wgengine/router: move Tailscale's winipcfg additions into wgengine/router

Part of unforking our winipcfg-go and using upstream (#760), move our
additions into our repo. (We might upstream them later if upstream has
interest)

Originally these were:

@apenwarr: "Add ifc.SyncAddresses() and SyncRoutes()."
609dcf2df5

@bradfitz: "winipcfg: make Interface.AddRoutes do as much as possible, return combined error"
e9f93d53f3

@bradfitz: "prevent unnecessary Interface.SyncAddresses work; normalize IPNets in deltaNets"
decb9ee8e1

wgengine/router/ifconfig_windows_test.go

@@ -5,8 +5,10 @@
 package router
 
 import (
+	"fmt"
 	"math/rand"
 	"net"
+	"strings"
 	"testing"
 
 	winipcfg "github.com/tailscale/winipcfg-go"
@@ -95,3 +97,144 @@ func TestRouteLessConsistent(t *testing.T) {
 		}
 	}
 }
+
+func equalNetIPs(a, b []*net.IPNet) bool {
+	if len(a) != len(b) {
+		return false
+	}
+	for i := range a {
+		if netCompare(*a[i], *b[i]) != 0 {
+			return false
+		}
+	}
+	return true
+}
+
+func ipnet4(ip string, bits int) *net.IPNet {
+	return &net.IPNet{
+		IP:   net.ParseIP(ip),
+		Mask: net.CIDRMask(bits, 32),
+	}
+}
+
+// each cidr can end in "[4]" to mean To4 form.
+func nets(cidrs ...string) (ret []*net.IPNet) {
+	for _, s := range cidrs {
+		to4 := strings.HasSuffix(s, "[4]")
+		if to4 {
+			s = strings.TrimSuffix(s, "[4]")
+		}
+		ip, ipNet, err := net.ParseCIDR(s)
+		if err != nil {
+			panic(fmt.Sprintf("Bogus CIDR %q in test", s))
+		}
+		if to4 {
+			ip = ip.To4()
+		}
+		ipNet.IP = ip
+		ret = append(ret, ipNet)
+	}
+	return
+}
+
+func TestDeltaNets(t *testing.T) {
+	tests := []struct {
+		a, b             []*net.IPNet
+		wantAdd, wantDel []*net.IPNet
+	}{
+		{
+			a:       nets("1.2.3.4/24", "1.2.3.4/31", "1.2.3.3/32", "10.0.1.1/32", "100.0.1.1/32"),
+			b:       nets("10.0.1.1/32", "100.0.2.1/32", "1.2.3.3/32", "1.2.3.4/24"),
+			wantAdd: nets("100.0.2.1/32"),
+			wantDel: nets("1.2.3.4/31", "100.0.1.1/32"),
+		},
+		{
+			a:       nets("fe80::99d0:ec2d:b2e7:536b/64", "100.84.36.11/32"),
+			b:       nets("100.84.36.11/32"),
+			wantDel: nets("fe80::99d0:ec2d:b2e7:536b/64"),
+		},
+		{
+			a:       nets("100.84.36.11/32", "fe80::99d0:ec2d:b2e7:536b/64"),
+			b:       nets("100.84.36.11/32"),
+			wantDel: nets("fe80::99d0:ec2d:b2e7:536b/64"),
+		},
+		{
+			a:       nets("100.84.36.11/32", "fe80::99d0:ec2d:b2e7:536b/64"),
+			b:       nets("100.84.36.11/32[4]"),
+			wantDel: nets("fe80::99d0:ec2d:b2e7:536b/64"),
+		},
+		{
+			a: excludeIPv6LinkLocal(nets("100.84.36.11/32", "fe80::99d0:ec2d:b2e7:536b/64")),
+			b: nets("100.84.36.11/32"),
+		},
+		{
+			a: []*net.IPNet{
+				{
+					IP:   net.ParseIP("1.2.3.4"),
+					Mask: net.IPMask{0xff, 0xff, 0xff, 0xff},
+				},
+			},
+			b: []*net.IPNet{
+				{
+					IP:   net.ParseIP("1.2.3.4"),
+					Mask: net.IPMask{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff},
+				},
+			},
+		},
+	}
+	for i, tt := range tests {
+		add, del := deltaNets(tt.a, tt.b)
+		if !equalNetIPs(add, tt.wantAdd) {
+			t.Errorf("[%d] add:\n  got: %v\n want: %v\n", i, add, tt.wantAdd)
+		}
+		if !equalNetIPs(del, tt.wantDel) {
+			t.Errorf("[%d] del:\n  got: %v\n want: %v\n", i, del, tt.wantDel)
+		}
+	}
+}
+
+func equalRouteDatas(a, b []*winipcfg.RouteData) bool {
+	if len(a) != len(b) {
+		return false
+	}
+	for i := range a {
+		if routeDataCompare(a[i], b[i]) != 0 {
+			return false
+		}
+	}
+	return true
+}
+
+func TestDeltaRouteData(t *testing.T) {
+	var h0 net.IP
+	h1 := net.ParseIP("99.99.99.99")
+	h2 := net.ParseIP("99.99.9.99")
+
+	a := []*winipcfg.RouteData{
+		{*ipnet4("1.2.3.4", 32), h0, 1},
+		{*ipnet4("1.2.3.4", 24), h1, 2},
+		{*ipnet4("1.2.3.4", 24), h2, 1},
+		{*ipnet4("1.2.3.5", 32), h0, 1},
+	}
+	b := []*winipcfg.RouteData{
+		{*ipnet4("1.2.3.5", 32), h0, 1},
+		{*ipnet4("1.2.3.4", 24), h1, 2},
+		{*ipnet4("1.2.3.4", 24), h2, 2},
+	}
+	add, del := deltaRouteData(a, b)
+
+	wantAdd := []*winipcfg.RouteData{
+		{*ipnet4("1.2.3.4", 24), h2, 2},
+	}
+	wantDel := []*winipcfg.RouteData{
+		{*ipnet4("1.2.3.4", 32), h0, 1},
+		{*ipnet4("1.2.3.4", 24), h2, 1},
+	}
+
+	if !equalRouteDatas(add, wantAdd) {
+		t.Errorf("add:\n   got: %v\n  want: %v\n", add, wantAdd)
+	}
+	if !equalRouteDatas(del, wantDel) {
+		t.Errorf("del:\n   got: %v\n  want: %v\n", del, wantDel)
+	}
+}