/* packet-gre.c * Routines for the Generic Routing Encapsulation (GRE) protocol * Brad Robel-Forrest * * $Id: packet-gre.c,v 1.4 1999/07/29 05:46:55 gram 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. */ #ifdef HAVE_CONFIG_H # include "config.h" #endif #ifdef HAVE_SYS_TYPES_H # include #endif #ifdef HAVE_NETINET_IN_H #include #endif #include #include "packet.h" static int proto_gre = -1; /* bit positions for flags in header */ #define GH_B_C 0x8000 #define GH_B_R 0x4000 #define GH_B_K 0x2000 #define GH_B_S 0x1000 #define GH_B_s 0x0800 #define GH_B_RECUR 0x0700 #define GH_P_A 0x0080 /* only in special PPTPized GRE header */ #define GH_P_FLAGS 0x0078 /* only in special PPTPized GRE header */ #define GH_R_FLAGS 0x00F8 #define GH_B_VER 0x0007 #define GRE_PPP 0x880B static int calc_len(guint16, int); static void add_flags_and_ver(proto_tree *, guint16, int, int); void dissect_gre(const u_char *pd, int offset, frame_data *fd, proto_tree *tree) { guint16 flags_and_ver = pntohs(pd + offset); guint16 type = pntohs(pd + offset + sizeof(flags_and_ver)); static const value_string typevals[] = { { GRE_PPP, "PPP" }, { 0, NULL } }; if (check_col(fd, COL_PROTOCOL)) col_add_str(fd, COL_PROTOCOL, "GRE"); if (check_col(fd, COL_INFO)) { if (type == GRE_PPP) col_add_str(fd, COL_INFO, "Encapsulated PPP"); else col_add_str(fd, COL_INFO, "Encapsulated unknown"); } if (fd->cap_len > offset && tree) { int is_ppp; proto_item * ti; proto_tree * gre_tree; if (type == GRE_PPP) { is_ppp = 1; ti = proto_tree_add_item_format(tree, proto_gre, offset, calc_len(flags_and_ver, 1), NULL, "Generic Routing Encapsulation (PPP)"); gre_tree = proto_item_add_subtree(ti, ETT_GRE); add_flags_and_ver(gre_tree, flags_and_ver, offset, 1); } else { is_ppp = 0; ti = proto_tree_add_item(tree, proto_gre, offset, calc_len(flags_and_ver, 1), NULL); gre_tree = proto_item_add_subtree(ti, ETT_GRE); add_flags_and_ver(gre_tree, flags_and_ver, offset, 0); } offset += sizeof(flags_and_ver); proto_tree_add_text(gre_tree, offset, sizeof(type), "Protocol Type: %s (%#04x)", val_to_str(type, typevals, "Unknown"), type); offset += sizeof(type); if (flags_and_ver & GH_B_C || flags_and_ver & GH_B_R) { guint16 checksum = pntohs(pd + offset); proto_tree_add_text(gre_tree, offset, sizeof(checksum), "Checksum: %u", checksum); offset += sizeof(checksum); } if (flags_and_ver & GH_B_C || flags_and_ver & GH_B_R) { guint16 rtoffset = pntohs(pd + offset); proto_tree_add_text(gre_tree, offset, sizeof(rtoffset), "Offset: %u", rtoffset); offset += sizeof(rtoffset); } if (flags_and_ver & GH_B_K) { if (is_ppp) { guint16 paylen; guint16 callid; paylen = pntohs(pd + offset); proto_tree_add_text(gre_tree, offset, sizeof(paylen), "Payload length: %u", paylen); offset += sizeof(paylen); callid = pntohs(pd + offset); proto_tree_add_text(gre_tree, offset, sizeof(callid), "Call ID: %u", callid); offset += sizeof(callid); } else { guint32 key = pntohl(pd + offset); proto_tree_add_text(gre_tree, offset, sizeof(key), "Key: %u", key); offset += sizeof(key); } } if (flags_and_ver & GH_B_S) { guint32 seqnum = pntohl(pd + offset); proto_tree_add_text(gre_tree, offset, sizeof(seqnum), "Sequence