/* packet-fr.c * Routines for Frame Relay dissection * * Copyright 2001, Paul Ionescu * * $Id: packet-fr.c,v 1.18 2001/06/18 02:17:46 guy Exp $ * * Ethereal - Network traffic analyzer * By Gerald Combs * Copyright 1998 Gerald Combs * * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version 2 * of the License, or (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. * * * References: * * http://www.protocols.com/pbook/frame.htm * http://www.frforum.com/5000/Approved/FRF.3/FRF.3.2.pdf * ITU Recommendation Q.933 * RFC-1490 * RFC-2427 * Cisco encapsulation * http://www.trillium.com/whats-new/wp_frmrly.html * */ #ifdef HAVE_CONFIG_H # include "config.h" #endif #include #include #include #include #include #include "packet.h" #include "packet-fr.h" #include "packet-osi.h" #include "packet-llc.h" #include "packet-chdlc.h" #include "xdlc.h" #include "etypes.h" #include "oui.h" #include "nlpid.h" #include "greproto.h" #include "conversation.h" /* * Bits in the address field. */ #define FRELAY_DLCI 0xfcf0 /* 2 byte DLCI Address */ #define FRELAY_CR 0x0200 /* Command/Response bit */ #define FRELAY_EA 0x0001 /* Address Extension bit */ #define FRELAY_FECN 0x0008 /* Forward Explicit Congestion Notification */ #define FRELAY_BECN 0x0004 /* Backward Explicit Congestion Notification */ #define FRELAY_DE 0x0002 /* Discard Eligibility */ #define FRELAY_DC 0x0002 /* Control bits */ /* * Extract the DLCI from the address field. */ #define EXTRACT_DLCI(addr) ((((addr)&0xfc00) >> 6) | (((addr)&0xf0) >> 4)) #define FROM_DCE 0x80 /* for direction setting */ static gint proto_fr = -1; static gint ett_fr = -1; static gint hf_fr_dlci = -1; static gint hf_fr_cr = -1; static gint hf_fr_becn = -1; static gint hf_fr_fecn = -1; static gint hf_fr_de = -1; static gint hf_fr_ea = -1; static gint hf_fr_dc = -1; static gint hf_fr_nlpid = -1; static gint hf_fr_oui = -1; static gint hf_fr_pid = -1; static gint hf_fr_snaptype = -1; static gint hf_fr_chdlctype = -1; static const true_false_string cmd_string = { "Command", "Response" }; static const true_false_string ctrl_string = { "DLCI Address", "Control" }; static const true_false_string ea_string = { "Last Octet", "More Follows" }; /* * This isn't the same as "nlpid_vals[]"; 0x08 is Q.933, not Q.931, * and 0x09 is LMI, not Q.2931. */ static const value_string fr_nlpid_vals[] = { { NLPID_NULL, "NULL" }, { NLPID_T_70, "T.70" }, { NLPID_X_633, "X.633" }, { NLPID_Q_931, "Q.933" }, { NLPID_LMI, "LMI" }, { NLPID_Q_2119, "Q.2119" }, { NLPID_SNAP, "SNAP" }, { NLPID_ISO8473_CLNP, "CLNP" }, { NLPID_ISO9542_ESIS, "ESIS" }, { NLPID_ISO10589_ISIS, "ISIS" }, { NLPID_ISO10747_IDRP, "IDRP" }, { NLPID_ISO9542X25_ESIS, "ESIS (X.25)" }, { NLPID_ISO10030, "ISO 10030" }, { NLPID_ISO11577, "ISO 11577" }, { NLPID_COMPRESSED, "Data compression protocol" }, { NLPID_IP, "IP" }, { NLPID_PPP, "PPP" }, { 0, NULL }, }; dissector_table_t fr_subdissector_table; static void dissect_fr_nlpid(tvbuff_t *tvb, int offset, packet_info *pinfo, proto_tree *tree, proto_item *ti, proto_tree *fr_tree, guint8 fr_ctrl); static void dissect_lapf(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree); static void