diff options
Diffstat (limited to 'epan/dissectors/packet-gsm_rlp.c')
| -rw-r--r-- | epan/dissectors/packet-gsm_rlp.c | 333 |
1 files changed, 333 insertions, 0 deletions
diff --git a/epan/dissectors/packet-gsm_rlp.c b/epan/dissectors/packet-gsm_rlp.c new file mode 100644 index 0000000000..f4c9a4f3ed --- /dev/null +++ b/epan/dissectors/packet-gsm_rlp.c @@ -0,0 +1,333 @@ +/* packet-gsm_rlp.c + * Routines for GSM RLP (3GPP TS 24.022) frame dissection + * (C) 2023 Harald Welte <laforge@osmocom.org> + * + * Wireshark - Network traffic analyzer + * By Gerald Combs <gerald@wireshark.org> + * Copyright 1998 + * + * SPDX-License-Identifier: GPL-2.0-or-later + */ + +#include "config.h" + +#include <epan/packet.h> +#include <epan/prefs.h> +#include <epan/expert.h> +#include <epan/reassemble.h> +#include <epan/conversation.h> + +void proto_register_gsmrlp(void); + +static int proto_gsmrlp = -1; + +static int hf_gsmrlp_cr = -1; +static int hf_gsmrlp_pf = -1; +static int hf_gsmrlp_n_r = -1; +static int hf_gsmrlp_n_s = -1; +static int hf_gsmrlp_ftype = -1; +static int hf_gsmrlp_s_ftype = -1; +static int hf_gsmrlp_u_ftype = -1; +static int hf_gsmrlp_fcs = -1; +static int hf_gsmrlp_fcs_status = -1; + +static int hf_gsmrlp_xid_p_type = -1; +static int hf_gsmrlp_xid_p_len = -1; +static int hf_gsmrlp_xid_p_val = -1; + +static int ett_gsmrlp = -1; +static int ett_gsmrlp_xid = -1; + +static expert_field ei_gsmrlp_fcs_bad = EI_INIT; + +/* 3GPP TS 24.002 Section 5.2.1 */ +enum rlp_ftype { + RLP_FT_U, + RLP_FT_S, + RLP_FT_IS, +}; + +static const value_string rlp_ftype_vals[] = { + { RLP_FT_U, "U" }, + { RLP_FT_S, "S" }, + { RLP_FT_IS, "IS" }, + { 0, NULL } +}; + +/* 3GPP TS 24.002 Section 5.2.1 */ +enum rlp_u_ftype { + RLP_U_FT_SABM = 0x07, + RLP_U_FT_UA = 0x0c, + RLP_U_FT_DISC = 0x08, + RLP_U_FT_DM = 0x03, + RLP_U_FT_NULL = 0x0f, + RLP_U_FT_UI = 0x00, + RLP_U_FT_XID = 0x17, + RLP_U_FT_TEST = 0x1c, + RLP_U_FT_REMAP = 0x11, +}; +static const value_string rlp_ftype_u_vals[] = { + { RLP_U_FT_SABM, "SABM" }, + { RLP_U_FT_UA, "UA" }, + { RLP_U_FT_DISC, "DISC" }, + { RLP_U_FT_DM, "DM" }, + { RLP_U_FT_NULL, "NULL" }, + { RLP_U_FT_UI, "UI" }, + { RLP_U_FT_XID, "XID" }, + { RLP_U_FT_TEST, "TEST" }, + { RLP_U_FT_REMAP, "REMAP" }, + { 0, NULL } +}; + +/* 3GPP TS 24.002 Section 5.2.1 */ +enum rlp_s_ftype { + RLP_S_FT_RR = 0, + RLP_S_FT_REJ = 2, + RLP_S_FT_RNR = 1, + RLP_S_FT_SREJ = 3, +}; +static const value_string rlp_ftype_s_vals[] = { + { RLP_S_FT_RR, "RR" }, + { RLP_S_FT_REJ, "REJ" }, + { RLP_S_FT_RNR, "RNR" }, + { RLP_S_FT_SREJ, "SREJ" }, + { 0, NULL } +}; + +/* 3GPP TS 24.002 Section 