net.c

   1 /*
   2  * Copyright (c) 2008 The DragonFly Project.  All rights reserved.
   3  *
   4  * This code is derived from software contributed to The DragonFly Project
   5  * by Matthias Schmidt <matthias@dragonflybsd.org>, University of Marburg,
   6  * Germany.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  *
  12  * 1. Redistributions of source code must retain the above copyright
  13  *    notice, this list of conditions and the following disclaimer.
  14  * 2. Redistributions in binary form must reproduce the above copyright
  15  *    notice, this list of conditions and the following disclaimer in
  16  *    the documentation and/or other materials provided with the
  17  *    distribution.
  18  * 3. Neither the name of The DragonFly Project nor the names of its
  19  *    contributors may be used to endorse or promote products derived
  20  *    from this software without specific, prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  23  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  24  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  25  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
  26  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  27  * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
  28  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  29  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
  30  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  31  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  32  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  33  * SUCH DAMAGE.
  34  */
  35
  36 #include <sys/param.h>
  37 #include <sys/queue.h>
  38 #include <sys/stat.h>
  39 #include <sys/types.h>
  40 #include <sys/socket.h>
  41 #include <netinet/in.h>
  42 #include <arpa/inet.h>
  43
  44 #include <openssl/ssl.h>
  45 #include <openssl/err.h>
  46
  47 #include <err.h>
  48 #include <errno.h>
  49 #include <netdb.h>
  50 #include <setjmp.h>
  51 #include <signal.h>
  52 #include <syslog.h>
  53 #include <unistd.h>
  54
  55 #include "dma.h"
  56
  57 static jmp_buf timeout_alarm;
  58 char neterr[BUF_SIZE];
  59
  60 char *
  61 ssl_errstr(void)
  62 {
  63         long oerr, nerr;
  64
  65         oerr = 0;
  66         while ((nerr = ERR_get_error()) != 0)
  67                 oerr = nerr;
  68
  69         return (ERR_error_string(oerr, NULL));
  70 }
  71
  72 static void
  73 sig_alarm(int signo __unused)
  74 {
  75         longjmp(timeout_alarm, 1);
  76 }
  77
  78 ssize_t
  79 send_remote_command(int fd, const char* fmt, ...)
  80 {
  81         va_list va;
  82         char cmd[4096];
  83         size_t len, pos;
  84         int s;
  85         ssize_t n;
  86
  87         va_start(va, fmt);
  88         s = vsnprintf(cmd, sizeof(cmd) - 2, fmt, va);
  89         va_end(va);
  90         if (s == sizeof(cmd) - 2 || s < 0) {
  91                 strcpy(neterr, "Internal error: oversized command string");
  92                 return (-1);
  93         }
  94
  95         /* We *know* there are at least two more bytes available */
  96         strcat(cmd, "\r\n");
  97         len = strlen(cmd);
  98
  99         if (((config->features & SECURETRANS) != 0) &&
 100             ((config->features & NOSSL) == 0)) {
 101                 while ((s = SSL_write(config->ssl, (const char*)cmd, len)) <= 0) {
 102                         s = SSL_get_error(config->ssl, s);
 103                         if (s != SSL_ERROR_WANT_READ &&
 104                             s != SSL_ERROR_WANT_WRITE) {
 105                                 strncpy(neterr, ssl_errstr(), sizeof(neterr));
 106                                 return (-1);
 107                         }
 108                 }
 109         }
 110         else {
 111                 pos = 0;
 112                 while (pos < len) {
 113                         n = write(fd, cmd + pos, len - pos);
 114                         if (n < 0)
 115                                 return (-1);
 116                         pos += n;
 117                 }
 118         }
 119
 120         return (len);
 121 }
 122
 123 int
 124 read_remote(int fd, int extbufsize, char *extbuf)
 125 {
 126         ssize_t rlen = 0;
 127         size_t pos, len;
 128         char buff[BUF_SIZE];
 129         int done = 0, status = 0, extbufpos = 0;
 130
 131         if (signal(SIGALRM, sig_alarm) == SIG_ERR) {
 132                 snprintf(neterr, sizeof(neterr), "SIGALRM error: %s",
 133                     strerror(errno));
 134                 return (-1);
 135         }
 136         if (setjmp(timeout_alarm) != 0) {
 137                 snprintf(neterr, sizeof(neterr), "Timeout reached");
 138                 return (-1);
 139         }
 140         alarm(CON_TIMEOUT);
 141
 142         /*
 143          * Remote reading code from femail.c written by Henning Brauer of
 144          * OpenBSD and released under a BSD style license.
