src/src/smtp_out.c

   1 /*************************************************
   2 *     Exim - an Internet mail transport agent    *
   3 *************************************************/
   4
   5 /* Copyright (c) University of Cambridge 1995 - 2018 */
   6 /* See the file NOTICE for conditions of use and distribution. */
   7
   8 /* A number of functions for driving outgoing SMTP calls. */
   9
  10
  11 #include "exim.h"
  12 #include "transports/smtp.h"
  13
  14
  15
  16 /*************************************************
  17 *           Find an outgoing interface           *
  18 *************************************************/
  19
  20 /* This function is called from the smtp transport and also from the callout
  21 code in verify.c. Its job is to expand a string to get a list of interfaces,
  22 and choose a suitable one (IPv4 or IPv6) for the outgoing address.
  23
  24 Arguments:
  25   istring    string interface setting, may be NULL, meaning "any", in
  26                which case the function does nothing
  27   host_af    AF_INET or AF_INET6 for the outgoing IP address
  28   addr       the mail address being handled (for setting errors)
  29   interface  point this to the interface
  30   msg        to add to any error message
  31
  32 Returns:     TRUE on success, FALSE on failure, with error message
  33                set in addr and transport_return set to PANIC
  34 */
  35
  36 BOOL
  37 smtp_get_interface(uschar *istring, int host_af, address_item *addr,
  38   uschar **interface, uschar *msg)
  39 {
  40 const uschar * expint;
  41 uschar *iface;
  42 int sep = 0;
  43
  44 if (!istring) return TRUE;
  45
  46 if (!(expint = expand_string(istring)))
  47   {
  48   if (f.expand_string_forcedfail) return TRUE;
  49   addr->transport_return = PANIC;
  50   addr->message = string_sprintf("failed to expand \"interface\" "
  51       "option for %s: %s", msg, expand_string_message);
  52   return FALSE;
  53   }
  54
  55 while (isspace(*expint)) expint++;
  56 if (*expint == 0) return TRUE;
  57
  58 while ((iface = string_nextinlist(&expint, &sep, big_buffer,
  59           big_buffer_size)))
  60   {
  61   if (string_is_ip_address(iface, NULL) == 0)
  62     {
  63     addr->transport_return = PANIC;
  64     addr->message = string_sprintf("\"%s\" is not a valid IP "
  65       "address for the \"interface\" option for %s",
  66       iface, msg);
  67     return FALSE;
  68     }
  69
  70   if (((Ustrchr(iface, ':') == NULL)? AF_INET:AF_INET6) == host_af)
  71     break;
  72   }
  73
  74 if (iface) *interface = string_copy(iface);
  75 return TRUE;
  76 }
  77
  78
  79
  80 /*************************************************
  81 *           Find an outgoing port                *
  82 *************************************************/
  83
  84 /* This function is called from the smtp transport and also from the callout
  85 code in verify.c. Its job is to find a port number. Note that getservbyname()
  86 produces the number in network byte order.
  87
  88 Arguments:
  89   rstring     raw (unexpanded) string representation of the port
  90   addr        the mail address being handled (for setting errors)
  91   port        stick the port in here
  92   msg         for adding to error message
  93
  94 Returns:      TRUE on success, FALSE on failure, with error message set
  95                 in addr, and transport_return set to PANIC
  96 */
  97
  98 BOOL
  99 smtp_get_port(uschar *rstring, address_item *addr, int *port, uschar *msg)
 100 {
 101 uschar *pstring = expand_string(rstring);
 102
 103 if (!pstring)
 104   {
 105   addr->transport_return = PANIC;
 106   addr->message = string_sprintf("failed to expand \"%s\" (\"port\" option) "
 107     "for %s: %s", rstring, msg, expand_string_message);
 108   return FALSE;
 109   }
 110
 111 if (isdigit(*pstring))
 112   {
 113   uschar *end;
 114   *port = Ustrtol(pstring, &end, 0);
 115   if (end != pstring + Ustrlen(pstring))
 116     {
 117     addr->transport_return = PANIC;
