Adding upstream version 3.7.10.upstream/3.7.10

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

5 files changed, 2324 insertions, 0 deletions

diff --git a/src/tlsproxy/.indent.pro b/src/tlsproxy/.indent.pro
new file mode 120000
index 0000000..5c837ec
--- /dev/null
+++ b/src/tlsproxy/.indent.pro
@@ -0,0 +1 @@
+../../.indent.pro
\ No newline at end of file
diff --git a/src/tlsproxy/Makefile.in b/src/tlsproxy/Makefile.in
new file mode 100644
index 0000000..c72aa81
--- /dev/null
+++ b/src/tlsproxy/Makefile.in
@@ -0,0 +1,117 @@
+SHELL	= /bin/sh
+SRCS	= tlsproxy.c tlsproxy_state.c
+OBJS	= tlsproxy.o tlsproxy_state.o
+HDRS	= 
+TESTSRC	=
+DEFS	= -I. -I$(INC_DIR) -D$(SYSTYPE)
+CFLAGS	= $(DEBUG) $(OPT) $(DEFS)
+TESTPROG= 
+PROG	= tlsproxy
+INC_DIR = ../../include
+LIBS	= ../../lib/lib$(LIB_PREFIX)master$(LIB_SUFFIX) \
+	../../lib/lib$(LIB_PREFIX)tls$(LIB_SUFFIX) \
+	../../lib/lib$(LIB_PREFIX)dns$(LIB_SUFFIX) \
+	../../lib/lib$(LIB_PREFIX)global$(LIB_SUFFIX) \
+	../../lib/lib$(LIB_PREFIX)util$(LIB_SUFFIX)
+
+.c.o:;	$(CC) $(CFLAGS) -c $*.c
+
+$(PROG): $(OBJS) $(LIBS)
+	$(CC) $(CFLAGS) $(SHLIB_RPATH) -o $@ $(OBJS) $(LIBS) $(SYSLIBS)
+
+$(OBJS): ../../conf/makedefs.out
+
+Makefile: Makefile.in
+	cat ../../conf/makedefs.out $? >$@
+
+test:	$(TESTPROG)
+
+tests:	test
+
+root_tests:
+
+update: ../../libexec/$(PROG)
+
+../../libexec/$(PROG): $(PROG)
+	cp $(PROG) ../../libexec
+
+printfck: $(OBJS) $(PROG)
+	rm -rf printfck
+	mkdir printfck
+	sed '1,/^# do not edit/!d' Makefile >printfck/Makefile
+	set -e; for i in *.c; do printfck -f .printfck $$i >printfck/$$i; done
+	cd printfck; make "INC_DIR=../../../include" `cd ..; ls *.o`
+
+lint:
+	lint $(DEFS) $(SRCS) $(LINTFIX)
+
+clean:
+	rm -f *.o *core $(PROG) $(TESTPROG) junk 
+	rm -rf printfck
+
+tidy:	clean
+
+depend: $(MAKES)
+	(sed '1,/^# do not edit/!d' Makefile.in; \
+	set -e; for i in [a-z][a-z0-9]*.c; do \
+	    $(CC) -E $(DEFS) $(INCL) $$i | grep -v '[<>]' | sed -n -e '/^# *1 *"\([^"]*\)".*/{' \
+	    -e 's//'`echo $$i|sed 's/c$$/o/'`': \1/' \
+	    -e 's/o: \.\//o: /' -e p -e '}' ; \
+	done | LANG=C sort -u) | grep -v '[.][o][:][ ][/]' >$$$$ && mv $$$$ Makefile.in
+	@$(EXPORT) make -f Makefile.in Makefile 1>&2
+
+# do not edit below this line - it is generated by 'make depend'
+tlsproxy.o: ../../include/argv.h
+tlsproxy.o: ../../include/attr.h
+tlsproxy.o: ../../include/been_here.h
+tlsproxy.o: ../../include/check_arg.h
+tlsproxy.o: ../../include/dns.h
+tlsproxy.o: ../../include/events.h
+tlsproxy.o: ../../include/htable.h
+tlsproxy.o: ../../include/iostuff.h
+tlsproxy.o: ../../include/mail_conf.h
+tlsproxy.o: ../../include/mail_params.h
+tlsproxy.o: ../../include/mail_proto.h
+tlsproxy.o: ../../include/mail_server.h
+tlsproxy.o: ../../include/mail_version.h
+tlsproxy.o: ../../include/msg.h
+tlsproxy.o: ../../include/myaddrinfo.h
+tlsproxy.o: ../../include/mymalloc.h
+tlsproxy.o: ../../include/name_code.h
+tlsproxy.o: ../../include/name_mask.h
+tlsproxy.o: ../../include/nbbio.h
+tlsproxy.o: ../../include/nvtable.h
+tlsproxy.o: ../../include/sock_addr.h
+tlsproxy.o: ../../include/split_at.h
+tlsproxy.o: ../../include/sys_defs.h
+tlsproxy.o: ../../include/tls.h
+tlsproxy.o: ../../include/tls_proxy.h
+tlsproxy.o: ../../include/vbuf.h
+tlsproxy.o: ../../include/vstream.h
+tlsproxy.o: ../../include/vstring.h
+tlsproxy.o: tlsproxy.c
+tlsproxy.o: tlsproxy.h
+tlsproxy_state.o: ../../include/argv.h
+tlsproxy_state.o: ../../include/attr.h
+tlsproxy_state.o: ../../include/check_arg.h
+tlsproxy_state.o: ../../include/dns.h
+tlsproxy_state.o: ../../include/events.h
+tlsproxy_state.o: ../../include/htable.h
+tlsproxy_state.o: ../../include/mail_conf.h
+tlsproxy_state.o: ../../include/mail_server.h
+tlsproxy_state.o: ../../include/msg.h
+tlsproxy_state.o: ../../include/myaddrinfo.h
+tlsproxy_state.o: ../../include/mymalloc.h
+tlsproxy_state.o: ../../include/name_code.h
+tlsproxy_state.o: ../../include/name_mask.h
+tlsproxy_state.o: ../../include/nbbio.h
+tlsproxy_state.o: ../../include/nvtable.h
+tlsproxy_state.o: ../../include/sock_addr.h
+tlsproxy_state.o: ../../include/sys_defs.h
+tlsproxy_state.o: ../../include/tls.h
+tlsproxy_state.o: ../../include/tls_proxy.h
+tlsproxy_state.o: ../../include/vbuf.h
+tlsproxy_state.o: ../../include/vstream.h
+tlsproxy_state.o: ../../include/vstring.h
+tlsproxy_state.o: tlsproxy.h
+tlsproxy_state.o: tlsproxy_state.c
diff --git a/src/tlsproxy/tlsproxy.c b/src/tlsproxy/tlsproxy.c
new file mode 100644
index 0000000..ccb3804
--- /dev/null
+++ b/src/tlsproxy/tlsproxy.c
@@ -0,0 +1,1968 @@
+/*++
+/* NAME
+/*	tlsproxy 8
+/* SUMMARY
+/*	Postfix TLS proxy
+/* SYNOPSIS
+/*	\fBtlsproxy\fR [generic Postfix daemon options]
+/* DESCRIPTION
+/*	The \fBtlsproxy\fR(8) server implements a two-way TLS proxy. It
+/*	is used by the \fBpostscreen\fR(8) server to talk SMTP-over-TLS
+/*	with remote SMTP clients that are not allowlisted (including
+/*	clients whose allowlist status has expired), and by the
+/*	\fBsmtp\fR(8) client to support TLS connection reuse, but it
+/*	should also work for non-SMTP protocols.
+/*
+/*	Although one \fBtlsproxy\fR(8) process can serve multiple
+/*	sessions at the same time, it is a good idea to allow the
+/*	number of processes to increase with load, so that the
+/*	service remains responsive.
+/* PROTOCOL EXAMPLE
+/* .ad
+/* .fi
+/*	The example below concerns \fBpostscreen\fR(8). However,
+/*	the \fBtlsproxy\fR(8) server is agnostic of the application
+/*	protocol, and the example is easily adapted to other
+/*	applications.
+/*
+/*	After receiving a valid remote SMTP client STARTTLS command,
+/*	the \fBpostscreen\fR(8) server sends the remote SMTP client
+/*	endpoint string, the requested role (server), and the
+/*	requested timeout to \fBtlsproxy\fR(8).  \fBpostscreen\fR(8)
+/*	then receives a "TLS available" indication from \fBtlsproxy\fR(8).
+/*	If the TLS service is available, \fBpostscreen\fR(8) sends
+/*	the remote SMTP client file descriptor to \fBtlsproxy\fR(8),
+/*	and sends the plaintext 220 greeting to the remote SMTP
+/*	client.  This triggers TLS negotiations between the remote
+/*	SMTP client and \fBtlsproxy\fR(8).  Upon completion of the
+/*	TLS-level handshake, \fBtlsproxy\fR(8) translates between
+/*	plaintext from/to \fBpostscreen\fR(8) and ciphertext to/from
+/*	the remote SMTP client.
+/* SECURITY
+/* .ad
+/* .fi
+/*	The \fBtlsproxy\fR(8) server is moderately security-sensitive.
+/*	It talks to untrusted clients on the network. The process
+/*	can be run chrooted at fixed low privilege.
+/* DIAGNOSTICS
+/*	Problems and transactions are logged to \fBsyslogd\fR(8)
+/*	or \fBpostlogd\fR(8).
+/* CONFIGURATION PARAMETERS
+/* .ad
+/* .fi
+/*	Changes to \fBmain.cf\fR are not picked up automatically,
+/*	as \fBtlsproxy\fR(8) processes may run for a long time
+/*	depending on mail server load.  Use the command "\fBpostfix
+/*	reload\fR" to speed up a change.
+/*
+/*	The text below provides only a parameter summary. See
+/*	\fBpostconf\fR(5) for more details including examples.
+/* STARTTLS GLOBAL CONTROLS
+/* .ad
+/* .fi
+/*	The following settings are global and therefore cannot be
+/*	overruled by information specified in a \fBtlsproxy\fR(8)
+/*	client request.
+/* .IP "\fBtls_append_default_CA (no)\fR"
+/*	Append the system-supplied default Certification Authority
+/*	certificates to the ones specified with *_tls_CApath or *_tls_CAfile.
+/* .IP "\fBtls_daemon_random_bytes (32)\fR"
+/*	The number of pseudo-random bytes that an \fBsmtp\fR(8) or \fBsmtpd\fR(8)
+/*	process requests from the \fBtlsmgr\fR(8) server in order to seed its
+/*	internal pseudo random number generator (PRNG).
+/* .IP "\fBtls_high_cipherlist (see 'postconf -d' output)\fR"
+/*	The OpenSSL cipherlist for "high" grade ciphers.
+/* .IP "\fBtls_medium_cipherlist (see 'postconf -d' output)\fR"
+/*	The OpenSSL cipherlist for "medium" or higher grade ciphers.
+/* .IP "\fBtls_low_cipherlist (see 'postconf -d' output)\fR"
+/*	The OpenSSL cipherlist for "low" or higher grade ciphers.
+/* .IP "\fBtls_export_cipherlist (see 'postconf -d' output)\fR"
+/*	The OpenSSL cipherlist for "export" or higher grade ciphers.
+/* .IP "\fBtls_null_cipherlist (eNULL:!aNULL)\fR"
+/*	The OpenSSL cipherlist for "NULL" grade ciphers that provide
+/*	authentication without encryption.
+/* .IP "\fBtls_eecdh_strong_curve (prime256v1)\fR"
+/*	The elliptic curve used by the Postfix SMTP server for sensibly
+/*	strong
+/*	ephemeral ECDH key exchange.
+/* .IP "\fBtls_eecdh_ultra_curve (secp384r1)\fR"
+/*	The elliptic curve used by the Postfix SMTP server for maximally
+/*	strong
+/*	ephemeral ECDH key exchange.
+/* .IP "\fBtls_disable_workarounds (see 'postconf -d' output)\fR"
+/*	List or bit-mask of OpenSSL bug work-arounds to disable.
+/* .IP "\fBtls_preempt_cipherlist (no)\fR"
+/*	With SSLv3 and later, use the Postfix SMTP server's cipher
+/*	preference order instead of the remote client's cipher preference
+/*	order.
+/* .PP
+/*	Available in Postfix version 2.9 and later:
+/* .IP "\fBtls_legacy_public_key_fingerprints (no)\fR"
+/*	A temporary migration aid for sites that use certificate
+/*	\fIpublic-key\fR fingerprints with Postfix 2.9.0..2.9.5, which use
+/*	an incorrect algorithm.
+/* .PP
+/*	Available in Postfix version 2.11-3.1:
+/* .IP "\fBtls_dane_digest_agility (on)\fR"
+/*	Configure RFC7671 DANE TLSA digest algorithm agility.
+/* .IP "\fBtls_dane_trust_anchor_digest_enable (yes)\fR"
+/*	Enable support for RFC 6698 (DANE TLSA) DNS records that contain
+/*	digests of trust-anchors with certificate usage "2".
+/* .PP
+/*	Available in Postfix version 2.11 and later:
+/* .IP "\fBtlsmgr_service_name (tlsmgr)\fR"
+/*	The name of the \fBtlsmgr\fR(8) service entry in master.cf.
+/* .PP
+/*	Available in Postfix version 3.0 and later:
+/* .IP "\fBtls_session_ticket_cipher (Postfix >= 3.0: aes-256-cbc, Postfix < 3.0: aes-128-cbc)\fR"
+/*	Algorithm used to encrypt RFC5077 TLS session tickets.
+/* .IP "\fBopenssl_path (openssl)\fR"
+/*	The location of the OpenSSL command line program \fBopenssl\fR(1).
+/* .PP
+/*	Available in Postfix version 3.2 and later:
+/* .IP "\fBtls_eecdh_auto_curves (see 'postconf -d' output)\fR"
+/*	The prioritized list of elliptic curves supported by the Postfix
+/*	SMTP client and server.
+/* .PP
+/*	Available in Postfix version 3.4 and later:
+/* .IP "\fBtls_server_sni_maps (empty)\fR"
+/*	Optional lookup tables that map names received from remote SMTP
+/*	clients via the TLS Server Name Indication (SNI) extension to the
+/*	appropriate keys and certificate chains.
+/* .PP
+/*	Available in Postfix 3.5, 3.4.6, 3.3.5, 3.2.10, 3.1.13 and later:
+/* .IP "\fBtls_fast_shutdown_enable (yes)\fR"
+/*	A workaround for implementations that hang Postfix while shutting
+/*	down a TLS session, until Postfix times out.
