/* xdlc.c * Routines for use by various SDLC-derived protocols, such as HDLC * and its derivatives LAPB, IEEE 802.2 LLC, etc.. * * Wireshark - Network traffic analyzer * By Gerald Combs * Copyright 1998 Gerald Combs * * SPDX-License-Identifier: GPL-2.0-or-later */ #include "config.h" #include #include #include #include #include #include const value_string ftype_vals[] = { { XDLC_I, "Information frame" }, { XDLC_S, "Supervisory frame" }, { XDLC_U, "Unnumbered frame" }, { 0, NULL } }; const value_string stype_vals[] = { { XDLC_RR>>2, "Receiver ready" }, { XDLC_RNR>>2, "Receiver not ready" }, { XDLC_REJ>>2, "Reject" }, { XDLC_SREJ>>2, "Selective reject" }, { 0, NULL } }; static const value_string modifier_short_vals_cmd[] = { { XDLC_UI, "UI" }, { XDLC_UP, "UP" }, { XDLC_DISC, "DISC" }, { XDLC_UA, "UA" }, { XDLC_SNRM, "SNRM" }, { XDLC_SNRME, "SNRME" }, { XDLC_TEST, "TEST" }, { XDLC_SIM, "SIM" }, { XDLC_FRMR, "FRMR" }, { XDLC_CFGR, "CFGR" }, { XDLC_SARM, "SARM" }, { XDLC_SABM, "SABM" }, { XDLC_SARME, "SARME" }, { XDLC_SABME, "SABME" }, { XDLC_RESET, "RESET" }, { XDLC_XID, "XID" }, { XDLC_SNRME, "SNRME" }, { XDLC_BCN, "BCN" }, { 0, NULL } }; const value_string modifier_vals_cmd[] = { { XDLC_UI>>2, "Unnumbered Information" }, { XDLC_UP>>2, "Unnumbered Poll" }, { XDLC_DISC>>2, "Disconnect" }, { XDLC_UA>>2, "Unnumbered Acknowledge" }, { XDLC_SNRM>>2, "Set Normal Response Mode" }, { XDLC_TEST>>2, "Test" }, { XDLC_SIM>>2, "Set Initialization Mode" }, { XDLC_FRMR>>2, "Frame reject" }, { XDLC_CFGR>>2, "Configure" }, { XDLC_SARM>>2, "Set Asynchronous Response Mode" }, { XDLC_SABM>>2, "Set Asynchronous Balanced Mode" }, { XDLC_SARME>>2, "Set Asynchronous Response Mode Extended" }, { XDLC_SABME>>2, "Set Asynchronous Balanced Mode Extended" }, { XDLC_RESET>>2, "Reset" }, { XDLC_XID>>2, "Exchange identification" }, { XDLC_SNRME>>2, "Set Normal Response Mode Extended" }, { XDLC_BCN>>2, "Beacon" }, { 0, NULL } }; static const value_string modifier_short_vals_resp[] = { { XDLC_UI, "UI" }, { XDLC_UP, "UP" }, { XDLC_RD, "RD" }, { XDLC_UA, "UA" }, { XDLC_SNRM, "SNRM" }, { XDLC_TEST, "TEST" }, { XDLC_RIM, "RIM" }, { XDLC_FRMR, "FRMR" }, { XDLC_CFGR, "CFGR" }, { XDLC_DM, "DM" }, { XDLC_SABM, "SABM" }, { XDLC_SARME, "SARME" }, { XDLC_SABME, "SABME" }, { XDLC_RESET, "RESET" }, { XDLC_XID, "XID" }, { XDLC_SNRME, "SNRME" }, { XDLC_BCN, "BCN" }, { 0, NULL } }; const value_string modifier_vals_resp[] = { { XDLC_UI>>2, "Unnumbered Information" }, { XDLC_UP>>2, "Unnumbered Poll" }, { XDLC_RD>>2, "Request Disconnect" }, { XDLC_UA>>2, "Unnumbered Acknowledge" }, { XDLC_SNRM>>2, "Set Normal Response Mode" }, { XDLC_TEST>>2, "Test" }, { XDLC_RIM>>2, "Request Initialization Mode" }, { XDLC_FRMR>>2, "Frame reject" }, { XDLC_CFGR>>2, "Configure" }, { XDLC_DM>>2, "Disconnected mode" }, { XDLC_SABM>>2, "Set Asynchronous Balanced Mode" }, { XDLC_SARME>>2, "Set Asynchronous Response Mode Extended" }, { XDLC_SABME>>2, "Set Asynchronous Balanced Mode Extended" }, { XDLC_RESET>>2, "Reset" }, { XDLC_XID>>2, "Exchange identification" }, { XDLC_SNRME>>2, "Set Normal Response Mode Extended" }, { XDLC_BCN>>2, "Beacon" }, { 0, NULL } }; int get_xdlc_control(const uint8_t *pd, int offset, bool is_extended) { uint16_t control; switch (pd[offset] & 0x03) { case XDLC_S: default: /* * Supervisory or