1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) Wolfgang Breyha 2005 - 2019
6 * Vienna University Computer Center
8 * See the file NOTICE for conditions of use and distribution.
10 * Copyright (c) The Exim Maintainers 2015 - 2022
11 * SPDX-License-Identifier: GPL-2.0-or-later
14 /* Code for calling dccifd. Called from acl.c. */
17 #ifdef EXPERIMENTAL_DCC
18 #ifndef WITH_CONTENT_SCAN
19 # error EXPERIMENTAL_DCC requires WITH_CONTENT_SCAN
25 #define DCC_HEADER_LIMIT 120
30 /* This function takes a file descriptor and a buffer as input and
31 returns either 0 for success or errno in case of error. */
33 static int flushbuffer
34 (int socket, gstring *buffer)
38 rsp = write(socket, buffer->s, buffer->ptr);
40 debug_printf("DCC: flushbuffer(): Result of the write() = %d\n", rsp);
44 debug_printf("DCC: flushbuffer(): Error writing buffer to socket: %s\n", strerror(errno));
48 debug_printf("DCC: flushbuffer(): Wrote buffer to socket:\n%.*s\n", buffer->ptr, buffer->s);
53 dcc_process(uschar **listptr)
56 const uschar *list = *listptr;
58 uschar *dcc_default_ip_option = US"127.0.0.1";
59 uschar *dcc_helo_option = US"localhost";
60 uschar *xtra_hdrs = NULL;
61 uschar *override_client_ip = NULL;
64 int dcc_resplen, retval, sockfd, resp;
66 struct sockaddr_un serv_addr;
67 struct sockaddr_in serv_addr_in;
68 struct hostent *ipaddress;
70 uschar sockip[40], client_ip[40];
73 uschar *dcc_return_text = US"''";
74 struct header_line *mail_headers;
75 uschar *dcc_acl_options;
76 gstring *dcc_xtra_hdrs;
77 gstring *dcc_header_str;
80 if ((dcc_acl_options = string_nextinlist(&list, &sep, NULL, 0)))
82 /* parse 1st option */
83 if ( strcmpic(dcc_acl_options, US"false") == 0
84 || Ustrcmp(dcc_acl_options, "0") == 0)
85 return FAIL; /* explicitly no matching */
88 return FAIL; /* empty means "don't match anything" */
92 /* if we scanned this message last time, just return */
96 /* open the spooled body */
97 for (int i = 0; i < 2; i++)
99 uschar message_subdir[2];
100 set_subdir_str(message_subdir, message_id, i);
101 if ((data_file = Ufopen(
102 spool_fname(US"input", message_subdir, message_id, US"-D"), "rb")))
108 /* error while spooling */
109 log_write(0, LOG_MAIN|LOG_PANIC,
110 "DCC: error while opening spool file");
114 /* Initialize the variables */
116 bzero(sockip,sizeof(sockip));
119 if (dccifd_address[0] == '/')
120 Ustrncpy(sockpath, dccifd_address, sizeof(sockpath));
122 if( sscanf(CS dccifd_address, "%s %u", sockip, &portnr) != 2)
124 log_write(0, LOG_MAIN,
125 "DCC: warning - invalid dccifd address: '%s'", dccifd_address);
126 (void)fclose(data_file);
131 /* dcc_headers is what we send as dccifd options - see man dccifd */
132 /* We don't support any other option than 'header' so just copy that */
133 dcc_headers = string_cat(NULL, dccifd_options);
134 /* if $acl_m_dcc_override_client_ip is set use it */
135 if (((override_client_ip = expand_string(US"$acl_m_dcc_override_client_ip")) != NULL) &&
136 (override_client_ip[0] != '\0'))
138 Ustrncpy(client_ip, override_client_ip, sizeof(client_ip)-1);
140 debug_printf("DCC: Client IP (overridden): %s\n", client_ip);
142 else if(sender_host_address)
144 /* else if $sender_host_address is available use that? */
145 Ustrncpy(client_ip, sender_host_address, sizeof(client_ip)-1);
147 debug_printf("DCC: Client IP (sender_host_address): %s\n", client_ip);
151 /* sender_host_address is NULL which means it comes from localhost */
152 Ustrncpy(client_ip, dcc_default_ip_option, sizeof(client_ip)-1);
154 debug_printf("DCC: Client IP (default): %s\n", client_ip);
156 /* build options block */
