clientconn: add support for unix network in DialContext. (#1883)

clientconn.go

@@ -443,7 +443,8 @@ func DialContext(ctx context.Context, target string, opts ...DialOption) (conn *
 	if cc.dopts.copts.Dialer == nil {
 		cc.dopts.copts.Dialer = newProxyDialer(
 			func(ctx context.Context, addr string) (net.Conn, error) {
-				return dialContext(ctx, "tcp", addr)
+				network, addr := parseDialTarget(addr)
+				return dialContext(ctx, network, addr)
 			},
 		)
 	}

rpc_util.go

@@ -26,6 +26,7 @@ import (
 	"io"
 	"io/ioutil"
 	"math"
+	"net/url"
 	"strings"
 	"sync"
 	"time"
@@ -672,6 +673,40 @@ func setCallInfoCodec(c *callInfo) error {
 	return nil
 }
 
+// parseDialTarget returns the network and address to pass to dialer
+func parseDialTarget(target string) (net string, addr string) {
+	net = "tcp"
+
+	m1 := strings.Index(target, ":")
+	m2 := strings.Index(target, ":/")
+
+	// handle unix:addr which will fail with url.Parse
+	if m1 >= 0 && m2 < 0 {
+		if n := target[0:m1]; n == "unix" {
+			net = n
+			addr = target[m1+1:]
+			return net, addr
+		}
+	}
+	if m2 >= 0 {
+		t, err := url.Parse(target)
+		if err != nil {
+			return net, target
+		}
+		scheme := t.Scheme
+		addr = t.Path
+		if scheme == "unix" {
+			net = scheme
+			if addr == "" {
+				addr = t.Host
+			}
+			return net, addr
+		}
+	}
+
+	return net, target
+}
+
 // The SupportPackageIsVersion variables are referenced from generated protocol
 // buffer files to ensure compatibility with the gRPC version used.  The latest
 // support package version is 5.

rpc_util_test.go

@@ -188,6 +188,27 @@ func TestToRPCErr(t *testing.T) {
 	}
 }
 
+func TestParseDialTarget(t *testing.T) {
+	for _, test := range []struct {
+		target, wantNet, wantAddr string
+	}{
+		{"unix:etcd:0", "unix", "etcd:0"},
+		{"unix:///tmp/unix-3", "unix", "/tmp/unix-3"},
+		{"unix://domain", "unix", "domain"},
+		{"unix://etcd:0", "unix", "etcd:0"},
+		{"unix:///etcd:0", "unix", "/etcd:0"},
+		{"passthrough://unix://domain", "tcp", "passthrough://unix://domain"},
+		{"https://google.com:443", "tcp", "https://google.com:443"},
+		{"dns:///google.com", "tcp", "dns:///google.com"},
+		{"/unix/socket/address", "tcp", "/unix/socket/address"},
+	} {
+		gotNet, gotAddr := parseDialTarget(test.target)
+		if gotNet != test.wantNet || gotAddr != test.wantAddr {
+			t.Errorf("parseDialTarget(%q) = %s, %s want %s, %s", test.target, gotNet, gotAddr, test.wantNet, test.wantAddr)
+		}
+	}
+}
+
 // bmEncode benchmarks encoding a Protocol Buffer message containing mSize
 // bytes.
 func bmEncode(b *testing.B, mSize int) {