forked from osmocom/wireshark
![Guy Harris](/assets/img/avatar_default.png)
Use WTAP_MAX_PACKET_SIZE_STANDARD, set to 256KB, for everything except for D-Bus captures. Use WTAP_MAX_PACKET_SIZE_DBUS, set to 128MB, for them, because that's the largest possible D-Bus message size. See https://bugs.freedesktop.org/show_bug.cgi?id=100220 for an example of the problems caused by limiting the snapshot length to 256KB for D-Bus. Have a snapshot length of 0 in a capture_file structure mean "there is no snapshot length for the file"; we don't need the has_snap field in that case, a value of 0 mean "no, we don't have a snapshot length". In dumpcap, start out with a pipe buffer size of 2KB, and grow it as necessary. When checking for a too-big packet from a pipe, check against the appropriate maximum - 128MB for DLT_DBUS, 256KB for everything else. Change-Id: Ib2ce7a0cf37b971fbc0318024fd011e18add8b20 Reviewed-on: https://code.wireshark.org/review/21952 Petri-Dish: Guy Harris <guy@alum.mit.edu> Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org> Reviewed-by: Guy Harris <guy@alum.mit.edu>
241 lines
7 KiB
C
241 lines
7 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_STANDARD,
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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_STANDARD 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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* 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#include "config.h"
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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 <wsutil/buffer.h>
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#include "mime_file.h"
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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 guint8 png_magic[] = { 0x89, 'P', 'N', 'G', '\r', '\n', 0x1A, '\n' };
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static const guint8 gif87a_magic[] = { 'G', 'I', 'F', '8', '7', 'a'};
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static const guint8 gif89a_magic[] = { 'G', 'I', 'F', '8', '9', 'a'};
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static const guint8 elf_magic[] = { 0x7F, 'E', 'L', 'F'};
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static const guint8 btsnoop_magic[] = { 'b', 't', 's', 'n', 'o', 'o', 'p', 0};
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static const guint8 pcap_magic[] = { 0xA1, 0xB2, 0xC3, 0xD4 };
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static const guint8 pcap_swapped_magic[] = { 0xD4, 0xC3, 0xB2, 0xA1 };
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static const guint8 pcapng_premagic[] = { 0x0A, 0x0D, 0x0D, 0x0A };
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/* File does not start with it */
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static const guint8 pcapng_xmagic[] = { 0x1A, 0x2B, 0x3C, 0x4D };
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static const guint8 pcapng_swapped_xmagic[] = { 0x4D, 0x3C, 0x2B, 0x1A };
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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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{ png_magic, sizeof(png_magic) },
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{ gif87a_magic, sizeof(gif87a_magic) },
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{ gif89a_magic, sizeof(gif89a_magic) },
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{ elf_magic, sizeof(elf_magic) },
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{ btsnoop_magic, sizeof(btsnoop_magic) },
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{ pcap_magic, sizeof(pcap_magic) },
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{ pcap_swapped_magic, sizeof(pcap_swapped_magic) },
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{ pcapng_premagic, sizeof(pcapng_premagic) }
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};
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#define N_MAGIC_TYPES (sizeof(magic_files) / sizeof(magic_files[0]))
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/*
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* Impose a not-too-large limit on the maximum file size, to avoid eating
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* up 99% of the (address space, swap partition, disk space for swap/page
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* files); if we were to return smaller chunks and let the dissector do
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* reassembly, it would *still* have to allocate a buffer the size of
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* the file, so it's not as if we'd neve try to allocate a buffer the
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* size of the file.
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*/
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#define MAX_FILE_SIZE G_MAXINT
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static gboolean
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mime_read_file(wtap *wth, FILE_T fh, struct wtap_pkthdr *phdr,
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Buffer *buf, int *err, gchar **err_info)
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{
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gint64 file_size;
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int packet_size;
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if ((file_size = wtap_file_size(wth, err)) == -1)
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return FALSE;
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if (file_size > MAX_FILE_SIZE) {
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/*
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* Don't blow up trying to allocate space for an
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* immensely-large file.
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*/
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*err = WTAP_ERR_BAD_FILE;
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*err_info = g_strdup_printf("mime_file: File has %" G_GINT64_MODIFIER "d-byte packet, bigger than maximum of %u",
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file_size, MAX_FILE_SIZE);
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return FALSE;
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}
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packet_size = (int)file_size;
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phdr->rec_type = REC_TYPE_PACKET;
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phdr->presence_flags = 0; /* yes, we have no bananas^Wtime stamp */
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phdr->caplen = packet_size;
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phdr->len = packet_size;
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phdr->ts.secs = 0;
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phdr->ts.nsecs = 0;
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return wtap_read_packet_bytes(fh, buf, packet_size, err, err_info);
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}
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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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gint64 offset;
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*err = 0;
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offset = file_tell(wth->fh);
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/* there is only ever one packet */
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if (offset != 0)
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return FALSE;
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*data_offset = offset;
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return mime_read_file(wth, wth->fh, &wth->phdr, wth->frame_buffer, err, err_info);
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}
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static gboolean
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mime_seek_read(wtap *wth, gint64 seek_off, struct wtap_pkthdr *phdr, Buffer *buf, int *err, gchar **err_info)
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{
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/* there is only one packet */
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if (seek_off > 0) {
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*err = 0;
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return FALSE;
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}
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if (file_seek(wth->random_fh, seek_off, SEEK_SET, err) == -1)
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return FALSE;
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return mime_read_file(wth, wth->random_fh, phdr, buf, err, err_info);
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}
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wtap_open_return_val
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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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gboolean found_file;
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/* guint file_ok; */
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guint i;
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guint read_bytes = 12;
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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 = (guint)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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*err = file_error(wth->fh, err_info);
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return WTAP_OPEN_ERROR;
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}
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if (bytes_read == 0)
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return WTAP_OPEN_NOT_MINE;
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found_file = FALSE;
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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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if (magic_files[i].magic == pcapng_premagic) {
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if (memcmp(magic_buf + 8, pcapng_xmagic, sizeof(pcapng_xmagic)) &&
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memcmp(magic_buf + 8, pcapng_swapped_xmagic, sizeof(pcapng_swapped_xmagic)))
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continue;
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}
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found_file = TRUE;
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} else
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return WTAP_OPEN_NOT_MINE; /* 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 WTAP_OPEN_NOT_MINE;
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if (file_seek(wth->fh, 0, SEEK_SET, err) == -1)
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return WTAP_OPEN_ERROR;
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wth->file_type_subtype = WTAP_FILE_TYPE_SUBTYPE_MIME;
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wth->file_encap = WTAP_ENCAP_MIME;
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wth->file_tsprec = WTAP_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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return WTAP_OPEN_MINE;
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}
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/*
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* Editor modelines - http://www.wireshark.org/tools/modelines.html
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*
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* Local variables:
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* c-basic-offset: 8
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* tab-width: 8
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* indent-tabs-mode: t
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* End:
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*
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* vi: set shiftwidth=8 tabstop=8 noexpandtab:
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* :indentSize=8:tabSize=8:noTabs=false:
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*/
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