Information frame. */ if (is_extended) control = pletoh16(&pd[offset]); else control = pd[offset]; break; case XDLC_U: /* * Unnumbered frame. * * XXX - is this two octets, with a P/F bit, in HDLC extended * operation? It's one octet in LLC, even though the control * field of I and S frames is a 2-byte extended-operation field * in LLC. Given that there are no sequence numbers in the * control field of a U frame, there doesn't appear to be any * need for it to be 2 bytes in extended operation. */ control = pd[offset]; break; } return control; } int dissect_xdlc_control(tvbuff_t *tvb, int offset, packet_info *pinfo, proto_tree *xdlc_tree, int hf_xdlc_control, int ett_xdlc_control, const xdlc_cf_items *cf_items_nonext, const xdlc_cf_items *cf_items_ext, const value_string *u_modifier_short_vals_cmd, const value_string *u_modifier_short_vals_resp, bool is_response, bool is_extended, bool append_info) { uint16_t control; int control_len; const xdlc_cf_items *cf_items; const char *control_format; uint16_t poll_final; char *info; proto_tree *tc, *control_tree; const char *frame_type = NULL; const char *modifier; info=(char *)wmem_alloc(pinfo->pool, 80); switch (tvb_get_uint8(tvb, offset) & 0x03) { case XDLC_S: /* * Supervisory frame. */ if (is_extended) { control = tvb_get_letohs(tvb, offset); control_len = 2; cf_items = cf_items_ext; control_format = "Control field: %s (0x%04X)"; } else { control = tvb_get_uint8(tvb, offset); control_len = 1; cf_items = cf_items_nonext; control_format = "Control field: %s (0x%02X)"; } switch (control & XDLC_S_FTYPE_MASK) { case XDLC_RR: frame_type = "RR"; break; case XDLC_RNR: frame_type = "RNR"; break; case XDLC_REJ: frame_type = "REJ"; break; case XDLC_SREJ: frame_type = "SREJ"; break; } if (is_extended) { poll_final = (control & XDLC_P_F_EXT); snprintf(info, 80, "S%s, func=%s, N(R)=%u", (poll_final ? (is_response ? " F" : " P") : ""), frame_type, (control & XDLC_N_R_EXT_MASK) >> XDLC_N_R_EXT_SHIFT); } else { poll_final = (control & XDLC_P_F); snprintf(info, 80, "S%s, func=%s, N(R)=%u", (poll_final ? (is_response ? " F" : " P") : ""), frame_type, (control & XDLC_N_R_MASK) >> XDLC_N_R_SHIFT); } if (append_info) { col_append_str(pinfo->cinfo, COL_INFO, ", "); col_append_str(pinfo->cinfo, COL_INFO, info); } else { col_add_str(pinfo->cinfo, COL_INFO, info); } if (xdlc_tree) { tc = proto_tree_add_uint_format(xdlc_tree, hf_xdlc_control, tvb, offset, control_len, control, control_format, info, control); control_tree = proto_item_add_subtree(tc, ett_xdlc_control); proto_tree_add_uint(control_tree, *cf_items->hf_xdlc_n_r, tvb, offset, control_len, control); if (poll_final) { proto_tree_add_boolean(control_tree, (is_response ? *cf_items->hf_xdlc_f : *cf_items->hf_xdlc_p), tvb, offset, control_len, control); } proto_tree_add_uint(control_tree, *cf_items->hf_xdlc_s_ftype, tvb, offset, control_len, control); /* This will always say it's a supervisory frame */ proto_tree_add_uint(control_tree, *cf_items->hf_xdlc_ftype_s_u, tvb, offset, control_len, control); } break; case XDLC_U: /* * Unnumbered frame. * * XXX - is this two octets, with a P/F bit, in HDLC extended * operation? It's one octet in LLC, even though the control * field of I and S frames is a 2-byte extended-operation field * in LLC. Given that there are no sequence numbers