/* mpeg.c * * MPEG file format decoder for the Wiretap library. * Written by Shaun Jackman * Copyright 2007 Shaun Jackman * * Wiretap Library * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version 2 * of the License, or (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. */ #include "config.h" #ifdef HAVE_SYS_TYPES_H #include #endif #ifdef HAVE_UNISTD_H #include #endif #include "mpeg.h" #include "wsutil/mpeg-audio.h" #include "wtap-int.h" #include #include "file_wrappers.h" #include #include #include #include #define PES_PREFIX 1 #define PES_VALID(n) (((n) >> 8 & 0xffffff) == PES_PREFIX) typedef struct { nstime_t now; time_t t0; } mpeg_t; static int mpeg_resync(FILE_T fh, int *err) { gint64 offset = file_tell(fh); int count = 0; int byte = file_getc(fh); while (byte != EOF) { if (byte == 0xff && count > 0) { byte = file_getc(fh); if (byte != EOF && (byte & 0xe0) == 0xe0) break; } else byte = file_getc(fh); count++; } if (file_seek(fh, offset, SEEK_SET, err) == -1) return 0; return count; } #define SCRHZ 27000000 static gboolean mpeg_read_packet(wtap *wth, FILE_T fh, struct wtap_pkthdr *phdr, Buffer *buf, gboolean is_random, int *err, gchar **err_info) { mpeg_t *mpeg = (mpeg_t *)wth->priv; guint32 n; unsigned int packet_size; nstime_t ts = mpeg->now; /* * All packets have at least 4 bytes in them. Read the first * 4 bytes and determine whether it's a PES packet or not * based on that. * * XXX - can an MPEG file contain a mixture of PES and non-PES * packets? If not, can we determine whether the packets will * be PES packets or not based on the magic number (i.e., if the * file begins with 0x00 0x00 0x01, it contains PES packets, * otherwise it doesn't)? */ if (!wtap_read_bytes_or_eof(fh, &n, sizeof n, err, err_info)) return FALSE; if (file_seek(fh, -(gint64)(sizeof n), SEEK_CUR, err) == -1) return FALSE; n = g_ntohl(n); if (PES_VALID(n)) { gint64 offset = file_tell(fh); guint8 stream; if (!file_skip(fh, 3, err)) return FALSE; if (!wtap_read_bytes(fh, &stream, sizeof stream, err, err_info)) return FALSE; if (stream == 0xba) { guint32 pack1; guint32 pack0; guint64 pack; guint8 stuffing; if (!wtap_read_bytes(fh, &pack1, sizeof pack1, err, err_info)) return FALSE; if (!wtap_read_bytes(fh, &pack0, sizeof pack0, err, err_info)) return FALSE; pack = (guint64)g_ntohl(pack1) << 32 | g_ntohl(pack0); switch (pack >> 62) { case 1: if (!file_skip(fh, 1, err)) return FALSE; if (!wtap_read_bytes(fh, &stuffing, sizeof stuffing, err, err_info)) return FALSE; stuffing &= 0x07; packet_size = 14 + stuffing; if (!is_random) { guint64 bytes = pack >> 16; guint64 ts_val = (bytes >> 43 & 0x0007) << 30 | (bytes >> 27 & 0x7fff) << 15 | (bytes >> 11 & 0x7fff) << 0; guint ext = (guint)((bytes >> 1) & 0x1ff); guint64 cr = 300 * ts_val + ext; guint rem = (guint)(cr % SCRHZ); mpeg->now.secs = mpeg->t0 + (time_t)(cr / SCRHZ); mpeg->now.nsecs = (int)(G_GINT64_CONSTANT(1000000000) * rem / SCRHZ); } ts = mpeg->now; break; default: packet_size = 12; } } else { guint16 length; if (!wtap_read_bytes(fh, &length, sizeof length, err, err_info)) return FALSE; length = g_ntohs(length); packet_size = 6 + length; } if (file_seek(fh, offset, SEEK_SET, err) == -1) return FALSE; } else { struct mpa mpa; MPA_UNMARSHAL(&mpa, n); if (MPA_VALID(&mpa)) { packet_size = MPA_BYTES(&mpa); if (!is_random) { mpeg->now.nsecs += MPA_DURATION_NS(&mpa); if (mpeg->now.nsecs >= 1000000000) { mpeg->now.secs++; mpeg->now.nsecs -= 1000000000; } } } else { packet_size = mpeg_resync(fh, err); if (packet_size == 0) return FALSE; } } if (!wtap_read_packet_bytes(fh, buf, packet_size, err, err_info)) return FALSE; phdr->rec_type = REC_TYPE_PACKET; /* XXX - relative, not absolute, time stamps */ if (!is_random) { phdr->presence_flags = WTAP_HAS_TS; phdr->ts = ts; } phdr->caplen = packet_size; phdr->len = packet_size; return TRUE; } static gboolean mpeg_read(wtap *wth, int *err, gchar **err_info, gint64 *data_offset) { *data_offset = file_tell(wth->fh); return mpeg_read_packet(wth, wth->fh, &wth->phdr, wth->frame_buffer, FALSE, err, err_info); } static gboolean mpeg_seek_read(wtap *wth, gint64 seek_off, struct wtap_pkthdr *phdr, Buffer *buf, int *err, gchar **err_info) { if (file_seek(wth->random_fh, seek_off, SEEK_SET, err) == -1) return FALSE; if (!mpeg_read_packet(wth, wth->random_fh, phdr, buf, TRUE, err, err_info)) { if (*err == 0) *err = WTAP_ERR_SHORT_READ; return FALSE; } return TRUE; } struct _mpeg_magic { size_t len; const gchar* match; } magic[] = { { 3, "TAG" }, /* ID3v1 */ { 3, "ID3" }, /* ID3v2 */ { 3, "\0\0\1" }, /* MPEG PES */ { 2, "\xff\xfb" }, /* MP3, taken from http://en.wikipedia.org/wiki/MP3#File_structure */ { 0, NULL } }; wtap_open_return_val mpeg_open(wtap *wth, int *err, gchar **err_info) { char magic_buf[16]; struct _mpeg_magic* m; mpeg_t *mpeg; if (!wtap_read_bytes(wth->fh, magic_buf, sizeof magic_buf, err, err_info)) { if (*err != WTAP_ERR_SHORT_READ) return WTAP_OPEN_ERROR; return WTAP_OPEN_NOT_MINE; } for (m=magic; m->match; m++) { if (memcmp(magic_buf, m->match, m->len) == 0) goto good_magic; } return WTAP_OPEN_NOT_MINE; good_magic: /* This appears to be a file with MPEG data. */ if (file_seek(wth->fh, 0, SEEK_SET, err) == -1) return WTAP_OPEN_ERROR; wth->file_type_subtype = WTAP_FILE_TYPE_SUBTYPE_MPEG; wth->file_encap = WTAP_ENCAP_MPEG; wth->file_tsprec = WTAP_TSPREC_NSEC; wth->subtype_read = mpeg_read; wth->subtype_seek_read = mpeg_seek_read; wth->snapshot_length = 0; mpeg = (mpeg_t *)g_malloc(sizeof(mpeg_t)); wth->priv = (void *)mpeg; mpeg->now.secs = 0; mpeg->now.nsecs = 0; mpeg->t0 = mpeg->now.secs; return WTAP_OPEN_MINE; } /* * Editor modelines - http://www.wireshark.org/tools/modelines.html * * Local variables: * c-basic-offset: 8 * tab-width: 8 * indent-tabs-mode: t * End: * * vi: set shiftwidth=8 tabstop=8 noexpandtab: * :indentSize=8:tabSize=8:noTabs=false: */