net: fix parsing literal IPv6 address with zone identifier when using cgo

Parsing literal IPv6 address with zone identifier is already supported
when not using cgo. This change enables it when using cgo too.

Fixes #12241.

Change-Id: I3ed78c9e750e75eff0dae76ba8608df39503cf85
Reviewed-on: https://go-review.googlesource.com/17215
Run-TryBot: Mikio Hara <mikioh.mikioh@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

src/net/cgo_socknew.go

@@ -26,8 +26,8 @@ func cgoSockaddrInet4(ip IP) *C.struct_sockaddr {
 	return (*C.struct_sockaddr)(unsafe.Pointer(&sa))
 }
 
-func cgoSockaddrInet6(ip IP) *C.struct_sockaddr {
+func cgoSockaddrInet6(ip IP, zone int) *C.struct_sockaddr {
-	sa := syscall.RawSockaddrInet6{Family: syscall.AF_INET6}
+	sa := syscall.RawSockaddrInet6{Family: syscall.AF_INET6, Scope_id: uint32(zone)}
 	copy(sa.Addr[:], ip)
 	return (*C.struct_sockaddr)(unsafe.Pointer(&sa))
 }

src/net/cgo_sockold.go

@@ -26,8 +26,8 @@ func cgoSockaddrInet4(ip IP) *C.struct_sockaddr {
 	return (*C.struct_sockaddr)(unsafe.Pointer(&sa))
 }
 
-func cgoSockaddrInet6(ip IP) *C.struct_sockaddr {
+func cgoSockaddrInet6(ip IP, zone int) *C.struct_sockaddr {
-	sa := syscall.RawSockaddrInet6{Len: syscall.SizeofSockaddrInet6, Family: syscall.AF_INET6}
+	sa := syscall.RawSockaddrInet6{Len: syscall.SizeofSockaddrInet6, Family: syscall.AF_INET6, Scope_id: uint32(zone)}
 	copy(sa.Addr[:], ip)
 	return (*C.struct_sockaddr)(unsafe.Pointer(&sa))
 }

src/net/cgo_unix.go

@@ -186,11 +186,15 @@ func cgoLookupPTR(addr string) ([]string, error, bool) {
 	acquireThread()
 	defer releaseThread()
 
-	ip := ParseIP(addr)
+	var zone string
+	ip := parseIPv4(addr)
+	if ip == nil {
+		ip, zone = parseIPv6(addr, true)
+	}
 	if ip == nil {
 		return nil, &DNSError{Err: "invalid address", Name: addr}, true
 	}
-	sa, salen := cgoSockaddr(ip)
+	sa, salen := cgoSockaddr(ip, zone)
 	if sa == nil {
 		return nil, &DNSError{Err: "invalid address " + ip.String(), Name: addr}, true
 	}
@@ -225,12 +229,12 @@ func cgoLookupPTR(addr string) ([]string, error, bool) {
 	return []string{absDomainName(b)}, nil, true
 }
 
-func cgoSockaddr(ip IP) (*C.struct_sockaddr, C.socklen_t) {
+func cgoSockaddr(ip IP, zone string) (*C.struct_sockaddr, C.socklen_t) {
 	if ip4 := ip.To4(); ip4 != nil {
 		return cgoSockaddrInet4(ip4), C.socklen_t(syscall.SizeofSockaddrInet4)
 	}
 	if ip6 := ip.To16(); ip6 != nil {
-		return cgoSockaddrInet6(ip6), C.socklen_t(syscall.SizeofSockaddrInet6)
+		return cgoSockaddrInet6(ip6, zoneToInt(zone)), C.socklen_t(syscall.SizeofSockaddrInet6)
 	}
 	return nil, 0
 }

src/net/lookup_test.go

@@ -209,6 +209,30 @@ func TestLookupGooglePublicDNSAddr(t *testing.T) {
 	}
 }
 
+func TestLookupIPv6LinkLocalAddr(t *testing.T) {
+	if !supportsIPv6 {
+		t.Skip("IPv6 is required")
+	}
+
+	addrs, err := LookupHost("localhost")
+	if err != nil {
+		t.Fatal(err)
+	}
+	found := false
+	for _, addr := range addrs {
+		if addr == "fe80::1%lo0" {
+			found = true
+			break
+		}
+	}
+	if !found {
+		t.Skipf("not supported on %s", runtime.GOOS)
+	}
+	if _, err := LookupAddr("fe80::1%lo0"); err != nil {
+		t.Error(err)
+	}
+}
+
 var lookupIANACNAMETests = []struct {
 	name, cname string
 }{

src/net/testdata/hosts

@@ -5,8 +5,7 @@
 127.1.1.1	thor
 # aliases
 127.1.1.2	ullr ullrhost
+fe80::1%lo0	localhost
 # Bogus entries that must be ignored.
 123.123.123	loki
 321.321.321.321
-# TODO(yvesj): Should we be able to parse this? From a Darwin system.
-fe80::1%lo0	localhost