in the * control field of a U frame, there doesn't appear to be any * need for it to be 2 bytes in extended operation. */ if (u_modifier_short_vals_cmd == NULL) u_modifier_short_vals_cmd = modifier_short_vals_cmd; if (u_modifier_short_vals_resp == NULL) u_modifier_short_vals_resp = modifier_short_vals_resp; control = tvb_get_uint8(tvb, offset); control_len = 1; cf_items = cf_items_nonext; control_format = "Control field: %s (0x%02X)"; if (is_response) { modifier = val_to_str(control & XDLC_U_MODIFIER_MASK, u_modifier_short_vals_resp, "Unknown"); } else { modifier = val_to_str(control & XDLC_U_MODIFIER_MASK, u_modifier_short_vals_cmd, "Unknown"); } poll_final = (control & XDLC_P_F); snprintf(info, 80, "U%s, func=%s", (poll_final ? (is_response ? " F" : " P") : ""), modifier); if (append_info) { col_append_str(pinfo->cinfo, COL_INFO, ", "); col_append_str(pinfo->cinfo, COL_INFO, info); } else { col_add_str(pinfo->cinfo, COL_INFO, info); } if (xdlc_tree) { tc = proto_tree_add_uint_format(xdlc_tree, hf_xdlc_control, tvb, offset, control_len, control, control_format, info, control); control_tree = proto_item_add_subtree(tc, ett_xdlc_control); if (poll_final) { proto_tree_add_boolean(control_tree, (is_response ? *cf_items->hf_xdlc_f: *cf_items->hf_xdlc_p), tvb, offset, control_len, control); } proto_tree_add_uint(control_tree, (is_response ? *cf_items->hf_xdlc_u_modifier_resp : *cf_items->hf_xdlc_u_modifier_cmd), tvb, offset, control_len, control); /* This will always say it's an unnumbered frame */ proto_tree_add_uint(control_tree, *cf_items->hf_xdlc_ftype_s_u, tvb, offset, control_len, control); } break; default: /* * Information frame. */ if (is_extended) { control = tvb_get_letohs(tvb, offset); control_len = 2; cf_items = cf_items_ext; control_format = "Control field: %s (0x%04X)"; poll_final = (control & XDLC_P_F_EXT); snprintf(info, 80, "I%s, N(R)=%u, N(S)=%u", ((control & XDLC_P_F_EXT) ? " P" : ""), (control & XDLC_N_R_EXT_MASK) >> XDLC_N_R_EXT_SHIFT, (control & XDLC_N_S_EXT_MASK) >> XDLC_N_S_EXT_SHIFT); } else { control = tvb_get_uint8(tvb, offset); control_len = 1; cf_items = cf_items_nonext; control_format = "Control field: %s (0x%02X)"; poll_final = (control & XDLC_P_F); snprintf(info, 80, "I%s, N(R)=%u, N(S)=%u", ((control & XDLC_P_F) ? " P" : ""), (control & XDLC_N_R_MASK) >> XDLC_N_R_SHIFT, (control & XDLC_N_S_MASK) >> XDLC_N_S_SHIFT); } if (append_info) { col_append_str(pinfo->cinfo, COL_INFO, ", "); col_append_str(pinfo->cinfo, COL_INFO, info); } else { col_add_str(pinfo->cinfo, COL_INFO, info); } if (xdlc_tree) { tc = proto_tree_add_uint_format(xdlc_tree, hf_xdlc_control, tvb, offset, control_len, control, control_format, info, control); control_tree = proto_item_add_subtree(tc, ett_xdlc_control); proto_tree_add_uint(control_tree, *cf_items->hf_xdlc_n_r, tvb, offset, control_len, control); proto_tree_add_uint(control_tree, *cf_items->hf_xdlc_n_s, tvb, offset, control_len, control); if (poll_final) { proto_tree_add_boolean(control_tree, *cf_items->hf_xdlc_p, tvb, offset, control_len, control); } /* This will always say it's an information frame */ proto_tree_add_uint(control_tree, *cf_items->hf_xdlc_ftype_i, tvb, offset, control_len, control); } break; } return control; } /* * 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: */