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 #ifdef HAVE_CONFIG_H
  21 #include <config.h>
  22 #endif
  23
  24 #include "netdissect-stdinc.h"
  25
  26 #define ND_LONGJMP_FROM_TCHECK
  27 #include "netdissect.h"
  28 #include "extract.h"
  29
  30 #define VXLAN_I     0x08 /* Instance Bit */
  31
  32 static const struct tok vxlan_flags [] = {
  33     { VXLAN_I, "I" },
  34     { 0, NULL }
  35 };
  36 #define VXLAN_HDR_LEN 8
  37
  38 /*
  39  * VXLAN header, RFC7348
  40  *               Virtual eXtensible Local Area Network (VXLAN): A Framework
  41  *               for Overlaying Virtualized Layer 2 Networks over Layer 3 Networks
  42  *
  43  *     0                   1                   2                   3
  44  *     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
  45  *    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  46  *    |R|R|R|R|I|R|R|R|            Reserved                           |
  47  *    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  48  *    |                VXLAN Network Identifier (VNI) |   Reserved    |
  49  *    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  50  */
  51
  52 void
  53 vxlan_print(netdissect_options *ndo, const u_char *bp, u_int len)
  54 {
  55     uint8_t flags;
  56
  57     ndo->ndo_protocol = "vxlan";
  58     nd_print_protocol_caps(ndo);
  59     if (len < VXLAN_HDR_LEN)
  60         goto invalid;
  61
  62     flags = GET_U_1(bp);
  63     bp += 1;
  64     ND_PRINT(", flags [%s] (0x%02x), ",
  65              bittok2str_nosep(vxlan_flags, "invalid", flags), flags);
  66
  67     /* 1st Reserved */
  68     bp += 3;
  69
  70     /*
  71      * RFC 7348 says that the I flag MUST be set.
  72      */
  73     if (flags & VXLAN_I)
  74         ND_PRINT("vni %u\n", GET_BE_U_3(bp));
  75     else
  76         ND_PRINT("ERROR: I flag not set\n");
  77     bp += 3;
  78
  79     /* 2nd Reserved */
  80     ND_TCHECK_1(bp);
  81     bp += 1;
  82
  83     ether_print(ndo, bp, len - VXLAN_HDR_LEN, ND_BYTES_AVAILABLE_AFTER(bp), NULL, NULL);
  84
  85     return;
  86
  87 invalid:
  88     nd_print_invalid(ndo);
  89 }