Move dial funcs to dialer pkg

This reduces shim size from 30mb to 18mb

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

dialer/dialer.go

@@ -0,0 +1,58 @@
+package dialer
+
+import (
+	"fmt"
+	"net"
+	"time"
+
+	"github.com/pkg/errors"
+)
+
+type dialResult struct {
+	c   net.Conn
+	err error
+}
+
+// DialAddress returns the address with unix:// prepended to the
+// provided address
+func DialAddress(address string) string {
+	return fmt.Sprintf("unix://%s", address)
+}
+
+// Dialer returns a GRPC net.Conn connected to the provided address
+func Dialer(address string, timeout time.Duration) (net.Conn, error) {
+	var (
+		stopC = make(chan struct{})
+		synC  = make(chan *dialResult)
+	)
+	go func() {
+		defer close(synC)
+		for {
+			select {
+			case <-stopC:
+				return
+			default:
+				c, err := dialer(address, timeout)
+				if isNoent(err) {
+					<-time.After(10 * time.Millisecond)
+					continue
+				}
+				synC <- &dialResult{c, err}
+				return
+			}
+		}
+	}()
+	select {
+	case dr := <-synC:
+		return dr.c, dr.err
+	case <-time.After(timeout):
+		close(stopC)
+		go func() {
+			dr := <-synC
+			if dr != nil {
+				dr.c.Close()
+			}
+		}()
+		return nil, errors.Errorf("dial %s: timeout", address)
+	}
+}

dialer/dialer_unix.go

@@ -0,0 +1,29 @@
+// +build !windows
+
+package dialer
+
+import (
+	"net"
+	"os"
+	"strings"
+	"syscall"
+	"time"
+)
+
+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)
+}

dialer/dialer_windows.go

@@ -0,0 +1,30 @@
+package dialer
+
+import (
+	"net"
+	"os"
+	"syscall"
+	"time"
+
+	winio "github.com/Microsoft/go-winio"
+)
+
+func isNoent(err error) bool {
+	if err != nil {
+		if oerr, ok := err.(*os.PathError); ok {
+			if oerr.Err == syscall.ENOENT {
+				return true
+			}
+		}
+	}
+	return false
+}
+
+func dialer(address string, timeout time.Duration) (net.Conn, error) {
+	return winio.DialPipe(address, &timeout)
+}
+
+// DialAddress returns the dial address
+func DialAddress(address string) string {
+	return address
+}