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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-10 20:34:10 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-10 20:34:10 +0000 |
commit | e4ba6dbc3f1e76890b22773807ea37fe8fa2b1bc (patch) | |
tree | 68cb5ef9081156392f1dd62a00c6ccc1451b93df /epan/dissectors/packet-tpkt.c | |
parent | Initial commit. (diff) | |
download | wireshark-e4ba6dbc3f1e76890b22773807ea37fe8fa2b1bc.tar.xz wireshark-e4ba6dbc3f1e76890b22773807ea37fe8fa2b1bc.zip |
Adding upstream version 4.2.2.upstream/4.2.2
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'epan/dissectors/packet-tpkt.c')
-rw-r--r-- | epan/dissectors/packet-tpkt.c | 721 |
1 files changed, 721 insertions, 0 deletions
diff --git a/epan/dissectors/packet-tpkt.c b/epan/dissectors/packet-tpkt.c new file mode 100644 index 0000000..c029f9e --- /dev/null +++ b/epan/dissectors/packet-tpkt.c @@ -0,0 +1,721 @@ +/* packet-tpkt.c + * + * Routine to check for RFC 1006 TPKT header and to dissect TPKT header + * Copyright 2000, Philips Electronics N.V. + * Andreas Sikkema <h323@ramdyne.nl> + * + * Routine to dissect RFC 1006 TPKT packet containing OSI TP PDU + * Copyright 2001, Martin Thomas <Martin_A_Thomas@yahoo.com> + * + * Wireshark - Network traffic analyzer + * By Gerald Combs <gerald@wireshark.org> + * Copyright 1998 Gerald Combs + * + * SPDX-License-Identifier: GPL-2.0-or-later + */ + +#include "config.h" + +#include <epan/packet.h> +#include <epan/exceptions.h> +#include <epan/prefs.h> +#include <epan/show_exception.h> +#include <epan/conversation.h> + +#include "packet-tpkt.h" + +void proto_register_tpkt(void); +void proto_reg_handoff_tpkt(void); + +static heur_dissector_list_t tpkt_heur_subdissector_list; + +/* TPKT header fields */ +static int proto_tpkt = -1; +static int proto_tpkt_heur = -1; +static protocol_t *proto_tpkt_ptr; +static int hf_tpkt_version = -1; +static int hf_tpkt_reserved = -1; +static int hf_tpkt_length = -1; +static int hf_tpkt_continuation_data = -1; + + +/* TPKT fields defining a sub tree */ +static gint ett_tpkt = -1; + +/* desegmentation of OSI over TPKT over TCP */ +static gboolean tpkt_desegment = TRUE; + +#define TCP_PORT_TPKT_RANGE "102" + +/* IANA registered port for RDP (as ms-wbt-server) */ +#define TCP_PORT_RDP 3389 + +/* find the dissector for OSI TP (aka COTP) */ +static dissector_handle_t osi_tp_handle; +static dissector_handle_t tpkt_handle; + +#define DEFAULT_TPKT_PORT_RANGE "102" + +/* + * Check whether this could be a TPKT-encapsulated PDU. + * Returns -1 if it's not, and the PDU length from the TPKT header + * if it is. + * + * "min_len" is the minimum length of the PDU; the length field in the + * TPKT header must be at least "4+min_len" in order for this to be a + * valid TPKT PDU for the protocol in question. + */ +int +is_tpkt(tvbuff_t *tvb, int min_len) +{ + guint16 pkt_len; + + /* + * If TPKT is disabled, don't dissect it, just return -1, meaning + * "this isn't TPKT". + */ + if (!proto_is_protocol_enabled(proto_tpkt_ptr)) + return -1; + + /* There should at least be 4 bytes left in the frame */ + if (tvb_captured_length(tvb) < 4) + return -1; /* there aren't */ + + /* + * The first octet should be 3 and the second one should be 0 + * The H.323 implementers guide suggests that this might not + * always be the case.... + */ + if (!