2 * Routines for SMTP packet disassembly
4 * $Id: packet-smtp.c,v 1.32 2002/08/28 21:00:34 jmayer Exp $
6 * Copyright (c) 2000 by Richard Sharpe <rsharpe@ns.aus.com>
8 * Ethereal - Network traffic analyzer
9 * By Gerald Combs <gerald@ethereal.com>
10 * Copyright 1999 Gerald Combs
12 * This program is free software; you can redistribute it and/or
13 * modify it under the terms of the GNU General Public License
14 * as published by the Free Software Foundation; either version 2
15 * of the License, or (at your option) any later version.
17 * This program is distributed in the hope that it will be useful,
18 * but WITHOUT ANY WARRANTY; without even the implied warranty of
19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20 * GNU General Public License for more details.
22 * You should have received a copy of the GNU General Public License
23 * along with this program; if not, write to the Free Software
24 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
37 #include <epan/packet.h>
38 #include <epan/conversation.h>
39 #include <epan/resolv.h>
41 #include <epan/strutil.h>
43 #define TCP_PORT_SMTP 25
45 void proto_reg_handoff_smtp(void);
47 static int proto_smtp = -1;
49 static int hf_smtp_req = -1;
50 static int hf_smtp_rsp = -1;
51 static int hf_smtp_req_command = -1;
52 static int hf_smtp_req_parameter = -1;
53 static int hf_smtp_rsp_code = -1;
54 static int hf_smtp_rsp_parameter = -1;
56 static int ett_smtp = -1;
58 static int global_smtp_tcp_port = TCP_PORT_SMTP;
60 /* desegmentation of SMTP command and response lines */
61 static gboolean smtp_desegment = TRUE;
64 * A CMD is an SMTP command, MESSAGE is the message portion, and EOM is the
65 * last part of a message
68 #define SMTP_PDU_CMD 0
69 #define SMTP_PDU_MESSAGE 1
70 #define SMTP_PDU_EOM 2
72 struct smtp_proto_data {
76 static int smtp_packet_init_count = 100;
79 * State information stored with a conversation.
81 struct smtp_request_val {
82 gboolean reading_data; /* Reading message data, not commands */
83 guint16 crlf_seen; /* Have we seen a CRLF on the end of a packet */
86 static GMemChunk *smtp_request_vals = NULL;
87 static GMemChunk *smtp_packet_infos = NULL;
90 smtp_init_protocol(void)
92 if (smtp_request_vals)
93 g_mem_chunk_destroy(smtp_request_vals);
94 if (smtp_packet_infos)
95 g_mem_chunk_destroy(smtp_packet_infos);
97 smtp_request_vals = g_mem_chunk_new("smtp_request_vals",
98 sizeof(struct smtp_request_val),
99 smtp_packet_init_count * sizeof(struct smtp_request_val), G_ALLOC_AND_FREE);
100 smtp_packet_infos = g_mem_chunk_new("smtp_packet_infos",
101 sizeof(struct smtp_proto_data),
102 smtp_packet_init_count * sizeof(struct smtp_proto_data), G_ALLOC_AND_FREE);
107 dissect_smtp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
109 struct smtp_proto_data *frame_data;
110 proto_tree *smtp_tree;
114 conversation_t *conversation;
115 struct smtp_request_val *request_val;
119 gboolean eom_seen = FALSE;
121 gboolean is_continuation_line;
124 /* As there is no guarantee that we will only see frames in the
125 * the SMTP conversation once, and that we will see them in
126 * order - in Ethereal, the user could randomly click on frames
127 * in the conversation in any order in which they choose - we
128 * have to store information with each frame indicating whether
129 * it contains commands or data or an EOM indication.
131 * XXX - what about frames that contain *both*? TCP is a
132 * byte-stream protocol, and there are no guarantees that
133 * TCP segment boundaries will correspond to SMTP commands
134 * or EOM indications.
