1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) The Exim Maintainers 2020 - 2023 */
6 /* Copyright (c) University of Cambridge 1995 - 2018 */
7 /* See the file NOTICE for conditions of use and distribution. */
8 /* SPDX-License-Identifier: GPL-2.0-or-later */
10 /* This module provides TLS (aka SSL) support for Exim. The code for OpenSSL is
11 based on a patch that was originally contributed by Steve Haslam. It was
12 adapted from stunnel, a GPL program by Michal Trojnara. The code for GNU TLS is
13 based on a patch contributed by Nikos Mavrogiannopoulos. Because these packages
14 are so very different, the functions for each are kept in separate files. The
15 relevant file is #included as required, after any any common functions.
17 No cryptographic code is included in Exim. All this module does is to call
18 functions from the OpenSSL or GNU TLS libraries. */
22 #include "transports/smtp.h"
24 #if !defined(DISABLE_TLS) && !defined(USE_OPENSSL) && !defined(USE_GNUTLS)
25 # error One of USE_OPENSSL or USE_GNUTLS must be defined for a TLS build
29 #if defined(MACRO_PREDEF) && !defined(DISABLE_TLS)
30 # include "macro_predef.h"
34 # include "tls-openssl.c"
40 static void tls_per_lib_daemon_init(void);
41 static void tls_per_lib_daemon_tick(void);
42 static unsigned tls_server_creds_init(void);
43 static void tls_server_creds_invalidate(void);
44 static void tls_client_creds_init(transport_instance *, BOOL);
45 static void tls_client_creds_invalidate(transport_instance *);
46 static void tls_daemon_creds_reload(void);
47 static BOOL opt_set_and_noexpand(const uschar *);
48 static BOOL opt_unset_or_noexpand(const uschar *);
52 /* This module is compiled only when it is specifically requested in the
53 build-time configuration. However, some compilers don't like compiling empty
54 modules, so keep them happy with a dummy when skipping the rest. Make it
55 reference itself to stop picky compilers complaining that it is unused, and put
56 in a dummy argument to stop even pickier compilers complaining about infinite
60 static void dummy(int x) { dummy(x-1); }
61 #else /* most of the rest of the file */
63 const exim_tlslib_state null_tls_preload = {0};
65 /* Static variables that are used for buffering data by both sets of
66 functions and the common functions below.
68 We're moving away from this; GnuTLS is already using a state, which
69 can switch, so we can do TLS callouts during ACLs. */
71 static const int ssl_xfer_buffer_size = 4096;
73 static uschar *ssl_xfer_buffer = NULL;
74 static int ssl_xfer_buffer_lwm = 0;
75 static int ssl_xfer_buffer_hwm = 0;
76 static int ssl_xfer_eof = FALSE;
77 static BOOL ssl_xfer_error = FALSE;
80 #ifdef EXIM_HAVE_KEVENT
81 # define KEV_SIZE 16 /* Eight file,dir pairs */
82 static struct kevent kev[KEV_SIZE];
83 static int kev_used = 0;
86 static unsigned tls_creds_expire = 0;
88 /*************************************************
89 * Expand string; give error on failure *
90 *************************************************/
92 /* If expansion is forced to fail, set the result NULL and return TRUE.
93 Other failures return FALSE. For a server, an SMTP response is given.
96 s the string to expand; if NULL just return TRUE
97 name name of string being expanded (for error)
98 result where to put the result
100 Returns: TRUE if OK; result may still be NULL after forced failure
104 expand_check(const uschar * s, const uschar * name,
105 uschar ** result, uschar ** errstr)
109 f.expand_string_forcedfail = FALSE;
112 else if ( !(*result = expand_string(US s)) /* need to clean up const more */
113 && !f.expand_string_forcedfail
116 *errstr = US"Internal error";
117 log_write(0, LOG_MAIN|LOG_PANIC, "expansion of %s failed: %s", name,
118 expand_string_message);
125 #if defined(EXIM_HAVE_INOTIFY) || defined(EXIM_HAVE_KEVENT)
126 /* Add the directory for a filename to the inotify handle, creating that if
127 needed. This is enough to see changes to files in that dir.
128 Return boolean success.
130 The word "system" fails, which is on the safe side as we don't know what
131 directory it implies nor if the TLS library handles a watch for us.
133 The string "system,cache" is recognised and explicitly accepted without
134 setting a watch. This permits the system CA bundle to be cached even though
135 we have no way to tell when it gets modified by an update.
