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-rw-r--r--print-gre.c414
1 files changed, 414 insertions, 0 deletions
diff --git a/print-gre.c b/print-gre.c
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+/* $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.
+ *
+ * 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.
+ */
+
+/* \summary: Generic Routing Encapsulation (GRE) printer */
+
+/*
+ * netdissect printer for GRE - Generic Routing Encapsulation
+ * RFC1701 (GRE), RFC1702 (GRE IPv4), and RFC2637 (Enhanced GRE)
+ */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include "netdissect-stdinc.h"
+
+#include "netdissect.h"
+#include "addrtostr.h"
+#include "extract.h"
+#include "ethertype.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_AP 0x0080 /* acknowledgment# present */
+
+static const struct tok gre_flag_values[] = {
+ { GRE_CP, "checksum present"},
+ { GRE_RP, "routing present"},
+ { GRE_KP, "key present"},
+ { GRE_SP, "sequence# present"},
+ { GRE_sP, "source routing present"},
+ { GRE_AP, "ack present"},
+ { 0, NULL }
+};
+
+#define GRE_RECRS_MASK 0x0700 /* recursion count */
+#define GRE_VERS_MASK 0x0007 /* protocol version */
+
+/* source route entry types */
+#define GRESRE_IP 0x0800 /* IP */
+#define GRESRE_ASN 0xfffe /* ASN */
+
+static void gre_print_0(netdissect_options *, const u_char *, u_int);
+static void gre_print_1(netdissect_options *, const u_char *, u_int);
+static int gre_sre_print(netdissect_options *, uint16_t, uint8_t, uint8_t, const u_char *, u_int);
+static int gre_sre_ip_print(netdissect_options *, uint8_t, uint8_t, const u_char *, u_int);
+static int gre_sre_asn_print(netdissect_options *, uint8_t, uint8_t, const u_char *, u_int);
+
+void
+gre_print(netdissect_options *ndo, const u_char *bp, u_int length)
+{
+ u_int len = length, vers;
+
+ ndo->ndo_protocol = "gre";
+ ND_TCHECK_2(bp);
+ if (len < 2)
+ goto trunc;
+ vers = GET_BE_U_2(bp) & GRE_VERS_MASK;
+ ND_PRINT("GREv%u",vers);
+
+ switch(vers) {
+ case 0:
+ gre_print_0(ndo, bp, len);
+ break;
+ case 1:
+ gre_print_1(ndo, bp, len);
+ break;
+ default:
+ ND_PRINT(" ERROR: unknown-version");
+ break;
+ }
+ return;
+
+trunc:
+ nd_print_trunc(ndo);
+}
+
+static void
+gre_print_0(netdissect_options *ndo, const u_char *bp, u_int length)
+{
+ u_int len = length;
+ uint16_t flags, prot;
+
+ /* 16 bits ND_TCHECKed in gre_print() */
+ flags = GET_BE_U_2(bp);
+ if (ndo->ndo_vflag)
+ ND_PRINT(", Flags [%s]",
+ bittok2str(gre_flag_values,"none",flags));
+
+ len -= 2;
+ bp += 2;
+
+ ND_TCHECK_2(bp);
+ if (len < 2)
+ goto trunc;
+ prot = GET_BE_U_2(bp);
