Move dialer to pkg

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

pkg/dialer/dialer_unix.go

@@ -0,0 +1,52 @@
+// +build !windows
+
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package dialer
+
+import (
+	"fmt"
+	"net"
+	"os"
+	"strings"
+	"syscall"
+	"time"
+)
+
+// DialAddress returns the address with unix:// prepended to the
+// provided address
+func DialAddress(address string) string {
+	return fmt.Sprintf("unix://%s", address)
+}
+
+func isNoent(err error) bool {
+	if err != nil {
+		if nerr, ok := err.(*net.OpError); ok {
+			if serr, ok := nerr.Err.(*os.SyscallError); ok {
+				if serr.Err == syscall.ENOENT {
+					return true
+				}
+			}
+		}
+	}
+	return false
+}
+
+func dialer(address string, timeout time.Duration) (net.Conn, error) {
+	address = strings.TrimPrefix(address, "unix://")
+	return net.DialTimeout("unix", address, timeout)
+}