136 The call chain for OpenSSL uses a (undocumented) call into the library
137 to discover the actual file. We don't know what GnuTLS uses.
139 A full set of caching including the CAs takes 35ms output off of the
140 server tls_init() (GnuTLS, Fedora 32, 2018-class x86_64 laptop hardware).
143 tls_set_one_watch(const uschar * filename)
144 # ifdef EXIM_HAVE_INOTIFY
146 uschar buf[PATH_MAX];
150 if (Ustrcmp(filename, "system,cache") == 0) return TRUE;
151 if (!(s = Ustrrchr(filename, '/'))) return FALSE;
153 for (unsigned loop = 20;
154 (len = readlink(CCS filename, CS buf, sizeof(buf))) >= 0; )
156 if (--loop == 0) { errno = ELOOP; return FALSE; }
157 filename = buf[0] == '/'
158 ? string_copyn(buf, (unsigned)len) /* mem released by tls_set_watch */
159 : string_sprintf("%.*s/%.*s", (int)(s - filename), filename, (int)len, buf);
160 s = Ustrrchr(filename, '/');
163 return FALSE; /* other error */
166 s = string_copyn(filename, s - filename); /* mem released by tls_set_watch */
168 DEBUG(D_tls) debug_printf("watch dir '%s'\n", s);
170 if (inotify_add_watch(tls_watch_fd, CCS s,
171 IN_ONESHOT | IN_CLOSE_WRITE | IN_DELETE | IN_DELETE_SELF
172 | IN_MOVED_FROM | IN_MOVED_TO | IN_MOVE_SELF) >= 0)
174 DEBUG(D_tls) debug_printf("notify_add_watch: %s\n", strerror(errno));
178 # ifdef EXIM_HAVE_KEVENT
181 int fd1, fd2, i, j, cnt = 0;
184 struct kevent k_dummy;
185 struct timespec ts = {0};
189 if (Ustrcmp(filename, "system,cache") == 0) return TRUE;
193 if (kev_used > KEV_SIZE-2) { s = US"out of kev space"; goto bad; }
194 if (!(s = Ustrrchr(filename, '/'))) return FALSE;
195 s = string_copyn(filename, s - filename); /* mem released by tls_set_watch */
197 /* The dir open will fail if there is a symlink on the path. Fine; it's too
198 much effort to handle all possible cases; just refuse the preload. */
200 if ((fd2 = open(CCS s, O_RDONLY | O_NOFOLLOW)) < 0) { s = US"open dir"; goto bad; }
202 if ((lstat(CCS filename, &sb)) < 0) { s = US"lstat"; goto bad; }
203 if (!S_ISLNK(sb.st_mode))
205 if ((fd1 = open(CCS filename, O_RDONLY | O_NOFOLLOW)) < 0)
206 { s = US"open file"; goto bad; }
207 DEBUG(D_tls) debug_printf("watch file '%s':\t%d\n", filename, fd1);
208 EV_SET(&kev[kev_used++],
211 EV_ADD | EV_ENABLE | EV_ONESHOT,
212 NOTE_DELETE | NOTE_WRITE | NOTE_EXTEND
213 | NOTE_ATTRIB | NOTE_RENAME | NOTE_REVOKE,
218 DEBUG(D_tls) debug_printf("watch dir '%s':\t%d\n", s, fd2);
219 EV_SET(&kev[kev_used++],
222 EV_ADD | EV_ENABLE | EV_ONESHOT,
223 NOTE_DELETE | NOTE_WRITE | NOTE_EXTEND
224 | NOTE_ATTRIB | NOTE_RENAME | NOTE_REVOKE,
229 if (!(S_ISLNK(sb.st_mode))) break;
231 t = store_get(1024, GET_UNTAINTED);
232 Ustrncpy(t, s, 1022);
235 if ((i = readlink(CCS filename, (void *)(t+j), 1023-j)) < 0) { s = US"readlink"; goto bad; }
238 store_release_above(t+1);
242 if (kevent(tls_watch_fd, &kev[kev_used-cnt], cnt, &k_dummy, 1, &ts) >= 0)
245 if (kevent(tls_watch_fd, &kev[kev_used-cnt], cnt, NULL, 0, NULL) >= 0)
253 debug_printf("%s: %s: %s\n", __FUNCTION__, s, strerror(errno));
255 debug_printf("%s: %s\n", __FUNCTION__, s);
258 # endif /*EXIM_HAVE_KEVENT*/
261 /* Create an inotify facility if needed.
