/**
  * This file is part of FFmpeg.
  *
  * FFmpeg is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
  * FFmpeg 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
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
  * License along with FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
 #include "encryption_info.h"
 #include "mem.h"
 #include "intreadwrite.h"
 
 #define FF_ENCRYPTION_INFO_EXTRA 24
 
 // The format of the AVEncryptionInfo side data:
 // u32be scheme
 // u32be crypt_byte_block
 // u32be skip_byte_block
 // u32be key_id_size
 // u32be iv_size
 // u32be subsample_count
 // u8[key_id_size] key_id
 // u8[iv_size] iv
 // {
 //   u32be bytes_of_clear_data
 //   u32be bytes_of_protected_data
 // }[subsample_count]
 
 AVEncryptionInfo *av_encryption_info_alloc(uint32_t subsample_count, uint32_t key_id_size, uint32_t iv_size)
 {
     AVEncryptionInfo *info;
 
     info = av_mallocz(sizeof(*info));
     if (!info)
         return NULL;
 
     info->key_id = av_mallocz(key_id_size);
     info->key_id_size = key_id_size;
     info->iv = av_mallocz(iv_size);
     info->iv_size = iv_size;
     info->subsamples = av_mallocz_array(subsample_count, sizeof(*info->subsamples));
     info->subsample_count = subsample_count;
 
     // Allow info->subsamples to be NULL if there are no subsamples.
     if (!info->key_id || !info->iv || (!info->subsamples && subsample_count)) {
         av_encryption_info_free(info);
         return NULL;
     }
 
     return info;
 }
 
 AVEncryptionInfo *av_encryption_info_clone(const AVEncryptionInfo *info)
 {
     AVEncryptionInfo *ret;
 
     ret = av_encryption_info_alloc(info->subsample_count, info->key_id_size, info->iv_size);
     if (!ret)
         return NULL;
 
     ret->scheme = info->scheme;
     ret->crypt_byte_block = info->crypt_byte_block;
     ret->skip_byte_block = info->skip_byte_block;
     memcpy(ret->iv, info->iv, info->iv_size);
     memcpy(ret->key_id, info->key_id, info->key_id_size);
     memcpy(ret->subsamples, info->subsamples, sizeof(*info->subsamples) * info->subsample_count);
     return ret;
 }
 
 void av_encryption_info_free(AVEncryptionInfo *info)
 {
     if (info) {
         av_free(info->key_id);
         av_free(info->iv);
         av_free(info->subsamples);
         av_free(info);
     }
 }
 
 AVEncryptionInfo *av_encryption_info_get_side_data(const uint8_t* buffer, size_t size)
 {
     AVEncryptionInfo *info;
     uint64_t key_id_size, iv_size, subsample_count, i;
 
     if (!buffer || size < FF_ENCRYPTION_INFO_EXTRA)
         return NULL;
 
     key_id_size = AV_RB32(buffer + 12);
     iv_size = AV_RB32(buffer + 16);
     subsample_count = AV_RB32(buffer + 20);
 
     if (size < FF_ENCRYPTION_INFO_EXTRA + key_id_size + iv_size + subsample_count * 8)
         return NULL;
 
     info = av_encryption_info_alloc(subsample_count, key_id_size, iv_size);
     if (!info)
         return NULL;
 
     info->scheme = AV_RB32(buffer);
     info->crypt_byte_block = AV_RB32(buffer + 4);
     info->skip_byte_block = AV_RB32(buffer + 8);
     memcpy(info->key_id, buffer + 24, key_id_size);
     memcpy(info->iv, buffer + key_id_size + 24, iv_size);
 
     buffer += key_id_size + iv_size + 24;
     for (i = 0; i < subsample_count; i++) {
         info->subsamples[i].bytes_of_clear_data = AV_RB32(buffer);
         info->subsamples[i].bytes_of_protected_data = AV_RB32(buffer + 4);
         buffer += 8;
     }
 
     return info;
 }
 
 uint8_t *av_encryption_info_add_side_data(const AVEncryptionInfo *info, size_t *size)
 {
     uint8_t *buffer, *cur_buffer;
     uint32_t i;
 
     if (UINT32_MAX - FF_ENCRYPTION_INFO_EXTRA < info->key_id_size ||
         UINT32_MAX - FF_ENCRYPTION_INFO_EXTRA - info->key_id_size < info->iv_size ||
         (UINT32_MAX - FF_ENCRYPTION_INFO_EXTRA - info->key_id_size - info->iv_size) / 8 < info->subsample_count) {
         return NULL;
     }
 