136 * We only need that for the client->server stream; responses
137 * are easy to manage.
139 * If we have per frame data, use that, else, we must be on the first
140 * pass, so we figure it out on the first pass.
143 /* Find out what conversation this packet is part of ... but only
144 * if we have no information on this packet, so find the per-frame
148 /* SMTP messages have a simple format ... */
150 request = pinfo -> destport == pinfo -> match_port;
153 * Get the first line from the buffer.
155 * Note that "tvb_find_line_end()" will, if it doesn't return
156 * -1, return a value that is not longer than what's in the buffer,
157 * and "tvb_find_line_end()" will always return a value that is not
158 * longer than what's in the buffer, so the "tvb_get_ptr()" call
159 * won't throw an exception.
161 linelen = tvb_find_line_end(tvb, offset, -1, &next_offset,
162 smtp_desegment && pinfo->can_desegment);
165 * We didn't find a line ending, and we're doing desegmentation;
166 * tell the TCP dissector where the data for this message starts
167 * in the data it handed us, and tell it we need one more byte
168 * (we may need more, but we'll try again if what we get next
169 * isn't enough), and return.
171 pinfo->desegment_offset = offset;
172 pinfo->desegment_len = 1;
175 line = tvb_get_ptr(tvb, offset, linelen);
177 frame_data = p_get_proto_data(pinfo->fd, proto_smtp);
181 conversation = find_conversation(&pinfo->src, &pinfo->dst, pinfo->ptype,
182 pinfo->srcport, pinfo->destport, 0);
183 if (conversation == NULL) { /* No conversation, create one */
184 conversation = conversation_new(&pinfo->src, &pinfo->dst, pinfo->ptype,
185 pinfo->srcport, pinfo->destport, 0);
190 * Is there a request structure attached to this conversation?
192 request_val = conversation_get_proto_data(conversation, proto_smtp);
197 * No - create one and attach it.
199 request_val = g_mem_chunk_alloc(smtp_request_vals);
200 request_val->reading_data = FALSE;
201 request_val->crlf_seen = 0;
203 conversation_add_proto_data(conversation, proto_smtp, request_val);
208 * Check whether or not this packet is an end of message packet
209 * We should look for CRLF.CRLF and they may be split.
210 * We have to keep in mind that we may see what we want on
211 * two passes through here ...
214 if (request_val->reading_data) {
217 * The order of these is important ... We want to avoid
218 * cases where there is a CRLF at the end of a packet and a
219 * .CRLF at the begining of the same packet.
222 if ((request_val->crlf_seen && tvb_strneql(tvb, offset, ".\r\n", 3) == 0) ||
223 tvb_strneql(tvb, offset, "\r\n.\r\n", 5) == 0) {
229 if (tvb_strneql(tvb, offset + tvb_length_remaining(tvb, offset) - 2, "\r\n", 2) == 0) {
231 request_val->crlf_seen = 1;
236 request_val->crlf_seen = 0;
242 * OK, Check if we have seen a DATA request. We do it here for
243 * simplicity, but we have to be careful below.
248 frame_data = g_mem_chunk_alloc(smtp_packet_infos);
250 if (request_val->reading_data) {
252 * This is message data.
254 if (eom_seen) { /* Seen the EOM */
257 * Everything that comes after it is commands.
259 * XXX - what if the EOM isn't at the beginning of
260 * the TCP segment? It can occur anywhere....
262 frame_data->pdu_type = SMTP_PDU_EOM;
263 request_val->reading_data = FALSE;
266 * Message data with no EOM.
268 frame_data->pdu_type = SMTP_PDU_MESSAGE;
272 * This is commands - unless the capture started in the
273 * middle of a session, and we're in the middle of data.
274 * To quote RFC 821, "Command codes are four alphabetic
275 * characters"; if we don't see four alphabetic characters
276 * and, if there's anything else in the line, a space, we
277 * assume it's not a command.