5.2.2.6 */ +enum rlp_xid_param_type { + XID_P_DELIMITER = 0, + XID_P_RLP_VERSION = 1, + XID_P_IWF_TO_UE_WIN_SIZE = 2, + XID_P_UE_TO_IWF_WIN_SIZE = 3, + XID_P_ACK_TIMER_T1 = 4, + XID_P_RETRANS_ATTEMPTS_N2 = 5, + XID_P_REPLY_DELAY_T2 = 6, + XID_P_COMPRESSION_PT = 7, + XID_P_RESEQUENCING_T4 = 8, + XID_P_OPTIONAL_FEATURES = 9, +}; + +static const value_string rlp_xid_param_vals[] = { + { XID_P_DELIMITER, "Delimiter (end of parameters)" }, + { XID_P_RLP_VERSION, "RLP version number" }, + { XID_P_IWF_TO_UE_WIN_SIZE, "IWF to UE window size" }, + { XID_P_UE_TO_IWF_WIN_SIZE, "UE to IWF window size" }, + { XID_P_ACK_TIMER_T1, "Acknowledgement Timer (T1)" }, + { XID_P_RETRANS_ATTEMPTS_N2, "Retransmission attempts (N2)" }, + { XID_P_REPLY_DELAY_T2, "Reply delay (T2)" }, + { XID_P_COMPRESSION_PT, "Compression PT" }, + { XID_P_RESEQUENCING_T4, "Re-sequencing timer (T4)" }, + { XID_P_OPTIONAL_FEATURES, "Optional Features" }, + { 0, NULL } +}; + +static const guint32 rlp_fcs_table[256] = { + 0x00B29D2D, 0x00643A5B, 0x0044D87A, 0x00927F0C, 0x00051C38, 0x00D3BB4E, 0x00F3596F, 0x0025FE19, + 0x008694BC, 0x005033CA, 0x0070D1EB, 0x00A6769D, 0x003115A9, 0x00E7B2DF, 0x00C750FE, 0x0011F788, + 0x00DA8E0F, 0x000C2979, 0x002CCB58, 0x00FA6C2E, 0x006D0F1A, 0x00BBA86C, 0x009B4A4D, 0x004DED3B, + 0x00EE879E, 0x003820E8, 0x0018C2C9, 0x00CE65BF, 0x0059068B, 0x008FA1FD, 0x00AF43DC, 0x0079E4AA, + 0x0062BB69, 0x00B41C1F, 0x0094FE3E, 0x00425948, 0x00D53A7C, 0x00039D0A, 0x00237F2B, 0x00F5D85D, + 0x0056B2F8, 0x0080158E, 0x00A0F7AF, 0x007650D9, 0x00E133ED, 0x0037949B, 0x001776BA, 0x00C1D1CC, + 0x000AA84B, 0x00DC0F3D, 0x00FCED1C, 0x002A4A6A, 0x00BD295E, 0x006B8E28, 0x004B6C09, 0x009DCB7F, + 0x003EA1DA, 0x00E806AC, 0x00C8E48D, 0x001E43FB, 0x008920CF, 0x005F87B9, 0x007F6598, 0x00A9C2EE, + 0x0049DA1E, 0x009F7D68, 0x00BF9F49, 0x0069383F, 0x00FE5B0B, 0x0028FC7D, 0x00081E5C, 0x00DEB92A, + 0x007DD38F, 0x00AB74F9, 0x008B96D8, 0x005D31AE, 0x00CA529A, 0x001CF5EC, 0x003C17CD, 0x00EAB0BB, + 0x0021C93C, 0x00F76E4A, 0x00D78C6B, 0x00012B1D, 0x00964829, 0x0040EF5F, 0x00600D7E, 0x00B6AA08, + 0x0015C0AD, 0x00C367DB, 0x00E385FA, 0x0035228C, 0x00A241B8, 0x0074E6CE, 0x005404EF, 0x0082A399, + 0x0099FC5A, 0x004F5B2C, 0x006FB90D, 0x00B91E7B, 0x002E7D4F, 0x00F8DA39, 0x00D83818, 0x000E9F6E, + 0x00ADF5CB, 0x007B52BD, 0x005BB09C, 0x008D17EA, 0x001A74DE, 0x00CCD3A8, 0x00EC3189, 0x003A96FF, + 0x00F1EF78, 0x0027480E, 0x0007AA2F, 0x00D10D59, 0x00466E6D, 0x0090C91B, 0x00B02B3A, 0x00668C4C, + 0x00C5E6E9, 0x0013419F, 0x0033A3BE, 0x00E504C8, 0x007267FC, 0x00A4C08A, 0x008422AB, 0x005285DD, + 0x001F18F0, 0x00C9BF86, 0x00E95DA7, 