     *size = FF_ENCRYPTION_INFO_EXTRA + info->key_id_size + info->iv_size +
             (info->subsample_count * 8);
     cur_buffer = buffer = av_malloc(*size);
     if (!buffer)
         return NULL;
 
     AV_WB32(cur_buffer,      info->scheme);
     AV_WB32(cur_buffer +  4, info->crypt_byte_block);
     AV_WB32(cur_buffer +  8, info->skip_byte_block);
     AV_WB32(cur_buffer + 12, info->key_id_size);
     AV_WB32(cur_buffer + 16, info->iv_size);
     AV_WB32(cur_buffer + 20, info->subsample_count);
     cur_buffer += 24;
     memcpy(cur_buffer, info->key_id, info->key_id_size);
     cur_buffer += info->key_id_size;
     memcpy(cur_buffer, info->iv, info->iv_size);
     cur_buffer += info->iv_size;
     for (i = 0; i < info->subsample_count; i++) {
         AV_WB32(cur_buffer, info->subsamples[i].bytes_of_clear_data);
         AV_WB32(cur_buffer + 4, info->subsamples[i].bytes_of_protected_data);
         cur_buffer += 8;
     }
 
     return buffer;
 }
 
 // The format of the AVEncryptionInitInfo side data:

 // u32be init_info_count
 // {
 //   u32be system_id_size
 //   u32be num_key_ids
 //   u32be key_id_size
 //   u32be data_size
 //   u8[system_id_size] system_id
 //   u8[key_id_size][num_key_id] key_ids
 //   u8[data_size] data
 // }[init_info_count]

 
 #define FF_ENCRYPTION_INIT_INFO_EXTRA 16
 
 AVEncryptionInitInfo *av_encryption_init_info_alloc(
     uint32_t system_id_size, uint32_t num_key_ids, uint32_t key_id_size, uint32_t data_size)
 {
     AVEncryptionInitInfo *info;
     uint32_t i;
 
     info = av_mallocz(sizeof(*info));
     if (!info)
         return NULL;
 
     info->system_id = av_mallocz(system_id_size);
     info->system_id_size = system_id_size;
     info->key_ids = key_id_size ? av_mallocz_array(num_key_ids, sizeof(*info->key_ids)) : NULL;
     info->num_key_ids = num_key_ids;
     info->key_id_size = key_id_size;
     info->data = av_mallocz(data_size);
     info->data_size = data_size;
 
     // Allow pointers to be NULL if the size is 0.
     if ((!info->system_id && system_id_size) || (!info->data && data_size) ||
         (!info->key_ids && num_key_ids && key_id_size)) {
         av_encryption_init_info_free(info);
         return NULL;
     }
 
     if (key_id_size) {
         for (i = 0; i < num_key_ids; i++) {
             info->key_ids[i] = av_mallocz(key_id_size);
             if (!info->key_ids[i]) {
                 av_encryption_init_info_free(info);
                 return NULL;
             }
         }
     }
 
     return info;
 }
 
 void av_encryption_init_info_free(AVEncryptionInitInfo *info)
 {
     uint32_t i;
     if (info) {
         for (i = 0; i < info->num_key_ids; i++) {
             av_free(info->key_ids[i]);
         }

         av_encryption_init_info_free(info->next);

         av_free(info->system_id);
         av_free(info->key_ids);
         av_free(info->data);
         av_free(info);
     }
 }
 
 AVEncryptionInitInfo *av_encryption_init_info_get_side_data(
     const uint8_t *side_data, size_t side_data_size)
 {

