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 - 2018 Steffen (Daode) Nurpmeso <steffen@sdaoden.eu>.
   8  * SPDX-License-Identifier: BSD-4-Clause
   9  */
  10 /*
  11  * Copyright (c) 2000
  12  * Gunnar Ritter.  All rights reserved.
  13  *
  14  * Redistribution and use in source and binary forms, with or without
  15  * modification, are permitted provided that the following conditions
  16  * are met:
  17  * 1. Redistributions of source code must retain the above copyright
  18  *    notice, this list of conditions and the following disclaimer.
  19  * 2. Redistributions in binary form must reproduce the above copyright
  20  *    notice, this list of conditions and the following disclaimer in the
  21  *    documentation and/or other materials provided with the distribution.
  22  * 3. All advertising materials mentioning features or use of this software
  23  *    must display the following acknowledgement:
  24  *    This product includes software developed by Gunnar Ritter
  25  *    and his contributors.
  26  * 4. Neither the name of Gunnar Ritter nor the names of his contributors
  27  *    may be used to endorse or promote products derived from this software
  28  *    without specific prior written permission.
  29  *
  30  * THIS SOFTWARE IS PROVIDED BY GUNNAR RITTER AND CONTRIBUTORS ``AS IS'' AND
  31  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  32  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  33  * ARE DISCLAIMED.  IN NO EVENT SHALL GUNNAR RITTER OR CONTRIBUTORS BE LIABLE
  34  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  35  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  36  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  37  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  38  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  39  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  40  * SUCH DAMAGE.
  41  */
  42 #undef n_FILE
  43 #define n_FILE smtp
  44
  45 #ifndef HAVE_AMALGAMATION
  46 # include "nail.h"
  47 #endif
  48
  49 EMPTY_FILE()
  50 #ifdef HAVE_SMTP
  51 #include <sys/socket.h>
  52
  53 struct smtp_line {
  54    char     *dat;    /* Actual data */
  55    size_t   datlen;
  56    char     *buf;    /* Memory buffer */
  57    size_t   bufsize;
  58 };
  59
  60 static sigjmp_buf _smtp_jmp;
  61
  62 static void    _smtp_onterm(int signo);
  63
  64 /* Get the SMTP server's answer, expecting val */
  65 static int     _smtp_read(struct sock *sp, struct smtp_line *slp, int val,
  66                   bool_t ign_eof, bool_t want_dat);
  67
  68 /* Talk to a SMTP server */
  69 static bool_t  _smtp_talk(struct sock *sp, struct sendbundle *sbp);
  70
  71 #ifdef HAVE_GSSAPI
  72 static bool_t  _smtp_gssapi(struct sock *sp, struct sendbundle *sbp,
  73                   struct smtp_line *slp);
  74 #endif
  75
  76 static void
  77 _smtp_onterm(int signo)
  78 {
  79    NYD_X; /* Signal handler */
  80    n_UNUSED(signo);
  81    siglongjmp(_smtp_jmp, 1);
  82 }