0x003FFAD1, 0x00A899E5, 0x007E3E93, 0x005EDCB2, 0x00887BC4, + 0x002B1161, 0x00FDB617, 0x00DD5436, 0x000BF340, 0x009C9074, 0x004A3702, 0x006AD523, 0x00BC7255, + 0x00770BD2, 0x00A1ACA4, 0x00814E85, 0x0057E9F3, 0x00C08AC7, 0x00162DB1, 0x0036CF90, 0x00E068E6, + 0x00430243, 0x0095A535, 0x00B54714, 0x0063E062, 0x00F48356, 0x00222420, 0x0002C601, 0x00D46177, + 0x00CF3EB4, 0x001999C2, 0x00397BE3, 0x00EFDC95, 0x0078BFA1, 0x00AE18D7, 0x008EFAF6, 0x00585D80, + 0x00FB3725, 0x002D9053, 0x000D7272, 0x00DBD504, 0x004CB630, 0x009A1146, 0x00BAF367, 0x006C5411, + 0x00A72D96, 0x00718AE0, 0x005168C1, 0x0087CFB7, 0x0010AC83, 0x00C60BF5, 0x00E6E9D4, 0x00304EA2, + 0x00932407, 0x00458371, 0x00656150, 0x00B3C626, 0x0024A512, 0x00F20264, 0x00D2E045, 0x00044733, + 0x00E45FC3, 0x0032F8B5, 0x00121A94, 0x00C4BDE2, 0x0053DED6, 0x008579A0, 0x00A59B81, 0x00733CF7, + 0x00D05652, 0x0006F124, 0x00261305, 0x00F0B473, 0x0067D747, 0x00B17031, 0x00919210, 0x00473566, + 0x008C4CE1, 0x005AEB97, 0x007A09B6, 0x00ACAEC0, 0x003BCDF4, 0x00ED6A82, 0x00CD88A3, 0x001B2FD5, + 0x00B84570, 0x006EE206, 0x004E0027, 0x0098A751, 0x000FC465, 0x00D96313, 0x00F98132, 0x002F2644, + 0x00347987, 0x00E2DEF1, 0x00C23CD0, 0x00149BA6, 0x0083F892, 0x00555FE4, 0x0075BDC5, 0x00A31AB3, + 0x00007016, 0x00D6D760, 0x00F63541, 0x00209237, 0x00B7F103, 0x00615675, 0x0041B454, 0x00971322, + 0x005C6AA5, 0x008ACDD3, 0x00AA2FF2, 0x007C8884, 0x00EBEBB0, 0x003D4CC6, 0x001DAEE7, 0x00CB0991, + 0x00686334, 0x00BEC442, 0x009E2663, 0x00488115, 0x00DFE221, 0x00094557, 0x0029A776, 0x00FF0000 +}; + +/*! compute RLP FCS according to 3GPP TS 24.022 Section 4.4 */ +static guint32 rlp_fcs_compute(const guchar *in, size_t in_len) +{ + guint32 divider = 0; + size_t i; + + for (i = 0; i < in_len; i++) { + guchar input = in[i] ^ (divider & 0xff); + divider = (divider >> 8) ^ rlp_fcs_table[input]; + } + + return ((divider & 0xff) << 16) | (divider & 0xff00) | ((divider & 0xff0000) >> 16); +} + +static int +dissect_gsmrlp_xid(tvbuff_t *tvb, gint offset, packet_info *pinfo _U_, proto_tree *tree) +{ + gint cur; + + for (cur = offset; cur < (gint) tvb_reported_length(tvb);) { + guint8 len = tvb_get_guint8(tvb, cur) & 0x0f; + guint8 type = tvb_get_guint8(tvb, cur) >> 4; + proto_tree *xid_tree; + + proto_tree_add_subtree_format(tree, tvb, cur, 1 + len, ett_gsmrlp_xid, &xid_tree, "XID Parameter: %s", + val_to_str(type, rlp_xid_param_vals, "Unknown")); + proto_tree_add_item(xid_tree, hf_gsmrlp_xid_p_type, tvb, cur, 1, ENC_BIG_ENDIAN); + proto_tree_add_item(xid_tree, hf_gsmrlp_xid_p_len, tvb, cur, 1, ENC_BIG_ENDIAN); + if (len) + proto_tree_add_item(xid_tree, hf_gsmrlp_xid_p_val, tvb, cur + 1, len, ENC_BIG_ENDIAN); + cur += 1 + len; + if (type == XID_P_DELIMITER) + break; + } + + return cur - offset; +} + + +/* Dissect a RLP v0/v1 message as described in TS 24.022 section 5.2 */ +static int +dissect_gsmrlp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void* data _U_) +{ + int reported_len = tvb_reported_length(tvb); + proto_tree *rlp_tree; + proto_item *ti; + guint8 n_s, n_r; + + /* we currently support the 16bit header of RLP v0 + v1 */ + + col_set_str(pinfo->cinfo, COL_PROTOCOL, "GSM-RLP"); + + n_s = (tvb_get_guint8(tvb, 0)) >> 3 | ((tvb_get_guint8(tvb, 1) & 1) << 5); + n_r = (tvb_get_guint8(tvb, 1) >> 2); + + ti = proto_tree_add_protocol_format(tree, proto_gsmrlp, tvb, 0, reported_len, + "GSM RLP"); + rlp_tree = proto_item_add_subtree(ti, ett_gsmrlp); + + proto_tree_add_item(rlp_tree, hf_gsmrlp_cr, tvb, 0, 1, ENC_BIG_ENDIAN); + proto_tree_add_item(rlp_tree, hf_gsmrlp_pf, tvb, 1, 1, ENC_BIG_ENDIAN); + if (n_s == 0x3f) { /* U frame */ + guint u_ftype; + proto_tree_add_uint(rlp_tree, hf_gsmrlp_ftype, tvb, 0, 1, RLP_FT_U); + proto_tree_add_item_ret_uint(rlp_tree, hf_gsmrlp_u_ftype, tvb, 1, 1, ENC_BIG_ENDIAN, &u_ftype); + if ((n_r & 0x1f) == RLP_U_FT_XID) + dissect_gsmrlp_xid(tvb, 2, pinfo, rlp_tree); + proto_item_append_text(ti, " U-Frame: %s", val_to_str(u_ftype, rlp_ftype_u_vals, "Unknown 0x%02x")); + } else if (n_s == 0x3e) { /* S Frame */ + guint s_ftype; + proto_tree_add_uint(rlp_tree, hf_gsmrlp_ftype, tvb, 0, 1, RLP_FT_S); + proto_tree_add_item_ret_uint(rlp_tree, hf_gsmrlp_s_ftype, tvb, 0, 1, ENC_BIG_ENDIAN, &s_ftype); + proto_tree_add_uint(rlp_tree, hf_gsmrlp_n_r, tvb, 1, 1, n_r); + proto_item_append_text(ti, " S-Frame: %s, N(S): %u, N(R): %u", + val_to_str(s_ftype, rlp_ftype_s_vals, "Unknown 0x%02x"), n_s, n_r); + } else { /* IS Frame */ + tvbuff_t *next_tvb; + guint s_ftype; + int data_len; + + proto_tree_add_uint(rlp_tree, hf_gsmrlp_ftype, tvb, 0, 1, RLP_FT_IS); + proto_tree_add_item_ret_uint(rlp_tree, hf_gsmrlp_s_ftype, tvb, 0, 1, ENC_BIG_ENDIAN, &s_ftype); + proto_tree_add_uint(rlp_tree, hf_gsmrlp_n_s, tvb, 0, 2, n_s); + proto_tree_add_uint(rlp_tree, hf_gsmrlp_n_r, tvb, 1, 1, n_r); + proto_item_append_text(ti, " IS-Frame: %s, N(S): %u, N(R): %u", + val_to_str(s_ftype, rlp_ftype_s_vals, "Unknown 0x%02x"), n_s, n_r); + + /* dispatch user data */ + data_len = reported_len - 2 /* header */ - 3 /* FCS */; + next_tvb = tvb_new_subset_length(tvb, 2, data_len); + call_data_dissector(next_tvb, pinfo, rlp_tree); + } + + /* FCS is always the last 3 bytes of the message */ + guint32 fcs_computed = rlp_fcs_compute(tvb_get_ptr(tvb, 0, reported_len - 3), reported_len - 3); + proto_tree_add_checksum(rlp_tree, tvb, reported_len - 3, hf_gsmrlp_fcs, hf_gsmrlp_fcs_status, + &ei_gsmrlp_fcs_bad, pinfo, fcs_computed, ENC_BIG_ENDIAN, PROTO_CHECKSUM_VERIFY); + + return tvb_reported_length(tvb); +} + +void +proto_register_gsmrlp(void) +{ + static hf_register_info hf[] = { + { &hf_gsmrlp_cr, + { "C/R", "gsm_rlp.cr", FT_UINT8, BASE_DEC, NULL, 0x01, + "Command/Response bit", HFILL }}, + { &hf_gsmrlp_pf, + { "P/F", "gsm_rlp.pf", FT_UINT8, BASE_DEC, NULL, 0x02, + "Poll/Final bit", HFILL }}, + { &hf_gsmrlp_n_r, + { "N(R)", "gsm_rlp.n_r", FT_UINT8, BASE_DEC, NULL, 0, + "Receive Sequence Number", HFILL }}, + { &hf_gsmrlp_n_s, + { "N(S)", "gsm_rlp.n_s", FT_UINT8, BASE_DEC, NULL, 0, + "Send Sequence Number", HFILL }}, + { &hf_gsmrlp_ftype, + { "Frame type", "gsm_rlp.ftype", FT_UINT8, BASE_HEX, + VALS(rlp_ftype_vals), 0, NULL, HFILL }}, + { &hf_gsmrlp_u_ftype, + { "U Frame type", "gsm_rlp.u_ftype", FT_UINT8, BASE_HEX, + VALS(rlp_ftype_u_vals), 0x7c, NULL, HFILL }}, + { &hf_gsmrlp_s_ftype, + { "S frame type", "gsm_rlp.s_ftype", FT_UINT8, BASE_HEX, + VALS(rlp_ftype_s_vals), 0x06, NULL, HFILL }}, + { &hf_gsmrlp_fcs, + { "Frame Check Sequence", "gsm_rlp.fcs", FT_UINT24, BASE_HEX, + NULL, 0, NULL, HFILL }}, + { &hf_gsmrlp_fcs_status, + { "FCS Status", "gsm_rlp.fcs.status", FT_UINT8, BASE_NONE, + VALS(proto_checksum_vals), 0, NULL, HFILL }}, + + { &hf_gsmrlp_xid_p_type, + { "XID Parameter Type", "gsm_rlp.xid.param_type", FT_UINT8, BASE_HEX, + VALS(rlp_xid_param_vals), 0xf0, NULL, HFILL }}, + { &hf_gsmrlp_xid_p_len, + { "XID Parameter Length", "gsm_rlp.xid.param_len", FT_UINT8, BASE_DEC, + NULL, 0x0f, NULL, HFILL }}, + { &hf_gsmrlp_xid_p_val, + { "XID Parameter Value", "gsm_rlp.xid.param_value", FT_UINT8, BASE_DEC, + NULL, 0, NULL, HFILL }}, + }; + static gint *ett[] = { + &ett_gsmrlp, + &ett_gsmrlp_xid, + }; + static ei_register_info ei[] = { + { &ei_gsmrlp_fcs_bad, { "gsm_rlp.fcs_bad", PI_CHECKSUM, PI_ERROR, "Bad checksum" , EXPFILL }}, + }; + module_t *rlp_module; + expert_module_t *expert_gsmrlp; + + proto_gsmrlp = proto_register_protocol("GSM Radio Link Protocol (RLP)", "GSM-RLP", "gsm_rlp"); + proto_register_field_array(proto_gsmrlp, hf, array_length(hf)); + proto_register_subtree_array(ett, array_length(ett)); + expert_gsmrlp = expert_register_protocol(proto_gsmrlp); + expert_register_field_array(expert_gsmrlp, ei, array_length(ei)); + + register_dissector("gsm_rlp", dissect_gsmrlp, proto_gsmrlp); +} + +/* + * 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: + */ |