Add ability to bound the session to user-specificied address

src/lib.cc

@@ -40,6 +40,14 @@ kvz_rtp::session *kvz_rtp::context::create_session(std::string address)
     return new kvz_rtp::session(address);
 }
 
+kvz_rtp::session *kvz_rtp::context::create_session(std::string remote_addr, std::string local_addr)
+{
+    if (remote_addr == "" || local_addr == "")
+        return nullptr;
+
+    return new kvz_rtp::session(remote_addr, local_addr);
+}
+
 rtp_error_t kvz_rtp::context::destroy_session(kvz_rtp::session *session)
 {
     if (!session)

src/lib.hh

@@ -10,9 +10,13 @@ namespace kvz_rtp {
             context();
             ~context();
 
-            /* Create new session if "addr" is unique or return pointer to previously created session */
+            /* Create a new session with remote participant */
             kvz_rtp::session *create_session(std::string addr);
 
+            /* Create a new session with remote participant
+             * Bind ourselves to interface pointed to by "local_addr" */
+            kvz_rtp::session *create_session(std::string remote_addr, std::string local_addr);
+
             /* Destroy session and all media streams
              *
              * Return RTP_INVALID_VALUE if "session" is nullptr

src/media_stream.cc

@@ -13,6 +13,7 @@ kvz_rtp::media_stream::media_stream(std::string addr, int src_port, int dst_port
 {
     fmt_      = fmt;
     addr_     = addr;
+    laddr_    = "";
     flags_    = flags;
     src_port_ = src_port;
     dst_port_ = dst_port;
@@ -21,6 +22,16 @@ kvz_rtp::media_stream::media_stream(std::string addr, int src_port, int dst_port
     ctx_config_.flags = flags;
 }
 
+kvz_rtp::media_stream::media_stream(
+    std::string remote_addr, std::string local_addr,
+    int src_port, int dst_port,
+    rtp_format_t fmt, int flags
+):
+    media_stream(remote_addr, src_port, dst_port, fmt, flags)
+{
+    laddr_ = local_addr;
+}
+
 kvz_rtp::media_stream::~media_stream()
 {
     receiver_->stop();
@@ -47,8 +58,23 @@ rtp_error_t kvz_rtp::media_stream::init_connection()
         LOG_ERROR("Failed to make the socket non-blocking!");
 #endif
 
-    if ((ret = socket_.bind(AF_INET, INADDR_ANY, src_port_)) != RTP_OK)
+    if (laddr_ != "") {
-        return ret;
+        sockaddr_in bind_addr = socket_.create_sockaddr(AF_INET, laddr_, src_port_);
+        socket_t socket       = socket_.get_raw_socket();
+
+        if (bind(socket, (struct sockaddr *)&bind_addr, sizeof(bind_addr)) == -1) {
+#ifdef __linux__
+            LOG_ERROR("Bind failed: %s!", strerror(errno));
+#else
+            LOG_ERROR("Bind failed!");
+            win_get_last_error();
+#endif
+            return RTP_BIND_ERROR;
+        }
+    } else {
+        if ((ret = socket_.bind(AF_INET, INADDR_ANY, src_port_)) != RTP_OK)
+            return ret;
+    }
 
     addr_out_ = socket_.create_sockaddr(AF_INET, addr_, dst_port_);
     socket_.set_sockaddr(addr_out_);

src/media_stream.hh

@@ -15,6 +15,7 @@ namespace kvz_rtp {
     class media_stream {
         public:
             media_stream(std::string addr, int src_port, int dst_port, rtp_format_t fmt, int flags);
+            media_stream(std::string remote_addr, std::string local_addr, int src_port, int dst_port, rtp_format_t fmt, int flags);
             ~media_stream();
 
             /* Initialize traditional RTP session
@@ -125,6 +126,7 @@ namespace kvz_rtp {
 
             sockaddr_in addr_out_;
             std::string addr_;
+            std::string laddr_;
             int src_port_;
             int dst_port_;
             rtp_format_t fmt_;

src/session.cc

@@ -5,10 +5,17 @@ kvz_rtp::session::session(std::string addr):
 #ifdef __RTP_CRYPTO__
     zrtp_(nullptr),
 #endif
-    addr_(addr)
+    addr_(addr),
+    laddr_("")
 {
 }
 
+kvz_rtp::session::session(std::string remote_addr, std::string local_addr):
+    session(remote_addr)
+{
+    laddr_ = local_addr;
+}
+
 kvz_rtp::session::~session()
 {
     for (auto&i : streams_) {
@@ -23,7 +30,19 @@ kvz_rtp::session::~session()
 
 kvz_rtp::media_stream *kvz_rtp::session::create_stream(int r_port, int s_port, rtp_format_t fmt, int flags)
 {
-    kvz_rtp::media_stream *stream = new kvz_rtp::media_stream(addr_, r_port, s_port, fmt, flags);
+    kvz_rtp::media_stream *stream = nullptr;
+
+    if (laddr_ == "")
+        stream = new kvz_rtp::media_stream(addr_, r_port, s_port, fmt, flags);
+    else
+        stream = new kvz_rtp::media_stream(addr_, laddr_, r_port, s_port, fmt, flags);
+
+    if (!stream) {
+        LOG_ERROR("Failed to create media stream for %s:%d -> %s:%d",
+            (laddr_ == "") ? "0.0.0.0" : laddr_.c_str(), s_port, addr_.c_str(), r_port
+        );
+        return nullptr;
+    }
 
 #ifdef __RTP_CRYPTO__
     int zrtp_flags = (RCE_SRTP | RCE_SRTP_KMNGMNT_ZRTP);

src/session.hh

@@ -11,6 +11,7 @@ namespace kvz_rtp {
     class session {
         public:
             session(std::string addr);
+            session(std::string remote_addr, std::string local_addr);
             ~session();
 
             /* Create bidirectional media stream for media format "fmt"
@@ -43,6 +44,9 @@ namespace kvz_rtp {
             /* Each RTP multimedia session is always IP-specific */
             std::string addr_;
 
+            /* If user so wishes, the session can be bound to a certain interface */
+            std::string laddr_;
+
             /* All media streams of this session */
             std::unordered_map<uint32_t, kvz_rtp::media_stream *> streams_;
     };