262 Then set watches on the dir containing the given file or (optionally)
263 list of files. Return boolean success. */
266 tls_set_watch(const uschar * filename, BOOL list)
271 if (!filename || !*filename) return TRUE;
272 if (Ustrncmp(filename, "system", 6) == 0) return TRUE;
274 DEBUG(D_tls) debug_printf("tls_set_watch: '%s'\n", filename);
276 if ( tls_watch_fd < 0
277 # ifdef EXIM_HAVE_INOTIFY
278 && (tls_watch_fd = inotify_init1(O_CLOEXEC)) < 0
280 # ifdef EXIM_HAVE_KEVENT
281 && (tls_watch_fd = kqueue()) < 0
285 DEBUG(D_tls) debug_printf("inotify_init: %s\n", strerror(errno));
294 for (uschar * s; s = string_nextinlist(&filename, &sep, NULL, 0); )
295 if (!(rc = tls_set_one_watch(s))) break;
298 rc = tls_set_one_watch(filename);
301 if (!rc) DEBUG(D_tls) debug_printf("tls_set_watch() fail on '%s': %s\n", filename, strerror(errno));
307 tls_watch_discard_event(int fd)
309 #ifdef EXIM_HAVE_INOTIFY
310 (void) read(fd, big_buffer, big_buffer_size);
312 #ifdef EXIM_HAVE_KEVENT
314 struct timespec t = {0};
315 (void) kevent(fd, NULL, 0, &kev, 1, &t);
318 #endif /*EXIM_HAVE_INOTIFY*/
322 tls_client_creds_reload(BOOL watch)
324 for(transport_instance * t = transports; t; t = t->next)
325 if (Ustrcmp(t->driver_name, "smtp") == 0)
327 tls_client_creds_invalidate(t);
328 tls_client_creds_init(t, watch);
334 tls_watch_invalidate(void)
336 if (tls_watch_fd < 0) return;
338 #ifdef EXIM_HAVE_KEVENT
339 /* Close the files we had open for kevent */
340 for (int i = 0; i < kev_used; i++)
342 DEBUG(D_tls) debug_printf("closing watch fd: %d\n", (int) kev[i].ident);
343 (void) close((int) kev[i].ident);
344 kev[i].ident = (uintptr_t)-1;
355 tls_daemon_creds_reload(void)
359 #ifdef EXIM_HAVE_KEVENT
360 tls_watch_invalidate();
363 tls_server_creds_invalidate();
365 /* _expire is for a time-limited selfsign server cert */
366 tls_creds_expire = (lifetime = tls_server_creds_init())
367 ? time(NULL) + lifetime : 0;
369 tls_client_creds_reload(TRUE);
373 /* Utility predicates for use by the per-library code */
375 opt_set_and_noexpand(const uschar * opt)
376 { return opt && *opt && Ustrchr(opt, '$') == NULL; }
379 opt_unset_or_noexpand(const uschar * opt)
380 { return !opt || Ustrchr(opt, '$') == NULL; }
384 /* Called every time round the daemon loop.
386 If we reloaded fd-watcher, return the old watch fd
387 having modified the global for the new one. Otherwise
392 tls_daemon_tick(void)
394 int old_watch_fd = tls_watch_fd;
396 tls_per_lib_daemon_tick();
397 #if defined(EXIM_HAVE_INOTIFY) || defined(EXIM_HAVE_KEVENT)
398 if (tls_creds_expire && time(NULL) >= tls_creds_expire)
400 /* The server cert is a selfsign, with limited lifetime. Dump it and
401 generate a new one. Reload the rest of the creds also as the machinery
404 DEBUG(D_tls) debug_printf("selfsign cert rotate\n");
405 tls_creds_expire = 0;
406 tls_daemon_creds_reload();
409 else if (tls_watch_trigger_time && time(NULL) >= tls_watch_trigger_time + 5)
411 /* Called, after a delay for multiple file ops to get done, from
412 the daemon when any of the watches added (above) fire.