157 dcc_headers = string_append(dcc_headers, 5, US"\n", client_ip, US"\nHELO ", dcc_helo_option, US"\n");
159 /* initialize the other variables */
160 mail_headers = header_list;
161 /* we set the default return value to DEFER */
164 /* send a null return path as "<>". */
165 dcc_headers = string_cat (dcc_headers, *sender_address ? sender_address : US"<>");
166 dcc_headers = string_catn(dcc_headers, US"\n", 1);
168 /**************************************
169 * Now creating the socket connection *
170 **************************************/
172 /* If sockip contains an ip, we use a tcp socket, otherwise a UNIX socket */
173 if(Ustrcmp(sockip, ""))
175 ipaddress = gethostbyname(CS sockip);
176 bzero(CS &serv_addr_in, sizeof(serv_addr_in));
177 serv_addr_in.sin_family = AF_INET;
178 bcopy(CS ipaddress->h_addr, CS &serv_addr_in.sin_addr.s_addr, ipaddress->h_length);
179 serv_addr_in.sin_port = htons(portnr);
180 if ((sockfd = socket(AF_INET, SOCK_STREAM,0)) < 0)
183 debug_printf("DCC: Creating TCP socket connection failed: %s\n", strerror(errno));
184 log_write(0,LOG_PANIC,"DCC: Creating TCP socket connection failed: %s\n", strerror(errno));
185 /* if we cannot create the socket, defer the mail */
186 (void)fclose(data_file);
189 /* Now connecting the socket (INET) */
190 if (connect(sockfd, (struct sockaddr *)&serv_addr_in, sizeof(serv_addr_in)) < 0)
193 debug_printf("DCC: Connecting to TCP socket failed: %s\n", strerror(errno));
194 log_write(0,LOG_PANIC,"DCC: Connecting to TCP socket failed: %s\n", strerror(errno));
195 /* if we cannot contact the socket, defer the mail */
196 (void)fclose(data_file);
202 /* connecting to the dccifd UNIX socket */
203 bzero(&serv_addr, sizeof(serv_addr));
204 serv_addr.sun_family = AF_UNIX;
205 Ustrncpy(US serv_addr.sun_path, sockpath, sizeof(serv_addr.sun_path));
206 if ((sockfd = socket(AF_UNIX, SOCK_STREAM,0)) < 0)
209 debug_printf("DCC: Creating UNIX socket connection failed: %s\n", strerror(errno));
210 log_write(0,LOG_PANIC,"DCC: Creating UNIX socket connection failed: %s\n", strerror(errno));
211 /* if we cannot create the socket, defer the mail */
212 (void)fclose(data_file);
215 /* Now connecting the socket (UNIX) */
216 if (connect(sockfd, (struct sockaddr *) &serv_addr, sizeof(serv_addr)) < 0)
219 debug_printf("DCC: Connecting to UNIX socket failed: %s\n", strerror(errno));
220 log_write(0,LOG_PANIC,"DCC: Connecting to UNIX socket failed: %s\n", strerror(errno));
221 /* if we cannot contact the socket, defer the mail */
222 (void)fclose(data_file);
226 /* the socket is open, now send the options to dccifd*/
228 debug_printf("DCC: -----------------------------------\nDCC: Socket opened; now sending input\n"
229 "DCC: -----------------------------------\n");
231 /* let's send each of the recipients to dccifd */
232 for (int i = 0; i < recipients_count; i++)
235 debug_printf("DCC: recipient = %s\n",recipients_list[i].address);
236 dcc_headers = string_append(dcc_headers, 2, recipients_list[i].address, "\n");
238 /* send a blank line between options and message */
239 dcc_headers = string_catn(dcc_headers, US"\n", 1);
241 /* Now we send the input buffer */
243 debug_printf("DCC: ***********************************\nDCC: Sending options:\n%Y"
244 "DCC: ***********************************\n", dcc_headers);
245 if (flushbuffer(sockfd, dcc_headers) != 0)
247 (void)fclose(data_file);
251 /* now send the message */
252 /* First send the headers */
254 debug_printf("DCC: ***********************************\nDCC: Sending headers:\n");
255 sendbuf = string_get(8192);
