From ed848e9de267fcfdbe1cb7294b2e408d85a33575 Mon Sep 17 00:00:00 2001
From: Miguel Company <miguelcompany@eprosima.com>
Date: Wed, 8 May 2024 16:27:44 +0200
Subject: [PATCH] Refs #20972. Applying changes on CreateInputChannelResource.

Signed-off-by: Miguel Company <miguelcompany@eprosima.com>
---
 .../rtps/transport/UDPTransportInterface.cpp  | 55 +++++++++++++++----
 src/cpp/rtps/transport/UDPv4Transport.cpp     |  4 --
 src/cpp/rtps/transport/UDPv6Transport.cpp     |  4 --
 3 files changed, 43 insertions(+), 20 deletions(-)

diff --git a/src/cpp/rtps/transport/UDPTransportInterface.cpp b/src/cpp/rtps/transport/UDPTransportInterface.cpp
index ecc5885e578..0151b2976aa 100644
--- a/src/cpp/rtps/transport/UDPTransportInterface.cpp
+++ b/src/cpp/rtps/transport/UDPTransportInterface.cpp
@@ -146,6 +146,35 @@ static uint32_t try_setting_send_buffer_size(
     return minimum_buffer_value;
 }
 
+/**
+ * @brief Set the receive buffer size of the socket to the highest possible value the system allows.
+ *
+ * @param socket The socket on which to set the receive buffer size.
+ * @param initial_buffer_value The initial value to try to set.
+ * @param minimum_buffer_value The minimum value to set.
+ *
+ * @return The final value set.
+ */
+static uint32_t try_setting_receive_buffer_size(
+        asio::ip::udp::socket& socket,
+        uint32_t initial_buffer_value,
+        uint32_t minimum_buffer_value)
+{
+    // Try to set the highest possible value the system allows
+    for (auto recv_size = initial_buffer_value; recv_size >= minimum_buffer_value; recv_size /= 2)
+    {
+        asio::error_code ec;
+        socket_base::receive_buffer_size option(static_cast<int32_t>(recv_size));
+        socket.set_option(option, ec);
+        if (!ec)
+        {
+            return recv_size;
+        }
+    }
+
+    return minimum_buffer_value;
+}
+
 void UDPTransportInterface::configure_send_buffer_size()
 {
     asio::error_code ec;
@@ -221,23 +250,14 @@ void UDPTransportInterface::configure_receive_buffer_size()
     if (receive_buffer_size < minimum_socket_buffer)
     {
         receive_buffer_size = minimum_socket_buffer;
-        set_receive_buffer_size(receive_buffer_size);
     }
 
     // Try to set the highest possible value the system allows
-    for (; receive_buffer_size >= minimum_socket_buffer; receive_buffer_size /= 2)
-    {
-        socket_base::receive_buffer_size option(static_cast<int32_t>(receive_buffer_size));
-        socket.set_option(option, ec);
-        if (!ec)
-        {
-            set_receive_buffer_size(receive_buffer_size);
-            break;
-        }
-    }
+    receive_buffer_size = try_setting_receive_buffer_size(socket, receive_buffer_size, minimum_socket_buffer);
+    set_receive_buffer_size(receive_buffer_size);
 
     // Keep final configuration value
-    mReceiveBufferSize = configuration()->receiveBufferSize;
+    mReceiveBufferSize = receive_buffer_size;
 
     // Inform the user if the desired value could not be set
     if (initial_value != 0 && mReceiveBufferSize != initial_value)
@@ -334,6 +354,17 @@ UDPChannelResource* UDPTransportInterface::CreateInputChannelResource(
 {
     eProsimaUDPSocket unicastSocket = OpenAndBindInputSocket(sInterface,
                     IPLocator::getPhysicalPort(locator), is_multicast);
+    if (mReceiveBufferSize != 0)
+    {
+        uint32_t configured_value;
+        configured_value = try_setting_receive_buffer_size(unicastSocket, mReceiveBufferSize, maxMsgSize);
+        if (configured_value != mReceiveBufferSize)
+        {
+            EPROSIMA_LOG_WARNING(RTPS_MSG_OUT, "UDPTransport receiveBufferSize could not be set to the desired value. "
+                    << "Using " << configured_value << " instead of " << mReceiveBufferSize);
+        }
+    }
+
     UDPChannelResource* p_channel_resource = new UDPChannelResource(this, unicastSocket, maxMsgSize, locator,
                     sInterface, receiver, configuration()->get_thread_config_for_port(locator.port));
     return p_channel_resource;
diff --git a/src/cpp/rtps/transport/UDPv4Transport.cpp b/src/cpp/rtps/transport/UDPv4Transport.cpp
index a941072fe34..7951d2f7607 100644
--- a/src/cpp/rtps/transport/UDPv4Transport.cpp
+++ b/src/cpp/rtps/transport/UDPv4Transport.cpp
@@ -393,10 +393,6 @@ eProsimaUDPSocket UDPv4Transport::OpenAndBindInputSocket(
 {
     eProsimaUDPSocket socket = createUDPSocket(io_service_);
     getSocketPtr(socket)->open(generate_protocol());
-    if (mReceiveBufferSize != 0)
-    {
-        getSocketPtr(socket)->set_option(socket_base::receive_buffer_size(mReceiveBufferSize));
-    }
 
     if (is_multicast)
     {
diff --git a/src/cpp/rtps/transport/UDPv6Transport.cpp b/src/cpp/rtps/transport/UDPv6Transport.cpp
index 81ac92b5bac..3e40aa9001c 100644
--- a/src/cpp/rtps/transport/UDPv6Transport.cpp
+++ b/src/cpp/rtps/transport/UDPv6Transport.cpp
@@ -394,10 +394,6 @@ eProsimaUDPSocket UDPv6Transport::OpenAndBindInputSocket(
 {
     eProsimaUDPSocket socket = createUDPSocket(io_service_);
     getSocketPtr(socket)->open(generate_protocol());
-    if (mReceiveBufferSize != 0)
-    {
-        getSocketPtr(socket)->set_option(socket_base::receive_buffer_size(mReceiveBufferSize));
-    }
 
     if (is_multicast)
     {