citadel/modules/smtp/smtp_util.c

   1 /*
   2  * This module is an SMTP and ESMTP implementation for the Citadel system.
   3  * It is compliant with all of the following:
   4  *
   5  * RFC  821 - Simple Mail Transfer Protocol
   6  * RFC  876 - Survey of SMTP Implementations
   7  * RFC 1047 - Duplicate messages and SMTP
   8  * RFC 1652 - 8 bit MIME
   9  * RFC 1869 - Extended Simple Mail Transfer Protocol
  10  * RFC 1870 - SMTP Service Extension for Message Size Declaration
  11  * RFC 2033 - Local Mail Transfer Protocol
  12  * RFC 2197 - SMTP Service Extension for Command Pipelining
  13  * RFC 2476 - Message Submission
  14  * RFC 2487 - SMTP Service Extension for Secure SMTP over TLS
  15  * RFC 2554 - SMTP Service Extension for Authentication
  16  * RFC 2821 - Simple Mail Transfer Protocol
  17  * RFC 2822 - Internet Message Format
  18  * RFC 2920 - SMTP Service Extension for Command Pipelining
  19  *
  20  * The VRFY and EXPN commands have been removed from this implementation
  21  * because nobody uses these commands anymore, except for spammers.
  22  *
  23  * Copyright (c) 1998-2017 by the citadel.org team
  24  *
  25  * This program is open source software; you can redistribute it and/or modify
  26  * it under the terms of the GNU General Public License version 3.
  27  *
  28  * This program is distributed in the hope that it will be useful,
  29  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  30  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  31  * GNU General Public License for more details.
  32  */
  33
  34 #include "sysdep.h"
  35 #include <stdlib.h>
  36 #include <unistd.h>
  37 #include <stdio.h>
  38 #include <termios.h>
  39 #include <fcntl.h>
  40 #include <signal.h>
  41 #include <pwd.h>
  42 #include <errno.h>
  43 #include <sys/types.h>
  44 #include <syslog.h>
  45
  46 #if TIME_WITH_SYS_TIME
  47 # include <sys/time.h>
  48 # include <time.h>
  49 #else
  50 # if HAVE_SYS_TIME_H
  51 #  include <sys/time.h>
  52 # else
  53 #  include <time.h>
  54 # endif
  55 #endif
  56
  57 #include <sys/wait.h>
  58 #include <ctype.h>
  59 #include <string.h>
  60 #include <limits.h>
  61 #include <sys/socket.h>
  62 #include <netinet/in.h>
  63 #include <arpa/inet.h>
  64 #include <libcitadel.h>
  65 #include "citadel.h"
  66 #include "server.h"
  67 #include "citserver.h"
  68 #include "support.h"
  69 #include "config.h"
  70 #include "control.h"
  71 #include "user_ops.h"
  72 #include "database.h"
  73 #include "msgbase.h"
  74 #include "internet_addressing.h"
  75 #include "genstamp.h"
  76 #include "domain.h"
  77 #include "clientsocket.h"
  78 #include "locate_host.h"
  79 #include "citadel_dirs.h"
  80
  81 #include "ctdl_module.h"
  82
  83 #include "smtp_util.h"
  84 #include "smtpqueue.h"
  85 #include "smtp_clienthandlers.h"
  86
  87 const char *smtp_get_Recipients(void)
  88 {
  89         citsmtp *sSMTP = SMTP;
  90
  91         if (sSMTP == NULL)
  92                 return NULL;
  93         else return ChrPtr(sSMTP->from);
  94 }
  95
  96
  97 /*
  98  * smtp_do_bounce() is caled by smtp_do_procmsg() to scan a set of delivery
  99  * instructions for "5" codes (permanent fatal errors) and produce/deliver
 100  * a "bounce" message (delivery status notification).