256 sendbuf = string_catn(sendbuf, mail_headers->text, mail_headers->slen);
257 while((mail_headers=mail_headers->next))
258 sendbuf = string_catn(sendbuf, mail_headers->text, mail_headers->slen);
260 /* a blank line separates header from body */
261 sendbuf = string_catn(sendbuf, US"\r\n", 2);
262 gstring_release_unused(sendbuf);
264 debug_printf("%YDCC: ***********************************\n", sendbuf);
265 if (flushbuffer(sockfd, sendbuf) != 0)
267 (void)fclose(data_file);
271 /* now send the body */
273 debug_printf("DCC: ***********************************\nDCC: Writing body:\n");
274 (void)fseek(data_file, spool_data_start_offset(message_id), SEEK_SET);
276 gstring filebuf = { .size = big_buffer_size, .ptr = 0, .s = big_buffer };
278 while((filebuf.ptr = fread(filebuf.s, 1, filebuf.size, data_file)) > 0)
279 if (flushbuffer(sockfd, &filebuf) != 0)
281 (void)fclose(data_file);
285 debug_printf("DCC: ***********************************\n");
287 /* shutdown() the socket */
288 if(shutdown(sockfd, SHUT_WR) < 0)
291 debug_printf("DCC: Couldn't shutdown socket: %s\n", strerror(errno));
292 log_write(0,LOG_MAIN,"DCC: Couldn't shutdown socket: %s\n", strerror(errno));
293 /* If there is a problem with the shutdown()
295 (void)fclose(data_file);
299 debug_printf("DCC: Input sent.\n"
300 "DCC: +++++++++++++++++++++++++++++++++++\n"
301 "DCC: Now receiving output from server\n"
302 "DCC: -----------------------------------\n");
304 /********************************
305 * receiving output from dccifd *
306 ********************************/
308 /******************************************************************
309 * We should get 3 lines: *
310 * 1/ First line is overall result: either 'A' for Accept, *
311 * 'R' for Reject, 'S' for accept Some recipients or *
312 * 'T' for a Temporary error. *
313 * 2/ Second line contains the list of Accepted/Rejected *
314 * recipients in the form AARRA (A = accepted, R = rejected). *
315 * 3/ Third line contains the X-DCC header. *
316 ******************************************************************/
318 int line = 1; /* we start at the first line of the output */
321 dcc_header_str = string_get(DCC_HEADER_LIMIT + 2);
322 /* Let's read from the socket until there's nothing left to read */
323 while((dcc_resplen = read(sockfd, big_buffer, big_buffer_size-1)) > 0)
325 /* fail on read error */
329 debug_printf("DCC: Error reading from socket: %s\n", strerror(errno));
330 (void)fclose(data_file);
333 /* make the answer 0-terminated. only needed for debug_printf */
335 debug_printf("DCC: Length of the output buffer is: %d\nDCC: Output buffer is:\n"
336 "DCC: -----------------------------------\n%.*s\n"
337 "DCC: -----------------------------------\n", dcc_resplen, dcc_resplen, big_buffer);
339 /* Now let's read each character and see what we've got */
340 for(bufoffset = 0; bufoffset < dcc_resplen && line <= 2; bufoffset++)
342 /* First check if we reached the end of the line and
343 then increment the line counter */
344 if(big_buffer[bufoffset] == '\n')
348 /* The first character of the first line is the overall response. If
349 there's another character on that line it is not correct. */
354 /* Now get the value and set the return value accordingly */
355 switch (big_buffer[bufoffset])
359 debug_printf("DCC: Overall result = A\treturning OK\n");
360 dcc_return_text = US"Mail accepted by DCC";
366 debug_printf("DCC: Overall result = R\treturning FAIL\n");
367 dcc_return_text = US"Rejected by DCC";
371 log_write(0, LOG_MAIN, "H=%s [%s] F=<%s>: rejected by DCC",
372 sender_host_name, sender_host_address, sender_address);
