net: filter destination addresses when source address is specified

This change filters out destination addresses by address family when
source address is specified to avoid running Dial operation with wrong
addressing scopes.

Fixes #11837.

Change-Id: I10b7a1fa325add2cd8ed58f105d527700a10d342
Reviewed-on: https://go-review.googlesource.com/20586
Reviewed-by: Paul Marks <pmarks@google.com>

src/net/dial.go

@@ -5,7 +5,6 @@
 package net
 
 import (
-	"errors"
 	"runtime"
 	"time"
 )
@@ -140,8 +139,11 @@ func parseNetwork(net string) (afnet string, proto int, err error) {
 	return "", 0, UnknownNetworkError(net)
 }
 
-func resolveAddrList(op, net, addr string, deadline time.Time) (addrList, error) {
-	afnet, _, err := parseNetwork(net)
+// resolverAddrList resolves addr using hint and returns a list of
+// addresses. The result contains at least one address when error is
+// nil.
+func resolveAddrList(op, network, addr string, hint Addr, deadline time.Time) (addrList, error) {
+	afnet, _, err := parseNetwork(network)
 	if err != nil {
 		return nil, err
 	}
@@ -154,9 +156,59 @@ func resolveAddrList(op, net, addr string, deadline time.Time) (addrList, error)
 		if err != nil {
 			return nil, err
 		}
+		if op == "dial" && hint != nil && addr.Network() != hint.Network() {
+			return nil, &AddrError{Err: "mismatched local address type", Addr: hint.String()}
+		}
 		return addrList{addr}, nil
 	}
-	return internetAddrList(afnet, addr, deadline)
+	addrs, err := internetAddrList(afnet, addr, deadline)
+	if err != nil || op != "dial" || hint == nil {
+		return addrs, err
+	}
+	var (
+		tcp      *TCPAddr
+		udp      *UDPAddr
+		ip       *IPAddr
+		wildcard bool
+	)
+	switch hint := hint.(type) {
+	case *TCPAddr:
+		tcp = hint
+		wildcard = tcp.isWildcard()
+	case *UDPAddr:
+		udp = hint
+		wildcard = udp.isWildcard()
+	case *IPAddr:
+		ip = hint
+		wildcard = ip.isWildcard()
+	}
+	naddrs := addrs[:0]
+	for _, addr := range addrs {
+		if addr.Network() != hint.Network() {
+			return nil, &AddrError{Err: "mismatched local address type", Addr: hint.String()}
+		}
+		switch addr := addr.(type) {
+		case *TCPAddr:
+			if !wildcard && !addr.isWildcard() && !addr.IP.matchAddrFamily(tcp.IP) {
+				continue
+			}
+			naddrs = append(naddrs, addr)
+		case *UDPAddr:
+			if !wildcard && !addr.isWildcard() && !addr.IP.matchAddrFamily(udp.IP) {
+				continue
+			}
+			naddrs = append(naddrs, addr)
+		case *IPAddr:
+			if !wildcard && !addr.isWildcard() && !addr.IP.matchAddrFamily(ip.IP) {
+				continue
+			}
+			naddrs = append(naddrs, addr)
+		}
+	}
+	if len(naddrs) == 0 {
+		return nil, errNoSuitableAddress
+	}
+	return naddrs, nil
 }
 