+ len -= 2;
+ bp += 2;
+
+ if ((flags & GRE_CP) | (flags & GRE_RP)) {
+ ND_TCHECK_2(bp);
+ if (len < 2)
+ goto trunc;
+ if (ndo->ndo_vflag)
+ ND_PRINT(", sum 0x%x", GET_BE_U_2(bp));
+ bp += 2;
+ len -= 2;
+
+ ND_TCHECK_2(bp);
+ if (len < 2)
+ goto trunc;
+ ND_PRINT(", off 0x%x", GET_BE_U_2(bp));
+ bp += 2;
+ len -= 2;
+ }
+
+ if (flags & GRE_KP) {
+ ND_TCHECK_4(bp);
+ if (len < 4)
+ goto trunc;
+ ND_PRINT(", key=0x%x", GET_BE_U_4(bp));
+ bp += 4;
+ len -= 4;
+ }
+
+ if (flags & GRE_SP) {
+ ND_TCHECK_4(bp);
+ if (len < 4)
+ goto trunc;
+ ND_PRINT(", seq %u", GET_BE_U_4(bp));
+ bp += 4;
+ len -= 4;
+ }
+
+ if (flags & GRE_RP) {
+ for (;;) {
+ uint16_t af;
+ uint8_t sreoff;
+ uint8_t srelen;
+
+ ND_TCHECK_4(bp);
+ if (len < 4)
+ goto trunc;
+ af = GET_BE_U_2(bp);
+ sreoff = GET_U_1(bp + 2);
+ srelen = GET_U_1(bp + 3);
+ bp += 4;
+ len -= 4;
+
+ if (af == 0 && srelen == 0)
+ break;
+
+ if (!gre_sre_print(ndo, af, sreoff, srelen, bp, len))
+ goto trunc;
+
+ if (len < srelen)
+ goto trunc;
+ bp += srelen;
+ len -= srelen;
+ }
+ }
+
+ if (ndo->ndo_eflag)
+ ND_PRINT(", proto %s (0x%04x)",
+ tok2str(ethertype_values,"unknown",prot), prot);
+
+ ND_PRINT(", length %u",length);
+
+ if (ndo->ndo_vflag < 1)
+ ND_PRINT(": "); /* put in a colon as protocol demarc */
+ else
+ ND_PRINT("\n\t"); /* if verbose go multiline */
+
+ switch (prot) {
+ case ETHERTYPE_IP:
+ ip_print(ndo, bp, len);
+ break;
+ case ETHERTYPE_IPV6:
+ ip6_print(ndo, bp, len);
+ break;
+ case ETHERTYPE_MPLS:
+ mpls_print(ndo, bp, len);
+ break;
+ case ETHERTYPE_IPX:
+ ipx_print(ndo, bp, len);
+ break;
+ case ETHERTYPE_ATALK:
+ atalk_print(ndo, bp, len);
+ break;
+ case ETHERTYPE_GRE_ISO:
+ isoclns_print(ndo, bp, len);
+ break;
+ case ETHERTYPE_TEB:
+ ether_print(ndo, bp, len, ND_BYTES_AVAILABLE_AFTER(bp), NULL, NULL);
+ break;
+ default:
+ ND_PRINT("gre-proto-0x%x", prot);
+ }
+ return;
+
+trunc:
+ nd_print_trunc(ndo);
+}
+
+static void
+gre_print_1(netdissect_options *ndo, const u_char *bp, u_int length)
+{
+ u_int len = length;
+ uint16_t flags, prot;
+
+ /* 16 bits ND_TCHECKed in gre_print() */
+ flags = GET_BE_U_2(bp);
+ len -= 2;
+ bp += 2;
+
+ if (ndo->ndo_vflag)
+ ND_PRINT(", Flags [%s]",
+ bittok2str(gre_flag_values,"none",flags));
+
+ ND_TCHECK_2(bp);
+ if (len < 2)
+ goto trunc;
+ prot = GET_BE_U_2(bp);
+ len -= 2;
+ bp += 2;
+
+
+ if (flags & GRE_KP) {
+ uint32_t k;
+
+ ND_TCHECK_4(bp);
+ if (len < 4)
+ goto trunc;
+ k = GET_BE_U_4(bp);
+ ND_PRINT(", call %u", k & 0xffff);
+ len -= 4;
+ bp += 4;
+ }
+
+ if (flags & GRE_SP) {
+ ND_TCHECK_4(bp);
+ if (len < 4)
+ goto trunc;
+ ND_PRINT(", seq %u", GET_BE_U_4(bp));
