--- /dev/null
+// This module is an SMTP and ESMTP server for the Citadel system.
+// It is compliant with all of the following:
+//
+// RFC 821 - Simple Mail Transfer Protocol
+// RFC 876 - Survey of SMTP Implementations
+// RFC 1047 - Duplicate messages and SMTP
+// RFC 1652 - 8 bit MIME
+// RFC 1869 - Extended Simple Mail Transfer Protocol
+// RFC 1870 - SMTP Service Extension for Message Size Declaration
+// RFC 2033 - Local Mail Transfer Protocol
+// RFC 2197 - SMTP Service Extension for Command Pipelining
+// RFC 2476 - Message Submission
+// RFC 2487 - SMTP Service Extension for Secure SMTP over TLS
+// RFC 2554 - SMTP Service Extension for Authentication
+// RFC 2821 - Simple Mail Transfer Protocol
+// RFC 2822 - Internet Message Format
+// RFC 2920 - SMTP Service Extension for Command Pipelining
+//
+// The VRFY and EXPN commands have been removed from this implementation
+// because nobody uses these commands anymore, except for spammers.
+//
+// Copyright (c) 1998-2022 by the citadel.org team
+//
+// This program is open source software; you can redistribute it and/or modify
+// it under the terms of the GNU General Public License version 3.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+#include "../../sysdep.h"
+#include <stdlib.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <termios.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <pwd.h>
+#include <errno.h>
+#include <sys/types.h>
+#include <syslog.h>
+#include <time.h>
+#include <sys/wait.h>
+#include <ctype.h>
+#include <string.h>
+#include <limits.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <libcitadel.h>
+#include "../../citadel.h"
+#include "../../server.h"
+#include "../../citserver.h"
+#include "../../support.h"
+#include "../../config.h"
+#include "../../control.h"
+#include "../../user_ops.h"
+#include "../../room_ops.h"
+#include "../../database.h"
+#include "../../msgbase.h"
+#include "../../internet_addressing.h"
+#include "../../genstamp.h"
+#include "../../domain.h"
+#include "../../clientsocket.h"
+#include "../../locate_host.h"
+#include "../../citadel_dirs.h"
+#include "../../ctdl_module.h"
+
+#include "smtp_util.h"
+
+enum { // Command states for login authentication
+ smtp_command,
+ smtp_user,
+ smtp_password,
+ smtp_plain
+};
+
+enum SMTP_FLAGS {
+ HELO,
+ EHLO,
+ LHLO
+};
+
+
+// Here's where our SMTP session begins its happy day.
+void smtp_greeting(int is_msa) {
+ char message_to_spammer[1024];
+
+ strcpy(CC->cs_clientname, "SMTP session");
+ CC->internal_pgm = 1;
+ CC->cs_flags |= CS_STEALTH;
+ CC->session_specific_data = malloc(sizeof(struct citsmtp));
+ memset(SMTP, 0, sizeof(struct citsmtp));
+ SMTP->is_msa = is_msa;
+ SMTP->Cmd = NewStrBufPlain(NULL, SIZ);
+ SMTP->helo_node = NewStrBuf();
+ SMTP->from = NewStrBufPlain(NULL, SIZ);
+ SMTP->recipients = NewStrBufPlain(NULL, SIZ);
+ SMTP->OneRcpt = NewStrBufPlain(NULL, SIZ);
+ SMTP->preferred_sender_email = NULL;
+ SMTP->preferred_sender_name = NULL;
+
+ // If this config option is set, reject connections from problem
+ // addresses immediately instead of after they execute a RCPT
+ if ( (CtdlGetConfigInt("c_rbl_at_greeting")) && (SMTP->is_msa == 0) ) {
+ if (rbl_check(CC->cs_addr, message_to_spammer)) {
+ if (server_shutting_down)
+ cprintf("421 %s\r\n", message_to_spammer);
+ else
+ cprintf("550 %s\r\n", message_to_spammer);
+ CC->kill_me = KILLME_SPAMMER;
+ /* no need to free_recipients(valid), it's not allocated yet */
+ return;
+ }
+ }
+
+ // Otherwise we're either clean or we check later.
+
+ if (CC->nologin==1) {
+ cprintf("451 Too many connections are already open; please try again later.\r\n");
+ CC->kill_me = KILLME_MAX_SESSIONS_EXCEEDED;
+ // no need to free_recipients(valid), it's not allocated yet
+ return;
+ }
+
+ // Note: the FQDN *must* appear as the first thing after the 220 code.
+ // Some clients (including citmail.c) depend on it being there.
+ cprintf("220 %s ESMTP Citadel server ready.\r\n", CtdlGetConfigStr("c_fqdn"));
+}
+
+
+// SMTPS is just like SMTP, except it goes crypto right away.
+void smtps_greeting(void) {
+ CtdlModuleStartCryptoMsgs(NULL, NULL, NULL);
+#ifdef HAVE_OPENSSL
+ if (!CC->redirect_ssl) CC->kill_me = KILLME_NO_CRYPTO; // kill session if no crypto
+#endif
+ smtp_greeting(0);
+}
+
+
+// SMTP MSA port requires authentication.