413 Dump the set of watches and arrange to reload cached creds (which
414 will set up new watches). */
416 DEBUG(D_tls) debug_printf("watch triggered\n");
417 tls_watch_trigger_time = tls_creds_expire = 0;
418 tls_daemon_creds_reload();
425 /* Called once at daemon startup */
428 tls_daemon_init(void)
430 tls_per_lib_daemon_init();
434 /*************************************************
435 * Timezone environment flipping *
436 *************************************************/
441 uschar * old = US getenv("TZ");
442 (void) setenv("TZ", CCS tz, 1);
448 restore_tz(uschar * tz)
451 (void) setenv("TZ", CCS tz, 1);
453 (void) os_unsetenv(US"TZ");
457 /*************************************************
458 * Many functions are package-specific *
459 *************************************************/
461 static void tls_client_resmption_key(tls_support *, smtp_connect_args *,
462 smtp_transport_options_block *);
466 # include "tls-gnu.c"
467 # include "tlscert-gnu.c"
468 # define ssl_xfer_buffer (state_server.xfer_buffer)
469 # define ssl_xfer_buffer_lwm (state_server.xfer_buffer_lwm)
470 # define ssl_xfer_buffer_hwm (state_server.xfer_buffer_hwm)
471 # define ssl_xfer_eof (state_server.xfer_eof)
472 # define ssl_xfer_error (state_server.xfer_error)
476 # include "tls-openssl.c"
477 # include "tlscert-openssl.c"
482 /*************************************************
483 * TLS version of ungetc *
484 *************************************************/
486 /* Puts a character back in the input buffer. Only ever
488 Only used by the server-side TLS.
493 Returns: the character
499 if (ssl_xfer_buffer_lwm <= 0)
500 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "buffer underflow in tls_ungetc");
502 ssl_xfer_buffer[--ssl_xfer_buffer_lwm] = ch;
508 /*************************************************
509 * TLS version of feof *
510 *************************************************/
512 /* Tests for a previous EOF
513 Only used by the server-side TLS.
516 Returns: non-zero if the eof flag is set
522 return (int)ssl_xfer_eof;
527 /*************************************************
528 * TLS version of ferror *
529 *************************************************/
531 /* Tests for a previous read error, and returns with errno
532 restored to what it was when the error was detected.
533 Only used by the server-side TLS.
535 >>>>> Hmm. Errno not handled yet. Where do we get it from? >>>>>
538 Returns: non-zero if the error flag is set
544 return (int)ssl_xfer_error;
548 /*************************************************
549 * TLS version of smtp_buffered *
550 *************************************************/
552 /* Tests for unused chars in the TLS input buffer.
553 Only used by the server-side TLS.
560 tls_smtp_buffered(void)
562 return ssl_xfer_buffer_lwm < ssl_xfer_buffer_hwm;
566 #endif /*DISABLE_TLS*/
569 tls_modify_variables(tls_support * dest_tsp)
571 modify_variable(US"tls_bits", &dest_tsp->bits);
572 modify_variable(US"tls_certificate_verified", &dest_tsp->certificate_verified);
573 modify_variable(US"tls_cipher", &dest_tsp->cipher);
574 modify_variable(US"tls_peerdn", &dest_tsp->peerdn);
576 modify_variable(US"tls_sni", &dest_tsp->sni);
582 /************************************************
583 * TLS certificate name operations *
584 ************************************************/
586 /* Convert an rfc4514 DN to an exim comma-sep list.
587 Backslashed commas need to be replaced by doublecomma
588 for Exim's list quoting. We modify the given string
593 dn_to_list(uschar * dn)
595 for (uschar * cp = dn; *cp; cp++)
596 if (cp[0] == '\\' && cp[1] == ',')
601 /* Extract fields of a given type from an RFC4514-
602 format Distinguished Name. Return an Exim list.
603 NOTE: We modify the supplied dn string during operation.
606 dn Distinguished Name string
607 mod list containing optional output list-sep and
608 field selector match, comma-separated
610 allocated string with list of matching fields,
615 tls_field_from_dn(uschar * dn, const uschar * mod)
618 uschar outsep = '\n';
620 uschar * match = NULL;
622 gstring * list = NULL;
624 while ((ele = string_nextinlist(&mod, &insep, NULL, 0)))
626 match = ele; /* field tag to match */
628 outsep = ele[1]; /* nondefault output separator */
632 len = match ? Ustrlen(match) : -1;
633 while ((ele = string_nextinlist(CUSS &dn, &insep, NULL, 0)))
635 || Ustrncmp(ele, match, len) == 0 && ele[len] == '='
637 list = string_append_listele(list, outsep, ele+len+1);
638 return string_from_gstring(list);
642 /* Compare a domain name with a possibly-wildcarded name. Wildcards
643 are restricted to a single one, as the first element of patterns
644 having at least three dot-separated elements. Case-independent.
