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 #ifdef HAVE_CONFIG_H
  27 #include <config.h>
  28 #endif
  29
  30 #include "netdissect-stdinc.h"
  31
  32 #include "netdissect.h"
  33 #include "extract.h"
  34 #include "af.h"
  35
  36 /* From $OpenBSD: if_enc.h,v 1.8 2001/06/25 05:14:00 angelos Exp $ */
  37 /*
  38  * The authors of this code are John Ioannidis (ji@tla.org),
  39  * Angelos D. Keromytis (kermit@csd.uch.gr) and
  40  * Niels Provos (provos@physnet.uni-hamburg.de).
  41  *
  42  * This code was written by John Ioannidis for BSD/OS in Athens, Greece,
  43  * in November 1995.
  44  *
  45  * Ported to OpenBSD and NetBSD, with additional transforms, in December 1996,
  46  * by Angelos D. Keromytis.
  47  *
  48  * Additional transforms and features in 1997 and 1998 by Angelos D. Keromytis
  49  * and Niels Provos.
  50  *
  51  * Copyright (C) 1995, 1996, 1997, 1998 by John Ioannidis, Angelos D. Keromytis
  52  * and Niels Provos.
  53  * Copyright (c) 2001, Angelos D. Keromytis.
  54  *
  55  * Permission to use, copy, and modify this software with or without fee
  56  * is hereby granted, provided that this entire notice is included in
  57  * all copies of any software which is or includes a copy or
  58  * modification of this software.
  59  * You may use this code under the GNU public license if you so wish. Please
  60  * contribute changes back to the authors under this freer than GPL license
  61  * so that we may further the use of strong encryption without limitations to
  62  * all.
  63  *
  64  * THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR
  65  * IMPLIED WARRANTY. IN PARTICULAR, NONE OF THE AUTHORS MAKES ANY
  66  * REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE
  67  * MERCHANTABILITY OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR
  68  * PURPOSE.
  69  */
  70
  71 #define ENC_HDRLEN      12
  72
  73 /* From $OpenBSD: mbuf.h,v 1.56 2002/01/25 15:50:23 art Exp $   */
  74 #define M_CONF          0x0400  /* packet was encrypted (ESP-transport) */
  75 #define M_AUTH          0x0800  /* packet was authenticated (AH) */
  76
  77 struct enchdr {
  78         nd_uint32_t af;
  79         nd_uint32_t spi;
  80         nd_uint32_t flags;
  81 };
  82
  83 #define ENC_PRINT_TYPE(wh, xf, nam) \
  84         if ((wh) & (xf)) { \
  85                 ND_PRINT("%s%s", nam, (wh) == (xf) ? "): " : ","); \
  86                 (wh) &= ~(xf); \
  87         }
  88
  89 /*
  90  * Byte-swap a 32-bit number.
  91  * ("htonl()" or "ntohl()" won't work - we want to byte-swap even on
  92  * big-endian platforms.)
  93  */
  94 #define SWAPLONG(y) \
  95 ((((y)&0xff)<<24) | (((y)&0xff00)<<8) | (((y)&0xff0000)>>8) | (((y)>>24)&0xff))
  96
  97 void
  98 enc_if_print(netdissect_options *ndo,
  99              const struct pcap_pkthdr *h, const u_char *p)
 100 {
 101         u_int length = h->len;
 102         u_int caplen = h->caplen;
 103         u_int af, flags;
 104         const struct enchdr *hdr;
 105
 106         ndo->ndo_protocol = "enc";
 107         if (caplen < ENC_HDRLEN) {
 108                 ndo->ndo_ll_header_length += caplen;
 109                 nd_print_trunc(ndo);
 110                 return;
 111         }
 112         ndo->ndo_ll_header_length += ENC_HDRLEN;
 113
 114         hdr = (const struct enchdr *)p;
 115         /*
 116          * The address family and flags fields are in the byte order
 117          * of the host that originally captured the traffic.
 118          *
 119          * To determine that, look at the address family.  It's 32-bit,
 120          * it is not likely ever to be > 65535 (I doubt there will
 121          * ever be > 65535 address families and, so far, AF_ values have
 122          * not been allocated very sparsely) so it should not have the
 123          * upper 16 bits set, and it is not likely ever to be AF_UNSPEC,
 124          * i.e. it's not likely ever to be 0, so if it's byte-swapped,
 125          * it should have at least one of the upper 16 bits set.
 126          *
 127          * So if any of the upper 16 bits are set, we assume it, and
 128          * the flags field, are byte-swapped.
 129          *
 130          * The SPI field is always in network byte order, i.e. big-
 131          * endian.
 132          */
 133         UNALIGNED_MEMCPY(&af, &hdr->af, sizeof (af));
 134         UNALIGNED_MEMCPY(&flags, &hdr->flags, sizeof (flags));
 135         if ((af & 0xFFFF0000) != 0) {
 136                 af = SWAPLONG(af);
 137                 flags = SWAPLONG(flags);
 138         }
 139
 140         if (flags == 0)
 141                 ND_PRINT("(unprotected): ");
 142         else
 143                 ND_PRINT("(");
 144         ENC_PRINT_TYPE(flags, M_AUTH, "authentic");
 145         ENC_PRINT_TYPE(flags, M_CONF, "confidential");
 146         /* ENC_PRINT_TYPE(flags, M_TUNNEL, "tunnel"); */
 147         ND_PRINT("SPI 0x%08x: ", GET_BE_U_4(hdr->spi));
 148
 149         length -= ENC_HDRLEN;
 150         caplen -= ENC_HDRLEN;
 151         p += ENC_HDRLEN;
 152
 153         switch (af) {
 154         case BSD_AFNUM_INET:
 155                 ip_print(ndo, p, length);
 156                 break;
 157         case BSD_AFNUM_INET6_BSD:
 158         case BSD_AFNUM_INET6_FREEBSD:
 159         case BSD_AFNUM_INET6_DARWIN:
 160                 ip6_print(ndo, p, length);
 161                 break;
 162         }
 163
 164         return;
 165 }