
+
+Returns:        nothing
+*/
+
+void
+smtp_message_code(uschar **code, int *codelen, uschar **msg, uschar **log_msg,
+  BOOL check_valid)
+{
+uschar * match;
+int len;
+
+if (!msg || !*msg || !regex_match(regex_smtp_code, *msg, -1, &match))
+  return;
+
+len = Ustrlen(match);
+if (check_valid && (*msg)[0] != (*code)[0])
+  {
+  log_write(0, LOG_MAIN|LOG_PANIC, "configured error code starts with "
+    "incorrect digit (expected %c) in \"%s\"", (*code)[0], *msg);
+  if (log_msg && *log_msg == *msg)
+    *log_msg = string_sprintf("%s %s", *code, *log_msg + len);
+  }
+else
+  {
+  *code = *msg;
+  *codelen = len;    /* Includes final space */
+  }
+*msg += len;         /* Chop the code off the message */
+return;
+}
+
+
+
+
+/*************************************************
+*           Handle an ACL failure                *
+*************************************************/
+
+/* This function is called when acl_check() fails. As well as calls from within
+this module, it is called from receive.c for an ACL after DATA. It sorts out
+logging the incident, and sends the error response. A message containing
+newlines is turned into a multiline SMTP response, but for logging, only the
+first line is used.
+
+There's a table of default permanent failure response codes to use in
+globals.c, along with the table of names. VFRY is special. Despite RFC1123 it
+defaults disabled in Exim. However, discussion in connection with RFC 821bis
+(aka RFC 2821) has concluded that the response should be 252 in the disabled
+state, because there are broken clients that try VRFY before RCPT. A 5xx
+response should be given only when the address is positively known to be
+undeliverable. Sigh. We return 252 if there is no VRFY ACL or it provides
+no explicit code, but if there is one we let it know best.
+Also, for ETRN, 458 is given on refusal, and for AUTH, 503.
+
+From Exim 4.63, it is possible to override the response code details by
+providing a suitable response code string at the start of the message provided
+in user_msg. The code's first digit is checked for validity.
+
+Arguments:
+  where        where the ACL was called from
+  rc           the failure code
+  user_msg     a message that can be included in an SMTP response
+  log_msg      a message for logging
+
+Returns:     0 in most cases
+             2 if the failure code was FAIL_DROP, in which case the
+               SMTP connection should be dropped (this value fits with the
+               "done" variable in smtp_setup_msg() below)
+*/
+
+int
+smtp_handle_acl_fail(int where, int rc, uschar *user_msg, uschar *log_msg)
+{
+BOOL drop = rc == FAIL_DROP;
+int codelen = 3;
+uschar *smtp_code;
+uschar *lognl;
+uschar *sender_info = US"";
+uschar *what;
+
+if (drop) rc = FAIL;
+
+/* Set the default SMTP code, and allow a user message to change it. */
+
+smtp_code = rc == FAIL ? acl_wherecodes[where] : US"451";
+smtp_message_code(&smtp_code, &codelen, &user_msg, &log_msg,
+  where != ACL_WHERE_VRFY);
+
+/* We used to have sender_address here; however, there was a bug that was not
+updating sender_address after a rewrite during a verify. When this bug was
+fixed, sender_address at this point became the rewritten address. I'm not sure
+this is what should be logged, so I've changed to logging the unrewritten
+address to retain backward compatibility. */
+
+switch (where)
+  {
+#ifdef WITH_CONTENT_SCAN
+  case ACL_WHERE_MIME:		what = US"during MIME ACL checks";	break;
+#endif
+  case ACL_WHERE_PREDATA:	what = US"DATA";			break;
+  case ACL_WHERE_DATA:		what = US"after DATA";			break;
+#ifndef DISABLE_PRDR
+  case ACL_WHERE_PRDR:		what = US"after DATA PRDR";		break;
+#endif
+  default:
+    {
+    uschar * place = smtp_cmd_data ? smtp_cmd_data : US"in \"connect\" ACL";
+    int lim = 100;
+
+    if (where == ACL_WHERE_AUTH)	/* avoid logging auth creds */
+      {
+      uschar * s;
+      for (s = smtp_cmd_data; *s && !isspace(*s); ) s++;
+      lim = s - smtp_cmd_data;	/* atop after method */
+      }
+    what = string_sprintf("%s %.*s", acl_wherenames[where], lim, place);
+    }
+  }
+switch (where)
+  {
+  case ACL_WHERE_RCPT:
+  case ACL_WHERE_DATA:
+#ifdef WITH_CONTENT_SCAN
+  case ACL_WHERE_MIME:
+#endif
+    sender_info = string_sprintf("F=<%s>%s%s%s%s ",
+      sender_address_unrewritten ? sender_address_unrewritten : sender_address,
+      sender_host_authenticated ? US" A="                                    : US"",
+      sender_host_authenticated ? sender_host_authenticated                  : US"",
+      sender_host_authenticated && authenticated_id ? US":"                  : US"",
+      sender_host_authenticated && authenticated_id ? authenticated_id       : US""
+      );
+  break;
+  }
+
+/* If there's been a sender verification failure with a specific message, and
+we have not sent a response about it yet, do so now, as a preliminary line for
+failures, but not defers. However, always log it for defer, and log it for fail
+unless the sender_verify_fail log selector has been turned off. */
+
+if (sender_verified_failed &&
+    !testflag(sender_verified_failed, af_sverify_told))
+  {
+  BOOL save_rcpt_in_progress = fl.rcpt_in_progress;
+  fl.rcpt_in_progress = FALSE;  /* So as not to treat these as the error */
+
+  setflag(sender_verified_failed, af_sverify_told);
+
+  if (rc != FAIL || LOGGING(sender_verify_fail))
+    log_write(0, LOG_MAIN|LOG_REJECT, "%s sender verify %s for <%s>%s",
+      host_and_ident(TRUE),
+      ((sender_verified_failed->special_action & 255) == DEFER)? "defer":"fail",
+      sender_verified_failed->address,
+      (sender_verified_failed->message == NULL)? US"" :
+      string_sprintf(": %s", sender_verified_failed->message));
+
+  if (rc == FAIL && sender_verified_failed->user_message)
+    smtp_respond(smtp_code, codelen, FALSE, string_sprintf(
+        testflag(sender_verified_failed, af_verify_pmfail)?
+          "Postmaster verification failed while checking <%s>\n%s\n"
+          "Several RFCs state that you are required to have a postmaster\n"
+          "mailbox for each mail domain. This host does not accept mail\n"
+          "from domains whose servers reject the postmaster address."
+          :
+        testflag(sender_verified_failed, af_verify_nsfail)?
+          "Callback setup failed while verifying <%s>\n%s\n"
+          "The initial connection, or a HELO or MAIL FROM:<> command was\n"
+          "rejected. Refusing MAIL FROM:<> does not help fight spam, disregards\n"
+          "RFC requirements, and stops you from receiving standard bounce\n"
+          "messages. This host does not accept mail from domains whose servers\n"
+          "refuse bounces."
+          :
+          "Verification failed for <%s>\n%s",
+        sender_verified_failed->address,
+        sender_verified_failed->user_message));
+
+  fl.rcpt_in_progress = save_rcpt_in_progress;
+  }
+
+/* Sort out text for logging */
+
+log_msg = log_msg ? string_sprintf(": %s", log_msg) : US"";
+if ((lognl = Ustrchr(log_msg, '\n'))) *lognl = 0;
+
+/* Send permanent failure response to the command, but the code used isn't
+always a 5xx one - see comments at the start of this function. If the original
+rc was FAIL_DROP we drop the connection and yield 2. */
+
+if (rc == FAIL)
+  smtp_respond(smtp_code, codelen, TRUE,
+    user_msg ? user_msg : US"Administrative prohibition");
+
+/* Send temporary failure response to the command. Don't give any details,
+unless acl_temp_details is set. This is TRUE for a callout defer, a "defer"
+verb, and for a header verify when smtp_return_error_details is set.
+
+This conditional logic is all somewhat of a mess because of the odd
+interactions between temp_details and return_error_details. One day it should
+be re-implemented in a tidier fashion. */
+
+else
+  if (f.acl_temp_details && user_msg)
+    {
+    if (  smtp_return_error_details
+       && sender_verified_failed
+       && sender_verified_failed->message
+       )
+      smtp_respond(smtp_code, codelen, FALSE, sender_verified_failed->message);
+
+    smtp_respond(smtp_code, codelen, TRUE, user_msg);
+    }
+  else
+    smtp_respond(smtp_code, codelen, TRUE,
+      US"Temporary local problem - please try later");
+
+/* Log the incident to the logs that are specified by log_reject_target
+(default main, reject). This can be empty to suppress logging of rejections. If
+the connection is not forcibly to be dropped, return 0. Otherwise, log why it
+is closing if required and return 2.  */
+
+if (log_reject_target != 0)
+  {
+#ifndef DISABLE_TLS
+  gstring * g = s_tlslog(NULL);
+  uschar * tls = string_from_gstring(g);
+  if (!tls) tls = US"";
+#else
+  uschar * tls = US"";
+#endif
+  log_write(where == ACL_WHERE_CONNECT ? L_connection_reject : 0,
+    log_reject_target, "%s%s%s %s%srejected %s%s",
+    LOGGING(dnssec) && sender_host_dnssec ? US" DS" : US"",
+    host_and_ident(TRUE),
+    tls,
+    sender_info,
+    rc == FAIL ? US"" : US"temporarily ",
+    what, log_msg);
+  }
+
+if (!drop) return 0;
+
+log_write(L_smtp_connection, LOG_MAIN, "%s closed by DROP in ACL",
+  smtp_get_connection_info());
+
+/* Run the not-quit ACL, but without any custom messages. This should not be a
+problem, because we get here only if some other ACL has issued "drop", and
+in that case, *its* custom messages will have been used above. */
+
+smtp_notquit_exit(US"acl-drop", NULL, NULL);
+return 2;
+}
+
+
+
+
+/*************************************************
+*     Handle SMTP exit when QUIT is not given    *
+*************************************************/
+
+/* This function provides a logging/statistics hook for when an SMTP connection
+is dropped on the floor or the other end goes away. It's a global function
+because it's called from receive.c as well as this module. As well as running
+the NOTQUIT ACL, if there is one, this function also outputs a final SMTP
+response, either with a custom message from the ACL, or using a default. There
+is one case, however, when no message is output - after "drop". In that case,
+the ACL that obeyed "drop" has already supplied the custom message, and NULL is
+passed to this function.
+
+In case things go wrong while processing this function, causing an error that
+may re-enter this function, there is a recursion check.
+
+Arguments:
+  reason          What $smtp_notquit_reason will be set to in the ACL;
+                    if NULL, the ACL is not run
+  code            The error code to return as part of the response
+  defaultrespond  The default message if there's no user_msg
+
+Returns:          Nothing
+*/
+
+void
+smtp_notquit_exit(uschar *reason, uschar *code, uschar *defaultrespond, ...)
+{
+int rc;
+uschar *user_msg = NULL;
+uschar *log_msg = NULL;
+
+/* Check for recursive call */
+
+if (fl.smtp_exit_function_called)
+  {
+  log_write(0, LOG_PANIC, "smtp_notquit_exit() called more than once (%s)",
+    reason);
+  return;
+  }
+fl.smtp_exit_function_called = TRUE;
+
+/* Call the not-QUIT ACL, if there is one, unless no reason is given. */
+
+if (acl_smtp_notquit && reason)
+  {
+  smtp_notquit_reason = reason;
+  if ((rc = acl_check(ACL_WHERE_NOTQUIT, NULL, acl_smtp_notquit, &user_msg,
+		      &log_msg)) == ERROR)
+    log_write(0, LOG_MAIN|LOG_PANIC, "ACL for not-QUIT returned ERROR: %s",
+      log_msg);
+  }
+
+/* If the connection was dropped, we certainly are no longer talking TLS */
+tls_in.active.sock = -1;
+
+/* Write an SMTP response if we are expected to give one. As the default
+responses are all internal, they should be reasonable size. */
+
+if (code && defaultrespond)
+  {
+  if (user_msg)
+    smtp_respond(code, 3, TRUE, user_msg);
+  else
+    {
+    gstring * g;
+    va_list ap;
+
+    va_start(ap, defaultrespond);
+    g = string_vformat(NULL, SVFMT_EXTEND|SVFMT_REBUFFER, CS defaultrespond, ap);
+    va_end(ap);
+    smtp_printf("%s %s\r\n", FALSE, code, string_from_gstring(g));
+    }
+  mac_smtp_fflush();
+  }
+}
+
+
+
+
+/*************************************************
+*             Verify HELO argument               *
+*************************************************/
+
+/* This function is called if helo_verify_hosts or helo_try_verify_hosts is
+matched. It is also called from ACL processing if verify = helo is used and
+verification was not previously tried (i.e. helo_try_verify_hosts was not
+matched). The result of its processing is to set helo_verified and
+helo_verify_failed. These variables should both be FALSE for this function to
+be called.
+
+Note that EHLO/HELO is legitimately allowed to quote an address literal. Allow
+for IPv6 ::ffff: literals.
