![Guy Harris](/assets/img/avatar_default.png)
Otherwise, if you link with both libwiretap and libfiletap, it's anybody's guess which one you get. That means you're wasting memory with two copies of its routines if they're identical, and means surprising behavior if they're not (which showed up when I was debugging a double-free crash - fixing libwiretap's buffer_free() didn't fix the problem, because Wireshark happened to be calling libfiletap' unfixed buffer_free()). There's nothing *tap-specific about Buffers, anyway, so it really belongs in wsutil. Change-Id: I91537e46917e91277981f8f3365a2c0873152870 Reviewed-on: https://code.wireshark.org/review/3066 Reviewed-by: Guy Harris <guy@alum.mit.edu>
214 lines
5.8 KiB
C
214 lines
5.8 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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* 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 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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};
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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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* For now, go for 16MB.
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*/
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#define MAX_FILE_SIZE (16*1024*1024)
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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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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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gboolean found_file;
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/* guint file_ok; */
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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 = (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 -1;
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}
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if (bytes_read == 0)
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return 0;
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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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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_subtype = WTAP_FILE_TYPE_SUBTYPE_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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return 1;
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}
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