smtp.c

   1 /*@ S-nail - a mail user agent derived from Berkeley Mail.
   2  *@ SMTP client.
   3  *@ TODO - use initial responses to save a round-trip (RFC 4954)
   4  *@ TODO - more (verbose) understanding+rection upon STATUS CODES
   5  *
   6  * Copyright (c) 2000-2004 Gunnar Ritter, Freiburg i. Br., Germany.
   7  * Copyright (c) 2012 - 2014 Steffen (Daode) Nurpmeso <sdaoden@users.sf.net>.
   8  */
   9 /*
  10  * Copyright (c) 2000
  11  * Gunnar Ritter.  All rights reserved.
  12  *
  13  * Redistribution and use in source and binary forms, with or without
  14  * modification, are permitted provided that the following conditions
  15  * are met:
  16  * 1. Redistributions of source code must retain the above copyright
  17  *    notice, this list of conditions and the following disclaimer.
  18  * 2. Redistributions in binary form must reproduce the above copyright
  19  *    notice, this list of conditions and the following disclaimer in the
  20  *    documentation and/or other materials provided with the distribution.
  21  * 3. All advertising materials mentioning features or use of this software
  22  *    must display the following acknowledgement:
  23  *    This product includes software developed by Gunnar Ritter
  24  *    and his contributors.
  25  * 4. Neither the name of Gunnar Ritter nor the names of his contributors
  26  *    may be used to endorse or promote products derived from this software
  27  *    without specific prior written permission.
  28  *
  29  * THIS SOFTWARE IS PROVIDED BY GUNNAR RITTER AND CONTRIBUTORS ``AS IS'' AND
  30  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  31  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  32  * ARE DISCLAIMED.  IN NO EVENT SHALL GUNNAR RITTER OR CONTRIBUTORS BE LIABLE
  33  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  34  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  35  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  36  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  37  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  38  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  39  * SUCH DAMAGE.
  40  */
  41
  42 #ifndef HAVE_AMALGAMATION
  43 # include "nail.h"
  44 #endif
  45
  46 EMPTY_FILE(smtp)
  47 #ifdef HAVE_SMTP
  48 #include <sys/socket.h>
  49
  50 #include <netdb.h>
  51
  52 #include <netinet/in.h>
  53
  54 #ifdef HAVE_ARPA_INET_H
  55 # include <arpa/inet.h>
  56 #endif
  57
  58 #undef NL
  59 #undef LINE
  60 #define NL        "\015\012"
  61 #define LINE(X)   X NL
  62
  63 struct smtp_line {
  64    char     *dat;    /* Actual data */
  65    size_t   datlen;
  66    char     *buf;    /* Memory buffer */
  67    size_t   bufsize;
  68 };
  69
  70 static sigjmp_buf _smtp_jmp;
  71
  72 static void    _smtp_onterm(int signo);
  73
  74 /* Get the SMTP server's answer, expecting val */
  75 static int     _smtp_read(struct sock *sp, struct smtp_line *slp, int val,
  76                   bool_t ign_eof, bool_t want_dat);
  77
  78 /* Talk to a SMTP server */
  79 static bool_t  _smtp_talk(struct sock *sp, struct sendbundle *sbp);
  80
  81 #ifdef HAVE_GSSAPI
  82 static bool_t  _smtp_gssapi(struct sock *sp, struct sendbundle *sbp,
  83                   struct smtp_line *slp);
  84 #endif
  85
  86 static void
  87 _smtp_onterm(int signo)
  88 {
  89    NYD_X; /* Signal handler */
  90    UNUSED(signo);
  91    siglongjmp(_smtp_jmp, 1);
  92 }
  93
  94 static int
  95 _smtp_read(struct sock *sp, struct smtp_line *slp, int val,
  96    bool_t ign_eof, bool_t want_dat)
  97 {
  98    int rv, len;
  99    char *cp;
 100    NYD_ENTER;
 101
 102    do {