+
+Argument:   none
+Returns:    TRUE if testing was completed;
+            FALSE on a temporary failure
+*/
+
+BOOL
+smtp_verify_helo(void)
+{
+BOOL yield = TRUE;
+
+HDEBUG(D_receive) debug_printf("verifying EHLO/HELO argument \"%s\"\n",
+  sender_helo_name);
+
+if (sender_helo_name == NULL)
+  {
+  HDEBUG(D_receive) debug_printf("no EHLO/HELO command was issued\n");
+  }
+
+/* Deal with the case of -bs without an IP address */
+
+else if (sender_host_address == NULL)
+  {
+  HDEBUG(D_receive) debug_printf("no client IP address: assume success\n");
+  f.helo_verified = TRUE;
+  }
+
+/* Deal with the more common case when there is a sending IP address */
+
+else if (sender_helo_name[0] == '[')
+  {
+  f.helo_verified = Ustrncmp(sender_helo_name+1, sender_host_address,
+    Ustrlen(sender_host_address)) == 0;
+
+#if HAVE_IPV6
+  if (!f.helo_verified)
+    {
+    if (strncmpic(sender_host_address, US"::ffff:", 7) == 0)
+      f.helo_verified = Ustrncmp(sender_helo_name + 1,
+        sender_host_address + 7, Ustrlen(sender_host_address) - 7) == 0;
+    }
+#endif
+
+  HDEBUG(D_receive)
+    { if (f.helo_verified) debug_printf("matched host address\n"); }
+  }
+
+/* Do a reverse lookup if one hasn't already given a positive or negative
+response. If that fails, or the name doesn't match, try checking with a forward
+lookup. */
+
+else
+  {
+  if (sender_host_name == NULL && !host_lookup_failed)
+    yield = host_name_lookup() != DEFER;
+
+  /* If a host name is known, check it and all its aliases. */
+
+  if (sender_host_name)
+    if ((f.helo_verified = strcmpic(sender_host_name, sender_helo_name) == 0))
+      {
+      sender_helo_dnssec = sender_host_dnssec;
+      HDEBUG(D_receive) debug_printf("matched host name\n");
+      }
+    else
+      {
+      uschar **aliases = sender_host_aliases;
+      while (*aliases)
+        if ((f.helo_verified = strcmpic(*aliases++, sender_helo_name) == 0))
+	  {
+	  sender_helo_dnssec = sender_host_dnssec;
+	  break;
+	  }
+
+      HDEBUG(D_receive) if (f.helo_verified)
+          debug_printf("matched alias %s\n", *(--aliases));
+      }
+
+  /* Final attempt: try a forward lookup of the helo name */
+
+  if (!f.helo_verified)
+    {
+    int rc;
+    host_item h =
+      {.name = sender_helo_name, .address = NULL, .mx = MX_NONE, .next = NULL};
+    dnssec_domains d =
+      {.request = US"*", .require = US""};
+
+    HDEBUG(D_receive) debug_printf("getting IP address for %s\n",
+      sender_helo_name);
+    rc = host_find_bydns(&h, NULL, HOST_FIND_BY_A | HOST_FIND_BY_AAAA,
+			  NULL, NULL, NULL, &d, NULL, NULL);
+    if (rc == HOST_FOUND || rc == HOST_FOUND_LOCAL)
+      for (host_item * hh = &h; hh; hh = hh->next)
+        if (Ustrcmp(hh->address, sender_host_address) == 0)
+          {
+          f.helo_verified = TRUE;
+	  if (h.dnssec == DS_YES) sender_helo_dnssec = TRUE;
+          HDEBUG(D_receive)
+            debug_printf("IP address for %s matches calling address\n"
+	      "Forward DNS security status: %sverified\n",
+              sender_helo_name, sender_helo_dnssec ? "" : "un");
+          break;
+          }
+    }
+  }
+
+if (!f.helo_verified) f.helo_verify_failed = TRUE;  /* We've tried ... */
+return yield;
+}
+
+
+
+
+/*************************************************
+*        Send user response message              *
+*************************************************/
+
+/* This function is passed a default response code and a user message. It calls
+smtp_message_code() to check and possibly modify the response code, and then
+calls smtp_respond() to transmit the response. I put this into a function
+just to avoid a lot of repetition.
+
+Arguments:
+  code         the response code
+  user_msg     the user message
+
+Returns:       nothing
+*/
+
+static void
+smtp_user_msg(uschar *code, uschar *user_msg)
+{
+int len = 3;
+smtp_message_code(&code, &len, &user_msg, NULL, TRUE);
+smtp_respond(code, len, TRUE, user_msg);
+}
+
+
+
+static int
+smtp_in_auth(auth_instance *au, uschar ** s, uschar ** ss)
+{
+const uschar *set_id = NULL;
+int rc;
+
+/* Set up globals for error messages */
+
+authenticator_name = au->name;
+driver_srcfile = au->srcfile;
+driver_srcline = au->srcline;
+
+/* Run the checking code, passing the remainder of the command line as
+data. Initials the $auth<n> variables as empty. Initialize $0 empty and set
+it as the only set numerical variable. The authenticator may set $auth<n>
+and also set other numeric variables. The $auth<n> variables are preferred
+nowadays; the numerical variables remain for backwards compatibility.
+
+Afterwards, have a go at expanding the set_id string, even if
+authentication failed - for bad passwords it can be useful to log the
+userid. On success, require set_id to expand and exist, and put it in
+authenticated_id. Save this in permanent store, as the working store gets
+reset at HELO, RSET, etc. */
+
+for (int i = 0; i < AUTH_VARS; i++) auth_vars[i] = NULL;
+expand_nmax = 0;
+expand_nlength[0] = 0;   /* $0 contains nothing */
+
+rc = (au->info->servercode)(au, smtp_cmd_data);
+if (au->set_id) set_id = expand_string(au->set_id);
+expand_nmax = -1;        /* Reset numeric variables */
+for (int i = 0; i < AUTH_VARS; i++) auth_vars[i] = NULL;   /* Reset $auth<n> */
+driver_srcfile = authenticator_name = NULL; driver_srcline = 0;
+
+/* The value of authenticated_id is stored in the spool file and printed in
+log lines. It must not contain binary zeros or newline characters. In
+normal use, it never will, but when playing around or testing, this error
+can (did) happen. To guard against this, ensure that the id contains only
+printing characters. */
+
+if (set_id) set_id = string_printing(set_id);
+
+/* For the non-OK cases, set up additional logging data if set_id
+is not empty. */
+
+if (rc != OK)
+  set_id = set_id && *set_id
+    ? string_sprintf(" (set_id=%s)", set_id) : US"";
+
+/* Switch on the result */
+
+switch(rc)
+  {
+  case OK:
+    if (!au->set_id || set_id)    /* Complete success */
+      {
+      if (set_id) authenticated_id = string_copy_perm(set_id, TRUE);
+      sender_host_authenticated = au->name;
+      sender_host_auth_pubname  = au->public_name;
+      authentication_failed = FALSE;
+      authenticated_fail_id = NULL;   /* Impossible to already be set? */
+
+      received_protocol =
+	(sender_host_address ? protocols : protocols_local)
+	  [pextend + pauthed + (tls_in.active.sock >= 0 ? pcrpted:0)];
+      *s = *ss = US"235 Authentication succeeded";
+      authenticated_by = au;
+      break;
+      }
+
+    /* Authentication succeeded, but we failed to expand the set_id string.
+    Treat this as a temporary error. */
+
+    auth_defer_msg = expand_string_message;
+    /* Fall through */
+
+  case DEFER:
+    if (set_id) authenticated_fail_id = string_copy_perm(set_id, TRUE);
+    *s = string_sprintf("435 Unable to authenticate at present%s",
+      auth_defer_user_msg);
+    *ss = string_sprintf("435 Unable to authenticate at present%s: %s",
+      set_id, auth_defer_msg);
+    break;
+
+  case BAD64:
+    *s = *ss = US"501 Invalid base64 data";
+    break;
+
+  case CANCELLED:
+    *s = *ss = US"501 Authentication cancelled";
+    break;
+
+  case UNEXPECTED:
+    *s = *ss = US"553 Initial data not expected";
+    break;
+
+  case FAIL:
+    if (set_id) authenticated_fail_id = string_copy_perm(set_id, TRUE);
+    *s = US"535 Incorrect authentication data";
+    *ss = string_sprintf("535 Incorrect authentication data%s", set_id);
+    break;
+
+  default:
+    if (set_id) authenticated_fail_id = string_copy_perm(set_id, TRUE);
+    *s = US"435 Internal error";
+    *ss = string_sprintf("435 Internal error%s: return %d from authentication "
+      "check", set_id, rc);
+    break;
+  }
+
+return rc;
+}
+
+
+
+
+
+static int
+qualify_recipient(uschar ** recipient, uschar * smtp_cmd_data, uschar * tag)
+{
+int rd;
+if (f.allow_unqualified_recipient || strcmpic(*recipient, US"postmaster") == 0)
+  {
+  DEBUG(D_receive) debug_printf("unqualified address %s accepted\n",
+    *recipient);
+  rd = Ustrlen(recipient) + 1;
+  /* deconst ok as *recipient was not const */
+  *recipient = US rewrite_address_qualify(*recipient, TRUE);
+  return rd;
+  }
+smtp_printf("501 %s: recipient address must contain a domain\r\n", FALSE,
+  smtp_cmd_data);
+log_write(L_smtp_syntax_error,
+  LOG_MAIN|LOG_REJECT, "unqualified %s rejected: <%s> %s%s",
+  tag, *recipient, host_and_ident(TRUE), host_lookup_msg);
+return 0;
+}
+
+
+
+
+static void
+smtp_quit_handler(uschar ** user_msgp, uschar ** log_msgp)
+{
+HAD(SCH_QUIT);
+f.smtp_in_quit = TRUE;
+incomplete_transaction_log(US"QUIT");
+if (  acl_smtp_quit
+   && acl_check(ACL_WHERE_QUIT, NULL, acl_smtp_quit, user_msgp, log_msgp)
+	== ERROR)
+    log_write(0, LOG_MAIN|LOG_PANIC, "ACL for QUIT returned ERROR: %s",
+      *log_msgp);
+
+#ifdef EXIM_TCP_CORK
+(void) setsockopt(fileno(smtp_out), IPPROTO_TCP, EXIM_TCP_CORK, US &on, sizeof(on));
+#endif
+
+if (*user_msgp)
+  smtp_respond(US"221", 3, TRUE, *user_msgp);
+else
+  smtp_printf("221 %s closing connection\r\n", FALSE, smtp_active_hostname);
+
+#ifdef SERVERSIDE_CLOSE_NOWAIT
+# ifndef DISABLE_TLS
+tls_close(NULL, TLS_SHUTDOWN_NOWAIT);
+# endif
+
+log_write(L_smtp_connection, LOG_MAIN, "%s closed by QUIT",
+  smtp_get_connection_info());
+#else
+
+# ifndef DISABLE_TLS
+tls_close(NULL, TLS_SHUTDOWN_WAIT);
+# endif
+
+log_write(L_smtp_connection, LOG_MAIN, "%s closed by QUIT",
+  smtp_get_connection_info());
+
+/* Pause, hoping client will FIN first so that they get the TIME_WAIT.
+The socket should become readble (though with no data) */
+
+(void) poll_one_fd(fileno(smtp_in), POLLIN, 200);
+#endif	/*!SERVERSIDE_CLOSE_NOWAIT*/
+}
+
+
+static void
+smtp_rset_handler(void)
+{
+HAD(SCH_RSET);
+incomplete_transaction_log(US"RSET");
+smtp_printf("250 Reset OK\r\n", FALSE);
+cmd_list[CMD_LIST_RSET].is_mail_cmd = FALSE;
+if (chunking_state > CHUNKING_OFFERED)
+  chunking_state = CHUNKING_OFFERED;
+}
+
+
+static int
+expand_mailmax(const uschar * s)
+{
+if (!(s = expand_cstring(s)))
+  log_write(0, LOG_MAIN|LOG_PANIC, "failed to expand smtp_accept_max_per_connection");
+return *s ? Uatoi(s) : 0;
+}
+
+/*************************************************
+*       Initialize for SMTP incoming message     *
+*************************************************/
+
+/* This function conducts the initial dialogue at the start of an incoming SMTP
+message, and builds a list of recipients. However, if the incoming message
+is part of a batch (-bS option) a separate function is called since it would
+be messy having tests splattered about all over this function. This function
+therefore handles the case where interaction is occurring. The input and output
+files are set up in smtp_in and smtp_out.
+
+The global recipients_list is set to point to a vector of recipient_item
+blocks, whose number is given by recipients_count. This is extended by the
+receive_add_recipient() function. The global variable sender_address is set to
+the sender's address. The yield is +1 if a message has been successfully
+started, 0 if a QUIT command was encountered or the connection was refused from
+the particular host, or -1 if the connection was lost.
