Add source port parameter for RTPWriter

This is required if we want to support hole punching

src/lib.cc

@@ -62,6 +62,32 @@ RTPWriter *RTPContext::createWriter(std::string dstAddr, int dstPort, rtp_format
     if ((writer = createWriter(dstAddr, dstPort)) == nullptr)
         return nullptr;
 
+    conns_.insert(std::pair<int, RTPConnection *>(writer->getId(), writer));
+    writer->setPayloadType(fmt);
+    return writer;
+}
+
+RTPWriter *RTPContext::createWriter(std::string dstAddr, int dstPort, int srcPort)
+{
+    RTPWriter *writer = new RTPWriter(dstAddr, dstPort, srcPort);
+
+    if (!writer) {
+        std::cerr << "Failed to create RTPWriter for " << dstAddr << ":" << dstPort << "!" << std::endl;
+        return nullptr;
+    }
+
+    conns_.insert(std::pair<int, RTPConnection *>(writer->getId(), writer));
+    return writer;
+}
+
+RTPWriter *RTPContext::createWriter(std::string dstAddr, int dstPort, int srcPort, rtp_format_t fmt)
+{
+    RTPWriter *writer = nullptr;
+
+    if ((writer = createWriter(dstAddr, dstPort, srcPort)) == nullptr)
+        return nullptr;
+
+    conns_.insert(std::pair<int, RTPConnection *>(writer->getId(), writer));
     writer->setPayloadType(fmt);
     return writer;
 }

src/lib.hh

@@ -18,11 +18,13 @@ public:
     RTPReader *createReader(std::string srcAddr, int srcPort);
     RTPReader *createReader(std::string srcAddr, int srcPort, rtp_format_t fmt);
 
-    /* Open connection for writing RTP packets to dstAddr:dstPort 
+    /* Open connection for writing RTP packets to dstAddr:dstPort
      *
      * Packets can be sent by calling RTPWriter::pushFrame() */
     RTPWriter *createWriter(std::string dstAddr, int dstPort);
     RTPWriter *createWriter(std::string dstAddr, int dstPort, rtp_format_t fmt);
+    RTPWriter *createWriter(std::string dstAddr, int dstPort, int srcPort);
+    RTPWriter *createWriter(std::string dstAddr, int dstPort, int srcPort, rtp_format_t fmt);
 
     RTPConnection *openConnection(std::string dstAddr, int dstPort, int srcPort);
     int closeConnection(int id);

src/writer.cc

@@ -2,18 +2,26 @@
 #include <cstring>
 #include <iostream>
 
-#include "writer.hh"
+#include "debug.hh"
 #include "rtp_opus.hh"
 #include "rtp_hevc.hh"
 #include "rtp_generic.hh"
+#include "writer.hh"
 
 RTPWriter::RTPWriter(std::string dstAddr, int dstPort):
     RTPConnection(false),
     dstAddr_(dstAddr),
-    dstPort_(dstPort)
+    dstPort_(dstPort),
+    srcPort_(0)
 {
 }
 
+RTPWriter::RTPWriter(std::string dstAddr, int dstPort, int srcPort):
+    RTPWriter(dstAddr, dstPort)
+{
+    srcPort_ = srcPort;
+}
+
 RTPWriter::~RTPWriter()
 {
 }
@@ -21,10 +29,34 @@ RTPWriter::~RTPWriter()
 int RTPWriter::start()
 {
     if ((socket_ = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
-        perror("RTPConnection::open");
+        LOG_ERROR("Creating socket failed: %s", strerror(errno));
         return RTP_SOCKET_ERROR;
     }
 
+    /* if source port is not 0, writer should be bind to that port so that outgoing packet
+     * has a correct source port (important for hole punching purposes) */
+    if (srcPort_ != 0) {
+        int enable = 1;
+        if (setsockopt(socket_, SOL_SOCKET, SO_REUSEADDR, &enable, sizeof(int)) < 0) {
+            perror("setsockopt(SO_REUSEADDR) failed");
+            return RTP_GENERIC_ERROR;
+        }
+
+        LOG_DEBUG("Binding to port %d (source port)", srcPort_);
+
+        sockaddr_in addrIn_;
+
+        memset(&addrIn_, 0, sizeof(addrIn_));
+        addrIn_.sin_family = AF_INET;
+        addrIn_.sin_addr.s_addr = htonl(INADDR_ANY);
+        addrIn_.sin_port = htons(srcPort_);
+
+        if (bind(socket_, (struct sockaddr *) &addrIn_, sizeof(addrIn_)) < 0) {
+            LOG_ERROR("Binding failed: %s", strerror(errno));
+            return RTP_BIND_ERROR;
+        }
+    }
+
     memset(&addrOut_, 0, sizeof(addrOut_));
     addrOut_.sin_family = AF_INET;
     inet_pton(AF_INET, dstAddr_.c_str(), &addrOut_.sin_addr);

src/writer.hh

@@ -8,6 +8,7 @@ class RTPWriter : public RTPConnection {
 
 public:
     RTPWriter(std::string dstAddr, int dstPort);
+    RTPWriter(std::string dstAddr, int dstPort, int srcPort);
     ~RTPWriter();
 
     // open socket for sending frames
@@ -24,5 +25,6 @@ public:
 private:
     std::string dstAddr_;
     int dstPort_;
+    int srcPort_;
     sockaddr_in addrOut_;
 };