278 * (We treat only A-Z and a-z as alphabetic.)
280 #define ISALPHA(c) (((c) >= 'A' && (c) <= 'Z') || \
281 ((c) >= 'a' && (c) <= 'z'))
282 if (linelen >= 4 && ISALPHA(line[0]) && ISALPHA(line[1]) &&
283 ISALPHA(line[2]) && ISALPHA(line[3]) &&
284 (linelen == 4 || line[4] == ' ')) {
285 if (strncasecmp(line, "DATA", 4) == 0) {
289 * This is a command, but everything that comes after it,
290 * until an EOM, is data.
292 frame_data->pdu_type = SMTP_PDU_CMD;
293 request_val->reading_data = TRUE;
300 frame_data->pdu_type = SMTP_PDU_CMD;
306 * Assume it's message data.
309 frame_data->pdu_type = SMTP_PDU_MESSAGE;
315 p_add_proto_data(pinfo->fd, proto_smtp, frame_data);
321 * From here, we simply add items to the tree and info to the info
325 if (check_col(pinfo->cinfo, COL_PROTOCOL))
326 col_set_str(pinfo->cinfo, COL_PROTOCOL, "SMTP");
328 if (check_col(pinfo->cinfo, COL_INFO)) { /* Add the appropriate type here */
331 * If it is a request, we have to look things up, otherwise, just
332 * display the right things
337 /* We must have frame_data here ... */
339 switch (frame_data->pdu_type) {
340 case SMTP_PDU_MESSAGE:
342 col_set_str(pinfo->cinfo, COL_INFO, "Message Body");
347 col_add_fstr(pinfo->cinfo, COL_INFO, "EOM: %s",
348 format_text(line, linelen));
353 col_add_fstr(pinfo->cinfo, COL_INFO, "Command: %s",
354 format_text(line, linelen));
362 col_add_fstr(pinfo->cinfo, COL_INFO, "Response: %s",
363 format_text(line, linelen));
368 if (tree) { /* Build the tree info ... */
370 ti = proto_tree_add_item(tree, proto_smtp, tvb, offset, -1, FALSE);
371 smtp_tree = proto_item_add_subtree(ti, ett_smtp);
375 * Check out whether or not we can see a command in there ...
376 * What we are looking for is not data_seen and the word DATA
379 * We will see DATA and request_val->data_seen when we process the
380 * tree view after we have seen a DATA packet when processing
381 * the packet list pane.
383 * On the first pass, we will not have any info on the packets
384 * On second and subsequent passes, we will.
387 switch (frame_data->pdu_type) {
389 case SMTP_PDU_MESSAGE:
393 * Put its lines into the protocol tree, a line at a time.
395 while (tvb_offset_exists(tvb, offset)) {
398 * Find the end of the line.
400 tvb_find_line_end(tvb, offset, -1, &next_offset, FALSE);
405 proto_tree_add_text(smtp_tree, tvb, offset, next_offset - offset,
407 tvb_format_text(tvb, offset, next_offset - offset));
410 * Step to the next line.
412 offset = next_offset;
421 * End-of-message-body indicator.
423 * XXX - what about stuff after the first line?
424 * Unlikely, as the client should wait for a response to the
425 * DATA command this terminates before sending another
426 * request, but we should probably handle it.
428 proto_tree_add_text(smtp_tree, tvb, offset, linelen,
429 "EOM: %s", format_text(line, linelen));
438 * XXX - what about stuff after the first line?
439 * Unlikely, as the client should wait for a response to the
440 * previous command before sending another request, but we
441 * should probably handle it.
447 proto_tree_add_boolean_hidden(smtp_tree, hf_smtp_req, tvb,
449 proto_tree_add_item(smtp_tree, hf_smtp_req_command, tvb,
450 offset, cmdlen, FALSE);
452 proto_tree_add_item(smtp_tree, hf_smtp_req_parameter, tvb,
453 offset + 5, linelen - 5, FALSE);
462 * Process the response, a line at a time, until we hit a line
463 * that doesn't have a continuation indication on it.