+
+Argument: none
+
+Returns:  > 0 message successfully started (reached DATA)
+          = 0 QUIT read or end of file reached or call refused
+          < 0 lost connection
+*/
+
+int
+smtp_setup_msg(void)
+{
+int done = 0;
+BOOL toomany = FALSE;
+BOOL discarded = FALSE;
+BOOL last_was_rej_mail = FALSE;
+BOOL last_was_rcpt = FALSE;
+rmark reset_point = store_mark();
+
+DEBUG(D_receive) debug_printf("smtp_setup_msg entered\n");
+
+/* Reset for start of new message. We allow one RSET not to be counted as a
+nonmail command, for those MTAs that insist on sending it between every
+message. Ditto for EHLO/HELO and for STARTTLS, to allow for going in and out of
+TLS between messages (an Exim client may do this if it has messages queued up
+for the host). Note: we do NOT reset AUTH at this point. */
+
+reset_point = smtp_reset(reset_point);
+message_ended = END_NOTSTARTED;
+
+chunking_state = f.chunking_offered ? CHUNKING_OFFERED : CHUNKING_NOT_OFFERED;
+
+cmd_list[CMD_LIST_RSET].is_mail_cmd = TRUE;
+cmd_list[CMD_LIST_HELO].is_mail_cmd = TRUE;
+cmd_list[CMD_LIST_EHLO].is_mail_cmd = TRUE;
+#ifndef DISABLE_TLS
+cmd_list[CMD_LIST_STARTTLS].is_mail_cmd = TRUE;
+#endif
+
+if (lwr_receive_getc != NULL)
+  {
+  /* This should have already happened, but if we've gotten confused,
+  force a reset here. */
+  DEBUG(D_receive) debug_printf("WARNING: smtp_setup_msg had to restore receive functions to lowers\n");
+  bdat_pop_receive_functions();
+  }
+
+/* Set the local signal handler for SIGTERM - it tries to end off tidily */
+
+had_command_sigterm = 0;
+os_non_restarting_signal(SIGTERM, command_sigterm_handler);
+
+/* Batched SMTP is handled in a different function. */
+
+if (smtp_batched_input) return smtp_setup_batch_msg();
+
+#ifdef TCP_QUICKACK
+if (smtp_in)		/* Avoid pure-ACKs while in cmd pingpong phase */
+  (void) setsockopt(fileno(smtp_in), IPPROTO_TCP, TCP_QUICKACK,
+	  US &off, sizeof(off));
+#endif
+
+/* Deal with SMTP commands. This loop is exited by setting done to a POSITIVE
+value. The values are 2 larger than the required yield of the function. */
+
+while (done <= 0)
+  {
+  const uschar **argv;
+  uschar *etrn_command;
+  uschar *etrn_serialize_key;
+  uschar *errmess;
+  uschar *log_msg, *smtp_code;
+  uschar *user_msg = NULL;
+  uschar *recipient = NULL;
+  uschar *hello = NULL;
+  uschar *s, *ss;
+  BOOL was_rej_mail = FALSE;
+  BOOL was_rcpt = FALSE;
+  void (*oldsignal)(int);
+  pid_t pid;
+  int start, end, sender_domain, recipient_domain;
+  int rc;
+  int c;
+  uschar *orcpt = NULL;
+  int dsn_flags;
+  gstring * g;
+
+#ifdef AUTH_TLS
+  /* Check once per STARTTLS or SSL-on-connect for a TLS AUTH */
+  if (  tls_in.active.sock >= 0
+     && tls_in.peercert
+     && tls_in.certificate_verified
+     && cmd_list[CMD_LIST_TLS_AUTH].is_mail_cmd
+     )
+    {
+    cmd_list[CMD_LIST_TLS_AUTH].is_mail_cmd = FALSE;
+
+    for (auth_instance * au = auths; au; au = au->next)
+      if (strcmpic(US"tls", au->driver_name) == 0)
+	{
+	if (  acl_smtp_auth
+	   && (rc = acl_check(ACL_WHERE_AUTH, NULL, acl_smtp_auth,
+		      &user_msg, &log_msg)) != OK
+	   )
+	  done = smtp_handle_acl_fail(ACL_WHERE_AUTH, rc, user_msg, log_msg);
+	else
+	  {
+	  smtp_cmd_data = NULL;
+
+	  if (smtp_in_auth(au, &s, &ss) == OK)
+	    { DEBUG(D_auth) debug_printf("tls auth succeeded\n"); }
+	  else
+	    { DEBUG(D_auth) debug_printf("tls auth not succeeded\n"); }
+	  }
+	break;
+	}
+    }
+#endif
+
+  switch(smtp_read_command(
+#ifndef DISABLE_PIPE_CONNECT
+	  !fl.pipe_connect_acceptable,
+#else
+	  TRUE,
+#endif
+	  GETC_BUFFER_UNLIMITED))
+    {
+    /* The AUTH command is not permitted to occur inside a transaction, and may
+    occur successfully only once per connection. Actually, that isn't quite
+    true. When TLS is started, all previous information about a connection must
+    be discarded, so a new AUTH is permitted at that time.
+
+    AUTH may only be used when it has been advertised. However, it seems that
+    there are clients that send AUTH when it hasn't been advertised, some of
+    them even doing this after HELO. And there are MTAs that accept this. Sigh.
+    So there's a get-out that allows this to happen.
+
+    AUTH is initially labelled as a "nonmail command" so that one occurrence
+    doesn't get counted. We change the label here so that multiple failing
+    AUTHS will eventually hit the nonmail threshold. */
+
+    case AUTH_CMD:
+      HAD(SCH_AUTH);
+      authentication_failed = TRUE;
+      cmd_list[CMD_LIST_AUTH].is_mail_cmd = FALSE;
+
+      if (!fl.auth_advertised && !f.allow_auth_unadvertised)
+	{
+	done = synprot_error(L_smtp_protocol_error, 503, NULL,
+	  US"AUTH command used when not advertised");
+	break;
+	}
+      if (sender_host_authenticated)
+	{
+	done = synprot_error(L_smtp_protocol_error, 503, NULL,
+	  US"already authenticated");
+	break;
+	}
+      if (sender_address)
+	{
+	done = synprot_error(L_smtp_protocol_error, 503, NULL,
+	  US"not permitted in mail transaction");
+	break;
+	}
+
+      /* Check the ACL */
+
+      if (  acl_smtp_auth
+	 && (rc = acl_check(ACL_WHERE_AUTH, NULL, acl_smtp_auth,
+		    &user_msg, &log_msg)) != OK
+	 )
+	{
+	done = smtp_handle_acl_fail(ACL_WHERE_AUTH, rc, user_msg, log_msg);
+	break;
+	}
+
+      /* Find the name of the requested authentication mechanism. */
+
+      s = smtp_cmd_data;
+      for (; (c = *smtp_cmd_data) && !isspace(c); smtp_cmd_data++)
+	if (!isalnum(c) && c != '-' && c != '_')
+	  {
+	  done = synprot_error(L_smtp_syntax_error, 501, NULL,
+	    US"invalid character in authentication mechanism name");
+	  goto COMMAND_LOOP;
+	  }
+
+      /* If not at the end of the line, we must be at white space. Terminate the
+      name and move the pointer on to any data that may be present. */
+
+      if (*smtp_cmd_data)
+	{
+	*smtp_cmd_data++ = 0;
+	while (isspace(*smtp_cmd_data)) smtp_cmd_data++;
+	}
+
+      /* Search for an authentication mechanism which is configured for use
+      as a server and which has been advertised (unless, sigh, allow_auth_
+      unadvertised is set). */
+
+	{
+	auth_instance * au;
+	for (au = auths; au; au = au->next)
+	  if (strcmpic(s, au->public_name) == 0 && au->server &&
+	      (au->advertised || f.allow_auth_unadvertised))
+	    break;
+
+	if (au)
+	  {
+	  c = smtp_in_auth(au, &s, &ss);
+
+	  smtp_printf("%s\r\n", FALSE, s);
+	  if (c != OK)
+	    log_write(0, LOG_MAIN|LOG_REJECT, "%s authenticator failed for %s: %s",
+	      au->name, host_and_ident(FALSE), ss);
+	  }
+	else
+	  done = synprot_error(L_smtp_protocol_error, 504, NULL,
+	    string_sprintf("%s authentication mechanism not supported", s));
+	}
+
+      break;  /* AUTH_CMD */
+
+    /* The HELO/EHLO commands are permitted to appear in the middle of a
+    session as well as at the beginning. They have the effect of a reset in
+    addition to their other functions. Their absence at the start cannot be
+    taken to be an error.
+
+    RFC 2821 says:
+
+      If the EHLO command is not acceptable to the SMTP server, 501, 500,
+      or 502 failure replies MUST be returned as appropriate.  The SMTP
+      server MUST stay in the same state after transmitting these replies
+      that it was in before the EHLO was received.
+
+    Therefore, we do not do the reset until after checking the command for
+    acceptability. This change was made for Exim release 4.11. Previously
+    it did the reset first. */
+
+    case HELO_CMD:
+      HAD(SCH_HELO);
+      hello = US"HELO";
+      fl.esmtp = FALSE;
+      goto HELO_EHLO;
+
+    case EHLO_CMD:
+      HAD(SCH_EHLO);
+      hello = US"EHLO";
+      fl.esmtp = TRUE;
+
+    HELO_EHLO:      /* Common code for HELO and EHLO */
+      cmd_list[CMD_LIST_HELO].is_mail_cmd = FALSE;
+      cmd_list[CMD_LIST_EHLO].is_mail_cmd = FALSE;
+
+      /* Reject the HELO if its argument was invalid or non-existent. A
+      successful check causes the argument to be saved in malloc store. */
+
+      if (!check_helo(smtp_cmd_data))
+	{
+	smtp_printf("501 Syntactically invalid %s argument(s)\r\n", FALSE, hello);
+
+	log_write(0, LOG_MAIN|LOG_REJECT, "rejected %s from %s: syntactically "
+	  "invalid argument(s): %s", hello, host_and_ident(FALSE),
+	  *smtp_cmd_argument == 0 ? US"(no argument given)" :
+			     string_printing(smtp_cmd_argument));
+
+	if (++synprot_error_count > smtp_max_synprot_errors)
+	  {
+	  log_write(0, LOG_MAIN|LOG_REJECT, "SMTP call from %s dropped: too many "
+	    "syntax or protocol errors (last command was \"%s\", %s)",
+	    host_and_ident(FALSE), string_printing(smtp_cmd_buffer),
+	    string_from_gstring(s_connhad_log(NULL))
+	    );
+	  done = 1;
+	  }
+
+	break;
+	}
+
+      /* If sender_host_unknown is true, we have got here via the -bs interface,
+      not called from inetd. Otherwise, we are running an IP connection and the
+      host address will be set. If the helo name is the primary name of this
+      host and we haven't done a reverse lookup, force one now. If helo_verify_required
+      is set, ensure that the HELO name matches the actual host. If helo_verify
+      is set, do the same check, but softly. */
+
+      if (!f.sender_host_unknown)
+	{
+	BOOL old_helo_verified = f.helo_verified;
+	uschar *p = smtp_cmd_data;
+
+	while (*p != 0 && !isspace(*p)) { *p = tolower(*p); p++; }
+	*p = 0;
+
+	/* Force a reverse lookup if HELO quoted something in helo_lookup_domains
+	because otherwise the log can be confusing. */
+
+	if (  !sender_host_name
+	   && match_isinlist(sender_helo_name, CUSS &helo_lookup_domains, 0,
+		&domainlist_anchor, NULL, MCL_DOMAIN, TRUE, NULL) == OK)
+	  (void)host_name_lookup();
+
+	/* Rebuild the fullhost info to include the HELO name (and the real name
+	if it was looked up.) */
+
+	host_build_sender_fullhost();  /* Rebuild */
+	set_process_info("handling%s incoming connection from %s",
+	  tls_in.active.sock >= 0 ? " TLS" : "", host_and_ident(FALSE));
+
+	/* Verify if configured. This doesn't give much security, but it does
+	make some people happy to be able to do it. If helo_verify_required is set,
+	(host matches helo_verify_hosts) failure forces rejection. If helo_verify
+	is set (host matches helo_try_verify_hosts), it does not. This is perhaps
+	now obsolescent, since the verification can now be requested selectively
+	at ACL time. */
+
+	f.helo_verified = f.helo_verify_failed = sender_helo_dnssec = FALSE;
+	if (fl.helo_verify_required || fl.helo_verify)
+	  {
+	  BOOL tempfail = !smtp_verify_helo();
+	  if (!f.helo_verified)
+	    {
+	    if (fl.helo_verify_required)
+	      {
+	      smtp_printf("%d %s argument does not match calling host\r\n", FALSE,
+		tempfail? 451 : 550, hello);
+	      log_write(0, LOG_MAIN|LOG_REJECT, "%srejected \"%s %s\" from %s",
+		tempfail? "temporarily " : "",
+		hello, sender_helo_name, host_and_ident(FALSE));
+	      f.helo_verified = old_helo_verified;
+	      break;                   /* End of HELO/EHLO processing */
+	      }
+	    HDEBUG(D_all) debug_printf("%s verification failed but host is in "
+	      "helo_try_verify_hosts\n", hello);
+	    }
+	  }
+	}
+
+#ifdef SUPPORT_SPF
+      /* set up SPF context */
+      spf_conn_init(sender_helo_name, sender_host_address);
+#endif
+
+      /* Apply an ACL check if one is defined; afterwards, recheck
+      synchronization in case the client started sending in a delay. */
+
+      if (acl_smtp_helo)
+	if ((rc = acl_check(ACL_WHERE_HELO, NULL, acl_smtp_helo,
+		  &user_msg, &log_msg)) != OK)
+	  {
+	  done = smtp_handle_acl_fail(ACL_WHERE_HELO, rc, user_msg, log_msg);
+	  sender_helo_name = NULL;
+	  host_build_sender_fullhost();  /* Rebuild */
+	  break;
+	  }
+#ifndef DISABLE_PIPE_CONNECT
+	else if (!fl.pipe_connect_acceptable && !check_sync())
+#else
+	else if (!check_sync())
+#endif
+	  goto SYNC_FAILURE;
+
+      /* Generate an OK reply. The default string includes the ident if present,
+      and also the IP address if present. Reflecting back the ident is intended
+      as a deterrent to mail forgers. For maximum efficiency, and also because
+      some broken systems expect each response to be in a single packet, arrange
+      that the entire reply is sent in one write(). */
+
+      fl.auth_advertised = FALSE;
+      f.smtp_in_pipelining_advertised = FALSE;
+#ifndef DISABLE_TLS
+      fl.tls_advertised = FALSE;
+#endif
+      fl.dsn_advertised = FALSE;
+#ifdef SUPPORT_I18N
+      fl.smtputf8_advertised = FALSE;
+#endif
+
+      /* Expand the per-connection message count limit option */
+      smtp_mailcmd_max = expand_mailmax(smtp_accept_max_per_connection);
+
+      smtp_code = US"250 ";        /* Default response code plus space*/
+      if (!user_msg)
+	{
+	/* sender_host_name below will be tainted, so save on copy when we hit it */
+	g = string_get_tainted(24, GET_TAINTED);
+	g = string_fmt_append(g, "%.3s %s Hello %s%s%s",
+	  smtp_code,
+	  smtp_active_hostname,
+	  sender_ident ? sender_ident : US"",
+	  sender_ident ? US" at " : US"",
+	  sender_host_name ? sender_host_name : sender_helo_name);
+
+	if (sender_host_address)
+	  g = string_fmt_append(g, " [%s]", sender_host_address);
+	}
+
+      /* A user-supplied EHLO greeting may not contain more than one line. Note
+      that the code returned by smtp_message_code() includes the terminating
+      whitespace character. */
+
+      else
+	{
+	char *ss;
+	int codelen = 4;
+	smtp_message_code(&smtp_code, &codelen, &user_msg, NULL, TRUE);
+	s = string_sprintf("%.*s%s", codelen, smtp_code, user_msg);
+	if ((ss = strpbrk(CS s, "\r\n")) != NULL)
+	  {
+	  log_write(0, LOG_MAIN|LOG_PANIC, "EHLO/HELO response must not contain "
+	    "newlines: message truncated: %s", string_printing(s));
+	  *ss = 0;
+	  }
+	g = string_cat(NULL, s);
+	}
+
+      g = string_catn(g, US"\r\n", 2);
+
+      /* If we received EHLO, we must create a multiline response which includes
+      the functions supported. */
+
+      if (fl.esmtp)
+	{
+	g->s[3] = '-';
+
+	/* I'm not entirely happy with this, as an MTA is supposed to check
+	that it has enough room to accept a message of maximum size before
+	it sends this. However, there seems little point in not sending it.
