-/*
- * 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) 1998-2021 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.
- */
+// 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 "smtp_util.h"
-enum { /* Command states for login authentication */
+enum { // Command states for login authentication
smtp_command,
smtp_user,
smtp_password,
};
-/*
- * Here's where our SMTP session begins its happy day.
- */
+// Here's where our SMTP session begins its happy day.
void smtp_greeting(int is_msa) {
char message_to_spammer[1024];
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 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)
}
}
- /* Otherwise we're either clean or we check later. */
+ // 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 */
+ // 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.
- */
+ // 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.
- */
+// 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 */
+ if (!CC->redirect_ssl) CC->kill_me = KILLME_NO_CRYPTO; // kill session if no crypto
#endif
smtp_greeting(0);
}
-/*
- * SMTP MSA port requires authentication.
- */
+// SMTP MSA port requires authentication.
void smtp_msa_greeting(void) {
smtp_greeting(1);
}
-/*
- * LMTP is like SMTP but with some extra bonus footage added.
- */
+// LMTP is like SMTP but with some extra bonus footage added.
void lmtp_greeting(void) {
smtp_greeting(0);
}
-/*
- * Generic SMTP MTA greeting
- */
+// Generic SMTP MTA greeting
void smtp_mta_greeting(void) {
smtp_greeting(0);
}
-/*
- * We also have an unfiltered LMTP socket that bypasses spam filters.
- */
+// We also have an unfiltered LMTP socket that bypasses spam filters.
void lmtp_unfiltered_greeting(void) {
smtp_greeting(0);
SMTP->is_lmtp = 1;
}
-/*
- * Login greeting common to all auth methods
- */
+// 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);
}
-/*
- * Implement HELO and EHLO commands.
- *
- * which_command: 0=HELO, 1=EHLO, 2=LHLO
- */
+// 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);
}
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.
- */
+ // 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 /* HAVE_OPENSSL */
+#endif
cprintf("250-AUTH LOGIN PLAIN\r\n"
"250-AUTH=LOGIN PLAIN\r\n"
}
-/*
- * Backend function for smtp_webcit_preferences_hack().
- * Look at a message and determine if it's the preferences file.
- */
+// 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
+ return; // already got it
}
msg = CtdlFetchMessage(msgnum, 1);
}
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. */
+ // 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;
}
}
-/*
- * 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.
- */
+// 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;
return;
}
- /*
- * Find the WebCit configuration message
- */
-
+ // 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 */
+ // Parse the webcit configuration and attempt to do something useful with it
char *str = webcit_conf;
char *saveptr = str;
char *this_line = NULL;
}
-/*
- * Implement HELP command.
- */
+// 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];
}
-/*
- *
- */
-void smtp_get_pass(void)
-{
+void smtp_get_pass(void) {
char password[SIZ];
memset(password, 0, sizeof(password));
}
-/*
- * Back end for PLAIN auth method (either inline or multistate)
- */
+// Back end for PLAIN auth method (either inline or multistate)
void smtp_try_plain(void) {
const char*decoded_authstring;
char ident[256] = "";
}
-/*
- * Attempt to perform authenticated SMTP
- */
+// Attempt to perform authenticated SMTP
void smtp_auth(void) {
char username_prompt[64];
char method[64];
}
-/*
- * 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.
- */
+// 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) {
- /*
- * Our entire SMTP state is discarded when a RSET command is issued,
- * but we need to preserve this one little piece of information, so
- * we save it for later.
- */
-
FlushStrBuf(SMTP->Cmd);
FlushStrBuf(SMTP->helo_node);
FlushStrBuf(SMTP->from);
SMTP->delivery_mode = 0;
SMTP->message_originated_locally = 0;
SMTP->is_msa = 0;
- /*
- * we must remember is_lmtp & is_unfiltered.
- */
-
- /*
- * It is somewhat ambiguous whether we want to log out when a RSET
- * command is issued. Here's the code to do it. It is commented out
- * because some clients (such as Pine) issue RSET commands before
- * each message, but still expect to be logged in.
- *
- * if (CC->logged_in) {
- * logout(CC);
- * }
- */
+ // 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.
- */
+// 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);
}
-/*
- * Implements the "MAIL FROM:" command
- */
+// Implements the "MAIL FROM:" command
void smtp_mail(void) {
char user[SIZ];
char node[SIZ];
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.
- */
+ // 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 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));
}
else if (SMTP->is_lmtp) {
- /* Bypass forgery checking for 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)
- */
+ // 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')",
}
-/*
- * Implements the "RCPT To:" command
- */
+// Implements the "RCPT To:" command
void smtp_rcpt(void) {
char message_to_spammer[SIZ];
struct recptypes *valid = NULL;
return;
}
- /* RBL check */
- if ( (!CC->logged_in) /* Don't RBL authenticated users */
- && (!SMTP->is_lmtp) ) { /* Don't RBL LMTP clients */
- if (CtdlGetConfigInt("c_rbl_at_greeting") == 0) { /* Don't RBL again if we already did it */
- 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);
- /* no need to free_recipients(valid), it's not allocated yet */
- 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(
- ChrPtr(SMTP->OneRcpt),
+ (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 (CC->logged_in) {
- if (CtdlCheckInternetMailPermission(&CC->user)==0) {
- 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...
+ && (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 ( (SMTP->message_originated_locally == 0)
- && (SMTP->is_lmtp == 0) ) {
- cprintf("551 <%s> - relaying denied\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));
}
-/*
- * Implements the DATA command
- */
+// Implements the DATA command
void smtp_data(void) {
StrBuf *body;
StrBuf *defbody;
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 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;
}
}
- /* Set the "envelope from" address */
+ // Set the "envelope from" address
CM_SetField(msg, eMessagePath, SKEY(SMTP->from));
- /* Set the "envelope to" address */
+ // Set the "envelope to" address
CM_SetField(msg, eenVelopeTo, SKEY(SMTP->recipients));
- /* Submit the message into the Citadel system. */
+ // Submit the message into the Citadel system.
valid = validate_recipients(
- ChrPtr(SMTP->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 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;
}
scan_errors = PerformMessageHooks(msg, valid, EVT_SMTPSCAN);
}
- if (scan_errors > 0) { /* We don't want this message! */
+ 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. */
+ else { // Ok, we'll accept this message.
msgnum = CtdlSubmitMsg(msg, valid, "");
if (msgnum > 0L) {
StrBufPrintf(SMTP->OneRcpt, "250 Message accepted.\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.
- */
+ // 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);
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).
- */
+ // 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->OneRcpt)
);
- /* Clean up */
+ // Clean up
CM_Free(msg);
free_recipients(valid);
- smtp_data_clear(); /* clear out the buffers now */
+ smtp_data_clear(); // clear out the buffers now
}
-/*
- * Implements the STARTTLS command
- */
+// Implements the STARTTLS command
void smtp_starttls(void) {
char ok_response[SIZ];
char nosup_response[SIZ];
}
-/*
- * Implements the NOOP (NO OPeration) command
- */
+// Implements the NOOP (NO OPeration) command
void smtp_noop(void) {
cprintf("250 NOOP\r\n");
}
-/*
- * Implements the QUIT command
- */
+// 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.
- */
+// Main command loop for SMTP server sessions.
void smtp_command_loop(void) {
static const ConstStr AuthPlainStr = {HKEY("AUTH PLAIN")};
projects / citadel.git / blobdiff