Listening on IPv6 any ([::]) fails because of SRTO_BINDTODEVICE

[jeandube]

listening on IPv6 any ([::]) no longer work with commit 4aa6fbb

11:23:39.842698 mxptool: setUDPSockOpt(channel.cpp:264): /App:Rx*E:SRT.c: SRTO_BINDTODEVICE can only be set with AF_INET connections
Application is not setting SRTO_BINDTODEVICE:
Breakpoint 1, CChannel::setUDPSockOpt (this=0x7fffe8008020) at /home/jdube/sandbox/makito2_project/components/vendors/haisrt/srt.git/srtcore/channel.cpp:264 264 LOGC(mglog.Error, log << "SRTO_BINDTODEVICE can only be set with AF_INET connections"); (gdb) bt #0 CChannel::setUDPSockOpt (this=0x7fffe8008020) at /home/jdube/sandbox/makito2_project/components/vendors/haisrt/srt.git/srtcore/channel.cpp:264 #1 0x000000000046f7f3 in CChannel::open (this=0x7fffe8008020, addr=...) at /home/jdube/sandbox/makito2_project/components/vendors/haisrt/srt.git/srtcore/channel.cpp:128 #2 0x000000000045b9f8 in CUDTUnited::updateMux (this=0x707600, s=0x7fffe8000d90, addr=..., udpsock=<optimized out>) at /home/jdube/sandbox/makito2_project/components/vendors/haisrt/srt.git/srtcore/api.cpp:2624 #3 0x000000000045cb09 in CUDTUnited::bind (this=0x707600, s=0x7fffe8000d90, name=...) at /home/jdube/sandbox/makito2_project/components/vendors/haisrt/srt.git/srtcore/api.cpp:864 #4 0x000000000045ccbd in CUDT::bind (u=<optimized out>, name=<optimized out>, namelen=<optimized out>) at /home/jdube/sandbox/makito2_project/components/vendors/haisrt/srt.git/srtcore/api.cpp:3013 #5 0x00000000004399a9 in srtconn_Open (srtc=0x718cd0, newsa=0x7175a0, newsalen=28, flags=0) at ../../libraries/naga/mxpmod_lib/srtc_mod.c:1842 #6 0x000000000043b2bc in SrtConn_Open (mxpc=0x718cd0, newsa=0x7175a0, newsalen=28, flags=0) at ../../libraries/naga/mxpmod_lib/srtc_mod.c:2093 #7 0x0000000000408772 in srtApp_LoopbackCx (loopcx=0x716870) at mxptool.c:376 #8 0x0000000000408d4c in srtApp_TxData (ref=0x716870, rxmsg=0x7fffe8000990) at mxptool.c:489 #9 0x000000000040953b in srtApp_RxProc (ref=0x715960, rxmsg=0x7fffe8000990) at mxptool.c:683 #10 0x0000000000409ab9 in srtApp_RxLoop (cx=0x715960) at mxptool.c:877 #11 0x000000000040b42b in srtApp_CxLoop (cx=0x715960, ai=0x7166c0, openf=0) at mxptool.c:1536 #12 0x000000000040b84b in srtApp_CxThread (s=0x715960) at mxptool.c:1595 #13 0x00007ffff74e9e9a in start_thread () from /lib/x86_64-linux-gnu/libpthread.so.0 #14 0x00007ffff6afd2ed in clone () from /lib/x86_64-linux-gnu/libc.so.6 #15 0x0000000000000000 in ?? ()

[jeandube]

Revisiting the fix to this problem: one line of this problem description was ignored:
Application is not setting SRTO_BINDTODEVICE

#ifdef SRT_ENABLE_BINDTODEVICE
      if (!m_BindToDevice.empty())
      {
          if (m_BindAddr.family() != AF_INET)
          {

The fix was to add the AF_INET line but m_BindToDevice should be empty. this CChannel member is not initialized..

[jeandube]

Or the default std::string constructor initialized it. Meanwhile my use case should not enter that if{} branch.

[ethouris]

Excuse me, but I don't understand the problem. Yes, m_BindToDevice should be empty, as default-initialized. This now belongs to a bigger object of CSrtMuxerConfig type, which is as itself put into the multiplexer, and it's also a part of CSrtConfig, which's object is in the socket. This "multiplexer part" of the object is simply assigned from the socket when creating a multiplexer.

Am I getting it right, you have a case when the app didn't set this value but it wasn't an empty string?

[jeandube]

Yes, application is not setting this value. I remember this problem I reported and that it was fixed but I just bumped on the fix while investigating the SRTO_BINDTODEVICE implementation. I will gdb to confirm.

[ethouris]

What is interesting, especially for the fields that should keep a string there's a type that allows to keep them as a fixed size character array. The m_BindToDevice is an exception.

[jeandube]

I retrieved the original code causing this problem (commit 4aa6fbb) and m_BindAddr.family != AF_INET generated an exception outside the !m_BindToDevice.empty() condition causing any IPv6 address binding to fail. I reopened issue while not understanding the fix. Closing issue.

#ifdef SRT_ENABLE_BINDTODEVICE
      if (m_BindAddr.family() != AF_INET)
      {
          LOGC(mglog.Error, log << "SRTO_BINDTODEVICE can only be set with AF_INET connections");
          throw CUDTException(MJ_NOTSUP, MN_INVAL, 0);
      }

      if (!m_BindToDevice.empty())
      {
          if (0 != ::setsockopt(m_iSocket, SOL_SOCKET, SO_BINDTODEVICE, m_BindToDevice.c_str(), m_BindToDevice.size()))
          {
              char buf[255];
              const char* err = SysStrError(NET_ERROR, buf, 255);
              LOGC(mglog.Error, log << "setsockopt(SRTO_BINDTODEVICE): " << err);
              throw CUDTException(MJ_SETUP, MN_NORES, NET_ERROR);
          }
      }
#endif