390 lines
11 KiB
C
390 lines
11 KiB
C
/* req_resp_hdrs.c
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* Routines handling protocols with a request/response line, headers,
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* a blank line, and an optional body.
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*
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* $Id$
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*
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* Wireshark - Network traffic analyzer
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* By Gerald Combs <gerald@wireshark.org>
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* Copyright 1998 Gerald Combs
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*/
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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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#include <glib.h>
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#include <epan/packet.h>
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#include <epan/strutil.h>
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#include <string.h>
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#include <epan/req_resp_hdrs.h>
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/*
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* Optionally do reassembly of the request/response line, headers, and body.
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*/
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gboolean
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req_resp_hdrs_do_reassembly(tvbuff_t *tvb, const int offset, packet_info *pinfo,
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const gboolean desegment_headers, const gboolean desegment_body)
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{
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gint next_offset;
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gint next_offset_sav;
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gint length_remaining, reported_length_remaining;
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int linelen;
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gchar *header_val;
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long int content_length;
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gboolean content_length_found = FALSE;
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gboolean content_type_found = FALSE;
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gboolean chunked_encoding = FALSE;
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gboolean keepalive_found = FALSE;
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/*
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* Do header desegmentation if we've been told to.
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*
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* RFC 2616 defines HTTP messages as being either of the
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* Request or the Response type
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* (HTTP-message = Request | Response).
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* Request and Response are defined as:
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* Request = Request-Line
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* *(( general-header
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* | request-header
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* | entity-header ) CRLF)
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* CRLF
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* [ message-body ]
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* Response = Status-Line
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* *(( general-header
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* | response-header
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* | entity-header ) CRLF)
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* CRLF
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* [ message-body ]
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* that's why we can always assume two consecutive line
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* endings (we allow CR, LF, or CRLF, as some clients
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* or servers might not use a full CRLF) to mark the end
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* of the headers. The worst thing that would happen
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* otherwise would be the packet not being desegmented
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* or being interpreted as only headers.
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*
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* RFC 2326 says RTSP works the same way; RFC 3261 says SIP
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* works the same way.
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*/
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/*
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* If header desegmentation is activated, check that all
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* headers are in this tvbuff (search for an empty line
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* marking end of headers) or request one more byte (we
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* don't know how many bytes we'll need, so we just ask
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* for one).
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*/
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if (desegment_headers && pinfo->can_desegment) {
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next_offset = offset;
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for (;;) {
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next_offset_sav = next_offset;
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reported_length_remaining =
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tvb_reported_length_remaining(tvb, next_offset);
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/*
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* Request one more byte if there're no
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* bytes left in the reported data (if there're
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* bytes left in the reported data, but not in
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* the available data, requesting more bytes
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* won't help, as those bytes weren't captured).
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*/
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if (reported_length_remaining < 1) {
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pinfo->desegment_offset = offset;
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pinfo->desegment_len = DESEGMENT_ONE_MORE_SEGMENT;
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return FALSE;
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}
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length_remaining = tvb_length_remaining(tvb,
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next_offset);
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/*
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* Request one more byte if we cannot find a
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* header (i.e. a line end).
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*/
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linelen = tvb_find_line_end(tvb, next_offset,
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-1, &next_offset, TRUE);
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if (linelen == -1 &&
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length_remaining >= reported_length_remaining) {
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/*
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* Not enough data; ask for one more
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* byte.
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*/
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pinfo->desegment_offset = offset;
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pinfo->desegment_len = DESEGMENT_ONE_MORE_SEGMENT;
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return FALSE;
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}
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if (linelen == 0) {
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/*
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* We found the end of the headers.
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*/
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break;
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}
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/*
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* Is this a Content-Length or Transfer-Encoding
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* header? If not, it either means that we are in
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* a different header line, or that we are
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* at the end of the headers, or that there
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* isn't enough data; the two latter cases
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* have already been handled above.
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*/
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if (desegment_body) {
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/*
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* Check if we've found Content-Length.
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*/
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if (tvb_strncaseeql(tvb, next_offset_sav,
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"Content-Length:", 15) == 0) {
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header_val = tvb_get_ephemeral_string(tvb,
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next_offset_sav + 15,
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linelen - 15);
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if (sscanf(header_val,
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"%li", &content_length)
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== 1)
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content_length_found = TRUE;
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} else if (tvb_strncaseeql(tvb, next_offset_sav,
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"Content-Type:", 13) == 0) {
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content_type_found = TRUE;
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} else if (tvb_strncaseeql(tvb, next_offset_sav,
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"Connection:", 11) == 0) {
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/* Check for keep-alive */
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header_val = tvb_get_ephemeral_string(tvb,
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next_offset_sav + 11,
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linelen - 11);
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if(header_val){
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while(*header_val==' '){
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header_val++;
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}
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if(!g_ascii_strncasecmp(header_val, "Keep-Alive", 10)){
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keepalive_found = TRUE;
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}
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}
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} else if (tvb_strncaseeql(tvb,
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next_offset_sav,
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"Transfer-Encoding:", 18) == 0) {
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/*
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* Find out if this Transfer-Encoding is
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* chunked. It should be, since there
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* really aren't any other types, but
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* RFC 2616 allows for them.
