frame_tvbuff.c

   1 /* frame_tvbuff.c
   2  * Implements a tvbuff for frame
   3  *
   4  * $Id$
   5  *
   6  * Wireshark - Network traffic analyzer
   7  * By Gerald Combs <gerald@wireshark.org>
   8  * Copyright 1998 Gerald Combs
   9  *
  10  * This program is free software; you can redistribute it and/or
  11  * modify it under the terms of the GNU General Public License
  12  * as published by the Free Software Foundation; either version 2
  13  * of the License, or (at your option) any later version.
  14  *
  15  * This program is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18  * GNU General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public License
  21  * along with this program; if not, write to the Free Software
  22  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  23  */
  24
  25 #include "config.h"
  26
  27 #include <glib.h>
  28
  29 #include <epan/packet.h>
  30 #include <epan/tvbuff-int.h>
  31 #include <epan/tvbuff.h>
  32
  33 #include "frame_tvbuff.h"
  34 #include "globals.h"
  35
  36 #include "wtap-int.h" /* for ->random_fh */
  37
  38 struct tvb_frame {
  39         struct tvbuff tvb;
  40
  41         Buffer *buf;         /* Packet data */
  42
  43         wtap *wth;           /**< Wiretap session */
  44         gint64 file_off;     /**< File offset */
  45
  46         guint offset;
  47 };
  48
  49 static gboolean
  50 frame_read(struct tvb_frame *frame_tvb, struct wtap_pkthdr *phdr, Buffer *buf)
  51 {
  52         int    err;
  53         gchar *err_info;
  54
  55         /* sanity check, capture file was closed? */
  56         if (cfile.wth != frame_tvb->wth)
  57                 return FALSE;
  58
  59         /* XXX, frame_tvb->tvb.length + frame_tvb->offset might be not real captured packet length
  60          *      can it cause some problems for wiretap readers?
  61          */
  62         if (!wtap_seek_read(frame_tvb->wth, frame_tvb->file_off, phdr, buf, frame_tvb->tvb.length + frame_tvb->offset, &err, &err_info)) {
  63                 switch (err) {
  64                         case WTAP_ERR_UNSUPPORTED_ENCAP:
  65                         case WTAP_ERR_BAD_FILE:
  66                                 g_free(err_info);
  67                                 break;
  68                 }
  69                 return FALSE;
  70         }
  71         return TRUE;
  72 }
  73
  74 static void
  75 frame_cache(struct tvb_frame *frame_tvb)
  76 {
  77         struct wtap_pkthdr phdr; /* Packet header */
  78
  79         if (frame_tvb->buf == NULL) {
  80                 frame_tvb->buf = (struct Buffer *) g_malloc(sizeof(struct Buffer));
  81
  82                 /* XXX, register frame_tvb to some list which frees from time to time not used buffers :] */
  83                 buffer_init(frame_tvb->buf, frame_tvb->tvb.length + frame_tvb->offset);
  84
  85                 if (!frame_read(frame_tvb, &phdr, frame_tvb->buf))
  86                         { /* TODO: THROW(???); */ }
  87         }
  88
  89         frame_tvb->tvb.real_data = buffer_start_ptr(frame_tvb->buf) + frame_tvb->offset;
  90 }
  91
  92 static void
  93 frame_free(tvbuff_t *tvb)
  94 {
  95         struct tvb_frame *frame_tvb = (struct tvb_frame *) tvb;
  96
  97         if (frame_tvb->buf) {
  98                 buffer_free(frame_tvb->buf);
  99
 100                 g_free(frame_tvb->buf);
 101         }
 102 }
 103
 104 static const guint8 *
 105 frame_get_ptr(tvbuff_t *tvb, guint abs_offset, guint abs_length _U_)
 106 {
 107         struct tvb_frame *frame_tvb = (struct tvb_frame *) tvb;
 108
 109         frame_cache(frame_tvb);
 110
 111         return tvb->real_data + abs_offset;
 112 }
 113
 114 static void *
 115 frame_memcpy(tvbuff_t *tvb, void *target, guint abs_offset, guint abs_length)
 116 {
 117         struct tvb_frame *frame_tvb = (struct tvb_frame *) tvb;
 118
 119         frame_cache(frame_tvb);
 120
 121         return memcpy(target, tvb->real_data + abs_offset, abs_length);
 122 }
 123
 124 static gint
 125 frame_find_guint8(tvbuff_t *tvb, guint abs_offset, guint limit, guint8 needle)
 126 {
 127         struct tvb_frame *frame_tvb = (struct tvb_frame *) tvb;
 128         const guint8 *result;
 129
 130         frame_cache(frame_tvb);
 131
 132         result = (const guint8 *)memchr(tvb->real_data + abs_offset, needle, limit);
 133         if (result)
 134                 return (gint) (result - tvb->real_data);
 135         else
 136                 return -1;
 137 }
 138
 139 static gint
 140 frame_pbrk_guint8(tvbuff_t *tvb, guint abs_offset, guint limit, const guint8 *needles, guchar *found_needle)
 141 {