+void smtp_msa_greeting(void) {
+ smtp_greeting(1);
+}
+
+
+// LMTP is like SMTP but with some extra bonus footage added.
+void lmtp_greeting(void) {
+
+ smtp_greeting(0);
+ SMTP->is_lmtp = 1;
+}
+
+
+// Generic SMTP MTA greeting
+void smtp_mta_greeting(void) {
+ smtp_greeting(0);
+}
+
+
+// We also have an unfiltered LMTP socket that bypasses spam filters.
+void lmtp_unfiltered_greeting(void) {
+ smtp_greeting(0);
+ SMTP->is_lmtp = 1;
+ SMTP->is_unfiltered = 1;
+}
+
+
+// Login greeting common to all auth methods
+void smtp_auth_greeting(void) {
+ cprintf("235 Hello, %s\r\n", CC->user.fullname);
+ syslog(LOG_INFO, "serv_smtp: SMTP authenticated %s", CC->user.fullname);
+ CC->internal_pgm = 0;
+ CC->cs_flags &= ~CS_STEALTH;
+}
+
+
+// Implement HELO and EHLO commands.
+// which_command: 0=HELO, 1=EHLO, 2=LHLO
+void smtp_hello(int which_command) {
+
+ if (StrLength(SMTP->Cmd) >= 6) {
+ FlushStrBuf(SMTP->helo_node);
+ StrBufAppendBuf(SMTP->helo_node, SMTP->Cmd, 5);
+ }
+
+ if ( (which_command != LHLO) && (SMTP->is_lmtp) ) {
+ cprintf("500 Only LHLO is allowed when running LMTP\r\n");
+ return;
+ }
+
+ if ( (which_command == LHLO) && (SMTP->is_lmtp == 0) ) {
+ cprintf("500 LHLO is only allowed when running LMTP\r\n");
+ return;
+ }
+
+ if (which_command == HELO) {
+ cprintf("250 Hello %s (%s [%s])\r\n",
+ ChrPtr(SMTP->helo_node),
+ CC->cs_host,
+ CC->cs_addr
+ );
+ }
+ else {
+ if (which_command == EHLO) {
+ cprintf("250-Hello %s (%s [%s])\r\n",
+ ChrPtr(SMTP->helo_node),
+ CC->cs_host,
+ CC->cs_addr
+ );
+ }
+ else {
+ cprintf("250-Greetings and joyous salutations.\r\n");
+ }
+ cprintf("250-HELP\r\n");
+ cprintf("250-SIZE %ld\r\n", CtdlGetConfigLong("c_maxmsglen"));
+
+#ifdef HAVE_OPENSSL
+ // Offer TLS, but only if TLS is not already active.
+ // Furthermore, only offer TLS when running on
+ // the SMTP-MSA port, not on the SMTP-MTA port, due to
+ // questionable reliability of TLS in certain sending MTA's.
+ if ( (!CC->redirect_ssl) && (SMTP->is_msa) ) {
+ cprintf("250-STARTTLS\r\n");
+ }
+#endif
+
+ cprintf("250-AUTH LOGIN PLAIN\r\n"
+ "250-AUTH=LOGIN PLAIN\r\n"
+ "250 8BITMIME\r\n"
+ );
+ }
+}
+
+
+// Backend function for smtp_webcit_preferences_hack().
+// Look at a message and determine if it's the preferences file.
+void smtp_webcit_preferences_hack_backend(long msgnum, void *userdata) {
+ struct CtdlMessage *msg;
+ char **webcit_conf = (char **) userdata;
+
+ if (*webcit_conf) {
+ return; // already got it
+ }
+
+ msg = CtdlFetchMessage(msgnum, 1);
+ if (msg == NULL) {
+ return;
+ }
+
+ if ( !CM_IsEmpty(msg, eMsgSubject) && (!strcasecmp(msg->cm_fields[eMsgSubject], "__ WebCit Preferences __"))) {
+ // This is it! Change ownership of the message text so it doesn't get freed.
+ *webcit_conf = (char *)msg->cm_fields[eMesageText];
+ msg->cm_fields[eMesageText] = NULL;
+ }
+ CM_Free(msg);
+}
+
+
+// The configuration item for the user's preferred display name for outgoing email is, unfortunately,
+// stored in the account's WebCit configuration. We have to fetch it now.
