socket fs: support non-blocking 'connect()'

Fixes #3113

repos/dde_linux/src/lib/vfs/lxip/vfs.cc

@@ -635,7 +635,24 @@ class Vfs::Lxip_connect_file : public Vfs::Lxip_file
 		 ** File interface **
 		 ********************/
 
-		bool poll(bool, Vfs::Vfs_handle::Context *) { return true; }
+		bool poll(bool trigger_io_response, Vfs::Vfs_handle::Context *context)
+		{
+			/*
+			 * The connect file is considered readable when the socket is
+			 * writeable (connected or error).
+			 */
+
+			using namespace Linux;
+
+			file f;
+			f.f_flags = 0;
+			if (_sock.ops->poll(&f, &_sock, nullptr) & (POLLOUT_SET)) {
+				if (trigger_io_response)
+					_parent.trigger_io_response(context);
+				return true;
+			}
+			return false;
+		}
 
 		Lxip::ssize_t write(Lxip_vfs_file_handle &handle,
 		                    char const *src, Genode::size_t len,
@@ -657,12 +674,12 @@ class Vfs::Lxip_connect_file : public Vfs::Lxip_file
 			addr->sin_addr.s_addr = get_addr(handle.content_buffer);
 			addr->sin_family      = AF_INET;
 
-			_write_err = _sock.ops->connect(&_sock, (sockaddr *)addr, sizeof(addr_storage), 0);
+			_write_err = _sock.ops->connect(&_sock, (sockaddr *)addr, sizeof(addr_storage), O_NONBLOCK);
 
 			switch (_write_err) {
 			case Lxip::Io_result::LINUX_EINPROGRESS:
 				_connecting = true;
-				return -1;
+				return len;
 
 			case Lxip::Io_result::LINUX_EALREADY:
 				return -1;
@@ -679,6 +696,7 @@ class Vfs::Lxip_connect_file : public Vfs::Lxip_file
 
 			default:
 				if (_write_err != 0) return -1;
+				_is_connected = true;
 				break;
 			}
 
@@ -691,6 +709,29 @@ class Vfs::Lxip_connect_file : public Vfs::Lxip_file
 
 			return len;
 		}
+
+		Lxip::ssize_t read(Lxip_vfs_file_handle &handle,
+		                   char *dst, Genode::size_t len,
+		                   file_size /* ignored */) override
+		{
+			int so_error = 0;
+			int opt_len = sizeof(so_error);
+			int res = sock_getsockopt(&_sock, SOL_SOCKET, SO_ERROR, (char*)&so_error, &opt_len);
+
+			if (res != 0) {
+				Genode::error("Vfs::Lxip_connect_file::read(): getsockopt() failed");
+				return -1;
+			}
+
+			switch (so_error) {
+			case 0:
+				return Genode::snprintf(dst, len, "connected");
+			case Linux::ECONNREFUSED:
+				return Genode::snprintf(dst, len, "connection refused");
+			default:
+				return Genode::snprintf(dst, len, "unknown error");
+			}
+		}
 };
 
 

repos/libports/src/lib/libc/socket_fs_plugin.cc

@@ -114,6 +114,8 @@ struct Socket_fs::Context : Libc::Plugin_context
 
 		enum Proto { TCP, UDP };
 
+		enum State { UNCONNECTED, ACCEPT_ONLY, CONNECTING, CONNECTED, CONNECT_ABORTED };
+
 		struct Inaccessible { }; /* exception */
 
 		Absolute_path const path {
@@ -141,7 +143,7 @@ struct Socket_fs::Context : Libc::Plugin_context
 
 		Proto const _proto;
 
-		bool _accept_only = false;
+		State _state { UNCONNECTED };
 
 		template <typename FUNC>
 		void _fd_apply(FUNC const &fn)
@@ -196,7 +198,7 @@ struct Socket_fs::Context : Libc::Plugin_context
 		}
 
 		int data_fd()    { return _fd_for_type(Fd::DATA,    O_RDWR); }
-		int connect_fd() { return _fd_for_type(Fd::CONNECT, O_WRONLY); }
+		int connect_fd() { return _fd_for_type(Fd::CONNECT, O_RDWR); }
 		int bind_fd()    { return _fd_for_type(Fd::BIND,    O_WRONLY); }
 		int listen_fd()  { return _fd_for_type(Fd::LISTEN,  O_WRONLY); }
 		int accept_fd()  { return _fd_for_type(Fd::ACCEPT,  O_RDONLY); }
@@ -204,16 +206,57 @@ struct Socket_fs::Context : Libc::Plugin_context
 		int remote_fd()  { return _fd_for_type(Fd::REMOTE,  O_RDWR); }
 
