modules/demux/xiph.h

   1 /*****************************************************************************
   2  * xiph.h: Xiph helpers
   3  *****************************************************************************
   4  * Copyright (C) 2010 Laurent Aimar
   5  *
   6  * Authors: Laurent Aimar <fenrir _AT_ videolan _DOT_ org>
   7  *
   8  * This program is free software; you can redistribute it and/or modify it
   9  * under the terms of the GNU Lesser General Public License as published by
  10  * the Free Software Foundation; either version 2.1 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  16  * GNU Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public License
  19  * along with this program; if not, write to the Free Software Foundation,
  20  * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  21  *****************************************************************************/
  22
  23 #include <assert.h>
  24 #include <limits.h>
  25 #define XIPH_MAX_HEADER_COUNT (256)
  26
  27 /* Temp ffmpeg vorbis format */
  28 static inline bool xiph_IsLavcFormat(const void *extra, unsigned i_extra,
  29                                      vlc_fourcc_t i_codec)
  30 {
  31     switch(i_codec)
  32     {
  33         case VLC_CODEC_VORBIS:
  34             return i_extra >= 6 && GetWBE(extra) == 30;
  35         case VLC_CODEC_THEORA:
  36             return i_extra >= 6 && GetWBE(extra) == 42;
  37         default:
  38             return false;
  39     }
  40 }
  41
  42 static inline unsigned xiph_CountLavcHeaders(const void *p_extra, unsigned i_extra)
  43 {
  44     const uint8_t *p = (const uint8_t*) p_extra;
  45     const uint8_t *p_end = &p[i_extra];
  46     /* Check headers count */
  47     for (int i=0; i<3; i++)
  48     {
  49         if(p_end - p < 2)
  50             return 0;
  51         uint16_t i_size = GetWBE(p);
  52         if(&p[2U + i_size] > p_end)
  53             return 0;
  54         p += 2 + i_size;
  55     }
  56     return 3;
  57 }
  58
  59 static inline unsigned xiph_CountHeaders(const void *p_extra, unsigned i_extra)
  60 {
  61     const uint8_t *p = (const uint8_t*) p_extra;
  62     if (!i_extra)
  63         return 0;
  64     /* First byte is headers count */
  65     if(1U + *p > i_extra)
  66         return 0;
  67     return *p + 1;
  68 }
  69
  70 static inline unsigned xiph_CountUnknownHeaders(const void *p_extra, unsigned i_extra,
  71                                                 vlc_fourcc_t i_codec)
  72 {
  73     if (xiph_IsLavcFormat(p_extra, i_extra, i_codec))
  74         return xiph_CountLavcHeaders(p_extra, i_extra);
  75     else
  76         return xiph_CountHeaders(p_extra, i_extra);
  77 }
  78
  79 static inline int xiph_SplitLavcHeaders(unsigned packet_size[],
  80                                         const void *packet[], unsigned *packet_count,
  81                                         unsigned i_extra, const void *p_extra)
  82 {
  83     const uint8_t *current = (const uint8_t *)p_extra;
  84     const uint8_t *end = &current[i_extra];
  85     if (i_extra < 2)
  86         return VLC_EGENERIC;
  87     /* Parse the packet count and their sizes */
  88     const unsigned count = xiph_CountLavcHeaders(current, i_extra);
  89     if(count == 0)
  90         return VLC_EGENERIC;
  91     if (packet_count)
  92         *packet_count = count;
  93     /* count is trusted here (xiph_CountHeaders) */
  94     for (unsigned i=0; i < count; i++)
  95     {
  96         /* each payload is prefixed by word size */
  97         packet_size[i] = GetWBE(current);
  98         if(&current[2U + packet_size[i]] > end)
  99             return VLC_EGENERIC;
 100         packet[i] = current + 2;
 101         current += packet_size[i] + 2;
 102     }
 103     return VLC_SUCCESS;
 104 }
 105
 106 static inline int xiph_SplitHeaders(unsigned packet_size[],
 107                                     const void *packet[], unsigned *packet_count,
 108                                     unsigned i_extra, const void *p_extra)
 109 {
 110     const uint8_t *current = (const uint8_t *)p_extra;
 111     const uint8_t *end = &current[i_extra];
 112     if (i_extra < 1)
 113         return VLC_EGENERIC;
 114