 145          */
 146         for (len = pos = 0; !done; ) {
 147                 rlen = 0;
 148                 if (pos == 0 ||
 149                     (pos > 0 && memchr(buff + pos, '\n', len - pos) == NULL)) {
 150                         memmove(buff, buff + pos, len - pos);
 151                         len -= pos;
 152                         pos = 0;
 153                         if (((config->features & SECURETRANS) != 0) &&
 154                             (config->features & NOSSL) == 0) {
 155                                 if ((rlen = SSL_read(config->ssl, buff + len,
 156                                     sizeof(buff) - len)) == -1) {
 157                                         strncpy(neterr, ssl_errstr(), sizeof(neterr));
 158                                         return (-1);
 159                                 }
 160                         } else {
 161                                 if ((rlen = read(fd, buff + len, sizeof(buff) - len)) == -1) {
 162                                         strncpy(neterr, strerror(errno), sizeof(neterr));
 163                                         return (-1);
 164                                 }
 165                         }
 166                         len += rlen;
 167                 }
 168                 /*
 169                  * If there is an external buffer with a size bigger than zero
 170                  * and as long as there is space in the external buffer and
 171                  * there are new characters read from the mailserver
 172                  * copy them to the external buffer
 173                  */
 174                 if (extbufpos <= (extbufsize - 1) && rlen && extbufsize > 0
 175                     && extbuf != NULL) {
 176                         /* do not write over the bounds of the buffer */
 177                         if(extbufpos + rlen > (extbufsize - 1)) {
 178                                 rlen = extbufsize - extbufpos;
 179                         }
 180                         memcpy(extbuf + extbufpos, buff + len - rlen, rlen);
 181                         extbufpos += rlen;
 182                 }
 183                 for (; pos < len && buff[pos] >= '0' && buff[pos] <= '9'; pos++)
 184                         ; /* Do nothing */
 185
 186                 if (pos == len)
 187                         return (0);
 188
 189                 if (buff[pos] == ' ') {
 190                         done = 1;
 191                 } else if (buff[pos] != '-') {
 192                         strcpy(neterr, "invalid syntax in reply from server");
 193                         return (-1);
 194                 }
 195
 196                 /* skip up to \n */
 197                 for (; pos < len && buff[pos - 1] != '\n'; pos++)
 198                         ; /* Do nothing */
 199
 200         }
 201         alarm(0);
 202
 203         buff[len] = '\0';
 204         while (len > 0 && (buff[len - 1] == '\r' || buff[len - 1] == '\n'))
 205                 buff[--len] = '\0';
 206         snprintf(neterr, sizeof(neterr), "%s", buff);
 207         status = atoi(buff);
 208         return (status/100);
 209 }
 210
 211 /*
 212  * Handle SMTP authentication
 213  */
 214 static int
 215 smtp_login(int fd, char *login, char* password)
 216 {
 217         char *temp;
 218         int len, res = 0;
 219
 220         res = smtp_auth_md5(fd, login, password);
 221         if (res == 0) {
 222                 return (0);
 223         } else if (res == -2) {
 224         /*
 225          * If the return code is -2, then then the login attempt failed,
 226          * do not try other login mechanisms
 227          */
 228                 return (1);
 229         }
 230
 231         if ((config->features & INSECURE) != 0 ||
 232             (config->features & SECURETRANS) != 0) {
 233                 /* Send AUTH command according to RFC 2554 */
 234                 send_remote_command(fd, "AUTH LOGIN");
 235                 if (read_remote(fd, 0, NULL) != 3) {
 236                         syslog(LOG_NOTICE, "remote delivery deferred:"
 237                                         " AUTH login not available: %s",
 238                                         neterr);
 239                         return (1);
 240                 }
 241
 242                 len = base64_encode(login, strlen(login), &temp);
 243                 if (len < 0) {
 244 encerr:
 245                         syslog(LOG_ERR, "can not encode auth reply: %m");
 246                         return (1);
 247                 }
 248
 249                 send_remote_command(fd, "%s", temp);
 250                 free(temp);
 251                 res = read_remote(fd, 0, NULL);
 252                 if (res != 3) {
 253                         syslog(LOG_NOTICE, "remote delivery %s: AUTH login failed: %s",
 254                                res == 5 ? "failed" : "deferred", neterr);
 255                         return (res == 5 ? -1 : 1);
 256                 }
 257
 258                 len = base64_encode(password, strlen(password), &temp);
 259                 if (len < 0)
 260                         goto encerr;
 261
 262                 send_remote_command(fd, "%s", temp);
 263                 free(temp);
 264                 res = read_remote(fd, 0, NULL);
 265                 if (res != 2) {
 266                         syslog(LOG_NOTICE, "remote delivery %s: Authentication failed: %s",
 267                                         res == 5 ? "failed" : "deferred", neterr);