(tvb_get_guint8(tvb, 0) == 3 && tvb_get_guint8(tvb, 1) == 0)) + return -1; /* they're not */ + + /* + * Get the length from the TPKT header. Make sure it's large + * enough. + */ + pkt_len = tvb_get_ntohs(tvb, 2); + if (pkt_len < 4 + min_len) + return -1; /* it's not */ + + /* + * Return the length from the header. + */ + return pkt_len; +} +guint16 +is_asciitpkt(tvbuff_t *tvb) +{ + guint16 count; + /* + * If TPKT is disabled, don't dissect it, just return -1, meaning + * "this isn't TPKT". + */ + if (!proto_is_protocol_enabled(proto_tpkt_ptr)) + return -1; + + /* There should at least be 8 bytes left in the frame */ + if (!tvb_bytes_exist(tvb, 0, 8)) + return -1; /* there aren't */ + + /* + * The first four octets should be alphanumeric ASCII + */ + for (count = 0; count <=7 ; count ++) + { + if(!g_ascii_isalnum(tvb_get_guint8(tvb,count))) + { + return 0; + } + } + return 1; + + +} +static int +parseLengthText ( guint8* pTpktData ) +{ + int value = 0; + const guint8 * pData = pTpktData; + int bitvalue = 0, count1 = 3; + int count; + for (count = 0; count <= 3; count++) + { + if (('0' <= *(pData + count)) && (*(pData + count) <= '9')) + bitvalue = *(pData + count) - 48; + else if (('a' <= *(pData + count)) && (*(pData + count) <= 'f' )) + bitvalue = *(pData + count) - 87; + else if (('A' <= *(pData + count)) && (*(pData + count) <= 'F' )) + bitvalue = *(pData + count) - 55; + + value += bitvalue << (4*count1); + count1--; + } + return value; +} +static int +parseVersionText ( guint8* pTpktData ) +{ + int value = 0; + guint8 * pData = pTpktData; + int bitvalue = 0, count1 = 1; + int count; + for (count = 0; count <= 1; count++) + { + if (('0' <= *(pData + count)) && (*(pData + count) <= '9')) + bitvalue = *(pData + count) - 48; + else if (('a' <= *(pData + count)) && (*(pData + count) <= 'f' )) + bitvalue = *(pData + count) - 87; + else if (('A' <= *(pData + count)) && (*(pData + count) <= 'F' )) + bitvalue = *(pData + count) - 55; + + value += bitvalue << (4*count1); + count1--; + } + + return value; +} +static int +parseReservedText ( guint8* pTpktData ) +{ + int value = 0; + guint8 * pData = pTpktData; + int bitvalue = 0, count1 = 1; + int count; + for (count = 0; count <= 1; count++) + { + if (('0' <= *(pData + count)) && (*(pData + count) <= '9')) + bitvalue = *(pData + count) - 48; + else if (('a' <= *(pData + count)) && (*(pData + count) <= 'f' )) + bitvalue = *(pData + count) - 87; + else if (('A' <= *(pData + count)) && (*(pData + count) <= 'F' )) + bitvalue = *(pData + count) - 55; + + value += bitvalue << (4*count1); + count1--; + } + + return value; +} + +/* + * Length of the TPKT text-layer header. + */ +static const int TEXT_LAYER_LENGTH = 9; + +/* + * 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]; + + /* + * 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_clear(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_tree_add_item(tpkt_tree, hf_tpkt_continuation_data, tvb, offset, -1, ENC_NA); + } + 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_length_caplen(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. + */ + TRY { + call_dissector(subdissector_handle, next_tvb, pinfo, + tree); + } + CATCH_NONFATAL_ERRORS { + + show_exception(tvb, pinfo, tree, EXCEPT_CODE, GET_MESSAGE); + } + ENDTRY; + + /* + * Skip the payload. + */ + offset += data_len; + } +} + +/* + * Dissect TPKT-encapsulated data in a TCP stream. + */ +void +dissect_tpkt_encap(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, + gboolean desegment, 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 length; + tvbuff_t *volatile next_tvb; + const char *saved_proto; + heur_dtbl_entry_t *hdtbl_entry; + + /* + * 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 (desegment) + col_clear(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) != 3) { + /* + * 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. + */ + + if (dissector_try_heuristic(tpkt_heur_subdissector_list, tvb, + pinfo, proto_tree_get_root(tree), + &hdtbl_entry, NULL)) { + return; + } + + 