Fixed default binding for IPv6-target rendezvous. Updated documentation.

apps/transmitmedia.cpp

@@ -436,25 +436,28 @@ void SrtCommon::OpenRendezvous(string adapter, string host, int port)
     if ( stat == SRT_ERROR )
         Error("ConfigurePre");
 
+    sockaddr_any sa = CreateAddr(host, port);
+    if (sa.family() == AF_UNSPEC)
+    {
+        Error("OpenRendezvous: invalid target host specification: " + host);
+    }
+
     const int outport = m_outgoing_port ? m_outgoing_port : port;
 
-    sockaddr_any localsa = CreateAddr(adapter, outport);
-	sockaddr* plsa = localsa.get();
+    sockaddr_any localsa = CreateAddr(adapter, outport, sa.family());
 
     Verb() << "Binding a server on " << adapter << ":" << outport;
 
-    stat = srt_bind(m_sock, plsa, sizeof localsa);
+    stat = srt_bind(m_sock, localsa.get(), sizeof localsa);
     if ( stat == SRT_ERROR )
     {
         srt_close(m_sock);
         Error("srt_bind");
     }
 
-    sockaddr_any sa = CreateAddr(host, port);
-	sockaddr* psa = sa.get();
     Verb() << "Connecting to " << host << ":" << port;
 
-    stat = srt_connect(m_sock, psa, sizeof sa);
+    stat = srt_connect(m_sock, sa.get(), sizeof sa);
     if ( stat == SRT_ERROR )
     {
         srt_close(m_sock);

docs/srt-live-transmit.md

@@ -220,6 +220,53 @@ specified in the URI:
     -   The **adapter** parameter can be used to specify the adapter.
     -   The **port** parameter can be used to specify the local port to bind to.
 
+**IMPORTANT** information about IPv6.
+
+This application can also use an address specified as IPv6 with
+the following restrictions:
+
+1. The IPv6 address in the URI is specified in square brackets: e.g.
+`srt://[::1]:5000`.
+
+2. In listener mode, if you leave the host empty, the socket is bound to
+`INADDR_ANY` for IPv4 only. If you want to make it listen on IPv6, you need to
+specify the host as `::`.
+NOTE: Don't use square brackets syntax in the adapter specification, 
+as in this case only the host is expected.
+
+3. If you want to listen for connections from both IPv4 and IPv6, mind the
+`ipv6only` option. The default value for this option is system default (see
+system manual for `IPV6_V6ONLY` socket option); if unsure, you might want to
+enforce `ipv6only=0` in order to be able to accept both IPv4 and IPv6
+connections in the same listener.
+
+4. In rendezvous mode you may only interconnect both parties using IPv4, 
+or both using IPv6. Unlike listener mode, if you want to leave the socket
+default-bound (you don't specify `adapter`), the socket will be bound with the
+same IP version as the target address. If you do specify `adapter`,
+then both this address and the target address must be of the same family.
+
+Examples:
+
+* `srt://:5000` defines listener mode with IPv4.
+
+* `srt://[::]:5000` defines caller mode (!) with IPv6.
+
+* `srt://[::]:5000?mode=listener` defines listener mode with IPv6. If the
+* default value for `IPV6_V6ONLY` system socket option is 0, it will accept
+* also IPv4 connections.
+
+* `srt://192.168.0.5:5000?mode=rendezvous` will make a rendezvous connection
+* with local address `INADDR_ANY` (IPv4) and port 5000 to a destination with
+* port 5000.
+
+* `srt://[::1]:5000?mode=rendezvous&port=4000` will make a rendezvous
+* connection with local address `inaddr6_any` (IPv6) and port 4000 to a
+* destination with port 5000.
+
+* `srt://[::1]:5000?adapter=127.0.0.1&mode=rendezvous` - this URI is invalid
+* (different IP versions for binding and target address)
+
 Some parameters handled for SRT medium are specific, all others are socket options. The following parameters are handled special way by *srt-live-transmit*:
 
