/* $NetBSD: print-gre.c,v 1.3 2004/09/27 23:04:24 dyoung Exp $ */ /* $OpenBSD: print-gre.c,v 1.6 2002/10/30 03:04:04 fgsch Exp $ */ /* * Copyright (c) 2002 Jason L. Wright (jason@thought.net) * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by Jason L. Wright * 4. The name of the author may not be used to endorse or promote products * derived from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. */ /* * tcpdump filter for GRE - Generic Routing Encapsulation * RFC1701 (GRE), RFC1702 (GRE IPv4), and RFC2637 (Enhanced GRE) */ #include #ifndef lint #if 0 static const char rcsid[] _U_ = "@(#) Header: /tcpdump/master/tcpdump/print-gre.c,v 1.22.2.2 2003/11/16 08:51:24 guy Exp (LBL)"; #else __RCSID("$NetBSD: print-gre.c,v 1.3 2004/09/27 23:04:24 dyoung Exp $"); #endif #endif #ifdef HAVE_CONFIG_H #include "config.h" #endif #include #include #include #include "interface.h" #include "addrtoname.h" #include "extract.h" #include "ip.h" #define GRE_CP 0x8000 /* checksum present */ #define GRE_RP 0x4000 /* routing present */ #define GRE_KP 0x2000 /* key present */ #define GRE_SP 0x1000 /* sequence# present */ #define GRE_sP 0x0800 /* source routing */ #define GRE_RECRS 0x0700 /* recursion count */ #define GRE_AP 0x0080 /* acknowledgment# present */ #define GRE_VERS 0x0007 /* protocol version */ #define GREPROTO_IP 0x0800 /* IP */ #define GREPROTO_PPP 0x880b /* PPTP */ #define GREPROTO_ISO 0x00fe /* OSI */ /* source route entry types */ #define GRESRE_IP 0x0800 /* IP */ #define GRESRE_ASN 0xfffe /* ASN */ void gre_print_0(const u_char *, u_int); void gre_print_1(const u_char *, u_int); void gre_sre_print(u_int16_t, u_int8_t, u_int8_t, const u_char *, u_int); void gre_sre_ip_print(u_int8_t, u_int8_t, const u_char *, u_int); void gre_sre_asn_print(u_int8_t, u_int8_t, const u_char *, u_int); void gre_print(const u_char *bp, u_int length) { u_int len = length, vers; if (len < 2) { printf("[|gre]"); return; } vers = EXTRACT_16BITS(bp) & 7; if (vers == 0) gre_print_0(bp, len); else if (vers == 1) gre_print_1(bp, len); else printf("gre-unknown-version=%u", vers); return; } void gre_print_0(const u_char *bp, u_int length) { u_int len = length; u_int16_t flags, prot; flags = EXTRACT_16BITS(bp); if (vflag) { printf("[%s%s%s%s%s] ", (flags & GRE_CP) ? "C" : "", (flags & GRE_RP) ? "R" : "", (flags & GRE_KP) ? "K" : "", (flags & GRE_SP) ? "S" : "", (flags & GRE_sP) ? "s" : ""); } len -= 2; bp += 2; if (len < 2) goto trunc; prot = EXTRACT_16BITS(bp); len -= 2; bp += 2; if ((flags & GRE_CP) | (flags & GRE_RP)) { if (len < 2) goto trunc; if (vflag) printf("sum 0x%x ", EXTRACT_16BITS(bp)); bp += 2; len -= 2; if (len < 2) goto trunc; printf("off 0x%x ", EXTRACT_16BITS(bp)); bp += 2; len -= 2; } if (flags & GRE_KP) { if (len < 4) goto trunc; printf("key=0x%x ", EXTRACT_32BITS(bp)); bp += 4; len -= 4; } if (flags & GRE_SP) { if (len < 4) goto trunc; printf("seq %u ", EXTRACT_32BITS(bp)); bp += 4; len -= 4; } if (flags & GRE_RP) { for (;;) { u_int16_t af; u_int8_t