 // Dial connects to the address on the named network.
@@ -214,7 +266,7 @@ type dialContext struct {
 // parameters.
 func (d *Dialer) Dial(network, address string) (Conn, error) {
 	finalDeadline := d.deadline(time.Now())
-	addrs, err := resolveAddrList("dial", network, address, finalDeadline)
+	addrs, err := resolveAddrList("dial", network, address, d.LocalAddr, finalDeadline)
 	if err != nil {
 		return nil, &OpError{Op: "dial", Net: network, Source: nil, Addr: nil, Err: err}
 	}
@@ -387,9 +439,6 @@ func dialSerial(ctx *dialContext, ras addrList, cancel <-chan struct{}) (Conn, e
 // dial function, because some OSes don't implement the deadline feature.
 func dialSingle(ctx *dialContext, ra Addr, deadline time.Time, cancel <-chan struct{}) (c Conn, err error) {
 	la := ctx.LocalAddr
-	if la != nil && la.Network() != ra.Network() {
-		return nil, &OpError{Op: "dial", Net: ctx.network, Source: la, Addr: ra, Err: errors.New("mismatched local address type " + la.Network())}
-	}
 	switch ra := ra.(type) {
 	case *TCPAddr:
 		la, _ := la.(*TCPAddr)
@@ -420,7 +469,7 @@ func dialSingle(ctx *dialContext, ra Addr, deadline time.Time, cancel <-chan str
 // instead of just the interface with the given host address.
 // See Dial for more details about address syntax.
 func Listen(net, laddr string) (Listener, error) {
-	addrs, err := resolveAddrList("listen", net, laddr, noDeadline)
+	addrs, err := resolveAddrList("listen", net, laddr, nil, noDeadline)
 	if err != nil {
 		return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: nil, Err: err}
 	}
@@ -447,7 +496,7 @@ func Listen(net, laddr string) (Listener, error) {
 // instead of just the interface with the given host address.
 // See Dial for the syntax of laddr.
 func ListenPacket(net, laddr string) (PacketConn, error) {
-	addrs, err := resolveAddrList("listen", net, laddr, noDeadline)
+	addrs, err := resolveAddrList("listen", net, laddr, nil, noDeadline)
 	if err != nil {
 		return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: nil, Err: err}
 	}