+void smtp_webcit_preferences_hack(void) {
+ char config_roomname[ROOMNAMELEN];
+ char *webcit_conf = NULL;
+
+ snprintf(config_roomname, sizeof config_roomname, "%010ld.%s", CC->user.usernum, USERCONFIGROOM);
+ if (CtdlGetRoom(&CC->room, config_roomname) != 0) {
+ return;
+ }
+
+ // Find the WebCit configuration message
+ CtdlForEachMessage(MSGS_ALL, 1, NULL, NULL, NULL, smtp_webcit_preferences_hack_backend, (void *)&webcit_conf);
+
+ if (!webcit_conf) {
+ return;
+ }
+
+ // Parse the webcit configuration and attempt to do something useful with it
+ char *str = webcit_conf;
+ char *saveptr = str;
+ char *this_line = NULL;
+ while (this_line = strtok_r(str, "\n", &saveptr), this_line != NULL) {
+ str = NULL;
+ if (!strncasecmp(this_line, "defaultfrom|", 12)) {
+ SMTP->preferred_sender_email = NewStrBufPlain(&this_line[12], -1);
+ }
+ if (!strncasecmp(this_line, "defaultname|", 12)) {
+ SMTP->preferred_sender_name = NewStrBufPlain(&this_line[12], -1);
+ }
+ if ((!strncasecmp(this_line, "defaultname|", 12)) && (SMTP->preferred_sender_name == NULL)) {
+ SMTP->preferred_sender_name = NewStrBufPlain(&this_line[12], -1);
+ }
+
+ }
+ free(webcit_conf);
+}
+
+
+// Implement HELP command.
+void smtp_help(void) {
+ cprintf("214 RTFM http://www.ietf.org/rfc/rfc2821.txt\r\n");
+}
+
+
+void smtp_get_user(int offset) {
+ char buf[SIZ];
+
+ StrBuf *UserName = NewStrBufDup(SMTP->Cmd);
+ StrBufCutLeft(UserName, offset);
+ StrBufDecodeBase64(UserName);
+
+ if (CtdlLoginExistingUser(ChrPtr(UserName)) == login_ok) {
+ size_t len = CtdlEncodeBase64(buf, "Password:", 9, 0);
+
+ if (buf[len - 1] == '\n') {
+ buf[len - 1] = '\0';
+ }
+ cprintf("334 %s\r\n", buf);
+ SMTP->command_state = smtp_password;
+ }
+ else {
+ cprintf("500 No such user.\r\n");
+ SMTP->command_state = smtp_command;
+ }
+ FreeStrBuf(&UserName);
+}
+
+
+void smtp_get_pass(void) {
+ char password[SIZ];
+
+ memset(password, 0, sizeof(password));
+ StrBufDecodeBase64(SMTP->Cmd);
+ syslog(LOG_DEBUG, "serv_smtp: trying <%s>", password);
+ if (CtdlTryPassword(SKEY(SMTP->Cmd)) == pass_ok) {
+ smtp_auth_greeting();
+ }
+ else {
+ cprintf("535 Authentication failed.\r\n");
+ }
+ SMTP->command_state = smtp_command;
+}
+
+
+// Back end for PLAIN auth method (either inline or multistate)
+void smtp_try_plain(void) {
+ const char*decoded_authstring;
+ char ident[256] = "";
+ char user[256] = "";
+ char pass[256] = "";
+ int result;
+
+ long decoded_len;
+ long len = 0;
+ long plen = 0;
+
+ memset(pass, 0, sizeof(pass));
+ decoded_len = StrBufDecodeBase64(SMTP->Cmd);
+
+ if (decoded_len > 0) {
+ decoded_authstring = ChrPtr(SMTP->Cmd);
+
+ len = safestrncpy(ident, decoded_authstring, sizeof ident);
+
+ decoded_len -= len - 1;
+ decoded_authstring += len + 1;
+
+ if (decoded_len > 0) {
+ len = safestrncpy(user, decoded_authstring, sizeof user);
+
+ decoded_authstring += len + 1;
+ decoded_len -= len - 1;
+ }
+
+ if (decoded_len > 0) {
+ plen = safestrncpy(pass, decoded_authstring, sizeof pass);
+
+ if (plen < 0)
+ plen = sizeof(pass) - 1;
+ }
+ }
+
+ SMTP->command_state = smtp_command;
+
+ if (!IsEmptyStr(ident)) {
+ result = CtdlLoginExistingUser(ident);
+ }
+ else {
+ result = CtdlLoginExistingUser(user);
+ }
+
+ if (result == login_ok) {
+ if (CtdlTryPassword(pass, plen) == pass_ok) {
+ smtp_webcit_preferences_hack();
+ smtp_auth_greeting();
+ return;
+ }
+ }
+ cprintf("504 Authentication failed.\r\n");
+}
+
+
+// Attempt to perform authenticated SMTP
+void smtp_auth(void) {
+ char username_prompt[64];
+ char method[64];
+ char encoded_authstring[1024];
+
+ if (CC->logged_in) {
+ cprintf("504 Already logged in.\r\n");
+ return;
+ }
+
+ if (StrLength(SMTP->Cmd) < 6) {
+ cprintf("501 Syntax error\r\n");
+ return;
+ }
+
+ extract_token(method, ChrPtr(SMTP->Cmd) + 5, 0, ' ', sizeof method);
+
+ if (!strncasecmp(method, "login", 5) ) {
+ if (StrLength(SMTP->Cmd) >= 12) {
+ syslog(LOG_DEBUG, "serv_smtp: username <%s> supplied inline", ChrPtr(SMTP->Cmd)+11);
+ smtp_get_user(11);
+ }
+ else {
+ size_t len = CtdlEncodeBase64(username_prompt, "Username:", 9, 0);
+ if (username_prompt[len - 1] == '\n') {
+ username_prompt[len - 1] = '\0';
+ }
+ cprintf("334 %s\r\n", username_prompt);
+ SMTP->command_state = smtp_user;
+ }
+ return;
+ }
+
+ if (!strncasecmp(method, "plain", 5) ) {
+ long len;
+ if (num_tokens(ChrPtr(SMTP->Cmd) + 5, ' ') < 2) {
+ cprintf("334 \r\n");
+ SMTP->command_state = smtp_plain;
+ return;
+ }
+
+ len = extract_token(encoded_authstring,
+ ChrPtr(SMTP->Cmd) + 5,
+ 1, ' ',
+ sizeof encoded_authstring);
+ StrBufPlain(SMTP->Cmd, encoded_authstring, len);
+ smtp_try_plain();
+ return;
+ }
+
+ cprintf("504 Unknown authentication method.\r\n");
+ return;
+}
+
+
+// Implements the RSET (reset state) command.