+/* .PP
+/*	Available in Postfix 3.9, 3.8.1, 3.7.6, 3.6.10, 3.5.20 and later:
+/* .IP "\fBtls_config_file (default)\fR"
+/*	Optional configuration file with baseline OpenSSL settings.
+/* .IP "\fBtls_config_name (empty)\fR"
+/*	The application name passed by Postfix to OpenSSL library
+/*	initialization functions.
+/* STARTTLS SERVER CONTROLS
+/* .ad
+/* .fi
+/*	These settings are clones of Postfix SMTP server settings.
+/*	They allow \fBtlsproxy\fR(8) to load the same certificate
+/*	and private key information as the Postfix SMTP server,
+/*	before dropping privileges, so that the key files can be
+/*	kept read-only for root. These settings can currently not
+/*	be overruled by information in a \fBtlsproxy\fR(8) client
+/*	request, but that limitation may be removed in a future
+/*	version.
+/* .IP "\fBtlsproxy_tls_CAfile ($smtpd_tls_CAfile)\fR"
+/*	A file containing (PEM format) CA certificates of root CAs
+/*	trusted to sign either remote SMTP client certificates or intermediate
+/*	CA certificates.
+/* .IP "\fBtlsproxy_tls_CApath ($smtpd_tls_CApath)\fR"
+/*	A directory containing (PEM format) CA certificates of root CAs
+/*	trusted to sign either remote SMTP client certificates or intermediate
+/*	CA certificates.
+/* .IP "\fBtlsproxy_tls_always_issue_session_ids ($smtpd_tls_always_issue_session_ids)\fR"
+/*	Force the Postfix \fBtlsproxy\fR(8) server to issue a TLS session id,
+/*	even when TLS session caching is turned off.
+/* .IP "\fBtlsproxy_tls_ask_ccert ($smtpd_tls_ask_ccert)\fR"
+/*	Ask a remote SMTP client for a client certificate.
+/* .IP "\fBtlsproxy_tls_ccert_verifydepth ($smtpd_tls_ccert_verifydepth)\fR"
+/*	The verification depth for remote SMTP client certificates.
+/* .IP "\fBtlsproxy_tls_cert_file ($smtpd_tls_cert_file)\fR"
+/*	File with the Postfix \fBtlsproxy\fR(8) server RSA certificate in PEM
+/*	format.
+/* .IP "\fBtlsproxy_tls_ciphers ($smtpd_tls_ciphers)\fR"
+/*	The minimum TLS cipher grade that the Postfix \fBtlsproxy\fR(8) server
+/*	will use with opportunistic TLS encryption.
+/* .IP "\fBtlsproxy_tls_dcert_file ($smtpd_tls_dcert_file)\fR"
+/*	File with the Postfix \fBtlsproxy\fR(8) server DSA certificate in PEM
+/*	format.
+/* .IP "\fBtlsproxy_tls_dh1024_param_file ($smtpd_tls_dh1024_param_file)\fR"
+/*	File with DH parameters that the Postfix \fBtlsproxy\fR(8) server
+/*	should use with non-export EDH ciphers.
+/* .IP "\fBtlsproxy_tls_dh512_param_file ($smtpd_tls_dh512_param_file)\fR"
+/*	File with DH parameters that the Postfix \fBtlsproxy\fR(8) server
+/*	should use with export-grade EDH ciphers.
+/* .IP "\fBtlsproxy_tls_dkey_file ($smtpd_tls_dkey_file)\fR"
+/*	File with the Postfix \fBtlsproxy\fR(8) server DSA private key in PEM
+/*	format.
+/* .IP "\fBtlsproxy_tls_eccert_file ($smtpd_tls_eccert_file)\fR"
+/*	File with the Postfix \fBtlsproxy\fR(8) server ECDSA certificate in PEM
+/*	format.
+/* .IP "\fBtlsproxy_tls_eckey_file ($smtpd_tls_eckey_file)\fR"
+/*	File with the Postfix \fBtlsproxy\fR(8) server ECDSA private key in PEM
+/*	format.
+/* .IP "\fBtlsproxy_tls_eecdh_grade ($smtpd_tls_eecdh_grade)\fR"
+/*	The Postfix \fBtlsproxy\fR(8) server security grade for ephemeral
+/*	elliptic-curve Diffie-Hellman (EECDH) key exchange.
+/* .IP "\fBtlsproxy_tls_exclude_ciphers ($smtpd_tls_exclude_ciphers)\fR"
+/*	List of ciphers or cipher types to exclude from the \fBtlsproxy\fR(8)
+/*	server cipher list at all TLS security levels.
+/* .IP "\fBtlsproxy_tls_fingerprint_digest ($smtpd_tls_fingerprint_digest)\fR"
+/*	The message digest algorithm to construct remote SMTP
+/*	client-certificate
+/*	fingerprints.
+/* .IP "\fBtlsproxy_tls_key_file ($smtpd_tls_key_file)\fR"
+/*	File with the Postfix \fBtlsproxy\fR(8) server RSA private key in PEM
+/*	format.
+/* .IP "\fBtlsproxy_tls_loglevel ($smtpd_tls_loglevel)\fR"
+/*	Enable additional Postfix \fBtlsproxy\fR(8) server logging of TLS
+/*	activity.
+/* .IP "\fBtlsproxy_tls_mandatory_ciphers ($smtpd_tls_mandatory_ciphers)\fR"
+/*	The minimum TLS cipher grade that the Postfix \fBtlsproxy\fR(8) server
+/*	will use with mandatory TLS encryption.
+/* .IP "\fBtlsproxy_tls_mandatory_exclude_ciphers ($smtpd_tls_mandatory_exclude_ciphers)\fR"
+/*	Additional list of ciphers or cipher types to exclude from the
+/*	\fBtlsproxy\fR(8) server cipher list at mandatory TLS security levels.
+/* .IP "\fBtlsproxy_tls_mandatory_protocols ($smtpd_tls_mandatory_protocols)\fR"
+/*	The SSL/TLS protocols accepted by the Postfix \fBtlsproxy\fR(8) server
+/*	with mandatory TLS encryption.
+/* .IP "\fBtlsproxy_tls_protocols ($smtpd_tls_protocols)\fR"
+/*	List of TLS protocols that the Postfix \fBtlsproxy\fR(8) server will
+/*	exclude or include with opportunistic TLS encryption.
+/* .IP "\fBtlsproxy_tls_req_ccert ($smtpd_tls_req_ccert)\fR"
+/*	With mandatory TLS encryption, require a trusted remote SMTP
+/*	client certificate in order to allow TLS connections to proceed.
+/* .IP "\fBtlsproxy_tls_security_level ($smtpd_tls_security_level)\fR"
+/*	The SMTP TLS security level for the Postfix \fBtlsproxy\fR(8) server;
+/*	when a non-empty value is specified, this overrides the obsolete
+/*	parameters smtpd_use_tls and smtpd_enforce_tls.
+/* .IP "\fBtlsproxy_tls_chain_files ($smtpd_tls_chain_files)\fR"
+/*	Files with the Postfix \fBtlsproxy\fR(8) server keys and certificate
+/*	chains in PEM format.
+/* STARTTLS CLIENT CONTROLS
+/* .ad
+/* .fi
+/*	These settings are clones of Postfix SMTP client settings.
+/*	They allow \fBtlsproxy\fR(8) to load the same certificate
+/*	and private key information as the Postfix SMTP client,
+/*	before dropping privileges, so that the key files can be
+/*	kept read-only for root. Some settings may be overruled by
+/*	information in a \fBtlsproxy\fR(8) client request.
+/* .PP
+/*	Available in Postfix version 3.4 and later:
+/* .IP "\fBtlsproxy_client_CAfile ($smtp_tls_CAfile)\fR"
+/*	A file containing CA certificates of root CAs trusted to sign
+/*	either remote TLS server certificates or intermediate CA certificates.
+/* .IP "\fBtlsproxy_client_CApath ($smtp_tls_CApath)\fR"
+/*	Directory with PEM format Certification Authority certificates
+/*	that the Postfix \fBtlsproxy\fR(8) client uses to verify a remote TLS
+/*	server certificate.
+/* .IP "\fBtlsproxy_client_chain_files ($smtp_tls_chain_files)\fR"
+/*	Files with the Postfix \fBtlsproxy\fR(8) client keys and certificate
+/*	chains in PEM format.
+/* .IP "\fBtlsproxy_client_cert_file ($smtp_tls_cert_file)\fR"
+/*	File with the Postfix \fBtlsproxy\fR(8) client RSA certificate in PEM
+/*	format.
+/* .IP "\fBtlsproxy_client_key_file ($smtp_tls_key_file)\fR"
+/*	File with the Postfix \fBtlsproxy\fR(8) client RSA private key in PEM
+/*	format.
+/* .IP "\fBtlsproxy_client_dcert_file ($smtp_tls_dcert_file)\fR"
+/*	File with the Postfix \fBtlsproxy\fR(8) client DSA certificate in PEM
+/*	format.
+/* .IP "\fBtlsproxy_client_dkey_file ($smtp_tls_dkey_file)\fR"
+/*	File with the Postfix \fBtlsproxy\fR(8) client DSA private key in PEM
+/*	format.
+/* .IP "\fBtlsproxy_client_eccert_file ($smtp_tls_eccert_file)\fR"
+/*	File with the Postfix \fBtlsproxy\fR(8) client ECDSA certificate in PEM
+/*	format.
+/* .IP "\fBtlsproxy_client_eckey_file ($smtp_tls_eckey_file)\fR"
+/*	File with the Postfix \fBtlsproxy\fR(8) client ECDSA private key in PEM
+/*	format.
+/* .IP "\fBtlsproxy_client_fingerprint_digest ($smtp_tls_fingerprint_digest)\fR"
+/*	The message digest algorithm used to construct remote TLS server
+/*	certificate fingerprints.
+/* .IP "\fBtlsproxy_client_loglevel ($smtp_tls_loglevel)\fR"
+/*	Enable additional Postfix \fBtlsproxy\fR(8) client logging of TLS
+/*	activity.
+/* .IP "\fBtlsproxy_client_loglevel_parameter (smtp_tls_loglevel)\fR"
+/*	The name of the parameter that provides the tlsproxy_client_loglevel
+/*	value.
+/* .IP "\fBtlsproxy_client_scert_verifydepth ($smtp_tls_scert_verifydepth)\fR"
+/*	The verification depth for remote TLS server certificates.
+/* .IP "\fBtlsproxy_client_use_tls ($smtp_use_tls)\fR"
+/*	Opportunistic mode: use TLS when a remote server announces TLS
+/*	support.
+/* .IP "\fBtlsproxy_client_enforce_tls ($smtp_enforce_tls)\fR"
+/*	Enforcement mode: require that SMTP servers use TLS encryption.
+/* .IP "\fBtlsproxy_client_per_site ($smtp_tls_per_site)\fR"
+/*	Optional lookup tables with the Postfix \fBtlsproxy\fR(8) client TLS
+/*	usage policy by next-hop destination and by remote TLS server
+/*	hostname.
+/* .PP
+/*	Available in Postfix version 3.4-3.6:
+/* .IP "\fBtlsproxy_client_level ($smtp_tls_security_level)\fR"
+/*	The default TLS security level for the Postfix \fBtlsproxy\fR(8)
+/*	client.
+/* .IP "\fBtlsproxy_client_policy ($smtp_tls_policy_maps)\fR"
+/*	Optional lookup tables with the Postfix \fBtlsproxy\fR(8) client TLS
+/*	security policy by next-hop destination.
+/* .PP
+/*	Available in Postfix version 3.7 and later:
+/* .IP "\fBtlsproxy_client_security_level ($smtp_tls_security_level)\fR"
+/*	The default TLS security level for the Postfix \fBtlsproxy\fR(8)
+/*	client.
+/* .IP "\fBtlsproxy_client_policy_maps ($smtp_tls_policy_maps)\fR"
+/*	Optional lookup tables with the Postfix \fBtlsproxy\fR(8) client TLS
+/*	security policy by next-hop destination.
+/* OBSOLETE STARTTLS SUPPORT CONTROLS
+/* .ad
+/* .fi
+/*	These parameters are supported for compatibility with
+/*	\fBsmtpd\fR(8) legacy parameters.
+/* .IP "\fBtlsproxy_use_tls ($smtpd_use_tls)\fR"
+/*	Opportunistic TLS: announce STARTTLS support to remote SMTP clients,
+/*	but do not require that clients use TLS encryption.
+/* .IP "\fBtlsproxy_enforce_tls ($smtpd_enforce_tls)\fR"
+/*	Mandatory TLS: announce STARTTLS support to remote SMTP clients, and
+/*	require that clients use TLS encryption.
+/* .IP "\fBtlsproxy_client_use_tls ($smtp_use_tls)\fR"
+/*	Opportunistic mode: use TLS when a remote server announces TLS
+/*	support.
+/* .IP "\fBtlsproxy_client_enforce_tls ($smtp_enforce_tls)\fR"
+/*	Enforcement mode: require that SMTP servers use TLS encryption.
+/* RESOURCE CONTROLS
+/* .ad
+/* .fi
+/* .IP "\fBtlsproxy_watchdog_timeout (10s)\fR"
+/*	How much time a \fBtlsproxy\fR(8) process may take to process local
+/*	or remote I/O before it is terminated by a built-in watchdog timer.
+/* MISCELLANEOUS CONTROLS
+/* .ad
+/* .fi
+/* .IP "\fBconfig_directory (see 'postconf -d' output)\fR"
+/*	The default location of the Postfix main.cf and master.cf
+/*	configuration files.
+/* .IP "\fBprocess_id (read-only)\fR"
+/*	The process ID of a Postfix command or daemon process.
+/* .IP "\fBprocess_name (read-only)\fR"
+/*	The process name of a Postfix command or daemon process.
+/* .IP "\fBsyslog_facility (mail)\fR"
+/*	The syslog facility of Postfix logging.
+/* .IP "\fBsyslog_name (see 'postconf -d' output)\fR"
+/*	A prefix that is prepended to the process name in syslog
+/*	records, so that, for example, "smtpd" becomes "prefix/smtpd".
+/* .PP
+/*	Available in Postfix 3.3 and later:
+/* .IP "\fBservice_name (read-only)\fR"
+/*	The master.cf service name of a Postfix daemon process.
+/* SEE ALSO
+/*	postscreen(8), Postfix zombie blocker
+/*	smtpd(8), Postfix SMTP server
+/*	postconf(5), configuration parameters
+/*	postlogd(8), Postfix logging
+/*	syslogd(8), system logging
+/* LICENSE
+/* .ad
+/* .fi
+/*	The Secure Mailer license must be distributed with this software.