 101  */
 102 void smtp_do_bounce(char *instr, StrBuf *OMsgTxt)
 103 {
 104         int i;
 105         int lines;
 106         int status;
 107         char buf[1024];
 108         char key[1024];
 109         char addr[1024];
 110         char dsn[1024];
 111         char bounceto[1024];
 112         StrBuf *boundary;
 113         int num_bounces = 0;
 114         int bounce_this = 0;
 115         time_t submitted = 0L;
 116         struct CtdlMessage *bmsg = NULL;
 117         int give_up = 0;
 118         recptypes *valid;
 119         int successful_bounce = 0;
 120         static int seq = 0;
 121         StrBuf *BounceMB;
 122         long omsgid = (-1);
 123
 124         syslog(LOG_DEBUG, "smtp_do_bounce() called");
 125         strcpy(bounceto, "");
 126         boundary = NewStrBufPlain(HKEY("=_Citadel_Multipart_"));
 127
 128         StrBufAppendPrintf(boundary, "%s_%04x%04x", CtdlGetConfigStr("c_fqdn"), getpid(), ++seq);
 129
 130         lines = num_tokens(instr, '\n');
 131
 132         /* See if it's time to give up on delivery of this message */
 133         for (i=0; i<lines; ++i) {
 134                 extract_token(buf, instr, i, '\n', sizeof buf);
 135                 extract_token(key, buf, 0, '|', sizeof key);
 136                 extract_token(addr, buf, 1, '|', sizeof addr);
 137                 if (!strcasecmp(key, "submitted")) {
 138                         submitted = atol(addr);
 139                 }
 140         }
 141
 142         if ( (time(NULL) - submitted) > SMTP_GIVE_UP ) {
 143                 give_up = 1;
 144         }
 145
 146         /* Start building our bounce message */
 147
 148         bmsg = (struct CtdlMessage *) malloc(sizeof(struct CtdlMessage));
 149         if (bmsg == NULL) return;
 150         memset(bmsg, 0, sizeof(struct CtdlMessage));
 151         BounceMB = NewStrBufPlain(NULL, 1024);
 152
 153         bmsg->cm_magic = CTDLMESSAGE_MAGIC;
 154         bmsg->cm_anon_type = MES_NORMAL;
 155         bmsg->cm_format_type = FMT_RFC822;
 156         CM_SetField(bmsg, eAuthor, HKEY("Citadel"));
 157         CM_SetField(bmsg, eOriginalRoom, HKEY(MAILROOM));
 158         CM_SetField(bmsg, eNodeName, CtdlGetConfigStr("c_nodename"), strlen(CtdlGetConfigStr("c_nodename")));
 159         CM_SetField(bmsg, eMsgSubject, HKEY("Delivery Status Notification (Failure)"));
 160         StrBufAppendBufPlain(BounceMB, HKEY("Content-type: multipart/mixed; boundary=\""), 0);
 161         StrBufAppendBuf(BounceMB, boundary, 0);
 162         StrBufAppendBufPlain(BounceMB, HKEY("\"\r\n"), 0);
 163         StrBufAppendBufPlain(BounceMB, HKEY("MIME-Version: 1.0\r\n"), 0);
 164         StrBufAppendBufPlain(BounceMB, HKEY("X-Mailer: " CITADEL "\r\n"), 0);
 165
 166         StrBufAppendBufPlain(
 167                 BounceMB,
 168                 HKEY("\r\nThis is a multipart message in MIME format."
 169                      "\r\n\r\n"), 0);
 170
 171         StrBufAppendBufPlain(BounceMB, HKEY("--"), 0);
 172         StrBufAppendBuf(BounceMB, boundary, 0);
 173         StrBufAppendBufPlain(BounceMB, HKEY("\r\n"), 0);
 174         StrBufAppendBufPlain(BounceMB,
 175                              HKEY("Content-type: text/plain\r\n\r\n"), 0);
 176
 177         if (give_up)
 178         {
 179                 StrBufAppendBufPlain(
 180                         BounceMB,
 181                         HKEY("A message you sent could not be delivered "
 182                              "to some or all of its recipients\ndue to "
 183                              "prolonged unavailability of its destination(s).\n"
 184                              "Giving up on the following addresses:\n\n"), 0);
 185         }
 186         else
 187         {
 188                 StrBufAppendBufPlain(
 189                         BounceMB,
 190                         HKEY("A message you sent could not be delivered "
 191                              "to some or all of its recipients.\n"
 192                              "The following addresses were undeliverable:\n\n"
 193                                 ), 0);
 194         }
 195
 196         /*
 197          * Now go through the instructions checking for stuff.