+// Currently this just zeroes out the state buffer. If pointers to data
+// allocated with malloc() are ever placed in the state buffer, we have to
+// be sure to free() them first!
+//
+// Set do_response to nonzero to output the SMTP RSET response code.
+void smtp_rset(int do_response) {
+ FlushStrBuf(SMTP->Cmd);
+ FlushStrBuf(SMTP->helo_node);
+ FlushStrBuf(SMTP->from);
+ FlushStrBuf(SMTP->recipients);
+ FlushStrBuf(SMTP->OneRcpt);
+
+ SMTP->command_state = 0;
+ SMTP->number_of_recipients = 0;
+ SMTP->delivery_mode = 0;
+ SMTP->message_originated_locally = 0;
+ SMTP->is_msa = 0;
+ // is_lmtp and is_unfiltered should not be cleared.
+
+ if (do_response) {
+ cprintf("250 Zap!\r\n");
+ }
+}
+
+
+// Clear out the portions of the state buffer that need to be cleared out
+// after the DATA command finishes.
+void smtp_data_clear(void) {
+ FlushStrBuf(SMTP->from);
+ FlushStrBuf(SMTP->recipients);
+ FlushStrBuf(SMTP->OneRcpt);
+ SMTP->number_of_recipients = 0;
+ SMTP->delivery_mode = 0;
+ SMTP->message_originated_locally = 0;
+}
+
+
+// Implements the "MAIL FROM:" command
+void smtp_mail(void) {
+ char user[SIZ];
+ char node[SIZ];
+ char name[SIZ];
+
+ if (StrLength(SMTP->from) > 0) {
+ cprintf("503 Only one sender permitted\r\n");
+ return;
+ }
+
+ if (StrLength(SMTP->Cmd) < 6) {
+ cprintf("501 Syntax error\r\n");
+ return;
+ }
+
+ if (strncasecmp(ChrPtr(SMTP->Cmd) + 5, "From:", 5)) {
+ cprintf("501 Syntax error\r\n");
+ return;
+ }
+
+ StrBufAppendBuf(SMTP->from, SMTP->Cmd, 5);
+ StrBufTrim(SMTP->from);
+ if (strchr(ChrPtr(SMTP->from), '<') != NULL) {
+ StrBufStripAllBut(SMTP->from, '<', '>');
+ }
+
+ // We used to reject empty sender names, until it was brought to our
+ // attention that RFC1123 5.2.9 requires that this be allowed. So now
+ // we allow it, but replace the empty string with a fake
+ // address so we don't have to contend with the empty string causing
+ // other code to fail when it's expecting something there.
+ if (StrLength(SMTP->from) == 0) {
+ StrBufPlain(SMTP->from, HKEY("someone@example.com"));
+ }
+
+ // If this SMTP connection is from a logged-in user, force the 'from'
+ // to be the user's Internet e-mail address as Citadel knows it.