 118     addr->message = string_sprintf("invalid port number for %s: %s", msg,
 119       pstring);
 120     return FALSE;
 121     }
 122   }
 123
 124 else
 125   {
 126   struct servent *smtp_service = getservbyname(CS pstring, "tcp");
 127   if (!smtp_service)
 128     {
 129     addr->transport_return = PANIC;
 130     addr->message = string_sprintf("TCP port \"%s\" is not defined for %s",
 131       pstring, msg);
 132     return FALSE;
 133     }
 134   *port = ntohs(smtp_service->s_port);
 135   }
 136
 137 return TRUE;
 138 }
 139
 140
 141
 142
 143 #ifdef TCP_FASTOPEN
 144 static void
 145 tfo_out_check(int sock)
 146 {
 147 # if defined(TCP_INFO) && defined(EXIM_HAVE_TCPI_UNACKED)
 148 struct tcp_info tinfo;
 149 socklen_t len = sizeof(tinfo);
 150
 151 if (getsockopt(sock, IPPROTO_TCP, TCP_INFO, &tinfo, &len) == 0)
 152   {
 153   switch (tcp_out_fastopen)
 154     {
 155       /* This is a somewhat dubious detection method; totally undocumented so likely
 156       to fail in future kernels.  There seems to be no documented way.  What we really
 157       want to know is if the server sent smtp-banner data before our ACK of his SYN,ACK
 158       hit him.  What this (possibly?) detects is whether we sent a TFO cookie with our
 159       SYN, as distinct from a TFO request.  This gets a false-positive when the server
 160       key is rotated; we send the old one (which this test sees) but the server returns
 161       the new one and does not send its SMTP banner before we ACK his SYN,ACK.
 162        To force that rotation case:
 163        '# echo -n "00000000-00000000-00000000-0000000" >/proc/sys/net/ipv4/tcp_fastopen_key'
 164       The kernel seems to be counting unack'd packets. */
 165
 166     case 1:
 167       if (tinfo.tcpi_unacked > 1)
 168         {
 169         DEBUG(D_transport|D_v)
 170           debug_printf("TCP_FASTOPEN tcpi_unacked %d\n", tinfo.tcpi_unacked);
 171         tcp_out_fastopen = 2;
 172         }
 173       break;
 174
 175 #ifdef notdef           /* This seems to always fire, meaning that we cannot tell
 176                         whether the server accepted data we sent.  For now assume
 177                         that it did. */
 178
 179       /* If there was data-on-SYN but we had to retrasnmit it, declare no TFO */
 180
 181     case 2:
 182       if (!(tinfo.tcpi_options & TCPI_OPT_SYN_DATA))
 183         {
 184         DEBUG(D_transport|D_v) debug_printf("TFO: had to retransmit\n");
 185         tcp_out_fastopen = 0;
 186         }
 187       break;
 188 #endif
 189     }
 190
 191   }
 192 # endif
 193 }
 194 #endif
 195
 196
 197 /* Arguments as for smtp_connect(), plus
 198   early_data    if non-NULL, data to be sent - preferably in the TCP SYN segment
 199
 200 Returns:      connected socket number, or -1 with errno set
 201 */
 202
 203 int
 204 smtp_sock_connect(host_item * host, int host_af, int port, uschar * interface,
 205   transport_instance * tb, int timeout, const blob * early_data)
 206 {
 207 smtp_transport_options_block * ob =
 208   (smtp_transport_options_block *)tb->options_block;
 209 const uschar * dscp = ob->dscp;
 210 int dscp_value;
 211 int dscp_level;
 212 int dscp_option;
 213 int sock;
 214 int save_errno = 0;
 215 const blob * fastopen_blob = NULL;
 216
 217
 218 #ifndef DISABLE_EVENT
 219 deliver_host_address = host->address;
 220 deliver_host_port = port;
 221 if (event_raise(tb->event_action, US"tcp:connect", NULL)) return -1;
 222 #endif
 223
 224 if ((sock = ip_socket(SOCK_STREAM, host_af)) < 0) return -1;
 225
 226 /* Set TCP_NODELAY; Exim does its own buffering. */
 227
 228 if (setsockopt(sock, IPPROTO_TCP, TCP_NODELAY, US &on, sizeof(on)))
 229   HDEBUG(D_transport|D_acl|D_v)
 230     debug_printf_indent("failed to set NODELAY: %s ", strerror(errno));
 231
 232 /* Set DSCP value, if we can. For now, if we fail to set the value, we don't
 233 bomb out, just log it and continue in default traffic class. */
 234