src/net/dial_test.go

@@ -646,41 +646,118 @@ func TestDialerPartialDeadline(t *testing.T) {
 	}
 }
 
+type dialerLocalAddrTest struct {
+	network, raddr string
+	laddr          Addr
+	error
+}
+
+var dialerLocalAddrTests = []dialerLocalAddrTest{
+	{"tcp4", "127.0.0.1", nil, nil},
+	{"tcp4", "127.0.0.1", &TCPAddr{}, nil},
+	{"tcp4", "127.0.0.1", &TCPAddr{IP: ParseIP("0.0.0.0")}, nil},
+	{"tcp4", "127.0.0.1", &TCPAddr{IP: ParseIP("0.0.0.0").To4()}, nil},
+	{"tcp4", "127.0.0.1", &TCPAddr{IP: ParseIP("::")}, &AddrError{Err: "some error"}},
+	{"tcp4", "127.0.0.1", &TCPAddr{IP: ParseIP("127.0.0.1").To4()}, nil},
+	{"tcp4", "127.0.0.1", &TCPAddr{IP: ParseIP("127.0.0.1").To16()}, nil},
+	{"tcp4", "127.0.0.1", &TCPAddr{IP: IPv6loopback}, errNoSuitableAddress},
+	{"tcp4", "127.0.0.1", &UDPAddr{}, &AddrError{Err: "some error"}},
+	{"tcp4", "127.0.0.1", &UnixAddr{}, &AddrError{Err: "some error"}},
+
+	{"tcp6", "::1", nil, nil},
+	{"tcp6", "::1", &TCPAddr{}, nil},
+	{"tcp6", "::1", &TCPAddr{IP: ParseIP("0.0.0.0")}, nil},
+	{"tcp6", "::1", &TCPAddr{IP: ParseIP("0.0.0.0").To4()}, nil},
+	{"tcp6", "::1", &TCPAddr{IP: ParseIP("::")}, nil},
+	{"tcp6", "::1", &TCPAddr{IP: ParseIP("127.0.0.1").To4()}, errNoSuitableAddress},
+	{"tcp6", "::1", &TCPAddr{IP: ParseIP("127.0.0.1").To16()}, errNoSuitableAddress},
+	{"tcp6", "::1", &TCPAddr{IP: IPv6loopback}, nil},
+	{"tcp6", "::1", &UDPAddr{}, &AddrError{Err: "some error"}},
+	{"tcp6", "::1", &UnixAddr{}, &AddrError{Err: "some error"}},
+
+	{"tcp", "127.0.0.1", nil, nil},
+	{"tcp", "127.0.0.1", &TCPAddr{}, nil},
+	{"tcp", "127.0.0.1", &TCPAddr{IP: ParseIP("0.0.0.0")}, nil},
+	{"tcp", "127.0.0.1", &TCPAddr{IP: ParseIP("0.0.0.0").To4()}, nil},
+	{"tcp", "127.0.0.1", &TCPAddr{IP: ParseIP("127.0.0.1").To4()}, nil},
+	{"tcp", "127.0.0.1", &TCPAddr{IP: ParseIP("127.0.0.1").To16()}, nil},
+	{"tcp", "127.0.0.1", &TCPAddr{IP: IPv6loopback}, errNoSuitableAddress},
+	{"tcp", "127.0.0.1", &UDPAddr{}, &AddrError{Err: "some error"}},
+	{"tcp", "127.0.0.1", &UnixAddr{}, &AddrError{Err: "some error"}},
+
+	{"tcp", "::1", nil, nil},
+	{"tcp", "::1", &TCPAddr{}, nil},
+	{"tcp", "::1", &TCPAddr{IP: ParseIP("0.0.0.0")}, nil},
+	{"tcp", "::1", &TCPAddr{IP: ParseIP("0.0.0.0").To4()}, nil},
+	{"tcp", "::1", &TCPAddr{IP: ParseIP("::")}, nil},
+	{"tcp", "::1", &TCPAddr{IP: ParseIP("127.0.0.1").To4()}, errNoSuitableAddress},
+	{"tcp", "::1", &TCPAddr{IP: ParseIP("127.0.0.1").To16()}, errNoSuitableAddress},
+	{"tcp", "::1", &TCPAddr{IP: IPv6loopback}, nil},
+	{"tcp", "::1", &UDPAddr{}, &AddrError{Err: "some error"}},
+	{"tcp", "::1", &UnixAddr{}, &AddrError{Err: "some error"}},
+}
+
 func TestDialerLocalAddr(t *testing.T) {
-	ch := make(chan error, 1)
-	handler := func(ls *localServer, ln Listener) {
-		c, err := ln.Accept()
-		if err != nil {
-			ch <- err
-			return
-		}
-		defer c.Close()
-		ch <- nil
-	}
-	ls, err := newLocalServer("tcp")
-	if err != nil {
-		t.Fatal(err)
-	}
-	defer ls.teardown()
-	if err := ls.buildup(handler); err != nil {
-		t.Fatal(err)
+	if !supportsIPv4 || !supportsIPv6 {
+		t.Skip("both IPv4 and IPv6 are required")
 	}
 
