enh(Net): Allow passing raw fd's into ServerSocket (#4156)

* Allow creating ServerSocket's from fd's
* more sensible approach
* fix whitespace issue
* add test
* build fixes for windows

Net/include/Poco/Net/ServerSocket.h

@@ -60,6 +60,10 @@ class Net_API ServerSocket: public Socket
 		/// After successful construction, the server socket
 		/// is ready to accept connections.
 
+	static ServerSocket fromFileDescriptor(poco_socket_t fd);
+		// Creates a socket from an existing file descriptor.
+		// Ownership is taken by poco
+
 	virtual ~ServerSocket();
 		/// Destroys the ServerSocket.
 

Net/include/Poco/Net/Socket.h

@@ -85,6 +85,10 @@ class Net_API Socket
 
 #endif // POCO_NEW_STATE_ON_MOVE
 
+	static Socket fromFileDescriptor(poco_socket_t fd);
+		// Creates a socket from an existing file descriptor.
+		// Ownership is taken by poco
+
 	virtual ~Socket();
 		/// Destroys the Socket and releases the
 		/// SocketImpl.

Net/include/Poco/Net/SocketImpl.h

@@ -142,6 +142,13 @@ class Net_API SocketImpl: public Poco::RefCountedObject
 		/// If the library has not been built with IPv6 support,
 		/// a Poco::NotImplementedException will be thrown.
 
+	void useFileDescriptor(poco_socket_t fd);
+		/// Use a external file descriptor for the socket. Required to be careful
+		/// about what kind of file descriptor you're passing to make sure it's compatable
+		/// with how you plan on using it. These specifics are platform-specific.
+		/// Not valid to call this if the internal socket is already initialized.
+		/// Poco takes ownership of the file descriptor, closing it when this socket is closed.
+
 	virtual void listen(int backlog = 64);
 		/// Puts the socket into listening state.
 		///

Net/src/ServerSocket.cpp

@@ -57,6 +57,14 @@ ServerSocket::ServerSocket(SocketImpl* pImpl, bool ignore): Socket(pImpl)
 }
 
 
+ServerSocket ServerSocket::fromFileDescriptor(poco_socket_t fd)
+{
+	ServerSocket s;
+	s.impl()->useFileDescriptor(fd);
+	return s;
+}
+
+
 ServerSocket::~ServerSocket()
 {
 }

Net/src/Socket.cpp

@@ -54,6 +54,15 @@ Socket::Socket(const Socket& socket):
 	_pImpl->duplicate();
 }
 
+
+Socket Socket::fromFileDescriptor(poco_socket_t fd)
+{
+	Socket s;
+	s.impl()->useFileDescriptor(fd);
+	return s;
+}
+
+
 #if POCO_NEW_STATE_ON_MOVE
 
 Socket::Socket(Socket&& socket):

Net/src/SocketImpl.cpp

@@ -276,6 +276,14 @@ void SocketImpl::bind6(const SocketAddress& address, bool reuseAddress, bool reu
 }
 
 
+void SocketImpl::useFileDescriptor(poco_socket_t fd)
+{
+	poco_assert (_sockfd == POCO_INVALID_SOCKET);
+
+	_sockfd = fd;
+}
+
+
 void SocketImpl::listen(int backlog)
 {
 	if (_sockfd == POCO_INVALID_SOCKET) throw InvalidSocketException();

Net/testsuite/src/EchoServer.cpp

@@ -9,6 +9,7 @@
 
 
 #include "EchoServer.h"
+#include "Poco/Net/ServerSocket.h"
 #include "Poco/Net/StreamSocket.h"
 #include "Poco/Net/SocketAddress.h"
 #include "Poco/Timespan.h"
@@ -42,6 +43,17 @@ EchoServer::EchoServer(const Poco::Net::SocketAddress& address):
 }
 
 
+EchoServer::EchoServer(const Poco::Net::ServerSocket& sock):
+	_socket(sock),
+	_thread("EchoServer"),
+	_stop(false),
+	_done(false)
+{
+	_thread.start(*this);
+	_ready.wait();
+}
+
+
 EchoServer::~EchoServer()
 {
 	_stop = true;

Net/testsuite/src/EchoServer.h

@@ -31,6 +31,9 @@ class EchoServer: public Poco::Runnable
 	EchoServer(const Poco::Net::SocketAddress& address);
 		/// Creates the EchoServer using the given address.
 