+ if (CC->logged_in) {
+ StrBufPlain(SMTP->from, CC->cs_inet_email, -1);
+ cprintf("250 Sender ok <%s>\r\n", ChrPtr(SMTP->from));
+ SMTP->message_originated_locally = 1;
+ return;
+ }
+
+ else if (SMTP->is_lmtp) {
+ // Bypass forgery checking for LMTP
+ }
+
+ // Otherwise, make sure outsiders aren't trying to forge mail from
+ // this system (unless, of course, c_allow_spoofing is enabled)
+ else if (CtdlGetConfigInt("c_allow_spoofing") == 0) {
+ process_rfc822_addr(ChrPtr(SMTP->from), user, node, name);
+ syslog(LOG_DEBUG, "serv_smtp: claimed envelope sender is '%s' == '%s' @ '%s' ('%s')",
+ ChrPtr(SMTP->from), user, node, name
+ );
+ if (CtdlHostAlias(node) != hostalias_nomatch) {
+ cprintf("550 You must log in to send mail from %s\r\n", node);
+ FlushStrBuf(SMTP->from);
+ syslog(LOG_DEBUG, "serv_smtp: rejecting unauthenticated mail from %s", node);
+ return;
+ }
+ }
+
+ cprintf("250 Sender ok\r\n");
+}
+
+
+// Implements the "RCPT To:" command
+void smtp_rcpt(void) {
+ char message_to_spammer[SIZ];
+ struct recptypes *valid = NULL;
+
+ if (StrLength(SMTP->from) == 0) {
+ cprintf("503 Need MAIL before RCPT\r\n");
+ return;
+ }
+
+ if (StrLength(SMTP->Cmd) < 6) {
+ cprintf("501 Syntax error\r\n");
+ return;
+ }
+
+ if (strncasecmp(ChrPtr(SMTP->Cmd) + 5, "To:", 3)) {
+ cprintf("501 Syntax error\r\n");
+ return;
+ }
+
+ if ( (SMTP->is_msa) && (!CC->logged_in) ) {
+ cprintf("550 You must log in to send mail on this port.\r\n");
+ FlushStrBuf(SMTP->from);
+ return;
+ }
+
+ FlushStrBuf(SMTP->OneRcpt);
+ StrBufAppendBuf(SMTP->OneRcpt, SMTP->Cmd, 8);
+ StrBufTrim(SMTP->OneRcpt);
+ StrBufStripAllBut(SMTP->OneRcpt, '<', '>');
+
+ if ( (StrLength(SMTP->OneRcpt) + StrLength(SMTP->recipients)) >= SIZ) {
+ cprintf("452 Too many recipients\r\n");
+ return;
+ }
+
+ // RBL check
+ if (
+ (!CC->logged_in) // Don't RBL authenticated users
+ && (!SMTP->is_lmtp) // Don't RBL LMTP clients
+ && (CtdlGetConfigInt("c_rbl_at_greeting") == 0) // Don't RBL if we did it at connection time
+ && (rbl_check(CC->cs_addr, message_to_spammer))
+ ) {
+ cprintf("550 %s\r\n", message_to_spammer);
+ return; // no need to free_recipients(valid)
+ } // because it hasn't been allocated yet
+
+ // This is a *preliminary* call to validate_recipients() to evaluate one recipient.
+ valid = validate_recipients(
+ (char *)ChrPtr(SMTP->OneRcpt),
+ smtp_get_Recipients(),
+ (SMTP->is_lmtp)? POST_LMTP: (CC->logged_in)? POST_LOGGED_IN: POST_EXTERNAL
+ );
+
+ // Any type of error thrown by validate_recipients() will make the SMTP transaction fail at this point.
+ if (valid->num_error != 0) {
+ cprintf("550 %s\r\n", valid->errormsg);
+ free_recipients(valid);
+ return;
+ }
+
+ if (
+ (valid->num_internet > 0) // If it's outbound Internet mail...
+ && (CC->logged_in) // ...and we're a logged-in user...
+ && (CtdlCheckInternetMailPermission(&CC->user)==0) // ...who does not have Internet mail rights...
+ ) {
+ cprintf("551 <%s> - you do not have permission to send Internet mail\r\n", ChrPtr(SMTP->OneRcpt));
+ free_recipients(valid);
+ return;
+ }
+
+ if (
+ (valid->num_internet > 0) // If it's outbound Internet mail...
+ && (SMTP->message_originated_locally == 0) // ...and also inbound Internet mail...
+ && (SMTP->is_lmtp == 0) /// ...and didn't arrive via LMTP...
+ ) {
+ cprintf("551 <%s> - relaying denied\r\n", ChrPtr(SMTP->OneRcpt));
+ free_recipients(valid);
+ return;
+ }
+
+ if (
+ (valid->num_room > 0) // If it's mail to a room (mailing list)...
+ && (SMTP->message_originated_locally == 0) // ...and also inbound Internet mail...
