#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <glib.h>
#include <epan/packet.h>
#include <epan/strutil.h>
#include <string.h>
#include <epan/req_resp_hdrs.h>
/*
* Optionally do reassembly of the request/response line, headers, and body.
*/
gboolean
req_resp_hdrs_do_reassembly(tvbuff_t *tvb, const int offset, packet_info *pinfo,
const gboolean desegment_headers, const gboolean desegment_body)
{
gint next_offset;
gint next_offset_sav;
gint length_remaining, reported_length_remaining;
int linelen;
gchar *header_val;
long int content_length;
gboolean content_length_found = FALSE;
gboolean content_type_found = FALSE;
gboolean chunked_encoding = FALSE;
gboolean keepalive_found = FALSE;
/*
* Do header desegmentation if we've been told to.
*
* RFC 2616 defines HTTP messages as being either of the
* Request or the Response type
* (HTTP-message = Request | Response).
* Request and Response are defined as:
* Request = Request-Line
* *(( general-header
* | request-header
* | entity-header ) CRLF)
* CRLF
* [ message-body ]
* Response = Status-Line
* *(( general-header
* | response-header
* | entity-header ) CRLF)
* CRLF
* [ message-body ]
* that's why we can always assume two consecutive line
* endings (we allow CR, LF, or CRLF, as some clients
* or servers might not use a full CRLF) to mark the end
* of the headers. The worst thing that would happen
* otherwise would be the packet not being desegmented
* or being interpreted as only headers.
*
* RFC 2326 says RTSP works the same way; RFC 3261 says SIP
* works the same way.
*/
/*
* If header desegmentation is activated, check that all
* headers are in this tvbuff (search for an empty line
* marking end of headers) or request one more byte (we
* don't know how many bytes we'll need, so we just ask
* for one).
*/
if (desegment_headers && pinfo->can_desegment) {
next_offset = offset;
for (;;) {
next_offset_sav = next_offset;
reported_length_remaining =
tvb_reported_length_remaining(tvb, next_offset);
/*
* Request one more byte if there're no
* bytes left in the reported data (if there're
* bytes left in the reported data, but not in
* the available data, requesting more bytes
* won't help, as those bytes weren't captured).
*/
if (reported_length_remaining < 1) {
pinfo->desegment_offset = offset;
pinfo->desegment_len = DESEGMENT_ONE_MORE_SEGMENT;
return FALSE;
}
length_remaining = tvb_length_remaining(tvb,
next_offset);
/*
* Request one more byte if we cannot find a
* header (i.e. a line end).
*/
linelen = tvb_find_line_end(tvb, next_offset,
-1, &next_offset, TRUE);
if (linelen == -1 &&
length_remaining >= reported_length_remaining) {
/*
* Not enough data; ask for one more
* byte.
*/
pinfo->desegment_offset = offset;
pinfo->desegment_len = DESEGMENT_ONE_MORE_SEGMENT;
return FALSE;
}
if (linelen == 0) {
/*
* We found the end of the headers.
*/
break;
}
/*
* Is this a Content-Length or Transfer-Encoding
* header? If not, it either means that we are in
* a different header line, or that we are
* at the end of the headers, or that there
* isn't enough data; the two latter cases
* have already been handled above.
*/
if (desegment_body) {
/*
* Check if we've found Content-Length.
*/
if (tvb_strncaseeql(tvb, next_offset_sav,
"Content-Length:", 15) == 0) {
header_val = tvb_get_ephemeral_string(tvb,
next_offset_sav + 15,
linelen - 15);
if (sscanf(header_val,
"%li", &content_length)
== 1)
content_length_found = TRUE;
} else if (tvb_strncaseeql(tvb, next_offset_sav,
"Content-Type:", 13) == 0) {
content_type_found = TRUE;
} else if (tvb_strncaseeql(tvb, next_offset_sav,
"Connection:", 11) == 0) {
/* Check for keep-alive */
header_val = tvb_get_ephemeral_string(tvb,
next_offset_sav + 11,
linelen - 11);
if(header_val){
while(*header_val==' '){
header_val++;
}
if(!g_ascii_strncasecmp(header_val, "Keep-Alive", 10)){
keepalive_found = TRUE;
}
}
} else if (tvb_strncaseeql(tvb,
next_offset_sav,
"Transfer-Encoding:", 18) == 0) {
/*
* Find out if this Transfer-Encoding is
* chunked. It should be, since there
* really aren't any other types, but
* RFC 2616 allows for them.
*/
gchar *p;
guint len;
header_val = tvb_get_ephemeral_string(tvb,
next_offset_sav + 18, linelen - 18);
p = header_val;
len = (guint) strlen(header_val);
/* Skip white space */
while (p < header_val + len &&
(*p == ' ' || *p == '\t'))
p++;
if (p <= header_val + len) {
if (g_ascii_strncasecmp(p, "chunked", 7)
== 0) {
/*
* Don't bother looking
* for extensions;
* since we don't
* understand them,
* they should be
* ignored.
