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rtmpproto: Add function to read a number response

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Packets that contain a number as a result to a rtmp function call are
structured the same way (String, Number, Null, Number). This new method
also includes more bounds checks to better handle packets that are not
structured as expected.

Signed-off-by: Martin Storsjö <martin@martin.st>
This commit is contained in:
Uwe L. Korn 2014-10-14 17:16:20 +02:00 committed by Martin Storsjö
parent 47e3e1097e
commit 324b23dde1
1 changed files with 42 additions and 3 deletions
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45
libavformat/rtmpproto.c
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@ -1953,6 +1953,45 @@ static int send_invoke_response(URLContext *s, RTMPPacket *pkt)
return ret;
}
/**
* Read the AMF_NUMBER response ("_result") to a function call
* (e.g. createStream()). This response should be made up of the AMF_STRING
* "result", a NULL object and then the response encoded as AMF_NUMBER. On a
* successful response, we will return set the value to number (otherwise number
* will not be changed).
*
* @return 0 if reading the value succeeds, negative value otherwiss
*/
static int read_number_result(RTMPPacket *pkt, double *number)
{
// We only need to fit "_result" in this.
uint8_t strbuffer[8];
int stringlen;
double numbuffer;
GetByteContext gbc;
bytestream2_init(&gbc, pkt->data, pkt->size);
// Value 1/4: "_result" as AMF_STRING
if (ff_amf_read_string(&gbc, strbuffer, sizeof(strbuffer), &stringlen))
return AVERROR_INVALIDDATA;
if (strcmp(strbuffer, "_result"))
return AVERROR_INVALIDDATA;
// Value 2/4: The callee reference number
if (ff_amf_read_number(&gbc, &numbuffer))
return AVERROR_INVALIDDATA;
// Value 3/4: Null
if (ff_amf_read_null(&gbc))
return AVERROR_INVALIDDATA;
// Value 4/4: The resonse as AMF_NUMBER
if (ff_amf_read_number(&gbc, &numbuffer))
return AVERROR_INVALIDDATA;
else
*number = numbuffer;
return 0;
}
static int handle_invoke_result(URLContext *s, RTMPPacket *pkt)
{
RTMPContext *rt = s->priv_data;
@ -1994,11 +2033,11 @@ static int handle_invoke_result(URLContext *s, RTMPPacket *pkt)
}
}
} else if (!strcmp(tracked_method, "createStream")) {
//extract a number from the result
if (pkt->data[10] || pkt->data[19] != 5 || pkt->data[20]) {
double stream_id;
if (read_number_result(pkt, &stream_id)) {
av_log(s, AV_LOG_WARNING, "Unexpected reply on connect()\n");
} else {
rt->stream_id = av_int2double(AV_RB64(pkt->data + 21));
rt->stream_id = stream_id;
}
if (!rt->is_input) {