+ && (is_email_subscribed_to_list((char *)ChrPtr(SMTP->from), valid->recp_room) == 0) // ...and not a subscriber
+ ) {
+ cprintf("551 <%s> - The message is not from a list member\r\n", ChrPtr(SMTP->OneRcpt));
+ free_recipients(valid);
+ return;
+ }
+
+ cprintf("250 RCPT ok <%s>\r\n", ChrPtr(SMTP->OneRcpt));
+ if (StrLength(SMTP->recipients) > 0) {
+ StrBufAppendBufPlain(SMTP->recipients, HKEY(","), 0);
+ }
+ StrBufAppendBuf(SMTP->recipients, SMTP->OneRcpt, 0);
+ SMTP->number_of_recipients ++;
+ if (valid != NULL) {
+ free_recipients(valid);
+ }
+}
+
+
+// Implements the DATA command
+void smtp_data(void) {
+ StrBuf *body;
+ StrBuf *defbody;
+ struct CtdlMessage *msg = NULL;
+ long msgnum = (-1L);
+ char nowstamp[SIZ];
+ struct recptypes *valid;
+ int scan_errors;
+ int i;
+
+ if (StrLength(SMTP->from) == 0) {
+ cprintf("503 Need MAIL command first.\r\n");
+ return;
+ }
+
+ if (SMTP->number_of_recipients < 1) {
+ cprintf("503 Need RCPT command first.\r\n");
+ return;
+ }
+
+ cprintf("354 Transmit message now - terminate with '.' by itself\r\n");
+
+ datestring(nowstamp, sizeof nowstamp, time(NULL), DATESTRING_RFC822);
+ defbody = NewStrBufPlain(NULL, SIZ);
+
+ if (defbody != NULL) {
+ if (SMTP->is_lmtp && (CC->cs_UDSclientUID != -1)) {
+ StrBufPrintf(
+ defbody,
+ "Received: from %s (Citadel from userid %ld)\n"
+ " by %s; %s\n",
+ ChrPtr(SMTP->helo_node),
+ (long int) CC->cs_UDSclientUID,
+ CtdlGetConfigStr("c_fqdn"),
+ nowstamp);
+ }
+ else {
+ StrBufPrintf(
+ defbody,
+ "Received: from %s (%s [%s])\n"
+ " by %s; %s\n",
+ ChrPtr(SMTP->helo_node),
+ CC->cs_host,
+ CC->cs_addr,
+ CtdlGetConfigStr("c_fqdn"),
+ nowstamp);
+ }
+ }
+ body = CtdlReadMessageBodyBuf(HKEY("."), CtdlGetConfigLong("c_maxmsglen"), defbody, 1);
+ FreeStrBuf(&defbody);
+ if (body == NULL) {
+ cprintf("550 Unable to save message: internal error.\r\n");
+ return;
+ }
+
+ syslog(LOG_DEBUG, "serv_smtp: converting message...");
+ msg = convert_internet_message_buf(&body);
+
+ // If the user is locally authenticated, FORCE the From: header to
+ // show up as the real sender. Yes, this violates the RFC standard,
+ // but IT MAKES SENSE. If you prefer strict RFC adherence over
+ // common sense, you can disable this in the configuration.
+ //
+ // We also set the "message room name" ('O' field) to MAILROOM
+ // (which is Mail> on most systems) to prevent it from getting set
+ // to something ugly like "0000058008.Sent Items>" when the message
+ // is read with a Citadel client.
+
+ if ( (CC->logged_in) && (CtdlGetConfigInt("c_rfc822_strict_from") != CFG_SMTP_FROM_NOFILTER) ) {
+ int validemail = 0;
+
+ if (!CM_IsEmpty(msg, erFc822Addr) &&
+ ((CtdlGetConfigInt("c_rfc822_strict_from") == CFG_SMTP_FROM_CORRECT) ||
+ (CtdlGetConfigInt("c_rfc822_strict_from") == CFG_SMTP_FROM_REJECT) ) )
+ {
+ if (!IsEmptyStr(CC->cs_inet_email))
+ validemail = strcmp(CC->cs_inet_email, msg->cm_fields[erFc822Addr]) == 0;
+ if ((!validemail) &&
+ (!IsEmptyStr(CC->cs_inet_other_emails)))
+ {
+ int num_secondary_emails = 0;
+ int i;
+ num_secondary_emails = num_tokens(CC->cs_inet_other_emails, '|');
+ for (i=0; i < num_secondary_emails && !validemail; ++i) {
+ char buf[256];
+ extract_token(buf, CC->cs_inet_other_emails,i,'|',sizeof CC->cs_inet_other_emails);
+ validemail = strcmp(buf, msg->cm_fields[erFc822Addr]) == 0;
+ }
+ }
+ }
+
+ if (!validemail && (CtdlGetConfigInt("c_rfc822_strict_from") == CFG_SMTP_FROM_REJECT)) {
+ syslog(LOG_ERR, "serv_smtp: invalid sender '%s' - rejecting this message", msg->cm_fields[erFc822Addr]);
+ cprintf("550 Invalid sender '%s' - rejecting this message.\r\n", msg->cm_fields[erFc822Addr]);
+ return;
+ }
+
+ CM_SetField(msg, eOriginalRoom, HKEY(MAILROOM));
+ if (SMTP->preferred_sender_name != NULL)
+ CM_SetField(msg, eAuthor, SKEY(SMTP->preferred_sender_name));
+ else
+ CM_SetField(msg, eAuthor, CC->user.fullname, strlen(CC->user.fullname));
+
+ if (!validemail) {
+ if (SMTP->preferred_sender_email != NULL) {
+ CM_SetField(msg, erFc822Addr, SKEY(SMTP->preferred_sender_email));
+ }
+ else {
+ CM_SetField(msg, erFc822Addr, CC->cs_inet_email, strlen(CC->cs_inet_email));
+ }
+ }
+ }
+
+ // Set the "envelope from" address
+ CM_SetField(msg, eMessagePath, SKEY(SMTP->from));
+
+ // Set the "envelope to" address
+ CM_SetField(msg, eenVelopeTo, SKEY(SMTP->recipients));
+
+ // Submit the message into the Citadel system.
