Update DcsSocket to dynamically determine tx_port if none is provided

Sources/DcsInterface/DcsInterface.cpp

@@ -6,7 +6,7 @@
 #include "StringUtilities.h"
 
 DcsInterface::DcsInterface(const DcsConnectionSettings &settings)
-    : dcs_socket_(settings.rx_port, settings.tx_port, settings.ip_address), connection_settings_(settings) {
+    : dcs_socket_(settings.ip_address, settings.rx_port, settings.tx_port), connection_settings_(settings) {
     // Send a reset to request a resend of data in case DCS mission is already running.
     send_dcs_reset_command();
 }

Sources/DcsInterface/DcsSocket.cpp

@@ -11,7 +11,7 @@
 // Set default timeout for socket.
 DWORD socket_timeout_ms = 100;
 
-DcsSocket::DcsSocket(const std::string &rx_port, const std::string &tx_port, const std::string &ip_address) {
+DcsSocket::DcsSocket(const std::string &ip_address, const std::string &rx_port, const std::string &tx_port) {
     // Detect any missing input settings.
     if (rx_port.empty() || tx_port.empty() || ip_address.empty()) {
         const std::string error_msg =
@@ -60,37 +60,42 @@ DcsSocket::DcsSocket(const std::string &rx_port, const std::string &tx_port, con
         throw std::runtime_error(error_msg);
     }
 
-    // Define send destination port.
-    getaddrinfo(ip_address.c_str(), tx_port.c_str(), &hints, &dest_port_);
+    if (tx_port != "dynamic") {
+        // Define send destination port.
+        addrinfo *send_to_port;
+        getaddrinfo(ip_address.c_str(), tx_port.c_str(), &hints, &send_to_port);
+        dest_addr_ = *send_to_port->ai_addr;
+        dest_addr_len_ = static_cast<int>(send_to_port->ai_addrlen);
+        freeaddrinfo(send_to_port);
+    }
 }
 
 DcsSocket::~DcsSocket() {
     // Delete opened socket.
-    freeaddrinfo(dest_port_);
     closesocket(socket_id_);
     WSACleanup();
 }
 
 std::stringstream DcsSocket::DcsReceive() {
     // Sender address - dummy variable as it is unused outside recvfrom.
-    sockaddr_in sender_addr;
+    sockaddr sender_addr;
     int sender_addr_size = sizeof(sender_addr);
 
     // Receive next UDP message.
     constexpr int MAX_UDP_MSG_SIZE = 1024; // Maximum UDP buffer size to read.
     char msg[MAX_UDP_MSG_SIZE] = {};
-    (void)recvfrom(socket_id_, msg, MAX_UDP_MSG_SIZE, 0, (SOCKADDR *)&sender_addr, &sender_addr_size);
+    (void)recvfrom(socket_id_, msg, MAX_UDP_MSG_SIZE, 0, &sender_addr, &sender_addr_size);
+
+    if (dest_addr_len_ == 0) {
+        dest_addr_ = sender_addr;
+        dest_addr_len_ = sender_addr_size;
+    }
 
     std::stringstream ss;
     ss << msg;
     return ss;
 }
 
 void DcsSocket::DcsSend(const std::string &message) {
-    (void)sendto(socket_id_,
-                 message.c_str(),
-                 static_cast<int>(message.length()),
-                 0,
-                 dest_port_->ai_addr,
-                 static_cast<int>(dest_port_->ai_addrlen));
+    (void)sendto(socket_id_, message.c_str(), static_cast<int>(message.length()), 0, &dest_addr_, dest_addr_len_);
 }

Sources/DcsInterface/DcsSocket.h

@@ -7,16 +7,16 @@
 
 class DcsSocket {
   public:
-    // Binds a UDP socket to the rx port and also intializes the destination address using the tx port.
+    // Binds a UDP socket to the rx port and also initializes the destination address using the tx port.
     /**
      * @brief Construct a new Dcs Socket object bound to the rx port and initializes the destination address using the
-     * tx port.
+     * tx port if provided, or determines tx_port address dynamically if not.
      *
-     * @param rx_port UDP receive port.
-     * @param tx_port UDP transmit port.
      * @param tx_ip_address UDP transmit IP address.
+     * @param rx_port UDP receive port.
+     * @param tx_port UDP transmit port, defaults to dynamic (use recvfrom address) if not provided.
      */
-    DcsSocket(const std::string &rx_port, const std::string &tx_port, const std::string &ip_address);
+    DcsSocket(const std::string &ip_address, const std::string &rx_port, const std::string &tx_port = "dynamic");
 
     /**
      * @brief Destroy the Dcs Socket object
@@ -45,6 +45,7 @@ class DcsSocket {
     void DcsSend(const std::string &message);
 
   private:
-    SOCKET socket_id_;    // Socket which is binded to the rx port.
-    addrinfo *dest_port_; // UDP address info for port which will be transmitted to.
+    SOCKET socket_id_;      // Socket which is binded to the rx port.
+    sockaddr dest_addr_;    // UDP address info for port which will be transmitted to.
+    int dest_addr_len_ = 0; // Size of dest address.
 };

