33bb54a945
which could use lseek() and were thus expensive due to system call overhead. To avoid making a system call for every packet on a sequential read, we maintained a data_offset field in the wtap structure for sequential reads. It's now a routine that just returns information from the FILE_T data structure, so it's cheap. Use it, rather than maintaining the data_offset field. Readers for some file formats need to maintain file offset themselves; have them do so in their private data structures. svn path=/trunk/; revision=42423
199 lines
4.9 KiB
C
199 lines
4.9 KiB
C
/* mime_file.c
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*
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* MIME file format decoder for the Wiretap library.
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*
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* This is for use with Wireshark dissectors that handle file
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* formats (e.g., because they handle a particular MIME media type).
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* It breaks the file into chunks of at most WTAP_MAX_PACKET_SIZE,
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* each of which is reported as a packet, so that files larger than
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* WTAP_MAX_PACKET_SIZE can be handled by reassembly.
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*
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* The "MIME file" dissector does the reassembly, and hands the result
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* off to heuristic dissectors to try to identify the file's contents.
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*
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* $Id$
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*
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* Wiretap Library
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*/
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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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#ifdef HAVE_SYS_TYPES_H
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#include <sys/types.h>
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#endif
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#ifdef HAVE_UNISTD_H
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#include <unistd.h>
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#endif
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#include <errno.h>
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#include <stdlib.h>
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#include <string.h>
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#include <time.h>
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#include "wtap-int.h"
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#include "file_wrappers.h"
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#include "buffer.h"
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#include "mime_file.h"
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typedef struct {
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gboolean last_packet;
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} mime_file_private_t;
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typedef struct {
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const guint8 *magic;
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guint magic_len;
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} mime_files_t;
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/*
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* Written by Marton Nemeth <nm127@freemail.hu>
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* Copyright 2009 Marton Nemeth
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* The JPEG and JFIF specification can be found at:
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*
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* http://www.jpeg.org/public/jfif.pdf
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* http://www.w3.org/Graphics/JPEG/itu-t81.pdf
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*/
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static const guint8 jpeg_jfif_magic[] = { 0xFF, 0xD8, /* SOF */
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0xFF /* start of the next marker */
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};
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/* <?xml */
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static const guint8 xml_magic[] = { '<', '?', 'x', 'm', 'l' };
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static const mime_files_t magic_files[] = {
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{ jpeg_jfif_magic, sizeof(jpeg_jfif_magic) },
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{ xml_magic, sizeof(xml_magic) }
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};
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#define N_MAGIC_TYPES (sizeof(magic_files) / sizeof(magic_files[0]))
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static gboolean
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mime_read(wtap *wth, int *err, gchar **err_info, gint64 *data_offset)
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{
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mime_file_private_t *priv = (mime_file_private_t *) wth->priv;
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char _buf[WTAP_MAX_PACKET_SIZE];
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guint8 *buf;
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int packet_size;
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if (priv->last_packet) {
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*err = file_error(wth->fh, err_info);
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return FALSE;
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}
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wth->phdr.presence_flags = 0;
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wth->phdr.ts.secs = 0;
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wth->phdr.ts.nsecs = 0;
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*data_offset = file_tell(wth->fh);
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/* try to read max WTAP_MAX_PACKET_SIZE bytes */
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packet_size = file_read(_buf, sizeof(_buf), wth->fh);
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if (packet_size <= 0) {
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priv->last_packet = TRUE;
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/* signal error for packet-mime-encap */
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if (packet_size < 0)
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wth->phdr.ts.nsecs = 1000000000;
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wth->phdr.caplen = 0;
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wth->phdr.len = 0;
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return TRUE;
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}
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/* copy to wth frame buffer */
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buffer_assure_space(wth->frame_buffer, packet_size);
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buf = buffer_start_ptr(wth->frame_buffer);
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memcpy(buf, _buf, packet_size);
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wth->phdr.caplen = packet_size;
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wth->phdr.len = packet_size;
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return TRUE;
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}
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static gboolean
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mime_seek_read(wtap *wth, gint64 seek_off, union wtap_pseudo_header *pseudo_header _U_, guint8 *pd, int length, int *err, gchar **err_info)
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{
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if (file_seek(wth->random_fh, seek_off, SEEK_SET, err) == -1) {
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*err_info = NULL;
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return FALSE;
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}
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wtap_file_read_expected_bytes(pd, length, wth->random_fh, err, err_info);
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*err = 0;
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*err_info = NULL;
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return TRUE;
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}
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int
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mime_file_open(wtap *wth, int *err, gchar **err_info)
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{
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char magic_buf[128]; /* increase buffer size when needed */
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int bytes_read;
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int ret;
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guint i;
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guint read_bytes = 0;
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for (i = 0; i < N_MAGIC_TYPES; i++)
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read_bytes = MAX(read_bytes, magic_files[i].magic_len);
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read_bytes = MIN(read_bytes, sizeof(magic_buf));
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bytes_read = file_read(magic_buf, read_bytes, wth->fh);
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if (bytes_read > 0) {
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gboolean found_file = FALSE;
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/* guint file_ok; */
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for (i = 0; i < N_MAGIC_TYPES; i++) {
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if ((guint) bytes_read >= magic_files[i].magic_len && !memcmp(magic_buf, magic_files[i].magic, MIN(magic_files[i].magic_len, (guint) bytes_read))) {
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if (!found_file) {
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found_file = TRUE;
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/* file_ok = i; */
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} else
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return 0; /* many files matched, bad file */
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}
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}
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if (!found_file)
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return 0;
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if (file_seek(wth->fh, 0, SEEK_SET, err) == -1)
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return -1;
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wth->file_type = WTAP_FILE_MIME;
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wth->file_encap = WTAP_ENCAP_MIME;
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wth->tsprecision = WTAP_FILE_TSPREC_SEC;
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wth->subtype_read = mime_read;
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wth->subtype_seek_read = mime_seek_read;
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wth->snapshot_length = 0;
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ret = 1;
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wth->priv = g_malloc0(sizeof(mime_file_private_t));
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} else {
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*err = file_error(wth->fh, err_info);
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ret = -1;
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}
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return ret;
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}
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