374 log_write(0, LOG_MAIN, "H=[%s] F=<%s>: rejected by DCC",
375 sender_host_address, sender_address);
379 debug_printf("DCC: Overall result = S\treturning OK\n");
380 dcc_return_text = US"Not all recipients accepted by DCC";
381 /* Since we're in an ACL we want a global result so we accept for all */
387 debug_printf("DCC: Overall result = G\treturning FAIL\n");
388 dcc_return_text = US"Greylisted by DCC";
394 debug_printf("DCC: Overall result = T\treturning DEFER\n");
395 dcc_return_text = US"Temporary error with DCC";
398 log_write(0,LOG_MAIN,"Temporary error with DCC: %s\n", big_buffer);
402 debug_printf("DCC: Overall result = something else\treturning DEFER\n");
403 dcc_return_text = US"Unknown DCC response";
406 log_write(0,LOG_MAIN,"Unknown DCC response: %s\n", big_buffer);
412 /* We're on the first line but not on the first character,
413 * there must be something wrong. */
414 DEBUG(D_acl) debug_printf("DCC: Line = %d but bufoffset = %d != 0"
415 " character is %c - This is wrong!\n", line, bufoffset, big_buffer[bufoffset]);
416 log_write(0,LOG_MAIN,"Wrong header from DCC, output is %s\n", big_buffer);
421 /* On the second line we get a list of answers for each recipient. We
422 don't care about it because we're in an acl and take the global result. */
428 /* The third and following lines are the X-DCC header, so we store it in
429 dcc_header_str up to our limit. */
430 /* check if buffer contains the end of the header .."\n\n" and truncate it */
431 if ((big_buffer[dcc_resplen-1] == '\n') &&
432 (big_buffer[dcc_resplen-2] == '\n'))
434 dcc_resplen -= bufoffset;
435 if (dcc_header_str->ptr + dcc_resplen > DCC_HEADER_LIMIT)
437 dcc_resplen = DCC_HEADER_LIMIT - dcc_header_str->ptr;
438 DEBUG(D_acl) debug_printf("DCC: We got more output than we can store"
439 "in the X-DCC header. Truncating at 120 characters.\n");
441 dcc_header_str = string_catn(dcc_header_str, &big_buffer[bufoffset], dcc_resplen);
444 /* We have read everything from the socket. make sure the header ends with "\n" */
445 dcc_header_str = string_catn(dcc_header_str, US"\n", 1);
447 (void) string_from_gstring(dcc_header_str);
448 /* Now let's sum up what we've got. */
450 debug_printf("\nDCC: --------------------------\nDCC: Overall result = %d\n"
451 "DCC: X-DCC header: %YReturn message: %s\nDCC: dcc_result: %s\n",
452 retval, dcc_header_str, dcc_return_text, dcc_result);
454 /* We only add the X-DCC header if it starts with X-DCC */
455 if(!(Ustrncmp(dcc_header_str->s, "X-DCC", 5)))
457 dcc_header = string_from_gstring(dcc_header_str);
458 if(dcc_direct_add_header)
460 header_add(' ' , "%s", dcc_header);
461 /* since the MIME ACL already writes the .eml file to disk without DCC Header we've to erase it */
467 debug_printf("DCC: Wrong format of the X-DCC header: %Y\n", dcc_header_str);
469 /* check if we should add additional headers passed in acl_m_dcc_add_header */
470 if (dcc_direct_add_header)
472 if (((xtra_hdrs = expand_string(US"$acl_m_dcc_add_header")) != NULL) && (xtra_hdrs[0] != '\0'))
474 dcc_xtra_hdrs = string_cat(NULL, xtra_hdrs);
475 if (dcc_xtra_hdrs->s[dcc_xtra_hdrs->ptr - 1] != '\n')
476 dcc_xtra_hdrs = string_catn(dcc_xtra_hdrs, US"\n", 1);
477 header_add(' ', "%s", string_from_gstring(dcc_xtra_hdrs));
479 debug_printf("DCC: adding additional headers in $acl_m_dcc_add_header: %Y", dcc_xtra_hdrs);
484 /* Now return to exim main process */
486 debug_printf("DCC: Before returning to exim main process:\nDCC: return_text = %s - retval = %d\n"
487 "DCC: dcc_result = %s\n", dcc_return_text, retval, dcc_result);
489 (void)fclose(data_file);