     // |ret| tracks the front of the list, |info| tracks the back.
     AVEncryptionInitInfo *ret = NULL, *info, *temp_info;
     uint64_t system_id_size, num_key_ids, key_id_size, data_size, i, j;
     uint64_t init_info_count;

     if (!side_data || side_data_size < 4)

         return NULL;
 

     init_info_count = AV_RB32(side_data);
     side_data += 4;
     side_data_size -= 4;
     for (i = 0; i < init_info_count; i++) {
         if (side_data_size < FF_ENCRYPTION_INIT_INFO_EXTRA) {
             av_encryption_init_info_free(ret);
             return NULL;
         }

         system_id_size = AV_RB32(side_data);
         num_key_ids = AV_RB32(side_data + 4);
         key_id_size = AV_RB32(side_data + 8);
         data_size = AV_RB32(side_data + 12);

         // UINT32_MAX + UINT32_MAX + UINT32_MAX * UINT32_MAX == UINT64_MAX
         if (side_data_size - FF_ENCRYPTION_INIT_INFO_EXTRA < system_id_size + data_size + num_key_ids * key_id_size) {
             av_encryption_init_info_free(ret);
             return NULL;
         }
         side_data += FF_ENCRYPTION_INIT_INFO_EXTRA;
         side_data_size -= FF_ENCRYPTION_INIT_INFO_EXTRA;
 
         temp_info = av_encryption_init_info_alloc(system_id_size, num_key_ids, key_id_size, data_size);
         if (!temp_info) {
             av_encryption_init_info_free(ret);
             return NULL;
         }
         if (i == 0) {
             info = ret = temp_info;
         } else {
             info->next = temp_info;
             info = temp_info;
         }

         memcpy(info->system_id, side_data, system_id_size);
         side_data += system_id_size;
         side_data_size -= system_id_size;
         for (j = 0; j < num_key_ids; j++) {
             memcpy(info->key_ids[j], side_data, key_id_size);
             side_data += key_id_size;
             side_data_size -= key_id_size;
         }
         memcpy(info->data, side_data, data_size);
         side_data += data_size;
         side_data_size -= data_size;

     }
 

     return ret;

 }
 
 uint8_t *av_encryption_init_info_add_side_data(const AVEncryptionInitInfo *info, size_t *side_data_size)
 {

     const AVEncryptionInitInfo *cur_info;

     uint8_t *buffer, *cur_buffer;

     uint32_t i, init_info_count;
     uint64_t temp_side_data_size;
 
     temp_side_data_size = 4;
     init_info_count = 0;
     for (cur_info = info; cur_info; cur_info = cur_info->next) {

         temp_side_data_size += (uint64_t)FF_ENCRYPTION_INIT_INFO_EXTRA + cur_info->system_id_size + cur_info->data_size;

         if (init_info_count == UINT32_MAX || temp_side_data_size > UINT32_MAX) {

             return NULL;

         }
         init_info_count++;
 

         if (cur_info->num_key_ids) {
             temp_side_data_size += (uint64_t)cur_info->num_key_ids * cur_info->key_id_size;

             if (temp_side_data_size > UINT32_MAX) {
                 return NULL;
             }
         }

     }

     *side_data_size = temp_side_data_size;

 
     cur_buffer = buffer = av_malloc(*side_data_size);
     if (!buffer)
         return NULL;
 

     AV_WB32(cur_buffer, init_info_count);
     cur_buffer += 4;
     for (cur_info = info; cur_info; cur_info = cur_info->next) {
         AV_WB32(cur_buffer,      cur_info->system_id_size);
         AV_WB32(cur_buffer +  4, cur_info->num_key_ids);
         AV_WB32(cur_buffer +  8, cur_info->key_id_size);
         AV_WB32(cur_buffer + 12, cur_info->data_size);
         cur_buffer += 16;
 
         memcpy(cur_buffer, cur_info->system_id, cur_info->system_id_size);
         cur_buffer += cur_info->system_id_size;
         for (i = 0; i < cur_info->num_key_ids; i++) {
             memcpy(cur_buffer, cur_info->key_ids[i], cur_info->key_id_size);
             cur_buffer += cur_info->key_id_size;
         }

         if (cur_info->data_size > 0) {
             memcpy(cur_buffer, cur_info->data, cur_info->data_size);
             cur_buffer += cur_info->data_size;
         }

     }
 
     return buffer;
 }