+	The actual size check happens later at MAIL FROM time. By postponing it
+	till then, VRFY and EXPN can be used after EHLO when space is short. */
+
+	if (thismessage_size_limit > 0)
+	  g = string_fmt_append(g, "%.3s-SIZE %d\r\n", smtp_code,
+	    thismessage_size_limit);
+	else
+	  {
+	  g = string_catn(g, smtp_code, 3);
+	  g = string_catn(g, US"-SIZE\r\n", 7);
+	  }
+
+#ifdef EXPERIMENTAL_ESMTP_LIMITS
+	if (  (smtp_mailcmd_max > 0 || recipients_max)
+	   && verify_check_host(&limits_advertise_hosts) == OK)
+	  {
+	  g = string_fmt_append(g, "%.3s-LIMITS", smtp_code);
+	  if (smtp_mailcmd_max > 0)
+	    g = string_fmt_append(g, " MAILMAX=%d", smtp_mailcmd_max);
+	  if (recipients_max)
+	    g = string_fmt_append(g, " RCPTMAX=%d", recipients_max);
+	  g = string_catn(g, US"\r\n", 2);
+	  }
+#endif
+
+	/* Exim does not do protocol conversion or data conversion. It is 8-bit
+	clean; if it has an 8-bit character in its hand, it just sends it. It
+	cannot therefore specify 8BITMIME and remain consistent with the RFCs.
+	However, some users want this option simply in order to stop MUAs
+	mangling messages that contain top-bit-set characters. It is therefore
+	provided as an option. */
+
+	if (accept_8bitmime)
+	  {
+	  g = string_catn(g, smtp_code, 3);
+	  g = string_catn(g, US"-8BITMIME\r\n", 11);
+	  }
+
+	/* Advertise DSN support if configured to do so. */
+	if (verify_check_host(&dsn_advertise_hosts) != FAIL)
+	  {
+	  g = string_catn(g, smtp_code, 3);
+	  g = string_catn(g, US"-DSN\r\n", 6);
+	  fl.dsn_advertised = TRUE;
+	  }
+
+	/* Advertise ETRN/VRFY/EXPN if there's are ACL checking whether a host is
+	permitted to issue them; a check is made when any host actually tries. */
+
+	if (acl_smtp_etrn)
+	  {
+	  g = string_catn(g, smtp_code, 3);
+	  g = string_catn(g, US"-ETRN\r\n", 7);
+	  }
+	if (acl_smtp_vrfy)
+	  {
+	  g = string_catn(g, smtp_code, 3);
+	  g = string_catn(g, US"-VRFY\r\n", 7);
+	  }
+	if (acl_smtp_expn)
+	  {
+	  g = string_catn(g, smtp_code, 3);
+	  g = string_catn(g, US"-EXPN\r\n", 7);
+	  }
+
+	/* Exim is quite happy with pipelining, so let the other end know that
+	it is safe to use it, unless advertising is disabled. */
+
+	if (  f.pipelining_enable
+	   && verify_check_host(&pipelining_advertise_hosts) == OK)
+	  {
+	  g = string_catn(g, smtp_code, 3);
+	  g = string_catn(g, US"-PIPELINING\r\n", 13);
+	  sync_cmd_limit = NON_SYNC_CMD_PIPELINING;
+	  f.smtp_in_pipelining_advertised = TRUE;
+
+#ifndef DISABLE_PIPE_CONNECT
+	  if (fl.pipe_connect_acceptable)
+	    {
+	    f.smtp_in_early_pipe_advertised = TRUE;
+	    g = string_catn(g, smtp_code, 3);
+	    g = string_catn(g, US"-" EARLY_PIPE_FEATURE_NAME "\r\n", EARLY_PIPE_FEATURE_LEN+3);
+	    }
+#endif
+	  }
+
+
+	/* If any server authentication mechanisms are configured, advertise
+	them if the current host is in auth_advertise_hosts. The problem with
+	advertising always is that some clients then require users to
+	authenticate (and aren't configurable otherwise) even though it may not
+	be necessary (e.g. if the host is in host_accept_relay).
+
+	RFC 2222 states that SASL mechanism names contain only upper case
+	letters, so output the names in upper case, though we actually recognize
+	them in either case in the AUTH command. */
+
+	if (  auths
+#ifdef AUTH_TLS
+	   && !sender_host_authenticated
+#endif
+	   && verify_check_host(&auth_advertise_hosts) == OK
+	   )
+	  {
+	  BOOL first = TRUE;
+	  for (auth_instance * au = auths; au; au = au->next)
+	    {
+	    au->advertised = FALSE;
+	    if (au->server)
+	      {
+	      DEBUG(D_auth+D_expand) debug_printf_indent(
+		"Evaluating advertise_condition for %s %s athenticator\n",
+		au->name, au->public_name);
+	      if (  !au->advertise_condition
+		 || expand_check_condition(au->advertise_condition, au->name,
+			US"authenticator")
+		 )
+		{
+		int saveptr;
+		if (first)
+		  {
+		  g = string_catn(g, smtp_code, 3);
+		  g = string_catn(g, US"-AUTH", 5);
+		  first = FALSE;
+		  fl.auth_advertised = TRUE;
+		  }
+		saveptr = g->ptr;
+		g = string_catn(g, US" ", 1);
+		g = string_cat (g, au->public_name);
+		while (++saveptr < g->ptr) g->s[saveptr] = toupper(g->s[saveptr]);
+		au->advertised = TRUE;
+		}
+	      }
+	    }
+
+	  if (!first) g = string_catn(g, US"\r\n", 2);
+	  }
+
+	/* RFC 3030 CHUNKING */
+
+	if (verify_check_host(&chunking_advertise_hosts) != FAIL)
+	  {
+	  g = string_catn(g, smtp_code, 3);
+	  g = string_catn(g, US"-CHUNKING\r\n", 11);
+	  f.chunking_offered = TRUE;
+	  chunking_state = CHUNKING_OFFERED;
+	  }
+
+	/* Advertise TLS (Transport Level Security) aka SSL (Secure Socket Layer)
+	if it has been included in the binary, and the host matches
+	tls_advertise_hosts. We must *not* advertise if we are already in a
+	secure connection. */
+
+#ifndef DISABLE_TLS
+	if (tls_in.active.sock < 0 &&
+	    verify_check_host(&tls_advertise_hosts) != FAIL)
+	  {
+	  g = string_catn(g, smtp_code, 3);
+	  g = string_catn(g, US"-STARTTLS\r\n", 11);
+	  fl.tls_advertised = TRUE;
+	  }
+#endif
+
+#ifndef DISABLE_PRDR
+	/* Per Recipient Data Response, draft by Eric A. Hall extending RFC */
+	if (prdr_enable)
+	  {
+	  g = string_catn(g, smtp_code, 3);
+	  g = string_catn(g, US"-PRDR\r\n", 7);
+	  }
+#endif
+
+#ifdef SUPPORT_I18N
+	if (  accept_8bitmime
+	   && verify_check_host(&smtputf8_advertise_hosts) != FAIL)
+	  {
+	  g = string_catn(g, smtp_code, 3);
+	  g = string_catn(g, US"-SMTPUTF8\r\n", 11);
+	  fl.smtputf8_advertised = TRUE;
+	  }
+#endif
+
+	/* Finish off the multiline reply with one that is always available. */
+
+	g = string_catn(g, smtp_code, 3);
+	g = string_catn(g, US" HELP\r\n", 7);
+	}
+
+      /* Terminate the string (for debug), write it, and note that HELO/EHLO
+      has been seen. */
+
+#ifndef DISABLE_TLS
+      if (tls_in.active.sock >= 0)
+	(void)tls_write(NULL, g->s, g->ptr,
+# ifndef DISABLE_PIPE_CONNECT
+			fl.pipe_connect_acceptable && pipeline_connect_sends());
+# else
+			FALSE);
+# endif
+      else
+#endif
+	(void) fwrite(g->s, 1, g->ptr, smtp_out);
+
+      DEBUG(D_receive) for (const uschar * t, * s = string_from_gstring(g);
+			    s && (t = Ustrchr(s, '\r'));
+			    s = t + 2)				/* \r\n */
+	  debug_printf("%s %.*s\n",
+			s == g->s ? "SMTP>>" : "      ",
+			(int)(t - s), s);
+      fl.helo_seen = TRUE;
+
+      /* Reset the protocol and the state, abandoning any previous message. */
+      received_protocol =
+	(sender_host_address ? protocols : protocols_local)
+	  [ (fl.esmtp
+	    ? pextend + (sender_host_authenticated ? pauthed : 0)
+	    : pnormal)
+	  + (tls_in.active.sock >= 0 ? pcrpted : 0)
+	  ];
+      cancel_cutthrough_connection(TRUE, US"sent EHLO response");
+      reset_point = smtp_reset(reset_point);
+      toomany = FALSE;
+      break;   /* HELO/EHLO */
+
+
+    /* The MAIL command requires an address as an operand. All we do
+    here is to parse it for syntactic correctness. The form "<>" is
+    a special case which converts into an empty string. The start/end
+    pointers in the original are not used further for this address, as
+    it is the canonical extracted address which is all that is kept. */
+
+    case MAIL_CMD:
+      HAD(SCH_MAIL);
+      smtp_mailcmd_count++;              /* Count for limit and ratelimit */
+      message_start();
+      was_rej_mail = TRUE;               /* Reset if accepted */
+      env_mail_type_t * mail_args;       /* Sanity check & validate args */
+
+      if (!fl.helo_seen)
+	if (  fl.helo_verify_required
+	   || verify_check_host(&hosts_require_helo) == OK)
+	  {
+	  smtp_printf("503 HELO or EHLO required\r\n", FALSE);
+	  log_write(0, LOG_MAIN|LOG_REJECT, "rejected MAIL from %s: no "
+	    "HELO/EHLO given", host_and_ident(FALSE));
+	  break;
+	  }
+	else if (smtp_mailcmd_max < 0)
+	  smtp_mailcmd_max = expand_mailmax(smtp_accept_max_per_connection);
+
+      if (sender_address)
+	{
+	done = synprot_error(L_smtp_protocol_error, 503, NULL,
+	  US"sender already given");
+	break;
+	}
+
+      if (!*smtp_cmd_data)
+	{
+	done = synprot_error(L_smtp_protocol_error, 501, NULL,
+	  US"MAIL must have an address operand");
+	break;
+	}
+
+      /* Check to see if the limit for messages per connection would be
+      exceeded by accepting further messages. */
+
+      if (smtp_mailcmd_max > 0 && smtp_mailcmd_count > smtp_mailcmd_max)
+	{
+	smtp_printf("421 too many messages in this connection\r\n", FALSE);
+	log_write(0, LOG_MAIN|LOG_REJECT, "rejected MAIL command %s: too many "
+	  "messages in one connection", host_and_ident(TRUE));
+	break;
+	}
+
+      /* Reset for start of message - even if this is going to fail, we
+      obviously need to throw away any previous data. */
+
+      cancel_cutthrough_connection(TRUE, US"MAIL received");
+      reset_point = smtp_reset(reset_point);
+      toomany = FALSE;
+      sender_data = recipient_data = NULL;
+
