/* packet-dtcp-ip.c * Routines for DTCP-IP dissection * (Digital Transmission Content Protection over IP) * * Copyright 2012, Martin Kaiser * * Wireshark - Network traffic analyzer * By Gerald Combs * Copyright 1998 Gerald Combs * * SPDX-License-Identifier: GPL-2.0-or-later */ /* * quote from www.dtcp.com: * "DTCP is a method of protecting audio and audiovisual entertainment * content on home and personal networks over highbandwidth bidirectional * digital interfaces" * * this dissector supports DTCP on top of TCP/IP * for now, only the AKE (authentication and key exchange) * messages are implemented * * the dissector is based on the publicly available (informative) specifications * obtained from http://www.dtcp.com/specifications.aspx * (complete specifications are available only to licensees) */ #include "config.h" #include static int proto_dtcp_ip; void proto_register_dtcp_ip(void); void proto_reg_handoff_dtcp_ip(void); static dissector_handle_t dtcp_ip_handle; static int ett_dtcp_ip; static int ett_dtcp_ip_ctrl; static int ett_dtcp_ip_ake_procedure; static int hf_dtcp_ip_type; static int hf_dtcp_ip_length; static int hf_dtcp_ip_ctype; static int hf_dtcp_ip_category; static int hf_dtcp_ip_ake_id; static int hf_dtcp_ip_subfct; static int hf_dtcp_ip_ake_procedure; static int hf_dtcp_ip_ake_proc_full; static int hf_dtcp_ip_ake_proc_ex_full; static int hf_dtcp_ip_ake_xchg_key; static int hf_dtcp_ip_subfct_dep; static int hf_dtcp_ip_ake_label; static int hf_dtcp_ip_number; static int hf_dtcp_ip_status; static int hf_dtcp_ip_ake_info; #define CTRL_LEN 8 /* control block is 8 bytes long */ /* these definitions are taken from the public DTCP specification it sounds like the private version defines more subfunctions */ static const value_string subfct[] = { { 0x01, "challenge" }, { 0x02, "response" }, { 0x03, "exchange_key" }, { 0, NULL } }; static int * const ake_procedure_fields[] = { /* must be int, not int */ &hf_dtcp_ip_ake_proc_full, &hf_dtcp_ip_ake_proc_ex_full, NULL }; /* only one bit may be set in exchange_key, we can use a value string */ static const value_string xchg_key[] = { { 0x00, "None" }, { 0x08, "Exchange key (K_X) for AES-128" }, { 0x20, "Session Exchange key (K_S) for AES-128" }, { 0x40, "Remote Exchange key (K_R) for AES-128" }, { 0, NULL } }; static const value_string ctrl_status[] = { { 0x0, "No error" }, { 0x1, "Support for no more authentication procedures is currently available" }, { 0x7, "Any other error" }, { 0xF, "No information" }, { 0, NULL } }; /* check if the packet is actually DTCP-IP */ static bool dtcp_ip_check_packet(tvbuff_t *tvb) { unsigned offset = 0; uint8_t type; uint16_t length; /* a minimum DTCP-IP AKE packet has Type (1 byte), Length (2 bytes) and Control (8 bytes) */ if (tvb_reported_length(tvb) < 1+2+CTRL_LEN) return false; type = tvb_get_uint8(tvb, offset); /* all DTCP-IP AKE packets have type 1 */ if (type != 1) return false; offset++; /* length field is length of the control block + length of ake_info */ length = tvb_get_ntohs(tvb, offset); if (length < CTRL_LEN) return false; return true; } static int dissect_dtcp_ip(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_) { unsigned offset = 0; uint16_t length; proto_item *pi; proto_tree *dtcp_ip_tree, *dtcp_ip_ctrl_tree; uint8_t subfct_val; const char *subfct_str; int ake_info_len; if (!dtcp_ip_check_packet(tvb)) return 0; /* not a DTCP-IP packet */ col_set_str(pinfo->cinfo, COL_PROTOCOL, "DTCP-IP"); col_clear(pinfo->cinfo, COL_INFO); pi = proto_tree_add_protocol_format(tree, proto_dtcp_ip, tvb, 0, -1, "DTCP-IP"); dtcp_ip_tree = proto_item_add_subtree(pi, ett_dtcp_ip); proto_tree_add_item(dtcp_ip_tree, hf_dtcp_ip_type, tvb, offset, 1, ENC_BIG_ENDIAN); offset++; length = tvb_get_ntohs(tvb, 1); /* overall packet length is 1 byte for tag + 2 bytes for length field + the value encoded in the length field */ proto_item_set_len(pi, 1+2+length); proto_tree_add_item(dtcp_ip_tree, hf_dtcp_ip_length, tvb, offset, 2, ENC_BIG_ENDIAN); offset += 2; dtcp_ip_ctrl_tree = proto_tree_add_subtree(dtcp_ip_tree, tvb, offset, CTRL_LEN, ett_dtcp_ip_ctrl, NULL, "Control"); /* for now, we don't display the 4 reserved bits */ proto_tree_add_item(dtcp_ip_ctrl_tree, hf_dtcp_ip_ctype, tvb, offset, 1, ENC_BIG_ENDIAN); offset++; proto_tree_add_item(dtcp_ip_ctrl_tree, hf_dtcp_ip_category, tvb, offset, 1, ENC_BIG_ENDIAN); proto_tree_add_item(dtcp_ip_ctrl_tree, hf_dtcp_ip_ake_id, tvb, offset, 1, ENC_BIG_ENDIAN); offset++; subfct_val = tvb_get_uint8(tvb, offset); subfct_str = val_to_str_const(subfct_val, subfct, "unknown"); col_append_sep_fstr(pinfo->cinfo, COL_INFO, NULL, "%s (0x%x)", subfct_str, subfct_val); proto_tree_add_item(dtcp_ip_ctrl_tree, hf_dtcp_ip_subfct, tvb, offset, 1, ENC_BIG_ENDIAN); offset++; proto_tree_add_bitmask(dtcp_ip_ctrl_tree, tvb, offset, hf_dtcp_ip_ake_procedure, ett_dtcp_ip_ake_procedure, ake_procedure_fields, ENC_BIG_ENDIAN); offset++; proto_tree_add_item(dtcp_ip_ctrl_tree, hf_dtcp_ip_ake_xchg_key, tvb, offset, 1, ENC_BIG_ENDIAN); offset++; proto_tree_add_item(dtcp_ip_ctrl_tree, hf_dtcp_ip_subfct_dep, tvb, offset, 1, ENC_BIG_ENDIAN); offset++; proto_tree_add_item(dtcp_ip_ctrl_tree, hf_dtcp_ip_ake_label, tvb, offset, 1, ENC_BIG_ENDIAN); offset++; proto_tree_add_item(dtcp_ip_ctrl_tree, hf_dtcp_ip_number, tvb, offset, 1, ENC_BIG_ENDIAN); proto_tree_add_item(dtcp_ip_ctrl_tree, hf_dtcp_ip_status, tvb, offset, 1, ENC_BIG_ENDIAN); offset++; ake_info_len = length-CTRL_LEN; if (ake_info_len > 0) { proto_tree_add_item(dtcp_ip_tree, hf_dtcp_ip_ake_info, tvb, offset, ake_info_len, ENC_NA); offset += (unsigned)ake_info_len; } return offset; } void proto_register_dtcp_ip(void) { static hf_register_info hf[] = { { &hf_dtcp_ip_type, { "Type", "dtcp-ip.type", FT_UINT8, BASE_HEX, NULL, 0, NULL, HFILL } }, { &hf_dtcp_ip_length, { "Length", "dtcp-ip.length", FT_UINT16, BASE_DEC, NULL, 0, NULL, HFILL } }, /* it seems that / is not allowed in a filter name ... */ { &hf_dtcp_ip_ctype, { "ctype/response", "dtcp-ip.ctrl.ctype_response", FT_UINT8, BASE_HEX, NULL, 0x0F, NULL, HFILL } }, { &hf_dtcp_ip_category, { "Category", "dtcp-ip.ctrl.category", FT_UINT8, BASE_HEX, NULL, 0xF0, NULL, HFILL } }, { &hf_dtcp_ip_ake_id, { "AKE_ID", "dtcp-ip.ctrl.ake_id", FT_UINT8, BASE_HEX, NULL, 0x0F, NULL, HFILL } }, { &hf_dtcp_ip_subfct, { "Subfunction", "dtcp-ip.ctrl.subfunction", FT_UINT8, BASE_HEX, VALS(subfct), 0, NULL, HFILL } }, { &hf_dtcp_ip_ake_procedure, { "AKE_procedure", "dtcp-ip.ctrl.ake_procedure", FT_UINT8, BASE_HEX, NULL, 0, NULL, HFILL } }, /* 8 is the bit witdh of the field */ { &hf_dtcp_ip_ake_proc_full, { "Full Authentication procedure", "dtcp-ip.ctrl.ake_procedure.full_auth", FT_BOOLEAN, 8, NULL, 0x04, NULL, HFILL } }, { &hf_dtcp_ip_ake_proc_ex_full, { "Extended Full Authentication procedure", "dtcp-ip.ctrl.ake_procedure.ex_full_auth", FT_BOOLEAN, 8, NULL, 0x08, NULL, HFILL } }, { &hf_dtcp_ip_ake_xchg_key, { "exchange_key", "dtcp-ip.ctrl.exchange_key", FT_UINT8, BASE_HEX, VALS(xchg_key), 0, NULL, HFILL } }, { &hf_dtcp_ip_subfct_dep, { "subfunction_dependent", "dtcp-ip.ctrl.subfunction_dependent", FT_UINT8, BASE_HEX, NULL, 0, NULL, HFILL } }, { &hf_dtcp_ip_ake_label, { "AKE_label", "dtcp-ip.ctrl.ake_label", FT_UINT8, BASE_HEX, NULL, 0, NULL, HFILL } }, { &hf_dtcp_ip_number, { "number", "dtcp-ip.ctrl.number", FT_UINT8, BASE_HEX, NULL, 0xF0, NULL, HFILL } }, { &hf_dtcp_ip_status, { "Status", "dtcp-ip.ctrl.status", FT_UINT8, BASE_HEX, VALS(ctrl_status), 0x0F, NULL, HFILL } }, { &hf_dtcp_ip_ake_info, { "AKE_Info", "dtcp-ip.ake_info", FT_BYTES, BASE_NONE, NULL, 0, NULL, HFILL } } }; static int *ett[] = { &ett_dtcp_ip, &ett_dtcp_ip_ctrl, &ett_dtcp_ip_ake_procedure }; proto_dtcp_ip = proto_register_protocol("Digital Transmission Content Protection over IP", "DTCP-IP", "dtcp-ip"); proto_register_field_array(proto_dtcp_ip, hf, array_length(hf)); proto_register_subtree_array(ett, array_length(ett)); dtcp_ip_handle = register_dissector("dtcp-ip", dissect_dtcp_ip, proto_dtcp_ip); } void proto_reg_handoff_dtcp_ip(void) { dissector_add_for_decode_as_with_preference("tcp.port", dtcp_ip_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: */