/* $Cambridge: exim/src/src/smtp_out.c,v 1.10 2009/11/16 19:50:37 nm4 Exp $ */ /************************************************* * Exim - an Internet mail transport agent * *************************************************/ /* Copyright (c) University of Cambridge 1995 - 2009 */ /* See the file NOTICE for conditions of use and distribution. */ /* A number of functions for driving outgoing SMTP calls. */ #include "exim.h" /************************************************* * Find an outgoing interface * *************************************************/ /* This function is called from the smtp transport and also from the callout code in verify.c. Its job is to expand a string to get a list of interfaces, and choose a suitable one (IPv4 or IPv6) for the outgoing address. Arguments: istring string interface setting, may be NULL, meaning "any", in which case the function does nothing host_af AF_INET or AF_INET6 for the outgoing IP address addr the mail address being handled (for setting errors) changed if not NULL, set TRUE if expansion actually changed istring interface point this to the interface msg to add to any error message Returns: TRUE on success, FALSE on failure, with error message set in addr and transport_return set to PANIC */ BOOL smtp_get_interface(uschar *istring, int host_af, address_item *addr, BOOL *changed, uschar **interface, uschar *msg) { uschar *expint; uschar *iface; int sep = 0; if (istring == NULL) return TRUE; expint = expand_string(istring); if (expint == NULL) { if (expand_string_forcedfail) return TRUE; addr->transport_return = PANIC; addr->message = string_sprintf("failed to expand \"interface\" " "option for %s: %s", msg, expand_string_message); return FALSE; } if (changed != NULL) *changed = expint != istring; while (isspace(*expint)) expint++; if (*expint == 0) return TRUE; while ((iface = string_nextinlist(&expint, &sep, big_buffer, big_buffer_size)) != NULL) { if (string_is_ip_address(iface, NULL) == 0) { addr->transport_return = PANIC; addr->message = string_sprintf("\"%s\" is not a valid IP " "address for the \"interface\" option for %s", iface, msg); return FALSE; } if (((Ustrchr(iface, ':') == NULL)? AF_INET:AF_INET6) == host_af) break; } if (iface != NULL) *interface = string_copy(iface); return TRUE; } /************************************************* * Find an outgoing port * *************************************************/ /* This function is called from the smtp transport and also from the callout code in verify.c. Its job is to find a port number. Note that getservbyname() produces the number in network byte order. Arguments: rstring raw (unexpanded) string representation of the port addr the mail address being handled (for setting errors) port stick the port in here msg for adding to error message Returns: TRUE on success, FALSE on failure, with error message set in addr, and transport_return set to PANIC */ BOOL smtp_get_port(uschar *rstring, address_item *addr, int *port, uschar *msg) { uschar *pstring = expand_string(rstring); if (pstring == NULL) { addr->transport_return = PANIC; addr->message = string_sprintf("failed to expand \"%s\" (\"port\" option) " "for %s: %s", rstring, msg, expand_string_message); return FALSE; } if (isdigit(*pstring)) { uschar *end; *port = Ustrtol(pstring, &end, 0); if (end != pstring + Ustrlen(pstring)) { addr->transport_return = PANIC; addr->message = string_sprintf("invalid port number for %s: %s", msg, pstring); return FALSE; } } else { struct servent *smtp_service = getservbyname(CS pstring, "tcp"); if (smtp_service == NULL) { addr->transport_return = PANIC; addr->message = string_sprintf("TCP port \"%s\" is not defined for %s", pstring, msg); return FALSE; } *port = ntohs(smtp_service->s_port); } return TRUE; } /************************************************* * Connect to remote host * *************************************************/ /* Create a socket, and connect it to a remote host. IPv6 addresses are detected by checking for a colon in the address. AF_INET6 is defined even on non-IPv6 systems, to enable the code to be less messy. However, on such systems host->address will always be an IPv4 address. The port field in the host item is used if it is set (usually router from SRV records or elsewhere). In other cases, the default passed as an argument is used, and the host item is updated with its value. Arguments: host host item containing name and address (and sometimes port) host_af AF_INET or AF_INET6 port default remote port to connect to, in host byte order, for those hosts whose port setting is PORT_NONE interface outgoing interface address or NULL timeout timeout value or 0 keepalive TRUE to use keepalive Returns: connected socket number, or -1 with errno set */ int smtp_connect(host_item *host, int host_af, int port, uschar *interface, int timeout, BOOL keepalive) { int on = 1; int save_errno = 0; int sock; if (host->port != PORT_NONE) { HDEBUG(D_transport|D_acl|D_v) debug_printf("Transport