645 Return TRUE for a match
648 is_name_match(const uschar * name, const uschar * pat)
651 return *pat == '*' /* possible wildcard match */
652 ? *++pat == '.' /* starts star, dot */
653 && !Ustrchr(++pat, '*') /* has no more stars */
654 && Ustrchr(pat, '.') /* and has another dot. */
655 && (cp = Ustrchr(name, '.'))/* The name has at least one dot */
656 && strcmpic(++cp, pat) == 0 /* and we only compare after it. */
657 : !Ustrchr(pat+1, '*')
658 && strcmpic(name, pat) == 0;
661 /* Compare a list of names with the dnsname elements
662 of the Subject Alternate Name, if any, and the
666 namelist names to compare
674 tls_is_name_for_cert(const uschar * namelist, void * cert)
676 uschar * altnames, * subjdn, * certname, * cmpname;
679 if ((altnames = tls_cert_subject_altname(cert, US"dns")))
682 DEBUG(D_tls|D_lookup) debug_printf_indent("cert has SAN\n");
683 while ((cmpname = string_nextinlist(&namelist, &cmp_sep, NULL, 0)))
685 const uschar * an = altnames;
686 DEBUG(D_tls|D_lookup) debug_printf_indent(" %s in SANs?", cmpname);
687 while ((certname = string_nextinlist(&an, &alt_sep, NULL, 0)))
688 if (is_name_match(cmpname, certname))
690 DEBUG(D_tls|D_lookup) debug_printf_indent(" yes (matched %s)\n", certname);
693 DEBUG(D_tls|D_lookup) debug_printf_indent(" no (end of SAN list)\n");
697 else if ((subjdn = tls_cert_subject(cert, NULL)))
702 while ((cmpname = string_nextinlist(&namelist, &cmp_sep, NULL, 0)))
704 const uschar * sn = subjdn;
705 DEBUG(D_tls|D_lookup) debug_printf_indent(" %s in SN?", cmpname);
706 while ((certname = string_nextinlist(&sn, &sn_sep, NULL, 0)))
707 if ( *certname++ == 'C'
708 && *certname++ == 'N'
709 && *certname++ == '='
710 && is_name_match(cmpname, certname)
713 DEBUG(D_tls|D_lookup) debug_printf_indent(" yes (matched %s)\n", certname);
716 DEBUG(D_tls|D_lookup) debug_printf_indent(" no (end of CN)\n");
722 /* Environment cleanup: The GnuTLS library uses SSLKEYLOGFILE in the environment
723 and writes a file by that name. Our OpenSSL code does the same, using keying
724 info from the library API.
725 The GnuTLS support only works if exim is run by root, not taking advantage of
727 You can use either the external environment (modulo the keep_environment config)
728 or the add_environment config option for SSLKEYLOGFILE; the latter takes
731 If the path is absolute, require it starts with the spooldir; otherwise delete
732 the env variable. If relative, prefix the spooldir.
737 uschar * path = US getenv("SSLKEYLOGFILE");
740 unsetenv("SSLKEYLOGFILE");
741 else if (*path != '/')
744 debug_printf("prepending spooldir to env SSLKEYLOGFILE\n");
745 setenv("SSLKEYLOGFILE", CCS string_sprintf("%s/%s", spool_directory, path), 1);
747 else if (Ustrncmp(path, spool_directory, Ustrlen(spool_directory)) != 0)
750 debug_printf("removing env SSLKEYLOGFILE=%s: not under spooldir\n", path);
751 unsetenv("SSLKEYLOGFILE");
755 /*************************************************
756 * Drop privs for checking TLS config *
757 *************************************************/
759 /* We want to validate TLS options during readconf, but do not want to be
760 root when we call into the TLS library, in case of library linkage errors
761 which cause segfaults; before this check, those were always done as the Exim
762 runtime user and it makes sense to continue with that.
