tunnel: wait for IP service to attach to wintun

This helps fix startup races without needing to poll, as well as
reconfiguring interfaces after wintun destroys and re-adds. It also
deals gracefully with IPv6 being disabled.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

2 files changed, 69 insertions, 2 deletions

diff --git a/tunnel/winipcfg/luid.go b/tunnel/winipcfg/luid.go
index ff7061d2..396fbbb2 100644
--- a/tunnel/winipcfg/luid.go
+++ b/tunnel/winipcfg/luid.go
@@ -116,6 +116,27 @@ func (luid LUID) SetIPAddresses(addresses []net.IPNet) error {
 	return luid.AddIPAddresses(addresses)
 }
 
+// SetIPAddressesForFamily method sets new unicast IP addresses for a specific family to the interface.
+func (luid LUID) SetIPAddressesForFamily(family AddressFamily, addresses []net.IPNet) error {
+	err := luid.FlushIPAddresses(family)
+	if err != nil {
+		return err
+	}
+	for i := range addresses {
+		asV4 := addresses[i].IP.To4()
+		if asV4 == nil && family == windows.AF_INET {
+			continue
+		} else if asV4 != nil && family == windows.AF_INET6 {
+			continue
+		}
+		err := luid.AddIPAddress(addresses[i])
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
 // DeleteIPAddress method deletes interface's unicast IP address. Corresponds to DeleteUnicastIpAddressEntry function
 // (https://docs.microsoft.com/en-us/windows/desktop/api/netioapi/nf-netioapi-deleteunicastipaddressentry).
 func (luid LUID) DeleteIPAddress(address net.IPNet) error {
@@ -210,6 +231,27 @@ func (luid LUID) SetRoutes(routesData []*RouteData) error {
 	return luid.AddRoutes(routesData)
 }
 
+// SetRoutesForFamily method sets (flush than add) multiple routes for a specific family to the interface.
+func (luid LUID) SetRoutesForFamily(family AddressFamily, routesData []*RouteData) error {
+	err := luid.FlushRoutes(family)
+	if err != nil {
+		return err
+	}
+	for _, rd := range routesData {
+		asV4 := rd.Destination.IP.To4()
+		if asV4 == nil && family == windows.AF_INET {
+			continue
+		} else if asV4 != nil && family == windows.AF_INET6 {
+			continue
+		}
+		err := luid.AddRoute(rd.Destination, rd.NextHop, rd.Metric)
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
 // DeleteRoute method deletes a route that matches the criteria. Corresponds to DeleteIpForwardEntry2 function
 // (https://docs.microsoft.com/en-us/windows/desktop/api/netioapi/nf-netioapi-deleteipforwardentry2).
 func (luid LUID) DeleteRoute(destination net.IPNet, nextHop net.IP) error {
@@ -359,3 +401,28 @@ func (luid LUID) SetDNS(dnses []net.IP) error {
 	}
 	return runNetsh(cmds)
 }
+
+// SetDNSForFamily method clears previous and associates new DNS servers with the adapter for a specific family.
+func (luid LUID) SetDNSForFamily(family AddressFamily, dnses []net.IP) error {
+	var templateFlush string
+	if family == windows.AF_INET {
+		templateFlush = netshCmdTemplateFlush4
+	} else if family == windows.AF_INET6 {
+		templateFlush = netshCmdTemplateFlush6
+	}
+
+	cmds := make([]string, 0, 1+len(dnses))
+	ipif, err := luid.IPInterface(family)
+	if err != nil {
+		return err
+	}
+	cmds = append(cmds, fmt.Sprintf(templateFlush, ipif.InterfaceIndex))
+	for i := 0; i < len(dnses); i++ {
+		if v4 := dnses[i].To4(); v4 != nil && family == windows.AF_INET {
+			cmds = append(cmds, fmt.Sprintf(netshCmdTemplateAdd4, ipif.InterfaceIndex, v4.String()))
+		} else if v6 := dnses[i].To16(); v4 == nil && v6 != nil && family == windows.AF_INET6 {
+			cmds = append(cmds, fmt.Sprintf(netshCmdTemplateAdd6, ipif.InterfaceIndex, v6.String()))
+		}
+	}
+	return runNetsh(cmds)
+}
diff --git a/tunnel/winipcfg/winipcfg.go b/tunnel/winipcfg/winipcfg.go
index 5af9f1aa..2fc0c875 100644
--- a/tunnel/winipcfg/winipcfg.go
+++ b/tunnel/winipcfg/winipcfg.go
@@ -32,13 +32,13 @@ import (
 
 // GetAdaptersAddresses function retrieves the addresses associated with the adapters on the local computer.
 // https://docs.microsoft.com/en-us/windows/desktop/api/iphlpapi/nf-iphlpapi-getadaptersaddresses
-func GetAdaptersAddresses(family uint32, flags GAAFlags) ([]*IPAdapterAddresses, error) {
+func GetAdaptersAddresses(family AddressFamily, flags GAAFlags) ([]*IPAdapterAddresses, error) {
 	var b []byte
 	size := uint32(15000)
 
 	for {
 		b = make([]byte, size)
-		err := windows.GetAdaptersAddresses(family, uint32(flags), 0, (*windows.IpAdapterAddresses)(unsafe.Pointer(&b[0])), &size)
+		err := windows.GetAdaptersAddresses(uint32(family), uint32(flags), 0, (*windows.IpAdapterAddresses)(unsafe.Pointer(&b[0])), &size)
 		if err == nil {
 			break
 		}