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_tree_add_item(tpkt_tree, hf_tpkt_continuation_data, tvb, offset, -1, ENC_NA); + } + return; + } + + length_remaining = tvb_captured_length_remaining(tvb, offset); + + /* + * Can we do reassembly? + */ + if (desegment && pinfo->can_desegment) { + /* + * Yes - is the TPKT header split across segment + * boundaries? + */ + if (length_remaining < 4) { + /* + * Yes. Tell the TCP dissector where the data + * for this message starts in the data it + * handed us and that we need "some more data." + * Don't tell it exactly how many bytes we need + * because if/when we ask for even more (after + * the header) that will break reassembly. + */ + pinfo->desegment_offset = offset; + pinfo->desegment_len = DESEGMENT_ONE_MORE_SEGMENT; + return; + } + } + + /* + * Get the length from the TPKT header. + */ + data_len = tvb_get_ntohs(tvb, offset + 2); + + /* + * Can we do reassembly? + */ + if (desegment && pinfo->can_desegment) { + /* + * Yes - is the payload split across segment + * boundaries? + */ + if (length_remaining < data_len) { + /* + * Yes. Tell the TCP dissector where + * the data for this message starts in + * the data it handed us, and how many + * more bytes we need, and return. + */ + pinfo->desegment_offset = offset; + pinfo->desegment_len = + data_len - length_remaining; + return; + } + } + + /* + * 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 (!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, 4, ENC_NA); + tpkt_tree = proto_item_add_subtree(ti, ett_tpkt); + proto_item_set_text(ti, "TPKT"); + + /* Version */ + proto_tree_add_item(tpkt_tree, hf_tpkt_version, tvb, + offset, 1, ENC_BIG_ENDIAN); + proto_item_append_text(ti, ", Version: 3"); + + /* Reserved octet*/ + proto_tree_add_item(tpkt_tree, hf_tpkt_reserved, tvb, + offset + 1, 1, ENC_BIG_ENDIAN); + + /* Length */ + proto_tree_add_uint(tpkt_tree, hf_tpkt_length, tvb, + offset + 2, 2, data_len); + proto_item_append_text(ti, ", Length: %u", data_len); + } + pinfo->current_proto = saved_proto; + + /* Skip the TPKT header. */ + offset += 4; + data_len -= 4; + + /* + * Construct a tvbuff containing the amount of the payload + * we have available. Make its reported length the + * amount of data in this TPKT packet. + * + * XXX - if reassembly isn't enabled. the subdissector + * will throw a BoundsError exception, rather than a + * ReportedBoundsError exception. We really want + * a tvbuff where the length is "length", the reported + * length is "plen + 2", and the "if the snapshot length + * were infinite" length were the minimum of the + * reported length of the tvbuff handed to us and "plen+2", + * with a new type of exception thrown if the offset is + * within the reported length but beyond that third length, + * with that exception getting the "Unreassembled Packet" + * error. + */ + length = length_remaining - 4; + if (length > data_len) + length = data_len; + next_tvb = tvb_new_subset_length_caplen(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. + */ + TRY { + call_dissector(subdissector_handle, next_tvb, pinfo, + tree); + } + CATCH_NONFATAL_ERRORS { + show_exception(tvb, pinfo, tree, EXCEPT_CODE, GET_MESSAGE); + } + ENDTRY; + + /* + * Skip the payload. + */ + offset += length; + } +} + +/* + * Dissect RFC 1006 TPKT, which wraps a TPKT header around an OSI TP + * PDU. + */ +static int +dissect_tpkt(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_) +{ + dissect_tpkt_encap(tvb, pinfo, tree, tpkt_desegment, osi_tp_handle); + return tvb_captured_length(tvb); +} + +/* + * Dissect ASCII TPKT, which wraps a ASCII TPKT header around an OSI TP + * PDU. + */ +#if 0 +static int +dissect_ascii_tpkt(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_) +{ + dissect_asciitpkt(tvb, pinfo, tree, osi_tp_handle); + return tvb_captured_length(tvb); +} +#endif + +/* A heuristic dissector for TPKT. This is useful for RDP, where TLS may + * or may not be present depending on the RDP security settings. + */ +static int +dissect_tpkt_heur(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data) +{ + if (is_tpkt(tvb, 0) == -1) { + /* Doesn't look like TPKT directly. Might be over TLS, so reject + * and let the TLS heuristic dissector take a look + */ + return 0; + } + + return dissect_tpkt(tvb, pinfo, tree, data); +} + +void +proto_register_tpkt(void) +{ + static hf_register_info hf[] = { + { + &hf_tpkt_version, + { + "Version", + "tpkt.version", + FT_UINT8, + BASE_DEC, + NULL, + 0x0, + "Version, only version 3 is defined", HFILL + } + }, + { + &hf_tpkt_reserved, + { + "Reserved", + "tpkt.reserved", + FT_UINT8, + BASE_DEC, + NULL, + 0x0, + "Reserved, should be 0", HFILL + } + }, + { + &hf_tpkt_length, + { + "Length", + "tpkt.length", + FT_UINT16, + BASE_DEC, + NULL, + 0x0, + "Length of data unit, including this header", HFILL + } + }, + { + &hf_tpkt_continuation_data, + { + "Continuation data", + "tpkt.continuation_data", + FT_BYTES, + BASE_NONE, + NULL, + 0x0, + NULL, HFILL + } + }, + }; + + static gint *ett[] = + { + &ett_tpkt, + }; + module_t *tpkt_module; + + proto_tpkt = proto_register_protocol("TPKT - ISO on TCP - RFC1006", "TPKT", "tpkt"); + proto_tpkt_ptr = find_protocol_by_id(proto_tpkt); + proto_register_field_array(proto_tpkt, hf, array_length(hf)); + proto_register_subtree_array(ett, array_length(ett)); + tpkt_handle = register_dissector("tpkt", dissect_tpkt, proto_tpkt); + + tpkt_module = prefs_register_protocol(proto_tpkt, NULL); + prefs_register_bool_preference(tpkt_module, "desegment", + "Reassemble TPKT messages spanning multiple TCP segments", + "Whether the TPKT dissector should reassemble messages spanning multiple TCP segments. " + "To use this option, you must also enable \"Allow subdissectors to reassemble TCP streams\" in the TCP protocol settings.", + &tpkt_desegment); + + /* heuristic dissectors for premable CredSSP before RDP and Fast-Path RDP packets */ + tpkt_heur_subdissector_list = register_heur_dissector_list("tpkt", proto_tpkt); + + proto_tpkt_heur = proto_register_protocol_in_name_only("TPKT Heuristic (for RDP)", "TPKT Heuristic (for RDP)", "tpkt", proto_tpkt, FT_PROTOCOL); +} + +void +proto_reg_handoff_tpkt(void) +{ + osi_tp_handle = find_dissector("ositp"); + dissector_add_uint_range_with_preference("tcp.port", TCP_PORT_TPKT_RANGE, tpkt_handle); + + /* ssl_dissector_add registers TLS as the dissector for TCP for the + * given port. We can't use it, since on port 3389 TPKT (for RDP) can be + * over TLS or directly over TCP, depending on the RDP security settings. + * TPKT heuristics are also too weak to enable in general. Instead, + * use the heuristic dissector by default just on the RDP port, and + * if rejected the TLS heuristic dissector will be tried. + */ + dissector_add_uint("tls.port", TCP_PORT_RDP, tpkt_handle); + dissector_add_uint("tcp.port", TCP_PORT_RDP, create_dissector_handle(dissect_tpkt_heur, proto_tpkt_heur)); + heur_dissector_add("tcp", dissect_tpkt_heur, "TPKT over TCP", "tpkt_tcp", proto_tpkt, HEURISTIC_DISABLE); + + /* + tpkt_ascii_handle = create_dissector_handle(dissect_ascii_tpkt, proto_tpkt); + dissector_add_uint("tcp.port", TCP_PORT_TPKT, tpkt_ascii_handle); + */ + +} + +/* + * Editor modelines - https://www.wireshark.org/tools/modelines.html + * + * Local variables: + * c-basic-offset: 4 + * tab-width: 8 + * indent-tabs-mode: nil + * End: + * + * vi: set shiftwidth=4 tabstop=8 expandtab: + * :indentSize=4:tabSize=8:noTabs=true: + */ |