/*
* Dissect ASCII TPKT-encapsulated data in a TCP stream.
*/
void
dissect_asciitpkt(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree,
dissector_handle_t subdissector_handle)
{
proto_item *ti = NULL;
proto_tree *tpkt_tree = NULL;
volatile int offset = 0;
int length_remaining;
int data_len;
volatile int mgcp_packet_len = 0;
int mgcp_version = 0;
int mgcp_reserved = 0;
volatile int length;
tvbuff_t *volatile next_tvb;
const char *saved_proto;
guint8 string[4];
void *pd_save;
/*
* If we're reassembling segmented TPKT PDUs, empty the COL_INFO
* column, so subdissectors can append information
* without having to worry about emptying the column.
*
* We use "col_add_str()" because the subdissector
* might be appending information to the column, in
* which case we'd have to zero the buffer out explicitly
* anyway.
*/
if (tpkt_desegment)
col_set_str(pinfo->cinfo, COL_INFO, "");
while (tvb_reported_length_remaining(tvb, offset) != 0) {
/*
* Is the first byte of this putative TPKT header
* a valid TPKT version number, i.e. 3?
*/
if (tvb_get_guint8(tvb, offset) != 48) {
/*
* No, so don't assume this is a TPKT header;
* we might be in the middle of TPKT data,
* so don't get the length and don't try to
* do reassembly.
*/
col_set_str(pinfo->cinfo, COL_PROTOCOL, "TPKT");
col_set_str(pinfo->cinfo, COL_INFO, "Continuation");
if (tree) {
ti = proto_tree_add_item(tree, proto_tpkt, tvb,
offset, -1, ENC_NA);
tpkt_tree = proto_item_add_subtree(ti, ett_tpkt);
proto_item_set_text(ti, "TPKT");
proto_tree_add_text(tpkt_tree, tvb, offset, -1,
"Continuation data");
}
return;
}
length_remaining = tvb_captured_length_remaining(tvb, offset);
/*
* Get the length from the TPKT header.
*/
tvb_memcpy(tvb, (guint8 *)string, offset, 2);
mgcp_version = parseVersionText(string);
tvb_memcpy(tvb, (guint8 *)string, offset +2, 2);
mgcp_reserved = parseReservedText(string);
tvb_memcpy(tvb, (guint8 *)string, offset + 4, 4);
mgcp_packet_len = parseLengthText(string);
data_len = mgcp_packet_len;
/*
* Dissect the TPKT header.
* Save and restore "pinfo->current_proto".
*/
saved_proto = pinfo->current_proto;
pinfo->current_proto = "TPKT";
col_set_str(pinfo->cinfo, COL_PROTOCOL, "TPKT");
/*
* Don't add the TPKT header information if we're
* reassembling segmented TPKT PDUs or if this
* PDU isn't reassembled.
*
* XXX - the first is so that subdissectors can append
* information without getting TPKT stuff in the middle;
* why the second?
*/
if (!tpkt_desegment && !pinfo->fragmented) {
col_add_fstr(pinfo->cinfo, COL_INFO,
"TPKT Data length = %u", data_len);
}
if (tree) {
ti = proto_tree_add_item(tree, proto_tpkt, tvb,
offset, 8, ENC_NA);
tpkt_tree = proto_item_add_subtree(ti, ett_tpkt);
proto_item_set_text(ti, "TPKT");
/* Version */
proto_tree_add_uint(tpkt_tree, hf_tpkt_version, tvb,
offset, 2, mgcp_version);
/* Reserved octet*/
proto_tree_add_uint(tpkt_tree, hf_tpkt_reserved, tvb,
offset + 2, 2, mgcp_reserved);
/* Length */
proto_tree_add_uint(tpkt_tree, hf_tpkt_length, tvb,
offset + 4, 4, mgcp_packet_len);
}
pinfo->current_proto = saved_proto;
/* Skip the TPKT header. */
offset += TEXT_LAYER_LENGTH;
length = length_remaining - TEXT_LAYER_LENGTH;
if (length > data_len)
length = data_len;
next_tvb = tvb_new_subset(tvb, offset,length, data_len);
/*
* Call the subdissector.
*
* If it gets an error that means there's no point in
* dissecting any more TPKT messages, rethrow the
* exception in question.
*
* If it gets any other error, report it and continue, as that
* means that TPKT message got an error, but that doesn't mean
* we should stop dissecting TPKT messages within this frame
* or chunk of reassembled data.
*/
pd_save = pinfo->private_data;
TRY {
call_dissector(subdissector_handle, next_tvb, pinfo,
tree);
}
CATCH_NONFATAL_ERRORS {
/* Restore the private_data structure in case one of the
* called dissectors modified it (and, due to the exception,
* was unable to restore it).
*/
pinfo->private_data = pd_save;
show_exception(tvb, pinfo, tree, EXCEPT_CODE, GET_MESSAGE);
}
ENDTRY;
/*
* Skip the payload.
