The Tcpdump Group git mirrors - tcpdump/blob - print-vxlan-gpe.c

   1 /* Copyright (c) 2015, bugyo
   2  * All rights reserved.
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions are met:
   6  * 1. Redistributions of source code must retain the above copyright notice,
   7  *    this list of conditions and the following disclaimer.
   8  * 2. Redistributions in binary form must reproduce the above copyright notice,
   9  *    this list of conditions and the following disclaimer in the documentation
  10  *    and/or other materials provided with the distribution.
  11  *
  12  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
  13  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  14  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  15  * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
  16  * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  17  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  18  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  19  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  20  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  21  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  22  */
  23
  24 /* \summary: Generic Protocol Extension for VXLAN (VXLAN GPE) printer */
  25
  26 /* specification: draft-ietf-nvo3-vxlan-gpe-12 */
  27
  28 #include <config.h>
  29
  30 #include "netdissect-stdinc.h"
  31
  32 #define ND_LONGJMP_FROM_TCHECK
  33 #include "netdissect.h"
  34 #include "extract.h"
  35
  36 #define VXLAN_GPE_VER   0x30 /* GPE */
  37 #define VXLAN_GPE_SHIFT 4
  38 #define VXLAN_GPE_VER_0 0x0
  39 #define VXLAN_GPE_I     0x08 /* Instance Bit */
  40 #define VXLAN_GPE_P     0x04 /* GPE Next Protocol */
  41 #define VXLAN_GPE_B     0x02 /* GPE BUM Traffic */
  42 #define VXLAN_GPE_O     0x01 /* GPE OAM Flag */
  43
  44 static const struct tok vxlan_gpe_flags [] = {
  45     { VXLAN_GPE_I, "I" },
  46     { VXLAN_GPE_P, "P" },
  47     { VXLAN_GPE_B, "B" },
  48     { VXLAN_GPE_O, "O" },
  49     { 0, NULL }
  50 };
  51
  52 #define VXLAN_GPE_PROTO_RESERVED 0x00
  53 #define VXLAN_GPE_PROTO_IPV4     0x01
  54 #define VXLAN_GPE_PROTO_IPV6     0x02
  55 #define VXLAN_GPE_PROTO_ETHERNET 0x03
  56 #define VXLAN_GPE_PROTO_NSH      0x04
  57
  58 #define VXLAN_GPE_HDR_LEN 8
  59
  60 /*
  61  * VXLAN GPE header, draft-ietf-nvo3-vxlan-gpe-12
  62  *                   Generic Protocol Extension for VXLAN
  63  *
  64  *     0                   1                   2                   3
  65  *     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
  66  *    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  67  *    |R|R|Ver|I|P|B|O|       Reserved                |Next Protocol  |
  68  *    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  69  *    |                VXLAN Network Identifier (VNI) |   Reserved    |
  70  *    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  71  */
  72
  73 void
  74 vxlan_gpe_print(netdissect_options *ndo, const u_char *bp, u_int len)
  75 {
  76     uint8_t flags, ver;
  77     uint8_t next_protocol;
  78
  79     /*
  80      * XXX - OpenBSD has a single dissector for VXLAN and VXLAN-GPE,
  81      * using the flag bits to distinguish between them.
  82      *
  83      * draft-ietf-nvo3-vxlan-gpe-12, the final VXLAN-GPE draft, says
  84      * that VXLAN-GPE uses port 4790, rather than VXLAN's port 4789,
  85      * and that the P flag bit must be set for VXLAN-GPE packets,
  86      * indicating that the header includes a "next protocol" field,
  87      * and that if a packet with the P it not set is received on
  88      * port 4790, "the "Next Protocol" field must be set to zero and
  89      * the payload MUST be ETHERNET(L2) as defined by [RFC7348]."
  90      */
  91     ndo->ndo_protocol = "vxlan_gpe";
  92     ND_PRINT("VXLAN-GPE, ");
  93     if (len < VXLAN_GPE_HDR_LEN) {
  94         ND_PRINT(" (len %u < %u)", len, VXLAN_GPE_HDR_LEN);
  95         goto invalid;
  96     }
  97
  98     flags = GET_U_1(bp);
  99     bp += 1;
 100     len -= 1;
 101     ver = (flags & VXLAN_GPE_VER) >> VXLAN_GPE_SHIFT;
 102     if (ver != VXLAN_GPE_VER_0) {
 103         ND_PRINT("unknown version %u", ver);
 104         goto invalid;
 105     }
 106     ND_PRINT("flags [%s], ",
 107               bittok2str_nosep(vxlan_gpe_flags, "none", flags));
 108
 109     /* Reserved */
 110     bp += 2;
 111     len -= 2;
 112
 113     /*
 114      * If the VXLAN_GPE_P flag bit isn't set, that means this is a VXLAN
 115      * packet, not a VXLAN-GPE packet, and thus has no "next protocol"
 116      * field; the payload is Ethernet.
 117      */
 118     if (flags & VXLAN_GPE_P)
 119         next_protocol = GET_U_1(bp);
 120     else
 121         next_protocol = VXLAN_GPE_PROTO_ETHERNET;
 122     bp += 1;
 123     len -= 1;
 124
 125     /*
 126      * Both RFC 7348 and draft-ietf-nvo3-vxlan-gpe-12 say that the I flag
 127      * MUST be set.
 128      */
 129     if (flags & VXLAN_GPE_I)
 130         ND_PRINT("vni %u", GET_BE_U_3(bp));
 131     else
 132         ND_PRINT("ERROR: I flag not set");
 133     bp += 3;
 134     len -= 3;
 135
 136     if (flags & VXLAN_GPE_B)
 137         ND_PRINT(", BUM");
 138
 139     if (flags & VXLAN_GPE_O) {
 140         ND_PRINT(", OAM (proto 0x%x, len %u)", next_protocol, len);
 141         return;
 142     }
 143
 144     /* Reserved */
 145     ND_TCHECK_1(bp);
 146     bp += 1;
 147     len -= 1;
 148
 149     ND_PRINT(ndo->ndo_vflag ? "\n    " : ": ");
 150
 151     switch (next_protocol) {
 152     case VXLAN_GPE_PROTO_IPV4:
 153         ip_print(ndo, bp, len);
 154         break;
 155     case VXLAN_GPE_PROTO_IPV6:
 156         ip6_print(ndo, bp, len);
 157         break;
 158     case VXLAN_GPE_PROTO_ETHERNET:
 159         ether_print(ndo, bp, len, ND_BYTES_AVAILABLE_AFTER(bp), NULL, NULL);
 160         break;
 161     case VXLAN_GPE_PROTO_NSH:
 162         nsh_print(ndo, bp, len);
 163         break;
 164     /*
 165      * OpenBSD supports 0x05 for MPLS, which was in earlier drafts
 166      * of VXLAN GPE, but not in the final -12 draft.
 167      */
 168     default:
 169         ND_PRINT("ERROR: unknown-next-protocol");
 170         goto invalid;
 171     }
 172
 173     return;
 174
 175 invalid:
 176     nd_print_invalid(ndo);
 177 }
 178