+ bp += 4;
+ len -= 4;
+ }
+
+ if (flags & GRE_AP) {
+ ND_TCHECK_4(bp);
+ if (len < 4)
+ goto trunc;
+ ND_PRINT(", ack %u", GET_BE_U_4(bp));
+ bp += 4;
+ len -= 4;
+ }
+
+ if ((flags & GRE_SP) == 0)
+ ND_PRINT(", no-payload");
+
+ if (ndo->ndo_eflag)
+ ND_PRINT(", proto %s (0x%04x)",
+ tok2str(ethertype_values,"unknown",prot), prot);
+
+ ND_PRINT(", length %u",length);
+
+ if ((flags & GRE_SP) == 0)
+ return;
+
+ if (ndo->ndo_vflag < 1)
+ ND_PRINT(": "); /* put in a colon as protocol demarc */
+ else
+ ND_PRINT("\n\t"); /* if verbose go multiline */
+
+ switch (prot) {
+ case ETHERTYPE_PPP:
+ ppp_print(ndo, bp, len);
+ break;
+ default:
+ ND_PRINT("gre-proto-0x%x", prot);
+ break;
+ }
+ return;
+
+trunc:
+ nd_print_trunc(ndo);
+}
+
+static int
+gre_sre_print(netdissect_options *ndo, uint16_t af, uint8_t sreoff,
+ uint8_t srelen, const u_char *bp, u_int len)
+{
+ int ret;
+
+ switch (af) {
+ case GRESRE_IP:
+ ND_PRINT(", (rtaf=ip");
+ ret = gre_sre_ip_print(ndo, sreoff, srelen, bp, len);
+ ND_PRINT(")");
+ break;
+ case GRESRE_ASN:
+ ND_PRINT(", (rtaf=asn");
+ ret = gre_sre_asn_print(ndo, sreoff, srelen, bp, len);
+ ND_PRINT(")");
+ break;
+ default:
+ ND_PRINT(", (rtaf=0x%x)", af);
+ ret = 1;
+ }
+ return (ret);
+}
+
+static int
+gre_sre_ip_print(netdissect_options *ndo, uint8_t sreoff, uint8_t srelen,
+ const u_char *bp, u_int len)
+{
+ const u_char *up = bp;
+ char buf[INET_ADDRSTRLEN];
+
+ if (sreoff & 3) {
+ ND_PRINT(", badoffset=%u", sreoff);
+ return (1);
+ }
+ if (srelen & 3) {
+ ND_PRINT(", badlength=%u", srelen);
+ return (1);
+ }
+ if (sreoff >= srelen) {
+ ND_PRINT(", badoff/len=%u/%u", sreoff, srelen);
+ return (1);
+ }
+
+ while (srelen != 0) {
+ ND_TCHECK_4(bp);
+ if (len < 4)
+ return (0);
+
+ addrtostr(bp, buf, sizeof(buf));
+ ND_PRINT(" %s%s",
+ ((bp - up) == sreoff) ? "*" : "", buf);
+
+ bp += 4;
+ len -= 4;
+ srelen -= 4;
+ }
+ return (1);
+trunc:
+ return 0;
+}
+
+static int
+gre_sre_asn_print(netdissect_options *ndo, uint8_t sreoff, uint8_t srelen,
+ const u_char *bp, u_int len)
+{
+ const u_char *up = bp;
+
+ if (sreoff & 1) {
+ ND_PRINT(", badoffset=%u", sreoff);
+ return (1);
+ }
+ if (srelen & 1) {
+ ND_PRINT(", badlength=%u", srelen);
+ return (1);
+ }
+ if (sreoff >= srelen) {
+ ND_PRINT(", badoff/len=%u/%u", sreoff, srelen);
+ return (1);
+ }
+
+ while (srelen != 0) {
+ ND_TCHECK_2(bp);
+ if (len < 2)
+ return (0);
+
+ ND_PRINT(" %s%x",
+ ((bp - up) == sreoff) ? "*" : "", GET_BE_U_2(bp));
+
+ bp += 2;
+ len -= 2;
+ srelen -= 2;
+ }
+ return (1);
+trunc:
+ return 0;
+}
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