465 proto_tree_add_boolean_hidden(smtp_tree, hf_smtp_rsp, tvb,
468 while (tvb_offset_exists(tvb, offset)) {
471 * Find the end of the line.
473 linelen = tvb_find_line_end(tvb, offset, -1, &next_offset, FALSE);
476 * Is it a continuation line?
478 is_continuation_line =
479 (linelen >= 4 && tvb_get_guint8(tvb, offset + 3) == '-');
482 * Put it into the protocol tree.
484 line = tvb_get_ptr(tvb, offset, linelen);
485 if (linelen >= 3 && isdigit(line[0]) && isdigit(line[1])
486 && isdigit(line[2])) {
488 * We have a 3-digit response code.
490 code = (line[0] - '0')*100 + (line[1] - '0')*10 + (line[2] - '0');
491 proto_tree_add_uint(smtp_tree, hf_smtp_rsp_code, tvb, offset, 3,
495 proto_tree_add_item(smtp_tree, hf_smtp_rsp_parameter, tvb,
496 offset + 4, linelen - 4, FALSE);
500 * No 3-digit response code.
502 proto_tree_add_text(smtp_tree, tvb, offset, linelen,
503 "Bogus reply line (no response code): %s",
504 tvb_format_text(tvb, offset, linelen));
508 * Step past this line.
510 offset = next_offset;
513 * If it's not a continuation line, quit.
515 if (!is_continuation_line)
524 /* Register all the bits needed by the filtering engine */
527 proto_register_smtp(void)
529 static hf_register_info hf[] = {
531 { "Request", "smtp.req", FT_BOOLEAN, BASE_NONE, NULL, 0x0, "", HFILL }},
534 { "Response", "smtp.rsp", FT_BOOLEAN, BASE_NONE, NULL, 0x0, "", HFILL }},
536 { &hf_smtp_req_command,
537 { "Command", "smtp.req.command", FT_STRING, BASE_NONE, NULL, 0x0,
540 { &hf_smtp_req_parameter,
541 { "Request parameter", "smtp.req.parameter", FT_STRING, BASE_NONE, NULL, 0x0,
545 { "Response code", "smtp.response.code", FT_UINT32, BASE_DEC, NULL, 0x0,
548 { &hf_smtp_rsp_parameter,
549 { "Response parameter", "smtp.rsp.parameter", FT_STRING, BASE_NONE, NULL, 0x0,
552 static gint *ett[] = {
555 module_t *smtp_module;
557 /* No Configuration options to register? */
559 proto_smtp = proto_register_protocol("Simple Mail Transfer Protocol",
562 proto_register_field_array(proto_smtp, hf, array_length(hf));
563 proto_register_subtree_array(ett, array_length(ett));
564 register_init_routine(&smtp_init_protocol);
566 smtp_module = prefs_register_protocol(proto_smtp, NULL);
567 prefs_register_bool_preference(smtp_module, "desegment_lines",
568 "Desegment all SMTP command and response lines spanning multiple TCP segments",
569 "Whether the SMTP dissector should desegment all command and response lines spanning multiple TCP segments",
573 /* The registration hand-off routine */
575 proto_reg_handoff_smtp(void)
577 static int smtp_prefs_initialized = FALSE;
578 static dissector_handle_t smtp_handle;
579 static int tcp_port = 0;
581 if (!smtp_prefs_initialized) {
583 smtp_handle = create_dissector_handle(dissect_smtp, proto_smtp);
585 smtp_prefs_initialized = TRUE;
590 dissector_delete("tcp.port", tcp_port, smtp_handle);
594 tcp_port = global_smtp_tcp_port;
596 dissector_add("tcp.port", global_smtp_tcp_port, smtp_handle);