 198          */
 199         for (i=0; i<lines; ++i) {
 200                 long addrlen;
 201                 long dsnlen;
 202                 extract_token(buf, instr, i, '\n', sizeof buf);
 203                 extract_token(key, buf, 0, '|', sizeof key);
 204                 addrlen = extract_token(addr, buf, 1, '|', sizeof addr);
 205                 status = extract_int(buf, 2);
 206                 dsnlen = extract_token(dsn, buf, 3, '|', sizeof dsn);
 207                 bounce_this = 0;
 208
 209                 syslog(LOG_DEBUG, "key=<%s> addr=<%s> status=%d dsn=<%s>", key, addr, status, dsn);
 210
 211                 if (!strcasecmp(key, "bounceto")) {
 212                         strcpy(bounceto, addr);
 213                 }
 214
 215                 if (!strcasecmp(key, "msgid")) {
 216                         omsgid = atol(addr);
 217                 }
 218
 219                 if (!strcasecmp(key, "remote")) {
 220                         if (status == 5) bounce_this = 1;
 221                         if (give_up) bounce_this = 1;
 222                 }
 223
 224                 if (bounce_this) {
 225                         ++num_bounces;
 226
 227                         StrBufAppendBufPlain(BounceMB, addr, addrlen, 0);
 228                         StrBufAppendBufPlain(BounceMB, HKEY(": "), 0);
 229                         StrBufAppendBufPlain(BounceMB, dsn, dsnlen, 0);
 230                         StrBufAppendBufPlain(BounceMB, HKEY("\r\n"), 0);
 231
 232                         remove_token(instr, i, '\n');
 233                         --i;
 234                         --lines;
 235                 }
 236         }
 237
 238         /* Attach the original message */
 239         if (omsgid >= 0) {
 240                 StrBufAppendBufPlain(BounceMB, HKEY("--"), 0);
 241                 StrBufAppendBuf(BounceMB, boundary, 0);
 242                 StrBufAppendBufPlain(BounceMB, HKEY("\r\n"), 0);
 243
 244                 StrBufAppendBufPlain(
 245                         BounceMB,
 246                         HKEY("Content-type: message/rfc822\r\n"), 0);
 247
 248                 StrBufAppendBufPlain(
 249                         BounceMB,
 250                         HKEY("Content-Transfer-Encoding: 7bit\r\n"), 0);
 251
 252                 StrBufAppendBufPlain(
 253                         BounceMB,
 254                         HKEY("Content-Disposition: inline\r\n"), 0);
 255
 256                 StrBufAppendBufPlain(BounceMB, HKEY("\r\n"), 0);
 257
 258                 if (OMsgTxt == NULL) {
 259                         CC->redirect_buffer = NewStrBufPlain(NULL, SIZ);
 260                         CtdlOutputMsg(omsgid,
 261                                       MT_RFC822,
 262                                       HEADERS_ALL,
 263                                       0, 1, NULL, 0,
 264                                       NULL, NULL, NULL);
 265
 266                         StrBufAppendBuf(BounceMB, CC->redirect_buffer, 0);
 267                         FreeStrBuf(&CC->redirect_buffer);
 268                 }
 269                 else {
 270                         StrBufAppendBuf(BounceMB, OMsgTxt, 0);
 271                 }
 272         }
 273
 274         /* Close the multipart MIME scope */
 275         StrBufAppendBufPlain(BounceMB, HKEY("--"), 0);
 276         StrBufAppendBuf(BounceMB, boundary, 0);
 277         StrBufAppendBufPlain(BounceMB, HKEY("--\r\n"), 0);
 278         CM_SetAsFieldSB(bmsg, eMesageText, &BounceMB);
 279
 280         /* Deliver the bounce if there's anything worth mentioning */
 281         syslog(LOG_DEBUG, "num_bounces = %d", num_bounces);
 282         if (num_bounces > 0) {
 283
 284                 /* First try the user who sent the message */
 285                 if (IsEmptyStr(bounceto)) {
 286                         syslog(LOG_ERR, "No bounce address specified");
 287                 }
 288                 else {
 289                         syslog(LOG_DEBUG, "bounce to user <%s>", bounceto);
 290                 }
 291                 /* Can we deliver the bounce to the original sender? */
 292                 valid = validate_recipients(bounceto,
 293                                             smtp_get_Recipients (),
 294                                             0);
 295                 if (valid != NULL) {
 296                         if (valid->num_error == 0) {
 297                                 CtdlSubmitMsg(bmsg, valid, "", QP_EADDR);
 298                                 successful_bounce = 1;
 299                         }
 300                 }
 301
 302                 /* If not, post it in the Aide> room */
 303                 if (successful_bounce == 0) {
 304                         CtdlSubmitMsg(bmsg, NULL, CtdlGetConfigStr("c_aideroom"), QP_EADDR);
 305                 }
 306
 307                 /* Free up the memory we used */
 308                 if (valid != NULL) {
 309                         free_recipients(valid);
 310                 }
 311         }
 312         FreeStrBuf(&boundary);
 313         CM_Free(bmsg);
 314         syslog(LOG_DEBUG, "Done processing bounces");
 315 }