internal/poll: permit nil destination address in WriteMsg{Inet4,Inet6}

For #74841

Change-Id: If2ea23b1eb23e32680bd576f54a0020d7e115797
Reviewed-on: https://go-review.googlesource.com/c/go/+/692436
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Carlos Amedee <carlos@golang.org>
Reviewed-by: Damien Neil <dneil@google.com>

diff --git a/src/internal/poll/fd_windows.go b/src/internal/poll/fd_windows.go
index ebb2abcbf81a88779c2b264310f0e00b2d058ee5..5d6d78d8bb4378103e0af1afa9b989688276268d 100644 (file)
--- a/src/internal/poll/fd_windows.go
+++ b/src/internal/poll/fd_windows.go
@@ -1422,10 +1422,13 @@ func (fd *FD) WriteMsgInet4(p []byte, oob []byte, sa *syscall.SockaddrInet4) (in
        if o.rsa == nil {
                o.rsa = new(syscall.RawSockaddrAny)
        }
-       len := sockaddrInet4ToRaw(o.rsa, sa)
+       var nameLen int32
+       if sa != nil {
+               nameLen = sockaddrInet4ToRaw(o.rsa, sa)
+       }
        msg := newWSAMsg(p, oob, 0)
        msg.Name = (syscall.Pointer)(unsafe.Pointer(o.rsa))
-       msg.Namelen = len
+       msg.Namelen = nameLen
        n, err := fd.execIO(o, func(o *operation) (qty uint32, err error) {
                err = windows.WSASendMsg(fd.Sysfd, &msg, 0, nil, &o.o, nil)
                return qty, err
@@ -1449,9 +1452,12 @@ func (fd *FD) WriteMsgInet6(p []byte, oob []byte, sa *syscall.SockaddrInet6) (in
                o.rsa = new(syscall.RawSockaddrAny)
        }
        msg := newWSAMsg(p, oob, 0)
-       len := sockaddrInet6ToRaw(o.rsa, sa)
+       var nameLen int32
+       if sa != nil {
+               nameLen = sockaddrInet6ToRaw(o.rsa, sa)
+       }
        msg.Name = (syscall.Pointer)(unsafe.Pointer(o.rsa))
-       msg.Namelen = len
+       msg.Namelen = nameLen
        n, err := fd.execIO(o, func(o *operation) (qty uint32, err error) {
                err = windows.WSASendMsg(fd.Sysfd, &msg, 0, nil, &o.o, nil)
                return qty, err