/* * 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; } }