net: remove the alloc from ReadMsgUDPAddrPort

name                          old time/op    new time/op    delta
ReadWriteMsgUDPAddrPort-8       4.95µs ± 5%    4.55µs ± 1%    -7.96%  (p=0.016 n=5+4)

name                          old alloc/op   new alloc/op   delta
ReadWriteMsgUDPAddrPort-8        32.0B ± 0%      0.0B       -100.00%  (p=0.008 n=5+5)

name                          old allocs/op  new allocs/op  delta
ReadWriteMsgUDPAddrPort-8         1.00 ± 0%      0.00       -100.00%  (p=0.008 n=5+5)

Change-Id: Ib968c6f2968926ec9a364dd52063cd0d7c29b10c
Reviewed-on: https://go-review.googlesource.com/c/go/+/360862
Trust: Josh Bleecher Snyder <josharian@gmail.com>
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/internal/poll/fd_unix.go

@@ -311,6 +311,60 @@ func (fd *FD) ReadMsg(p []byte, oob []byte, flags int) (int, int, int, syscall.S
 	}
 }
 
+// ReadMsgInet4 is ReadMsg, but specialized for syscall.SockaddrInet4.
+func (fd *FD) ReadMsgInet4(p []byte, oob []byte, flags int, sa4 *syscall.SockaddrInet4) (int, int, int, error) {
+	if err := fd.readLock(); err != nil {
+		return 0, 0, 0, err
+	}
+	defer fd.readUnlock()
+	if err := fd.pd.prepareRead(fd.isFile); err != nil {
+		return 0, 0, 0, err
+	}
+	for {
+		n, oobn, sysflags, err := unix.RecvmsgInet4(fd.Sysfd, p, oob, flags, sa4)
+		if err != nil {
+			if err == syscall.EINTR {
+				continue
+			}
+			// TODO(dfc) should n and oobn be set to 0
+			if err == syscall.EAGAIN && fd.pd.pollable() {
+				if err = fd.pd.waitRead(fd.isFile); err == nil {
+					continue
+				}
+			}
+		}
+		err = fd.eofError(n, err)
+		return n, oobn, sysflags, err
+	}
+}
+
+// ReadMsgInet6 is ReadMsg, but specialized for syscall.SockaddrInet6.
+func (fd *FD) ReadMsgInet6(p []byte, oob []byte, flags int, sa6 *syscall.SockaddrInet6) (int, int, int, error) {
+	if err := fd.readLock(); err != nil {
+		return 0, 0, 0, err
+	}
+	defer fd.readUnlock()
+	if err := fd.pd.prepareRead(fd.isFile); err != nil {
+		return 0, 0, 0, err
+	}
+	for {
+		n, oobn, sysflags, err := unix.RecvmsgInet6(fd.Sysfd, p, oob, flags, sa6)
+		if err != nil {
+			if err == syscall.EINTR {
+				continue
+			}
+			// TODO(dfc) should n and oobn be set to 0
+			if err == syscall.EAGAIN && fd.pd.pollable() {
+				if err = fd.pd.waitRead(fd.isFile); err == nil {
+					continue
+				}
+			}
+		}
+		err = fd.eofError(n, err)
+		return n, oobn, sysflags, err
+	}
+}
+
 // Write implements io.Writer.
 func (fd *FD) Write(p []byte) (int, error) {
 	if err := fd.writeLock(); err != nil {

src/internal/poll/fd_windows.go

@@ -620,10 +620,7 @@ func (fd *FD) ReadFromInet4(buf []byte, sa4 *syscall.SockaddrInet4) (int, error)
 	if err != nil {
 		return n, err
 	}
-	sa, _ := o.rsa.Sockaddr()
-	if sa != nil {
-		*sa4 = *(sa.(*syscall.SockaddrInet4))
-	}
+	rawToSockaddrInet4(o.rsa, sa4)
 	return n, err
 }
 