 268                         return (res == 5 ? -1 : 1);
 269                 }
 270         } else {
 271                 syslog(LOG_WARNING, "non-encrypted SMTP login is disabled in config, so skipping it. ");
 272                 return (1);
 273         }
 274
 275         return (0);
 276 }
 277
 278 static int
 279 open_connection(const char *host)
 280 {
 281         struct addrinfo hints, *res, *res0;
 282         char servname[128];
 283         const char *errmsg = NULL;
 284         int fd, error = 0, port;
 285
 286         if (config->port != 0)
 287                 port = config->port;
 288         else
 289                 port = SMTP_PORT;
 290
 291         /* XXX FIXME get MX record of host */
 292         /* Shamelessly taken from getaddrinfo(3) */
 293         memset(&hints, 0, sizeof(hints));
 294         hints.ai_family = PF_UNSPEC;
 295         hints.ai_socktype = SOCK_STREAM;
 296         hints.ai_protocol = IPPROTO_TCP;
 297
 298         snprintf(servname, sizeof(servname), "%d", port);
 299         error = getaddrinfo(host, servname, &hints, &res0);
 300         if (error) {
 301                 syslog(LOG_NOTICE, "remote delivery deferred: %s", gai_strerror(error));
 302                 return (-1);
 303         }
 304         fd = -1;
 305         for (res = res0; res; res = res->ai_next) {
 306                 fd=socket(res->ai_family, res->ai_socktype, res->ai_protocol);
 307                 if (fd < 0) {
 308                         errmsg = "socket failed";
 309                         continue;
 310                 }
 311                 if (connect(fd, res->ai_addr, res->ai_addrlen) < 0) {
 312                         errmsg = "connect failed";
 313                         close(fd);
 314                         fd = -1;
 315                         continue;
 316                 }
 317                 break;
 318         }
 319         if (fd < 0) {
 320                 syslog(LOG_NOTICE, "remote delivery deferred: %s (%s:%s)",
 321                         errmsg, host, servname);
 322                 freeaddrinfo(res0);
 323                 return (-1);
 324         }
 325         freeaddrinfo(res0);
 326         return (fd);
 327 }
 328
 329 static void
 330 close_connection(int fd)
 331 {
 332         if (((config->features & SECURETRANS) != 0) &&
 333             ((config->features & NOSSL) == 0))
 334                 SSL_shutdown(config->ssl);
 335
 336         if (config->ssl != NULL)
 337                 SSL_free(config->ssl);
 338
 339         close(fd);
 340 }
 341
 342 int
 343 deliver_remote(struct qitem *it, const char **errmsg)
 344 {
 345         struct authuser *a;
 346         char *host, line[1000];
 347         int fd, error = 0, do_auth = 0, res = 0;
 348         size_t linelen;
 349         /* asprintf can't take const */
 350         void *errmsgc = __DECONST(char **, errmsg);
 351
 352         if (fseek(it->mailf, it->hdrlen, SEEK_SET) != 0) {
 353                 asprintf(errmsgc, "can not seek: %s", strerror(errno));
 354                 return (-1);
 355         }
 356
 357         host = strrchr(it->addr, '@');
 358         /* Should not happen */
 359         if (host == NULL) {
 360                 asprintf(errmsgc, "Internal error: badly formed address %s",
 361                     it->addr);
 362                 return(-1);
 363         } else {
 364                 /* Step over the @ */
 365                 host++;
 366         }
 367
 368         /* Smarthost support? */
 369         if (config->smarthost != NULL && strlen(config->smarthost) > 0) {
 370                 syslog(LOG_INFO, "using smarthost (%s:%i)",
 371                        config->smarthost, config->port);
 372                 host = config->smarthost;
 373         }
 374
 375         fd = open_connection(host);
 376         if (fd < 0)
 377                 return (1);
 378
 379         /* Check first reply from remote host */
 380         config->features |= NOSSL;
 381         res = read_remote(fd, 0, NULL);
 382         if (res != 2) {
 383                 syslog(LOG_WARNING, "Invalid initial response: %i", res);
 384                 return(1);
 385         }
 386         config->features &= ~NOSSL;
 387
 388         if ((config->features & SECURETRANS) != 0) {
 389                 error = smtp_init_crypto(fd, config->features);
 390                 if (error >= 0)
 391                         syslog(LOG_DEBUG, "SSL initialization successful");
 392                 else
 393                         goto out;
 394         }
 395
 396         /* XXX allow HELO fallback */
 397         /* XXX record ESMTP keywords */
 398         send_remote_command(fd, "EHLO %s", hostname());
 399         if (read_remote(fd, 0, NULL) != 2) {
 400                 syslog(LOG_WARNING, "remote delivery deferred: EHLO failed: %s", neterr);
 401                 asprintf(errmsgc, "%s did not like our EHLO:\n%s",
 402                     host, neterr);
 403                 return (-1);
 404         }
 405
 406         /*
 407          * Use SMTP authentication if the user defined an entry for the remote
 408          * or smarthost
 409          */
 410         SLIST_FOREACH(a, &authusers, next) {
 411                 if (strcmp(a->host, host) == 0) {
 412                         do_auth = 1;
 413                         break;
 414                 }
 415         }
 416
 417         if (do_auth == 1) {
 418                 /*
 419                  * Check if the user wants plain text login without using
 420                  * encryption.