+      /* Loop, checking for ESMTP additions to the MAIL FROM command. */
+
+      if (fl.esmtp) for(;;)
+	{
+	uschar *name, *value, *end;
+	unsigned long int size;
+	BOOL arg_error = FALSE;
+
+	if (!extract_option(&name, &value)) break;
+
+	for (mail_args = env_mail_type_list;
+	     mail_args->value != ENV_MAIL_OPT_NULL;
+	     mail_args++
+	    )
+	  if (strcmpic(name, mail_args->name) == 0)
+	    break;
+	if (mail_args->need_value && strcmpic(value, US"") == 0)
+	  break;
+
+	switch(mail_args->value)
+	  {
+	  /* Handle SIZE= by reading the value. We don't do the check till later,
+	  in order to be able to log the sender address on failure. */
+	  case ENV_MAIL_OPT_SIZE:
+	    if (((size = Ustrtoul(value, &end, 10)), *end == 0))
+	      {
+	      if ((size == ULONG_MAX && errno == ERANGE) || size > INT_MAX)
+		size = INT_MAX;
+	      message_size = (int)size;
+	      }
+	    else
+	      arg_error = TRUE;
+	    break;
+
+	  /* If this session was initiated with EHLO and accept_8bitmime is set,
+	  Exim will have indicated that it supports the BODY=8BITMIME option. In
+	  fact, it does not support this according to the RFCs, in that it does not
+	  take any special action for forwarding messages containing 8-bit
+	  characters. That is why accept_8bitmime is not the default setting, but
+	  some sites want the action that is provided. We recognize both "8BITMIME"
+	  and "7BIT" as body types, but take no action. */
+	  case ENV_MAIL_OPT_BODY:
+	    if (accept_8bitmime) {
+	      if (strcmpic(value, US"8BITMIME") == 0)
+		body_8bitmime = 8;
+	      else if (strcmpic(value, US"7BIT") == 0)
+		body_8bitmime = 7;
+	      else
+		{
+		body_8bitmime = 0;
+		done = synprot_error(L_smtp_syntax_error, 501, NULL,
+		  US"invalid data for BODY");
+		goto COMMAND_LOOP;
+		}
+	      DEBUG(D_receive) debug_printf("8BITMIME: %d\n", body_8bitmime);
+	      break;
+	    }
+	    arg_error = TRUE;
+	    break;
+
+	  /* Handle the two DSN options, but only if configured to do so (which
+	  will have caused "DSN" to be given in the EHLO response). The code itself
+	  is included only if configured in at build time. */
+
+	  case ENV_MAIL_OPT_RET:
+	    if (fl.dsn_advertised)
+	      {
+	      /* Check if RET has already been set */
+	      if (dsn_ret > 0)
+		{
+		done = synprot_error(L_smtp_syntax_error, 501, NULL,
+		  US"RET can be specified once only");
+		goto COMMAND_LOOP;
+		}
+	      dsn_ret = strcmpic(value, US"HDRS") == 0
+		? dsn_ret_hdrs
+		: strcmpic(value, US"FULL") == 0
+		? dsn_ret_full
+		: 0;
+	      DEBUG(D_receive) debug_printf("DSN_RET: %d\n", dsn_ret);
+	      /* Check for invalid invalid value, and exit with error */
+	      if (dsn_ret == 0)
+		{
+		done = synprot_error(L_smtp_syntax_error, 501, NULL,
+		  US"Value for RET is invalid");
+		goto COMMAND_LOOP;
+		}
+	      }
+	    break;
+	  case ENV_MAIL_OPT_ENVID:
+	    if (fl.dsn_advertised)
+	      {
+	      /* Check if the dsn envid has been already set */
+	      if (dsn_envid)
+		{
+		done = synprot_error(L_smtp_syntax_error, 501, NULL,
+		  US"ENVID can be specified once only");
+		goto COMMAND_LOOP;
+		}
+	      dsn_envid = string_copy(value);
+	      DEBUG(D_receive) debug_printf("DSN_ENVID: %s\n", dsn_envid);
+	      }
+	    break;
+
+	  /* Handle the AUTH extension. If the value given is not "<>" and either
+	  the ACL says "yes" or there is no ACL but the sending host is
+	  authenticated, we set it up as the authenticated sender. However, if the
+	  authenticator set a condition to be tested, we ignore AUTH on MAIL unless
+	  the condition is met. The value of AUTH is an xtext, which means that +,
+	  = and cntrl chars are coded in hex; however "<>" is unaffected by this
+	  coding. */
+	  case ENV_MAIL_OPT_AUTH:
+	    if (Ustrcmp(value, "<>") != 0)
+	      {
+	      int rc;
+	      uschar *ignore_msg;
+
+	      if (auth_xtextdecode(value, &authenticated_sender) < 0)
+		{
+		/* Put back terminator overrides for error message */
+		value[-1] = '=';
+		name[-1] = ' ';
+		done = synprot_error(L_smtp_syntax_error, 501, NULL,
+		  US"invalid data for AUTH");
+		goto COMMAND_LOOP;
+		}
+	      if (!acl_smtp_mailauth)
+		{
+		ignore_msg = US"client not authenticated";
+		rc = sender_host_authenticated ? OK : FAIL;
+		}
+	      else
+		{
+		ignore_msg = US"rejected by ACL";
+		rc = acl_check(ACL_WHERE_MAILAUTH, NULL, acl_smtp_mailauth,
+		  &user_msg, &log_msg);
+		}
+
+	      switch (rc)
+		{
+		case OK:
+		  if (authenticated_by == NULL ||
+		      authenticated_by->mail_auth_condition == NULL ||
+		      expand_check_condition(authenticated_by->mail_auth_condition,
+			  authenticated_by->name, US"authenticator"))
+		    break;     /* Accept the AUTH */
+
+		  ignore_msg = US"server_mail_auth_condition failed";
+		  if (authenticated_id != NULL)
+		    ignore_msg = string_sprintf("%s: authenticated ID=\"%s\"",
+		      ignore_msg, authenticated_id);
+
+		/* Fall through */
+
+		case FAIL:
+		  authenticated_sender = NULL;
+		  log_write(0, LOG_MAIN, "ignoring AUTH=%s from %s (%s)",
+		    value, host_and_ident(TRUE), ignore_msg);
+		  break;
+
+		/* Should only get DEFER or ERROR here. Put back terminator
+		overrides for error message */
+
+		default:
+		  value[-1] = '=';
+		  name[-1] = ' ';
+		  (void)smtp_handle_acl_fail(ACL_WHERE_MAILAUTH, rc, user_msg,
+		    log_msg);
+		  goto COMMAND_LOOP;
+		}
+	      }
+	      break;
+
+#ifndef DISABLE_PRDR
+	  case ENV_MAIL_OPT_PRDR:
+	    if (prdr_enable)
+	      prdr_requested = TRUE;
+	    break;
+#endif
+
+#ifdef SUPPORT_I18N
+	  case ENV_MAIL_OPT_UTF8:
+	    if (!fl.smtputf8_advertised)
+	      {
+	      done = synprot_error(L_smtp_syntax_error, 501, NULL,
+		US"SMTPUTF8 used when not advertised");
+	      goto COMMAND_LOOP;
+	      }
+
+	    DEBUG(D_receive) debug_printf("smtputf8 requested\n");
+	    message_smtputf8 = allow_utf8_domains = TRUE;
+	    if (Ustrncmp(received_protocol, US"utf8", 4) != 0)
+	      {
+	      int old_pool = store_pool;
+	      store_pool = POOL_PERM;
+	      received_protocol = string_sprintf("utf8%s", received_protocol);
+	      store_pool = old_pool;
+	      }
+	    break;
+#endif
+
+	  /* No valid option. Stick back the terminator characters and break
+	  the loop.  Do the name-terminator second as extract_option sets
+	  value==name when it found no equal-sign.
+	  An error for a malformed address will occur. */
+	  case ENV_MAIL_OPT_NULL:
+	    value[-1] = '=';
+	    name[-1] = ' ';
+	    arg_error = TRUE;
+	    break;
+
+	  default:  assert(0);
+	  }
+	/* Break out of for loop if switch() had bad argument or
+	   when start of the email address is reached */
+	if (arg_error) break;
+	}
+
+      /* If we have passed the threshold for rate limiting, apply the current
+      delay, and update it for next time, provided this is a limited host. */
+
+      if (smtp_mailcmd_count > smtp_rlm_threshold &&
+	  verify_check_host(&smtp_ratelimit_hosts) == OK)
+	{
+	DEBUG(D_receive) debug_printf("rate limit MAIL: delay %.3g sec\n",
+	  smtp_delay_mail/1000.0);
+	millisleep((int)smtp_delay_mail);
+	smtp_delay_mail *= smtp_rlm_factor;
+	if (smtp_delay_mail > (double)smtp_rlm_limit)
+	  smtp_delay_mail = (double)smtp_rlm_limit;
+	}
+
+      /* Now extract the address, first applying any SMTP-time rewriting. The
+      TRUE flag allows "<>" as a sender address. */
+
+      raw_sender = rewrite_existflags & rewrite_smtp
+	/* deconst ok as smtp_cmd_data was not const */
+	? US rewrite_one(smtp_cmd_data, rewrite_smtp, NULL, FALSE, US"",
+		      global_rewrite_rules)
+	: smtp_cmd_data;
+
+      raw_sender =
+	parse_extract_address(raw_sender, &errmess, &start, &end, &sender_domain,
+	  TRUE);
+
+      if (!raw_sender)
+	{
+	done = synprot_error(L_smtp_syntax_error, 501, smtp_cmd_data, errmess);
+	break;
+	}
+
+      sender_address = raw_sender;
+
+      /* If there is a configured size limit for mail, check that this message
+      doesn't exceed it. The check is postponed to this point so that the sender
+      can be logged. */
+
+      if (thismessage_size_limit > 0 && message_size > thismessage_size_limit)
+	{
+	smtp_printf("552 Message size exceeds maximum permitted\r\n", FALSE);
+	log_write(L_size_reject,
+	    LOG_MAIN|LOG_REJECT, "rejected MAIL FROM:<%s> %s: "
+	    "message too big: size%s=%d max=%d",
+	    sender_address,
+	    host_and_ident(TRUE),
+	    (message_size == INT_MAX)? ">" : "",
+	    message_size,
+	    thismessage_size_limit);
+	sender_address = NULL;
+	break;
+	}
+
+      /* Check there is enough space on the disk unless configured not to.
+      When smtp_check_spool_space is set, the check is for thismessage_size_limit
+      plus the current message - i.e. we accept the message only if it won't
+      reduce the space below the threshold. Add 5000 to the size to allow for
+      overheads such as the Received: line and storing of recipients, etc.