number: %u", seqnum); offset += sizeof(seqnum); } if (is_ppp && flags_and_ver & GH_P_A) { guint32 acknum = pntohl(pd + offset); proto_tree_add_text(gre_tree, offset, sizeof(acknum), "Acknowledgement number: %u", acknum); offset += sizeof(acknum); } if (flags_and_ver & GH_B_R) { proto_tree_add_text(gre_tree, offset, sizeof(guint16), "Address family: %u", pntohs(pd + offset)); offset += sizeof(guint16); proto_tree_add_text(gre_tree, offset, 1, "SRE offset: %u", pd[offset++]); proto_tree_add_text(gre_tree, offset, 1, "SRE length: %u", pd[offset++]); } switch (type) { case GRE_PPP: dissect_payload_ppp(pd, offset, fd, tree); break; default: dissect_data(pd, offset, fd, gre_tree); } } } static int calc_len(guint16 flags_and_ver, int is_ppp) { int len = 4; if (flags_and_ver & GH_B_C || flags_and_ver & GH_B_R) len += 4; if (flags_and_ver & GH_B_K) len += 4; if (flags_and_ver & GH_B_S) len += 4; if (is_ppp && flags_and_ver & GH_P_A) len += 4; return len; } static void add_flags_and_ver(proto_tree *tree, guint16 flags_and_ver, int offset, int is_ppp) { proto_item * ti; proto_tree * fv_tree; int nbits = sizeof(flags_and_ver) * 8; ti = proto_tree_add_text(tree, offset, 2, "Flags and version: %#08x", flags_and_ver); fv_tree = proto_item_add_subtree(ti, ETT_GRE_FLAGS); proto_tree_add_text(fv_tree, offset, sizeof(flags_and_ver), "%s", decode_boolean_bitfield(flags_and_ver, GH_B_C, nbits, "Checksum", "No checksum")); proto_tree_add_text(fv_tree, offset, sizeof(flags_and_ver), "%s", decode_boolean_bitfield(flags_and_ver, GH_B_R, nbits, "Routing", "No routing")); proto_tree_add_text(fv_tree, offset, sizeof(flags_and_ver), "%s", decode_boolean_bitfield(flags_and_ver, GH_B_K, nbits, "Key", "No key")); proto_tree_add_text(fv_tree, offset, sizeof(flags_and_ver), "%s", decode_boolean_bitfield(flags_and_ver, GH_B_S, nbits, "Sequence number", "No sequence number")); proto_tree_add_text(fv_tree, offset, sizeof(flags_and_ver), "%s", decode_boolean_bitfield(flags_and_ver, GH_B_s, nbits, "Strict source route", "No strict source route")); proto_tree_add_text(fv_tree, offset, sizeof(flags_and_ver), "%s", decode_numeric_bitfield(flags_and_ver, GH_B_RECUR, nbits, "Recursion control: %u")); if (is_ppp) { proto_tree_add_text(fv_tree, offset, sizeof(flags_and_ver), "%s", decode_boolean_bitfield(flags_and_ver, GH_P_A, nbits, "Acknowledgment number", "No acknowledgment number")); proto_tree_add_text(fv_tree, offset, sizeof(flags_and_ver), "%s", decode_numeric_bitfield(flags_and_ver, GH_P_FLAGS, nbits, "Flags: %u")); } else { proto_tree_add_text(fv_tree, offset, sizeof(flags_and_ver), "%s", decode_numeric_bitfield(flags_and_ver, GH_R_FLAGS, nbits, "Flags: %u")); } proto_tree_add_text(fv_tree, offset, sizeof(flags_and_ver), "%s", decode_numeric_bitfield(flags_and_ver, GH_B_VER, nbits, "Version: %u")); } void proto_register_gre(void) { /* static hf_register_info hf[] = { { &variable, { "Name", "gre.abbreviation", TYPE, VALS_POINTER }}, };*/ proto_gre = proto_register_protocol("Generic Routing Encapsulation", "gre"); /* proto_register_field_array(proto_gre, hf, array_length(hf));*/ }