 - **mode**: enforce caller, listener or rendezvous mode

srtcore/api.cpp

@@ -1589,8 +1589,19 @@ int CUDTUnited::connectIn(CUDTSocket* s, const sockaddr_any& target_addr, int32_
        // -> pthread_create(...C(Snd|Rcv)Queue::worker...)
        s->m_Status = SRTS_OPENED;
    }
-   else if (s->m_Status != SRTS_OPENED)
-      throw CUDTException(MJ_NOTSUP, MN_ISCONNECTED, 0);
+   else
+   {
+       if (s->m_Status != SRTS_OPENED)
+           throw CUDTException(MJ_NOTSUP, MN_ISCONNECTED, 0);
+
+       // status = SRTS_OPENED, so family should be known already.
+       if (target_addr.family() != s->m_SelfAddr.family())
+       {
+           LOGP(mglog.Error, "srt_connect: socket is bound to a different family than target address");
+           throw CUDTException(MJ_NOTSUP, MN_INVAL, 0);
+       }
+   }
+
 
    // connect_complete() may be called before connect() returns.
    // So we need to update the status before connect() is called,
@@ -2474,6 +2485,7 @@ void CUDTUnited::updateMux(
                s->m_pUDT->m_pSndQueue = i->second.m_pSndQueue;
                s->m_pUDT->m_pRcvQueue = i->second.m_pRcvQueue;
                s->m_iMuxID = i->second.m_iID;
+               s->m_SelfAddr.family(addr.family());
                return;
             }
          }
@@ -2534,6 +2546,7 @@ void CUDTUnited::updateMux(
    sockaddr_any sa;
    m.m_pChannel->getSockAddr((sa));
    m.m_iPort = sa.hport();
+   s->m_SelfAddr = sa; // Will be also completed later, but here it's needed for later checks
 
    m.m_pTimer = new CTimer;
 

testing/testmedia.cpp

@@ -1125,15 +1125,27 @@ void SrtCommon::Error(string src, int reason, int force_result)
     throw TransmissionError("error: " + src + ": " + message);
 }
 
-void SrtCommon::SetupRendezvous(string adapter, int port)
+void SrtCommon::SetupRendezvous(string adapter, string host, int port)
 {
+    sockaddr_any target = CreateAddr(host, port);
+    if (target.family() == AF_UNSPEC)
+    {
+        Error("Unable to resolve target host: " + host);
+    }
+
     bool yes = true;
     srt_setsockopt(m_sock, 0, SRTO_RENDEZVOUS, &yes, sizeof yes);
 
     const int outport = m_outgoing_port ? m_outgoing_port : port;
 
-    auto localsa = CreateAddr(adapter, outport);
-    Verb() << "Binding a server on " << adapter << ":" << outport << " ...";
+    // Prefer the same IPv as target host
+    auto localsa = CreateAddr(adapter, outport, target.family());
+    string showhost = adapter;
+    if (showhost == "")
+        showhost = "ANY";
+    if (target.family() == AF_INET6)
+        showhost = "[" + showhost + "]";
+    Verb() << "Binding rendezvous: " << showhost << ":" << outport << " ...";
     int stat = srt_bind(m_sock, localsa.get(), localsa.size());
     if (stat == SRT_ERROR)
     {

testing/testmedia.hpp

@@ -125,7 +125,7 @@ class SrtCommon
     void PrepareClient();
     void SetupAdapter(const std::string& host, int port);
     void ConnectClient(string host, int port);
-    void SetupRendezvous(string adapter, int port);
+    void SetupRendezvous(string adapter, string host, int port);
 
     void OpenServer(string host, int port, int backlog = 1)
     {
@@ -140,7 +140,7 @@ class SrtCommon
     void OpenRendezvous(string adapter, string host, int port)
     {
         PrepareClient();
-        SetupRendezvous(adapter, port);
+        SetupRendezvous(adapter, host, port);
         ConnectClient(host, port);
     }