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 - 2017 Steffen (Daode) Nurpmeso <steffen@sdaoden.eu>.
   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 #undef n_FILE
  42 #define n_FILE smtp
  43
  44 #ifndef HAVE_AMALGAMATION
  45 # include "nail.h"
  46 #endif
  47
  48 EMPTY_FILE()
  49 #ifdef HAVE_SMTP
  50 #include <sys/socket.h>
  51
  52 struct smtp_line {
  53    char     *dat;    /* Actual data */
  54    size_t   datlen;
  55    char     *buf;    /* Memory buffer */
  56    size_t   bufsize;
  57 };
  58
  59 static sigjmp_buf _smtp_jmp;
  60
  61 static void    _smtp_onterm(int signo);
  62
  63 /* Get the SMTP server's answer, expecting val */
  64 static int     _smtp_read(struct sock *sp, struct smtp_line *slp, int val,
  65                   bool_t ign_eof, bool_t want_dat);
  66
  67 /* Talk to a SMTP server */
  68 static bool_t  _smtp_talk(struct sock *sp, struct sendbundle *sbp);
  69
  70 #ifdef HAVE_GSSAPI
  71 static bool_t  _smtp_gssapi(struct sock *sp, struct sendbundle *sbp,
  72                   struct smtp_line *slp);
  73 #endif
  74
  75 static void
  76 _smtp_onterm(int signo)
  77 {
  78    NYD_X; /* Signal handler */
  79    n_UNUSED(signo);
  80    siglongjmp(_smtp_jmp, 1);
  81 }
  82
  83 static int
  84 _smtp_read(struct sock *sp, struct smtp_line *slp, int val,
  85    bool_t ign_eof, bool_t want_dat)
  86 {
  87    int rv, len;
  88    char *cp;
  89    NYD_ENTER;
  90
  91    do {
  92       if ((len = sgetline(&slp->buf, &slp->bufsize, NULL, sp)) < 6) {
  93          if (len >= 0 && !ign_eof)
  94             n_err(_("Unexpected EOF on SMTP connection\n"));
  95          rv = -1;
  96          goto jleave;
  97       }
  98       if (n_poption & n_PO_VERBVERB)
  99          n_err(slp->buf);
 100       switch (slp->buf[0]) {
 101       case '1':   rv = 1; break;
 102       case '2':   rv = 2; break;
 103       case '3':   rv = 3; break;
 104       case '4':   rv = 4; break;
 105       default:    rv = 5; break;
 106       }
 107       if (val != rv)
 108          n_err(_("smtp-server: %s"), slp->buf);
 109    } while (slp->buf[3] == '-');
 110
 111    if (want_dat) {
 112       for (cp = slp->buf; digitchar(*cp); --len, ++cp)
 113          ;
 114       for (; blankchar(*cp); --len, ++cp)
 115          ;
 116       slp->dat = cp;
 117       assert(len >= 2);
 118       len -= 2;
 119       cp[slp->datlen = (size_t)len] = '\0';
 120    }
 121 jleave:
 122    NYD_LEAVE;
 123    return rv;
 124 }
 125
 126 /* Indirect SMTP I/O */
 127 #define _ANSWER(X, IGNEOF, WANTDAT) \
 128 do if (!(n_poption & n_PO_DEBUG)) {\
 129    int y;\
 130    if ((y = _smtp_read(sp, slp, X, IGNEOF, WANTDAT)) != (X) &&\
 131          (!(IGNEOF) || y != -1))\
 132       goto jleave;\
 133 } while (0)
 134 #define _OUT(X) \
 135 do {\
 136    if (n_poption & n_PO_VERBVERB)\
 137       n_err(">>> %s", X);\
 138    if (!(n_poption & n_PO_DEBUG))\
 139       swrite(sp, X);\
 140 } while (0)
 141
 142 static bool_t
 143 _smtp_talk(struct sock *sp, struct sendbundle *sbp) /* TODO n_string etc. */
 144 {
 145    char o[LINESIZE], *hostname;
 146    struct smtp_line _sl, *slp = &_sl;
 147    struct str b64;
 148    struct name *n;
 149    size_t blen, cnt;