dissect_fr_xid(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree); static void dissect_fr(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree) { proto_item *ti = NULL; proto_tree *fr_tree = NULL; guint16 fr_header,fr_type,offset=2; /* default header length of FR is 2 bytes */ guint16 address; char buf[32]; guint8 fr_ctrl; pinfo->current_proto = "Frame Relay"; if (check_col(pinfo->fd, COL_PROTOCOL)) col_set_str(pinfo->fd, COL_PROTOCOL, "FR"); if (pinfo->pseudo_header->x25.flags & FROM_DCE) { if(check_col(pinfo->fd, COL_RES_DL_DST)) col_set_str(pinfo->fd, COL_RES_DL_DST, "DTE"); if(check_col(pinfo->fd, COL_RES_DL_SRC)) col_set_str(pinfo->fd, COL_RES_DL_SRC, "DCE"); } else { if(check_col(pinfo->fd, COL_RES_DL_DST)) col_set_str(pinfo->fd, COL_RES_DL_DST, "DCE"); if(check_col(pinfo->fd, COL_RES_DL_SRC)) col_set_str(pinfo->fd, COL_RES_DL_SRC, "DTE"); } /*XXX We should check the EA bits and use that to generate the address. */ fr_header = tvb_get_ntohs(tvb, 0); fr_ctrl = tvb_get_guint8( tvb, 2); address = EXTRACT_DLCI(fr_header); if (check_col(pinfo->fd, COL_INFO)) col_add_fstr(pinfo->fd, COL_INFO, "DLCI %u", address); if (tree) { ti = proto_tree_add_protocol_format(tree, proto_fr, tvb, 0, 3, "Frame Relay"); fr_tree = proto_item_add_subtree(ti, ett_fr); decode_bitfield_value(buf, fr_header, FRELAY_DLCI, 16); proto_tree_add_uint_format(fr_tree, hf_fr_dlci, tvb, 0, 2, address, "%sDLCI: %u", buf, address); proto_tree_add_boolean(fr_tree, hf_fr_cr, tvb, 0, offset, fr_header); proto_tree_add_boolean(fr_tree, hf_fr_fecn, tvb, 0, offset, fr_header); proto_tree_add_boolean(fr_tree, hf_fr_becn, tvb, 0, offset, fr_header); proto_tree_add_boolean(fr_tree, hf_fr_de, tvb, 0, offset, fr_header); proto_tree_add_boolean(fr_tree, hf_fr_ea, tvb, 0, offset, fr_header); } if (fr_ctrl == XDLC_U) { if (tree) { proto_tree_add_text(fr_tree, tvb, offset, 0, "------- Q.933 Encapsulation -------"); /* * XXX - if we're going to show this as Unnumbered * Information, should we just hand it to * "dissect_xdlc_control()"? */ proto_tree_add_text(fr_tree, tvb, offset, 1, "Unnumbered Information"); } offset++; SET_ADDRESS(&pinfo->dl_src, AT_DLCI, 2, (guint8*)&address); dissect_fr_nlpid(tvb, offset, pinfo, tree, ti, fr_tree, fr_ctrl); } else { if (address == 0) { /* this must be some sort of lapf on DLCI 0 for SVC */ /* because DLCI 0 is rezerved for LMI and SVC signaling encaplulated in lapf */ /* and LMI is transmitted in unnumbered information (03) */ /* so this must be lapf (guessing) */ dissect_lapf(tvb_new_subset(tvb,offset,-1,-1),pinfo,tree); return; } if (fr_ctrl == (XDLC_U|XDLC_XID)) { dissect_fr_xid(tvb_new_subset(tvb,offset,-1,-1),pinfo,tree); return; } /* * If the data does not start with unnumbered information (03) and * the DLCI# is not 0, then there may be Cisco Frame Relay encapsulation. */ proto_tree_add_text(fr_tree, tvb, offset, 0, "------- Cisco Encapsulation -------"); fr_type = tvb_get_ntohs(tvb, offset); if (ti != NULL) { /* Include the Cisco HDLC type in the top-level protocol tree item. */ proto_item_set_len(ti, offset+2); } chdlctype(fr_type, tvb, offset+2, pinfo, tree, fr_tree, hf_fr_chdlctype); } } void