+      By putting the check here, even when SIZE is not given, it allow VRFY
+      and EXPN etc. to be used when space is short. */
+
+      if (!receive_check_fs(
+	   smtp_check_spool_space && message_size >= 0
+	      ? message_size + 5000 : 0))
+	{
+	smtp_printf("452 Space shortage, please try later\r\n", FALSE);
+	sender_address = NULL;
+	break;
+	}
+
+      /* If sender_address is unqualified, reject it, unless this is a locally
+      generated message, or the sending host or net is permitted to send
+      unqualified addresses - typically local machines behaving as MUAs -
+      in which case just qualify the address. The flag is set above at the start
+      of the SMTP connection. */
+
+      if (!sender_domain && *sender_address)
+	if (f.allow_unqualified_sender)
+	  {
+	  sender_domain = Ustrlen(sender_address) + 1;
+	  /* deconst ok as sender_address was not const */
+	  sender_address = US rewrite_address_qualify(sender_address, FALSE);
+	  DEBUG(D_receive) debug_printf("unqualified address %s accepted\n",
+	    raw_sender);
+	  }
+	else
+	  {
+	  smtp_printf("501 %s: sender address must contain a domain\r\n", FALSE,
+	    smtp_cmd_data);
+	  log_write(L_smtp_syntax_error,
+	    LOG_MAIN|LOG_REJECT,
+	    "unqualified sender rejected: <%s> %s%s",
+	    raw_sender,
+	    host_and_ident(TRUE),
+	    host_lookup_msg);
+	  sender_address = NULL;
+	  break;
+	  }
+
+      /* Apply an ACL check if one is defined, before responding. Afterwards,
+      when pipelining is not advertised, do another sync check in case the ACL
+      delayed and the client started sending in the meantime. */
+
+      if (acl_smtp_mail)
+	{
+	rc = acl_check(ACL_WHERE_MAIL, NULL, acl_smtp_mail, &user_msg, &log_msg);
+	if (rc == OK && !f.smtp_in_pipelining_advertised && !check_sync())
+	  goto SYNC_FAILURE;
+	}
+      else
+	rc = OK;
+
+      if (rc == OK || rc == DISCARD)
+	{
+	BOOL more = pipeline_response();
+
+	if (!user_msg)
+	  smtp_printf("%s%s%s", more, US"250 OK",
+		    #ifndef DISABLE_PRDR
+		      prdr_requested ? US", PRDR Requested" : US"",
+		    #else
+		      US"",
+		    #endif
+		      US"\r\n");
+	else
+	  {
+	#ifndef DISABLE_PRDR
+	  if (prdr_requested)
+	     user_msg = string_sprintf("%s%s", user_msg, US", PRDR Requested");
+	#endif
+	  smtp_user_msg(US"250", user_msg);
+	  }
+	smtp_delay_rcpt = smtp_rlr_base;
+	f.recipients_discarded = (rc == DISCARD);
+	was_rej_mail = FALSE;
+	}
+      else
+	{
+	done = smtp_handle_acl_fail(ACL_WHERE_MAIL, rc, user_msg, log_msg);
+	sender_address = NULL;
+	}
+      break;
+
+
+    /* The RCPT command requires an address as an operand. There may be any
+    number of RCPT commands, specifying multiple recipients. We build them all
+    into a data structure. The start/end values given by parse_extract_address
+    are not used, as we keep only the extracted address. */
+
+    case RCPT_CMD:
+      HAD(SCH_RCPT);
+      /* We got really to many recipients. A check against configured
+      limits is done later */
+      if (rcpt_count < 0 || rcpt_count >= INT_MAX/2)
+        log_write(0, LOG_MAIN|LOG_PANIC_DIE, "Too many recipients: %d", rcpt_count);
+      rcpt_count++;
+      was_rcpt = fl.rcpt_in_progress = TRUE;
+
+      /* There must be a sender address; if the sender was rejected and
+      pipelining was advertised, we assume the client was pipelining, and do not
+      count this as a protocol error. Reset was_rej_mail so that further RCPTs
+      get the same treatment. */
+
+      if (!sender_address)
+	{
+	if (f.smtp_in_pipelining_advertised && last_was_rej_mail)
+	  {
+	  smtp_printf("503 sender not yet given\r\n", FALSE);
+	  was_rej_mail = TRUE;
+	  }
+	else
+	  {
+	  done = synprot_error(L_smtp_protocol_error, 503, NULL,
+	    US"sender not yet given");
+	  was_rcpt = FALSE;             /* Not a valid RCPT */
+	  }
+	rcpt_fail_count++;
+	break;
+	}
+
+      /* Check for an operand */
+
+      if (!smtp_cmd_data[0])
+	{
+	done = synprot_error(L_smtp_syntax_error, 501, NULL,
+	  US"RCPT must have an address operand");
+	rcpt_fail_count++;
+	break;
+	}
+
+      /* Set the DSN flags orcpt and dsn_flags from the session*/
+      orcpt = NULL;
+      dsn_flags = 0;
+
+      if (fl.esmtp) for(;;)
+	{
+	uschar *name, *value;
+
+	if (!extract_option(&name, &value))
+	  break;
+
+	if (fl.dsn_advertised && strcmpic(name, US"ORCPT") == 0)
+	  {
+	  /* Check whether orcpt has been already set */
+	  if (orcpt)
+	    {
+	    done = synprot_error(L_smtp_syntax_error, 501, NULL,
+	      US"ORCPT can be specified once only");
+	    goto COMMAND_LOOP;
+	    }
+	  orcpt = string_copy(value);
+	  DEBUG(D_receive) debug_printf("DSN orcpt: %s\n", orcpt);
+	  }
+
+	else if (fl.dsn_advertised && strcmpic(name, US"NOTIFY") == 0)
+	  {
+	  /* Check if the notify flags have been already set */
+	  if (dsn_flags > 0)
+	    {
+	    done = synprot_error(L_smtp_syntax_error, 501, NULL,
+		US"NOTIFY can be specified once only");
+	    goto COMMAND_LOOP;
+	    }
+	  if (strcmpic(value, US"NEVER") == 0)
+	    dsn_flags |= rf_notify_never;
+	  else
+	    {
+	    uschar *p = value;
+	    while (*p != 0)
+	      {
+	      uschar *pp = p;
+	      while (*pp != 0 && *pp != ',') pp++;
+	      if (*pp == ',') *pp++ = 0;
+	      if (strcmpic(p, US"SUCCESS") == 0)
+		{
+		DEBUG(D_receive) debug_printf("DSN: Setting notify success\n");
+		dsn_flags |= rf_notify_success;
+		}
+	      else if (strcmpic(p, US"FAILURE") == 0)
+		{
+		DEBUG(D_receive) debug_printf("DSN: Setting notify failure\n");
+		dsn_flags |= rf_notify_failure;
+		}
+	      else if (strcmpic(p, US"DELAY") == 0)
+		{
+		DEBUG(D_receive) debug_printf("DSN: Setting notify delay\n");
+		dsn_flags |= rf_notify_delay;
+		}
+	      else
+		{
+		/* Catch any strange values */
+		done = synprot_error(L_smtp_syntax_error, 501, NULL,
+		  US"Invalid value for NOTIFY parameter");
+		goto COMMAND_LOOP;
+		}
+	      p = pp;
+	      }
+	      DEBUG(D_receive) debug_printf("DSN Flags: %x\n", dsn_flags);
+	    }
+	  }
+
+	/* Unknown option. Stick back the terminator characters and break
+	the loop. An error for a malformed address will occur. */
+
+	else
+	  {
+	  DEBUG(D_receive) debug_printf("Invalid RCPT option: %s : %s\n", name, value);
+	  name[-1] = ' ';
+	  value[-1] = '=';
+	  break;
+	  }
+	}
+
+      /* Apply SMTP rewriting then extract the working address. Don't allow "<>"
+      as a recipient address */
+
+      recipient = rewrite_existflags & rewrite_smtp
+	/* deconst ok as smtp_cmd_data was not const */
+	? US rewrite_one(smtp_cmd_data, rewrite_smtp, NULL, FALSE, US"",
+	    global_rewrite_rules)
+	: smtp_cmd_data;
+
+      if (!(recipient = parse_extract_address(recipient, &errmess, &start, &end,
+	&recipient_domain, FALSE)))
+	{
+	done = synprot_error(L_smtp_syntax_error, 501, smtp_cmd_data, errmess);
+	rcpt_fail_count++;
+	break;
+	}
+
+      /* If the recipient address is unqualified, reject it, unless this is a
+      locally generated message. However, unqualified addresses are permitted
+      from a configured list of hosts and nets - typically when behaving as
+      MUAs rather than MTAs. Sad that SMTP is used for both types of traffic,
+      really. The flag is set at the start of the SMTP connection.
+
+      RFC 1123 talks about supporting "the reserved mailbox postmaster"; I always
+      assumed this meant "reserved local part", but the revision of RFC 821 and
+      friends now makes it absolutely clear that it means *mailbox*. Consequently
+      we must always qualify this address, regardless. */
+
+      if (!recipient_domain)
+	if (!(recipient_domain = qualify_recipient(&recipient, smtp_cmd_data,
+				    US"recipient")))
+	  {
+	  rcpt_fail_count++;
+	  break;
+	  }
+
+      /* Check maximum allowed */
+
+      if (rcpt_count+1 < 0 || rcpt_count > recipients_max && recipients_max > 0)
+	{
+	if (recipients_max_reject)
+	  {
+	  rcpt_fail_count++;
+	  smtp_printf("552 too many recipients\r\n", FALSE);
+	  if (!toomany)
+	    log_write(0, LOG_MAIN|LOG_REJECT, "too many recipients: message "
+	      "rejected: sender=<%s> %s", sender_address, host_and_ident(TRUE));
+	  }
+	else
+	  {
+	  rcpt_defer_count++;
+	  smtp_printf("452 too many recipients\r\n", FALSE);
+	  if (!toomany)
+	    log_write(0, LOG_MAIN|LOG_REJECT, "too many recipients: excess "
+	      "temporarily rejected: sender=<%s> %s", sender_address,
+	      host_and_ident(TRUE));
+	  }
+
+	toomany = TRUE;
+	break;
+	}
+
+      /* If we have passed the threshold for rate limiting, apply the current
+      delay, and update it for next time, provided this is a limited host. */
+
+      if (rcpt_count > smtp_rlr_threshold &&
+	  verify_check_host(&smtp_ratelimit_hosts) == OK)
+	{
+	DEBUG(D_receive) debug_printf("rate limit RCPT: delay %.3g sec\n",
+	  smtp_delay_rcpt/1000.0);
+	millisleep((int)smtp_delay_rcpt);
+	smtp_delay_rcpt *= smtp_rlr_factor;
+	if (smtp_delay_rcpt > (double)smtp_rlr_limit)
+	  smtp_delay_rcpt = (double)smtp_rlr_limit;
+	}
+
+      /* If the MAIL ACL discarded all the recipients, we bypass ACL checking
+      for them. Otherwise, check the access control list for this recipient. As
+      there may be a delay in this, re-check for a synchronization error
+      afterwards, unless pipelining was advertised. */
+
+      if (f.recipients_discarded)
+	rc = DISCARD;
+      else
+	if (  (rc = acl_check(ACL_WHERE_RCPT, recipient, acl_smtp_rcpt, &user_msg,
+		      &log_msg)) == OK
+	   && !f.smtp_in_pipelining_advertised && !check_sync())
+	  goto SYNC_FAILURE;
+
+      /* The ACL was happy */
+
+      if (rc == OK)
+	{
+	BOOL more = pipeline_response();
+
+	if (user_msg)
+	  smtp_user_msg(US"250", user_msg);
+	else
+	  smtp_printf("250 Accepted\r\n", more);
+	receive_add_recipient(recipient, -1);
+
+	/* Set the dsn flags in the recipients_list */
+	recipients_list[recipients_count-1].orcpt = orcpt;
+	recipients_list[recipients_count-1].dsn_flags = dsn_flags;
+
+	/* DEBUG(D_receive) debug_printf("DSN: orcpt: %s  flags: %d\n",
+	  recipients_list[recipients_count-1].orcpt,
+	  recipients_list[recipients_count-1].dsn_flags); */
+	}
+
+      /* The recipient was discarded */
+
+      else if (rc == DISCARD)
+	{
+	if (user_msg)
+	  smtp_user_msg(US"250", user_msg);
+	else
+	  smtp_printf("250 Accepted\r\n", FALSE);
+	rcpt_fail_count++;
+	discarded = TRUE;
+	log_write(0, LOG_MAIN|LOG_REJECT, "%s F=<%s> RCPT %s: "
+	  "discarded by %s ACL%s%s", host_and_ident(TRUE),
+	  sender_address_unrewritten ? sender_address_unrewritten : sender_address,
+	  smtp_cmd_argument, f.recipients_discarded ? "MAIL" : "RCPT",
+	  log_msg ? US": " : US"", log_msg ? log_msg : US"");
+	}
+
+      /* Either the ACL failed the address, or it was deferred. */
+
+      else
+	{
+	if (rc == FAIL) rcpt_fail_count++; else rcpt_defer_count++;
+	done = smtp_handle_acl_fail(ACL_WHERE_RCPT, rc, user_msg, log_msg);
+	}
+      break;
+
+
+    /* The DATA command is legal only if it follows successful MAIL FROM
+    and RCPT TO commands. However, if pipelining is advertised, a bad DATA is
+    not counted as a protocol error if it follows RCPT (which must have been
+    rejected if there are no recipients.) This function is complete when a
+    valid DATA command is encountered.
+
+    Note concerning the code used: RFC 2821 says this:
+
+     -  If there was no MAIL, or no RCPT, command, or all such commands
+        were rejected, the server MAY return a "command out of sequence"
+        (503) or "no valid recipients" (554) reply in response to the
+        DATA command.
+
+    The example in the pipelining RFC 2920 uses 554, but I use 503 here
+    because it is the same whether pipelining is in use or not.