+/* HISTORY
+/* .ad
+/* .fi
+/*	This service was introduced with Postfix version 2.8.
+/* AUTHOR(S)
+/*	Wietse Venema
+/*	IBM T.J. Watson Research
+/*	P.O. Box 704
+/*	Yorktown Heights, NY 10598, USA
+/*
+/*	Wietse Venema
+/*	Google, Inc.
+/*	111 8th Avenue
+/*	New York, NY 10011, USA
+/*--*/
+
+ /*
+  * System library.
+  */
+#include <sys_defs.h>
+#include <errno.h>
+
+#ifdef STRCASECMP_IN_STRINGS_H
+#include <strings.h>
+#endif
+
+ /*
+  * Utility library.
+  */
+#include <msg.h>
+#include <vstream.h>
+#include <iostuff.h>
+#include <nbbio.h>
+#include <mymalloc.h>
+#include <split_at.h>
+
+ /*
+  * Global library.
+  */
+#include <been_here.h>
+#include <mail_proto.h>
+#include <mail_params.h>
+#include <mail_conf.h>
+#include <mail_version.h>
+
+ /*
+  * Master library.
+  */
+#include <mail_server.h>
+
+ /*
+  * TLS library.
+  */
+#ifdef USE_TLS
+#define TLS_INTERNAL			/* XXX */
+#include <tls.h>
+#include <tls_proxy.h>
+
+ /*
+  * Application-specific.
+  */
+#include <tlsproxy.h>
+
+ /*
+  * Tunable parameters. We define our clones of the smtpd(8) parameters to
+  * avoid any confusion about which parameters are used by this program.
+  */
+int     var_smtpd_tls_ccert_vd;
+char   *var_smtpd_tls_loglevel;
+bool    var_smtpd_use_tls;
+bool    var_smtpd_enforce_tls;
+bool    var_smtpd_tls_ask_ccert;
+bool    var_smtpd_tls_req_ccert;
+bool    var_smtpd_tls_set_sessid;
+char   *var_smtpd_relay_ccerts;
+char   *var_smtpd_tls_chain_files;
+char   *var_smtpd_tls_cert_file;
+char   *var_smtpd_tls_key_file;
+char   *var_smtpd_tls_dcert_file;
+char   *var_smtpd_tls_dkey_file;
+char   *var_smtpd_tls_eccert_file;
+char   *var_smtpd_tls_eckey_file;
+char   *var_smtpd_tls_CAfile;
+char   *var_smtpd_tls_CApath;
+char   *var_smtpd_tls_ciph;
+char   *var_smtpd_tls_mand_ciph;
+char   *var_smtpd_tls_excl_ciph;
+char   *var_smtpd_tls_mand_excl;
+char   *var_smtpd_tls_proto;
+char   *var_smtpd_tls_mand_proto;
+char   *var_smtpd_tls_dh512_param_file;
+char   *var_smtpd_tls_dh1024_param_file;
+char   *var_smtpd_tls_eecdh;
+char   *var_smtpd_tls_fpt_dgst;
+char   *var_smtpd_tls_level;
+
+int     var_tlsp_tls_ccert_vd;
+char   *var_tlsp_tls_loglevel;
+bool    var_tlsp_use_tls;
+bool    var_tlsp_enforce_tls;
+bool    var_tlsp_tls_ask_ccert;
+bool    var_tlsp_tls_req_ccert;
+bool    var_tlsp_tls_set_sessid;
+char   *var_tlsp_tls_chain_files;
+char   *var_tlsp_tls_cert_file;
+char   *var_tlsp_tls_key_file;
+char   *var_tlsp_tls_dcert_file;
+char   *var_tlsp_tls_dkey_file;
+char   *var_tlsp_tls_eccert_file;
+char   *var_tlsp_tls_eckey_file;
+char   *var_tlsp_tls_CAfile;
+char   *var_tlsp_tls_CApath;
+char   *var_tlsp_tls_ciph;
+char   *var_tlsp_tls_mand_ciph;
+char   *var_tlsp_tls_excl_ciph;
+char   *var_tlsp_tls_mand_excl;
+char   *var_tlsp_tls_proto;
+char   *var_tlsp_tls_mand_proto;
+char   *var_tlsp_tls_dh512_param_file;
+char   *var_tlsp_tls_dh1024_param_file;
+char   *var_tlsp_tls_eecdh;
+char   *var_tlsp_tls_fpt_dgst;
+char   *var_tlsp_tls_level;
+
+int     var_tlsp_watchdog;
+
+ /*
+  * Defaults for tlsp_clnt_*.
+  */
+char   *var_smtp_tls_loglevel;
+int     var_smtp_tls_scert_vd;
+char   *var_smtp_tls_chain_files;
+char   *var_smtp_tls_cert_file;
+char   *var_smtp_tls_key_file;
+char   *var_smtp_tls_dcert_file;
+char   *var_smtp_tls_dkey_file;
+char   *var_smtp_tls_eccert_file;
+char   *var_smtp_tls_eckey_file;
+char   *var_smtp_tls_CAfile;
+char   *var_smtp_tls_CApath;
+char   *var_smtp_tls_fpt_dgst;
+char   *var_smtp_tls_level;
+bool    var_smtp_use_tls;
+bool    var_smtp_enforce_tls;
+char   *var_smtp_tls_per_site;
+char   *var_smtp_tls_policy;
+
+char   *var_tlsp_clnt_loglevel;
+char   *var_tlsp_clnt_logparam;
+int     var_tlsp_clnt_scert_vd;
+char   *var_tlsp_clnt_chain_files;
+char   *var_tlsp_clnt_cert_file;
+char   *var_tlsp_clnt_key_file;
+char   *var_tlsp_clnt_dcert_file;
+char   *var_tlsp_clnt_dkey_file;
+char   *var_tlsp_clnt_eccert_file;
+char   *var_tlsp_clnt_eckey_file;
+char   *var_tlsp_clnt_CAfile;
+char   *var_tlsp_clnt_CApath;
+char   *var_tlsp_clnt_fpt_dgst;
+char   *var_tlsp_clnt_level;
+bool    var_tlsp_clnt_use_tls;
+bool    var_tlsp_clnt_enforce_tls;
+char   *var_tlsp_clnt_per_site;
+char   *var_tlsp_clnt_policy;
+
+ /*
+  * TLS per-process status.
+  */
+static TLS_APPL_STATE *tlsp_server_ctx;
+static bool tlsp_pre_jail_done;
+static int ask_client_cert;
+static char *tlsp_pre_jail_client_param_key;	/* pre-jail global params */
+static char *tlsp_pre_jail_client_init_key;	/* pre-jail init props */
+
+ /*
+  * TLS per-client status.
+  */
+static HTABLE *tlsp_client_app_cache;	/* per-client init props */
+static BH_TABLE *tlsp_params_mismatch_filter;	/* per-client nag filter */
+
+ /*
+  * Error handling: if a function detects an error, then that function is
+  * responsible for destroying TLSP_STATE. Exceptions to this principle are
+  * indicated in the code.
+  */
+
+ /*
+  * Internal status API.
+  */
+#define TLSP_STAT_OK	0
+#define TLSP_STAT_ERR	(-1)
+
+ /*
+  * SLMs.
+  */
+#define STR(x)	vstring_str(x)
+#define LEN(x)	VSTRING_LEN(x)
+
+ /*
+  * The code that implements the TLS engine looks simpler than expected. That
+  * is the result of a great deal of effort, mainly in design and analysis.
+  * 
+  * The initial use case was to provide TLS support for postscreen(8).
+  * 
+  * By design, postscreen(8) is an event-driven server that must scale up to a
+  * large number of clients. This means that postscreen(8) must avoid doing
+  * CPU-intensive operations such as those in OpenSSL.
+  * 
+  * tlsproxy(8) runs the OpenSSL code on behalf of postscreen(8), translating
+  * plaintext SMTP messages from postscreen(8) into SMTP-over-TLS messages to
+  * the remote SMTP client, and vice versa. As long as postscreen(8) does not
+  * receive email messages, the cost of doing TLS operations will be modest.
+  * 
+  * Like postscreen(8), one tlsproxy(8) process services multiple remote SMTP
+  * clients. Unlike postscreen(8), there can be more than one tlsproxy(8)
+  * process, although their number is meant to be much smaller than the
+  * number of remote SMTP clients that talk TLS.
+  * 
+  * As with postscreen(8), all I/O must be event-driven: encrypted traffic
+  * between tlsproxy(8) and remote SMTP clients, and plaintext traffic
+  * between tlsproxy(8) and postscreen(8). Event-driven plaintext I/O is
+  * straightforward enough that it could be abstracted away with the nbbio(3)
+  * module.
+  * 
+  * The event-driven TLS I/O implementation is founded on on-line OpenSSL
+  * documentation, supplemented by statements from OpenSSL developers on
+  * public mailing lists. After some field experience with this code, we may
+  * be able to factor it out as a library module, like nbbio(3), that can
+  * become part of the TLS library.
+  * 
+  * Later in the life cycle, tlsproxy(8) has also become an enabler for TLS
+  * connection reuse across different SMTP client processes.
+  */
+
+static void tlsp_ciphertext_event(int, void *);
+
+#define TLSP_INIT_TIMEOUT	100
+
+static void tlsp_plaintext_event(int event, void *context);
+
+/* tlsp_drain - delayed exit after "postfix reload" */
+
+static void tlsp_drain(char *unused_service, char **unused_argv)
+{
+    int     count;
+
+    /*
+     * After "postfix reload", complete work-in-progress in the background,
+     * instead of dropping already-accepted connections on the floor.
+     * 
+     * All error retry counts shall be limited. Instead of blocking here, we
+     * could retry failed fork() operations in the event call-back routines,
+     * but we don't need perfection. The host system is severely overloaded
+     * and service levels are already way down.
+     */
+    for (count = 0; /* see below */ ; count++) {
+	if (count >= 5) {
+	    msg_fatal("fork: %m");
+	} else if (event_server_drain() != 0) {
+	    msg_warn("fork: %m");
+	    sleep(1);
+	    continue;
+	} else {
+	    return;
+	}
+    }
+}
+
+/* tlsp_eval_tls_error - translate TLS "error" result into action */
+
+static int tlsp_eval_tls_error(TLSP_STATE *state, int err)
+{
+    int     ciphertext_fd = state->ciphertext_fd;
+
+    /*
+     * The ciphertext file descriptor is in non-blocking mode, meaning that
+     * each SSL_accept/connect/read/write/shutdown request may return an
+     * "error" indication that it needs to read or write more ciphertext. The
+     * purpose of this routine is to translate those "error" indications into
+     * the appropriate read/write/timeout event requests.
+     */
+    switch (err) {
+
+	/*
+	 * No error means a successful SSL_accept/connect/shutdown request or
+	 * sequence of SSL_read/write requests. Disable read/write events on
+	 * the ciphertext stream. Keep the ciphertext stream timer alive as a
+	 * safety mechanism for the case that the plaintext pseudothreads get
+	 * stuck.
+	 */
+    case SSL_ERROR_NONE:
+	if (state->ssl_last_err != SSL_ERROR_NONE) {
+	    event_disable_readwrite(ciphertext_fd);
+	    event_request_timer(tlsp_ciphertext_event, (void *) state,
+				state->timeout);
+	    state->ssl_last_err = SSL_ERROR_NONE;
+	}
+	return (TLSP_STAT_OK);
+
+	/*
+	 * The TLS engine wants to write to the network. Turn on
+	 * write/timeout events on the ciphertext stream.
+	 */
+    case SSL_ERROR_WANT_WRITE:
+	if (state->ssl_last_err == SSL_ERROR_WANT_READ)
+	    event_disable_readwrite(ciphertext_fd);
+	if (state->ssl_last_err != SSL_ERROR_WANT_WRITE) {
+	    event_enable_write(ciphertext_fd, tlsp_ciphertext_event,
+			       (void *) state);
+	    state->ssl_last_err = SSL_ERROR_WANT_WRITE;
+	}
+	event_request_timer(tlsp_ciphertext_event, (void *) state,
+			    state->timeout);
+	return (TLSP_STAT_OK);
+
+	/*
+	 * The TLS engine wants to read from the network. Turn on
+	 * read/timeout events on the ciphertext stream.
+	 */
+    case SSL_ERROR_WANT_READ:
+	if (state->ssl_last_err == SSL_ERROR_WANT_WRITE)
+	    event_disable_readwrite(ciphertext_fd);
+	if (state->ssl_last_err != SSL_ERROR_WANT_READ) {
+	    event_enable_read(ciphertext_fd, tlsp_ciphertext_event,
+			      (void *) state);
+	    state->ssl_last_err = SSL_ERROR_WANT_READ;
+	}
+	event_request_timer(tlsp_ciphertext_event, (void *) state,
+			    state->timeout);
+	return (TLSP_STAT_OK);
+
+	/*
+	 * Some error. Self-destruct. This automagically cleans up all
+	 * pending read/write and timeout event requests, making state a
+	 * dangling pointer.
+	 */
+    case SSL_ERROR_SSL:
+	tls_print_errors();
+	/* FALLTHROUGH */
+    default:
+
+	/*
+	 * Allow buffered-up plaintext output to trickle out. Permanently
+	 * disable read/write activity on the ciphertext stream, so that this
+	 * function will no longer be called. Keep the ciphertext stream
+	 * timer alive as a safety mechanism for the case that the plaintext
+	 * pseudothreads get stuck. Return into tlsp_strategy(), which will
+	 * enable plaintext write events.
+	 */
+#define TLSP_CAN_TRICKLE_OUT_PLAINTEXT(buf) \
+	((buf) && !NBBIO_ERROR_FLAGS(buf) && NBBIO_WRITE_PEND(buf))
+
+	if (TLSP_CAN_TRICKLE_OUT_PLAINTEXT(state->plaintext_buf)) {
+	    event_disable_readwrite(ciphertext_fd);
+	    event_request_timer(tlsp_ciphertext_event, (void *) state,
+				state->timeout);
+	    state->flags |= TLSP_FLAG_NO_MORE_CIPHERTEXT_IO;
+	    return (TLSP_STAT_OK);
+	}
+	tlsp_state_free(state);
+	return (TLSP_STAT_ERR);
+    }
+}
+
+/* tlsp_post_handshake - post-handshake processing */
+
+static int tlsp_post_handshake(TLSP_STATE *state)
+{
+
+    /*
+     * Do not assume that tls_server_post_accept() and
+     * tls_client_post_connect() will always succeed.