+ valid = validate_recipients(
+ (char *)ChrPtr(SMTP->recipients),
+ smtp_get_Recipients(),
+ (SMTP->is_lmtp)? POST_LMTP: (CC->logged_in)? POST_LOGGED_IN: POST_EXTERNAL
+ );
+
+ // If there are modules that want to scan this message before final
+ // submission (such as virus checkers or spam filters), call them now
+ // and give them an opportunity to reject the message.
+ if (SMTP->is_unfiltered) {
+ scan_errors = 0;
+ }
+ else {
+ scan_errors = PerformMessageHooks(msg, valid, EVT_SMTPSCAN);
+ }
+
+ if (scan_errors > 0) { // We don't want this message!
+
+ if (CM_IsEmpty(msg, eErrorMsg)) {
+ CM_SetField(msg, eErrorMsg, HKEY("Message rejected by filter"));
+ }
+
+ StrBufPrintf(SMTP->OneRcpt, "550 %s\r\n", msg->cm_fields[eErrorMsg]);
+ }
+
+ else { // Ok, we'll accept this message.
+ msgnum = CtdlSubmitMsg(msg, valid, "");
+ if (msgnum > 0L) {
+ StrBufPrintf(SMTP->OneRcpt, "250 Message accepted.\r\n");
+ }
+ else {
+ StrBufPrintf(SMTP->OneRcpt, "550 Internal delivery error\r\n");
+ }
+ }
+
+ // For SMTP and ESMTP, just print the result message. For LMTP, we
+ // have to print one result message for each recipient. Since there
+ // is nothing in Citadel which would cause different recipients to
+ // have different results, we can get away with just spitting out the
+ // same message once for each recipient.
+ if (SMTP->is_lmtp) {
+ for (i=0; i<SMTP->number_of_recipients; ++i) {
+ cputbuf(SMTP->OneRcpt);
+ }
+ }
+ else {
+ cputbuf(SMTP->OneRcpt);
+ }
+
+ // Write something to the syslog(which may or may not be where the
+ // rest of the Citadel logs are going; some sysadmins want LOG_MAIL).
+ syslog((LOG_MAIL | LOG_INFO),
+ "%ld: from=<%s>, nrcpts=%d, relay=%s [%s], stat=%s",
+ msgnum,
+ ChrPtr(SMTP->from),
+ SMTP->number_of_recipients,
+ CC->cs_host,
+ CC->cs_addr,
+ ChrPtr(SMTP->OneRcpt)
+ );
+
+ // Clean up
+ CM_Free(msg);
+ free_recipients(valid);
+ smtp_data_clear(); // clear out the buffers now
+}
+
+
+// Implements the STARTTLS command
+void smtp_starttls(void) {
+ char ok_response[SIZ];
+ char nosup_response[SIZ];
+ char error_response[SIZ];
+
+ sprintf(ok_response, "220 Begin TLS negotiation now\r\n");
+ sprintf(nosup_response, "554 TLS not supported here\r\n");
+ sprintf(error_response, "554 Internal error\r\n");
+ CtdlModuleStartCryptoMsgs(ok_response, nosup_response, error_response);
+ smtp_rset(0);
+}
+
+
+// Implements the NOOP (NO OPeration) command
+void smtp_noop(void) {
+ cprintf("250 NOOP\r\n");
+}
+
+
+// Implements the QUIT command
+void smtp_quit(void) {
+ cprintf("221 Goodbye...\r\n");
+ CC->kill_me = KILLME_CLIENT_LOGGED_OUT;
+}
+
+
+// Main command loop for SMTP server sessions.