-	laddr, err := ResolveTCPAddr(ls.Listener.Addr().Network(), ls.Listener.Addr().String())
-	if err != nil {
-		t.Fatal(err)
+	if supportsIPv4map {
+		dialerLocalAddrTests = append(dialerLocalAddrTests, dialerLocalAddrTest{
+			"tcp", "127.0.0.1", &TCPAddr{IP: ParseIP("::")}, nil,
+		})
+	} else {
+		dialerLocalAddrTests = append(dialerLocalAddrTests, dialerLocalAddrTest{
+			"tcp", "127.0.0.1", &TCPAddr{IP: ParseIP("::")}, &AddrError{Err: "some error"},
+		})
 	}
-	laddr.Port = 0
-	d := &Dialer{LocalAddr: laddr}
-	c, err := d.Dial(ls.Listener.Addr().Network(), ls.Addr().String())
-	if err != nil {
-		t.Fatal(err)
+
+	origTestHookLookupIP := testHookLookupIP
+	defer func() { testHookLookupIP = origTestHookLookupIP }()
+	testHookLookupIP = lookupLocalhost
+	handler := func(ls *localServer, ln Listener) {
+		for {
+			c, err := ln.Accept()
+			if err != nil {
+				return
+			}
+			c.Close()
+		}
 	}
-	defer c.Close()
-	c.Read(make([]byte, 1))
-	err = <-ch
-	if err != nil {
-		t.Error(err)
+	var err error
+	var lss [2]*localServer
+	for i, network := range []string{"tcp4", "tcp6"} {
+		lss[i], err = newLocalServer(network)
+		if err != nil {
+			t.Fatal(err)
+		}
+		defer lss[i].teardown()
+		if err := lss[i].buildup(handler); err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	for _, tt := range dialerLocalAddrTests {
+		d := &Dialer{LocalAddr: tt.laddr}
+		var addr string
+		ip := ParseIP(tt.raddr)
+		if ip.To4() != nil {
+			addr = lss[0].Listener.Addr().String()
+		}
+		if ip.To16() != nil && ip.To4() == nil {
+			addr = lss[1].Listener.Addr().String()
+		}
+		c, err := d.Dial(tt.network, addr)
+		if err == nil && tt.error != nil || err != nil && tt.error == nil {
+			t.Errorf("%s %v->%s: got %v; want %v", tt.network, tt.laddr, tt.raddr, err, tt.error)
+		}
+		if err != nil {
+			if perr := parseDialError(err); perr != nil {
+				t.Error(perr)
+			}
+			continue
+		}
+		c.Close()
 	}
 }
 

src/net/error_test.go

@@ -96,7 +96,7 @@ second:
 		goto third
 	}
 	switch nestedErr {
-	case errCanceled, errClosing, errMissingAddress:
+	case errCanceled, errClosing, errMissingAddress, errNoSuitableAddress:
 		return nil
 	}
 	return fmt.Errorf("unexpected type on 2nd nested level: %T", nestedErr)
@@ -416,7 +416,7 @@ second:
 		goto third
 	}
 	switch nestedErr {
-	case errCanceled, errClosing, errTimeout, ErrWriteToConnected, io.ErrUnexpectedEOF:
+	case errCanceled, errClosing, errMissingAddress, errTimeout, ErrWriteToConnected, io.ErrUnexpectedEOF:
 		return nil
 	}
 	return fmt.Errorf("unexpected type on 2nd nested level: %T", nestedErr)

src/net/ip.go

@@ -377,6 +377,10 @@ func bytesEqual(x, y []byte) bool {
 	return true
 }
 
+func (ip IP) matchAddrFamily(x IP) bool {
+	return ip.To4() != nil && x.To4() != nil || ip.To16() != nil && ip.To4() == nil && x.To16() != nil && x.To4() == nil
+}
+
 // If mask is a sequence of 1 bits followed by 0 bits,
 // return the number of 1 bits.
 func simpleMaskLength(mask IPMask) int {

src/net/ipsock.go

@@ -6,10 +6,7 @@
 
 package net
 
-import (
-	"errors"
-	"time"
-)
+import "time"
 
 var (
 	// supportsIPv4 reports whether the platform supports IPv4
@@ -73,8 +70,6 @@ func (addrs addrList) partition(strategy func(Addr) bool) (primaries, fallbacks
 	return
 }
 
-var errNoSuitableAddress = errors.New("no suitable address found")
-
 // filterAddrList applies a filter to a list of IP addresses,
 // yielding a list of Addr objects. Known filters are nil, ipv4only,
 // and ipv6only. It returns every address when the filter is nil.

src/net/net.go

@@ -364,6 +364,9 @@ type Error interface {
 
 // Various errors contained in OpError.
 var (
+	// For connection setup operations.
+	errNoSuitableAddress = errors.New("no suitable address found")
+
 	// For connection setup and write operations.
 	errMissingAddress = errors.New("missing address")