+     */
+    if (state->is_server_role)
+	state->tls_context = tls_server_post_accept(state->tls_context);
+    else
+	state->tls_context = tls_client_post_connect(state->tls_context,
+						 state->client_start_props);
+    if (state->tls_context == 0) {
+	tlsp_state_free(state);
+	return (TLSP_STAT_ERR);
+    }
+
+    /*
+     * Report TLS handshake results to the tlsproxy client.
+     * 
+     * Security: this sends internal data over the same local plaintext stream
+     * that will also be used for sending decrypted remote content from an
+     * arbitrary remote peer. For this reason we enable decrypted I/O only
+     * after reporting the TLS handshake results. The Postfix attribute
+     * protocol is robust enough that an attacker cannot append content.
+     */
+    if ((state->req_flags & TLS_PROXY_FLAG_SEND_CONTEXT) != 0
+	&& (attr_print(state->plaintext_stream, ATTR_FLAG_NONE,
+		       SEND_ATTR_FUNC(tls_proxy_context_print,
+				      (void *) state->tls_context),
+		       ATTR_TYPE_END) != 0
+	    || vstream_fflush(state->plaintext_stream) != 0)) {
+	msg_warn("cannot send TLS context: %m");
+	tlsp_state_free(state);
+	return (TLSP_STAT_ERR);
+    }
+
+    /*
+     * Initialize plaintext-related session state. Once we have this behind
+     * us, the TLSP_STATE destructor will automagically clean up requests for
+     * plaintext read/write/timeout events, which makes error recovery
+     * easier.
+     */
+    state->plaintext_buf =
+	nbbio_create(vstream_fileno(state->plaintext_stream),
+		     VSTREAM_BUFSIZE, state->server_id,
+		     tlsp_plaintext_event,
+		     (void *) state);
+    return (TLSP_STAT_OK);
+}
+
+/* tlsp_strategy - decide what to read or write next. */
+
+static void tlsp_strategy(TLSP_STATE *state)
+{
+    TLS_SESS_STATE *tls_context = state->tls_context;
+    NBBIO  *plaintext_buf;
+    int     ssl_stat;
+    int     ssl_read_err;
+    int     ssl_write_err;
+    int     handshake_err;
+
+    /*
+     * This function is called after every ciphertext or plaintext event, to
+     * schedule new ciphertext or plaintext I/O.
+     */
+
+    /*
+     * Try to make an SSL I/O request. If this fails with SSL_ERROR_WANT_READ
+     * or SSL_ERROR_WANT_WRITE, enable ciphertext read or write events, and
+     * retry the SSL I/O request in a later tlsp_strategy() call.
+     */
+    if ((state->flags & TLSP_FLAG_NO_MORE_CIPHERTEXT_IO) == 0) {
+
+	/*
+	 * Do not enable plain-text I/O before completing the TLS handshake.
+	 * Otherwise the remote peer can prepend plaintext to the optional
+	 * TLS_SESS_STATE object.
+	 */
+	if (state->flags & TLSP_FLAG_DO_HANDSHAKE) {
+	    state->timeout = state->handshake_timeout;
+	    ERR_clear_error();
+	    if (state->is_server_role)
+		ssl_stat = SSL_accept(tls_context->con);
+	    else
+		ssl_stat = SSL_connect(tls_context->con);
+	    if (ssl_stat != 1) {
+		handshake_err = SSL_get_error(tls_context->con, ssl_stat);
+		tlsp_eval_tls_error(state, handshake_err);
+		/* At this point, state could be a dangling pointer. */
+		return;
+	    }
+	    state->flags &= ~TLSP_FLAG_DO_HANDSHAKE;
+	    state->timeout = state->session_timeout;
+	    if (tlsp_post_handshake(state) != TLSP_STAT_OK) {
+		/* At this point, state is a dangling pointer. */
+		return;
+	    }
+	}
+
+	/*
+	 * Shutdown and self-destruct after NBBIO error. This automagically
+	 * cleans up all pending read/write and timeout event requests.
+	 * Before shutting down TLS, we stop all plain-text I/O events but
+	 * keep the NBBIO error flags.
+	 */
+	plaintext_buf = state->plaintext_buf;
+	if (NBBIO_ERROR_FLAGS(plaintext_buf)) {
+	    if (NBBIO_ACTIVE_FLAGS(plaintext_buf))
+		nbbio_disable_readwrite(state->plaintext_buf);
+	    ERR_clear_error();
+	    if (!SSL_in_init(tls_context->con)
+		&& (ssl_stat = SSL_shutdown(tls_context->con)) < 0) {
+		handshake_err = SSL_get_error(tls_context->con, ssl_stat);
+		tlsp_eval_tls_error(state, handshake_err);
+		/* At this point, state could be a dangling pointer. */
+		return;
+	    }
+	    tlsp_state_free(state);
+	    return;
+	}
+
+	/*
+	 * Try to move data from the plaintext input buffer to the TLS
+	 * engine.
+	 * 
+	 * XXX We're supposed to repeat the exact same SSL_write() call
+	 * arguments after an SSL_ERROR_WANT_READ or SSL_ERROR_WANT_WRITE
+	 * result. Rumor has it that this is because each SSL_write() call
+	 * reads from the buffer incrementally, and returns > 0 only after
+	 * the final byte is processed. Rumor also has it that setting
+	 * SSL_MODE_ENABLE_PARTIAL_WRITE and
+	 * SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER voids this requirement, and
+	 * that repeating the request with an increased request size is OK.
+	 * Unfortunately all this is not or poorly documented, and one has to
+	 * rely on statements from OpenSSL developers in public mailing
+	 * archives.
+	 */
+	ssl_write_err = SSL_ERROR_NONE;
+	while (NBBIO_READ_PEND(plaintext_buf) > 0) {
+	    ERR_clear_error();
+	    ssl_stat = SSL_write(tls_context->con, NBBIO_READ_BUF(plaintext_buf),
+				 NBBIO_READ_PEND(plaintext_buf));
+	    ssl_write_err = SSL_get_error(tls_context->con, ssl_stat);
+	    if (ssl_write_err != SSL_ERROR_NONE)
+		break;
+	    /* Allow the plaintext pseudothread to read more data. */
+	    NBBIO_READ_PEND(plaintext_buf) -= ssl_stat;
+	    if (NBBIO_READ_PEND(plaintext_buf) > 0)
+		memmove(NBBIO_READ_BUF(plaintext_buf),
+			NBBIO_READ_BUF(plaintext_buf) + ssl_stat,
+			NBBIO_READ_PEND(plaintext_buf));
+	}
+
+	/*
+	 * Try to move data from the TLS engine to the plaintext output
+	 * buffer. Note: data may arrive as a side effect of calling
+	 * SSL_write(), therefore we call SSL_read() after calling
+	 * SSL_write().
+	 * 
+	 * XXX We're supposed to repeat the exact same SSL_read() call arguments
+	 * after an SSL_ERROR_WANT_READ or SSL_ERROR_WANT_WRITE result. This
+	 * supposedly means that our plaintext writer must not memmove() the
+	 * plaintext output buffer until after the SSL_read() call succeeds.
+	 * For now I'll ignore this, because 1) SSL_read() is documented to
+	 * return the bytes available, instead of returning > 0 only after
+	 * the entire buffer is processed like SSL_write() does; and 2) there
+	 * is no "read" equivalent of the SSL_R_BAD_WRITE_RETRY,
+	 * SSL_MODE_ENABLE_PARTIAL_WRITE or
+	 * SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER features.
+	 */
+	ssl_read_err = SSL_ERROR_NONE;
+	while (NBBIO_WRITE_PEND(state->plaintext_buf) < NBBIO_BUFSIZE(plaintext_buf)) {
+	    ERR_clear_error();
+	    ssl_stat = SSL_read(tls_context->con,
+				NBBIO_WRITE_BUF(plaintext_buf)
+				+ NBBIO_WRITE_PEND(state->plaintext_buf),
+				NBBIO_BUFSIZE(plaintext_buf)
+				- NBBIO_WRITE_PEND(state->plaintext_buf));
+	    ssl_read_err = SSL_get_error(tls_context->con, ssl_stat);
+	    if (ssl_read_err != SSL_ERROR_NONE)
+		break;
+	    NBBIO_WRITE_PEND(plaintext_buf) += ssl_stat;
+	}
+
+	/*
+	 * Try to enable/disable ciphertext read/write events. If SSL_write()
+	 * was satisfied, see if SSL_read() wants to do some work. In case of
+	 * an unrecoverable error, this automagically destroys the session
+	 * state after cleaning up all pending read/write and timeout event
+	 * requests.
+	 */
+	if (tlsp_eval_tls_error(state, ssl_write_err != SSL_ERROR_NONE ?
+				ssl_write_err : ssl_read_err) < 0)
+	    /* At this point, state is a dangling pointer. */
+	    return;
+    }
+
+    /*
+     * Destroy state when the ciphertext I/O was permanently disabled and we
+     * can no longer trickle out plaintext.
+     */
+    else {
+	plaintext_buf = state->plaintext_buf;
+	if (!TLSP_CAN_TRICKLE_OUT_PLAINTEXT(plaintext_buf)) {
+	    tlsp_state_free(state);
+	    return;
+	}
+    }
+
+    /*
+     * Try to enable/disable plaintext read/write events. Basically, if we
+     * have nothing to write to the plaintext stream, see if there is
+     * something to read. If the write buffer is empty and the read buffer is
+     * full, suspend plaintext I/O until conditions change (but keep the
+     * timer active, as a safety mechanism in case ciphertext I/O gets
+     * stuck).
+     * 
+     * XXX In theory, if the ciphertext peer keeps writing fast enough then we
+     * would never read from the plaintext stream and cause the latter to
+     * block. In practice, postscreen(8) limits the number of client
+     * commands, and thus postscreen(8)'s output will fit in a kernel buffer.
+     * A remote SMTP server is not supposed to flood the local SMTP client
+     * with massive replies; if it does, then the local SMTP client should
+     * deal with it.
+     */
+    if (NBBIO_WRITE_PEND(plaintext_buf) > 0) {
+	if (NBBIO_ACTIVE_FLAGS(plaintext_buf) & NBBIO_FLAG_READ)
+	    nbbio_disable_readwrite(plaintext_buf);
+	nbbio_enable_write(plaintext_buf, state->timeout);
+    } else if (NBBIO_READ_PEND(plaintext_buf) < NBBIO_BUFSIZE(plaintext_buf)) {
+	if (NBBIO_ACTIVE_FLAGS(plaintext_buf) & NBBIO_FLAG_WRITE)
+	    nbbio_disable_readwrite(plaintext_buf);
+	nbbio_enable_read(plaintext_buf, state->timeout);
+    } else {
+	if (NBBIO_ACTIVE_FLAGS(plaintext_buf))
+	    nbbio_slumber(plaintext_buf, state->timeout);
+    }
+}
+
+/* tlsp_plaintext_event - plaintext was read/written */
+
+static void tlsp_plaintext_event(int event, void *context)
+{
+    TLSP_STATE *state = (TLSP_STATE *) context;
+
+    /*
+     * Safety alert: the plaintext pseudothreads have "slumbered" for too
+     * long (see code above). This means that the ciphertext pseudothreads
+     * are stuck.
+     */
+    if ((NBBIO_ERROR_FLAGS(state->plaintext_buf) & NBBIO_FLAG_TIMEOUT) != 0
+	&& NBBIO_ACTIVE_FLAGS(state->plaintext_buf) == 0)
+	msg_warn("deadlock on ciphertext stream for %s", state->remote_endpt);
+
+    /*
+     * This is easy, because the NBBIO layer has already done the event
+     * decoding and plaintext I/O for us. All we need to do is decide if we
+     * want to read or write more plaintext.
+     */
+    tlsp_strategy(state);
+    /* At this point, state could be a dangling pointer. */
+}
+
+/* tlsp_ciphertext_event - ciphertext is ready to read/write */
+
+static void tlsp_ciphertext_event(int event, void *context)
+{
+    TLSP_STATE *state = (TLSP_STATE *) context;
+
+    /*
+     * Without a TLS equivalent of the NBBIO layer, we must decode the events
+     * ourselves and do the ciphertext I/O. Then, we can decide if we want to
+     * read or write more ciphertext.
+     */
+    if (event == EVENT_READ || event == EVENT_WRITE) {
+	tlsp_strategy(state);
+	/* At this point, state could be a dangling pointer. */
+    } else {
+	if (event == EVENT_TIME && state->ssl_last_err == SSL_ERROR_NONE)
+	    msg_warn("deadlock on plaintext stream for %s",
+		     state->remote_endpt);
+	else
+	    msg_warn("ciphertext read/write %s for %s",
+		     event == EVENT_TIME ? "timeout" : "error",
+		     state->remote_endpt);
+	tlsp_state_free(state);
+    }
+}
+
+/* tlsp_client_start_pre_handshake - turn on TLS or force disconnect */
+
+static int tlsp_client_start_pre_handshake(TLSP_STATE *state)
+{
+    state->client_start_props->ctx = state->appl_state;
+    state->client_start_props->fd = state->ciphertext_fd;
+    state->tls_context = tls_client_start(state->client_start_props);
+    if (state->tls_context != 0)
+	return (TLSP_STAT_OK);
+
+    tlsp_state_free(state);
+    return (TLSP_STAT_ERR);
+}
+
+/* tlsp_server_start_pre_handshake - turn on TLS or force disconnect */
+
+static int tlsp_server_start_pre_handshake(TLSP_STATE *state)
+{
+    TLS_SERVER_START_PROPS props;
+    static char *cipher_grade;
+    static VSTRING *cipher_exclusions;
+
+    /*
+     * The code in this routine is pasted literally from smtpd(8). I am not
+     * going to sanitize this because doing so surely will break things in
+     * unexpected ways.
+     */
+
+    /*
+     * Perform the before-handshake portion of per-session initialization.
+     * Pass a null VSTREAM to indicate that this program will do the
+     * ciphertext I/O, not libtls.
+     * 
+     * The cipher grade and exclusions don't change between sessions. Compute
+     * just once and cache.