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*/
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gchar *p;
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guint len;
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header_val = tvb_get_ephemeral_string(tvb,
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next_offset_sav + 18, linelen - 18);
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p = header_val;
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len = (guint) strlen(header_val);
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/* Skip white space */
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while (p < header_val + len &&
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(*p == ' ' || *p == '\t'))
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p++;
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if (p <= header_val + len) {
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if (g_ascii_strncasecmp(p, "chunked", 7)
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== 0) {
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/*
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* Don't bother looking
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* for extensions;
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* since we don't
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* understand them,
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* they should be
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* ignored.
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*/
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chunked_encoding = TRUE;
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}
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}
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}
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}
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}
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}
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/*
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* The above loop ends when we reached the end of the headers, so
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* there should be content_length bytes after the 4 terminating bytes
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* and next_offset points to after the end of the headers.
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*/
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if (desegment_body) {
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if (content_length_found) {
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/* next_offset has been set to the end of the headers */
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if (!tvb_bytes_exist(tvb, next_offset, content_length)) {
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length_remaining = tvb_length_remaining(tvb,
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next_offset);
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reported_length_remaining =
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tvb_reported_length_remaining(tvb, next_offset);
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if (length_remaining < reported_length_remaining) {
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/*
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* It's a waste of time asking for more
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* data, because that data wasn't captured.
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*/
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return TRUE;
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}
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if (length_remaining == -1)
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length_remaining = 0;
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pinfo->desegment_offset = offset;
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pinfo->desegment_len =
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content_length - length_remaining;
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return FALSE;
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}
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} else if (chunked_encoding) {
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/*
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* This data is chunked, so we need to keep pulling
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* data until we reach the end of the stream, or a
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* zero sized chunk.
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*
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* XXX
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* This doesn't bother with trailing headers; I don't
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* think they are really used, and we'd have to use
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* is_http_request_or_reply() to determine if it was
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* a trailing header, or the start of a new response.
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*/
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gboolean done_chunking = FALSE;
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while (!done_chunking) {
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gint chunk_size = 0;
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gint chunk_offset = 0;
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gchar *chunk_string = NULL;
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gchar *c = NULL;
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reported_length_remaining =
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tvb_reported_length_remaining(tvb,
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next_offset);
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if (reported_length_remaining < 1) {
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pinfo->desegment_offset = offset;
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pinfo->desegment_len = DESEGMENT_ONE_MORE_SEGMENT;
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return FALSE;
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}
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length_remaining = tvb_length_remaining(tvb,
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next_offset);
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linelen = tvb_find_line_end(tvb, next_offset,
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-1, &chunk_offset, TRUE);
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if (linelen == -1 &&
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length_remaining >=
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reported_length_remaining) {
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pinfo->desegment_offset = offset;
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pinfo->desegment_len = DESEGMENT_ONE_MORE_SEGMENT;
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return FALSE;
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}
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/* We have a line with the chunk size in it.*/
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chunk_string = tvb_get_ephemeral_string(tvb, next_offset,
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linelen);
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c = chunk_string;
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/*
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* We don't care about the extensions.
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*/
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if ((c = strchr(c, ';'))) {
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*c = '\0';
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}
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if ((sscanf(chunk_string, "%x",
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&chunk_size) < 0) || chunk_size < 0) {
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/* We couldn't get the chunk size,
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* so stop trying.
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*/
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return TRUE;
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}
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if (chunk_size == 0) {
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/*
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* This is the last chunk. Let's pull in the
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* trailing CRLF.
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*/
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linelen = tvb_find_line_end(tvb,
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chunk_offset, -1, &chunk_offset, TRUE);
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if (linelen == -1 &&
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length_remaining >=
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reported_length_remaining) {
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pinfo->desegment_offset = offset;
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pinfo->desegment_len = DESEGMENT_ONE_MORE_SEGMENT;
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return FALSE;
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}
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pinfo->desegment_offset = chunk_offset;
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pinfo->desegment_len = 0;
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done_chunking = TRUE;
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} else {
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/*
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* Skip to the next chunk if we
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* already have it
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*/
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if (reported_length_remaining >
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chunk_size) {
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next_offset = chunk_offset
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+ chunk_size + 2;
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} else {
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/*
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* Fetch this chunk, plus the
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* trailing CRLF.
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*/
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pinfo->desegment_offset = offset;
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pinfo->desegment_len = DESEGMENT_ONE_MORE_SEGMENT;
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return FALSE;
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}
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}
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}
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} else if (content_type_found && pinfo->can_desegment) {
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/* We found a content-type but no content-length.
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* This is probably a HTTP header for a session with
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* only one HTTP PDU and where the content spans
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* until the end of the tcp session, unless there
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* is a keepalive header present in which case we
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* assume there is no message body at all and thus
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* we wont do any reassembly.
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* Set up tcp reassembly until the end of this session.
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*/
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length_remaining = tvb_length_remaining(tvb, next_offset);
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reported_length_remaining = tvb_reported_length_remaining(tvb, next_offset);
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if (length_remaining < reported_length_remaining) {
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/*
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* It's a waste of time asking for more
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* data, because that data wasn't captured.
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*/
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return TRUE;
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}
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if (keepalive_found) {
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/* We have a keep-alive but no content-length.
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* Assume there is no message body and dont
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* do any reassembly.
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*/
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return TRUE;
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}
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pinfo->desegment_offset = offset;
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pinfo->desegment_len = DESEGMENT_UNTIL_FIN;
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return FALSE;
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}
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}
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/*
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* No further desegmentation needed.
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*/
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return TRUE;
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}
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