net: make raw IP tests robust

Make it rely on underlying socket's address family.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/5673091

src/pkg/net/ipraw_test.go

@@ -7,6 +7,7 @@ package net
 import (
 	"bytes"
 	"os"
+	"syscall"
 	"testing"
 	"time"
 )
@@ -15,7 +16,7 @@ var icmpTests = []struct {
 	net   string
 	laddr string
 	raddr string
-	ipv6  bool
+	ipv6  bool // test with underlying AF_INET6 socket
 }{
 	{"ip4:icmp", "", "127.0.0.1", false},
 	{"ip6:icmp", "", "::1", true},
@@ -34,15 +35,15 @@ func TestICMP(t *testing.T) {
 		}
 		id := os.Getpid() & 0xffff
 		seqnum++
-		echo := newICMPEchoRequest(tt.ipv6, id, seqnum, 128, []byte("Go Go Gadget Ping!!!"))
-		exchangeICMPEcho(t, tt.net, tt.laddr, tt.raddr, tt.ipv6, echo)
+		echo := newICMPEchoRequest(tt.net, id, seqnum, 128, []byte("Go Go Gadget Ping!!!"))
+		exchangeICMPEcho(t, tt.net, tt.laddr, tt.raddr, echo)
 	}
 }
 
-func exchangeICMPEcho(t *testing.T, net, laddr, raddr string, ipv6 bool, echo []byte) {
+func exchangeICMPEcho(t *testing.T, net, laddr, raddr string, echo []byte) {
 	c, err := ListenPacket(net, laddr)
 	if err != nil {
-		t.Errorf("ListenPacket(%#q, %#q) failed: %v", net, laddr, err)
+		t.Errorf("ListenPacket(%q, %q) failed: %v", net, laddr, err)
 		return
 	}
 	c.SetDeadline(time.Now().Add(100 * time.Millisecond))
@@ -50,12 +51,12 @@ func exchangeICMPEcho(t *testing.T, net, laddr, raddr string, ipv6 bool, echo []
 
 	ra, err := ResolveIPAddr(net, raddr)
 	if err != nil {
-		t.Errorf("ResolveIPAddr(%#q, %#q) failed: %v", net, raddr, err)
+		t.Errorf("ResolveIPAddr(%q, %q) failed: %v", net, raddr, err)
 		return
 	}
 
 	waitForReady := make(chan bool)
-	go icmpEchoTransponder(t, net, raddr, ipv6, waitForReady)
+	go icmpEchoTransponder(t, net, raddr, waitForReady)
 	<-waitForReady
 
 	_, err = c.WriteTo(echo, ra)
@@ -71,11 +72,15 @@ func exchangeICMPEcho(t *testing.T, net, laddr, raddr string, ipv6 bool, echo []
 			t.Errorf("ReadFrom failed: %v", err)
 			return
 		}
-		if !ipv6 && reply[0] != ICMP4_ECHO_REPLY {
-			continue
-		}
-		if ipv6 && reply[0] != ICMP6_ECHO_REPLY {
-			continue
+		switch c.(*IPConn).fd.family {
+		case syscall.AF_INET:
+			if reply[0] != ICMP4_ECHO_REPLY {
+				continue
+			}
+		case syscall.AF_INET6:
+			if reply[0] != ICMP6_ECHO_REPLY {
+				continue
+			}
 		}
 		xid, xseqnum := parseICMPEchoReply(echo)
 		rid, rseqnum := parseICMPEchoReply(reply)
@@ -87,11 +92,11 @@ func exchangeICMPEcho(t *testing.T, net, laddr, raddr string, ipv6 bool, echo []
 	}
 }
 
-func icmpEchoTransponder(t *testing.T, net, raddr string, ipv6 bool, waitForReady chan bool) {
+func icmpEchoTransponder(t *testing.T, net, raddr string, waitForReady chan bool) {
 	c, err := Dial(net, raddr)
 	if err != nil {
 		waitForReady <- true
-		t.Errorf("Dial(%#q, %#q) failed: %v", net, raddr, err)
+		t.Errorf("Dial(%q, %q) failed: %v", net, raddr, err)
 		return
 	}
 	c.SetDeadline(time.Now().Add(100 * time.Millisecond))
@@ -106,18 +111,23 @@ func icmpEchoTransponder(t *testing.T, net, raddr string, ipv6 bool, waitForRead
 			t.Errorf("Read failed: %v", err)
 			return
 		}
-		if !ipv6 && echo[0] != ICMP4_ECHO_REQUEST {
-			continue
-		}
-		if ipv6 && echo[0] != ICMP6_ECHO_REQUEST {
-			continue
+		switch c.(*IPConn).fd.family {
+		case syscall.AF_INET:
+			if echo[0] != ICMP4_ECHO_REQUEST {
+				continue
+			}
+		case syscall.AF_INET6:
+			if echo[0] != ICMP6_ECHO_REQUEST {
+				continue
+			}
 		}
 		break
 	}
 
-	if !ipv6 {
+	switch c.(*IPConn).fd.family {
+	case syscall.AF_INET:
 		echo[0] = ICMP4_ECHO_REPLY
-	} else {
+	case syscall.AF_INET6:
 		echo[0] = ICMP6_ECHO_REPLY
 	}
 
@@ -135,11 +145,15 @@ const (
 	ICMP6_ECHO_REPLY   = 129
 )
 
-func newICMPEchoRequest(ipv6 bool, id, seqnum, msglen int, filler []byte) []byte {
-	if !ipv6 {
+func newICMPEchoRequest(net string, id, seqnum, msglen int, filler []byte) []byte {
+	afnet, _, _ := parseDialNetwork(net)
+	switch afnet {
+	case "ip4":
 		return newICMPv4EchoRequest(id, seqnum, msglen, filler)
+	case "ip6":
+		return newICMPv6EchoRequest(id, seqnum, msglen, filler)
 	}
-	return newICMPv6EchoRequest(id, seqnum, msglen, filler)
+	return nil
 }
 
 func newICMPv4EchoRequest(id, seqnum, msglen int, filler []byte) []byte {