  83
  84 static int
  85 _smtp_read(struct sock *sp, struct smtp_line *slp, int val,
  86    bool_t ign_eof, bool_t want_dat)
  87 {
  88    int rv, len;
  89    char *cp;
  90    NYD_ENTER;
  91
  92    do {
  93       if ((len = sgetline(&slp->buf, &slp->bufsize, NULL, sp)) < 6) {
  94          if (len >= 0 && !ign_eof)
  95             n_err(_("Unexpected EOF on SMTP connection\n"));
  96          rv = -1;
  97          goto jleave;
  98       }
  99       if (n_poption & n_PO_VERBVERB)
 100          n_err(slp->buf);
 101       switch (slp->buf[0]) {
 102       case '1':   rv = 1; break;
 103       case '2':   rv = 2; break;
 104       case '3':   rv = 3; break;
 105       case '4':   rv = 4; break;
 106       default:    rv = 5; break;
 107       }
 108       if (val != rv)
 109          n_err(_("smtp-server: %s"), slp->buf);
 110    } while (slp->buf[3] == '-');
 111
 112    if (want_dat) {
 113       for (cp = slp->buf; digitchar(*cp); --len, ++cp)
 114          ;
 115       for (; blankchar(*cp); --len, ++cp)
 116          ;
 117       slp->dat = cp;
 118       assert(len >= 2);
 119       len -= 2;
 120       cp[slp->datlen = (size_t)len] = '\0';
 121    }
 122 jleave:
 123    NYD_LEAVE;
 124    return rv;
 125 }
 126
 127 /* Indirect SMTP I/O */
 128 #define _ANSWER(X, IGNEOF, WANTDAT) \
 129 do if (!(n_poption & n_PO_DEBUG)) {\
 130    int y;\
 131    if ((y = _smtp_read(sp, slp, X, IGNEOF, WANTDAT)) != (X) &&\
 132          (!(IGNEOF) || y != -1))\
 133       goto jleave;\
 134 } while (0)
 135 #define _OUT(X) \
 136 do {\
 137    if (n_poption & n_PO_D_VV){\
 138       /* TODO for now n_err() cannot normalize newlines in %s expansions */\
 139       char *__x__ = savestr(X), *__y__ = &__x__[strlen(__x__)];\
 140       while(__y__ > __x__ && (__y__[-1] == '\n' || __y__[-1] == '\r'))\
 141          --__y__;\
 142       *__y__ = '\0';\
 143       n_err(">>> %s\n", __x__);\
 144    }\
 145    if (!(n_poption & n_PO_DEBUG))\
 146       swrite(sp, X);\
 147 } while (0)
 148
 149 static bool_t
 150 _smtp_talk(struct sock *sp, struct sendbundle *sbp) /* TODO n_string etc. */
 151 {
 152    char o[LINESIZE];
 153    char const *hostname;
 154    struct smtp_line _sl, *slp = &_sl;
 155    struct str b64;
 156    struct name *n;
 157    size_t blen, cnt;
 158    bool_t inhdr = TRU1, inbcc = FAL0, rv = FAL0;
 159    NYD_ENTER;
 160
 161    hostname = n_nodename(TRU1);
 162    slp->buf = NULL;
 163    slp->bufsize = 0;
 164
 165    /* Read greeting */
 166    _ANSWER(2, FAL0, FAL0);
 167
 168 #ifdef HAVE_TLS
 169    if (!sp->s_use_tls && xok_blook(smtp_use_starttls, &sbp->sb_url, OXM_ALL)) {
 170       snprintf(o, sizeof o, NETLINE("EHLO %s"), hostname);
 171       _OUT(o);
 172       _ANSWER(2, FAL0, FAL0);
 173
 174       _OUT(NETLINE("STARTTLS"));
 175       _ANSWER(2, FAL0, FAL0);
 176
 177       if(!(n_poption & n_PO_DEBUG) && !n_tls_open(&sbp->sb_url, sp))
 178          goto jleave;
 179    }
 180 #else
 181    if (xok_blook(smtp_use_starttls, &sbp->sb_url, OXM_ALL)) {