 235 if (dscp && dscp_lookup(dscp, host_af, &dscp_level, &dscp_option, &dscp_value))
 236   {
 237   HDEBUG(D_transport|D_acl|D_v)
 238     debug_printf_indent("DSCP \"%s\"=%x ", dscp, dscp_value);
 239   if (setsockopt(sock, dscp_level, dscp_option, &dscp_value, sizeof(dscp_value)) < 0)
 240     HDEBUG(D_transport|D_acl|D_v)
 241       debug_printf_indent("failed to set DSCP: %s ", strerror(errno));
 242   /* If the kernel supports IPv4 and IPv6 on an IPv6 socket, we need to set the
 243   option for both; ignore failures here */
 244   if (host_af == AF_INET6 &&
 245       dscp_lookup(dscp, AF_INET, &dscp_level, &dscp_option, &dscp_value))
 246     (void) setsockopt(sock, dscp_level, dscp_option, &dscp_value, sizeof(dscp_value));
 247   }
 248
 249 /* Bind to a specific interface if requested. Caller must ensure the interface
 250 is the same type (IPv4 or IPv6) as the outgoing address. */
 251
 252 if (interface && ip_bind(sock, host_af, interface, 0) < 0)
 253   {
 254   save_errno = errno;
 255   HDEBUG(D_transport|D_acl|D_v)
 256     debug_printf_indent("unable to bind outgoing SMTP call to %s: %s", interface,
 257     strerror(errno));
 258   }
 259
 260 /* Connect to the remote host, and add keepalive to the socket before returning
 261 it, if requested.  If the build supports TFO, request it - and if the caller
 262 requested some early-data then include that in the TFO request. */
 263
 264 else
 265   {
 266 #ifdef TCP_FASTOPEN
 267   if (verify_check_given_host(&ob->hosts_try_fastopen, host) == OK)
 268     fastopen_blob = early_data ? early_data : &tcp_fastopen_nodata;
 269 #endif
 270
 271   if (ip_connect(sock, host_af, host->address, port, timeout, fastopen_blob) < 0)
 272     save_errno = errno;
 273   else if (early_data && !fastopen_blob && early_data->data && early_data->len)
 274     if (send(sock, early_data->data, early_data->len, 0) < 0)
 275       save_errno = errno;
 276   }
 277
 278 /* Either bind() or connect() failed */
 279
 280 if (save_errno != 0)
 281   {
 282   HDEBUG(D_transport|D_acl|D_v)
 283     {
 284     debug_printf_indent("failed: %s", CUstrerror(save_errno));
 285     if (save_errno == ETIMEDOUT)
 286       debug_printf(" (timeout=%s)", readconf_printtime(timeout));
 287     debug_printf("\n");
 288     }
 289   (void)close(sock);
 290   errno = save_errno;
 291   return -1;
 292   }
 293
 294 /* Both bind() and connect() succeeded */
 295
 296 else
 297   {
 298   union sockaddr_46 interface_sock;
 299   EXIM_SOCKLEN_T size = sizeof(interface_sock);
 300   HDEBUG(D_transport|D_acl|D_v) debug_printf_indent("connected\n");
 301   if (getsockname(sock, (struct sockaddr *)(&interface_sock), &size) == 0)
 302     sending_ip_address = host_ntoa(-1, &interface_sock, NULL, &sending_port);
 303   else
 304     {
 305     log_write(0, LOG_MAIN | ((errno == ECONNRESET)? 0 : LOG_PANIC),
 306       "getsockname() failed: %s", strerror(errno));
 307     close(sock);
 308     return -1;
 309     }
 310   if (ob->keepalive) ip_keepalive(sock, host->address, TRUE);
 311 #ifdef TCP_FASTOPEN
 312   if (fastopen_blob) tfo_out_check(sock);
 313 #endif
 314   return sock;
 315   }
 316 }
 317
 318
 319
 320
 321
 322 void
 323 smtp_port_for_connect(host_item * host, int port)
 324 {
 325 if (host->port != PORT_NONE)
 326   {
 327   HDEBUG(D_transport|D_acl|D_v)
 328     debug_printf_indent("Transport port=%d replaced by host-specific port=%d\n", port,
 329       host->port);
 330   port = host->port;
 331   }
 332 else host->port = port;    /* Set the port actually used */
 333 }
 334
 335
 336 /*************************************************
 337 *           Connect to remote host               *
 338 *************************************************/
 339
 340 /* Create a socket, and connect it to a remote host. IPv6 addresses are
 341 detected by checking for a colon in the address. AF_INET6 is defined even on
 342 non-IPv6 systems, to enable the code to be less messy. However, on such systems
 343 host->address will always be an IPv4 address.
