global: begin modularization

ipc/uapi_linux.go

@@ -0,0 +1,199 @@
+/* SPDX-License-Identifier: MIT
+ *
+ * Copyright (C) 2017-2019 WireGuard LLC. All Rights Reserved.
+ */
+
+package ipc
+
+import (
+	"errors"
+	"fmt"
+	"golang.org/x/sys/unix"
+	"golang.zx2c4.com/wireguard/rwcancel"
+	"net"
+	"os"
+	"path"
+)
+
+var socketDirectory = "/var/run/wireguard"
+
+const (
+	IpcErrorIO        = -int64(unix.EIO)
+	IpcErrorProtocol  = -int64(unix.EPROTO)
+	IpcErrorInvalid   = -int64(unix.EINVAL)
+	IpcErrorPortInUse = -int64(unix.EADDRINUSE)
+	socketName        = "%s.sock"
+)
+
+type UAPIListener struct {
+	listener        net.Listener // unix socket listener
+	connNew         chan net.Conn
+	connErr         chan error
+	inotifyFd       int
+	inotifyRWCancel *rwcancel.RWCancel
+}
+
+func (l *UAPIListener) Accept() (net.Conn, error) {
+	for {
+		select {
+		case conn := <-l.connNew:
+			return conn, nil
+
+		case err := <-l.connErr:
+			return nil, err
+		}
+	}
+}
+
+func (l *UAPIListener) Close() error {
+	err1 := unix.Close(l.inotifyFd)
+	err2 := l.inotifyRWCancel.Cancel()
+	err3 := l.listener.Close()
+	if err1 != nil {
+		return err1
+	}
+	if err2 != nil {
+		return err2
+	}
+	return err3
+}
+
+func (l *UAPIListener) Addr() net.Addr {
+	return l.listener.Addr()
+}
+
+func UAPIListen(name string, file *os.File) (net.Listener, error) {
+
+	// wrap file in listener
+
+	listener, err := net.FileListener(file)
+	if err != nil {
+		return nil, err
+	}
+
+	if unixListener, ok := listener.(*net.UnixListener); ok {
+		unixListener.SetUnlinkOnClose(true)
+	}
+
+	uapi := &UAPIListener{
+		listener: listener,
+		connNew:  make(chan net.Conn, 1),
+		connErr:  make(chan error, 1),
+	}
+
+	// watch for deletion of socket
+
+	socketPath := path.Join(
+		socketDirectory,
+		fmt.Sprintf(socketName, name),
+	)
+
+	uapi.inotifyFd, err = unix.InotifyInit()
+	if err != nil {
+		return nil, err
+	}
+
+	_, err = unix.InotifyAddWatch(
+		uapi.inotifyFd,
+		socketPath,
+		unix.IN_ATTRIB|
+			unix.IN_DELETE|
+			unix.IN_DELETE_SELF,
+	)
+
+	if err != nil {
+		return nil, err
+	}
+
+	uapi.inotifyRWCancel, err = rwcancel.NewRWCancel(uapi.inotifyFd)
+	if err != nil {
+		unix.Close(uapi.inotifyFd)
+		return nil, err
+	}
+
+	go func(l *UAPIListener) {
+		var buff [0]byte
+		for {
+			// start with lstat to avoid race condition
+			if _, err := os.Lstat(socketPath); os.IsNotExist(err) {
+				l.connErr <- err
+				return
+			}
+			_, err := uapi.inotifyRWCancel.Read(buff[:])
+			if err != nil {
+				l.connErr <- err
+				return
+			}
+		}
+	}(uapi)
+
+	// watch for new connections
+
+	go func(l *UAPIListener) {
+		for {
+			conn, err := l.listener.Accept()
+			if err != nil {
+				l.connErr <- err
+				break
+			}
+			l.connNew <- conn
+		}
+	}(uapi)
+
+	return uapi, nil
+}
+
+func UAPIOpen(name string) (*os.File, error) {
+
+	// check if path exist
+
+	err := os.MkdirAll(socketDirectory, 0755)
+	if err != nil && !os.IsExist(err) {
+		return nil, err
+	}
+
+	// open UNIX socket
+
+	socketPath := path.Join(
+		socketDirectory,
+		fmt.Sprintf(socketName, name),
+	)
+
+	addr, err := net.ResolveUnixAddr("unix", socketPath)
+	if err != nil {
+		return nil, err
+	}
+
+	oldUmask := unix.Umask(0077)
+	listener, err := func() (*net.UnixListener, error) {
+
+		// initial connection attempt
+
+		listener, err := net.ListenUnix("unix", addr)
+		if err == nil {
+			return listener, nil
+		}
+
+		// check if socket already active
+
+		_, err = net.Dial("unix", socketPath)
+		if err == nil {
+			return nil, errors.New("unix socket in use")
+		}
+
+		// cleanup & attempt again
+
+		err = os.Remove(socketPath)
+		if err != nil {
+			return nil, err
+		}
+		return net.ListenUnix("unix", addr)
+	}()
+	unix.Umask(oldUmask)
+
+	if err != nil {
+		return nil, err
+	}
+
+	return listener.File()
+}