 150    bool_t inhdr = TRU1, inbcc = FAL0, rv = FAL0;
 151    NYD_ENTER;
 152
 153    hostname = n_nodename(TRU1);
 154    slp->buf = NULL;
 155    slp->bufsize = 0;
 156
 157    /* Read greeting */
 158    _ANSWER(2, FAL0, FAL0);
 159
 160 #ifdef HAVE_SSL
 161    if (!sp->s_use_ssl && xok_blook(smtp_use_starttls, &sbp->sb_url, OXM_ALL)) {
 162       snprintf(o, sizeof o, NETLINE("EHLO %s"), hostname);
 163       _OUT(o);
 164       _ANSWER(2, FAL0, FAL0);
 165
 166       _OUT(NETLINE("STARTTLS"));
 167       _ANSWER(2, FAL0, FAL0);
 168
 169       if (!(n_poption & n_PO_DEBUG) && ssl_open(&sbp->sb_url, sp) != OKAY)
 170          goto jleave;
 171    }
 172 #else
 173    if (xok_blook(smtp_use_starttls, &sbp->sb_url, OXM_ALL)) {
 174       n_err(_("No SSL support compiled in\n"));
 175       goto jleave;
 176    }
 177 #endif
 178
 179    /* Shorthand: no authentication, plain HELO? */
 180    if (sbp->sb_ccred.cc_authtype == AUTHTYPE_NONE) {
 181       snprintf(o, sizeof o, NETLINE("HELO %s"), hostname);
 182       _OUT(o);
 183       _ANSWER(2, FAL0, FAL0);
 184       goto jsend;
 185    }
 186
 187    /* We'll have to deal with authentication */
 188    snprintf(o, sizeof o, NETLINE("EHLO %s"), hostname);
 189    _OUT(o);
 190    _ANSWER(2, FAL0, FAL0);
 191
 192    switch (sbp->sb_ccred.cc_authtype) {
 193    default:
 194       /* FALLTHRU (doesn't happen) */
 195    case AUTHTYPE_PLAIN:
 196       cnt = sbp->sb_ccred.cc_user.l;
 197       if(sbp->sb_ccred.cc_pass.l >= UIZ_MAX - 2 ||
 198             cnt >= UIZ_MAX - 2 - sbp->sb_ccred.cc_pass.l){
 199 jerr_cred:
 200          n_err(_("Credentials overflow buffer sizes\n"));
 201          goto jleave;
 202       }
 203       cnt += sbp->sb_ccred.cc_pass.l;
 204
 205       if(cnt >= sizeof(o) - 2)
 206          goto jerr_cred;
 207       cnt += 2;
 208       if(b64_encode_calc_size(cnt) == UIZ_MAX)
 209          goto jerr_cred;
 210
 211       _OUT(NETLINE("AUTH PLAIN"));
 212       _ANSWER(3, FAL0, FAL0);
 213
 214       snprintf(o, sizeof o, "%c%s%c%s",
 215          '\0', sbp->sb_ccred.cc_user.s, '\0', sbp->sb_ccred.cc_pass.s);
 216       if(b64_encode_buf(&b64, o, cnt, B64_SALLOC | B64_CRLF) == NULL)
 217          goto jleave;
 218       _OUT(b64.s);
 219       _ANSWER(2, FAL0, FAL0);
 220       break;
 221    case AUTHTYPE_LOGIN:
 222       if(b64_encode_calc_size(sbp->sb_ccred.cc_user.l) == UIZ_MAX ||
 223             b64_encode_calc_size(sbp->sb_ccred.cc_pass.l) == UIZ_MAX)
 224          goto jerr_cred;
 225
 226       _OUT(NETLINE("AUTH LOGIN"));
 227       _ANSWER(3, FAL0, FAL0);
 228
 229       if(b64_encode_buf(&b64, sbp->sb_ccred.cc_user.s, sbp->sb_ccred.cc_user.l,
 230             B64_SALLOC | B64_CRLF) == NULL)
 231          goto jleave;
 232       _OUT(b64.s);
 233       _ANSWER(3, FAL0, FAL0);
 234
 235       if(b64_encode_buf(&b64, sbp->sb_ccred.cc_pass.s, sbp->sb_ccred.cc_pass.l,
 236             B64_SALLOC | B64_CRLF) == NULL)
 237          goto jleave;
 238       _OUT(b64.s);
 239       _ANSWER(2, FAL0, FAL0);
 240       break;
 241 #ifdef HAVE_MD5
 242    case AUTHTYPE_CRAM_MD5:{
 243       char *cp;
 244
 245       _OUT(NETLINE("AUTH CRAM-MD5"));
 246       _ANSWER(3, FAL0, TRU1);
 247
