[release-branch.go1.24] net: fix WriteMsgUDPAddrPort addr handling on IPv4 sockets
Accept IPv4-mapped IPv6 destination addresses on IPv4 UDP sockets.
Fixes #74818.
Change-Id: I4624b9b8f861aedcae29e51d5298d23ce1c0f2c7
Reviewed-on: https://go-review.googlesource.com/c/go/+/689976
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Mark Freeman <markfreeman@google.com>
Reviewed-by: Damien Neil <dneil@google.com>
(cherry picked from commit bdb2d50fdf40706e7d7411f33ade80edac726707)
Reviewed-on: https://go-review.googlesource.com/c/go/+/695656
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Carlos Amedee <carlos@golang.org>
diff --git a/src/net/ipsock_posix.go b/src/net/ipsock_posix.go
index 2aeabd4..52712f9 100644
--- a/src/net/ipsock_posix.go
+++ b/src/net/ipsock_posix.go
@@ -237,8 +237,12 @@
func addrPortToSockaddrInet4(ap netip.AddrPort) (syscall.SockaddrInet4, error) {
// ipToSockaddrInet4 has special handling here for zero length slices.
// We do not, because netip has no concept of a generic zero IP address.
+ //
+ // addr is allowed to be an IPv4-mapped IPv6 address.
+ // As4 will unmap it to an IPv4 address.
+ // The error message is kept consistent with ipToSockaddrInet4.
addr := ap.Addr()
- if !addr.Is4() {
+ if !addr.Is4() && !addr.Is4In6() {
return syscall.SockaddrInet4{}, &AddrError{Err: "non-IPv4 address", Addr: addr.String()}
}
sa := syscall.SockaddrInet4{
diff --git a/src/net/udpsock_test.go b/src/net/udpsock_test.go
index 6dacc81..7ad8a58 100644
--- a/src/net/udpsock_test.go
+++ b/src/net/udpsock_test.go
@@ -705,3 +705,35 @@
t.Fatal(err)
}
}
+
+// TestIPv4WriteMsgUDPAddrPortTargetAddrIPVersion verifies that
+// WriteMsgUDPAddrPort accepts IPv4 and IPv4-mapped IPv6 destination addresses,
+// and rejects IPv6 destination addresses on a "udp4" connection.
+func TestIPv4WriteMsgUDPAddrPortTargetAddrIPVersion(t *testing.T) {
+ if !testableNetwork("udp4") {
+ t.Skipf("skipping: udp4 not available")
+ }
+
+ conn, err := ListenUDP("udp4", &UDPAddr{IP: IPv4(127, 0, 0, 1)})
+ if err != nil {
+ t.Fatal(err)
+ }
+ defer conn.Close()
+
+ daddr4 := netip.AddrPortFrom(netip.MustParseAddr("127.0.0.1"), 12345)
+ daddr4in6 := netip.AddrPortFrom(netip.MustParseAddr("::ffff:127.0.0.1"), 12345)
+ daddr6 := netip.AddrPortFrom(netip.MustParseAddr("::1"), 12345)
+ buf := make([]byte, 8)
+
+ if _, _, err = conn.WriteMsgUDPAddrPort(buf, nil, daddr4); err != nil {
+ t.Errorf("conn.WriteMsgUDPAddrPort(buf, nil, daddr4) failed: %v", err)
+ }
+
+ if _, _, err = conn.WriteMsgUDPAddrPort(buf, nil, daddr4in6); err != nil {
+ t.Errorf("conn.WriteMsgUDPAddrPort(buf, nil, daddr4in6) failed: %v", err)
+ }
+
+ if _, _, err = conn.WriteMsgUDPAddrPort(buf, nil, daddr6); err == nil {
+ t.Errorf("conn.WriteMsgUDPAddrPort(buf, nil, daddr6) should have failed, but got no error")
+ }
+}