 182       n_err(_("No TLS support compiled in\n"));
 183       goto jleave;
 184    }
 185 #endif
 186
 187    /* Shorthand: no authentication, plain HELO? */
 188    if (sbp->sb_ccred.cc_authtype == AUTHTYPE_NONE) {
 189       snprintf(o, sizeof o, NETLINE("HELO %s"), hostname);
 190       _OUT(o);
 191       _ANSWER(2, FAL0, FAL0);
 192       goto jsend;
 193    }
 194
 195    /* We'll have to deal with authentication */
 196    snprintf(o, sizeof o, NETLINE("EHLO %s"), hostname);
 197    _OUT(o);
 198    _ANSWER(2, FAL0, FAL0);
 199
 200    switch (sbp->sb_ccred.cc_authtype) {
 201    default:
 202       /* FALLTHRU (doesn't happen) */
 203    case AUTHTYPE_PLAIN:
 204       cnt = sbp->sb_ccred.cc_user.l;
 205       if(sbp->sb_ccred.cc_pass.l >= UIZ_MAX - 2 ||
 206             cnt >= UIZ_MAX - 2 - sbp->sb_ccred.cc_pass.l){
 207 jerr_cred:
 208          n_err(_("Credentials overflow buffer sizes\n"));
 209          goto jleave;
 210       }
 211       cnt += sbp->sb_ccred.cc_pass.l;
 212
 213       if(cnt >= sizeof(o) - 2)
 214          goto jerr_cred;
 215       cnt += 2;
 216       if(b64_encode_calc_size(cnt) == UIZ_MAX)
 217          goto jerr_cred;
 218
 219       _OUT(NETLINE("AUTH PLAIN"));
 220       _ANSWER(3, FAL0, FAL0);
 221
 222       snprintf(o, sizeof o, "%c%s%c%s",
 223          '\0', sbp->sb_ccred.cc_user.s, '\0', sbp->sb_ccred.cc_pass.s);
 224       if(b64_encode_buf(&b64, o, cnt, B64_SALLOC | B64_CRLF) == NULL)
 225          goto jleave;
 226       _OUT(b64.s);
 227       _ANSWER(2, FAL0, FAL0);
 228       break;
 229    case AUTHTYPE_LOGIN:
 230       if(b64_encode_calc_size(sbp->sb_ccred.cc_user.l) == UIZ_MAX ||
 231             b64_encode_calc_size(sbp->sb_ccred.cc_pass.l) == UIZ_MAX)
 232          goto jerr_cred;
 233
 234       _OUT(NETLINE("AUTH LOGIN"));
 235       _ANSWER(3, FAL0, FAL0);
 236
 237       if(b64_encode_buf(&b64, sbp->sb_ccred.cc_user.s, sbp->sb_ccred.cc_user.l,
 238             B64_SALLOC | B64_CRLF) == NULL)
 239          goto jleave;
 240       _OUT(b64.s);
 241       _ANSWER(3, FAL0, FAL0);
 242
 243       if(b64_encode_buf(&b64, sbp->sb_ccred.cc_pass.s, sbp->sb_ccred.cc_pass.l,
 244             B64_SALLOC | B64_CRLF) == NULL)
 245          goto jleave;
 246       _OUT(b64.s);
 247       _ANSWER(2, FAL0, FAL0);
 248       break;
 249 #ifdef HAVE_MD5
 250    case AUTHTYPE_CRAM_MD5:{
 251       char *cp;
 252
 253       _OUT(NETLINE("AUTH CRAM-MD5"));
 254       _ANSWER(3, FAL0, TRU1);
 255
 256       if((cp = cram_md5_string(&sbp->sb_ccred.cc_user, &sbp->sb_ccred.cc_pass,
 257             slp->dat)) == NULL)
 258          goto jerr_cred;
 259       _OUT(cp);
 260       _ANSWER(2, FAL0, FAL0);
 261       }break;
 262 #endif
 263 #ifdef HAVE_GSSAPI
 264    case AUTHTYPE_GSSAPI:
 265       if (n_poption & n_PO_DEBUG)
 266          n_err(_(">>> We would perform GSS-API authentication now\n"));
 267       else if (!_smtp_gssapi(sp, sbp, slp))
 268          goto jleave;
 269       break;
 270 #endif
