[FFmpeg-devel] [patch]MMS protocol over TCP
zhentan feng
spyfeng
Tue Mar 30 19:09:23 CEST 2010
Hi
On Tue, Mar 30, 2010 at 6:42 AM, Michael Niedermayer <michaelni at gmx.at>wrote:
> 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?
>
>
yes, you are right. Since it maybe a error happened when overwriting.
I will add some debug info and return error code directly.
> > + 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
>
>
overwriting wouldn't happen here, because we actually realloc the size we
will copy to.
>
> > + 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?
>
>
yes, it's the end of the loop.
we retrieve data less than 8 bytes, it must be an error.
so we can return it directly at 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
>
> what do you mean about this?
could you explain it more?
thanks
>
> [...]
> > +static int mms_open_cnx(URLContext *h, const char *url)
>
> why is this a seperate function?
>
> it make no sense for now, I just follow the type from http.c.
there is a function http_open_cnx() in http.c
>
> [...]
> > + 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
>
>
yes.
but if I use pctx instead of NULL, I should add param URLContext *h for
every function which call dprintf().
the added param will only be used for print out the log info.
Is it really necessary?
[...]
zhentan
--
Best wishes~
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