+	EchoServer(const Poco::Net::ServerSocket& sock);
+		/// Creates the EchoServer using the already created socket
+
 	~EchoServer();
 		/// Destroys the EchoServer.
 

Net/testsuite/src/SocketTest.cpp

@@ -598,6 +598,51 @@ void SocketTest::testUnixLocalAbstract()
 }
 
 
+void SocketTest::testUseFd()
+{
+#ifdef POCO_OS_FAMILY_WINDOWS
+	struct addrinfo addr_hint = {};
+	addr_hint.ai_family = AF_INET;
+	addr_hint.ai_socktype = SOCK_STREAM;
+	addr_hint.ai_protocol = IPPROTO_TCP;
+	addr_hint.ai_flags = AI_PASSIVE;
+	struct addrinfo* addr_result;
+	getaddrinfo(nullptr, "0", &addr_hint, &addr_result);
+	poco_socket_t listenfd = socket(addr_result->ai_family, addr_result->ai_socktype, addr_result->ai_protocol);
+	bind(listenfd, addr_result->ai_addr, (int)addr_result->ai_addrlen);
+	freeaddrinfo(addr_result);
+	listen(listenfd, SOMAXCONN);
+	SOCKADDR_IN serv_addr;
+	int addr_len = sizeof(serv_addr);
+	getsockname(listenfd, (SOCKADDR*)&serv_addr, &addr_len);
+	auto server_port = ntohs(serv_addr.sin_port);
+#elif defined(POCO_OS_FAMILY_UNIX)
+	poco_socket_t listenfd = socket(AF_INET, SOCK_STREAM, 0);
+	struct sockaddr_in serv_addr = {};
+	serv_addr.sin_family = AF_INET;
+	serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
+	serv_addr.sin_port = htons(0);
+	bind(listenfd, (struct sockaddr*)&serv_addr, sizeof(serv_addr));
+	listen(listenfd, 1);
+	socklen_t len = sizeof(serv_addr);
+	getsockname(listenfd, (struct sockaddr*)&serv_addr, &len);
+	auto server_port = ntohs(serv_addr.sin_port);
+#else
+	std::cout << "[USE FD TEST DISABLED]";
+	return;
+#endif
+	EchoServer server(ServerSocket::fromFileDescriptor(listenfd));
+	StreamSocket ss;
+	ss.connect(SocketAddress("127.0.0.1", server_port));
+	int n = ss.sendBytes("hello", 5);
+	assertTrue (n == 5);
+	char buffer[256];
+	n = ss.receiveBytes(buffer, sizeof(buffer));
+	assertTrue (n == 5);
+	assertTrue (std::string(buffer, n) == "hello");
+	ss.close();
+}
+
 
 void SocketTest::onReadable(bool& b)
 {
@@ -650,6 +695,7 @@ CppUnit::Test* SocketTest::suite()
 	CppUnit_addTest(pSuite, SocketTest, testSelect3);
 	CppUnit_addTest(pSuite, SocketTest, testEchoUnixLocal);
 	CppUnit_addTest(pSuite, SocketTest, testUnixLocalAbstract);
+	CppUnit_addTest(pSuite, SocketTest, testUseFd);
 
 	return pSuite;
 }

Net/testsuite/src/SocketTest.h

@@ -43,6 +43,7 @@ class SocketTest: public CppUnit::TestCase
 	void testSelect3();
 	void testEchoUnixLocal();
 	void testUnixLocalAbstract();
+	void testUseFd();
 
 	void setUp();
 	void tearDown();