 142         struct tvb_frame *frame_tvb = (struct tvb_frame *) tvb;
 143
 144         frame_cache(frame_tvb);
 145
 146         return tvb_pbrk_guint8(tvb, abs_offset, limit, needles, found_needle);
 147 }
 148
 149 static guint
 150 frame_offset(const tvbuff_t *tvb _U_, const guint counter)
 151 {
 152         /* XXX: frame_tvb->offset */
 153         return counter;
 154 }
 155
 156 static tvbuff_t *frame_clone(tvbuff_t *tvb, guint abs_offset, guint abs_length);
 157
 158 static const struct tvb_ops tvb_frame_ops = {
 159         sizeof(struct tvb_frame), /* size */
 160
 161         frame_free,           /* free */
 162         frame_offset,         /* offset */
 163         frame_get_ptr,        /* get_ptr */
 164         frame_memcpy,         /* memcpy */
 165         frame_find_guint8,    /* find_guint8 */
 166         frame_pbrk_guint8,    /* pbrk_guint8 */
 167         frame_clone,          /* clone */
 168 };
 169
 170 /* based on tvb_new_real_data() */
 171 tvbuff_t *
 172 frame_tvbuff_new(const frame_data *fd, const guint8 *buf)
 173 {
 174         struct tvb_frame *frame_tvb;
 175         tvbuff_t *tvb;
 176
 177         tvb = tvb_new(&tvb_frame_ops);
 178
 179         /*
 180          * XXX - currently, the length arguments in
 181          * tvbuff structure are signed, but the captured
 182          * and reported length values are unsigned; this means
 183          * that length values > 2^31 - 1 will appear as
 184          * negative lengths
 185          *
 186          * Captured length values that large will already
 187          * have been filtered out by the Wiretap modules
 188          * (the file will be reported as corrupted), to
 189          * avoid trying to allocate large chunks of data.
 190          *
 191          * Reported length values will not have been
 192          * filtered out, and should not be filtered out,
 193          * as those lengths are not necessarily invalid.
 194          *
 195          * For now, we clip the reported length at G_MAXINT
 196          *
 197          * (XXX, is this still a problem?) There was an exception when we call
 198          * tvb_new_real_data() now there's no one
 199          */
 200
 201         tvb->real_data       = buf;
 202         tvb->length          = fd->cap_len;
 203         tvb->reported_length = fd->pkt_len > G_MAXINT ? G_MAXINT : fd->pkt_len;
 204         tvb->initialized     = TRUE;
 205
 206         /*
 207          * This is the top-level real tvbuff for this data source,
 208          * so its data source tvbuff is itself.
 209          */
 210         tvb->ds_tvb = tvb;
 211
 212         frame_tvb = (struct tvb_frame *) tvb;
 213
 214         /* XXX, wtap_can_seek() */
 215         if (cfile.wth && cfile.wth->random_fh
 216 #ifdef WANT_PACKET_EDITOR
 217                 && fd->file_off != -1 /* generic clone for modified packets */
 218 #endif
 219         ) {
 220                 frame_tvb->wth = cfile.wth;
 221                 frame_tvb->file_off = fd->file_off;
 222                 frame_tvb->offset = 0;
 223         } else
 224                 frame_tvb->wth = NULL;
 225
 226         frame_tvb->buf = NULL;
 227
 228         return tvb;
 229 }
 230
 231 tvbuff_t *
 232 frame_tvbuff_new_buffer(const frame_data *fd, Buffer *buf)
 233 {
 234         return frame_tvbuff_new(fd, buffer_start_ptr(buf));
 235 }
 236
 237 static tvbuff_t *
 238 frame_clone(tvbuff_t *tvb, guint abs_offset, guint abs_length)
 239 {
 240         struct tvb_frame *frame_tvb = (struct tvb_frame *) tvb;
 241
 242         tvbuff_t *cloned_tvb;
 243         struct tvb_frame *cloned_frame_tvb;
 244
 245         /* file not seekable */
 246         if (!frame_tvb->wth)
 247                 return NULL;
 248
 249         abs_offset += frame_tvb->offset;
 250
 251         cloned_tvb = tvb_new(&tvb_frame_ops);
 252
 253         /* data will be read when needed */
 254         cloned_tvb->real_data       = NULL;
 255         cloned_tvb->length          = abs_length;
 256         cloned_tvb->reported_length = abs_length; /* XXX? */
 257         cloned_tvb->initialized     = TRUE;
 258
 259         /*
 260          * This is the top-level real tvbuff for this data source,
 261          * so its data source tvbuff is itself.
 262          */
 263         cloned_tvb->ds_tvb = cloned_tvb;
 264
 265         cloned_frame_tvb = (struct tvb_frame *) cloned_tvb;
 266         cloned_frame_tvb->wth = frame_tvb->wth;
 267         cloned_frame_tvb->file_off = frame_tvb->file_off;
 268         cloned_frame_tvb->offset = abs_offset;
 269         cloned_frame_tvb->buf = NULL;
 270
 271         return cloned_tvb;
 272 }