diff options
author | Guy Harris <guy@alum.mit.edu> | 2001-03-28 07:49:41 +0000 |
---|---|---|
committer | Guy Harris <guy@alum.mit.edu> | 2001-03-28 07:49:41 +0000 |
commit | c00e9c43dc7cc3bcd2e5dc83390909f81a572551 (patch) | |
tree | ebb3faf4eaefb285d5c8a6b35e8166ef9535dfa4 /packet-tpkt.c | |
parent | 28531d2efd66f3ec0b50c4f5f2843d9dcc3e63a9 (diff) |
Support for TPKT being used for its original purpose (TCP port > 102,
containing OSI transport layer PDUs).
Enable the Q.931-inside-TPKT code (but not the H.225 stuff, as that
requires Andreas Sikkema's H.225 dissector). Update it to match his
current modified Q.931 dissector.
svn path=/trunk/; revision=3199
Diffstat (limited to 'packet-tpkt.c')
-rw-r--r-- | packet-tpkt.c | 134 |
1 files changed, 91 insertions, 43 deletions
diff --git a/packet-tpkt.c b/packet-tpkt.c index a1e11103dd..b25e1154b1 100644 --- a/packet-tpkt.c +++ b/packet-tpkt.c @@ -1,9 +1,12 @@ /* packet-tpkt.c * - * Routines for TPKT dissection + * Routine to check for RFC 1006 TPKT header and to dissect TPKT header * Copyright 2000, Philips Electronics N.V. * Andreas Sikkema <andreas.sikkema@philips.com> * + * Routine to dissect RFC 1006 TPKT packet containing OSI TP PDU + * Copyright 2001, Martin Thomas <Martin_A_Thomas@yahoo.com> + * * Ethereal - Network traffic analyzer * By Gerald Combs <gerald@zing.org> * Copyright 1998 Gerald Combs @@ -24,20 +27,6 @@ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ -/* - * This dissector tries to dissect the TPKT protocol according to - * RFC 1006 - * - * IMPORTANT IMPORTANT IMPORTANT IMPORTANT IMPORTANT IMPORTANT IMPORTANT - * - * Please examine the dissector. It is NOT defined in the normal way! - * Some variables are references and the dissector also returns a - * value! And no, this is not a heuristic dissector! - * - * IMPORTANT IMPORTANT IMPORTANT IMPORTANT IMPORTANT IMPORTANT IMPORTANT - */ - - #ifdef HAVE_CONFIG_H # include "config.h" #endif @@ -67,71 +56,123 @@ static int hf_tpkt_length = -1; /* TPKT fields defining a sub tree */ static gint ett_tpkt = -1; -int +#define TCP_PORT_TPKT 102 + +/* find the dissector for OSI TP (aka COTP) */ +static dissector_handle_t osi_tp_handle; + +/* + * Check whether this could be a TPKT-encapsulated PDU. + */ +gboolean is_tpkt( tvbuff_t *tvb, unsigned int* offset ) { - if ( (*offset) + 4 > tvb_length( tvb ) ) return FALSE; + /* There should at least be 4 bytes left in the frame */ + if ( (*offset) + 4 > tvb_length( tvb ) ) + return FALSE; /* there isn't */ + /* + * The first octet should be 3 and the second one should be 0 + * The H.323 implementers guide suggests that this migh not + * always be the case.... + */ if ( ! ( ( tvb_get_guint8( tvb, ( *offset ) ) == 3 ) && - ( tvb_get_guint8( tvb, ( *offset ) + 1 ) == 0 ) ) ) return FALSE; + ( tvb_get_guint8( tvb, ( *offset ) + 1 ) == 0 ) ) ) + return FALSE; /* They're not */ - return TRUE; + return TRUE; } +/* + * Dissect the TPKT header; called from the TPKT dissector, as well as + * from dissectors such as the dissector for Q.931-over-TCP. + * + * Returns -1 if we didn't dissect it as a TPKT header, otherwise returns + * the PDU length from the TPKT header. + * + * Sets "*offset" to the offset following the TPKT header. + */ int -dissect_tpkt( tvbuff_t *tvb, unsigned int* offset, packet_info *pinfo, proto_tree *tree ) +dissect_tpkt_header( tvbuff_t *tvb, unsigned int* offset, packet_info *pinfo, proto_tree *tree ) { proto_item *ti = NULL; proto_tree *tpkt_tree = NULL; - unsigned int data_len = 0; + guint16 data_len; + /* + * If TPKT is disabled, don't dissect it, just return -1, meaning + * "this isn't TPKT". + */ + if (!proto_is_protocol_enabled(proto_tpkt)) + return -1; pinfo->current_proto = "TPKT"; - /* There should at least be 4 bytes left in the frame */ - if ( (*offset) + 4 > tvb_length( tvb ) ) return -1; - /* - * The first octet should be 3 and the second one should be 0 - * The H.323 implementers guide suggests that this migh not - * always be the case.... - */ - if ( ! ( ( tvb_get_guint8( tvb, ( *offset ) ) == 3 ) && - ( tvb_get_guint8( tvb, ( *offset ) + 1 ) == 0 ) ) ) return -1; - if ( check_col( pinfo->fd, COL_PROTOCOL ) ) { col_set_str( pinfo->fd, COL_PROTOCOL, "TPKT" ); } - if ( check_col( pinfo->fd, COL_INFO) ) { - /*data_len = pntohs( &pd[ (*offset) + 2 ] );*/ - data_len = tvb_get_ntohs( tvb, (*offset) + 2 ); + data_len = tvb_get_ntohs( tvb, (*offset) + 2 ); - col_add_fstr( pinfo->fd, COL_INFO, "TPKT Data length = %d", data_len ); + if ( check_col( pinfo->fd, COL_INFO) ) { + col_add_fstr( pinfo->fd, COL_INFO, "TPKT Data length = %u", + data_len ); } if ( tree ) { - ti = proto_tree_add_item( tree, proto_tpkt, tvb, (*offset), 4, FALSE ); + ti = proto_tree_add_item( tree, proto_tpkt, tvb, (*offset), 4, + FALSE ); tpkt_tree = proto_item_add_subtree( ti, ett_tpkt ); /* Version 1st octet */ - proto_tree_add_item( tpkt_tree, hf_tpkt_version, tvb, (*offset), 1, FALSE ); + proto_tree_add_item( tpkt_tree, hf_tpkt_version, tvb, + (*offset), 1, FALSE ); (*offset)++; /* Reserved octet*/ - proto_tree_add_item( tpkt_tree, hf_tpkt_reserved, tvb, (*offset), 1, FALSE ); + proto_tree_add_item( tpkt_tree, hf_tpkt_reserved, tvb, + (*offset), 1, FALSE ); (*offset)++; } else { (*offset) += 2; } - /* Length, two octets */ - /*data_len = pntohs( &pd[ (*offset) ] );*/ - data_len = tvb_get_ntohs( tvb, (*offset) ); if ( tree ) - proto_tree_add_uint_format( tpkt_tree, hf_tpkt_length, tvb, (*offset), 2, data_len, "Length: %d", data_len ); + proto_tree_add_uint( tpkt_tree, hf_tpkt_length, tvb, + (*offset), 2, data_len ); (*offset) += 2; return data_len; } +/* + * Dissect RFC 1006 TPKT, which wraps a TPKT header around an OSI TP + * PDU. + */ +static void +dissect_tpkt( tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree ) +{ + int tpkt_len; + int offset = 0; + int length, reported_length; + tvbuff_t *next_tvb; + + /* Dissect the TPKT header. */ + tpkt_len = dissect_tpkt_header(tvb, &offset, pinfo, tree); + + /* + * Now hand the minimum of (what's in this frame, what the TPKT + * header says is in the PDU) on to the OSI TP dissector. + */ + length = tvb_length_remaining(tvb, offset); + reported_length = tvb_reported_length_remaining(tvb, offset); + if (length > tpkt_len) + length = tpkt_len; + if (reported_length > tpkt_len) + reported_length = tpkt_len; + next_tvb = tvb_new_subset(tvb, offset, length, reported_length); + + call_dissector(osi_tp_handle, next_tvb, pinfo, tree); +} + void proto_register_tpkt(void) { @@ -173,7 +214,7 @@ proto_register_tpkt(void) "" } }, -}; + }; static gint *ett[] = { @@ -185,3 +226,10 @@ proto_register_tpkt(void) proto_register_field_array(proto_tpkt, hf, array_length(hf)); proto_register_subtree_array(ett, array_length(ett)); } + +void +proto_reg_handoff_tpkt(void) +{ + osi_tp_handle = find_dissector("ositp"); + dissector_add("tcp.port", TCP_PORT_TPKT, dissect_tpkt, proto_tpkt); +} |