static vod_status_t
mp4_encrypt_write_encrypted(
mp4_encrypt_state_t* state,
u_char* cur_pos,
uint32_t write_size)
{
uint32_t cur_write_size;
size_t alloc_size;
u_char* write_end;
u_char* output;
vod_status_t rc;
write_end = cur_pos + write_size;
while (cur_pos < write_end)
{
rc = write_buffer_get_bytes(&state->write_buffer, MIN_ALLOC_SIZE, &alloc_size, &output);
if (rc != VOD_OK)
{
return rc;
}
cur_write_size = write_end - cur_pos;
cur_write_size = vod_min(cur_write_size, alloc_size);
rc = mp4_aes_ctr_process(&state->cipher, output, cur_pos, cur_write_size);
if (rc != VOD_OK)
{
return rc;
}
cur_pos += cur_write_size;
state->write_buffer.cur_pos += cur_write_size;
}
return VOD_OK;
}
static vod_status_t
mp4_decrypt_process(
mp4_decrypt_state_t* state,
size_t size)
{
u_char* dest = state->output_pos;
u_char* src = state->input_pos;
vod_status_t rc;
size_t cur_size;
while (size > 0)
{
if (state->clear_bytes <= 0 && state->encrypted_bytes <= 0)
{
// finished a subsample, read the next one
if (state->subsample_count <= 0)
{
vod_log_error(VOD_LOG_ERR, state->request_context->log, 0,
"mp4_decrypt_process: exhausted subsample bytes");
return VOD_BAD_DATA;
}
if (state->auxiliary_info_pos + sizeof(cenc_sample_auxiliary_data_subsample_t) > state->auxiliary_info_end)
{
vod_log_error(VOD_LOG_ERR, state->request_context->log, 0,
"mp4_decrypt_process: failed to get subsample info from auxiliary info");
return VOD_BAD_DATA;
}
read_be16(state->auxiliary_info_pos, state->clear_bytes);
read_be32(state->auxiliary_info_pos, state->encrypted_bytes);
state->subsample_count--;
}
if (state->clear_bytes > 0)
{
// copy clear bytes
cur_size = vod_min(state->clear_bytes, size);
dest = vod_copy(dest, src, cur_size);
src += cur_size;
size -= cur_size;
state->clear_bytes -= cur_size;
}
// decrypt encrypted bytes
cur_size = vod_min(state->encrypted_bytes, size);
rc = mp4_aes_ctr_process(&state->cipher, dest, src, cur_size);
if (rc != VOD_OK)
{
return rc;
}
dest += cur_size;
src += cur_size;
size -= cur_size;
state->encrypted_bytes -= cur_size;
}
state->output_pos = dest;
state->input_pos = src;
return VOD_OK;
}