+     */
+#define ADD_EXCLUDE(vstr, str) \
+    do { \
+	if (*(str)) \
+	    vstring_sprintf_append((vstr), "%s%s", \
+				   VSTRING_LEN(vstr) ? " " : "", (str)); \
+    } while (0)
+
+    if (cipher_grade == 0) {
+	cipher_grade =
+	    var_tlsp_enforce_tls ? var_tlsp_tls_mand_ciph : var_tlsp_tls_ciph;
+	cipher_exclusions = vstring_alloc(10);
+	ADD_EXCLUDE(cipher_exclusions, var_tlsp_tls_excl_ciph);
+	if (var_tlsp_enforce_tls)
+	    ADD_EXCLUDE(cipher_exclusions, var_tlsp_tls_mand_excl);
+	if (ask_client_cert)
+	    ADD_EXCLUDE(cipher_exclusions, "aNULL");
+    }
+    state->tls_context =
+	TLS_SERVER_START(&props,
+			 ctx = tlsp_server_ctx,
+			 stream = (VSTREAM *) 0,/* unused */
+			 fd = state->ciphertext_fd,
+			 timeout = 0,		/* unused */
+			 requirecert = (var_tlsp_tls_req_ccert
+					&& var_tlsp_enforce_tls),
+			 serverid = state->server_id,
+			 namaddr = state->remote_endpt,
+			 cipher_grade = cipher_grade,
+			 cipher_exclusions = STR(cipher_exclusions),
+			 mdalg = var_tlsp_tls_fpt_dgst);
+
+    if (state->tls_context == 0) {
+	tlsp_state_free(state);
+	return (TLSP_STAT_ERR);
+    }
+
+    /*
+     * XXX Do we care about TLS session rate limits? Good postscreen(8)
+     * clients will occasionally require the tlsproxy to renew their
+     * allowlist status, but bad clients hammering the server can suck up
+     * lots of CPU cycles. Per-client concurrency limits in postscreen(8)
+     * will divert only naive security "researchers".
+     */
+    return (TLSP_STAT_OK);
+}
+
+ /*
+  * From here on down is low-level code that sets up the plumbing before
+  * passing control to the TLS engine above.
+  */
+
+/* tlsp_request_read_event - pre-handshake event boiler plate */
+
+static void tlsp_request_read_event(int fd, EVENT_NOTIFY_FN handler,
+				            int timeout, void *context)
+{
+    event_enable_read(fd, handler, context);
+    event_request_timer(handler, context, timeout);
+}
+
+/* tlsp_accept_event - pre-handshake event boiler plate */
+
+static void tlsp_accept_event(int event, EVENT_NOTIFY_FN handler,
+			              void *context)
+{
+    if (event != EVENT_TIME)
+	event_cancel_timer(handler, context);
+    else
+	errno = ETIMEDOUT;
+    /* tlsp_state_free() disables pre-handshake plaintext I/O events. */
+}
+
+/* tlsp_get_fd_event - receive final connection hand-off information */
+
+static void tlsp_get_fd_event(int event, void *context)
+{
+    const char *myname = "tlsp_get_fd_event";
+    TLSP_STATE *state = (TLSP_STATE *) context;
+    int     plaintext_fd = vstream_fileno(state->plaintext_stream);
+    int     status;
+
+    /*
+     * At this point we still manually manage plaintext read/write/timeout
+     * events. Disable I/O events on the plaintext stream until the TLS
+     * handshake is completed. Every code path must either destroy state, or
+     * request the next event, otherwise we have a file and memory leak.
+     */
+    tlsp_accept_event(event, tlsp_get_fd_event, (void *) state);
+    event_disable_readwrite(plaintext_fd);
+
+    if (event != EVENT_READ
+	|| (state->ciphertext_fd = LOCAL_RECV_FD(plaintext_fd)) < 0) {
+	msg_warn("%s: receive remote SMTP peer file descriptor: %m", myname);
+	tlsp_state_free(state);
+	return;
+    }
+
+    /*
+     * This is a bit early, to ensure that timer events for this file handle
+     * are guaranteed to be turned off by the TLSP_STATE destructor.
+     */
+    state->ciphertext_timer = tlsp_ciphertext_event;
+    non_blocking(state->ciphertext_fd, NON_BLOCKING);
+
+    /*
+     * Perform the TLS layer before-handshake initialization. We perform the
+     * remainder after the actual TLS handshake completes.
+     */
+    if (state->is_server_role)
+	status = tlsp_server_start_pre_handshake(state);
+    else
+	status = tlsp_client_start_pre_handshake(state);
+    if (status != TLSP_STAT_OK)
+	/* At this point, state is a dangling pointer. */
+	return;
+
+    /*
+     * Trigger the initial proxy server I/Os.
+     */
+    tlsp_strategy(state);
+    /* At this point, state could be a dangling pointer. */
+}
+
+/* tlsp_config_diff - report server-client config differences */
+
+static void tlsp_log_config_diff(const char *server_cfg, const char *client_cfg)
+{
+    VSTRING *diff_summary = vstring_alloc(100);
+    char   *saved_server = mystrdup(server_cfg);
+    char   *saved_client = mystrdup(client_cfg);
+    char   *server_field;
+    char   *client_field;
+    char   *server_next;
+    char   *client_next;
+
+    /*
+     * Not using argv_split(), because it would treat multiple consecutive
+     * newline characters as one.
+     */
+    for (server_field = saved_server, client_field = saved_client;
+	 server_field && client_field;
+	 server_field = server_next, client_field = client_next) {
+	server_next = split_at(server_field, '\n');
+	client_next = split_at(client_field, '\n');
+	if (strcmp(server_field, client_field) != 0) {
+	    if (LEN(diff_summary) > 0)
+		vstring_sprintf_append(diff_summary, "; ");
+	    vstring_sprintf_append(diff_summary,
+				   "(server) '%s' != (client) '%s'",
+				   server_field, client_field);
+	}
+    }
+    msg_warn("%s", STR(diff_summary));
+
+    vstring_free(diff_summary);
+    myfree(saved_client);
+    myfree(saved_server);
+}
+
+/* tlsp_client_init - initialize a TLS client engine */
+
+static TLS_APPL_STATE *tlsp_client_init(TLS_CLIENT_PARAMS *tls_params,
+				          TLS_CLIENT_INIT_PROPS *init_props)
+{
+    TLS_APPL_STATE *appl_state;
+    VSTRING *param_buf;
+    char   *param_key;
+    VSTRING *init_buf;
+    char   *init_key;
+    int     log_hints = 0;
+
+    /*
+     * Use one TLS_APPL_STATE object for all requests that specify the same
+     * TLS_CLIENT_INIT_PROPS. Each TLS_APPL_STATE owns an SSL_CTX, which is
+     * expensive to create. Bug: TLS_CLIENT_PARAMS are not used when creating
+     * a TLS_APPL_STATE instance.
+     * 
+     * First, compute the TLS_APPL_STATE cache lookup key. Save a copy of the
+     * pre-jail request TLS_CLIENT_PARAMS and TLSPROXY_CLIENT_INIT_PROPS
+     * settings, so that we can detect post-jail requests that do not match.
+     */
+    param_buf = vstring_alloc(100);
+    param_key = tls_proxy_client_param_serialize(attr_print_plain, param_buf,
+						 tls_params);
+    init_buf = vstring_alloc(100);
+    init_key = tls_proxy_client_init_serialize(attr_print_plain, init_buf,
+					       init_props);
+    if (tlsp_pre_jail_done == 0) {
+	if (tlsp_pre_jail_client_param_key == 0
+	    || tlsp_pre_jail_client_init_key == 0) {
+	    tlsp_pre_jail_client_param_key = mystrdup(param_key);
+	    tlsp_pre_jail_client_init_key = mystrdup(init_key);
+	} else if (strcmp(tlsp_pre_jail_client_param_key, param_key) != 0
+		   || strcmp(tlsp_pre_jail_client_init_key, init_key) != 0) {
+	    msg_panic("tlsp_client_init: too many pre-jail calls");
+	}
+    }
+
+    /*
+     * Log a warning if a post-jail request uses unexpected TLS_CLIENT_PARAMS
+     * settings. Bug: TLS_CLIENT_PARAMS settings are not used when creating a
+     * TLS_APPL_STATE instance; this makes a mismatch of TLS_CLIENT_PARAMS
+     * settings problematic.
+     */
+    if (tlsp_pre_jail_done
+	&& !been_here_fixed(tlsp_params_mismatch_filter, param_key)
+	&& strcmp(tlsp_pre_jail_client_param_key, param_key) != 0) {
+	msg_warn("request from tlsproxy client with unexpected settings");
+	tlsp_log_config_diff(tlsp_pre_jail_client_param_key, param_key);
+	log_hints = 1;
+    }
+
+    /*
+     * Look up the cached TLS_APPL_STATE for this tls_client_init request.
+     */
+    if ((appl_state = (TLS_APPL_STATE *)
+	 htable_find(tlsp_client_app_cache, init_key)) == 0) {
+
+	/*
+	 * Before creating a TLS_APPL_STATE instance, log a warning if a
+	 * post-jail request differs from the saved pre-jail request AND the
+	 * post-jail request specifies file/directory pathname arguments.
+	 * Unexpected requests containing pathnames are problematic after
+	 * chroot (pathname resolution) and after dropping privileges (key
+	 * files must be root read-only). Unexpected requests are not a
+	 * problem as long as they contain no pathnames (for example a
+	 * tls_loglevel change).
+	 * 
+	 * We could eliminate some of this complication by adding code that
+	 * opens a cert/key lookup table at pre-jail time, and by reading
+	 * cert/key info on-the-fly from that table. But then all requests
+	 * would still have to specify the same table.
+	 */
+#define NOT_EMPTY(x) ((x) && *(x))
+
+	if (tlsp_pre_jail_done
+	    && strcmp(tlsp_pre_jail_client_init_key, init_key) != 0
+	    && (NOT_EMPTY(init_props->chain_files)
+		|| NOT_EMPTY(init_props->cert_file)
+		|| NOT_EMPTY(init_props->key_file)
+		|| NOT_EMPTY(init_props->dcert_file)
+		|| NOT_EMPTY(init_props->dkey_file)
+		|| NOT_EMPTY(init_props->eccert_file)
+		|| NOT_EMPTY(init_props->eckey_file)
+		|| NOT_EMPTY(init_props->CAfile)
+		|| NOT_EMPTY(init_props->CApath))) {
+	    msg_warn("request from tlsproxy client with unexpected settings");
+	    tlsp_log_config_diff(tlsp_pre_jail_client_init_key, init_key);
+	    log_hints = 1;
+	}
+    }
+    if (log_hints)
+	msg_warn("to avoid this warning, 1) identify the tlsproxy "
+		 "client that is making this request, 2) configure "
+		 "a custom tlsproxy service with settings that "
+		 "match that tlsproxy client, and 3) configure "
+		 "that tlsproxy client with a tlsproxy_service_name "
+		 "setting that resolves to that custom tlsproxy "
+		 "service");
+
+    /*
+     * TLS_APPL_STATE creation may fail when a post-jail request specifies
+     * unexpected cert/key information, but that is OK because we already
+     * logged a warning with configuration suggestions.
+     */
+    if (appl_state == 0
+	&& (appl_state = tls_client_init(init_props)) != 0) {
+	(void) htable_enter(tlsp_client_app_cache, init_key,
+			    (void *) appl_state);
+
+	/*
+	 * To maintain sanity, allow partial SSL_write() operations, and
+	 * allow SSL_write() buffer pointers to change after a WANT_READ or
+	 * WANT_WRITE result. This is based on OpenSSL developers talking on
+	 * a mailing list, but is not supported by documentation. If this
+	 * code stops working then no-one can be held responsible.
+	 */
+	SSL_CTX_set_mode(appl_state->ssl_ctx,
+			 SSL_MODE_ENABLE_PARTIAL_WRITE
+			 | SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER);
+    }
+    vstring_free(init_buf);
+    vstring_free(param_buf);
+    return (appl_state);
+}
+
+/* tlsp_close_event - pre-handshake plaintext-client close event */
+
+static void tlsp_close_event(int event, void *context)
+{
+    TLSP_STATE *state = (TLSP_STATE *) context;
+
+    tlsp_accept_event(event, tlsp_close_event, (void *) state);
+    tlsp_state_free(state);
+}
+
+/* tlsp_get_request_event - receive initial hand-off info */
+
+static void tlsp_get_request_event(int event, void *context)
+{
+    const char *myname = "tlsp_get_request_event";
+    TLSP_STATE *state = (TLSP_STATE *) context;
+    VSTREAM *plaintext_stream = state->plaintext_stream;
+    int     plaintext_fd = vstream_fileno(plaintext_stream);
+    static VSTRING *remote_endpt;
+    static VSTRING *server_id;
+    int     req_flags;
+    int     handshake_timeout;
+    int     session_timeout;
+    int     ready = 0;
+
+    /*
+     * At this point we still manually manage plaintext read/write/timeout
+     * events. Every code path must either destroy state or request the next
+     * event, otherwise this pseudo-thread is idle until the client goes
+     * away.
+     */
+    tlsp_accept_event(event, tlsp_get_request_event, (void *) state);
+
+    /*
+     * One-time initialization.
+     */
+    if (remote_endpt == 0) {
+	remote_endpt = vstring_alloc(10);
+	server_id = vstring_alloc(10);
+    }
+
+    /*
+     * Receive the initial request attributes. Receive the remainder after we
+     * figure out what role we are expected to play.
+     * 
+     * The tlsproxy server does not enforce per-request read/write deadlines or
+     * minimal data rates. Instead, the tlsproxy server relies on the
+     * tlsproxy client to enforce these context-dependent limits. When a
+     * tlsproxy client decides to time out, it will close its end of the
+     * tlsproxy stream, and the tlsproxy server will handle that immediately.
+     */
+    if (event != EVENT_READ
+	|| attr_scan(plaintext_stream, ATTR_FLAG_STRICT,
+		     RECV_ATTR_STR(TLS_ATTR_REMOTE_ENDPT, remote_endpt),
+		     RECV_ATTR_INT(TLS_ATTR_FLAGS, &req_flags),
+		     RECV_ATTR_INT(TLS_ATTR_TIMEOUT, &handshake_timeout),
+		     RECV_ATTR_INT(TLS_ATTR_TIMEOUT, &session_timeout),
+		     RECV_ATTR_STR(TLS_ATTR_SERVERID, server_id),
+		     ATTR_TYPE_END) != 5) {
+	msg_warn("%s: receive request attributes: %m", myname);
+	tlsp_state_free(state);
+	return;
+    }
+
+    /*
+     * XXX We use the same fixed timeout throughout the entire session for
+     * both plaintext and ciphertext communication. This timeout is just a
+     * safety feature; the real timeout will be enforced by our plaintext
+     * peer (except during TLS the handshake, when we intentionally disable
+     * plaintext I/O).