 248       if((cp = cram_md5_string(&sbp->sb_ccred.cc_user, &sbp->sb_ccred.cc_pass,
 249             slp->dat)) == NULL)
 250          goto jerr_cred;
 251       _OUT(cp);
 252       _ANSWER(2, FAL0, FAL0);
 253    }  break;
 254 #endif
 255 #ifdef HAVE_GSSAPI
 256    case AUTHTYPE_GSSAPI:
 257       if (n_poption & n_PO_DEBUG)
 258          n_err(_(">>> We would perform GSS-API authentication now\n"));
 259       else if (!_smtp_gssapi(sp, sbp, slp))
 260          goto jleave;
 261       break;
 262 #endif
 263    }
 264
 265 jsend:
 266    snprintf(o, sizeof o, NETLINE("MAIL FROM:<%s>"), sbp->sb_url.url_u_h.s);
 267    _OUT(o);
 268    _ANSWER(2, FAL0, FAL0);
 269
 270    for (n = sbp->sb_to; n != NULL; n = n->n_flink) {
 271       if (!(n->n_type & GDEL)) {
 272          snprintf(o, sizeof o, NETLINE("RCPT TO:<%s>"), skinned_name(n));
 273          _OUT(o);
 274          _ANSWER(2, FAL0, FAL0);
 275       }
 276    }
 277
 278    _OUT(NETLINE("DATA"));
 279    _ANSWER(3, FAL0, FAL0);
 280
 281    fflush_rewind(sbp->sb_input);
 282    cnt = fsize(sbp->sb_input);
 283    while (fgetline(&slp->buf, &slp->bufsize, &cnt, &blen, sbp->sb_input, 1)
 284          != NULL) {
 285       if (inhdr) {
 286          if (*slp->buf == '\n')
 287             inhdr = inbcc = FAL0;
 288          else if (inbcc && blankchar(*slp->buf))
 289             continue;
 290          /* We know what we have generated first, so do not look for whitespace
 291           * before the ':' */
 292          else if (!ascncasecmp(slp->buf, "bcc: ", 5)) {
 293             inbcc = TRU1;
 294             continue;
 295          } else
 296             inbcc = FAL0;
 297       }
 298
 299       if (n_poption & n_PO_DEBUG) {
 300          slp->buf[blen - 1] = '\0';
 301          n_err(">>> %s%s\n", (*slp->buf == '.' ? "." : n_empty), slp->buf);
 302          continue;
 303       }
 304       if (*slp->buf == '.')
 305          swrite1(sp, ".", 1, 1); /* TODO I/O rewrite.. */
 306       slp->buf[blen - 1] = NETNL[0];
 307       slp->buf[blen] = NETNL[1];
 308       swrite1(sp, slp->buf, blen + 1, 1);
 309    }
 310    _OUT(NETLINE("."));
 311    _ANSWER(2, FAL0, FAL0);
 312
 313    _OUT(NETLINE("QUIT"));
 314    _ANSWER(2, TRU1, FAL0);
 315    rv = TRU1;
 316 jleave:
 317    if (slp->buf != NULL)
 318       free(slp->buf);
 319    NYD_LEAVE;
 320    return rv;
 321 }
 322
 323 #ifdef HAVE_GSSAPI
 324 # include "smtp-gssapi.h"
 325 #endif
 326
 327 #undef _OUT
 328 #undef _ANSWER
 329
 330 FL bool_t
 331 smtp_mta(struct sendbundle *sbp)
 332 {
 333    struct sock so;
 334    sighandler_type volatile saveterm;
 335    bool_t volatile rv = FAL0;
 336    NYD_ENTER;
 337
 338    saveterm = safe_signal(SIGTERM, SIG_IGN);
 339    if (sigsetjmp(_smtp_jmp, 1))
 340       goto jleave;
 341    if (saveterm != SIG_IGN)
 342       safe_signal(SIGTERM, &_smtp_onterm);
 343
 344    memset(&so, 0, sizeof so);
 345    if (!(n_poption & n_PO_DEBUG) && !sopen(&so, &sbp->sb_url))
 346       goto jleave;
 347
 348    so.s_desc = "SMTP";
 349    rv = _smtp_talk(&so, sbp);
 350
 351    if (!(n_poption & n_PO_DEBUG))
 352       sclose(&so);
 353 jleave:
 354    safe_signal(SIGTERM, saveterm);
 355    NYD_LEAVE;
 356    return rv;
 357 }
 358 #endif /* HAVE_SMTP */
 359
 360 /* s-it-mode */