Sources/Test/DcsInterfaceTest.cpp

@@ -13,7 +13,7 @@ TEST(DcsInterfaceTest, invalid_connection_port_settings) {
 
 TEST(DcsInterfaceTest, dcs_reset_command_on_construction) {
     DcsConnectionSettings connection_settings = {"1908", "1909", "127.0.0.1"};
-    DcsSocket mock_dcs(connection_settings.tx_port, connection_settings.rx_port, connection_settings.ip_address);
+    DcsSocket mock_dcs(connection_settings.ip_address, connection_settings.tx_port, connection_settings.rx_port);
     DcsInterface dcs_interface(connection_settings);
 
     // Test that the reset message "R" is received by DCS on creation of DcsInterface.
@@ -25,7 +25,7 @@ class DcsInterfaceTestFixture : public ::testing::Test {
   public:
     DcsInterfaceTestFixture()
         : // Mock DCS socket uses the reverse rx and tx ports of dcs_interface so it can communicate with it.
-          mock_dcs(connection_settings.tx_port, connection_settings.rx_port, connection_settings.ip_address),
+          mock_dcs(connection_settings.ip_address, connection_settings.tx_port, connection_settings.rx_port),
           dcs_interface(connection_settings) {
 
         // Consume intial reset command sent to to mock_dcs.

Sources/Test/DcsSocketTest.cpp

@@ -9,17 +9,17 @@ namespace test {
 TEST(DcsSocketTest, empty_connection_settings) { EXPECT_THROW(DcsSocket dcs_socket("", "", ""), std::runtime_error); }
 
 TEST(DcsSocketTest, invalid_connection_port_settings) {
-    EXPECT_THROW(DcsSocket dcs_socket("19ab", "abc", "127.0.0.1"), std::runtime_error);
+    EXPECT_THROW(DcsSocket dcs_socket("127.0.0.1", "19ab", "abc"), std::runtime_error);
 }
 
 TEST(DcsSocketTest, invalid_connection_ip_addr_settings) {
-    EXPECT_THROW(DcsSocket dcs_socket("1908", "1909", "127001"), std::runtime_error);
+    EXPECT_THROW(DcsSocket dcs_socket("127001", "1908", "1909"), std::runtime_error);
 }
 
 class DcsSocketTestFixture : public ::testing::Test {
   public:
     DcsSocketTestFixture()
-        : sender_socket("1788", common_port, ip_address), receiver_socket(common_port, "1790", ip_address) {}
+        : sender_socket(ip_address, "1788", common_port), receiver_socket(ip_address, common_port, "1790") {}
 
     DcsSocket sender_socket;
     DcsSocket receiver_socket;
@@ -36,12 +36,27 @@ TEST_F(DcsSocketTestFixture, send_and_receive) {
 
 TEST_F(DcsSocketTestFixture, unavailable_port_bind) {
     // Expect exception thrown if try to bind a new socket to same rx_port.
-    EXPECT_THROW(DcsSocket duplicate_socket(common_port, "1801", ip_address), std::runtime_error);
+    EXPECT_THROW(DcsSocket duplicate_socket(ip_address, common_port, "1801"), std::runtime_error);
 }
 
 TEST_F(DcsSocketTestFixture, receive_timeout) {
     std::stringstream ss_received = receiver_socket.DcsReceive();
     // Expect timeout after 100 msec and return of empty string.
     EXPECT_EQ(ss_received.str(), "");
 }
+
+TEST_F(DcsSocketTestFixture, dynamic_tx_port_discovery) {
+    const std::string new_common_port = "1791";
+    DcsSocket server_socket(ip_address, "1792", new_common_port);
+    DcsSocket client_socket(ip_address, new_common_port);
+    const std::string test_msg_a = "test_a";
+    server_socket.DcsSend(test_msg_a);
+    std::stringstream client_received_ss = client_socket.DcsReceive();
+    EXPECT_EQ(test_msg_a, client_received_ss.str());
+    // Expect client socket to have dynamically set tx_port to sender_socket's bound port.
+    const std::string test_msg_b = "test_b";
+    client_socket.DcsSend(test_msg_b);
+    std::stringstream server_received_ss = server_socket.DcsReceive();
+    EXPECT_EQ(test_msg_b, server_received_ss.str());
+}
 } // namespace test

Sources/Test/StreamdeckContextTest.cpp

@@ -48,7 +48,7 @@ class StreamdeckContextTestFixture : public ::testing::Test {
   public:
     StreamdeckContextTestFixture()
         : // Mock DCS socket uses the reverse rx and tx ports of dcs_interface so it can communicate with it.
-          mock_dcs(connection_settings.tx_port, connection_settings.rx_port, connection_settings.ip_address),
+          mock_dcs(connection_settings.ip_address, connection_settings.tx_port, connection_settings.rx_port),
           dcs_interface(connection_settings), fixture_context(fixture_context_id) {
 
         // Consume intial reset command sent to to mock_dcs.