764 Assumes: tls_require_ciphers has been set, if it will be
765 exim_user has been set, if it will be
766 exim_group has been set, if it will be
768 Returns: bool for "okay"; false will cause caller to immediately exit.
772 tls_dropprivs_validate_require_cipher(BOOL nowarn)
774 const uschar *errmsg;
777 void (*oldsignal)(int);
779 /* If TLS will never be used, no point checking ciphers */
781 if ( !tls_advertise_hosts
782 || !*tls_advertise_hosts
783 || Ustrcmp(tls_advertise_hosts, ":") == 0
786 else if (!nowarn && !tls_certificate)
787 log_write(0, LOG_MAIN,
788 "Warning: No server certificate defined; will use a selfsigned one.\n"
789 " Suggested action: either install a certificate or change tls_advertise_hosts option");
791 oldsignal = signal(SIGCHLD, SIG_DFL);
794 if ((pid = exim_fork(US"cipher-validate")) < 0)
795 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "fork failed for TLS check");
799 /* in some modes, will have dropped privilege already */
801 exim_setugid(exim_uid, exim_gid, FALSE,
802 US"calling tls_validate_require_cipher");
804 if ((errmsg = tls_validate_require_cipher()))
805 log_write(0, LOG_PANIC_DIE|LOG_CONFIG,
806 "tls_require_ciphers invalid: %s", errmsg);
808 exim_underbar_exit(EXIT_SUCCESS);
812 rc = waitpid(pid, &status, 0);
813 } while (rc < 0 && errno == EINTR);
816 debug_printf("tls_validate_require_cipher child %d ended: status=0x%x\n",
819 signal(SIGCHLD, oldsignal);
828 tls_client_resmption_key(tls_support * tlsp, smtp_connect_args * conn_args,
829 smtp_transport_options_block * ob)
831 #ifndef DISABLE_TLS_RESUME
832 hctx * h = &tlsp->resume_hctx;
836 DEBUG(D_tls) if (conn_args->host_lbserver)
837 debug_printf("TLS: lbserver '%s'\n", conn_args->host_lbserver);
839 # ifdef EXIM_HAVE_SHA2
840 exim_sha_init(h, HASH_SHA2_256);
842 exim_sha_init(h, HASH_SHA1);
844 exim_sha_update_string(h, conn_args->host_lbserver);
847 exim_sha_update(h, CUS &conn_args->tlsa_dnsa, sizeof(dns_answer));
849 exim_sha_update_string(h, conn_args->host->address);
850 exim_sha_update(h, CUS &conn_args->host->port, sizeof(conn_args->host->port));
851 exim_sha_update_string(h, conn_args->sending_ip_address);
852 exim_sha_update_string(h, openssl_options);
853 exim_sha_update_string(h, ob->tls_require_ciphers);
854 exim_sha_update_string(h, tlsp->sni);
855 # ifdef EXIM_HAVE_ALPN
856 exim_sha_update_string(h, ob->tls_alpn);
858 exim_sha_finish(h, &b);
859 for (g = string_get(b.len*2+1); b.len-- > 0; )
860 g = string_fmt_append(g, "%02x", *b.data++);
861 tlsp->resume_index = string_from_gstring(g);
862 DEBUG(D_tls) debug_printf("TLS: resume session index %s\n", tlsp->resume_index);
868 /* Start TLS as a client for an ajunct connection, eg. readsocket
869 Return boolean success.
873 tls_client_adjunct_start(host_item * host, client_conn_ctx * cctx,
874 const uschar * sni, uschar ** errmsg)
876 union sockaddr_46 interface_sock;
877 EXIM_SOCKLEN_T size = sizeof(interface_sock);
878 smtp_connect_args conn_args = {.host = host };
879 tls_support tls_dummy = { .sni = NULL };
882 if (getsockname(cctx->sock, (struct sockaddr *) &interface_sock, &size) == 0)
883 conn_args.sending_ip_address = host_ntoa(-1, &interface_sock, NULL, NULL);
886 *errmsg = string_sprintf("getsockname failed: %s", strerror(errno));
890 /* To handle SNI we need to emulate more of a real transport because the
891 base tls code assumes that is where the SNI string lives. */
895 transport_instance * tb;
896 smtp_transport_options_block * ob;
898 conn_args.tblock = tb = store_get(sizeof(*tb), GET_UNTAINTED);
899 memset(tb, 0, sizeof(*tb));
901 tb->options_block = ob = store_get(sizeof(*ob), GET_UNTAINTED);
902 memcpy(ob, &smtp_transport_option_defaults, sizeof(*ob));
907 if (!tls_client_start(cctx, &conn_args, NULL, &tls_dummy, &errstr))
909 *errmsg = string_sprintf("TLS connect failed: %s", errstr);
917 #endif /*!DISABLE_TLS*/
918 #endif /*!MACRO_PREDEF*/