+     */
+    state->remote_endpt = mystrdup(STR(remote_endpt));
+    state->server_id = mystrdup(STR(server_id));
+    msg_info("CONNECT %s %s",
+	     (req_flags & TLS_PROXY_FLAG_ROLE_SERVER) ? "from" :
+	     (req_flags & TLS_PROXY_FLAG_ROLE_CLIENT) ? "to" :
+	     "(bogus_direction)", state->remote_endpt);
+    state->req_flags = req_flags;
+    /* state->is_server_role is set below. */
+    state->handshake_timeout = handshake_timeout;
+    state->session_timeout = session_timeout + 10;	/* XXX */
+
+    /*
+     * Receive the TLS preferences now, to reduce the number of protocol
+     * roundtrips.
+     */
+    switch (req_flags & (TLS_PROXY_FLAG_ROLE_CLIENT | TLS_PROXY_FLAG_ROLE_SERVER)) {
+    case TLS_PROXY_FLAG_ROLE_CLIENT:
+	state->is_server_role = 0;
+	if (attr_scan(plaintext_stream, ATTR_FLAG_STRICT,
+		      RECV_ATTR_FUNC(tls_proxy_client_param_scan,
+				     (void *) &state->tls_params),
+		      RECV_ATTR_FUNC(tls_proxy_client_init_scan,
+				     (void *) &state->client_init_props),
+		      RECV_ATTR_FUNC(tls_proxy_client_start_scan,
+				     (void *) &state->client_start_props),
+		      ATTR_TYPE_END) != 3) {
+	    msg_warn("%s: receive client TLS settings: %m", myname);
+	    tlsp_state_free(state);
+	    return;
+	}
+	state->appl_state = tlsp_client_init(state->tls_params,
+					     state->client_init_props);
+	ready = state->appl_state != 0;
+	break;
+    case TLS_PROXY_FLAG_ROLE_SERVER:
+	state->is_server_role = 1;
+	ready = (tlsp_server_ctx != 0);
+	break;
+    default:
+	state->is_server_role = 0;
+	msg_warn("%s: bad request flags: 0x%x", myname, req_flags);
+	ready = 0;
+    }
+
+    /*
+     * For portability we must send some data, after receiving the request
+     * attributes and before receiving the remote file descriptor.
+     * 
+     * If the requested TLS engine is unavailable, hang up after making sure
+     * that the plaintext peer has received our "sorry" indication.
+     */
+    if (attr_print(plaintext_stream, ATTR_FLAG_NONE,
+		   SEND_ATTR_INT(MAIL_ATTR_STATUS, ready),
+		   ATTR_TYPE_END) != 0
+	|| vstream_fflush(plaintext_stream) != 0
+	|| ready == 0) {
+	tlsp_request_read_event(plaintext_fd, tlsp_close_event,
+				TLSP_INIT_TIMEOUT, (void *) state);
+	return;
+    } else {
+	tlsp_request_read_event(plaintext_fd, tlsp_get_fd_event,
+				TLSP_INIT_TIMEOUT, (void *) state);
+	return;
+    }
+}
+
+/* tlsp_service - handle new client connection */
+
+static void tlsp_service(VSTREAM *plaintext_stream,
+			         char *service,
+			         char **argv)
+{
+    TLSP_STATE *state;
+    int     plaintext_fd = vstream_fileno(plaintext_stream);
+
+    /*
+     * Sanity check. This service takes no command-line arguments.
+     */
+    if (argv[0])
+	msg_fatal("unexpected command-line argument: %s", argv[0]);
+
+    /*
+     * This program handles multiple connections, so it must not block. We
+     * use event-driven code for all operations that introduce latency.
+     * Except that attribute lists are sent/received synchronously, once the
+     * socket is found to be ready for transmission.
+     */
+    non_blocking(plaintext_fd, NON_BLOCKING);
+    vstream_control(plaintext_stream,
+		    CA_VSTREAM_CTL_PATH("plaintext"),
+		    CA_VSTREAM_CTL_TIMEOUT(5),
+		    CA_VSTREAM_CTL_END);
+
+    (void) attr_print(plaintext_stream, ATTR_FLAG_NONE,
+		   SEND_ATTR_STR(MAIL_ATTR_PROTO, MAIL_ATTR_PROTO_TLSPROXY),
+		      ATTR_TYPE_END);
+    if (vstream_fflush(plaintext_stream) != 0)
+	msg_warn("write %s attribute: %m", MAIL_ATTR_PROTO);
+
+    /*
+     * Receive postscreen's remote SMTP client address/port and socket.
+     */
+    state = tlsp_state_create(service, plaintext_stream);
+    tlsp_request_read_event(plaintext_fd, tlsp_get_request_event,
+			    TLSP_INIT_TIMEOUT, (void *) state);
+}
+
+/* pre_jail_init_server - pre-jail initialization */
+
+static void pre_jail_init_server(void)
+{
+    TLS_SERVER_INIT_PROPS props;
+    const char *cert_file;
+    int     have_server_cert;
+    int     no_server_cert_ok;
+    int     require_server_cert;
+
+    /*
+     * The code in this routine is pasted literally from smtpd(8). I am not
+     * going to sanitize this because doing so surely will break things in
+     * unexpected ways.
+     */
+    if (*var_tlsp_tls_level) {
+	switch (tls_level_lookup(var_tlsp_tls_level)) {
+	default:
+	    msg_fatal("Invalid TLS level \"%s\"", var_tlsp_tls_level);
+	    /* NOTREACHED */
+	    break;
+	case TLS_LEV_SECURE:
+	case TLS_LEV_VERIFY:
+	case TLS_LEV_FPRINT:
+	    msg_warn("%s: unsupported TLS level \"%s\", using \"encrypt\"",
+		     VAR_TLSP_TLS_LEVEL, var_tlsp_tls_level);
+	    /* FALLTHROUGH */
+	case TLS_LEV_ENCRYPT:
+	    var_tlsp_enforce_tls = var_tlsp_use_tls = 1;
+	    break;
+	case TLS_LEV_MAY:
+	    var_tlsp_enforce_tls = 0;
+	    var_tlsp_use_tls = 1;
+	    break;
+	case TLS_LEV_NONE:
+	    var_tlsp_enforce_tls = var_tlsp_use_tls = 0;
+	    break;
+	}
+    }
+    var_tlsp_use_tls = var_tlsp_use_tls || var_tlsp_enforce_tls;
+    if (!var_tlsp_use_tls) {
+	msg_warn("TLS server role is disabled with %s or %s",
+		 VAR_TLSP_TLS_LEVEL, VAR_TLSP_USE_TLS);
+	return;
+    }
+
+    /*
+     * Load TLS keys before dropping privileges.
+     * 
+     * Can't use anonymous ciphers if we want client certificates. Must use
+     * anonymous ciphers if we have no certificates.
+     */
+    ask_client_cert = require_server_cert =
+	(var_tlsp_tls_ask_ccert
+	 || (var_tlsp_enforce_tls && var_tlsp_tls_req_ccert));
+    if (strcasecmp(var_tlsp_tls_cert_file, "none") == 0) {
+	no_server_cert_ok = 1;
+	cert_file = "";
+    } else {
+	no_server_cert_ok = 0;
+	cert_file = var_tlsp_tls_cert_file;
+    }
+    have_server_cert =
+	(*cert_file || *var_tlsp_tls_dcert_file || *var_tlsp_tls_eccert_file);
+
+    if (*var_tlsp_tls_chain_files != 0) {
+	if (!have_server_cert)
+	    have_server_cert = 1;
+	else
+	    msg_warn("Both %s and one or more of the legacy "
+		     " %s, %s or %s are non-empty; the legacy "
+		     " parameters will be ignored",
+		     VAR_TLSP_TLS_CHAIN_FILES,
+		     VAR_TLSP_TLS_CERT_FILE,
+		     VAR_TLSP_TLS_ECCERT_FILE,
+		     VAR_TLSP_TLS_DCERT_FILE);
+    }
+    /* Some TLS configuration errors are not show stoppers. */
+    if (!have_server_cert && require_server_cert)
+	msg_warn("Need a server cert to request client certs");
+    if (!var_tlsp_enforce_tls && var_tlsp_tls_req_ccert)
+	msg_warn("Can't require client certs unless TLS is required");
+    /* After a show-stopper error, log a warning. */
+    if (have_server_cert || (no_server_cert_ok && !require_server_cert)) {
+
+	tls_pre_jail_init(TLS_ROLE_SERVER);
+
+	/*
+	 * Large parameter lists are error-prone, so we emulate a language
+	 * feature that C does not have natively: named parameter lists.
+	 */
+	tlsp_server_ctx =
+	    TLS_SERVER_INIT(&props,
+			    log_param = VAR_TLSP_TLS_LOGLEVEL,
+			    log_level = var_tlsp_tls_loglevel,
+			    verifydepth = var_tlsp_tls_ccert_vd,
+			    cache_type = TLS_MGR_SCACHE_SMTPD,
+			    set_sessid = var_tlsp_tls_set_sessid,
+			    chain_files = var_tlsp_tls_chain_files,
+			    cert_file = cert_file,
+			    key_file = var_tlsp_tls_key_file,
+			    dcert_file = var_tlsp_tls_dcert_file,
+			    dkey_file = var_tlsp_tls_dkey_file,
+			    eccert_file = var_tlsp_tls_eccert_file,
+			    eckey_file = var_tlsp_tls_eckey_file,
+			    CAfile = var_tlsp_tls_CAfile,
+			    CApath = var_tlsp_tls_CApath,
+			    dh1024_param_file
+			    = var_tlsp_tls_dh1024_param_file,
+			    dh512_param_file
+			    = var_tlsp_tls_dh512_param_file,
+			    eecdh_grade = var_tlsp_tls_eecdh,
+			    protocols = var_tlsp_enforce_tls ?
+			    var_tlsp_tls_mand_proto :
+			    var_tlsp_tls_proto,
+			    ask_ccert = ask_client_cert,
+			    mdalg = var_tlsp_tls_fpt_dgst);
+    } else {
+	msg_warn("No server certs available. TLS can't be enabled");
+    }
+
+    /*
+     * To maintain sanity, allow partial SSL_write() operations, and allow
+     * SSL_write() buffer pointers to change after a WANT_READ or WANT_WRITE
+     * result. This is based on OpenSSL developers talking on a mailing list,
+     * but is not supported by documentation. If this code stops working then
+     * no-one can be held responsible.
+     */
+    if (tlsp_server_ctx)
+	SSL_CTX_set_mode(tlsp_server_ctx->ssl_ctx,
+			 SSL_MODE_ENABLE_PARTIAL_WRITE
+			 | SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER);
+}
+
+/* pre_jail_init_client - pre-jail initialization */
+
+static void pre_jail_init_client(void)
+{
+    int     clnt_use_tls;
+
+    /*
+     * The cache with TLS_APPL_STATE instances for different TLS_CLIENT_INIT
+     * configurations.
+     */
+    tlsp_client_app_cache = htable_create(10);
+
+    /*
+     * Most sites don't use TLS client certs/keys. In that case, enabling
+     * tlsproxy-based connection caching is trivial.
+     * 
+     * But some sites do use TLS client certs/keys, and that is challenging when
+     * tlsproxy runs in a post-jail environment: chroot breaks pathname
+     * resolution, and an unprivileged process should not be able to open
+     * files with secrets. The workaround: assume that most of those sites
+     * will use a fixed TLS client identity. In that case, tlsproxy can load
+     * the corresponding certs/keys at pre-jail time, so that secrets can
+     * remain read-only for root. As long as the tlsproxy pre-jail TLS client
+     * configuration with cert or key pathnames is the same as the one used
+     * in the Postfix SMTP client, sites can selectively or globally enable
+     * tlsproxy-based connection caching without additional TLS
+     * configuration.
+     * 
+     * Loading one TLS client configuration at pre-jail time is not sufficient
+     * for the minority of sites that want to use TLS connection caching with
+     * multiple TLS client identities. To alert the operator, tlsproxy will
+     * log a warning when a TLS_CLIENT_INIT message specifies a different
+     * configuration than the tlsproxy pre-jail client configuration, and
+     * that different configuration specifies file/directory pathname
+     * arguments. The workaround is to have one tlsproxy process per TLS
+     * client identity.
+     * 
+     * The general solution for single-identity or multi-identity clients is to
+     * stop loading certs and keys from individual files. Instead, have a
+     * cert/key map, indexed by client identity, read-only by root. After
+     * opening the map as root at pre-jail time, tlsproxy can read certs/keys
+     * on-the-fly as an unprivileged process at post-jail time. This is the
+     * approach that was already proposed for server-side SNI support, and it
+     * could be reused here. It would also end the proliferation of RSA
+     * cert/key parameters, DSA cert/key parameters, EC cert/key parameters,
+     * and so on.
+     * 
+     * Horror: In order to create the same pre-jail TLS client context as the
+     * one used in the Postfix SMTP client, we have to duplicate intricate
+     * SMTP client code, including a handful configuration parameters that
+     * tlsproxy does not need. We must duplicate the logic, so that we only
+     * load certs and keys when the SMTP client would load them.
+     */
+    if (*var_tlsp_clnt_level != 0)
+	switch (tls_level_lookup(var_tlsp_clnt_level)) {
+	case TLS_LEV_SECURE:
+	case TLS_LEV_VERIFY:
+	case TLS_LEV_DANE_ONLY:
+	case TLS_LEV_FPRINT:
+	case TLS_LEV_ENCRYPT:
+	    var_tlsp_clnt_use_tls = var_tlsp_clnt_enforce_tls = 1;
+	    break;
+	case TLS_LEV_DANE:
+	case TLS_LEV_MAY:
+	    var_tlsp_clnt_use_tls = 1;
+	    var_tlsp_clnt_enforce_tls = 0;
+	    break;
+	case TLS_LEV_NONE:
+	    var_tlsp_clnt_use_tls = var_tlsp_clnt_enforce_tls = 0;
+	    break;
+	default:
+	    /* tls_level_lookup() logs no warning. */
+	    /* session_tls_init() assumes that var_tlsp_clnt_level is sane. */
+	    msg_fatal("Invalid TLS level \"%s\"", var_tlsp_clnt_level);
+	}
+    clnt_use_tls = (var_tlsp_clnt_use_tls || var_tlsp_clnt_enforce_tls);
+
+    /*
+     * Initialize the TLS data before entering the chroot jail.
+     */
+    if (clnt_use_tls || var_tlsp_clnt_per_site[0] || var_tlsp_clnt_policy[0]) {
+	TLS_CLIENT_PARAMS tls_params;
+	TLS_CLIENT_INIT_PROPS init_props;
+
+	tls_pre_jail_init(TLS_ROLE_CLIENT);
+
+	/*
+	 * We get stronger type safety and a cleaner interface by combining
+	 * the various parameters into a single tls_client_props structure.