 		/* request the appropriate fd to ensure the file is open */
-		bool data_read_ready()   { data_fd();   return _fd_read_ready(Fd::DATA); }
-		bool accept_read_ready() { accept_fd(); return _fd_read_ready(Fd::ACCEPT); }
-		bool local_read_ready()  { local_fd();  return _fd_read_ready(Fd::LOCAL); }
-		bool remote_read_ready() { remote_fd(); return _fd_read_ready(Fd::REMOTE); }
+		bool connect_read_ready() { connect_fd(); return _fd_read_ready(Fd::CONNECT); }
+		bool data_read_ready()    { data_fd();    return _fd_read_ready(Fd::DATA); }
+		bool accept_read_ready()  { accept_fd();  return _fd_read_ready(Fd::ACCEPT); }
+		bool local_read_ready()   { local_fd();   return _fd_read_ready(Fd::LOCAL); }
+		bool remote_read_ready()  { remote_fd();  return _fd_read_ready(Fd::REMOTE); }
 
-		void accept_only() { _accept_only = true; }
+		void state(State state) { _state = state; }
+		State state() const     { return _state; }
 
 		bool read_ready()
 		{
-			return _accept_only ? accept_read_ready() : data_read_ready();
+			return (_state == ACCEPT_ONLY) ? accept_read_ready() : data_read_ready();
+		}
+
+		bool write_ready()
+		{
+			if (_state == CONNECTING)
+				return connect_read_ready();
+
+			/* XXX ask if "data" is writeable */
+			return true;
+		}
+
+		/*
+		 * Read the connect status from the connect file and return 0 if connected
+		 * or -1 with errno set to the error code.
+		 */
+		int read_connect_status()
+		{
+			char connect_status[32] = { 0 };
+			ssize_t connect_status_len;
+
+			connect_status_len = read(connect_fd(), connect_status,
+									  sizeof(connect_status));
+
+			if (connect_status_len <= 0) {
+				Genode::error("socket_fs: reading from the connect file failed");
+				return -1;
+			}
+
+			if (strcmp(connect_status, "connected") == 0)
+				return 0;
+
+			if (strcmp(connect_status, "connection refused") == 0)
+				return Errno(ECONNREFUSED);
+
+			if (strcmp(connect_status, "not connected") == 0)
+				return Errno(ENOTCONN);
+
+			Genode::error("socket_fs: unhandled connection state");
+			return Errno(ECONNREFUSED);
 		}
 };
 
@@ -566,23 +609,81 @@ extern "C" int socket_fs_connect(int libc_fd, sockaddr const *addr, socklen_t ad
 		return Errno(EAFNOSUPPORT);
 	}
 
-	/* TODO EISCONN */
-	/* TODO ECONNREFUSED */
-	/* TODO maybe EALREADY, EINPROGRESS, ETIMEDOUT */
+	switch (context->state()) {
+	case Context::UNCONNECTED:
+		{
+			Sockaddr_string addr_string;
+			try {
+				addr_string = Sockaddr_string(host_string(*(sockaddr_in const *)addr),
+				                              port_string(*(sockaddr_in const *)addr));
+			}
+			catch (Address_conversion_failed) { return Errno(EINVAL); }
 
-	Sockaddr_string addr_string;
-	try {
-		addr_string = Sockaddr_string(host_string(*(sockaddr_in const *)addr),
-		                              port_string(*(sockaddr_in const *)addr));
+			context->state(Context::CONNECTING);
+
+			int const len = strlen(addr_string.base());
+			int const n   = write(context->connect_fd(), addr_string.base(), len);
+
+			if (n != len) return Errno(ECONNREFUSED);
+
+			if (context->fd_flags() & O_NONBLOCK)
+				return Errno(EINPROGRESS);
+
+			/* block until socket is ready for writing */
+
+			fd_set writefds;
+			FD_ZERO(&writefds);
+			FD_SET(libc_fd, &writefds);
+
+			enum { CONNECT_TIMEOUT_S = 10 };
+			struct timeval timeout {CONNECT_TIMEOUT_S, 0};
+			int res = select(libc_fd + 1, NULL, &writefds, NULL, &timeout);
+
+			if (res < 0) {
+				/* errno has been set by select() */
+				return res;
+			}
+
+			if (res == 0) {
+				context->state(Context::CONNECT_ABORTED);
+				return Errno(ETIMEDOUT);
+			}
+
+			int connect_status = context->read_connect_status();
+
+			if (connect_status == 0)
+				context->state(Context::CONNECTED);
+			else
+				context->state(Context::CONNECT_ABORTED);
+
+			/* errno has been set by context->read_connect_status() */
+			return connect_status;
+		}
+		break;
+	case Context::ACCEPT_ONLY:
+		return Errno(EINVAL);
+	case Context::CONNECTING:
+		{
+			if (!context->connect_read_ready())
+				return Errno(EALREADY);
+
+			int connect_status = context->read_connect_status();
+
+			if (connect_status == 0)
+				context->state(Context::CONNECTED);
+			else
+				context->state(Context::CONNECT_ABORTED);
+
+			/* errno was set by context->read_connect_status() */
+			return connect_status;
+		}
+	case Context::CONNECTED:
+		return Errno(EISCONN);
+	case Context::CONNECT_ABORTED:
+		return Errno(ECONNABORTED);
 	}
-	catch (Address_conversion_failed) { return Errno(EINVAL); }
 