*/
chunked_encoding = TRUE;
}
}
}
}
}
}
/*
* The above loop ends when we reached the end of the headers, so
* there should be content_length bytes after the 4 terminating bytes
* and next_offset points to after the end of the headers.
*/
if (desegment_body) {
if (content_length_found) {
/* next_offset has been set to the end of the headers */
if (!tvb_bytes_exist(tvb, next_offset, content_length)) {
length_remaining = tvb_length_remaining(tvb,
next_offset);
reported_length_remaining =
tvb_reported_length_remaining(tvb, next_offset);
if (length_remaining < reported_length_remaining) {
/*
* It's a waste of time asking for more
* data, because that data wasn't captured.
*/
return TRUE;
}
if (length_remaining == -1)
length_remaining = 0;
pinfo->desegment_offset = offset;
pinfo->desegment_len =
content_length - length_remaining;
return FALSE;
}
} else if (chunked_encoding) {
/*
* This data is chunked, so we need to keep pulling
* data until we reach the end of the stream, or a
* zero sized chunk.
*
* XXX
* This doesn't bother with trailing headers; I don't
* think they are really used, and we'd have to use
* is_http_request_or_reply() to determine if it was
* a trailing header, or the start of a new response.
*/
gboolean done_chunking = FALSE;
while (!done_chunking) {
gint chunk_size = 0;
gint chunk_offset = 0;
gchar *chunk_string = NULL;
gchar *c = NULL;
reported_length_remaining =
tvb_reported_length_remaining(tvb,
next_offset);
if (reported_length_remaining < 1) {
pinfo->desegment_offset = offset;
pinfo->desegment_len = DESEGMENT_ONE_MORE_SEGMENT;
return FALSE;
}
length_remaining = tvb_length_remaining(tvb,
next_offset);
linelen = tvb_find_line_end(tvb, next_offset,
-1, &chunk_offset, TRUE);
if (linelen == -1 &&
length_remaining >=
reported_length_remaining) {
pinfo->desegment_offset = offset;
pinfo->desegment_len = DESEGMENT_ONE_MORE_SEGMENT;
return FALSE;
}
/* We have a line with the chunk size in it.*/
chunk_string = tvb_get_ephemeral_string(tvb, next_offset,
linelen);
c = chunk_string;
/*
* We don't care about the extensions.
*/
if ((c = strchr(c, ';'))) {
*c = '\0';
}
if ((sscanf(chunk_string, "%x",
&chunk_size) < 0) || chunk_size < 0) {
/* We couldn't get the chunk size,
* so stop trying.
*/
return TRUE;
}
if (chunk_size == 0) {
/*
* This is the last chunk. Let's pull in the
* trailing CRLF.
*/
linelen = tvb_find_line_end(tvb,
chunk_offset, -1, &chunk_offset, TRUE);
if (linelen == -1 &&
length_remaining >=
reported_length_remaining) {
pinfo->desegment_offset = offset;
pinfo->desegment_len = DESEGMENT_ONE_MORE_SEGMENT;
return FALSE;
}
pinfo->desegment_offset = chunk_offset;
pinfo->desegment_len = 0;
done_chunking = TRUE;
} else {
/*
* Skip to the next chunk if we
* already have it
*/
if (reported_length_remaining >
chunk_size) {
next_offset = chunk_offset
+ chunk_size + 2;
} else {
/*
* Fetch this chunk, plus the
* trailing CRLF.
*/
pinfo->desegment_offset = offset;
pinfo->desegment_len = DESEGMENT_ONE_MORE_SEGMENT;
return FALSE;
}
}
}
} else if (content_type_found && pinfo->can_desegment) {
/* We found a content-type but no content-length.
* This is probably a HTTP header for a session with
* only one HTTP PDU and where the content spans
* until the end of the tcp session, unless there
* is a keepalive header present in which case we
* assume there is no message body at all and thus
* we wont do any reassembly.
* Set up tcp reassembly until the end of this session.
*/
length_remaining = tvb_length_remaining(tvb, next_offset);
reported_length_remaining = tvb_reported_length_remaining(tvb, next_offset);
if (length_remaining < reported_length_remaining) {
/*
* It's a waste of time asking for more
* data, because that data wasn't captured.
*/
return TRUE;
}
if (keepalive_found) {
/* We have a keep-alive but no content-length.
* Assume there is no message body and dont
* do any reassembly.
*/
return TRUE;
}
pinfo->desegment_offset = offset;
pinfo->desegment_len = DESEGMENT_UNTIL_FIN;
return FALSE;
}
}
/*
* No further desegmentation needed.
*/
return TRUE;
}