+	 * 
+	 * Large parameter lists are error-prone, so we emulate a language
+	 * feature that C does not have natively: named parameter lists.
+	 */
+	(void) tls_proxy_client_param_from_config(&tls_params);
+	(void) TLS_CLIENT_INIT_ARGS(&init_props,
+				    log_param = var_tlsp_clnt_logparam,
+				    log_level = var_tlsp_clnt_loglevel,
+				    verifydepth = var_tlsp_clnt_scert_vd,
+				    cache_type = TLS_MGR_SCACHE_SMTP,
+				    chain_files = var_tlsp_clnt_chain_files,
+				    cert_file = var_tlsp_clnt_cert_file,
+				    key_file = var_tlsp_clnt_key_file,
+				    dcert_file = var_tlsp_clnt_dcert_file,
+				    dkey_file = var_tlsp_clnt_dkey_file,
+				    eccert_file = var_tlsp_clnt_eccert_file,
+				    eckey_file = var_tlsp_clnt_eckey_file,
+				    CAfile = var_tlsp_clnt_CAfile,
+				    CApath = var_tlsp_clnt_CApath,
+				    mdalg = var_tlsp_clnt_fpt_dgst);
+	if (tlsp_client_init(&tls_params, &init_props) == 0)
+	    msg_warn("TLS client initialization failed");
+    }
+}
+
+/* pre_jail_init - pre-jail initialization */
+
+static void pre_jail_init(char *unused_name, char **unused_argv)
+{
+
+    /*
+     * Initialize roles separately.
+     */
+    pre_jail_init_server();
+    pre_jail_init_client();
+
+    /*
+     * tlsp_client_init() needs to know if it is called pre-jail or
+     * post-jail.
+     */
+    tlsp_pre_jail_done = 1;
+
+    /*
+     * Bug: TLS_CLIENT_PARAMS attributes are not used when creating a
+     * TLS_APPL_STATE instance; we can only warn about attribute mismatches.
+     */
+    tlsp_params_mismatch_filter = been_here_init(BH_BOUND_NONE, BH_FLAG_NONE);
+}
+
+MAIL_VERSION_STAMP_DECLARE;
+
+/* main - the main program */
+
+int     main(int argc, char **argv)
+{
+
+    /*
+     * Each table below initializes the named variables to their implicit
+     * default value, or to the explicit value in main.cf or master.cf. Here,
+     * "compat" means that a table initializes a variable "smtpd_blah" or
+     * "smtp_blah" that provides the implicit default value for variable
+     * "tlsproxy_blah" which is initialized by a different table. To make
+     * this work, the variables in a "compat" table must be initialized
+     * before the variables in the corresponding non-compat table.
+     */
+    static const CONFIG_INT_TABLE compat_int_table[] = {
+	VAR_SMTPD_TLS_CCERT_VD, DEF_SMTPD_TLS_CCERT_VD, &var_smtpd_tls_ccert_vd, 0, 0,
+	VAR_SMTP_TLS_SCERT_VD, DEF_SMTP_TLS_SCERT_VD, &var_smtp_tls_scert_vd, 0, 0,
+	0,
+    };
+    static const CONFIG_NINT_TABLE nint_table[] = {
+	VAR_TLSP_TLS_CCERT_VD, DEF_TLSP_TLS_CCERT_VD, &var_tlsp_tls_ccert_vd, 0, 0,
+	VAR_TLSP_CLNT_SCERT_VD, DEF_TLSP_CLNT_SCERT_VD, &var_tlsp_clnt_scert_vd, 0, 0,
+	0,
+    };
+    static const CONFIG_TIME_TABLE time_table[] = {
+	VAR_TLSP_WATCHDOG, DEF_TLSP_WATCHDOG, &var_tlsp_watchdog, 10, 0,
+	0,
+    };
+    static const CONFIG_BOOL_TABLE compat_bool_table[] = {
+	VAR_SMTPD_USE_TLS, DEF_SMTPD_USE_TLS, &var_smtpd_use_tls,
+	VAR_SMTPD_ENFORCE_TLS, DEF_SMTPD_ENFORCE_TLS, &var_smtpd_enforce_tls,
+	VAR_SMTPD_TLS_ACERT, DEF_SMTPD_TLS_ACERT, &var_smtpd_tls_ask_ccert,
+	VAR_SMTPD_TLS_RCERT, DEF_SMTPD_TLS_RCERT, &var_smtpd_tls_req_ccert,
+	VAR_SMTPD_TLS_SET_SESSID, DEF_SMTPD_TLS_SET_SESSID, &var_smtpd_tls_set_sessid,
+	VAR_SMTP_USE_TLS, DEF_SMTP_USE_TLS, &var_smtp_use_tls,
+	VAR_SMTP_ENFORCE_TLS, DEF_SMTP_ENFORCE_TLS, &var_smtp_enforce_tls,
+	0,
+    };
+    static const CONFIG_NBOOL_TABLE nbool_table[] = {
+	VAR_TLSP_USE_TLS, DEF_TLSP_USE_TLS, &var_tlsp_use_tls,
+	VAR_TLSP_ENFORCE_TLS, DEF_TLSP_ENFORCE_TLS, &var_tlsp_enforce_tls,
+	VAR_TLSP_TLS_ACERT, DEF_TLSP_TLS_ACERT, &var_tlsp_tls_ask_ccert,
+	VAR_TLSP_TLS_RCERT, DEF_TLSP_TLS_RCERT, &var_tlsp_tls_req_ccert,
+	VAR_TLSP_TLS_SET_SESSID, DEF_TLSP_TLS_SET_SESSID, &var_tlsp_tls_set_sessid,
+	VAR_TLSP_CLNT_USE_TLS, DEF_TLSP_CLNT_USE_TLS, &var_tlsp_clnt_use_tls,
+	VAR_TLSP_CLNT_ENFORCE_TLS, DEF_TLSP_CLNT_ENFORCE_TLS, &var_tlsp_clnt_enforce_tls,
+	0,
+    };
+    static const CONFIG_STR_TABLE compat_str_table[] = {
+	VAR_SMTPD_TLS_CHAIN_FILES, DEF_SMTPD_TLS_CHAIN_FILES, &var_smtpd_tls_chain_files, 0, 0,
+	VAR_SMTPD_TLS_CERT_FILE, DEF_SMTPD_TLS_CERT_FILE, &var_smtpd_tls_cert_file, 0, 0,
+	VAR_SMTPD_TLS_KEY_FILE, DEF_SMTPD_TLS_KEY_FILE, &var_smtpd_tls_key_file, 0, 0,
+	VAR_SMTPD_TLS_DCERT_FILE, DEF_SMTPD_TLS_DCERT_FILE, &var_smtpd_tls_dcert_file, 0, 0,
+	VAR_SMTPD_TLS_DKEY_FILE, DEF_SMTPD_TLS_DKEY_FILE, &var_smtpd_tls_dkey_file, 0, 0,
+	VAR_SMTPD_TLS_ECCERT_FILE, DEF_SMTPD_TLS_ECCERT_FILE, &var_smtpd_tls_eccert_file, 0, 0,
+	VAR_SMTPD_TLS_ECKEY_FILE, DEF_SMTPD_TLS_ECKEY_FILE, &var_smtpd_tls_eckey_file, 0, 0,
+	VAR_SMTPD_TLS_CA_FILE, DEF_SMTPD_TLS_CA_FILE, &var_smtpd_tls_CAfile, 0, 0,
+	VAR_SMTPD_TLS_CA_PATH, DEF_SMTPD_TLS_CA_PATH, &var_smtpd_tls_CApath, 0, 0,
+	VAR_SMTPD_TLS_CIPH, DEF_SMTPD_TLS_CIPH, &var_smtpd_tls_ciph, 1, 0,
+	VAR_SMTPD_TLS_MAND_CIPH, DEF_SMTPD_TLS_MAND_CIPH, &var_smtpd_tls_mand_ciph, 1, 0,
+	VAR_SMTPD_TLS_EXCL_CIPH, DEF_SMTPD_TLS_EXCL_CIPH, &var_smtpd_tls_excl_ciph, 0, 0,
+	VAR_SMTPD_TLS_MAND_EXCL, DEF_SMTPD_TLS_MAND_EXCL, &var_smtpd_tls_mand_excl, 0, 0,
+	VAR_SMTPD_TLS_PROTO, DEF_SMTPD_TLS_PROTO, &var_smtpd_tls_proto, 0, 0,
+	VAR_SMTPD_TLS_MAND_PROTO, DEF_SMTPD_TLS_MAND_PROTO, &var_smtpd_tls_mand_proto, 0, 0,
+	VAR_SMTPD_TLS_512_FILE, DEF_SMTPD_TLS_512_FILE, &var_smtpd_tls_dh512_param_file, 0, 0,
+	VAR_SMTPD_TLS_1024_FILE, DEF_SMTPD_TLS_1024_FILE, &var_smtpd_tls_dh1024_param_file, 0, 0,
+	VAR_SMTPD_TLS_EECDH, DEF_SMTPD_TLS_EECDH, &var_smtpd_tls_eecdh, 1, 0,
+	VAR_SMTPD_TLS_FPT_DGST, DEF_SMTPD_TLS_FPT_DGST, &var_smtpd_tls_fpt_dgst, 1, 0,
+	VAR_SMTPD_TLS_LOGLEVEL, DEF_SMTPD_TLS_LOGLEVEL, &var_smtpd_tls_loglevel, 0, 0,
+	VAR_SMTPD_TLS_LEVEL, DEF_SMTPD_TLS_LEVEL, &var_smtpd_tls_level, 0, 0,
+	VAR_SMTP_TLS_CHAIN_FILES, DEF_SMTP_TLS_CHAIN_FILES, &var_smtp_tls_chain_files, 0, 0,
+	VAR_SMTP_TLS_CERT_FILE, DEF_SMTP_TLS_CERT_FILE, &var_smtp_tls_cert_file, 0, 0,
+	VAR_SMTP_TLS_KEY_FILE, DEF_SMTP_TLS_KEY_FILE, &var_smtp_tls_key_file, 0, 0,
+	VAR_SMTP_TLS_DCERT_FILE, DEF_SMTP_TLS_DCERT_FILE, &var_smtp_tls_dcert_file, 0, 0,
+	VAR_SMTP_TLS_DKEY_FILE, DEF_SMTP_TLS_DKEY_FILE, &var_smtp_tls_dkey_file, 0, 0,
+	VAR_SMTP_TLS_CA_FILE, DEF_SMTP_TLS_CA_FILE, &var_smtp_tls_CAfile, 0, 0,
+	VAR_SMTP_TLS_CA_PATH, DEF_SMTP_TLS_CA_PATH, &var_smtp_tls_CApath, 0, 0,
+	VAR_SMTP_TLS_FPT_DGST, DEF_SMTP_TLS_FPT_DGST, &var_smtp_tls_fpt_dgst, 1, 0,
+	VAR_SMTP_TLS_ECCERT_FILE, DEF_SMTP_TLS_ECCERT_FILE, &var_smtp_tls_eccert_file, 0, 0,
+	VAR_SMTP_TLS_ECKEY_FILE, DEF_SMTP_TLS_ECKEY_FILE, &var_smtp_tls_eckey_file, 0, 0,
+	VAR_SMTP_TLS_LOGLEVEL, DEF_SMTP_TLS_LOGLEVEL, &var_smtp_tls_loglevel, 0, 0,
+	VAR_SMTP_TLS_PER_SITE, DEF_SMTP_TLS_PER_SITE, &var_smtp_tls_per_site, 0, 0,
+	VAR_SMTP_TLS_LEVEL, DEF_SMTP_TLS_LEVEL, &var_smtp_tls_level, 0, 0,
+	VAR_SMTP_TLS_POLICY, DEF_SMTP_TLS_POLICY, &var_smtp_tls_policy, 0, 0,
+	0,
+    };
+    static const CONFIG_STR_TABLE str_table[] = {
+	VAR_TLSP_TLS_CHAIN_FILES, DEF_TLSP_TLS_CHAIN_FILES, &var_tlsp_tls_chain_files, 0, 0,
+	VAR_TLSP_TLS_CERT_FILE, DEF_TLSP_TLS_CERT_FILE, &var_tlsp_tls_cert_file, 0, 0,
+	VAR_TLSP_TLS_KEY_FILE, DEF_TLSP_TLS_KEY_FILE, &var_tlsp_tls_key_file, 0, 0,
+	VAR_TLSP_TLS_DCERT_FILE, DEF_TLSP_TLS_DCERT_FILE, &var_tlsp_tls_dcert_file, 0, 0,
+	VAR_TLSP_TLS_DKEY_FILE, DEF_TLSP_TLS_DKEY_FILE, &var_tlsp_tls_dkey_file, 0, 0,
+	VAR_TLSP_TLS_ECCERT_FILE, DEF_TLSP_TLS_ECCERT_FILE, &var_tlsp_tls_eccert_file, 0, 0,
+	VAR_TLSP_TLS_ECKEY_FILE, DEF_TLSP_TLS_ECKEY_FILE, &var_tlsp_tls_eckey_file, 0, 0,
+	VAR_TLSP_TLS_CA_FILE, DEF_TLSP_TLS_CA_FILE, &var_tlsp_tls_CAfile, 0, 0,
+	VAR_TLSP_TLS_CA_PATH, DEF_TLSP_TLS_CA_PATH, &var_tlsp_tls_CApath, 0, 0,
+	VAR_TLSP_TLS_CIPH, DEF_TLSP_TLS_CIPH, &var_tlsp_tls_ciph, 1, 0,
+	VAR_TLSP_TLS_MAND_CIPH, DEF_TLSP_TLS_MAND_CIPH, &var_tlsp_tls_mand_ciph, 1, 0,
+	VAR_TLSP_TLS_EXCL_CIPH, DEF_TLSP_TLS_EXCL_CIPH, &var_tlsp_tls_excl_ciph, 0, 0,
+	VAR_TLSP_TLS_MAND_EXCL, DEF_TLSP_TLS_MAND_EXCL, &var_tlsp_tls_mand_excl, 0, 0,
+	VAR_TLSP_TLS_PROTO, DEF_TLSP_TLS_PROTO, &var_tlsp_tls_proto, 0, 0,
+	VAR_TLSP_TLS_MAND_PROTO, DEF_TLSP_TLS_MAND_PROTO, &var_tlsp_tls_mand_proto, 0, 0,
+	VAR_TLSP_TLS_512_FILE, DEF_TLSP_TLS_512_FILE, &var_tlsp_tls_dh512_param_file, 0, 0,
+	VAR_TLSP_TLS_1024_FILE, DEF_TLSP_TLS_1024_FILE, &var_tlsp_tls_dh1024_param_file, 0, 0,
+	VAR_TLSP_TLS_EECDH, DEF_TLSP_TLS_EECDH, &var_tlsp_tls_eecdh, 1, 0,
+	VAR_TLSP_TLS_FPT_DGST, DEF_TLSP_TLS_FPT_DGST, &var_tlsp_tls_fpt_dgst, 1, 0,
+	VAR_TLSP_TLS_LOGLEVEL, DEF_TLSP_TLS_LOGLEVEL, &var_tlsp_tls_loglevel, 0, 0,
+	VAR_TLSP_TLS_LEVEL, DEF_TLSP_TLS_LEVEL, &var_tlsp_tls_level, 0, 0,
+	VAR_TLSP_CLNT_LOGLEVEL, DEF_TLSP_CLNT_LOGLEVEL, &var_tlsp_clnt_loglevel, 0, 0,
+	VAR_TLSP_CLNT_LOGPARAM, DEF_TLSP_CLNT_LOGPARAM, &var_tlsp_clnt_logparam, 0, 0,
+	VAR_TLSP_CLNT_CHAIN_FILES, DEF_TLSP_CLNT_CHAIN_FILES, &var_tlsp_clnt_chain_files, 0, 0,
+	VAR_TLSP_CLNT_CERT_FILE, DEF_TLSP_CLNT_CERT_FILE, &var_tlsp_clnt_cert_file, 0, 0,
+	VAR_TLSP_CLNT_KEY_FILE, DEF_TLSP_CLNT_KEY_FILE, &var_tlsp_clnt_key_file, 0, 0,
+	VAR_TLSP_CLNT_DCERT_FILE, DEF_TLSP_CLNT_DCERT_FILE, &var_tlsp_clnt_dcert_file, 0, 0,
+	VAR_TLSP_CLNT_DKEY_FILE, DEF_TLSP_CLNT_DKEY_FILE, &var_tlsp_clnt_dkey_file, 0, 0,
+	VAR_TLSP_CLNT_ECCERT_FILE, DEF_TLSP_CLNT_ECCERT_FILE, &var_tlsp_clnt_eccert_file, 0, 0,
+	VAR_TLSP_CLNT_ECKEY_FILE, DEF_TLSP_CLNT_ECKEY_FILE, &var_tlsp_clnt_eckey_file, 0, 0,
+	VAR_TLSP_CLNT_CAFILE, DEF_TLSP_CLNT_CAFILE, &var_tlsp_clnt_CAfile, 0, 0,
+	VAR_TLSP_CLNT_CAPATH, DEF_TLSP_CLNT_CAPATH, &var_tlsp_clnt_CApath, 0, 0,
+	VAR_TLSP_CLNT_FPT_DGST, DEF_TLSP_CLNT_FPT_DGST, &var_tlsp_clnt_fpt_dgst, 1, 0,
+	VAR_TLSP_CLNT_LEVEL, DEF_TLSP_CLNT_LEVEL, &var_tlsp_clnt_level, 0, 0,
+	VAR_TLSP_CLNT_PER_SITE, DEF_TLSP_CLNT_PER_SITE, &var_tlsp_clnt_per_site, 0, 0,
+	VAR_TLSP_CLNT_POLICY, DEF_TLSP_CLNT_POLICY, &var_tlsp_clnt_policy, 0, 0,
+	0,
+    };
+
+    /*
+     * Fingerprint executables and core dumps.
