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

   1 /*
   2  * Redistribution and use in source and binary forms, with or without
   3  * modification, are permitted provided that: (1) source code
   4  * distributions retain the above copyright notice and this paragraph
   5  * in its entirety, and (2) distributions including binary code include
   6  * the above copyright notice and this paragraph in its entirety in
   7  * the documentation or other materials provided with the distribution.
   8  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND
   9  * WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, WITHOUT
  10  * LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  11  * FOR A PARTICULAR PURPOSE.
  12  *
  13  * Original code by Francesco Fondelli (francesco dot fondelli, gmail dot com)
  14  */
  15
  16 /* \summary: Virtual eXtensible Local Area Network (VXLAN) printer */
  17
  18 /* specification: RFC 7348 */
  19
  20 #include <config.h>
  21
  22 #include "netdissect-stdinc.h"
  23
  24 #define ND_LONGJMP_FROM_TCHECK
  25 #include "netdissect.h"
  26 #include "extract.h"
  27
  28 #define VXLAN_I     0x08 /* Instance Bit */
  29
  30 static const struct tok vxlan_flags [] = {
  31     { VXLAN_I, "I" },
  32     { 0, NULL }
  33 };
  34 #define VXLAN_HDR_LEN 8
  35
  36 /*
  37  * VXLAN header, RFC7348
  38  *               Virtual eXtensible Local Area Network (VXLAN): A Framework
  39  *               for Overlaying Virtualized Layer 2 Networks over Layer 3 Networks
  40  *
  41  *     0                   1                   2                   3
  42  *     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
  43  *    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  44  *    |R|R|R|R|I|R|R|R|            Reserved                           |
  45  *    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  46  *    |                VXLAN Network Identifier (VNI) |   Reserved    |
  47  *    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  48  */
  49
  50 void
  51 vxlan_print(netdissect_options *ndo, const u_char *bp, u_int len)
  52 {
  53     uint8_t flags;
  54
  55     ndo->ndo_protocol = "vxlan";
  56     nd_print_protocol_caps(ndo);
  57     if (len < VXLAN_HDR_LEN)
  58         goto invalid;
  59
  60     flags = GET_U_1(bp);
  61     bp += 1;
  62     ND_PRINT(", flags [%s] (0x%02x), ",
  63              bittok2str_nosep(vxlan_flags, "invalid", flags), flags);
  64
  65     /* 1st Reserved */
  66     bp += 3;
  67
  68     /*
  69      * RFC 7348 says that the I flag MUST be set.
  70      */
  71     if (flags & VXLAN_I)
  72         ND_PRINT("vni %u\n", GET_BE_U_3(bp));
  73     else
  74         ND_PRINT("ERROR: I flag not set\n");
  75     bp += 3;
  76
  77     /* 2nd Reserved */
  78     ND_TCHECK_1(bp);
  79     bp += 1;
  80
  81     ether_print(ndo, bp, len - VXLAN_HDR_LEN, ND_BYTES_AVAILABLE_AFTER(bp), NULL, NULL);
  82
  83     return;
  84
  85 invalid:
  86     nd_print_invalid(ndo);
  87 }