dissect_fr_uncompressed(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree) { proto_item *ti = NULL; proto_tree *fr_tree = NULL; CHECK_DISPLAY_AS_DATA(proto_fr, tvb, pinfo, tree); pinfo->current_proto = "Frame Relay"; if (check_col(pinfo->fd, COL_PROTOCOL)) col_set_str(pinfo->fd, COL_PROTOCOL, "FR"); if (check_col(pinfo->fd, COL_INFO)) col_clear(pinfo->fd, COL_INFO); if (tree) { ti = proto_tree_add_protocol_format(tree, proto_fr, tvb, 0, 4, "Frame Relay"); fr_tree = proto_item_add_subtree(ti, ett_fr); } dissect_fr_nlpid(tvb, 0, pinfo, tree, ti, fr_tree, XDLC_U); } static void dissect_fr_nlpid(tvbuff_t *tvb, int offset, packet_info *pinfo, proto_tree *tree, proto_item *ti, proto_tree *fr_tree, guint8 fr_ctrl) { guint8 fr_nlpid; tvbuff_t *next_tvb; fr_nlpid = tvb_get_guint8 (tvb,offset); if (fr_nlpid == 0) { if (tree) proto_tree_add_text(fr_tree, tvb, offset, 1, "Padding"); offset++; if (ti != NULL) { /* Include the padding in the top-level protocol tree item. */ proto_item_set_len(ti, offset); } fr_nlpid=tvb_get_guint8( tvb,offset); } /* * OSI network layer protocols consider the NLPID to be part * of the frame, so we'll pass it as part of the payload and, * if the protocol is one of those, add it as a hidden item here. */ next_tvb = tvb_new_subset(tvb,offset,-1,-1); if (dissector_try_port(osinl_subdissector_table, fr_nlpid, next_tvb, pinfo, tree)) { /* * Yes, we got a match. Add the NLPID as a hidden item, * so you can, at least, filter on it. */ if (tree) proto_tree_add_uint_hidden(fr_tree, hf_fr_nlpid, tvb, offset, 1, fr_nlpid ); return; } /* * All other protocols don't. * * XXX - not true for Q.933 and LMI, but we don't yet have a * Q.933 dissector (it'd be similar to the Q.931 dissector, * but I don't think it'd be identical, although it's less * different than is the Q.2931 dissector), and the LMI * dissector doesn't yet put the protocol discriminator * (NLPID) into the tree. * * Note that an NLPID of 0x08 for Q.933 could either be a * Q.933 signaling message or a message for a protocol * identified by a 2-octet layer 2 protocol type and a * 2-octet layer 3 protocol type, those protocol type * octets having the values from octets 6, 6a, 7, and 7a * of a Q.931 low layer compatibility information element * (section 4.5.19 of Q.931; Q.933 says they have the values * from a Q.933 low layer compatibility information element, * but Q.933 low layer compatibility information elements * don't have protocol values in them). * * Assuming that, as Q.933 seems to imply, that Q.933 messages * look just like Q.931 messages except where it explicitly * says they differ, then the octet after the NLPID would, * in a Q.933 message, have its upper 4 bits zero (that's * the length of the call reference value, in Q.931, and * is limited to 15 or fewer octets). As appears to be the case, * octet 6 of a Q.931 low layer compatibility element has the * 0x40 bit set, so you can distinguish between a Q.933 * message and an encapsulated packet by checking whether * the upper 4 bits of the octet after the NLPID are zero. * * To handle this, we'd handle Q.933's NLPID specially, which * we'd want to do anyway, so