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wireshark/packet-smtp.c

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/* packet-smtp.c
* Routines for SMTP packet disassembly
*
* $Id: packet-smtp.c,v 1.19 2001/07/03 04:56:46 guy Exp $
*
* Copyright (c) 2000 by Richard Sharpe <rsharpe@ns.aus.com>
*
* Ethereal - Network traffic analyzer
* By Gerald Combs
* Copyright 1999 Gerald Combs
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* 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.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#ifdef HAVE_SYS_TYPES_H
# include <sys/types.h>
#endif
#ifdef HAVE_NETINET_IN_H
#include <netinet/in.h>
#endif
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <time.h>
#include <glib.h>
#include <string.h>
#include "packet.h"
#include "conversation.h"
#include "resolv.h"
#include "prefs.h"
#include "strutil.h"
#define TCP_PORT_SMTP 25
void proto_reg_handoff_smtp(void);
static int proto_smtp = -1;
static int hf_smtp_req = -1;
static int hf_smtp_rsp = -1;
static int ett_smtp = -1;
static int global_smtp_tcp_port = TCP_PORT_SMTP;
/*
* A CMD is an SMTP command, MESSAGE is the message portion, and EOM is the
* last part of a message
*/
#define SMTP_PDU_CMD 0
#define SMTP_PDU_MESSAGE 1
#define SMTP_PDU_EOM 2
struct smtp_proto_data {
guint16 pdu_type;
};
static int smtp_packet_init_count = 100;
struct smtp_request_key {
guint32 conversation;
};
/*
* State information stored with a conversation.
*/
struct smtp_request_val {
gboolean reading_data; /* Reading message data, not commands */
guint16 crlf_seen; /* Have we seen a CRLF on the end of a packet */
};
GHashTable *smtp_request_hash = NULL;
GMemChunk *smtp_request_keys = NULL;
GMemChunk *smtp_request_vals = NULL;
GMemChunk *smtp_packet_infos = NULL;
/* Hash Functions */
gint
smtp_equal(gconstpointer v, gconstpointer w)
{
struct smtp_request_key *v1 = (struct smtp_request_key *)v;
struct smtp_request_key *v2 = (struct smtp_request_key *)w;
#if defined(DEBUG_SMTP_HASH)
printf("Comparing %08X\n and %08X\n",
v1->conversation, v2->conversation);
#endif
if (v1->conversation == v2->conversation)
return 1;
return 0;
}
static guint
smtp_hash(gconstpointer v)
{
struct smtp_request_key *key = (struct smtp_request_key *)v;
guint val;
val = key->conversation;
#if defined(DEBUG_SMTP_HASH)
printf("SMTP Hash calculated as %u\n", val);
#endif
return val;
}
static void
smtp_init_protocol(void)
{
#if defined(DEBUG_SMTP_HASH)
printf("Initializing SMTP hashtable area\n");
#endif
if (smtp_request_hash)
g_hash_table_destroy(smtp_request_hash);
if (smtp_request_keys)
g_mem_chunk_destroy(smtp_request_keys);
if (smtp_request_vals)
g_mem_chunk_destroy(smtp_request_vals);
if (smtp_packet_infos)
g_mem_chunk_destroy(smtp_packet_infos);
smtp_request_hash = g_hash_table_new(smtp_hash, smtp_equal);
smtp_request_keys = g_mem_chunk_new("smtp_request_keys",
sizeof(struct smtp_request_key),
smtp_packet_init_count * sizeof(struct smtp_request_key), G_ALLOC_AND_FREE);
smtp_request_vals = g_mem_chunk_new("smtp_request_vals",
sizeof(struct smtp_request_val),
smtp_packet_init_count * sizeof(struct smtp_request_val), G_ALLOC_AND_FREE);
smtp_packet_infos = g_mem_chunk_new("smtp_packet_infos",
sizeof(struct smtp_proto_data),
smtp_packet_init_count * sizeof(struct smtp_proto_data), G_ALLOC_AND_FREE);
}
static void
dissect_smtp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{
struct smtp_proto_data *frame_data;
proto_tree *smtp_tree;
proto_item *ti;
int offset = 0;
int request = 0;
conversation_t *conversation;
struct smtp_request_key request_key, *new_request_key;
struct smtp_request_val *request_val;
const char *line;
int linelen;
gboolean eom_seen = FALSE;
gint next_offset;
gboolean is_continuation_line;
int cmdlen;
/* As there is no guarantee that we will only see frames in the
* the SMTP conversation once, and that we will see them in
* order - in Ethereal, the user could randomly click on frames
* in the conversation in any order in which they choose - we
* have to store information with each frame indicating whether
* it contains commands or data or an EOM indication.
*
* XXX - what about frames that contain *both*? TCP is a
* byte-stream protocol, and there are no guarantees that
* TCP segment boundaries will correspond to SMTP commands
* or EOM indications.
*
* We only need that for the client->server stream; responses
* are easy to manage.
*
* If we have per frame data, use that, else, we must be on the first
* pass, so we figure it out on the first pass.
*/
/* Find out what conversation this packet is part of ... but only
* if we have no information on this packet, so find the per-frame
* info first.