 344
 345 Arguments:
 346   host        host item containing name and address and port
 347   host_af     AF_INET or AF_INET6
 348   interface   outgoing interface address or NULL
 349   timeout     timeout value or 0
 350   tb          transport
 351
 352 Returns:      connected socket number, or -1 with errno set
 353 */
 354
 355 int
 356 smtp_connect(host_item *host, int host_af, uschar *interface,
 357   int timeout, transport_instance * tb)
 358 {
 359 int port = host->port;
 360 #ifdef SUPPORT_SOCKS
 361 smtp_transport_options_block * ob =
 362   (smtp_transport_options_block *)tb->options_block;
 363 #endif
 364
 365 callout_address = string_sprintf("[%s]:%d", host->address, port);
 366
 367 HDEBUG(D_transport|D_acl|D_v)
 368   {
 369   uschar * s = US" ";
 370   if (interface) s = string_sprintf(" from %s ", interface);
 371 #ifdef SUPPORT_SOCKS
 372   if (ob->socks_proxy) s = string_sprintf("%svia proxy ", s);
 373 #endif
 374   debug_printf_indent("Connecting to %s %s%s... ", host->name, callout_address, s);
 375   }
 376
 377 /* Create and connect the socket */
 378
 379 #ifdef SUPPORT_SOCKS
 380 if (ob->socks_proxy)
 381   return socks_sock_connect(host, host_af, port, interface, tb, timeout);
 382 #endif
 383
 384 return smtp_sock_connect(host, host_af, port, interface, tb, timeout, NULL);
 385 }
 386
 387
 388 /*************************************************
 389 *        Flush outgoing command buffer           *
 390 *************************************************/
 391
 392 /* This function is called only from smtp_write_command() below. It flushes
 393 the buffer of outgoing commands. There is more than one in the buffer only when
 394 pipelining.
 395
 396 Argument:
 397   outblock   the SMTP output block
 398   mode       further data expected, or plain
 399
 400 Returns:     TRUE if OK, FALSE on error, with errno set
 401 */
 402
 403 static BOOL
 404 flush_buffer(smtp_outblock * outblock, int mode)
 405 {
 406 int rc;
 407 int n = outblock->ptr - outblock->buffer;
 408 BOOL more = mode == SCMD_MORE;
 409
 410 HDEBUG(D_transport|D_acl) debug_printf_indent("cmd buf flush %d bytes%s\n", n,
 411   more ? " (more expected)" : "");
 412
 413 #ifdef SUPPORT_TLS
 414 if (outblock->cctx->tls_ctx)
 415   rc = tls_write(outblock->cctx->tls_ctx, outblock->buffer, n, more);
 416 else
 417 #endif
 418   rc = send(outblock->cctx->sock, outblock->buffer, n,
 419 #ifdef MSG_MORE
 420             more ? MSG_MORE : 0
 421 #else
 422             0
 423 #endif
 424            );
 425
 426 if (rc <= 0)
 427   {
 428   HDEBUG(D_transport|D_acl) debug_printf_indent("send failed: %s\n", strerror(errno));
 429   return FALSE;
 430   }
 431
 432 outblock->ptr = outblock->buffer;
 433 outblock->cmd_count = 0;
 434 return TRUE;
 435 }
 436
 437
 438
 439 /*************************************************
 440 *             Write SMTP command                 *
 441 *************************************************/
 442
 443 /* The formatted command is left in big_buffer so that it can be reflected in
 444 any error message.
 445
 446 Arguments:
 447   sx         SMTP connection, contains buffer for pipelining, and socket
 448   mode       buffer, write-with-more-likely, write
 449   format     a format, starting with one of
 450              of HELO, MAIL FROM, RCPT TO, DATA, ".", or QUIT.
 451              If NULL, flush pipeline buffer only.
 452   ...        data for the format
 453
 454 Returns:     0 if command added to pipelining buffer, with nothing transmitted
 455             +n if n commands transmitted (may still have buffered the new one)
 456             -1 on error, with errno set
 457 */
 458
 459 int
 460 smtp_write_command(void * sx, int mode, const char *format, ...)