+
+    If all the RCPT commands that precede DATA provoked the same error message
+    (often indicating some kind of system error), it is helpful to include it
+    with the DATA rejection (an idea suggested by Tony Finch). */
+
+    case BDAT_CMD:
+      {
+      int n;
+
+      HAD(SCH_BDAT);
+      if (chunking_state != CHUNKING_OFFERED)
+	{
+	done = synprot_error(L_smtp_protocol_error, 503, NULL,
+	  US"BDAT command used when CHUNKING not advertised");
+	break;
+	}
+
+      /* grab size, endmarker */
+
+      if (sscanf(CS smtp_cmd_data, "%u %n", &chunking_datasize, &n) < 1)
+	{
+	done = synprot_error(L_smtp_protocol_error, 501, NULL,
+	  US"missing size for BDAT command");
+	break;
+	}
+      chunking_state = strcmpic(smtp_cmd_data+n, US"LAST") == 0
+	? CHUNKING_LAST : CHUNKING_ACTIVE;
+      chunking_data_left = chunking_datasize;
+      DEBUG(D_receive) debug_printf("chunking state %d, %d bytes\n",
+				    (int)chunking_state, chunking_data_left);
+
+      f.bdat_readers_wanted = TRUE; /* FIXME: redundant vs chunking_state? */
+      f.dot_ends = FALSE;
+
+      goto DATA_BDAT;
+      }
+
+    case DATA_CMD:
+      HAD(SCH_DATA);
+      f.dot_ends = TRUE;
+      f.bdat_readers_wanted = FALSE;
+
+    DATA_BDAT:		/* Common code for DATA and BDAT */
+#ifndef DISABLE_PIPE_CONNECT
+      fl.pipe_connect_acceptable = FALSE;
+#endif
+      if (!discarded && recipients_count <= 0)
+	{
+	if (fl.rcpt_smtp_response_same && rcpt_smtp_response)
+	  {
+	  uschar *code = US"503";
+	  int len = Ustrlen(rcpt_smtp_response);
+	  smtp_respond(code, 3, FALSE, US"All RCPT commands were rejected with "
+	    "this error:");
+	  /* Responses from smtp_printf() will have \r\n on the end */
+	  if (len > 2 && rcpt_smtp_response[len-2] == '\r')
+	    rcpt_smtp_response[len-2] = 0;
+	  smtp_respond(code, 3, FALSE, rcpt_smtp_response);
+	  }
+	if (f.smtp_in_pipelining_advertised && last_was_rcpt)
+	  smtp_printf("503 Valid RCPT command must precede %s\r\n", FALSE,
+	    smtp_names[smtp_connection_had[SMTP_HBUFF_PREV(smtp_ch_index)]]);
+	else
+	  done = synprot_error(L_smtp_protocol_error, 503, NULL,
+	    smtp_connection_had[SMTP_HBUFF_PREV(smtp_ch_index)] == SCH_DATA
+	    ? US"valid RCPT command must precede DATA"
+	    : US"valid RCPT command must precede BDAT");
+
+	if (chunking_state > CHUNKING_OFFERED)
+	  {
+	  bdat_push_receive_functions();
+	  bdat_flush_data();
+	  }
+	break;
+	}
+
+      if (toomany && recipients_max_reject)
+	{
+	sender_address = NULL;  /* This will allow a new MAIL without RSET */
+	sender_address_unrewritten = NULL;
+	smtp_printf("554 Too many recipients\r\n", FALSE);
+
+	if (chunking_state > CHUNKING_OFFERED)
+	  {
+	  bdat_push_receive_functions();
+	  bdat_flush_data();
+	  }
+	break;
+	}
+
+      if (chunking_state > CHUNKING_OFFERED)
+	rc = OK;			/* No predata ACL or go-ahead output for BDAT */
+      else
+	{
+	/* If there is an ACL, re-check the synchronization afterwards, since the
+	ACL may have delayed.  To handle cutthrough delivery enforce a dummy call
+	to get the DATA command sent. */
+
+	if (!acl_smtp_predata && cutthrough.cctx.sock < 0)
+	  rc = OK;
+	else
+	  {
+	  uschar * acl = acl_smtp_predata ? acl_smtp_predata : US"accept";
+	  f.enable_dollar_recipients = TRUE;
+	  rc = acl_check(ACL_WHERE_PREDATA, NULL, acl, &user_msg,
+	    &log_msg);
+	  f.enable_dollar_recipients = FALSE;
+	  if (rc == OK && !check_sync())
+	    goto SYNC_FAILURE;
+
+	  if (rc != OK)
+	    {	/* Either the ACL failed the address, or it was deferred. */
+	    done = smtp_handle_acl_fail(ACL_WHERE_PREDATA, rc, user_msg, log_msg);
+	    break;
+	    }
+	  }
+
+	if (user_msg)
+	  smtp_user_msg(US"354", user_msg);
+	else
+	  smtp_printf(
+	    "354 Enter message, ending with \".\" on a line by itself\r\n", FALSE);
+	}
+
+      if (f.bdat_readers_wanted)
+	bdat_push_receive_functions();
+
+#ifdef TCP_QUICKACK
+      if (smtp_in)	/* all ACKs needed to ramp window up for bulk data */
+	(void) setsockopt(fileno(smtp_in), IPPROTO_TCP, TCP_QUICKACK,
+		US &on, sizeof(on));
+#endif
+      done = 3;
+      message_ended = END_NOTENDED;   /* Indicate in middle of data */
+
+      break;
+
+
+    case VRFY_CMD:
+      {
+      uschar * address;
+
+      HAD(SCH_VRFY);
+
+      if (!(address = parse_extract_address(smtp_cmd_data, &errmess,
+            &start, &end, &recipient_domain, FALSE)))
+	{
+	smtp_printf("501 %s\r\n", FALSE, errmess);
+	break;
+	}
+
+      if (!recipient_domain)
+	if (!(recipient_domain = qualify_recipient(&address, smtp_cmd_data,
+				    US"verify")))
+	  break;
+
+      if ((rc = acl_check(ACL_WHERE_VRFY, address, acl_smtp_vrfy,
+		    &user_msg, &log_msg)) != OK)
+	done = smtp_handle_acl_fail(ACL_WHERE_VRFY, rc, user_msg, log_msg);
+      else
+	{
+	uschar * s = NULL;
+	address_item * addr = deliver_make_addr(address, FALSE);
+
+	switch(verify_address(addr, NULL, vopt_is_recipient | vopt_qualify, -1,
+	       -1, -1, NULL, NULL, NULL))
+	  {
+	  case OK:
+	    s = string_sprintf("250 <%s> is deliverable", address);
+	    break;
+
+	  case DEFER:
+	    s = (addr->user_message != NULL)?
+	      string_sprintf("451 <%s> %s", address, addr->user_message) :
+	      string_sprintf("451 Cannot resolve <%s> at this time", address);
+	    break;
+
+	  case FAIL:
+	    s = (addr->user_message != NULL)?
+	      string_sprintf("550 <%s> %s", address, addr->user_message) :
+	      string_sprintf("550 <%s> is not deliverable", address);
+	    log_write(0, LOG_MAIN, "VRFY failed for %s %s",
+	      smtp_cmd_argument, host_and_ident(TRUE));
+	    break;
+	  }
+
+	smtp_printf("%s\r\n", FALSE, s);
+	}
+      break;
+      }
+
+
+    case EXPN_CMD:
+      HAD(SCH_EXPN);
+      rc = acl_check(ACL_WHERE_EXPN, NULL, acl_smtp_expn, &user_msg, &log_msg);
+      if (rc != OK)
+	done = smtp_handle_acl_fail(ACL_WHERE_EXPN, rc, user_msg, log_msg);
+      else
+	{
+	BOOL save_log_testing_mode = f.log_testing_mode;
+	f.address_test_mode = f.log_testing_mode = TRUE;
+	(void) verify_address(deliver_make_addr(smtp_cmd_data, FALSE),
+	  smtp_out, vopt_is_recipient | vopt_qualify | vopt_expn, -1, -1, -1,
+	  NULL, NULL, NULL);
+	f.address_test_mode = FALSE;
+	f.log_testing_mode = save_log_testing_mode;    /* true for -bh */
+	}
+      break;
+
+
+    #ifndef DISABLE_TLS
+
+    case STARTTLS_CMD:
+      HAD(SCH_STARTTLS);
+      if (!fl.tls_advertised)
+	{
+	done = synprot_error(L_smtp_protocol_error, 503, NULL,
+	  US"STARTTLS command used when not advertised");
+	break;
+	}
+
+      /* Apply an ACL check if one is defined */
+
+      if (  acl_smtp_starttls
+	 && (rc = acl_check(ACL_WHERE_STARTTLS, NULL, acl_smtp_starttls,
+		    &user_msg, &log_msg)) != OK
+	 )
+	{
+	done = smtp_handle_acl_fail(ACL_WHERE_STARTTLS, rc, user_msg, log_msg);
+	break;
+	}
+
+      /* RFC 2487 is not clear on when this command may be sent, though it
+      does state that all information previously obtained from the client
+      must be discarded if a TLS session is started. It seems reasonable to
+      do an implied RSET when STARTTLS is received. */
+
+      incomplete_transaction_log(US"STARTTLS");
+      cancel_cutthrough_connection(TRUE, US"STARTTLS received");
+      reset_point = smtp_reset(reset_point);
+      toomany = FALSE;
+      cmd_list[CMD_LIST_STARTTLS].is_mail_cmd = FALSE;
+
+      /* There's an attack where more data is read in past the STARTTLS command
+      before TLS is negotiated, then assumed to be part of the secure session
+      when used afterwards; we use segregated input buffers, so are not
+      vulnerable, but we want to note when it happens and, for sheer paranoia,
+      ensure that the buffer is "wiped".
+      Pipelining sync checks will normally have protected us too, unless disabled
+      by configuration. */
+
+      if (receive_hasc())
+	{
+	DEBUG(D_any)
+	  debug_printf("Non-empty input buffer after STARTTLS; naive attack?\n");
+	if (tls_in.active.sock < 0)
+	  smtp_inend = smtp_inptr = smtp_inbuffer;
+	/* and if TLS is already active, tls_server_start() should fail */
+	}
+
+      /* There is nothing we value in the input buffer and if TLS is successfully
+      negotiated, we won't use this buffer again; if TLS fails, we'll just read
+      fresh content into it.  The buffer contains arbitrary content from an
+      untrusted remote source; eg: NOOP <shellcode>\r\nSTARTTLS\r\n
+      It seems safest to just wipe away the content rather than leave it as a
+      target to jump to. */
+
+      memset(smtp_inbuffer, 0, IN_BUFFER_SIZE);
+
+      /* Attempt to start up a TLS session, and if successful, discard all
+      knowledge that was obtained previously. At least, that's what the RFC says,
+      and that's what happens by default. However, in order to work round YAEB,
+      there is an option to remember the esmtp state. Sigh.
+
+      We must allow for an extra EHLO command and an extra AUTH command after
+      STARTTLS that don't add to the nonmail command count. */
+
+      s = NULL;
+      if ((rc = tls_server_start(&s)) == OK)
+	{
+	if (!tls_remember_esmtp)
+	  fl.helo_seen = fl.esmtp = fl.auth_advertised = f.smtp_in_pipelining_advertised = FALSE;
+	cmd_list[CMD_LIST_EHLO].is_mail_cmd = TRUE;
+	cmd_list[CMD_LIST_AUTH].is_mail_cmd = TRUE;
+	cmd_list[CMD_LIST_TLS_AUTH].is_mail_cmd = TRUE;
+	if (sender_helo_name)
+	  {
+	  sender_helo_name = NULL;
+	  host_build_sender_fullhost();  /* Rebuild */
+	  set_process_info("handling incoming TLS connection from %s",
+	    host_and_ident(FALSE));
+	  }
+	received_protocol =
+	  (sender_host_address ? protocols : protocols_local)
+	    [ (fl.esmtp
+	      ? pextend + (sender_host_authenticated ? pauthed : 0)
+	      : pnormal)
+	    + (tls_in.active.sock >= 0 ? pcrpted : 0)
+	    ];
+
+	sender_host_auth_pubname = sender_host_authenticated = NULL;
+	authenticated_id = NULL;
+	sync_cmd_limit = NON_SYNC_CMD_NON_PIPELINING;
+	DEBUG(D_tls) debug_printf("TLS active\n");
+	break;     /* Successful STARTTLS */
+	}
+      else
+	(void) smtp_log_tls_fail(s);
+
+      /* Some local configuration problem was discovered before actually trying
+      to do a TLS handshake; give a temporary error. */
+
+      if (rc == DEFER)
+	{
+	smtp_printf("454 TLS currently unavailable\r\n", FALSE);
+	break;
+	}
+
+      /* Hard failure. Reject everything except QUIT or closed connection. One
+      cause for failure is a nested STARTTLS, in which case tls_in.active remains
+      set, but we must still reject all incoming commands.  Another is a handshake
+      failure - and there may some encrypted data still in the pipe to us, which we
+      see as garbage commands. */
+
+      DEBUG(D_tls) debug_printf("TLS failed to start\n");
+      while (done <= 0) switch(smtp_read_command(FALSE, GETC_BUFFER_UNLIMITED))
+	{
+	case EOF_CMD:
+	  log_write(L_smtp_connection, LOG_MAIN, "%s closed by EOF",
+	    smtp_get_connection_info());
+	  smtp_notquit_exit(US"tls-failed", NULL, NULL);
+	  done = 2;
+	  break;
+
+	/* It is perhaps arguable as to which exit ACL should be called here,
+	but as it is probably a situation that almost never arises, it
+	probably doesn't matter. We choose to call the real QUIT ACL, which in
+	some sense is perhaps "right". */
+
+	case QUIT_CMD:
+	  f.smtp_in_quit = TRUE;
+	  user_msg = NULL;
+	  if (  acl_smtp_quit
+	     && ((rc = acl_check(ACL_WHERE_QUIT, NULL, acl_smtp_quit, &user_msg,
+				&log_msg)) == ERROR))
+	      log_write(0, LOG_MAIN|LOG_PANIC, "ACL for QUIT returned ERROR: %s",
+		log_msg);
+	  if (user_msg)
+	    smtp_respond(US"221", 3, TRUE, user_msg);
+	  else
+	    smtp_printf("221 %s closing connection\r\n", FALSE, smtp_active_hostname);
+	  log_write(L_smtp_connection, LOG_MAIN, "%s closed by QUIT",
+	    smtp_get_connection_info());
+	  done = 2;
+	  break;
+
+	default:
+	  smtp_printf("554 Security failure\r\n", FALSE);
+	  break;
+	}
+      tls_close(NULL, TLS_SHUTDOWN_NOWAIT);
+      break;
+    #endif
+
+
+    /* The ACL for QUIT is provided for gathering statistical information or
+    similar; it does not affect the response code, but it can supply a custom
+    message. */
+
+    case QUIT_CMD:
+      smtp_quit_handler(&user_msg, &log_msg);
+      done = 2;
+      break;
+
+
+    case RSET_CMD:
+      smtp_rset_handler();
+      cancel_cutthrough_connection(TRUE, US"RSET received");
+      reset_point = smtp_reset(reset_point);
+      toomany = FALSE;
+      break;
+
+
+    case NOOP_CMD:
+      HAD(SCH_NOOP);
+      smtp_printf("250 OK\r\n", FALSE);
+      break;
+
+
+    /* Show ETRN/EXPN/VRFY if there's an ACL for checking hosts; if actually
+    used, a check will be done for permitted hosts. Show STARTTLS only if not
+    already in a TLS session and if it would be advertised in the EHLO
+    response. */
+
+    case HELP_CMD:
+      HAD(SCH_HELP);
+      smtp_printf("214-Commands supported:\r\n", TRUE);
+	{
+	uschar buffer[256];
+	buffer[0] = 0;
+	Ustrcat(buffer, US" AUTH");
+	#ifndef DISABLE_TLS
+	if (tls_in.active.sock < 0 &&
+	    verify_check_host(&tls_advertise_hosts) != FAIL)
+	  Ustrcat(buffer, US" STARTTLS");
+	#endif
+	Ustrcat(buffer, US" HELO EHLO MAIL RCPT DATA BDAT");
+	Ustrcat(buffer, US" NOOP QUIT RSET HELP");
+	if (acl_smtp_etrn) Ustrcat(buffer, US" ETRN");
+	if (acl_smtp_expn) Ustrcat(buffer, US" EXPN");
+	if (acl_smtp_vrfy) Ustrcat(buffer, US" VRFY");
+	smtp_printf("214%s\r\n", FALSE, buffer);
+	}
+      break;
+
+
+    case EOF_CMD:
+      incomplete_transaction_log(US"connection lost");
+      smtp_notquit_exit(US"connection-lost", US"421",
+	US"%s lost input connection", smtp_active_hostname);
+
+      /* Don't log by default unless in the middle of a message, as some mailers
+      just drop the call rather than sending QUIT, and it clutters up the logs.
