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

   1 /*
   2  * Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 2000
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that: (1) source code distributions
   7  * retain the above copyright notice and this paragraph in its entirety, (2)
   8  * distributions including binary code include the above copyright notice and
   9  * this paragraph in its entirety in the documentation or other materials
  10  * provided with the distribution, and (3) all advertising materials mentioning
  11  * features or use of this software display the following acknowledgement:
  12  * ``This product includes software developed by the University of California,
  13  * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
  14  * the University nor the names of its contributors may be used to endorse
  15  * or promote products derived from this software without specific prior
  16  * written permission.
  17  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
  18  * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
  19  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  20  */
  21
  22 /* \summary: Apple's DLT_PKTAP printer */
  23
  24 #include <config.h>
  25
  26 #include "netdissect-stdinc.h"
  27
  28 #define ND_LONGJMP_FROM_TCHECK
  29 #include "netdissect.h"
  30 #include "extract.h"
  31
  32 #ifdef DLT_PKTAP
  33
  34 /*
  35  * XXX - these are little-endian in the captures I've seen, but Apple
  36  * no longer make any big-endian machines (Macs use x86, iOS machines
  37  * use ARM and run it little-endian), so that might be by definition
  38  * or they might be host-endian.
  39  *
  40  * If a big-endian PKTAP file ever shows up, and it comes from a
  41  * big-endian machine, presumably these are host-endian, and we need
  42  * to just fetch the fields directly in tcpdump but byte-swap them
  43  * to host byte order in libpcap.
  44  */
  45 typedef struct pktap_header {
  46         nd_uint32_t     pkt_len;        /* length of pktap header */
  47         nd_uint32_t     pkt_rectype;    /* type of record */
  48         nd_uint32_t     pkt_dlt;        /* DLT type of this packet */
  49         char            pkt_ifname[24]; /* interface name */
  50         nd_uint32_t     pkt_flags;
  51         nd_uint32_t     pkt_pfamily;    /* "protocol family" */
  52         nd_uint32_t     pkt_llhdrlen;   /* link-layer header length? */
  53         nd_uint32_t     pkt_lltrlrlen;  /* link-layer trailer length? */
  54         nd_uint32_t     pkt_pid;        /* process ID */
  55         char            pkt_cmdname[20]; /* command name */
  56         nd_uint32_t     pkt_svc_class;  /* "service class" */
  57         nd_uint16_t     pkt_iftype;     /* "interface type" */
  58         nd_uint16_t     pkt_ifunit;     /* unit number of interface? */
  59         nd_uint32_t     pkt_epid;       /* "effective process ID" */
  60         char            pkt_ecmdname[20]; /* "effective command name" */
  61 } pktap_header_t;
  62
  63 /*
  64  * Record types.
  65  */
  66 #define PKT_REC_NONE    0       /* nothing follows the header */
  67 #define PKT_REC_PACKET  1       /* a packet follows the header */
  68
  69 static void
  70 pktap_header_print(netdissect_options *ndo, const u_char *bp, u_int length)
  71 {
  72         const pktap_header_t *hdr;
  73         uint32_t dlt, hdrlen;
  74         const char *dltname;
  75
  76         hdr = (const pktap_header_t *)bp;
  77
  78         dlt = GET_LE_U_4(hdr->pkt_dlt);
  79         hdrlen = GET_LE_U_4(hdr->pkt_len);
  80         dltname = pcap_datalink_val_to_name(dlt);
  81         if (!ndo->ndo_qflag) {
  82                 ND_PRINT("DLT %s (%u) len %u",
  83                           (dltname != NULL ? dltname : "UNKNOWN"), dlt, hdrlen);
  84         } else {
  85                 ND_PRINT("%s", (dltname != NULL ? dltname : "UNKNOWN"));
  86         }
  87
  88         ND_PRINT(", length %u: ", length);
  89 }
  90
  91 /*
  92  * This is the top level routine of the printer.  'p' points
  93  * to the ether header of the packet, 'h->ts' is the timestamp,
  94  * 'h->len' is the length of the packet off the wire, and 'h->caplen'
  95  * is the number of bytes actually captured.
  96  */
  97 void
  98 pktap_if_print(netdissect_options *ndo,
  99                const struct pcap_pkthdr *h, const u_char *p)
 100 {
 101         uint32_t dlt, hdrlen, rectype;
 102         u_int caplen = h->caplen;
 103         u_int length = h->len;
 104         if_printer printer;
 105         const pktap_header_t *hdr;
 106         struct pcap_pkthdr nhdr;
 107
 108         ndo->ndo_protocol = "pktap";
 109         if (length < sizeof(pktap_header_t)) {
 110                 ND_PRINT(" (packet too short, %u < %zu)",
 111                          length, sizeof(pktap_header_t));
 112                 goto invalid;
 113         }
 114         hdr = (const pktap_header_t *)p;
 115         dlt = GET_LE_U_4(hdr->pkt_dlt);
 116         hdrlen = GET_LE_U_4(hdr->pkt_len);
 117         if (hdrlen < sizeof(pktap_header_t)) {
 118                 /*
 119                  * Claimed header length < structure length.
 120                  * XXX - does this just mean some fields aren't
 121                  * being supplied, or is it truly an error (i.e.,
 122                  * is the length supplied so that the header can
 123                  * be expanded in the future)?
 124                  */
 125                 ND_PRINT(" (pkt_len too small, %u < %zu)",
 126                          hdrlen, sizeof(pktap_header_t));
 127                 goto invalid;
 128         }
 129         if (hdrlen > length) {
 130                 ND_PRINT(" (pkt_len too big, %u > %u)",
 131                          hdrlen, length);
 132                 goto invalid;
 133         }
 134         ND_TCHECK_LEN(p, hdrlen);
 135
 136         if (ndo->ndo_eflag)
 137                 pktap_header_print(ndo, p, length);
 138
 139         length -= hdrlen;
 140         caplen -= hdrlen;
 141         p += hdrlen;
 142
 143         rectype = GET_LE_U_4(hdr->pkt_rectype);
 144         switch (rectype) {
 145
 146         case PKT_REC_NONE:
 147                 ND_PRINT("no data");
 148                 break;
 149
 150         case PKT_REC_PACKET:
 151                 printer = lookup_printer(dlt);
 152                 if (printer != NULL) {
 153                         nhdr = *h;
 154                         nhdr.caplen = caplen;
 155                         nhdr.len = length;
 156                         printer(ndo, &nhdr, p);
 157                         hdrlen += ndo->ndo_ll_hdr_len;
 158                 } else {
 159                         if (!ndo->ndo_eflag)
 160                                 pktap_header_print(ndo, (const u_char *)hdr,
 161                                                 length + hdrlen);
 162
 163                         if (!ndo->ndo_suppress_default_print)
 164                                 ND_DEFAULTPRINT(p, caplen);
 165                 }
 166                 break;
 167         }
 168
 169         ndo->ndo_ll_hdr_len += hdrlen;
 170         return;
 171
 172 invalid:
 173         nd_print_invalid(ndo);
 174 }
 175 #endif /* DLT_PKTAP */