+     */
+    MAIL_VERSION_STAMP_ALLOCATE;
+
+    /*
+     * Pass control to the event-driven service skeleton.
+     */
+    event_server_main(argc, argv, tlsp_service,
+		      CA_MAIL_SERVER_INT_TABLE(compat_int_table),
+		      CA_MAIL_SERVER_NINT_TABLE(nint_table),
+		      CA_MAIL_SERVER_STR_TABLE(compat_str_table),
+		      CA_MAIL_SERVER_STR_TABLE(str_table),
+		      CA_MAIL_SERVER_BOOL_TABLE(compat_bool_table),
+		      CA_MAIL_SERVER_NBOOL_TABLE(nbool_table),
+		      CA_MAIL_SERVER_TIME_TABLE(time_table),
+		      CA_MAIL_SERVER_PRE_INIT(pre_jail_init),
+		      CA_MAIL_SERVER_SLOW_EXIT(tlsp_drain),
+		      CA_MAIL_SERVER_RETIRE_ME,
+		      CA_MAIL_SERVER_WATCHDOG(&var_tlsp_watchdog),
+		      CA_MAIL_SERVER_UNLIMITED,
+		      0);
+}
+
+#else
+
+/* tlsp_service - respond to external trigger(s), non-TLS version */
+
+static void tlsp_service(VSTREAM *stream, char *unused_service,
+			         char **unused_argv)
+{
+    msg_info("TLS support is not compiled in -- exiting");
+    event_server_disconnect(stream);
+}
+
+/* main - the main program */
+
+int     main(int argc, char **argv)
+{
+
+    /*
+     * We can't simply use msg_fatal() here, because the logging hasn't been
+     * initialized. The text would disappear because stderr is redirected to
+     * /dev/null.
+     * 
+     * We invoke event_server_main() to complete program initialization
+     * (including logging) and then invoke the tlsp_service() routine to log
+     * the message that says why this program will not run.
+     */
+    event_server_main(argc, argv, tlsp_service,
+		      0);
+}
+
+#endif
diff --git a/src/tlsproxy/tlsproxy.h b/src/tlsproxy/tlsproxy.h
new file mode 100644
index 0000000..eacbb1f
--- /dev/null
+++ b/src/tlsproxy/tlsproxy.h
@@ -0,0 +1,69 @@
+/*++
+/* NAME
+/*	tlsproxy 3h
+/* SUMMARY
+/*	tlsproxy internal interfaces
+/* SYNOPSIS
+/*	#include <tlsproxy.h>
+/* DESCRIPTION
+/* .nf
+
+ /*
+  * Utility library.
+  */
+#include <vstream.h>
+#include <nbbio.h>
+
+ /*
+  * TLS library.
+  */
+#include <tls.h>
+
+ /*
+  * Internal interface.
+  */
+typedef struct {
+    int     flags;			/* see below */
+    int     req_flags;			/* request flags, see tls_proxy.h */
+    int     is_server_role;		/* avoid clumsy handler code */
+    char   *service;			/* argv[0] */
+    VSTREAM *plaintext_stream;		/* local peer: postscreen(8), etc. */
+    NBBIO  *plaintext_buf;		/* plaintext buffer */
+    int     ciphertext_fd;		/* remote peer */
+    EVENT_NOTIFY_FN ciphertext_timer;	/* kludge */
+    int     timeout;			/* read/write time limit */
+    int     handshake_timeout;		/* in-handshake time limit */
+    int     session_timeout;		/* post-handshake time limit */
+    char   *remote_endpt;		/* printable remote endpoint */
+    char   *server_id;			/* cache management */
+    TLS_APPL_STATE *appl_state;		/* libtls state */
+    TLS_SESS_STATE *tls_context;	/* libtls state */
+    int     ssl_last_err;		/* TLS I/O state */
+    TLS_CLIENT_PARAMS *tls_params;	/* globals not part of init_props */
+    TLS_SERVER_INIT_PROPS *server_init_props;
+    TLS_SERVER_START_PROPS *server_start_props;
+    TLS_CLIENT_INIT_PROPS *client_init_props;
+    TLS_CLIENT_START_PROPS *client_start_props;
+} TLSP_STATE;
+
+#define TLSP_FLAG_DO_HANDSHAKE	(1<<0)
+#define TLSP_FLAG_NO_MORE_CIPHERTEXT_IO (1<<1)	/* overrides DO_HANDSHAKE */
+
+extern TLSP_STATE *tlsp_state_create(const char *, VSTREAM *);
+extern void tlsp_state_free(TLSP_STATE *);
+
+/* LICENSE
+/* .ad
+/* .fi
+/*	The Secure Mailer license must be distributed with this software.
+/* AUTHOR(S)
+/*	Wietse Venema
+/*	IBM T.J. Watson Research
+/*	P.O. Box 704
+/*	Yorktown Heights, NY 10598, USA
+/*
+/*	Wietse Venema
+/*	Google, Inc.
+/*	111 8th Avenue
+/*	New York, NY 10011, USA
+/*--*/
diff --git a/src/tlsproxy/tlsproxy_state.c b/src/tlsproxy/tlsproxy_state.c
new file mode 100644
index 0000000..df6cbda
--- /dev/null
+++ b/src/tlsproxy/tlsproxy_state.c
@@ -0,0 +1,169 @@
+/*++
+/* NAME
+/*	tlsproxy_state 3
+/* SUMMARY
+/*	Postfix SMTP server
+/* SYNOPSIS
+/*	#include <tlsproxy.h>
+/*
+/*	TLSP_STATE *tlsp_state_create(service, plaintext_stream)
+/*	const char *service;
+/*	VSTREAM	*plaintext_stream;
+/*
+/*	void	tlsp_state_free(state)
+/*	TLSP_STATE *state;
+/* DESCRIPTION
+/*	This module provides TLSP_STATE constructor and destructor
+/*	routines.
+/*
+/*	tlsp_state_create() initializes session context.
+/*
+/*	tlsp_state_free() destroys session context. If the handshake
+/*	was in progress, it logs a 'handshake failed' message.
+/*
+/*	Arguments:
+/* .IP service
+/*	The service name for the TLS library. This argument is copied.
+/*	The destructor will automatically destroy the string.
+/* .IP plaintext_stream
+/*	The VSTREAM between postscreen(8) and tlsproxy(8).
+/*	The destructor will automatically close the stream.
+/* .PP
+/*	Other structure members are set by the application. The
+/*	text below describes how the TLSP_STATE destructor
+/*	disposes of them.
+/* .IP plaintext_buf
+/*	NBBIO for plaintext I/O.
+/*	The destructor will automatically turn off read/write/timeout
+/*	events and destroy the NBBIO.
+/* .IP ciphertext_fd
+/*	The file handle for the remote SMTP client socket.
+/*	The destructor will automatically turn off read/write events
+/*	and close the file handle.
+/* .IP ciphertext_timer
+/*	The destructor will automatically turn off this time event.
+/* .IP timeout
+/*	Time limit for plaintext and ciphertext I/O.
+/* .IP remote_endpt
+/*	Printable remote endpoint name.
+/*	The destructor will automatically destroy the string.
+/* .IP server_id
+/*	TLS session cache identifier.
+/*	The destructor will automatically destroy the string.
+/* DIAGNOSTICS
+/*	All errors are fatal.
+/* LICENSE
+/* .ad
+/* .fi
+/*	The Secure Mailer license must be distributed with this software.
+/* AUTHOR(S)
+/*	Wietse Venema
+/*	IBM T.J. Watson Research
+/*	P.O. Box 704
+/*	Yorktown Heights, NY 10598, USA
+/*
+/*	Wietse Venema
+/*	Google, Inc.
+/*	111 8th Avenue
+/*	New York, NY 10011, USA
+/*--*/
+
+ /*
+  * System library.
+  */
+#include <sys_defs.h>
+
+ /*
+  * Utility library.
+  */
+#include <msg.h>
+#include <mymalloc.h>
+#include <nbbio.h>
+
+ /*
+  * Master library.
+  */
+#include <mail_server.h>
+
+ /*
+  * TLS library.
+  */
+#ifdef USE_TLS
+#define TLS_INTERNAL			/* XXX */
+#include <tls.h>
+#include <tls_proxy.h>
+
+ /*
+  * Application-specific.
+  */
+#include <tlsproxy.h>
+
+/* tlsp_state_create - create TLS proxy state object */
+
+TLSP_STATE *tlsp_state_create(const char *service,
+			              VSTREAM *plaintext_stream)
+{
+    TLSP_STATE *state = (TLSP_STATE *) mymalloc(sizeof(*state));
+
+    state->flags = TLSP_FLAG_DO_HANDSHAKE;
+    state->service = mystrdup(service);
+    state->plaintext_stream = plaintext_stream;
+    state->plaintext_buf = 0;
+    state->ciphertext_fd = -1;
+    state->ciphertext_timer = 0;
+    state->timeout = -1;
+    state->remote_endpt = 0;
+    state->server_id = 0;
+    state->tls_context = 0;
+    state->tls_params = 0;
+    state->server_init_props = 0;
+    state->server_start_props = 0;
+    state->client_init_props = 0;
+    state->client_start_props = 0;
+
+    return (state);
+}
+
+/* tlsp_state_free - destroy state objects, connection and events */
+
+void    tlsp_state_free(TLSP_STATE *state)
+{
+    /* Don't log failure after plaintext EOF. */
+    if (state->remote_endpt && state->server_id
+	&& (state->flags & TLSP_FLAG_DO_HANDSHAKE))
+	msg_info("TLS handshake failed for service=%s peer=%s",
+		 state->server_id, state->remote_endpt);
+    myfree(state->service);
+    if (state->plaintext_buf)			/* turns off plaintext events */
+	nbbio_free(state->plaintext_buf);
+    else
+	event_disable_readwrite(vstream_fileno(state->plaintext_stream));
+    event_server_disconnect(state->plaintext_stream);
+    if (state->ciphertext_fd >= 0) {
+	event_disable_readwrite(state->ciphertext_fd);
+	(void) close(state->ciphertext_fd);
+    }
+    if (state->ciphertext_timer)
+	event_cancel_timer(state->ciphertext_timer, (void *) state);
+    if (state->remote_endpt) {
+	msg_info("DISCONNECT %s", state->remote_endpt);
+	myfree(state->remote_endpt);
+    }
+    if (state->server_id)
+	myfree(state->server_id);
+    if (state->tls_context)
+	tls_free_context(state->tls_context);
+    if (state->tls_params)
+	tls_proxy_client_param_free(state->tls_params);
+    if (state->server_init_props)
+	tls_proxy_server_init_free(state->server_init_props);
+    if (state->server_start_props)
+	tls_proxy_server_start_free(state->server_start_props);
+    if (state->client_init_props)
+	tls_proxy_client_init_free(state->client_init_props);
+    if (state->client_start_props)
+	tls_proxy_client_start_free(state->client_start_props);
+    myfree((void *) state);
+}
+
+#endif