 115     /* Parse the packet count and their sizes */
 116     const unsigned count = xiph_CountHeaders(current, i_extra);
 117     if(count == 0)
 118         return VLC_EGENERIC;
 119
 120     if (packet_count)
 121         *packet_count = count;
 122
 123     /* - 1 byte (N-1) packets
 124      * - N-1 variable length payload sizes
 125      * - N-1 payloads
 126      * - Nth packet (remaining)  */
 127
 128     /* skip count byte header */
 129     ++current;
 130     /* read sizes for N-1 packets */
 131     unsigned total_payload_minus_last = 0;
 132     for (unsigned i = 0; i < count - 1; i++)
 133     {
 134         packet_size[i] = 0;
 135         for (;;) {
 136             if (current >= end)
 137                 return VLC_EGENERIC;
 138             packet_size[i] += *current;
 139             if (*current++ != 255)
 140                 break;
 141         }
 142         if(UINT_MAX - total_payload_minus_last < packet_size[i])
 143             return VLC_EGENERIC;
 144         total_payload_minus_last += packet_size[i];
 145     }
 146     if(current + total_payload_minus_last > end)
 147         return VLC_EGENERIC;
 148     /* set pointers for N-1 packets */
 149     for (unsigned i = 0; i < count - 1; i++)
 150     {
 151         packet[i] = current;
 152         current += packet_size[i];
 153     }
 154     /* Last packet is remaining size */
 155     packet_size[count - 1] = end - current;
 156     packet[count - 1] = current;
 157
 158     return VLC_SUCCESS;
 159 }
 160
 161 static inline int xiph_PackHeaders(int *extra_size, void **extra,
 162                                    unsigned packet_size[],
 163                                    const void *const packet[],
 164                                    unsigned packet_count)
 165 {
 166     if (packet_count <= 0 || packet_count > XIPH_MAX_HEADER_COUNT)
 167         return VLC_EGENERIC;
 168
 169     /* Compute the size needed for the whole extra data */
 170     unsigned payload_size = 0;
 171     unsigned header_size = 1;
 172     for (unsigned i = 0; i < packet_count; i++) {
 173         payload_size += packet_size[i];
 174         if (i < packet_count - 1)
 175             header_size += 1 + packet_size[i] / 255;
 176     }
 177
 178     /* */
 179     *extra_size = header_size + payload_size;
 180     *extra = malloc(*extra_size);
 181     if (*extra == NULL)
 182         return VLC_ENOMEM;
 183
 184     /* Write the header */
 185     uint8_t *current = (uint8_t*)*extra;
 186     *current++ = packet_count - 1;
 187     for (unsigned i = 0; i < packet_count - 1; i++) {
 188         unsigned t = packet_size[i];
 189         for (;;) {
 190             if (t >= 255) {
 191                 *current++ = 255;
 192                 t -= 255;
 193             } else {
 194                 *current++ = t;
 195                 break;
 196             }
 197         }
 198     }
 199
 200     /* Copy the payloads */
 201     for (unsigned i = 0; i < packet_count; i++) {
 202         if (packet_size[i] > 0) {
 203             memcpy(current, packet[i], packet_size[i]);
 204             current += packet_size[i];
 205         }
 206     }
 207     assert(current == (uint8_t*)*extra + *extra_size);
 208     return VLC_SUCCESS;
 209 }
 210
 211 static inline int xiph_AppendHeaders(int *extra_size, void **extra,
 212                                      unsigned size, const void *data)
 213 {
 214     unsigned packet_size[XIPH_MAX_HEADER_COUNT];
 215     const void *packet[XIPH_MAX_HEADER_COUNT];
 216     unsigned count;
 217
 218     if (*extra_size > 0 && *extra) {
 219         if (xiph_SplitHeaders(packet_size, packet, &count, *extra_size, *extra))
 220             return VLC_EGENERIC;
 221     } else {
 222         count = 0;
 223     }
 224     if (count >= XIPH_MAX_HEADER_COUNT)
 225         return VLC_EGENERIC;
 226
 227     void *old = *extra;
 228
 229     packet_size[count] = size;
 230     packet[count]      = (void*)data;
 231     if (xiph_PackHeaders(extra_size, extra, packet_size,
 232                          packet, count + 1)) {
 233         *extra_size = 0;
 234         *extra      = NULL;
 235     }
 236
 237     free(old);
 238
 239     if (*extra_size <= 0)
 240         return VLC_EGENERIC;
 241     return VLC_SUCCESS;
 242 }