*/
/* SMTP messages have a simple format ... */
request = pinfo -> destport == pinfo -> match_port;
/*
* Get the first line from the buffer.
*
* Note that "tvb_find_line_end()" will return a value that
* is not longer than what's in the buffer, so the
* "tvb_get_ptr()" call won't throw an exception.
*/
linelen = tvb_find_line_end(tvb, offset, -1, &next_offset);
line = tvb_get_ptr(tvb, offset, linelen);
frame_data = p_get_proto_data(pinfo->fd, proto_smtp);
if (!frame_data) {
conversation = find_conversation(&pinfo->src, &pinfo->dst, pinfo->ptype,
pinfo->srcport, pinfo->destport, 0);
if (conversation == NULL) { /* No conversation, create one */
conversation = conversation_new(&pinfo->src, &pinfo->dst, pinfo->ptype,
pinfo->srcport, pinfo->destport, NULL,
0);
}
/*
* Check for and insert an entry in the request table if does not exist
*/
request_key.conversation = conversation->index;
request_val = (struct smtp_request_val *)g_hash_table_lookup(smtp_request_hash, &request_key);
if (!request_val) { /* Create one */
new_request_key = g_mem_chunk_alloc(smtp_request_keys);
new_request_key->conversation = conversation->index;
request_val = g_mem_chunk_alloc(smtp_request_vals);
request_val->reading_data = FALSE;
request_val->crlf_seen = 0;
g_hash_table_insert(smtp_request_hash, new_request_key, request_val);
}
/*
* Check whether or not this packet is an end of message packet
* We should look for CRLF.CRLF and they may be split.
* We have to keep in mind that we may see what we want on
* two passes through here ...
*/
if (request_val->reading_data) {
/*
* The order of these is important ... We want to avoid
* cases where there is a CRLF at the end of a packet and a
* .CRLF at the begining of the same packet.
*/
if ((request_val->crlf_seen && tvb_strneql(tvb, offset, ".\r\n", 3) == 0) ||
tvb_strneql(tvb, offset, "\r\n.\r\n", 5) == 0) {
eom_seen = TRUE;
}
if (tvb_strneql(tvb, offset + tvb_length_remaining(tvb, offset) - 2, "\r\n", 2) == 0) {
request_val->crlf_seen = 1;
}
else {
request_val->crlf_seen = 0;
}
}
/*
* OK, Check if we have seen a DATA request. We do it here for
* simplicity, but we have to be careful below.
*/
if (request) {
frame_data = g_mem_chunk_alloc(smtp_packet_infos);
if (request_val->reading_data) {
/*
* This is message data.
*/
if (eom_seen) { /* Seen the EOM */
/*
* EOM.
* Everything that comes after it is commands.
*
* XXX - what if the EOM isn't at the beginning of
* the TCP segment? It can occur anywhere....
*/
frame_data->pdu_type = SMTP_PDU_EOM;
request_val->reading_data = FALSE;
} else {
/*
* Message data with no EOM.
*/
frame_data->pdu_type = SMTP_PDU_MESSAGE;
}
} else {
/*
* This is commands - unless the capture started in the
* middle of a session, and we're in the middle of data.
* To quote RFC 821, "Command codes are four alphabetic
* characters"; if we don't see four alphabetic characters
* and, if there's anything else in the line, a space, we
* assume it's not a command.
* (We treat only A-Z and a-z as alphabetic.)
*/
#define ISALPHA(c) (((c) >= 'A' && (c) <= 'Z') || \
((c) >= 'a' && (c) <= 'z'))
if (linelen >= 4 && ISALPHA(line[0]) && ISALPHA(line[1]) &&
ISALPHA(line[2]) && ISALPHA(line[3]) &&
(linelen == 4 || line[4] == ' ')) {
if (strncasecmp(line, "DATA", 4) == 0) {
/*
* DATA command.
* This is a command, but everything that comes after it,
* until an EOM, is data.
*/
frame_data->pdu_type = SMTP_PDU_CMD;
request_val->reading_data = TRUE;
} else {
/*
* Regular command.
*/
frame_data->pdu_type = SMTP_PDU_CMD;
}
} else {
/*
* Assume it's message data.
*/
frame_data->pdu_type = SMTP_PDU_MESSAGE;
}
}
p_add_proto_data(pinfo->fd, proto_smtp, frame_data);
}
}
/*
* From here, we simply add items to the tree and info to the info
* fields ...