@@ -652,10 +649,7 @@ func (fd *FD) ReadFromInet6(buf []byte, sa6 *syscall.SockaddrInet6) (int, error)
 	if err != nil {
 		return n, err
 	}
-	sa, _ := o.rsa.Sockaddr()
-	if sa != nil {
-		*sa6 = *(sa.(*syscall.SockaddrInet6))
-	}
+	rawToSockaddrInet6(o.rsa, sa6)
 	return n, err
 }
 
@@ -1149,6 +1143,21 @@ func sockaddrInet6ToRaw(sa syscall.SockaddrInet6) (unsafe.Pointer, int32) {
 	return unsafe.Pointer(&raw), int32(unsafe.Sizeof(raw))
 }
 
+func rawToSockaddrInet4(rsa *syscall.RawSockaddrAny, sa *syscall.SockaddrInet4) {
+	pp := (*syscall.RawSockaddrInet4)(unsafe.Pointer(rsa))
+	p := (*[2]byte)(unsafe.Pointer(&pp.Port))
+	sa.Port = int(p[0])<<8 + int(p[1])
+	sa.Addr = pp.Addr
+}
+
+func rawToSockaddrInet6(rsa *syscall.RawSockaddrAny, sa *syscall.SockaddrInet6) {
+	pp := (*syscall.RawSockaddrInet6)(unsafe.Pointer(rsa))
+	p := (*[2]byte)(unsafe.Pointer(&pp.Port))
+	sa.Port = int(p[0])<<8 + int(p[1])
+	sa.ZoneId = pp.Scope_id
+	sa.Addr = pp.Addr
+}
+
 func sockaddrToRaw(sa syscall.Sockaddr) (unsafe.Pointer, int32, error) {
 	switch sa := sa.(type) {
 	case *syscall.SockaddrInet4:
@@ -1190,6 +1199,60 @@ func (fd *FD) ReadMsg(p []byte, oob []byte, flags int) (int, int, int, syscall.S
 	return n, int(o.msg.Control.Len), int(o.msg.Flags), sa, err
 }
 
+// ReadMsgInet4 is ReadMsg, but specialized to return a syscall.SockaddrInet4.
+func (fd *FD) ReadMsgInet4(p []byte, oob []byte, flags int, sa4 *syscall.SockaddrInet4) (int, int, int, error) {
+	if err := fd.readLock(); err != nil {
+		return 0, 0, 0, err
+	}
+	defer fd.readUnlock()
+
+	if len(p) > maxRW {
+		p = p[:maxRW]
+	}
+
+	o := &fd.rop
+	o.InitMsg(p, oob)
+	o.rsa = new(syscall.RawSockaddrAny)
+	o.msg.Name = (syscall.Pointer)(unsafe.Pointer(o.rsa))
+	o.msg.Namelen = int32(unsafe.Sizeof(*o.rsa))
+	o.msg.Flags = uint32(flags)
+	n, err := execIO(o, func(o *operation) error {
+		return windows.WSARecvMsg(o.fd.Sysfd, &o.msg, &o.qty, &o.o, nil)
+	})
+	err = fd.eofError(n, err)
+	if err == nil {
+		rawToSockaddrInet4(o.rsa, sa4)
+	}
+	return n, int(o.msg.Control.Len), int(o.msg.Flags), err
+}
+
+// ReadMsgInet6 is ReadMsg, but specialized to return a syscall.SockaddrInet6.
+func (fd *FD) ReadMsgInet6(p []byte, oob []byte, flags int, sa6 *syscall.SockaddrInet6) (int, int, int, error) {
+	if err := fd.readLock(); err != nil {
+		return 0, 0, 0, err
+	}
+	defer fd.readUnlock()
+
+	if len(p) > maxRW {
+		p = p[:maxRW]
+	}
+
+	o := &fd.rop
+	o.InitMsg(p, oob)
+	o.rsa = new(syscall.RawSockaddrAny)
+	o.msg.Name = (syscall.Pointer)(unsafe.Pointer(o.rsa))
+	o.msg.Namelen = int32(unsafe.Sizeof(*o.rsa))
+	o.msg.Flags = uint32(flags)
+	n, err := execIO(o, func(o *operation) error {
+		return windows.WSARecvMsg(o.fd.Sysfd, &o.msg, &o.qty, &o.o, nil)
+	})
+	err = fd.eofError(n, err)
+	if err == nil {
+		rawToSockaddrInet6(o.rsa, sa6)
+	}
+	return n, int(o.msg.Control.Len), int(o.msg.Flags), err
+}
+
 // WriteMsg wraps the WSASendMsg network call.
 func (fd *FD) WriteMsg(p []byte, oob []byte, sa syscall.Sockaddr) (int, int, error) {
 	if len(p) > maxRW {

