[20438] LARGE_DATA Participants logic with same listening ports (backport #4396)

src/cpp/rtps/transport/TCPTransportInterface.cpp

@@ -716,10 +716,31 @@ bool TCPTransportInterface::OpenOutputChannel(
             listening_port = config->listening_ports.front();
         }
 
+        bool local_lower_interface = false;
+        if (IPLocator::getPhysicalPort(physical_locator) == listening_port)
+        {
+            std::vector<Locator> list;
+            std::vector<fastrtps::rtps::IPFinder::info_IP> local_interfaces;
+            get_ips(local_interfaces);
+            for (const auto& interface_it : local_interfaces)
+            {
+                Locator interface_loc(interface_it.locator);
+                interface_loc.port = physical_locator.port;
+                if (is_interface_allowed(interface_loc))
+                {
+                    list.push_back(interface_loc);
+                }
+            }
+            if (!list.empty() && (list.front() < physical_locator))
+            {
+                local_lower_interface = true;
+            }
+        }
+
         // If the remote physical port is higher than our listening port, a new CONNECT channel needs to be created and connected
         // and the locator added to the send_resource_list.
         // If the remote physical port is lower than our listening port, only the locator needs to be added to the send_resource_list.
-        if (IPLocator::getPhysicalPort(physical_locator) > listening_port)
+        if (IPLocator::getPhysicalPort(physical_locator) > listening_port || local_lower_interface)
         {
             // Client side (either Server-Client or LARGE_DATA)
             EPROSIMA_LOG_INFO(OpenOutputChannel, "OpenOutputChannel: [CONNECT] (physical: "

test/unittest/transport/TCPv4Tests.cpp

@@ -2047,6 +2047,34 @@ TEST_F(TCPv4Tests, reconnect_after_open_port_failure)
     client_resource_list.clear();
 }
 
+// This test verifies that OpenOutputChannel correctly handles a remote locator with
+// same physical port as the local listening port.
+TEST_F(TCPv4Tests, opening_output_channel_with_same_locator_as_local_listening_port)
+{
+    TCPv4Transport transportUnderTest(descriptor);
+    transportUnderTest.init();
+
+    // Two locators with the same port as the local listening port, but different addresses
+    Locator_t lowerOutputChannelLocator;
+    lowerOutputChannelLocator.kind = LOCATOR_KIND_TCPv4;
+    lowerOutputChannelLocator.port = g_default_port;
+    IPLocator::setLogicalPort(lowerOutputChannelLocator, g_default_port);
+    Locator_t higherOutputChannelLocator = lowerOutputChannelLocator;
+    IPLocator::setIPv4(lowerOutputChannelLocator, 1, 1, 1, 1);
+    IPLocator::setIPv4(higherOutputChannelLocator, 255, 255, 255, 255);
+
+    SendResourceList send_resource_list;
+
+    // If the remote address is lower than the local one, no channel must be created but it must be added to the send_resource_list
+    ASSERT_TRUE(transportUnderTest.OpenOutputChannel(send_resource_list, lowerOutputChannelLocator));
+    ASSERT_FALSE(transportUnderTest.is_output_channel_open_for(lowerOutputChannelLocator));
+    ASSERT_EQ(send_resource_list.size(), 1);
+    // If the remote address is higher than the local one, a CONNECT channel must be created and added to the send_resource_list
+    ASSERT_TRUE(transportUnderTest.OpenOutputChannel(send_resource_list, higherOutputChannelLocator));
+    ASSERT_TRUE(transportUnderTest.is_output_channel_open_for(higherOutputChannelLocator));
+    ASSERT_EQ(send_resource_list.size(), 2);
+}
+
 void TCPv4Tests::HELPER_SetDescriptorDefaults()
 {
     descriptor.add_listener_port(g_default_port);

test/unittest/transport/TCPv6Tests.cpp

@@ -486,6 +486,33 @@ TEST_F(TCPv6Tests, reconnect_after_open_port_failure)
     client_resource_list.clear();
 }
 
+TEST_F(TCPv6Tests, opening_output_channel_with_same_locator_as_local_listening_port)
+{
+    descriptor.add_listener_port(g_default_port);
+    TCPv6Transport transportUnderTest(descriptor);
+    transportUnderTest.init();
+
+    // Two locators with the same port as the local listening port, but different addresses
+    Locator_t lowerOutputChannelLocator;
+    lowerOutputChannelLocator.kind = LOCATOR_KIND_TCPv6;
+    lowerOutputChannelLocator.port = g_default_port;
+    IPLocator::setLogicalPort(lowerOutputChannelLocator, g_default_port);
+    Locator_t higherOutputChannelLocator = lowerOutputChannelLocator;
+    IPLocator::setIPv6(lowerOutputChannelLocator, "::");
+    IPLocator::setIPv6(higherOutputChannelLocator, "ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff");
+
+    SendResourceList send_resource_list;
+
+    // If the remote address is lower than the local one, no channel must be created but it must be added to the send_resource_list
+    ASSERT_TRUE(transportUnderTest.OpenOutputChannel(send_resource_list, lowerOutputChannelLocator));
+    ASSERT_FALSE(transportUnderTest.is_output_channel_open_for(lowerOutputChannelLocator));
+    ASSERT_EQ(send_resource_list.size(), 1);
+    // If the remote address is higher than the local one, a CONNECT channel must be created and added to the send_resource_list
+    ASSERT_TRUE(transportUnderTest.OpenOutputChannel(send_resource_list, higherOutputChannelLocator));
+    ASSERT_TRUE(transportUnderTest.is_output_channel_open_for(higherOutputChannelLocator));
+    ASSERT_EQ(send_resource_list.size(), 2);
+}
+
 /*
    TEST_F(TCPv6Tests, send_and_receive_between_both_secure_ports)
    {