 103       if ((len = sgetline(&slp->buf, &slp->bufsize, NULL, sp)) < 6) {
 104          if (len >= 0 && !ign_eof)
 105             fprintf(stderr, tr(241, "Unexpected EOF on SMTP connection\n"));
 106             rv = -1;
 107             goto jleave;
 108       }
 109       if (options & OPT_VERBOSE)
 110          fputs(slp->buf, stderr);
 111       switch (slp->buf[0]) {
 112       case '1':   rv = 1; break;
 113       case '2':   rv = 2; break;
 114       case '3':   rv = 3; break;
 115       case '4':   rv = 4; break;
 116       default:    rv = 5; break;
 117       }
 118       if (val != rv)
 119          fprintf(stderr, tr(191, "smtp-server: %s"), slp->buf);
 120    } while (slp->buf[3] == '-');
 121
 122    if (want_dat) {
 123       for (cp = slp->buf; digitchar(*cp); --len, ++cp)
 124          ;
 125       for (; blankchar(*cp); --len, ++cp)
 126          ;
 127       slp->dat = cp;
 128       assert(len >= 2);
 129       len -= 2;
 130       cp[slp->datlen = (size_t)len] = '\0';
 131    }
 132 jleave:
 133    NYD_LEAVE;
 134    return rv;
 135 }
 136
 137 /* Indirect SMTP I/O */
 138 #define _ANSWER(X, IGNEOF, WANTDAT) \
 139 do if (!(options & OPT_DEBUG)) {\
 140    int y;\
 141    if ((y = _smtp_read(sp, slp, X, IGNEOF, WANTDAT)) != (X) &&\
 142          (!(IGNEOF) || y != -1))\
 143       goto jleave;\
 144 } while (0)
 145 #define _OUT(X) \
 146 do {\
 147    if (options & OPT_VERBOSE)\
 148       fprintf(stderr, ">>> %s", X);\
 149    if (!(options & OPT_DEBUG))\
 150       swrite(sp, X);\
 151 } while (0)
 152
 153 static bool_t
 154 _smtp_talk(struct sock *sp, struct sendbundle *sbp)
 155 {
 156    char o[LINESIZE], *hostname, *cp;
 157    struct smtp_line _sl, *slp = &_sl;
 158    struct str b64;
 159    struct name *n;
 160    size_t blen, cnt;
 161    bool_t inhdr = TRU1, inbcc = FAL0, rv = FAL0;
 162    NYD_ENTER;
 163
 164    hostname = nodename(TRU1);
 165    slp->buf = NULL;
 166    slp->bufsize = 0;
 167
 168    /* Read greeting */
 169    _ANSWER(2, FAL0, FAL0);
 170
 171 #ifdef HAVE_SSL
 172    if (!sp->s_use_ssl && ok_blook(smtp_use_starttls)) {
 173       snprintf(o, sizeof o, LINE("EHLO %s"), hostname);
 174       _OUT(o);
 175       _ANSWER(2, FAL0, FAL0);
 176
 177       _OUT(LINE("STARTTLS"));
 178       _ANSWER(2, FAL0, FAL0);
 179
 180       if (!(options & OPT_DEBUG) &&
 181             ssl_open(sbp->sb_url.url_host.s, sp, sbp->sb_url.url_uhp.s) != OKAY)
 182          goto jleave;
 183    }
 184 #else
 185    if (ok_blook(smtp_use_starttls)) {
 186       fprintf(stderr, tr(225, "No SSL support compiled in.\n"));
 187       goto jleave;
 188    }
 189 #endif
 190
 191    /* Shorthand: no authentication, plain HELO? */
 192    if (sbp->sb_ccred.cc_authtype == AUTHTYPE_NONE) {
 193       snprintf(o, sizeof o, LINE("HELO %s"), hostname);
 194       _OUT(o);
 195       _ANSWER(2, FAL0, FAL0);
 196       goto jsend;
 197    }
 198
 199    /* We'll have to deal with authentication */
 200    snprintf(o, sizeof o, LINE("EHLO %s"), hostname);
 201    _OUT(o);
 202    _ANSWER(2, FAL0, FAL0);
 203
 204    switch (sbp->sb_ccred.cc_authtype) {
 205    default:
 206       /* FALLTHRU (doesn't happen) */
 207    case AUTHTYPE_PLAIN:
 208       _OUT(LINE("AUTH PLAIN"));
 209       _ANSWER(3, FAL0, FAL0);
 210
 211       snprintf(o, sizeof o, "%c%s%c%s",
 212          '\0', sbp->sb_ccred.cc_user.s, '\0', sbp->sb_ccred.cc_pass.s);
 213       b64_encode_buf(&b64, o,
 214          sbp->sb_ccred.cc_user.l + sbp->sb_ccred.cc_pass.l + 2,
 215          B64_SALLOC | B64_CRLF);
 216       _OUT(b64.s);
 217       _ANSWER(2, FAL0, FAL0);
 218       break;
 219    case AUTHTYPE_LOGIN:
