diff --git a/unum/vendor/golang.org/x/net/ipv4/sys_windows.go b/unum/vendor/golang.org/x/net/ipv4/sys_windows.go
new file mode 100644
index 0000000..b0913d5
--- /dev/null
+++ b/unum/vendor/golang.org/x/net/ipv4/sys_windows.go
@@ -0,0 +1,67 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ipv4
+
+import (
+	"golang.org/x/net/internal/iana"
+	"golang.org/x/net/internal/socket"
+)
+
+const (
+	// See ws2tcpip.h.
+	sysIP_OPTIONS                = 0x1
+	sysIP_HDRINCL                = 0x2
+	sysIP_TOS                    = 0x3
+	sysIP_TTL                    = 0x4
+	sysIP_MULTICAST_IF           = 0x9
+	sysIP_MULTICAST_TTL          = 0xa
+	sysIP_MULTICAST_LOOP         = 0xb
+	sysIP_ADD_MEMBERSHIP         = 0xc
+	sysIP_DROP_MEMBERSHIP        = 0xd
+	sysIP_DONTFRAGMENT           = 0xe
+	sysIP_ADD_SOURCE_MEMBERSHIP  = 0xf
+	sysIP_DROP_SOURCE_MEMBERSHIP = 0x10
+	sysIP_PKTINFO                = 0x13
+
+	sizeofInetPktinfo  = 0x8
+	sizeofIPMreq       = 0x8
+	sizeofIPMreqSource = 0xc
+)
+
+type inetPktinfo struct {
+	Addr    [4]byte
+	Ifindex int32
+}
+
+type ipMreq struct {
+	Multiaddr [4]byte
+	Interface [4]byte
+}
+
+type ipMreqSource struct {
+	Multiaddr  [4]byte
+	Sourceaddr [4]byte
+	Interface  [4]byte
+}
+
+// See http://msdn.microsoft.com/en-us/library/windows/desktop/ms738586(v=vs.85).aspx
+var (
+	ctlOpts = [ctlMax]ctlOpt{}
+
+	sockOpts = map[int]*sockOpt{
+		ssoTOS:                {Option: socket.Option{Level: iana.ProtocolIP, Name: sysIP_TOS, Len: 4}},
+		ssoTTL:                {Option: socket.Option{Level: iana.ProtocolIP, Name: sysIP_TTL, Len: 4}},
+		ssoMulticastTTL:       {Option: socket.Option{Level: iana.ProtocolIP, Name: sysIP_MULTICAST_TTL, Len: 4}},
+		ssoMulticastInterface: {Option: socket.Option{Level: iana.ProtocolIP, Name: sysIP_MULTICAST_IF, Len: 4}},
+		ssoMulticastLoopback:  {Option: socket.Option{Level: iana.ProtocolIP, Name: sysIP_MULTICAST_LOOP, Len: 4}},
+		ssoHeaderPrepend:      {Option: socket.Option{Level: iana.ProtocolIP, Name: sysIP_HDRINCL, Len: 4}},
+		ssoJoinGroup:          {Option: socket.Option{Level: iana.ProtocolIP, Name: sysIP_ADD_MEMBERSHIP, Len: sizeofIPMreq}, typ: ssoTypeIPMreq},
+		ssoLeaveGroup:         {Option: socket.Option{Level: iana.ProtocolIP, Name: sysIP_DROP_MEMBERSHIP, Len: sizeofIPMreq}, typ: ssoTypeIPMreq},
+	}
+)
+
+func (pi *inetPktinfo) setIfindex(i int) {
+	pi.Ifindex = int32(i)
+}