pw_rpc: Expose integration test socket

Exposes the socket file descriptor for socket-based RPC integration
testing servers/clients to enable socket configuration.

Change-Id: I04d0cb8674a10436da926a07347182c7c844ac59
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/91942
Pigweed-Auto-Submit: Armando Montanez <amontanez@google.com>
Reviewed-by: Erik Gilling <konkers@google.com>
Commit-Queue: Auto-Submit <auto-submit@pigweed.google.com.iam.gserviceaccount.com>

pw_rpc/integration_testing.cc

@@ -31,6 +31,8 @@ unit_test::LoggingEventHandler log_test_events;
 
 Client& client() { return context.client(); }
 
+int GetClientSocketFd() { return context.GetSocketFd(); }
+
 void SetEgressChannelManipulator(ChannelManipulator* new_channel_manipulator) {
   context.SetEgressChannelManipulator(new_channel_manipulator);
 }

pw_rpc/public/pw_rpc/integration_test_socket_client.h

@@ -47,6 +47,8 @@ class SocketClientContext {
     return OkStatus();
   }
 
+  int GetSocketFd() { return stream_.connection_fd(); }
+
   void SetEgressChannelManipulator(
       ChannelManipulator* new_channel_manipulator) {
     channel_output_with_manipulator_.set_channel_manipulator(

pw_rpc/public/pw_rpc/integration_testing.h

@@ -86,6 +86,10 @@ void SetIngressChannelManipulator(ChannelManipulator* new_channel_manipulator);
 // Returns the global RPC client for integration test use.
 Client& client();
 
+// The file descriptor for the socket associated with the client. This may be
+// used to configure socket options.
+int GetClientSocketFd();
+
 // Initializes logging and the global RPC client for integration testing. Starts
 // a background thread that processes incoming.
 Status InitializeClient(int argc,

pw_rpc/system_server/public/pw_rpc_system_server/socket.h

@@ -20,4 +20,8 @@ namespace pw::rpc::system_server {
 // Sets the port to use for pw::rpc::system_server backends that use sockets.
 void set_socket_port(uint16_t port);
 
+// The file descriptor for the socket associated with the server. This may be
+// used to configure socket options.
+int GetServerSocketFd();
+
 }  // namespace pw::rpc::system_server

pw_stream/docs.rst

@@ -415,6 +415,11 @@ Implementations
   ``StdFileReader`` wraps an ``std::ifstream`` with the :cpp:class:`Reader`
   interface.
 
+.. cpp:class:: SocketStream : public NonSeekableReaderWriter
+
+  ``SocketStream`` wraps posix-style sockets with the :cpp:class:`Reader` and
+  :cpp:class:`Writer` interfaces.
+
 ------------------
 Why use pw_stream?
 ------------------

pw_stream/public/pw_stream/socket_stream.h

@@ -38,6 +38,13 @@ class SocketStream : public NonSeekableReaderWriter {
   // Close the socket stream and release all resources
   void Close();
 
+  // Exposes the file descriptor for the active connection. This is exposed to
+  // allow configuration and introspection of this socket's current
+  // configuration using setsockopt() and getsockopt().
+  //
+  // Returns -1 if there is no active connection.
+  int connection_fd() { return connection_fd_; }
+
  private:
   static constexpr int kInvalidFd = -1;
 
@@ -47,7 +54,7 @@ class SocketStream : public NonSeekableReaderWriter {
 
   uint16_t listen_port_ = 0;
   int socket_fd_ = kInvalidFd;
-  int conn_fd_ = kInvalidFd;
+  int connection_fd_ = kInvalidFd;
   struct sockaddr_in sockaddr_client_ = {};
 };
 

pw_stream/socket_stream.cc

@@ -70,16 +70,16 @@ Status SocketStream::Serve(uint16_t port) {
 
   socklen_t len = sizeof(sockaddr_client_);
 
-  conn_fd_ =
+  connection_fd_ =
       accept(socket_fd_, reinterpret_cast<sockaddr*>(&sockaddr_client_), &len);
-  if (conn_fd_ < 0) {
+  if (connection_fd_ < 0) {
     return Status::Unknown();
   }
   return OkStatus();
 }
 
 Status SocketStream::SocketStream::Connect(const char* host, uint16_t port) {
-  conn_fd_ = socket(AF_INET, SOCK_STREAM, 0);
+  connection_fd_ = socket(AF_INET, SOCK_STREAM, 0);
 
   sockaddr_in addr;
   addr.sin_family = AF_INET;
@@ -94,7 +94,9 @@ Status SocketStream::SocketStream::Connect(const char* host, uint16_t port) {
     return Status::InvalidArgument();
   }
 
-  if (connect(conn_fd_, reinterpret_cast<sockaddr*>(&addr), sizeof(addr)) < 0) {
+  if (connect(connection_fd_,
+              reinterpret_cast<sockaddr*>(&addr),
+              sizeof(addr)) < 0) {
     PW_LOG_ERROR(
         "Failed to connect to %s:%d: %s", host, port, std::strerror(errno));
     return Status::Unknown();
@@ -109,17 +111,17 @@ void SocketStream::Close() {
     socket_fd_ = kInvalidFd;
   }
 
-  if (conn_fd_ != kInvalidFd) {
-    close(conn_fd_);
-    conn_fd_ = kInvalidFd;
+  if (connection_fd_ != kInvalidFd) {
+    close(connection_fd_);
+    connection_fd_ = kInvalidFd;
   }
 }
 
 Status SocketStream::DoWrite(std::span<const std::byte> data) {
   // Use MSG_NOSIGNAL to avoid getting a SIGPIPE signal when the remote
   // peer drops the connection.
   ssize_t bytes_sent =
-      send(conn_fd_, data.data(), data.size_bytes(), MSG_NOSIGNAL);
+      send(connection_fd_, data.data(), data.size_bytes(), MSG_NOSIGNAL);
 
   if (bytes_sent < 0 || static_cast<size_t>(bytes_sent) != data.size()) {
     if (errno == EPIPE) {
@@ -134,7 +136,7 @@ Status SocketStream::DoWrite(std::span<const std::byte> data) {
 }
 
 StatusWithSize SocketStream::DoRead(ByteSpan dest) {
-  ssize_t bytes_rcvd = recv(conn_fd_, dest.data(), dest.size_bytes(), 0);
+  ssize_t bytes_rcvd = recv(connection_fd_, dest.data(), dest.size_bytes(), 0);
   if (bytes_rcvd < 0) {
     return StatusWithSize::Unknown();
   }

targets/host/system_rpc_server.cc

@@ -43,6 +43,8 @@ void set_socket_port(uint16_t new_socket_port) {
   socket_port = new_socket_port;
 }
 
+int GetServerSocketFd() { return socket_stream.connection_fd(); }
+
 void Init() {
   log_basic::SetOutput([](std::string_view log) {
     std::fprintf(stderr, "%.*s\n", static_cast<int>(log.size()), log.data());