 461 {
 462 smtp_outblock * outblock = &((smtp_context *)sx)->outblock;
 463 int count;
 464 int rc = 0;
 465 va_list ap;
 466
 467 if (format)
 468   {
 469   va_start(ap, format);
 470   if (!string_vformat(big_buffer, big_buffer_size, CS format, ap))
 471     log_write(0, LOG_MAIN|LOG_PANIC_DIE, "overlong write_command in outgoing "
 472       "SMTP");
 473   va_end(ap);
 474   count = Ustrlen(big_buffer);
 475
 476   if (count > outblock->buffersize)
 477     log_write(0, LOG_MAIN|LOG_PANIC_DIE, "overlong write_command in outgoing "
 478       "SMTP");
 479
 480   if (count > outblock->buffersize - (outblock->ptr - outblock->buffer))
 481     {
 482     rc = outblock->cmd_count;                 /* flush resets */
 483     if (!flush_buffer(outblock, SCMD_FLUSH)) return -1;
 484     }
 485
 486   Ustrncpy(CS outblock->ptr, big_buffer, count);
 487   outblock->ptr += count;
 488   outblock->cmd_count++;
 489   count -= 2;
 490   big_buffer[count] = 0;     /* remove \r\n for error message */
 491
 492   /* We want to hide the actual data sent in AUTH transactions from reflections
 493   and logs. While authenticating, a flag is set in the outblock to enable this.
 494   The AUTH command itself gets any data flattened. Other lines are flattened
 495   completely. */
 496
 497   if (outblock->authenticating)
 498     {
 499     uschar *p = big_buffer;
 500     if (Ustrncmp(big_buffer, "AUTH ", 5) == 0)
 501       {
 502       p += 5;
 503       while (isspace(*p)) p++;
 504       while (!isspace(*p)) p++;
 505       while (isspace(*p)) p++;
 506       }
 507     while (*p != 0) *p++ = '*';
 508     }
 509
 510   HDEBUG(D_transport|D_acl|D_v) debug_printf_indent("  SMTP>> %s\n", big_buffer);
 511   }
 512
 513 if (mode != SCMD_BUFFER)
 514   {
 515   rc += outblock->cmd_count;                /* flush resets */
 516   if (!flush_buffer(outblock, mode)) return -1;
 517   }
 518
 519 return rc;
 520 }
 521
 522
 523
 524 /*************************************************
 525 *          Read one line of SMTP response        *
 526 *************************************************/
 527
 528 /* This function reads one line of SMTP response from the server host. This may
 529 not be a complete response - it could be just part of a multiline response. We
 530 have to use a buffer for incoming packets, because when pipelining or using
 531 LMTP, there may well be more than one response in a single packet. This
 532 function is called only from the one that follows.
 533
 534 Arguments:
 535   inblock   the SMTP input block (contains holding buffer, socket, etc.)
 536   buffer    where to put the line
 537   size      space available for the line
 538   timeout   the timeout to use when reading a packet
 539
 540 Returns:    length of a line that has been put in the buffer
 541             -1 otherwise, with errno set
 542 */
 543
 544 static int
 545 read_response_line(smtp_inblock *inblock, uschar *buffer, int size, int timeout)
 546 {
 547 uschar *p = buffer;
 548 uschar *ptr = inblock->ptr;
 549 uschar *ptrend = inblock->ptrend;
 550 client_conn_ctx * cctx = inblock->cctx;
 551
 552 /* Loop for reading multiple packets or reading another packet after emptying
 553 a previously-read one. */
 554
 555 for (;;)
 556   {
 557   int rc;
 558
 559   /* If there is data in the input buffer left over from last time, copy
 560   characters from it until the end of a line, at which point we can return,
 561   having removed any whitespace (which will include CR) at the end of the line.
