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

   1 /*      $OpenBSD: print-enc.c,v 1.7 2002/02/19 19:39:40 millert Exp $   */
   2
   3 /*
   4  * Copyright (c) 1990, 1991, 1993, 1994, 1995, 1996
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that: (1) source code distributions
   9  * retain the above copyright notice and this paragraph in its entirety, (2)
  10  * distributions including binary code include the above copyright notice and
  11  * this paragraph in its entirety in the documentation or other materials
  12  * provided with the distribution, and (3) all advertising materials mentioning
  13  * features or use of this software display the following acknowledgement:
  14  * ``This product includes software developed by the University of California,
  15  * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
  16  * the University nor the names of its contributors may be used to endorse
  17  * or promote products derived from this software without specific prior
  18  * written permission.
  19  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
  20  * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
  21  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  22  */
  23
  24 /* \summary: OpenBSD IPsec encapsulation BPF layer printer */
  25
  26 #include <config.h>
  27
  28 #include "netdissect-stdinc.h"
  29
  30 #define ND_LONGJMP_FROM_TCHECK
  31 #include "netdissect.h"
  32 #include "extract.h"
  33 #include "af.h"
  34
  35 /* From $OpenBSD: if_enc.h,v 1.8 2001/06/25 05:14:00 angelos Exp $ */
  36 /*
  37  * The authors of this code are John Ioannidis (ji@tla.org),
  38  * Angelos D. Keromytis (kermit@csd.uch.gr) and
  39  * Niels Provos (provos@physnet.uni-hamburg.de).
  40  *
  41  * This code was written by John Ioannidis for BSD/OS in Athens, Greece,
  42  * in November 1995.
  43  *
  44  * Ported to OpenBSD and NetBSD, with additional transforms, in December 1996,
  45  * by Angelos D. Keromytis.
  46  *
  47  * Additional transforms and features in 1997 and 1998 by Angelos D. Keromytis
  48  * and Niels Provos.
  49  *
  50  * Copyright (C) 1995, 1996, 1997, 1998 by John Ioannidis, Angelos D. Keromytis
  51  * and Niels Provos.
  52  * Copyright (c) 2001, Angelos D. Keromytis.
  53  *
  54  * Permission to use, copy, and modify this software with or without fee
  55  * is hereby granted, provided that this entire notice is included in
  56  * all copies of any software which is or includes a copy or
  57  * modification of this software.
  58  * You may use this code under the GNU public license if you so wish. Please
  59  * contribute changes back to the authors under this freer than GPL license
  60  * so that we may further the use of strong encryption without limitations to
  61  * all.
  62  *
  63  * THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR
  64  * IMPLIED WARRANTY. IN PARTICULAR, NONE OF THE AUTHORS MAKES ANY
  65  * REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE
  66  * MERCHANTABILITY OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR
  67  * PURPOSE.
  68  */
  69
  70 #define ENC_HDRLEN      12
  71
  72 /* From $OpenBSD: mbuf.h,v 1.56 2002/01/25 15:50:23 art Exp $   */
  73 #define M_CONF          0x0400  /* packet was encrypted (ESP-transport) */
  74 #define M_AUTH          0x0800  /* packet was authenticated (AH) */
  75
  76 struct enchdr {
  77         nd_uint32_t af;
  78         nd_uint32_t spi;
  79         nd_uint32_t flags;
  80 };
  81
  82 #define ENC_PRINT_TYPE(wh, xf, name) \
  83         if ((wh) & (xf)) { \
  84                 ND_PRINT("%s%s", name, (wh) == (xf) ? "): " : ","); \
  85                 (wh) &= ~(xf); \
  86         }
  87
  88 /*
  89  * Byte-swap a 32-bit number.
  90  * ("htonl()" or "ntohl()" won't work - we want to byte-swap even on
  91  * big-endian platforms.)
  92  */
  93 #define SWAPLONG(y) \
  94 ((((y)&0xff)<<24) | (((y)&0xff00)<<8) | (((y)&0xff0000)>>8) | (((y)>>24)&0xff))
  95
  96 void
  97 enc_if_print(netdissect_options *ndo,
  98              const struct pcap_pkthdr *h, const u_char *p)
  99 {
 100         u_int length = h->len;
 101         u_int af, flags;
 102         const struct enchdr *hdr;
 103
 104         ndo->ndo_protocol = "enc";
 105         ND_TCHECK_LEN(p, ENC_HDRLEN);
 106         ndo->ndo_ll_hdr_len += ENC_HDRLEN;
 107
 108         hdr = (const struct enchdr *)p;
 109         /*
 110          * The address family and flags fields are in the byte order
 111          * of the host that originally captured the traffic.
 112          *
 113          * To determine that, look at the address family.  It's 32-bit,
 114          * it is not likely ever to be > 65535 (I doubt there will
 115          * ever be > 65535 address families and, so far, AF_ values have
 116          * not been allocated very sparsely) so it should not have the
 117          * upper 16 bits set, and it is not likely ever to be AF_UNSPEC,
 118          * i.e. it's not likely ever to be 0, so if it's byte-swapped,
 119          * it should have at least one of the upper 16 bits set.
 120          *
 121          * So if any of the upper 16 bits are set, we assume it, and
 122          * the flags field, are byte-swapped.
 123          *
 124          * The SPI field is always in network byte order, i.e. big-
 125          * endian.
 126          */
 127         UNALIGNED_MEMCPY(&af, &hdr->af, sizeof (af));
 128         UNALIGNED_MEMCPY(&flags, &hdr->flags, sizeof (flags));
 129         if ((af & 0xFFFF0000) != 0) {
 130                 af = SWAPLONG(af);
 131                 flags = SWAPLONG(flags);
 132         }
 133
 134         if (flags == 0)
 135                 ND_PRINT("(unprotected): ");
 136         else
 137                 ND_PRINT("(");
 138         ENC_PRINT_TYPE(flags, M_AUTH, "authentic");
 139         ENC_PRINT_TYPE(flags, M_CONF, "confidential");
 140         /* ENC_PRINT_TYPE(flags, M_TUNNEL, "tunnel"); */
 141         ND_PRINT("SPI 0x%08x: ", GET_BE_U_4(hdr->spi));
 142
 143         length -= ENC_HDRLEN;
 144         p += ENC_HDRLEN;
 145
 146         switch (af) {
 147         case BSD_AF_INET:
 148                 ip_print(ndo, p, length);
 149                 break;
 150         case BSD_AF_INET6_BSD:
 151         case BSD_AF_INET6_FREEBSD:
 152         case BSD_AF_INET6_DARWIN:
 153                 ip6_print(ndo, p, length);
 154                 break;
 155         }
 156 }