 220       _OUT(LINE("AUTH LOGIN"));
 221       _ANSWER(3, FAL0, FAL0);
 222
 223       b64_encode_cp(&b64, sbp->sb_ccred.cc_user.s, B64_SALLOC | B64_CRLF);
 224       _OUT(b64.s);
 225       _ANSWER(3, FAL0, FAL0);
 226
 227       b64_encode_cp(&b64, sbp->sb_ccred.cc_pass.s, B64_SALLOC | B64_CRLF);
 228       _OUT(b64.s);
 229       _ANSWER(2, FAL0, FAL0);
 230       break;
 231 #ifdef HAVE_MD5
 232    case AUTHTYPE_CRAM_MD5:
 233       _OUT(LINE("AUTH CRAM-MD5"));
 234       _ANSWER(3, FAL0, TRU1);
 235       cp = cram_md5_string(sbp->sb_ccred.cc_user.s, sbp->sb_ccred.cc_pass.s,
 236             slp->dat);
 237       _OUT(cp);
 238       _ANSWER(2, FAL0, FAL0);
 239       break;
 240 #endif
 241 #ifdef HAVE_GSSAPI
 242    case AUTHTYPE_GSSAPI:
 243       if (!_smtp_gssapi(sp, sbp, slp))
 244          goto jleave;
 245       break;
 246 #endif
 247    }
 248
 249 jsend:
 250    snprintf(o, sizeof o, LINE("MAIL FROM:<%s>"), sbp->sb_url.url_uh.s);
 251    _OUT(o);
 252    _ANSWER(2, FAL0, FAL0);
 253
 254    for (n = sbp->sb_to; n != NULL; n = n->n_flink) {
 255       if (!(n->n_type & GDEL)) {
 256          snprintf(o, sizeof o, LINE("RCPT TO:<%s>"), skinned_name(n));
 257          _OUT(o);
 258          _ANSWER(2, FAL0, FAL0);
 259       }
 260    }
 261
 262    _OUT(LINE("DATA"));
 263    _ANSWER(3, FAL0, FAL0);
 264
 265    fflush_rewind(sbp->sb_input);
 266    cnt = fsize(sbp->sb_input);
 267    while (fgetline(&slp->buf, &slp->bufsize, &cnt, &blen, sbp->sb_input, 1)
 268          != NULL) {
 269       if (inhdr) {
 270          if (*slp->buf == '\n')
 271             inhdr = inbcc = FAL0;
 272          else if (inbcc && blankchar(*slp->buf))
 273             continue;
 274          /* We know what we have generated first, so do not look for whitespace
 275           * before the ':' */
 276          else if (!ascncasecmp(slp->buf, "bcc: ", 5)) {
 277             inbcc = TRU1;
 278             continue;
 279          } else
 280             inbcc = FAL0;
 281       }
 282
 283       if (*slp->buf == '.') {
 284          if (options & OPT_DEBUG)
 285             putc('.', stderr);
 286          else
 287             swrite1(sp, ".", 1, 1);
 288       }
 289       if (options & OPT_DEBUG) {
 290          fprintf(stderr, ">>> %s", slp->buf);
 291          continue;
 292       }
 293       slp->buf[blen - 1] = NL[0];
 294       slp->buf[blen] = NL[1];
 295       swrite1(sp, slp->buf, blen + 1, 1);
 296    }
 297    _OUT(LINE("."));
 298    _ANSWER(2, FAL0, FAL0);
 299
 300    _OUT(LINE("QUIT"));
 301    _ANSWER(2, TRU1, FAL0);
 302    rv = TRU1;
 303 jleave:
 304    if (slp->buf != NULL)
 305       free(slp->buf);
 306    NYD_LEAVE;
 307    return rv;
 308 }
 309
 310 #ifdef HAVE_GSSAPI
 311 # include "smtp_gssapi.h"
 312 #endif
 313
 314 #undef _OUT
 315 #undef _ANSWER
 316
 317 FL bool_t
 318 smtp_mta(struct sendbundle *sbp)
 319 {
 320    struct sock so;
 321    sighandler_type volatile saveterm;
 322    bool_t volatile rv = FAL0;
 323    NYD_ENTER;
 324
 325    saveterm = safe_signal(SIGTERM, SIG_IGN);
 326    if (sigsetjmp(_smtp_jmp, 1))
 327       goto jleave;
 328    if (saveterm != SIG_IGN)
 329       safe_signal(SIGTERM, &_smtp_onterm);
 330
 331    memset(&so, 0, sizeof so);
 332    if (!(options & OPT_DEBUG) && !sopen(&so, &sbp->sb_url))
 333       goto jleave;
 334
 335    so.s_desc = "SMTP";
 336    rv = _smtp_talk(&so, sbp);
 337
 338    if (!(options & OPT_DEBUG))
 339       sclose(&so);
 340 jleave:
 341    safe_signal(SIGTERM, saveterm);
 342    NYD_LEAVE;
 343    return rv;
 344 }
 345
 346 #undef LINE
 347 #undef NL
 348 #endif /* HAVE_SMTP */
 349
 350 /* vim:set fenc=utf-8:s-it-mode */