 562   The rules for SMTP say that lines end in CRLF, but there are have been cases
 563   of hosts using just LF, and other MTAs are reported to handle this, so we
 564   just look for LF. If we run out of characters before the end of a line,
 565   carry on to read the next incoming packet. */
 566
 567   while (ptr < ptrend)
 568     {
 569     int c = *ptr++;
 570     if (c == '\n')
 571       {
 572       while (p > buffer && isspace(p[-1])) p--;
 573       *p = 0;
 574       inblock->ptr = ptr;
 575       return p - buffer;
 576       }
 577     *p++ = c;
 578     if (--size < 4)
 579       {
 580       *p = 0;                     /* Leave malformed line for error message */
 581       errno = ERRNO_SMTPFORMAT;
 582       return -1;
 583       }
 584     }
 585
 586   /* Need to read a new input packet. */
 587
 588   if((rc = ip_recv(cctx, inblock->buffer, inblock->buffersize, timeout)) <= 0)
 589     {
 590     DEBUG(D_deliver|D_transport|D_acl)
 591       debug_printf_indent(errno ? "  SMTP(%s)<<\n" : "  SMTP(closed)<<\n",
 592         strerror(errno));
 593     break;
 594     }
 595
 596   /* Another block of data has been successfully read. Set up the pointers
 597   and let the loop continue. */
 598
 599   ptrend = inblock->ptrend = inblock->buffer + rc;
 600   ptr = inblock->buffer;
 601   DEBUG(D_transport|D_acl) debug_printf_indent("read response data: size=%d\n", rc);
 602   }
 603
 604 /* Get here if there has been some kind of recv() error; errno is set, but we
 605 ensure that the result buffer is empty before returning. */
 606
 607 *buffer = 0;
 608 return -1;
 609 }
 610
 611
 612
 613
 614
 615 /*************************************************
 616 *              Read SMTP response                *
 617 *************************************************/
 618
 619 /* This function reads an SMTP response with a timeout, and returns the
 620 response in the given buffer, as a string. A multiline response will contain
 621 newline characters between the lines. The function also analyzes the first
 622 digit of the reply code and returns FALSE if it is not acceptable. FALSE is
 623 also returned after a reading error. In this case buffer[0] will be zero, and
 624 the error code will be in errno.
 625
 626 Arguments:
 627   sx        the SMTP connection (contains input block with holding buffer,
 628                 socket, etc.)
 629   buffer    where to put the response
 630   size      the size of the buffer
 631   okdigit   the expected first digit of the response
 632   timeout   the timeout to use, in seconds
 633
 634 Returns:    TRUE if a valid, non-error response was received; else FALSE
 635 */
 636
 637 BOOL
 638 smtp_read_response(void * sx, uschar *buffer, int size, int okdigit,
 639    int timeout)
 640 {
 641 smtp_inblock * inblock = &((smtp_context *)sx)->inblock;
 642 uschar *ptr = buffer;
 643 int count;
 644
 645 errno = 0;  /* Ensure errno starts out zero */
 646
 647 /* This is a loop to read and concatenate the lines that make up a multi-line
 648 response. */
 649
 650 for (;;)
 651   {
 652   if ((count = read_response_line(inblock, ptr, size, timeout)) < 0)
 653     return FALSE;
 654
 655   HDEBUG(D_transport|D_acl|D_v)
 656     debug_printf_indent("  %s %s\n", (ptr == buffer)? "SMTP<<" : "      ", ptr);
 657
 658   /* Check the format of the response: it must start with three digits; if
 659   these are followed by a space or end of line, the response is complete. If
 660   they are followed by '-' this is a multi-line response and we must look for
 661   another line until the final line is reached. The only use made of multi-line
 662   responses is to pass them back as error messages. We therefore just
 663   concatenate them all within the buffer, which should be large enough to
 664   accept any reasonable number of lines. */
 665
 666   if (count < 3 ||
 667      !isdigit(ptr[0]) ||
 668      !isdigit(ptr[1]) ||
 669      !isdigit(ptr[2]) ||
 670      (ptr[3] != '-' && ptr[3] != ' ' && ptr[3] != 0))
 671     {
 672     errno = ERRNO_SMTPFORMAT;    /* format error */
 673     return FALSE;
 674     }
 675
 676   /* If the line we have just read is a terminal line, line, we are done.
 677   Otherwise more data has to be read. */
 678
 679   if (ptr[3] != '-') break;
 680
 681   /* Move the reading pointer upwards in the buffer and insert \n between the
 682   components of a multiline response. Space is left for this by read_response_
 683   line(). */
 684
 685   ptr += count;
 686   *ptr++ = '\n';
 687   size -= count + 1;
 688   }
 689
 690 /* Return a value that depends on the SMTP return code. On some systems a
 691 non-zero value of errno has been seen at this point, so ensure it is zero,
 692 because the caller of this function looks at errno when FALSE is returned, to
 693 distinguish between an unexpected return code and other errors such as
 694 timeouts, lost connections, etc. */
 695
 696 errno = 0;
 697 return buffer[0] == okdigit;
 698 }
 699
 700 /* End of smtp_out.c */
 701 /* vi: aw ai sw=2
 702 */