diff --git a/unum/vendor/golang.org/x/net/ipv6/sys_darwin.go b/unum/vendor/golang.org/x/net/ipv6/sys_darwin.go
new file mode 100644
index 0000000..e3d0443
--- /dev/null
+++ b/unum/vendor/golang.org/x/net/ipv6/sys_darwin.go
@@ -0,0 +1,106 @@
+// Copyright 2013 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 ipv6
+
+import (
+	"net"
+	"strconv"
+	"strings"
+	"syscall"
+	"unsafe"
+
+	"golang.org/x/net/internal/iana"
+	"golang.org/x/net/internal/socket"
+)
+
+var (
+	ctlOpts = [ctlMax]ctlOpt{
+		ctlHopLimit:   {sysIPV6_2292HOPLIMIT, 4, marshal2292HopLimit, parseHopLimit},
+		ctlPacketInfo: {sysIPV6_2292PKTINFO, sizeofInet6Pktinfo, marshal2292PacketInfo, parsePacketInfo},
+	}
+
+	sockOpts = map[int]*sockOpt{
+		ssoHopLimit:           {Option: socket.Option{Level: iana.ProtocolIPv6, Name: sysIPV6_UNICAST_HOPS, Len: 4}},
+		ssoMulticastInterface: {Option: socket.Option{Level: iana.ProtocolIPv6, Name: sysIPV6_MULTICAST_IF, Len: 4}},
+		ssoMulticastHopLimit:  {Option: socket.Option{Level: iana.ProtocolIPv6, Name: sysIPV6_MULTICAST_HOPS, Len: 4}},
+		ssoMulticastLoopback:  {Option: socket.Option{Level: iana.ProtocolIPv6, Name: sysIPV6_MULTICAST_LOOP, Len: 4}},
+		ssoReceiveHopLimit:    {Option: socket.Option{Level: iana.ProtocolIPv6, Name: sysIPV6_2292HOPLIMIT, Len: 4}},
+		ssoReceivePacketInfo:  {Option: socket.Option{Level: iana.ProtocolIPv6, Name: sysIPV6_2292PKTINFO, Len: 4}},
+		ssoChecksum:           {Option: socket.Option{Level: iana.ProtocolIPv6, Name: sysIPV6_CHECKSUM, Len: 4}},
+		ssoICMPFilter:         {Option: socket.Option{Level: iana.ProtocolIPv6ICMP, Name: sysICMP6_FILTER, Len: sizeofICMPv6Filter}},
+		ssoJoinGroup:          {Option: socket.Option{Level: iana.ProtocolIPv6, Name: sysIPV6_JOIN_GROUP, Len: sizeofIPv6Mreq}, typ: ssoTypeIPMreq},
+		ssoLeaveGroup:         {Option: socket.Option{Level: iana.ProtocolIPv6, Name: sysIPV6_LEAVE_GROUP, Len: sizeofIPv6Mreq}, typ: ssoTypeIPMreq},
+	}
+)
+
+func init() {
+	// Seems like kern.osreldate is veiled on latest OS X. We use
+	// kern.osrelease instead.
+	s, err := syscall.Sysctl("kern.osrelease")
+	if err != nil {
+		return
+	}
+	ss := strings.Split(s, ".")
+	if len(ss) == 0 {
+		return
+	}
+	// The IP_PKTINFO and protocol-independent multicast API were
+	// introduced in OS X 10.7 (Darwin 11). But it looks like
+	// those features require OS X 10.8 (Darwin 12) or above.
+	// See http://support.apple.com/kb/HT1633.