port=%d replaced by host-specific port=%d\n", port, host->port); port = host->port; } else host->port = port; /* Set the port actually used */ HDEBUG(D_transport|D_acl|D_v) { if (interface == NULL) debug_printf("Connecting to %s [%s]:%d ... ",host->name,host->address,port); else debug_printf("Connecting to %s [%s]:%d from %s ... ", host->name, host->address, port, interface); } /* Create the socket */ if ((sock = ip_socket(SOCK_STREAM, host_af)) < 0) return -1; /* Set TCP_NODELAY; Exim does its own buffering. */ setsockopt(sock, IPPROTO_TCP, TCP_NODELAY, (uschar *)(&on), sizeof(on)); /* Bind to a specific interface if requested. Caller must ensure the interface is the same type (IPv4 or IPv6) as the outgoing address. */ if (interface != NULL && ip_bind(sock, host_af, interface, 0) < 0) { save_errno = errno; HDEBUG(D_transport|D_acl|D_v) debug_printf("unable to bind outgoing SMTP call to %s: %s", interface, strerror(errno)); } /* Connect to the remote host, and add keepalive to the socket before returning it, if requested. */ else if (ip_connect(sock, host_af, host->address, port, timeout) < 0) save_errno = errno; /* Either bind() or connect() failed */ if (save_errno != 0) { HDEBUG(D_transport|D_acl|D_v) { debug_printf("failed: %s", CUstrerror(save_errno)); if (save_errno == ETIMEDOUT) debug_printf(" (timeout=%s)", readconf_printtime(timeout)); debug_printf("\n"); } (void)close(sock); errno = save_errno; return -1; } /* Both bind() and connect() succeeded */ else { union sockaddr_46 interface_sock; EXIM_SOCKLEN_T size = sizeof(interface_sock); HDEBUG(D_transport|D_acl|D_v) debug_printf("connected\n"); if (getsockname(sock, (struct sockaddr *)(&interface_sock), &size) == 0) sending_ip_address = host_ntoa(-1, &interface_sock, NULL, &sending_port); else { log_write(0, LOG_MAIN | ((errno == ECONNRESET)? 0 : LOG_PANIC), "getsockname() failed: %s", strerror(errno)); close(sock); return -1; } if (keepalive) ip_keepalive(sock, host->address, TRUE); return sock; } } /************************************************* * Flush outgoing command buffer * *************************************************/ /* This function is called only from smtp_write_command() below. It flushes the buffer of outgoing commands. There is more than one in the buffer only when pipelining. Argument: outblock the SMTP output block Returns: TRUE if OK, FALSE on error, with errno set */ static BOOL flush_buffer(smtp_outblock *outblock) { int rc; #ifdef SUPPORT_TLS if (tls_active == outblock->sock) rc = tls_write(outblock->buffer, outblock->ptr - outblock->buffer); else #endif rc = send(outblock->sock, outblock->buffer, outblock->ptr - outblock->buffer, 0); if (rc <= 0) { HDEBUG(D_transport|D_acl) debug_printf("send failed: %s\n", strerror(errno)); return FALSE; } outblock->ptr = outblock->buffer; outblock->cmd_count = 0; return TRUE; } /************************************************* * Write SMTP command * *************************************************/ /* The formatted command is left in big_buffer so that it can be reflected in any error message. Arguments: outblock contains buffer for pipelining, and socket noflush if TRUE, save the command in the output buffer, for pipelining format a format, starting with one of of HELO, MAIL FROM, RCPT TO, DATA, ".", or QUIT. ... data for the format Returns: 0 if command added to pipelining buffer, with nothing transmitted +n if n commands transmitted (may still have buffered the new one) -1 on error, with errno set */ int smtp_write_command(smtp_outblock *outblock, BOOL noflush, const char *format, ...) { int count; int rc = 0; va_list ap; va_start(ap, format); if (!string_vformat(big_buffer, big_buffer_size, CS format, ap)) log_write(0, LOG_MAIN|LOG_PANIC_DIE, "overlong write_command in outgoing " "SMTP"); va_end(ap); count = Ustrlen(big_buffer); if (count > outblock->buffersize - (outblock->ptr - outblock->buffer)) { rc = outblock->cmd_count; /* flush resets */ if (!flush_buffer(outblock)) return -1; } Ustrncpy(CS outblock->ptr, big_buffer, count); outblock->ptr += count; outblock->cmd_count++; count -= 2; big_buffer[count] = 0; /* remove \r\n for error message */ /* We want to hide the actual data sent in AUTH transactions from reflections and logs. While authenticating, a flag is set in the outblock to enable this. The AUTH command itself gets any data flattened. Other lines are flattened completely. */ if (outblock->authenticating) { uschar *p = big_buffer; if (Ustrncmp(big_buffer, "AUTH ", 5) == 0) { p += 5; while (isspace(*p)) p++; while (!isspace(*p)) p++; while (isspace(*p)) p++; } while (*p != 0) *p++ = '*'; } HDEBUG(D_transport|D_acl|D_v) debug_printf(" SMTP>> %s\n", big_buffer); if (!noflush) { rc += outblock->cmd_count; /* flush resets */ if (!flush_buffer(outblock)) return -1; } return rc; } /************************************************* * Read one line of SMTP response * *************************************************/ /* This