internal/poll: remove alloc sending IPv6 UDP on Windows

This was an oversight in CL 331511.

Change-Id: Ibc20bf6ea80a8675d43d9691ed551dffab1d9215
Reviewed-on: https://go-review.googlesource.com/c/go/+/361254
Trust: Josh Bleecher Snyder <josharian@gmail.com>
Trust: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>

diff --git a/src/internal/poll/fd_windows.go b/src/internal/poll/fd_windows.go
index 0f5ae8e0d4091433c4dd1bc48cb397872ace1a03..139f78a7c15e78bd059f15c7c702780c7f95eb48 100644 (file)
--- a/src/internal/poll/fd_windows.go
+++ b/src/internal/poll/fd_windows.go
@@ -857,7 +857,7 @@ func (fd *FD) WriteTo(buf []byte, sa syscall.Sockaddr) (int, error) {
        return ntotal, nil
 }
 
-// WriteTo wraps the sendto network call for IPv4.
+// WriteToInet4 is WriteTo, specialized for syscall.SockaddrInet4.
 func (fd *FD) WriteToInet4(buf []byte, sa4 syscall.SockaddrInet4) (int, error) {
        if err := fd.writeLock(); err != nil {
                return 0, err
@@ -896,9 +896,43 @@ func (fd *FD) WriteToInet4(buf []byte, sa4 syscall.SockaddrInet4) (int, error) {
        return ntotal, nil
 }
 
-// WriteTo wraps the sendto network call for IPv6.
-func (fd *FD) WriteToInet6(buf []byte, sa syscall.SockaddrInet6) (int, error) {
-       return fd.WriteTo(buf, &sa)
+// WriteToInet6 is WriteTo, specialized for syscall.SockaddrInet6.
+func (fd *FD) WriteToInet6(buf []byte, sa6 syscall.SockaddrInet6) (int, error) {
+       if err := fd.writeLock(); err != nil {
+               return 0, err
+       }
+       defer fd.writeUnlock()
+
+       if len(buf) == 0 {
+               // handle zero-byte payload
+               o := &fd.wop
+               o.InitBuf(buf)
+               o.sa6 = sa6
+               n, err := execIO(o, func(o *operation) error {
+                       return windows.WSASendtoInet6(o.fd.Sysfd, &o.buf, 1, &o.qty, 0, o.sa6, &o.o, nil)
+               })
+               return n, err
+       }
+
+       ntotal := 0
+       for len(buf) > 0 {
+               b := buf
+               if len(b) > maxRW {
+                       b = b[:maxRW]
+               }
+               o := &fd.wop
+               o.InitBuf(b)
+               o.sa6 = sa6
+               n, err := execIO(o, func(o *operation) error {
+                       return windows.WSASendtoInet6(o.fd.Sysfd, &o.buf, 1, &o.qty, 0, o.sa6, &o.o, nil)
+               })
+               ntotal += int(n)
+               if err != nil {
+                       return ntotal, err
+               }
+               buf = buf[n:]
+       }
+       return ntotal, nil
 }
 
 // Call ConnectEx. This doesn't need any locking, since it is only