that we give it a tvbuff that * includes the NLPID. */ if (tree) proto_tree_add_uint(fr_tree, hf_fr_nlpid, tvb, offset, 1, fr_nlpid ); offset++; switch (fr_nlpid) { case NLPID_SNAP: if (ti != NULL) { /* Include the NLPID and SNAP header in the top-level protocol tree item. */ proto_item_set_len(ti, offset+5); } dissect_snap(tvb, offset, pinfo, tree, fr_tree, fr_ctrl, hf_fr_oui, hf_fr_snaptype, hf_fr_pid, 0); return; default: if (ti != NULL) { /* Include the NLPID in the top-level protocol tree item. */ proto_item_set_len(ti, offset); } next_tvb = tvb_new_subset(tvb,offset,-1,-1); if (!dissector_try_port(fr_subdissector_table,fr_nlpid, next_tvb, pinfo, tree)) dissect_data(next_tvb, 0, pinfo, tree); break; } } static void dissect_lapf(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree) { proto_tree_add_text(tree, tvb, 0, 0, "Frame relay lapf not yet implemented"); dissect_data(tvb_new_subset(tvb,0,-1,-1),0,pinfo,tree); } static void dissect_fr_xid(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree) { proto_tree_add_text(tree, tvb, 0, 0, "Frame relay xid not yet implemented"); dissect_data(tvb_new_subset(tvb,0,-1,-1),0,pinfo,tree); } /* Register the protocol with Ethereal */ void proto_register_fr(void) { static hf_register_info hf[] = { { &hf_fr_dlci, { "DLCI", "fr.dlci", FT_UINT16, BASE_DEC, NULL, FRELAY_DLCI, "Data-Link Connection Identifier", HFILL }}, { &hf_fr_cr, { "CR", "fr.cr", FT_BOOLEAN, 16, TFS(&cmd_string), FRELAY_CR, "Command/Response", HFILL }}, { &hf_fr_dc, { "DC", "fr.dc", FT_BOOLEAN, 16, TFS(&ctrl_string), FRELAY_CR, "Address/Control", HFILL }}, { &hf_fr_fecn, { "FECN", "fr.fecn", FT_BOOLEAN, 16, NULL, FRELAY_FECN, "Forward Explicit Congestion Notification", HFILL }}, { &hf_fr_becn, { "BECN", "fr.becn", FT_BOOLEAN, 16, NULL, FRELAY_BECN, "Backward Explicit Congestion Notification", HFILL }}, { &hf_fr_de, { "DE", "fr.de", FT_BOOLEAN, 16, NULL, FRELAY_DE, "Discard Eligibility", HFILL }}, { &hf_fr_ea, { "EA", "fr.ea", FT_BOOLEAN, 16, TFS(&ea_string), FRELAY_EA, "Extended Address", HFILL }}, { &hf_fr_nlpid, { "NLPID", "fr.nlpid", FT_UINT8, BASE_HEX, VALS(fr_nlpid_vals), 0x0, "FrameRelay Encapsulated Protocol NLPID", HFILL }}, { &hf_fr_oui, { "Organization Code", "fr.snap.oui", FT_UINT24, BASE_HEX, VALS(oui_vals), 0x0, "", HFILL }}, { &hf_fr_pid, { "Protocol ID", "fr.snap.pid", FT_UINT16, BASE_HEX, NULL, 0x0, "", HFILL }}, { &hf_fr_snaptype, { "Type", "fr.snaptype", FT_UINT16, BASE_HEX, VALS(etype_vals), 0x0, "FrameRelay SNAP Encapsulated Protocol", HFILL }}, { &hf_fr_chdlctype, { "Type", "fr.chdlctype", FT_UINT16, BASE_HEX, VALS(chdlc_vals), 0x0, "FrameRelay Cisco HDLC Encapsulated Protocol", HFILL }}, }; /* Setup protocol subtree array */ static gint *ett[] = { &ett_fr, }; proto_fr = proto_register_protocol("Frame Relay", "FR", "fr"); proto_register_field_array(proto_fr, hf, array_length(hf)); proto_register_subtree_array(ett, array_length(ett)); fr_subdissector_table = register_dissector_table("fr.ietf"); } void proto_reg_handoff_fr(void) { dissector_add("wtap_encap", WTAP_ENCAP_FRELAY, dissect_fr, proto_fr); dissector_add("gre.proto", GRE_FR, dissect_fr, proto_fr); }