+      */
+
+      if (sender_address || recipients_count > 0)
+	log_write(L_lost_incoming_connection, LOG_MAIN,
+	  "unexpected %s while reading SMTP command from %s%s%s D=%s",
+	  f.sender_host_unknown ? "EOF" : "disconnection",
+	  f.tcp_in_fastopen_logged
+	  ? US""
+	  : f.tcp_in_fastopen
+	  ? f.tcp_in_fastopen_data ? US"TFO* " : US"TFO "
+	  : US"",
+	  host_and_ident(FALSE), smtp_read_error,
+	  string_timesince(&smtp_connection_start)
+	  );
+
+      else
+	log_write(L_smtp_connection, LOG_MAIN, "%s %slost%s D=%s",
+	  smtp_get_connection_info(),
+	  f.tcp_in_fastopen && !f.tcp_in_fastopen_logged ? US"TFO " : US"",
+	  smtp_read_error,
+	  string_timesince(&smtp_connection_start)
+	  );
+
+      done = 1;
+      break;
+
+
+    case ETRN_CMD:
+      HAD(SCH_ETRN);
+      if (sender_address)
+	{
+	done = synprot_error(L_smtp_protocol_error, 503, NULL,
+	  US"ETRN is not permitted inside a transaction");
+	break;
+	}
+
+      log_write(L_etrn, LOG_MAIN, "ETRN %s received from %s", smtp_cmd_argument,
+	host_and_ident(FALSE));
+
+      if ((rc = acl_check(ACL_WHERE_ETRN, NULL, acl_smtp_etrn,
+		  &user_msg, &log_msg)) != OK)
+	{
+	done = smtp_handle_acl_fail(ACL_WHERE_ETRN, rc, user_msg, log_msg);
+	break;
+	}
+
+      /* Compute the serialization key for this command. */
+
+      etrn_serialize_key = string_sprintf("etrn-%s\n", smtp_cmd_data);
+
+      /* If a command has been specified for running as a result of ETRN, we
+      permit any argument to ETRN. If not, only the # standard form is permitted,
+      since that is strictly the only kind of ETRN that can be implemented
+      according to the RFC. */
+
+      if (smtp_etrn_command)
+	{
+	uschar *error;
+	BOOL rc;
+	etrn_command = smtp_etrn_command;
+	deliver_domain = smtp_cmd_data;
+	rc = transport_set_up_command(&argv, smtp_etrn_command, TRUE, 0, NULL,
+	  FALSE, US"ETRN processing", &error);
+	deliver_domain = NULL;
+	if (!rc)
+	  {
+	  log_write(0, LOG_MAIN|LOG_PANIC, "failed to set up ETRN command: %s",
+	    error);
+	  smtp_printf("458 Internal failure\r\n", FALSE);
+	  break;
+	  }
+	}
+
+      /* Else set up to call Exim with the -R option. */
+
+      else
+	{
+	if (*smtp_cmd_data++ != '#')
+	  {
+	  done = synprot_error(L_smtp_syntax_error, 501, NULL,
+	    US"argument must begin with #");
+	  break;
+	  }
+	etrn_command = US"exim -R";
+	argv = CUSS child_exec_exim(CEE_RETURN_ARGV, TRUE, NULL, TRUE,
+	  *queue_name ? 4 : 2,
+	  US"-R", smtp_cmd_data,
+	  US"-MCG", queue_name);
+	}
+
+      /* If we are host-testing, don't actually do anything. */
+
+      if (host_checking)
+	{
+	HDEBUG(D_any)
+	  {
+	  debug_printf("ETRN command is: %s\n", etrn_command);
+	  debug_printf("ETRN command execution skipped\n");
+	  }
+	if (user_msg == NULL) smtp_printf("250 OK\r\n", FALSE);
+	  else smtp_user_msg(US"250", user_msg);
+	break;
+	}
+
+
+      /* If ETRN queue runs are to be serialized, check the database to
+      ensure one isn't already running. */
+
+      if (smtp_etrn_serialize && !enq_start(etrn_serialize_key, 1))
+	{
+	smtp_printf("458 Already processing %s\r\n", FALSE, smtp_cmd_data);
+	break;
+	}
+
+      /* Fork a child process and run the command. We don't want to have to
+      wait for the process at any point, so set SIGCHLD to SIG_IGN before
+      forking. It should be set that way anyway for external incoming SMTP,
+      but we save and restore to be tidy. If serialization is required, we
+      actually run the command in yet another process, so we can wait for it
+      to complete and then remove the serialization lock. */
+
+      oldsignal = signal(SIGCHLD, SIG_IGN);
+
+      if ((pid = exim_fork(US"etrn-command")) == 0)
+	{
+	smtp_input = FALSE;       /* This process is not associated with the */
+	(void)fclose(smtp_in);    /* SMTP call any more. */
+	(void)fclose(smtp_out);
+
+	signal(SIGCHLD, SIG_DFL);      /* Want to catch child */
+
+	/* If not serializing, do the exec right away. Otherwise, fork down
+	into another process. */
+
+	if (  !smtp_etrn_serialize
+	   || (pid = exim_fork(US"etrn-serialised-command")) == 0)
+	  {
+	  DEBUG(D_exec) debug_print_argv(argv);
+	  exim_nullstd();                   /* Ensure std{in,out,err} exist */
+	  /* argv[0] should be untainted, from child_exec_exim() */
+	  execv(CS argv[0], (char *const *)argv);
+	  log_write(0, LOG_MAIN|LOG_PANIC_DIE, "exec of \"%s\" (ETRN) failed: %s",
+	    etrn_command, strerror(errno));
+	  _exit(EXIT_FAILURE);         /* paranoia */
+	  }
+
+	/* Obey this if smtp_serialize and the 2nd fork yielded non-zero. That
+	is, we are in the first subprocess, after forking again. All we can do
+	for a failing fork is to log it. Otherwise, wait for the 2nd process to
+	complete, before removing the serialization. */
+
+	if (pid < 0)
+	  log_write(0, LOG_MAIN|LOG_PANIC, "2nd fork for serialized ETRN "
+	    "failed: %s", strerror(errno));
+	else
+	  {
+	  int status;
+	  DEBUG(D_any) debug_printf("waiting for serialized ETRN process %d\n",
+	    (int)pid);
+	  (void)wait(&status);
+	  DEBUG(D_any) debug_printf("serialized ETRN process %d ended\n",
+	    (int)pid);
+	  }
+
+	enq_end(etrn_serialize_key);
+	exim_underbar_exit(EXIT_SUCCESS);
+	}
+
+      /* Back in the top level SMTP process. Check that we started a subprocess
+      and restore the signal state. */
+
+      if (pid < 0)
+	{
+	log_write(0, LOG_MAIN|LOG_PANIC, "fork of process for ETRN failed: %s",
+	  strerror(errno));
+	smtp_printf("458 Unable to fork process\r\n", FALSE);
+	if (smtp_etrn_serialize) enq_end(etrn_serialize_key);
+	}
+      else
+	if (!user_msg)
+	  smtp_printf("250 OK\r\n", FALSE);
+	else
+	  smtp_user_msg(US"250", user_msg);
+
+      signal(SIGCHLD, oldsignal);
+      break;
+
+
+    case BADARG_CMD:
+      done = synprot_error(L_smtp_syntax_error, 501, NULL,
+	US"unexpected argument data");
+      break;
+
+
+    /* This currently happens only for NULLs, but could be extended. */
+
+    case BADCHAR_CMD:
+      done = synprot_error(L_smtp_syntax_error, 0, NULL,       /* Just logs */
+	US"NUL character(s) present (shown as '?')");
+      smtp_printf("501 NUL characters are not allowed in SMTP commands\r\n",
+		  FALSE);
+      break;
+
+
+    case BADSYN_CMD:
+    SYNC_FAILURE:
+      if (smtp_inend >= smtp_inbuffer + IN_BUFFER_SIZE)
+	smtp_inend = smtp_inbuffer + IN_BUFFER_SIZE - 1;
+      c = smtp_inend - smtp_inptr;
+      if (c > 150) c = 150;	/* limit logged amount */
+      smtp_inptr[c] = 0;
+      incomplete_transaction_log(US"sync failure");
+      log_write(0, LOG_MAIN|LOG_REJECT, "SMTP protocol synchronization error "
+	"(next input sent too soon: pipelining was%s advertised): "
+	"rejected \"%s\" %s next input=\"%s\"",
+	f.smtp_in_pipelining_advertised ? "" : " not",
+	smtp_cmd_buffer, host_and_ident(TRUE),
+	string_printing(smtp_inptr));
+      smtp_notquit_exit(US"synchronization-error", US"554",
+	US"SMTP synchronization error");
+      done = 1;   /* Pretend eof - drops connection */
+      break;
+
+
+    case TOO_MANY_NONMAIL_CMD:
+      s = smtp_cmd_buffer;
+      while (*s != 0 && !isspace(*s)) s++;
+      incomplete_transaction_log(US"too many non-mail commands");
+      log_write(0, LOG_MAIN|LOG_REJECT, "SMTP call from %s dropped: too many "
+	"nonmail commands (last was \"%.*s\")",  host_and_ident(FALSE),
+	(int)(s - smtp_cmd_buffer), smtp_cmd_buffer);
+      smtp_notquit_exit(US"bad-commands", US"554", US"Too many nonmail commands");
+      done = 1;   /* Pretend eof - drops connection */
+      break;
+
+#ifdef SUPPORT_PROXY
+    case PROXY_FAIL_IGNORE_CMD:
+      smtp_printf("503 Command refused, required Proxy negotiation failed\r\n", FALSE);
+      break;
+#endif
+
+    default:
+      if (unknown_command_count++ >= smtp_max_unknown_commands)
+	{
+	log_write(L_smtp_syntax_error, LOG_MAIN,
+	  "SMTP syntax error in \"%s\" %s %s",
+	  string_printing(smtp_cmd_buffer), host_and_ident(TRUE),
+	  US"unrecognized command");
+	incomplete_transaction_log(US"unrecognized command");
+	smtp_notquit_exit(US"bad-commands", US"500",
+	  US"Too many unrecognized commands");
+	done = 2;
+	log_write(0, LOG_MAIN|LOG_REJECT, "SMTP call from %s dropped: too many "
+	  "unrecognized commands (last was \"%s\")", host_and_ident(FALSE),
+	  string_printing(smtp_cmd_buffer));
+	}
+      else
+	done = synprot_error(L_smtp_syntax_error, 500, NULL,
+	  US"unrecognized command");
+      break;
+    }
+
+  /* This label is used by goto's inside loops that want to break out to
+  the end of the command-processing loop. */
+
+  COMMAND_LOOP:
+  last_was_rej_mail = was_rej_mail;     /* Remember some last commands for */
+  last_was_rcpt = was_rcpt;             /* protocol error handling */
+  }
+
+return done - 2;  /* Convert yield values */
+}
+
+
+
+gstring *
+authres_smtpauth(gstring * g)
+{
+if (!sender_host_authenticated)
+  return g;
+
+g = string_append(g, 2, US";\n\tauth=pass (", sender_host_auth_pubname);
+
+if (Ustrcmp(sender_host_auth_pubname, "tls") == 0)
+  g = authenticated_id
+    ? string_append(g, 2, US") x509.auth=", authenticated_id)
+    : string_cat(g, US") reason=x509.auth");
+else
+  g = authenticated_id
+    ? string_append(g, 2, US") smtp.auth=", authenticated_id)
+    : string_cat(g, US", no id saved)");
+
+if (authenticated_sender)
+  g = string_append(g, 2, US" smtp.mailfrom=", authenticated_sender);
+return g;
+}
+
+
+
+/* vi: aw ai sw=2
+*/
+/* End of smtp_in.c */