*/
offset += data_len;
}
}
/*
* Dissect ASCII TPKT-encapsulated data in a TCP stream.
*/
void
dissect_asciitpkt(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree,
dissector_handle_t subdissector_handle)
{
proto_item *ti = NULL;
proto_tree *tpkt_tree = NULL;
volatile int offset = 0;
int length_remaining;
int data_len;
int mgcp_packet_len = 0;
int mgcp_version = 0;
int mgcp_reserved = 0;
volatile int length;
tvbuff_t *volatile next_tvb;
const char *saved_proto;
guint8 string[4];
/*
* If we're reassembling segmented TPKT PDUs, empty the COL_INFO
* column, so subdissectors can append information
* without having to worry about emptying the column.
*
* We use "col_add_str()" because the subdissector
* might be appending information to the column, in
* which case we'd have to zero the buffer out explicitly
* anyway.
*/
if (tpkt_desegment && check_col(pinfo->cinfo, COL_INFO))
col_add_str(pinfo->cinfo, COL_INFO, "");
while (tvb_reported_length_remaining(tvb, offset) != 0) {
/*
* Is the first byte of this putative TPKT header
* a valid TPKT version number, i.e. 3?
*/
if (tvb_get_guint8(tvb, offset) != 48) {
/*
* No, so don't assume this is a TPKT header;
* we might be in the middle of TPKT data,
* so don't get the length and don't try to
* do reassembly.
*/
col_set_str(pinfo->cinfo, COL_PROTOCOL, "TPKT");
col_set_str(pinfo->cinfo, COL_INFO, "Continuation");
if (tree) {
ti = proto_tree_add_item(tree, proto_tpkt, tvb,
offset, -1, FALSE);
tpkt_tree = proto_item_add_subtree(ti, ett_tpkt);
proto_item_set_text(ti, "TPKT");
proto_tree_add_text(tpkt_tree, tvb, offset, -1,
"Continuation data");
}
return;
}
length_remaining = tvb_length_remaining(tvb, offset);
/*
* Get the length from the TPKT header.
*/
tvb_memcpy(tvb, (guint8 *)string, offset, 2);
mgcp_version = parseVersionText(string);
tvb_memcpy(tvb, (guint8 *)string, offset +2, 2);
mgcp_reserved = parseReservedText(string);
tvb_memcpy(tvb, (guint8 *)string, offset + 4, 4);
mgcp_packet_len = parseLengthText(string);
data_len = mgcp_packet_len;
/*
* Dissect the TPKT header.
* Save and restore "pinfo->current_proto".
*/
saved_proto = pinfo->current_proto;
pinfo->current_proto = "TPKT";
col_set_str(pinfo->cinfo, COL_PROTOCOL, "TPKT");
/*
* Don't add the TPKT header information if we're
* reassembling segmented TPKT PDUs or if this
* PDU isn't reassembled.
*
* XXX - the first is so that subdissectors can append
* information without getting TPKT stuff in the middle;
* why the second?
*/
if (!tpkt_desegment && !pinfo->fragmented
&& check_col(pinfo->cinfo, COL_INFO)) {
col_add_fstr(pinfo->cinfo, COL_INFO,
"TPKT Data length = %u", data_len);
}
if (tree) {
ti = proto_tree_add_item(tree, proto_tpkt, tvb,
offset, 8, FALSE);
tpkt_tree = proto_item_add_subtree(ti, ett_tpkt);
proto_item_set_text(ti, "TPKT");
/* Version */
proto_tree_add_uint(tpkt_tree, hf_tpkt_version, tvb,
offset, 2, mgcp_version);
/* Reserved octet*/
proto_tree_add_uint(tpkt_tree, hf_tpkt_reserved, tvb,
offset + 2, 2, mgcp_reserved);
/* Length */
proto_tree_add_uint(tpkt_tree, hf_tpkt_length, tvb,
offset + 4, 4, mgcp_packet_len);
}
pinfo->current_proto = saved_proto;
/* Skip the TPKT header. */
offset += TEXT_LAYER_LENGTH;
length = length_remaining - TEXT_LAYER_LENGTH;
if (length > data_len)
length = data_len;
next_tvb = tvb_new_subset(tvb, offset,length, data_len);
/*
* Call the subdissector.
*
* Catch the ReportedBoundsError exception; if this
* particular message happens to get a ReportedBoundsError
* exception, that doesn't mean that we should stop
* dissecting TPKT messages within this frame or chunk
* of reassembled data.
*
* If it gets a BoundsError, we can stop, as there's nothing
* more to see, so we just re-throw it.
*/
TRY {
call_dissector(subdissector_handle, next_tvb, pinfo,
tree);
}
CATCH(BoundsError) {
RETHROW;
}
CATCH(ReportedBoundsError) {
show_reported_bounds_error(tvb, pinfo, tree);
}
ENDTRY;
/*
* Skip the payload.
*/
offset += data_len;
}
}