src/internal/syscall/unix/net.go

@@ -34,3 +34,11 @@ func SendmsgNInet4(fd int, p, oob []byte, to syscall.SockaddrInet4, flags int) (
 //go:linkname SendmsgNInet6 syscall.sendmsgNInet6
 //go:noescape
 func SendmsgNInet6(fd int, p, oob []byte, to syscall.SockaddrInet6, flags int) (n int, err error)
+
+//go:linkname RecvmsgInet4 syscall.recvmsgInet4
+//go:noescape
+func RecvmsgInet4(fd int, p, oob []byte, flags int, from *syscall.SockaddrInet4) (n, oobn int, recvflags int, err error)
+
+//go:linkname RecvmsgInet6 syscall.recvmsgInet6
+//go:noescape
+func RecvmsgInet6(fd int, p, oob []byte, flags int, from *syscall.SockaddrInet6) (n, oobn int, recvflags int, err error)

src/internal/syscall/unix/net_js.go

@@ -34,3 +34,11 @@ func SendmsgNInet4(fd int, p, oob []byte, to syscall.SockaddrInet4, flags int) (
 func SendmsgNInet6(fd int, p, oob []byte, to syscall.SockaddrInet6, flags int) (n int, err error) {
 	return 0, syscall.ENOSYS
 }
+
+func RecvmsgInet4(fd int, p, oob []byte, flags int, from *syscall.SockaddrInet4) (n, oobn int, recvflags int, err error) {
+	return 0, 0, 0, syscall.ENOSYS
+}
+
+func RecvmsgInet6(fd int, p, oob []byte, flags int, from *syscall.SockaddrInet6) (n, oobn int, recvflags int, err error) {
+	return 0, 0, 0, syscall.ENOSYS
+}

src/net/fd_posix.go

@@ -80,6 +80,18 @@ func (fd *netFD) readMsg(p []byte, oob []byte, flags int) (n, oobn, retflags int
 	return n, oobn, retflags, sa, wrapSyscallError(readMsgSyscallName, err)
 }
 
+func (fd *netFD) readMsgInet4(p []byte, oob []byte, flags int, sa *syscall.SockaddrInet4) (n, oobn, retflags int, err error) {
+	n, oobn, retflags, err = fd.pfd.ReadMsgInet4(p, oob, flags, sa)
+	runtime.KeepAlive(fd)
+	return n, oobn, retflags, wrapSyscallError(readMsgSyscallName, err)
+}
+
+func (fd *netFD) readMsgInet6(p []byte, oob []byte, flags int, sa *syscall.SockaddrInet6) (n, oobn, retflags int, err error) {
+	n, oobn, retflags, err = fd.pfd.ReadMsgInet6(p, oob, flags, sa)
+	runtime.KeepAlive(fd)
+	return n, oobn, retflags, wrapSyscallError(readMsgSyscallName, err)
+}
+
 func (fd *netFD) Write(p []byte) (nn int, err error) {
 	nn, err = fd.pfd.Write(p)
 	runtime.KeepAlive(fd)

src/net/net_fake.go

@@ -279,6 +279,14 @@ func (fd *netFD) readMsg(p []byte, oob []byte, flags int) (n, oobn, retflags int
 	return 0, 0, 0, nil, syscall.ENOSYS
 }
 
