update vendor

vendor/github.com/docker/go-connections/sockets/sockets.go

@@ -0,0 +1,42 @@
+// Package sockets provides helper functions to create and configure Unix or TCP sockets.
+package sockets
+
+import (
+	"net"
+	"net/http"
+	"time"
+)
+
+// Why 32? See https://github.com/docker/docker/pull/8035.
+const defaultTimeout = 32 * time.Second
+
+// ConfigureTransport configures the specified Transport according to the
+// specified proto and addr.
+// If the proto is unix (using a unix socket to communicate) or npipe the
+// compression is disabled.
+func ConfigureTransport(tr *http.Transport, proto, addr string) error {
+	switch proto {
+	case "unix":
+		// No need for compression in local communications.
+		tr.DisableCompression = true
+		tr.Dial = func(_, _ string) (net.Conn, error) {
+			return net.DialTimeout(proto, addr, defaultTimeout)
+		}
+	case "npipe":
+		// No need for compression in local communications.
+		tr.DisableCompression = true
+		tr.Dial = func(_, _ string) (net.Conn, error) {
+			return DialPipe(addr, defaultTimeout)
+		}
+	default:
+		tr.Proxy = http.ProxyFromEnvironment
+		dialer, err := DialerFromEnvironment(&net.Dialer{
+			Timeout: defaultTimeout,
+		})
+		if err != nil {
+			return err
+		}
+		tr.Dial = dialer.Dial
+	}
+	return nil
+}