+	if mjver, err := strconv.Atoi(ss[0]); err != nil || mjver < 12 {
+		return
+	}
+	ctlOpts[ctlTrafficClass] = ctlOpt{sysIPV6_TCLASS, 4, marshalTrafficClass, parseTrafficClass}
+	ctlOpts[ctlHopLimit] = ctlOpt{sysIPV6_HOPLIMIT, 4, marshalHopLimit, parseHopLimit}
+	ctlOpts[ctlPacketInfo] = ctlOpt{sysIPV6_PKTINFO, sizeofInet6Pktinfo, marshalPacketInfo, parsePacketInfo}
+	ctlOpts[ctlNextHop] = ctlOpt{sysIPV6_NEXTHOP, sizeofSockaddrInet6, marshalNextHop, parseNextHop}
+	ctlOpts[ctlPathMTU] = ctlOpt{sysIPV6_PATHMTU, sizeofIPv6Mtuinfo, marshalPathMTU, parsePathMTU}
+	sockOpts[ssoTrafficClass] = &sockOpt{Option: socket.Option{Level: iana.ProtocolIPv6, Name: sysIPV6_TCLASS, Len: 4}}
+	sockOpts[ssoReceiveTrafficClass] = &sockOpt{Option: socket.Option{Level: iana.ProtocolIPv6, Name: sysIPV6_RECVTCLASS, Len: 4}}
+	sockOpts[ssoReceiveHopLimit] = &sockOpt{Option: socket.Option{Level: iana.ProtocolIPv6, Name: sysIPV6_RECVHOPLIMIT, Len: 4}}
+	sockOpts[ssoReceivePacketInfo] = &sockOpt{Option: socket.Option{Level: iana.ProtocolIPv6, Name: sysIPV6_RECVPKTINFO, Len: 4}}
+	sockOpts[ssoReceivePathMTU] = &sockOpt{Option: socket.Option{Level: iana.ProtocolIPv6, Name: sysIPV6_RECVPATHMTU, Len: 4}}
+	sockOpts[ssoPathMTU] = &sockOpt{Option: socket.Option{Level: iana.ProtocolIPv6, Name: sysIPV6_PATHMTU, Len: sizeofIPv6Mtuinfo}}
+	sockOpts[ssoJoinGroup] = &sockOpt{Option: socket.Option{Level: iana.ProtocolIPv6, Name: sysMCAST_JOIN_GROUP, Len: sizeofGroupReq}, typ: ssoTypeGroupReq}
+	sockOpts[ssoLeaveGroup] = &sockOpt{Option: socket.Option{Level: iana.ProtocolIPv6, Name: sysMCAST_LEAVE_GROUP, Len: sizeofGroupReq}, typ: ssoTypeGroupReq}
+	sockOpts[ssoJoinSourceGroup] = &sockOpt{Option: socket.Option{Level: iana.ProtocolIPv6, Name: sysMCAST_JOIN_SOURCE_GROUP, Len: sizeofGroupSourceReq}, typ: ssoTypeGroupSourceReq}
+	sockOpts[ssoLeaveSourceGroup] = &sockOpt{Option: socket.Option{Level: iana.ProtocolIPv6, Name: sysMCAST_LEAVE_SOURCE_GROUP, Len: sizeofGroupSourceReq}, typ: ssoTypeGroupSourceReq}
+	sockOpts[ssoBlockSourceGroup] = &sockOpt{Option: socket.Option{Level: iana.ProtocolIPv6, Name: sysMCAST_BLOCK_SOURCE, Len: sizeofGroupSourceReq}, typ: ssoTypeGroupSourceReq}
+	sockOpts[ssoUnblockSourceGroup] = &sockOpt{Option: socket.Option{Level: iana.ProtocolIPv6, Name: sysMCAST_UNBLOCK_SOURCE, Len: sizeofGroupSourceReq}, typ: ssoTypeGroupSourceReq}
+}
+
+func (sa *sockaddrInet6) setSockaddr(ip net.IP, i int) {
+	sa.Len = sizeofSockaddrInet6
+	sa.Family = syscall.AF_INET6
+	copy(sa.Addr[:], ip)
+	sa.Scope_id = uint32(i)
+}
+
+func (pi *inet6Pktinfo) setIfindex(i int) {
+	pi.Ifindex = uint32(i)
+}
+
+func (mreq *ipv6Mreq) setIfindex(i int) {
+	mreq.Interface = uint32(i)
+}
+
+func (gr *groupReq) setGroup(grp net.IP) {
+	sa := (*sockaddrInet6)(unsafe.Pointer(uintptr(unsafe.Pointer(gr)) + 4))
+	sa.Len = sizeofSockaddrInet6
+	sa.Family = syscall.AF_INET6
+	copy(sa.Addr[:], grp)
+}
+
+func (gsr *groupSourceReq) setSourceGroup(grp, src net.IP) {
+	sa := (*sockaddrInet6)(unsafe.Pointer(uintptr(unsafe.Pointer(gsr)) + 4))
+	sa.Len = sizeofSockaddrInet6
+	sa.Family = syscall.AF_INET6
+	copy(sa.Addr[:], grp)
+	sa = (*sockaddrInet6)(unsafe.Pointer(uintptr(unsafe.Pointer(gsr)) + 132))
+	sa.Len = sizeofSockaddrInet6
+	sa.Family = syscall.AF_INET6
+	copy(sa.Addr[:], src)
+}