multiplex: Fix issue #165, enable ZRTP initialization with 3 or more streams in separate threads

src/media_stream.cc

@@ -285,6 +285,10 @@ rtp_error_t uvgrtp::media_stream::free_resources(rtp_error_t ret)
     media_          = nullptr;
     socket_         = nullptr;
 
+    if (zrtp_) {
+        zrtp_->set_zrtp_busy(false);
+    }
+
     return ret;
 }
 
@@ -381,7 +385,20 @@ rtp_error_t uvgrtp::media_stream::init(std::shared_ptr<uvgrtp::zrtp> zrtp)
             }
         }
     }
-
+    /* If ZRTP is already performing an MSM negotiation, wait for it to complete before starting a new one */
+    if (!perform_dh) {
+        auto start = std::chrono::system_clock::now();
+        while (zrtp_->is_zrtp_busy()) {
+            std::this_thread::sleep_for(std::chrono::milliseconds(10));
+            if (std::chrono::duration_cast<std::chrono::seconds>(std::chrono::system_clock::now() - start).count() > 10)
+            {
+                UVG_LOG_ERROR("Giving up on MSM after 10 seconds");
+                return free_resources(RTP_TIMEOUT);
+            }
+        }
+    }
+    
+    zrtp_->set_zrtp_busy(true);
     ret = RTP_OK;
     if ((ret = zrtp->init(rtp_->get_ssrc(), socket_, remote_sockaddr_, remote_sockaddr_ip6_, perform_dh, ipv6_)) != RTP_OK) {
         UVG_LOG_WARN("Failed to initialize ZRTP for media stream!");
@@ -394,6 +411,7 @@ rtp_error_t uvgrtp::media_stream::init(std::shared_ptr<uvgrtp::zrtp> zrtp)
     if ((ret = init_srtp_with_zrtp(rce_flags_, SRTCP, srtcp_, zrtp)) != RTP_OK)
         return free_resources(ret);
 
+    zrtp_->set_zrtp_busy(false);
     zrtp->dh_has_finished(); // only after the DH stream has gotten its keys, do we let non-DH stream perform ZRTP
     install_packet_handlers();
 

src/zrtp.cc

@@ -45,7 +45,8 @@ uvgrtp::zrtp::zrtp():
     confack_(nullptr),
     hello_len_(0),
     commit_len_(0),
-    dh_len_(0)
+    dh_len_(0),
+    zrtp_busy_(false)
 {
     cctx_.sha256 = new uvgrtp::crypto::sha256;
     cctx_.dh     = new uvgrtp::crypto::dh;
@@ -930,7 +931,6 @@ rtp_error_t uvgrtp::zrtp::init_msm(uint32_t ssrc, std::shared_ptr<uvgrtp::socket
             return ret;
         }
     }
-
     return RTP_OK;
 }
 

src/zrtp.hh

@@ -90,6 +90,15 @@ namespace uvgrtp {
                 dh_finished_ = true;
             }
 
+            inline bool is_zrtp_busy() const
+            {
+                return zrtp_busy_;
+            }
+            inline void set_zrtp_busy(bool status)
+            {
+                zrtp_busy_ = status;
+            }
+
         private:
             /* Initialize ZRTP session between us and remote using Diffie-Hellman Mode
              *
@@ -209,7 +218,7 @@ namespace uvgrtp {
 
             std::mutex state_mutex_;
             bool dh_finished_ = false;
-
+            bool zrtp_busy_;
 
     };
 }