+void smtp_command_loop(void) {
+ static const ConstStr AuthPlainStr = {HKEY("AUTH PLAIN")};
+
+ if (SMTP == NULL) {
+ syslog(LOG_ERR, "serv_smtp: Session SMTP data is null. WTF? We will crash now.");
+ abort();
+ }
+
+ time(&CC->lastcmd);
+ if (CtdlClientGetLine(SMTP->Cmd) < 1) {
+ syslog(LOG_INFO, "SMTP: client disconnected: ending session.");
+ CC->kill_me = KILLME_CLIENT_DISCONNECTED;
+ return;
+ }
+
+ if (SMTP->command_state == smtp_user) {
+ if (!strncmp(ChrPtr(SMTP->Cmd), AuthPlainStr.Key, AuthPlainStr.len)) {
+ smtp_try_plain();
+ }
+ else {
+ smtp_get_user(0);
+ }
+ return;
+ }
+
+ else if (SMTP->command_state == smtp_password) {
+ smtp_get_pass();
+ return;
+ }
+
+ else if (SMTP->command_state == smtp_plain) {
+ smtp_try_plain();
+ return;
+ }
+
+ syslog(LOG_DEBUG, "serv_smtp: client sent command <%s>", ChrPtr(SMTP->Cmd));
+
+ if (!strncasecmp(ChrPtr(SMTP->Cmd), "NOOP", 4)) {
+ smtp_noop();
+ return;
+ }
+
+ if (!strncasecmp(ChrPtr(SMTP->Cmd), "QUIT", 4)) {
+ smtp_quit();
+ return;
+ }
+
+ if (!strncasecmp(ChrPtr(SMTP->Cmd), "HELO", 4)) {
+ smtp_hello(HELO);
+ return;
+ }
+
+ if (!strncasecmp(ChrPtr(SMTP->Cmd), "EHLO", 4)) {
+ smtp_hello(EHLO);
+ return;
+ }
+
+ if (!strncasecmp(ChrPtr(SMTP->Cmd), "LHLO", 4)) {
+ smtp_hello(LHLO);
+ return;
+ }
+
+ if (!strncasecmp(ChrPtr(SMTP->Cmd), "RSET", 4)) {
+ smtp_rset(1);
+ return;
+ }
+
+ if (!strncasecmp(ChrPtr(SMTP->Cmd), "AUTH", 4)) {
+ smtp_auth();
+ return;
+ }
+
+ if (!strncasecmp(ChrPtr(SMTP->Cmd), "DATA", 4)) {
+ smtp_data();
+ return;
+ }
+
+ if (!strncasecmp(ChrPtr(SMTP->Cmd), "HELP", 4)) {
+ smtp_help();
+ return;
+ }
+
+ if (!strncasecmp(ChrPtr(SMTP->Cmd), "MAIL", 4)) {
+ smtp_mail();
+ return;
+ }
+
+ if (!strncasecmp(ChrPtr(SMTP->Cmd), "RCPT", 4)) {
+ smtp_rcpt();
+ return;
+ }
+#ifdef HAVE_OPENSSL
+ if (!strncasecmp(ChrPtr(SMTP->Cmd), "STARTTLS", 8)) {
+ smtp_starttls();
+ return;
+ }
+#endif
+
+ cprintf("502 I'm afraid I can't do that.\r\n");
+}
+
+
+/*****************************************************************************/
+/* MODULE INITIALIZATION STUFF */
+/*****************************************************************************/
+/*
+ * This cleanup function blows away the temporary memory used by
+ * the SMTP server.
+ */
+void smtp_cleanup_function(void)
+{
+ /* Don't do this stuff if this is not an SMTP session! */
+ if (CC->h_command_function != smtp_command_loop) return;
+
+ syslog(LOG_DEBUG, "Performing SMTP cleanup hook");
+
+ FreeStrBuf(&SMTP->Cmd);
+ FreeStrBuf(&SMTP->helo_node);
+ FreeStrBuf(&SMTP->from);
+ FreeStrBuf(&SMTP->recipients);
+ FreeStrBuf(&SMTP->OneRcpt);
+ FreeStrBuf(&SMTP->preferred_sender_email);
+ FreeStrBuf(&SMTP->preferred_sender_name);
+
+ free(SMTP);
+}
+
+const char *CitadelServiceSMTP_MTA="SMTP-MTA";
+const char *CitadelServiceSMTPS_MTA="SMTPs-MTA";
+const char *CitadelServiceSMTP_MSA="SMTP-MSA";
+const char *CitadelServiceSMTP_LMTP="LMTP";
+const char *CitadelServiceSMTP_LMTP_UNF="LMTP-UnF";
+
+
+char *ctdl_module_init_smtp(void) {
+ if (!threading) {
+ CtdlRegisterServiceHook(CtdlGetConfigInt("c_smtp_port"), /* SMTP MTA */
+ NULL,
+ smtp_mta_greeting,
+ smtp_command_loop,
+ NULL,
+ CitadelServiceSMTP_MTA);
+
+#ifdef HAVE_OPENSSL
+ CtdlRegisterServiceHook(CtdlGetConfigInt("c_smtps_port"), /* SMTPS MTA */
+ NULL,
+ smtps_greeting,
+ smtp_command_loop,
+ NULL,
+ CitadelServiceSMTPS_MTA);
+#endif
+
+ CtdlRegisterServiceHook(CtdlGetConfigInt("c_msa_port"), /* SMTP MSA */
+ NULL,
+ smtp_msa_greeting,
+ smtp_command_loop,
+ NULL,
+ CitadelServiceSMTP_MSA);
+
+ CtdlRegisterServiceHook(0, /* local LMTP */
+ file_lmtp_socket,
+ lmtp_greeting,
+ smtp_command_loop,
+ NULL,
+ CitadelServiceSMTP_LMTP);
+
+ CtdlRegisterServiceHook(0, /* local LMTP */
+ file_lmtp_unfiltered_socket,
+ lmtp_unfiltered_greeting,
+ smtp_command_loop,
+ NULL,
+ CitadelServiceSMTP_LMTP_UNF);
+
+ CtdlRegisterSessionHook(smtp_cleanup_function, EVT_STOP, PRIO_STOP + 250);
+ }
+
+ /* return our module name for the log */
+ return "smtp";
+}
projects / citadel.git / blobdiff