*/
if (check_col(pinfo->fd, COL_PROTOCOL))
col_set_str(pinfo->fd, COL_PROTOCOL, "SMTP");
if (check_col(pinfo->fd, COL_INFO)) { /* Add the appropriate type here */
/*
* If it is a request, we have to look things up, otherwise, just
* display the right things
*/
if (request) {
/* We must have frame_data here ... */
switch (frame_data->pdu_type) {
case SMTP_PDU_MESSAGE:
col_set_str(pinfo->fd, COL_INFO, "Message Body");
break;
case SMTP_PDU_EOM:
col_add_fstr(pinfo->fd, COL_INFO, "EOM: %s",
format_text(line, linelen));
break;
case SMTP_PDU_CMD:
col_add_fstr(pinfo->fd, COL_INFO, "Command: %s",
format_text(line, linelen));
break;
}
}
else {
col_add_fstr(pinfo->fd, COL_INFO, "Response: %s",
format_text(line, linelen));
}
}
if (tree) { /* Build the tree info ... */
ti = proto_tree_add_item(tree, proto_smtp, tvb, offset,
tvb_length_remaining(tvb, offset), FALSE);
smtp_tree = proto_item_add_subtree(ti, ett_smtp);
proto_tree_add_boolean_hidden(smtp_tree, (request ? hf_smtp_req : hf_smtp_rsp),
tvb, offset, 4, TRUE);
if (request) {
/*
* Check out whether or not we can see a command in there ...
* What we are looking for is not data_seen and the word DATA
* and not eom_seen.
*
* We will see DATA and request_val->data_seen when we process the
* tree view after we have seen a DATA packet when processing
* the packet list pane.
*
* On the first pass, we will not have any info on the packets
* On second and subsequent passes, we will.
*/
switch (frame_data->pdu_type) {
case SMTP_PDU_MESSAGE:
/*
* Message body.
* Put its lines into the protocol tree, a line at a time.
*/
while (tvb_offset_exists(tvb, offset)) {
/*
* Find the end of the line.
*/
tvb_find_line_end(tvb, offset, -1, &next_offset);
/*
* Put this line.
*/
proto_tree_add_text(smtp_tree, tvb, offset, next_offset - offset,
"Message: %s",
tvb_format_text(tvb, offset, next_offset - offset));
/*
* Step to the next line.
*/
offset = next_offset;
}
break;
case SMTP_PDU_EOM:
/*
* End-of-message-body indicator.
*
* XXX - what about stuff after the first line?
* Unlikely, as the client should wait for a response to the
* DATA command this terminates before sending another
* request, but we should probably handle it.
*/
proto_tree_add_text(smtp_tree, tvb, offset, linelen,
"EOM: %s", format_text(line, linelen));
break;
case SMTP_PDU_CMD:
/*
* Command.
*
* XXX - what about stuff after the first line?
* Unlikely, as the client should wait for a response to the
* previous command before sending another request, but we
* should probably handle it.
*/
if (linelen >= 4)
cmdlen = 4;
else
cmdlen = linelen;
proto_tree_add_text(smtp_tree, tvb, offset, cmdlen,
"Command: %s", format_text(line, cmdlen));
if (linelen > 5) {
proto_tree_add_text(smtp_tree, tvb, offset + 5, linelen - 5,
"Parameter: %s", format_text(line + 5, linelen - 5));
}
}
}
else {
/*
* Process the response, a line at a time, until we hit a line
* that doesn't have a continuation indication on it.
*/
while (tvb_offset_exists(tvb, offset)) {
/*
* Find the end of the line.
*/
linelen = tvb_find_line_end(tvb, offset, -1, &next_offset);
/*
* Is it a continuation line?
*/
is_continuation_line =
(linelen >= 4 && tvb_get_guint8(tvb, offset + 3) == '-');
/*
* Put it into the protocol tree.
*/
proto_tree_add_text(smtp_tree, tvb, offset, 3,
"Response: %s", tvb_format_text(tvb, offset, 3));
if (linelen >= 4) {
proto_tree_add_text(smtp_tree, tvb, offset + 4, linelen - 4,
"Parameter: %s", tvb_format_text(tvb, offset + 4, linelen - 4));
}
/*
* Step past this line.
*/
offset = next_offset;
/*
* If it's not a continuation line, quit.
*/
if (!is_continuation_line)
break;
}
}
}
}
/* Register all the bits needed by the filtering engine */
void
proto_register_smtp(void)
{
static hf_register_info hf[] = {
{ &hf_smtp_req,
{ "Request", "smtp.req", FT_BOOLEAN, BASE_NONE, NULL, 0x0, "", HFILL }},
{ &hf_smtp_rsp,
{ "Response", "smtp.rsp", FT_BOOLEAN, BASE_NONE, NULL, 0x0, "", HFILL }},
};
static gint *ett[] = {
&ett_smtp
};
/*module_t *smtp_module = NULL; */ /* Not yet used */
/* No Configuration options to register? */
proto_smtp = proto_register_protocol("Simple Mail Transfer Protocol",
"SMTP", "smtp");
proto_register_field_array(proto_smtp, hf, array_length(hf));
proto_register_subtree_array(ett, array_length(ett));
register_init_routine(&smtp_init_protocol);
}
/* The registration hand-off routine */
void
proto_reg_handoff_smtp(void)
{
static int smtp_prefs_initialized = FALSE;
static int tcp_port = 0;
if (smtp_prefs_initialized) {
dissector_delete("tcp.port", tcp_port, dissect_smtp);
}
else {
smtp_prefs_initialized = TRUE;
}
tcp_port = global_smtp_tcp_port;
dissector_add("tcp.port", global_smtp_tcp_port, dissect_smtp, proto_smtp);
}
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