[FFmpeg-devel] TCP socket descriptor leak on listen and interrupt

[Alexander Drozdov]

Hi all!

We are found another descriptors leak :-)

If we try to listen on TCP port and ff_listen() fails on
interrupt callback, socket (bind) descriptor overwrites at the tcp_open()
and does not closed at all.

As a result, we can't rebind to the same port.

Minimal sample for issue (sorry for C++ in some places :-), also sample
code assumes that librtmp does not used - it does not allow to listen):
```
#include <iostream>
#include <unistd.h>

extern "C" {
  #ifndef __STDC_CONSTANT_MACROS
  #define __STDC_CONSTANT_MACROS
  #endif

  #include <libavcodec/avcodec.h>
  #include <libavformat/avformat.h>
  #include <libavfilter/avfilter.h>
  #include <libswscale/swscale.h>
  #include <libavdevice/avdevice.h>
  #include <libswresample/swresample.h>
  #include <libavutil/log.h>
}

int openInputInterruptCallBack(void *ctx)
{
    // I know, stupid code :-) in real code more complex logic here
    return 1;
}

int main(int argc, char **argv) {
    std::cout << "Hello, world!" << std::endl;

    avdevice_register_all();
    avcodec_register_all();
    avfilter_register_all();
    av_register_all();
    avformat_network_init();

    AVFormatContext *mpFormatCtx = avformat_alloc_context();
    mpFormatCtx->interrupt_callback.callback = &openInputInterruptCallBack;
    mpFormatCtx->interrupt_callback.opaque   = mpFormatCtx;

    AVDictionary * dict = nullptr;
    av_dict_set_int(&dict, "rtmp_listen", 1, 0);
    av_dict_set_int(&dict, "timeout", -1, 0);
    av_dict_set(&dict, "rtmp_live", "live", 0);
    char* inputFileName = "rtmp://0.0.0.0:1936/live/mystream";
    AVInputFormat *pInAvFormat = av_find_input_format(inputFileName);

    int err = avformat_open_input(&mpFormatCtx, inputFileName, pInAvFormat,
&dict);
    // avformat_open_input() fails here but bind socket descriptor still
open.
    // we can check it via `ls -l /proc/PID/fd`

    if(err != 0)  {
        char errMsg[100];
        av_strerror(err, errMsg, 100);
        std::cout << "Couldn't open input source: " << inputFileName <<",
err : " << errMsg << std::endl;
        avformat_network_deinit();

        for (;;)
            sleep(1);

        return -1;
    } else {
        avformat_close_input(&mpFormatCtx);
        avformat_network_deinit();
    }

    return 0;
}
```

Fix is attached to the letter.

-- 
WBR, Alexander Drozdov
http://htrd.su
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