 421                  */
 422                 syslog(LOG_INFO, "using SMTP authentication");
 423                 error = smtp_login(fd, a->login, a->password);
 424                 if (error < 0) {
 425                         syslog(LOG_ERR, "remote delivery failed:"
 426                                         " SMTP login failed: %m");
 427                         asprintf(errmsgc, "SMTP login to %s failed", host);
 428                         return (-1);
 429                 }
 430                 /* SMTP login is not available, so try without */
 431                 else if (error > 0) {
 432                         syslog(LOG_WARNING, "SMTP login not available. Trying without.");
 433                 }
 434         }
 435
 436 #define READ_REMOTE_CHECK(c, exp)       \
 437         res = read_remote(fd, 0, NULL); \
 438         if (res == 5) { \
 439                 syslog(LOG_ERR, "remote delivery failed: " \
 440                        c " failed: %s", neterr); \
 441                 asprintf(errmsgc, "%s did not like our " c ":\n%s", \
 442                     host, neterr); \
 443                 return (-1); \
 444         } else if (res != exp) { \
 445                 syslog(LOG_NOTICE, "remote delivery deferred: " \
 446                        c " failed: %s", neterr); \
 447                 return (1); \
 448         }
 449
 450         /* XXX send ESMTP ENVID, RET (FULL/HDRS) and 8BITMIME */
 451         send_remote_command(fd, "MAIL FROM:<%s>", it->sender);
 452         READ_REMOTE_CHECK("MAIL FROM", 2);
 453
 454         /* XXX send ESMTP ORCPT */
 455         send_remote_command(fd, "RCPT TO:<%s>", it->addr);
 456         READ_REMOTE_CHECK("RCPT TO", 2);
 457
 458         send_remote_command(fd, "DATA");
 459         READ_REMOTE_CHECK("DATA", 3);
 460
 461         error = 0;
 462         while (!feof(it->mailf)) {
 463                 if (fgets(line, sizeof(line), it->mailf) == NULL)
 464                         break;
 465                 linelen = strlen(line);
 466                 if (linelen == 0 || line[linelen - 1] != '\n') {
 467                         syslog(LOG_CRIT, "remote delivery failed: corrupted queue file");
 468                         *errmsg = "corrupted queue file";
 469                         error = -1;
 470                         goto out;
 471                 }
 472
 473                 /* Remove trailing \n's and escape leading dots */
 474                 trim_line(line);
 475
 476                 /*
 477                  * If the first character is a dot, we escape it so the line
 478                  * length increases
 479                 */
 480                 if (line[0] == '.')
 481                         linelen++;
 482
 483                 if (send_remote_command(fd, "%s", line) != (ssize_t)linelen+1) {
 484                         syslog(LOG_NOTICE, "remote delivery deferred: write error");
 485                         error = 1;
 486                         goto out;
 487                 }
 488         }
 489
 490         send_remote_command(fd, ".");
 491         READ_REMOTE_CHECK("final DATA", 2);
 492
 493         send_remote_command(fd, "QUIT");
 494         if (read_remote(fd, 0, NULL) != 2)
 495                 syslog(LOG_INFO, "remote delivery succeeded but QUIT failed: %s", neterr);
 496 out:
 497
 498         close_connection(fd);
 499         return (error);
 500 }
 501