-	int const len = strlen(addr_string.base());
-	int const n   = write(context->connect_fd(), addr_string.base(), len);
-	if (n != len) return Errno(ECONNREFUSED);
-
-	/* sync to block for write completion */
-	return fsync(context->connect_fd());
+	return Errno(ECONNREFUSED);
 }
 
 
@@ -599,7 +700,7 @@ extern "C" int socket_fs_listen(int libc_fd, int backlog)
 	int const n   = write(context->listen_fd(), buf, len);
 	if (n != len) return Errno(EOPNOTSUPP);
 
-	context->accept_only();
+	context->state(Context::ACCEPT_ONLY);
 	return 0;
 }
 
@@ -732,6 +833,21 @@ extern "C" int socket_fs_getsockopt(int libc_fd, int level, int optname,
 			*(int *)optval = 1;
 			return 0;
 		case SO_ERROR:
+			if (context->state() == Context::CONNECTING) {
+
+				int connect_status = context->read_connect_status();
+
+				if (connect_status == 0) {
+					*(int*)optval = 0;
+					context->state(Context::CONNECTED);
+				} else {
+					*(int*)optval = errno;
+					context->state(Context::CONNECT_ABORTED);
+				}
+
+				return 0;
+			}
+
 			/* not yet implemented - but return true */
 			*(int *)optval = 0;
 			return 0;
@@ -948,10 +1064,14 @@ int Socket_fs::Plugin::select(int nfds,
 		}
 
 		if (FD_ISSET(fd, &in_writefds)) {
-			if (true /* XXX ask if "data" is writeable */) {
-				FD_SET(fd, writefds);
-				++nready;
-			}
+			try {
+				Socket_fs::Context *context = dynamic_cast<Socket_fs::Context *>(fdo->context);
+
+				if (context->write_ready()) {
+					FD_SET(fd, writefds);
+					++nready;
+				}
+			} catch (Socket_fs::Context::Inaccessible) { }
 		}
 
 		/* XXX exceptfds not supported */

repos/libports/src/lib/vfs/lwip/vfs.cc

@@ -827,9 +827,11 @@ class Lwip::Udp_socket_dir final :
 
 			case Lwip_file_handle::CONNECT: {
 				/* check if the PCB was connected */
-				if (ip_addr_isany(&_pcb->remote_ip))
-					return Read_result::READ_OK;
-				/* otherwise fallthru to REMOTE*/
+				if (!ip_addr_isany(&_pcb->remote_ip))
+					out_count = Genode::snprintf(dst, count, "connected");
+				else
+					out_count = Genode::snprintf(dst, count, "not connected");
+				return Read_result::READ_OK;
 			}
 
 			case Lwip_file_handle::REMOTE: {
@@ -1162,7 +1164,11 @@ class Lwip::Tcp_socket_dir final :
 				break;
 
 			case Lwip_file_handle::CONNECT:
-				return !ip_addr_isany(&_pcb->remote_ip);
+				/*
+				 * The connect file is considered readable when the socket is
+				 * writeable (connected or error).
+				 */
+				return ((state == READY) || (state == CLOSED));
 
 			case Lwip_file_handle::LOCATION:
 			case Lwip_file_handle::LOCAL:
@@ -1303,6 +1309,15 @@ class Lwip::Tcp_socket_dir final :
 				break;
 
 			case Lwip_file_handle::CONNECT:
+				switch (state) {
+				case READY:
+					out_count = Genode::snprintf(dst, count, "connected");
+					break;
+				default:
+					out_count = Genode::snprintf(dst, count, "connection refused");
+					break;
+				}
+				return Read_result::READ_OK;
 			case Lwip_file_handle::LISTEN:
 			case Lwip_file_handle::INVALID: break;
 			}