function reads one line of SMTP response from the server host. This may not be a complete response - it could be just part of a multiline response. We have to use a buffer for incoming packets, because when pipelining or using LMTP, there may well be more than one response in a single packet. This function is called only from the one that follows. Arguments: inblock the SMTP input block (contains holding buffer, socket, etc.) buffer where to put the line size space available for the line timeout the timeout to use when reading a packet Returns: length of a line that has been put in the buffer -1 otherwise, with errno set */ static int read_response_line(smtp_inblock *inblock, uschar *buffer, int size, int timeout) { uschar *p = buffer; uschar *ptr = inblock->ptr; uschar *ptrend = inblock->ptrend; int sock = inblock->sock; /* Loop for reading multiple packets or reading another packet after emptying a previously-read one. */ for (;;) { int rc; /* If there is data in the input buffer left over from last time, copy characters from it until the end of a line, at which point we can return, having removed any whitespace (which will include CR) at the end of the line. The rules for SMTP say that lines end in CRLF, but there are have been cases of hosts using just LF, and other MTAs are reported to handle this, so we just look for LF. If we run out of characters before the end of a line, carry on to read the next incoming packet. */ while (ptr < ptrend) { int c = *ptr++; if (c == '\n') { while (p > buffer && isspace(p[-1])) p--; *p = 0; inblock->ptr = ptr; return p - buffer; } *p++ = c; if (--size < 4) { *p = 0; /* Leave malformed line for error message */ errno = ERRNO_SMTPFORMAT; return -1; } } /* Need to read a new input packet. */ rc = ip_recv(sock, inblock->buffer, inblock->buffersize, timeout); if (rc <= 0) break; /* Another block of data has been successfully read. Set up the pointers and let the loop continue. */ ptrend = inblock->ptrend = inblock->buffer + rc; ptr = inblock->buffer; DEBUG(D_transport|D_acl) debug_printf("read response data: size=%d\n", rc); } /* Get here if there has been some kind of recv() error; errno is set, but we ensure that the result buffer is empty before returning. */ *buffer = 0; return -1; } /************************************************* * Read SMTP response * *************************************************/ /* This function reads an SMTP response with a timeout, and returns the response in the given buffer, as a string. A multiline response will contain newline characters between the lines. The function also analyzes the first digit of the reply code and returns FALSE if it is not acceptable. FALSE is also returned after a reading error. In this case buffer[0] will be zero, and the error code will be in errno. Arguments: inblock the SMTP input block (contains holding buffer, socket, etc.) buffer where to put the response size the size of the buffer okdigit the expected first digit of the response timeout the timeout to use Returns: TRUE if a valid, non-error response was received; else FALSE */ BOOL smtp_read_response(smtp_inblock *inblock, uschar *buffer, int size, int okdigit, int timeout) { uschar *ptr = buffer; int count; errno = 0; /* Ensure errno starts out zero */ /* This is a loop to read and concatentate the lines that make up a multi-line response. */ for (;;) { if ((count = read_response_line(inblock, ptr, size, timeout)) < 0) return FALSE; HDEBUG(D_transport|D_acl|D_v) debug_printf(" %s %s\n", (ptr == buffer)? "SMTP<<" : " ", ptr); /* Check the format of the response: it must start with three digits; if these are followed by a space or end of line, the response is complete. If they are followed by '-' this is a multi-line response and we must look for another line until the final line is reached. The only use made of multi-line responses is to pass them back as error messages. We therefore just concatenate them all within the buffer, which should be large enough to accept any reasonable number of lines. */ if (count < 3 || !isdigit(ptr[0]) || !isdigit(ptr[1]) || !isdigit(ptr[2]) || (ptr[3] != '-' && ptr[3] != ' ' && ptr[3] != 0)) { errno = ERRNO_SMTPFORMAT; /* format error */ return FALSE; } /* If the line we have just read is a terminal line, line, we are done. Otherwise more data has to be read. */ if (ptr[3] != '-') break; /* Move the reading pointer upwards in the buffer and insert \n between the components of a multiline response. Space is left for this by read_response_ line(). */ ptr += count; *ptr++ = '\n'; size -= count + 1; } /* Return a value that depends on the SMTP return code. On some systems a non-zero value of errno has been seen at this point, so ensure it is zero, because the caller of this function looks at errno when FALSE is returned, to distinguish between an unexpected return code and other errors such as timeouts, lost connections, etc. */ errno = 0; return buffer[0] == okdigit; } /* End of smtp_out.c */