sreoff; u_int8_t srelen; if (len < 4) goto trunc; af = EXTRACT_16BITS(bp); sreoff = *(bp + 2); srelen = *(bp + 3); bp += 4; len -= 4; if (af == 0 && srelen == 0) break; gre_sre_print(af, sreoff, srelen, bp, len); if (len < srelen) goto trunc; bp += srelen; len -= srelen; } } switch (prot) { case GREPROTO_IP: ip_print(bp, len); break; case GREPROTO_ISO: isoclns_print(bp, len, len); break; default: printf("gre-proto-0x%x", prot); } return; trunc: printf("[|gre]"); } void gre_print_1(const u_char *bp, u_int length) { u_int len = length; u_int16_t flags, prot; flags = EXTRACT_16BITS(bp); len -= 2; bp += 2; if (vflag) { printf("[%s%s%s%s%s%s] ", (flags & GRE_CP) ? "C" : "", (flags & GRE_RP) ? "R" : "", (flags & GRE_KP) ? "K" : "", (flags & GRE_SP) ? "S" : "", (flags & GRE_sP) ? "s" : "", (flags & GRE_AP) ? "A" : ""); } if (len < 2) goto trunc; prot = EXTRACT_16BITS(bp); len -= 2; bp += 2; if (flags & GRE_CP) { printf("cpset!"); return; } if (flags & GRE_RP) { printf("rpset!"); return; } if ((flags & GRE_KP) == 0) { printf("kpunset!"); return; } if (flags & GRE_sP) { printf("spset!"); return; } if (flags & GRE_KP) { u_int32_t k; if (len < 4) goto trunc; k = EXTRACT_32BITS(bp); printf("call %d ", k & 0xffff); len -= 4; bp += 4; } if (flags & GRE_SP) { if (len < 4) goto trunc; printf("seq %u ", EXTRACT_32BITS(bp)); bp += 4; len -= 4; } if (flags & GRE_AP) { if (len < 4) goto trunc; printf("ack %u ", EXTRACT_32BITS(bp)); bp += 4; len -= 4; } if ((flags & GRE_SP) == 0) { printf("no-payload"); return; } switch (prot) { case GREPROTO_PPP: printf("gre-ppp-payload"); break; default: printf("gre-proto-0x%x", prot); break; } return; trunc: printf("[|gre]"); } void gre_sre_print(u_int16_t af, u_int8_t sreoff, u_int8_t srelen, const u_char *bp, u_int len) { switch (af) { case GRESRE_IP: printf("(rtaf=ip"); gre_sre_ip_print(sreoff, srelen, bp, len); printf(") "); break; case GRESRE_ASN: printf("(rtaf=asn"); gre_sre_asn_print(sreoff, srelen, bp, len); printf(") "); break; default: printf("(rtaf=0x%x) ", af); } } void gre_sre_ip_print(u_int8_t sreoff, u_int8_t srelen, const u_char *bp, u_int len) { struct in_addr a; const u_char *up = bp; if (sreoff & 3) { printf(" badoffset=%u", sreoff); return; } if (srelen & 3) { printf(" badlength=%u", srelen); return; } if (sreoff >= srelen) { printf(" badoff/len=%u/%u", sreoff, srelen); return; } for (;;) { if (len < 4 || srelen == 0) return; memcpy(&a, bp, sizeof(a)); printf(" %s%s", ((bp - up) == sreoff) ? "*" : "", inet_ntoa(a)); bp += 4; len -= 4; srelen -= 4; } } void gre_sre_asn_print(u_int8_t sreoff, u_int8_t srelen, const u_char *bp, u_int len) { const u_char *up = bp; if (sreoff & 1) { printf(" badoffset=%u", sreoff); return; } if (srelen & 1) { printf(" badlength=%u", srelen); return; } if (sreoff >= srelen) { printf(" badoff/len=%u/%u", sreoff, srelen); return; } for (;;) { if (len < 2 || srelen == 0) return; printf(" %s%x", ((bp - up) == sreoff) ? "*" : "", EXTRACT_16BITS(bp)); bp += 2; len -= 2; srelen -= 2; } }