ipc: deduplicate some unix-specific code

Cleans up and splits out UAPIOpen to its own file.

Signed-off-by: David Crawshaw <crawshaw@tailscale.com>
[zx2c4: changed const to var for socketDirectory]
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

3 files changed, 65 insertions, 141 deletions

diff --git a/ipc/uapi_bsd.go b/ipc/uapi_bsd.go
index a74a7ed..d552a5e 100644
--- a/ipc/uapi_bsd.go
+++ b/ipc/uapi_bsd.go
@@ -9,25 +9,13 @@ package ipc
 
 import (
 	"errors"
-	"fmt"
 	"net"
 	"os"
-	"path"
 	"unsafe"
 
 	"golang.org/x/sys/unix"
 )
 
-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
@@ -84,10 +72,7 @@ func UAPIListen(name string, file *os.File) (net.Listener, error) {
 		unixListener.SetUnlinkOnClose(true)
 	}
 
-	socketPath := path.Join(
-		socketDirectory,
-		fmt.Sprintf(socketName, name),
-	)
+	socketPath := sockPath(name)
 
 	// watch for deletion of socket
 
@@ -146,57 +131,3 @@ func UAPIListen(name string, file *os.File) (net.Listener, error) {
 
 	return uapi, nil
 }
-
-func UAPIOpen(name string) (*os.File, error) {
-
-	// check if path exist
-
-	if err := os.MkdirAll(socketDirectory, 0755); err != nil {
-		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()
-}
diff --git a/ipc/uapi_linux.go b/ipc/uapi_linux.go
index dce6a45..70d4d0c 100644
--- a/ipc/uapi_linux.go
+++ b/ipc/uapi_linux.go
@@ -6,26 +6,13 @@
 package ipc
 
 import (
-	"errors"
-	"fmt"
 	"net"
 	"os"
-	"path"
 
 	"golang.org/x/sys/unix"
 	"golang.zx2c4.com/wireguard/rwcancel"
 )
 
-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
@@ -84,10 +71,7 @@ func UAPIListen(name string, file *os.File) (net.Listener, error) {
 
 	// watch for deletion of socket
 
-	socketPath := path.Join(
-		socketDirectory,
-		fmt.Sprintf(socketName, name),
-	)
+	socketPath := sockPath(name)
 
 	uapi.inotifyFd, err = unix.InotifyInit()
 	if err != nil {
@@ -143,57 +127,3 @@ func UAPIListen(name string, file *os.File) (net.Listener, error) {
 
 	return uapi, nil
 }
-
-func UAPIOpen(name string) (*os.File, error) {
-
-	// check if path exist
-
-	if err := os.MkdirAll(socketDirectory, 0755); err != nil {
-		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()
-}
diff --git a/ipc/uapi_unix.go b/ipc/uapi_unix.go
new file mode 100644
index 0000000..a59c390
--- /dev/null
+++ b/ipc/uapi_unix.go
@@ -0,0 +1,63 @@
+// +build linux darwin freebsd openbsd
+
+/* SPDX-License-Identifier: MIT
+ *
+ * Copyright (C) 2017-2019 WireGuard LLC. All Rights Reserved.
+ */
+
+package ipc
+
+import (
+	"errors"
+	"fmt"
+	"net"
+	"os"
+
+	"golang.org/x/sys/unix"
+)
+
+const (
+	IpcErrorIO        = -int64(unix.EIO)
+	IpcErrorProtocol  = -int64(unix.EPROTO)
+	IpcErrorInvalid   = -int64(unix.EINVAL)
+	IpcErrorPortInUse = -int64(unix.EADDRINUSE)
+)
+
+var socketDirectory = "/var/run/wireguard"
+
+func sockPath(iface string) string {
+	return fmt.Sprintf("%s/%s.sock", socketDirectory, iface)
+}
+
+func UAPIOpen(name string) (*os.File, error) {
+	if err := os.MkdirAll(socketDirectory, 0755); err != nil {
+		return nil, err
+	}
+
+	socketPath := sockPath(name)
+	addr, err := net.ResolveUnixAddr("unix", socketPath)
+	if err != nil {
+		return nil, err
+	}
+
+	oldUmask := unix.Umask(0077)
+	defer unix.Umask(oldUmask)
+
+	listener, err := net.ListenUnix("unix", addr)
+	if err == nil {
+		return listener.File()
+	}
+
+	// Test socket, if not in use cleanup and try again.
+	if _, err := net.Dial("unix", socketPath); err == nil {
+		return nil, errors.New("unix socket in use")
+	}
+	if err := os.Remove(socketPath); err != nil {
+		return nil, err
+	}
+	listener, err = net.ListenUnix("unix", addr)
+	if err != nil {
+		return nil, err
+	}
+	return listener.File()
+}