 271    }
 272
 273 jsend:
 274    snprintf(o, sizeof o, NETLINE("MAIL FROM:<%s>"), sbp->sb_url.url_u_h.s);
 275    _OUT(o);
 276    _ANSWER(2, FAL0, FAL0);
 277
 278    for(n = sbp->sb_to; n != NULL; n = n->n_flink){
 279       if (!(n->n_type & GDEL)) { /* TODO should not happen!?! */
 280          if(n->n_flags & NAME_ADDRSPEC_WITHOUT_DOMAIN)
 281             snprintf(o, sizeof o, NETLINE("RCPT TO:<%s@%s>"),
 282                skinned_name(n), hostname);
 283          else
 284             snprintf(o, sizeof o, NETLINE("RCPT TO:<%s>"), skinned_name(n));
 285          _OUT(o);
 286          _ANSWER(2, FAL0, FAL0);
 287       }
 288    }
 289
 290    _OUT(NETLINE("DATA"));
 291    _ANSWER(3, FAL0, FAL0);
 292
 293    fflush_rewind(sbp->sb_input);
 294    cnt = fsize(sbp->sb_input);
 295    while (fgetline(&slp->buf, &slp->bufsize, &cnt, &blen, sbp->sb_input, 1)
 296          != NULL) {
 297       if (inhdr) {
 298          if (*slp->buf == '\n')
 299             inhdr = inbcc = FAL0;
 300          else if (inbcc && blankchar(*slp->buf))
 301             continue;
 302          /* We know what we have generated first, so do not look for whitespace
 303           * before the ':' */
 304          else if (!ascncasecmp(slp->buf, "bcc: ", 5)) {
 305             inbcc = TRU1;
 306             continue;
 307          } else
 308             inbcc = FAL0;
 309       }
 310
 311       if (n_poption & n_PO_DEBUG) {
 312          slp->buf[blen - 1] = '\0';
 313          n_err(">>> %s%s\n", (*slp->buf == '.' ? "." : n_empty), slp->buf);
 314          continue;
 315       }
 316       if (*slp->buf == '.')
 317          swrite1(sp, ".", 1, 1); /* TODO I/O rewrite.. */
 318       slp->buf[blen - 1] = NETNL[0];
 319       slp->buf[blen] = NETNL[1];
 320       swrite1(sp, slp->buf, blen + 1, 1);
 321    }
 322    _OUT(NETLINE("."));
 323    _ANSWER(2, FAL0, FAL0);
 324
 325    _OUT(NETLINE("QUIT"));
 326    _ANSWER(2, TRU1, FAL0);
 327    rv = TRU1;
 328 jleave:
 329    if (slp->buf != NULL)
 330       n_free(slp->buf);
 331    NYD_LEAVE;
 332    return rv;
 333 }
 334
 335 #ifdef HAVE_GSSAPI
 336 # include "smtp-gssapi.h"
 337 #endif
 338
 339 #undef _OUT
 340 #undef _ANSWER
 341
 342 FL bool_t
 343 smtp_mta(struct sendbundle *sbp)
 344 {
 345    struct sock so;
 346    sighandler_type volatile saveterm;
 347    bool_t volatile rv = FAL0;
 348    NYD_ENTER;
 349
 350    saveterm = safe_signal(SIGTERM, SIG_IGN);
 351    if (sigsetjmp(_smtp_jmp, 1))
 352       goto jleave;
 353    if (saveterm != SIG_IGN)
 354       safe_signal(SIGTERM, &_smtp_onterm);
 355
 356    if(n_poption & n_PO_DEBUG)
 357       memset(&so, 0, sizeof so);
 358    else if(!sopen(&so, &sbp->sb_url))
 359       goto jleave;
 360
 361    so.s_desc = "SMTP";
 362    rv = _smtp_talk(&so, sbp);
 363
 364    if (!(n_poption & n_PO_DEBUG))
 365       sclose(&so);
 366 jleave:
 367    safe_signal(SIGTERM, saveterm);
 368    NYD_LEAVE;
 369    return rv;
 370 }
 371 #endif /* HAVE_SMTP */
 372
 373 /* s-it-mode */