+func (fd *netFD) readMsgInet4(p []byte, oob []byte, flags int, sa *syscall.SockaddrInet4) (n, oobn, retflags int, err error) {
+	return 0, 0, 0, syscall.ENOSYS
+}
+
+func (fd *netFD) readMsgInet6(p []byte, oob []byte, flags int, sa *syscall.SockaddrInet6) (n, oobn, retflags int, err error) {
+	return 0, 0, 0, syscall.ENOSYS
+}
+
 func (fd *netFD) writeMsgInet4(p []byte, oob []byte, sa syscall.SockaddrInet4) (n int, oobn int, err error) {
 	return 0, 0, syscall.ENOSYS
 }

src/net/udpsock_posix.go

@@ -95,13 +95,15 @@ func (c *UDPConn) readFromAddrPort(b []byte) (n int, addr netip.AddrPort, err er
 }
 
 func (c *UDPConn) readMsg(b, oob []byte) (n, oobn, flags int, addr netip.AddrPort, err error) {
-	var sa syscall.Sockaddr
-	n, oobn, flags, sa, err = c.fd.readMsg(b, oob, 0)
-	switch sa := sa.(type) {
-	case *syscall.SockaddrInet4:
+	switch c.fd.family {
+	case syscall.AF_INET:
+		var sa syscall.SockaddrInet4
+		n, oobn, flags, err = c.fd.readMsgInet4(b, oob, 0, &sa)
 		ip := netip.AddrFrom4(sa.Addr)
 		addr = netip.AddrPortFrom(ip, uint16(sa.Port))
-	case *syscall.SockaddrInet6:
+	case syscall.AF_INET6:
+		var sa syscall.SockaddrInet6
+		n, oobn, flags, err = c.fd.readMsgInet6(b, oob, 0, &sa)
 		ip := netip.AddrFrom16(sa.Addr).WithZone(zoneCache.name(int(sa.ZoneId)))
 		addr = netip.AddrPortFrom(ip, uint16(sa.Port))
 	}

src/syscall/syscall_unix.go

@@ -324,6 +324,33 @@ func recvfromInet6(fd int, p []byte, flags int, from *SockaddrInet6) (n int, err
 	return
 }
 
+func recvmsgInet4(fd int, p, oob []byte, flags int, from *SockaddrInet4) (n, oobn int, recvflags int, err error) {
+	var rsa RawSockaddrAny
+	n, oobn, recvflags, err = recvmsgRaw(fd, p, oob, flags, &rsa)
+	if err != nil {
+		return
+	}
+	pp := (*RawSockaddrInet4)(unsafe.Pointer(&rsa))
+	port := (*[2]byte)(unsafe.Pointer(&pp.Port))
+	from.Port = int(port[0])<<8 + int(port[1])
+	from.Addr = pp.Addr
+	return
+}
+
+func recvmsgInet6(fd int, p, oob []byte, flags int, from *SockaddrInet6) (n, oobn int, recvflags int, err error) {
+	var rsa RawSockaddrAny
+	n, oobn, recvflags, err = recvmsgRaw(fd, p, oob, flags, &rsa)
+	if err != nil {
+		return
+	}
+	pp := (*RawSockaddrInet6)(unsafe.Pointer(&rsa))
+	port := (*[2]byte)(unsafe.Pointer(&pp.Port))
+	from.Port = int(port[0])<<8 + int(port[1])
+	from.ZoneId = pp.Scope_id
+	from.Addr = pp.Addr
+	return
+}
+
 func Recvmsg(fd int, p, oob []byte, flags int) (n, oobn int, recvflags int, from Sockaddr, err error) {
 	var rsa RawSockaddrAny
 	n, oobn, recvflags, err = recvmsgRaw(fd, p, oob, flags, &rsa)