[FFmpeg-devel] [patch]MMS protocol over TCP
Michael Niedermayer
michaelni
Tue Mar 30 00:42:01 CEST 2010
On Sun, Mar 28, 2010 at 12:13:24AM +0800, zhentan feng wrote:
[...]
> +
> +/** Read incoming MMST media, header or command packet. */
> +static MMSSCPacketType get_tcp_server_response(MMSContext *mms)
> +{
> + int read_result;
> + MMSSCPacketType packet_type= -1;
> + int done;
> +
> + do {
> + done= 1;
> + if((read_result= url_read_complete(mms->mms_hd, mms->incoming_buffer, 8))==8) {
> + // handle command packet.
> + if(AV_RL32(mms->incoming_buffer + 4)==0xb00bface) {
> + mms->incoming_flags= mms->incoming_buffer[3];
> + read_result= url_read_complete(mms->mms_hd, mms->incoming_buffer+8, 4);
> + if(read_result == 4) {
> + int length_remaining= AV_RL32(mms->incoming_buffer+8) + 4;
> +
> + dprintf(NULL, "Length remaining is %d\n", length_remaining);
> + // read the rest of the packet.
> + read_result = url_read_complete(mms->mms_hd, mms->incoming_buffer + 12,
> + length_remaining) ;
> + if (read_result == length_remaining) {
> + mms->incoming_buffer_length= length_remaining+12;
> + packet_type= AV_RL16(mms->incoming_buffer+36);
> +
> + } else {
> + dprintf(NULL, "3 read returned %d!\n", read_result);
> + }
> + } else {
> + dprintf(NULL, "2 read returned %d!\n", read_result);
> + }
> + } else {
> + int length_remaining;
> + int packet_id_type;
> + int tmp;
> +
> + assert(mms->pkt_buf_len==0);
> +
> + //** VERIFY LENGTH REMAINING HAS SPACE
> + // note we cache the first 8 bytes,
> + // then fill up the buffer with the others
> + tmp = AV_RL16(mms->incoming_buffer + 6);
> + length_remaining = (tmp - 8) & 0xffff;
> + mms->incoming_packet_seq = AV_RL32(mms->incoming_buffer);
> + packet_id_type = mms->incoming_buffer[4];
> + mms->incoming_flags = mms->incoming_buffer[5];
> + mms->pkt_buf_len = length_remaining;
> + mms->pkt_read_ptr = mms->incoming_buffer;
> +
> + read_result= url_read_complete(mms->mms_hd, mms->incoming_buffer, length_remaining);
is there any check for not overwriting the array bounds?
> + if(read_result != length_remaining) {
> + dprintf(NULL, "read_bytes result: %d asking for %d\n",
> + read_result, length_remaining);
> + break;
> + } else {
> + // if we successfully read everything.
> + if(packet_id_type == mms->header_packet_id) {
> + packet_type = SC_PKT_ASF_HEADER;
> + // Store the asf header
> + if(!mms->header_parsed) {
> + mms->asf_header = av_realloc(mms->asf_header,
> + mms->asf_header_size
> + + mms->pkt_buf_len);
missing check for realloc failure
also can mms->asf_header_size + mms->pkt_buf_len overflow? if so it
must be checked
> + memcpy(mms->asf_header + mms->asf_header_size,
> + mms->pkt_read_ptr,
> + mms->pkt_buf_len);
> + mms->asf_header_size += mms->pkt_buf_len;
> + }
> + } else if(packet_id_type == mms->packet_id) {
> + packet_type = SC_PKT_ASF_MEDIA;
> + } else {
> + dprintf(NULL, "packet id type %d is old.", packet_id_type);
> + done= 0;
> + }
> + }
> + }
> + } else {
> + if(read_result<0) {
> + dprintf(NULL, "Read error (or cancelled) returned %d!\n", read_result);
> + packet_type = SC_PKT_CANCEL;
> + } else {
> + dprintf(NULL, "Read result of zero?!\n");
> + packet_type = SC_PKT_NO_DATA;
> + }
> + done = 1;
can done be anything else than 1 here?
[...]
> +static int asf_header_parser(MMSContext *mms)
> +{
> + uint8_t *p = mms->asf_header, *end = mms->asf_header + mms->asf_header_size;
> + mms->stream_num = 0;
> +
> + if (mms->asf_header_size < sizeof(ff_asf_guid) * 2 + 22 ||
> + memcmp(p, ff_asf_header, sizeof(ff_asf_guid)))
> + return -1;
> +
> + p += sizeof(ff_asf_guid) + 14;
> + do {
> + uint64_t chunksize = AV_RL64(p + sizeof(ff_asf_guid));
> + if (!memcmp(p, ff_asf_file_header, sizeof(ff_asf_guid))) {
> + /* read packet size */
> + if (end - p > sizeof(ff_asf_guid) * 2 + 68) {
> + mms->asf_packet_len = AV_RL32(p + sizeof(ff_asf_guid) * 2 + 64);
> + }
> + } else if (!memcmp(p, ff_asf_stream_header, sizeof(ff_asf_guid))) {
> + mms->stream_num++;
shouldnt the number be limited somehow? at some place in the code
you write data for each stream into a fixed size buffer
[...]
> +static int mms_open_cnx(URLContext *h, const char *url)
why is this a seperate function?
[...]
> + mms = av_malloc(sizeof(MMSContext));
> + if (!mms)
> + return AVERROR(ENOMEM);
> + memset(mms, 0, sizeof(MMSContext));
av_mallocz()
[...]
> +/** Read ASF data through the protocol. */
> +static int mms_read(URLContext *h, uint8_t *buf, int size)
> +{
> + /* TODO: see tcp.c:tcp_read() about a possible timeout scheme */
> + MMSContext *mms = h->priv_data;
> + int result = 0;
> +
> + /* Since we read the header at open(), this shouldn't be possible */
> + assert(mms->header_parsed);
> +
> + if (mms->asf_header_read_pos >= mms->asf_header_size
> + && !mms->streaming_flag) {
> + dprintf(NULL, "mms_read() before play().\n");
> + clear_stream_buffers(mms);
> + result = send_stream_selection_request(mms);
> + if(result < 0)
> + return result;
> + if (get_tcp_server_response(mms) != SC_PKT_STREAM_ID_ACCEPTED) {
> + dprintf(NULL, "Can't get stream id accepted packet.\n");
> + return 0;
> + }
> +
> + // send media packet request
> + send_media_packet_request(mms);
> + if (get_tcp_server_response(mms) == SC_PKT_MEDIA_PKT_FOLLOWS) {
> + mms->streaming_flag = 1;
> + } else {
> + dprintf(NULL, "Canot get media follows packet from server.\n");
using NULL as context for dprintf() is not ideal
[...]
--
Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
Asymptotically faster algorithms should always be preferred if you have
asymptotical amounts of data
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