Maint: rework IPIsPrivate in internal/routing

internal/routing/reader.go

@@ -265,24 +265,6 @@ func (r *Routing) VPNLocalGatewayIP(vpnIntf string) (ip net.IP, err error) {
 }
 
 func IPIsPrivate(ip net.IP) bool {
-	if ip.IsLoopback() || ip.IsLinkLocalUnicast() || ip.IsLinkLocalMulticast() {
+	return ip.IsPrivate() || ip.IsLoopback() ||
-		return true
+		ip.IsLinkLocalUnicast() || ip.IsLinkLocalMulticast()
-	}
-	privateCIDRBlocks := [8]string{
-		"127.0.0.0/8",    // localhost
-		"10.0.0.0/8",     // 24-bit block
-		"172.16.0.0/12",  // 20-bit block
-		"192.168.0.0/16", // 16-bit block
-		"169.254.0.0/16", // link local address
-		"::1/128",        // localhost IPv6
-		"fc00::/7",       // unique local address IPv6
-		"fe80::/10",      // link local address IPv6
-	}
-	for i := range privateCIDRBlocks {
-		_, CIDR, _ := net.ParseCIDR(privateCIDRBlocks[i])
-		if CIDR.Contains(ip) {
-			return true
-		}
-	}
-	return false
 }

internal/routing/reader_test.go

@@ -0,0 +1,98 @@
+package routing
+
+import (
+	"net"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func Test_IPIsPrivate(t *testing.T) {
+	t.Parallel()
+
+	testCases := map[string]struct {
+		ipString  string
+		isPrivate bool
+	}{
+		"loopback 127.0.0.1": {
+			ipString:  "127.0.0.1",
+			isPrivate: true,
+		},
+		"loopback 127.0.0.10": {
+			ipString:  "127.0.0.10",
+			isPrivate: true,
+		},
+		"loopback ::1": {
+			ipString:  "::1",
+			isPrivate: true,
+		},
+		"private 10.0.0.1": {
+			ipString:  "10.0.0.1",
+			isPrivate: true,
+		},
+		"private 10.255.255.255": {
+			ipString:  "10.255.255.255",
+			isPrivate: true,
+		},
+		"private 172.16.0.1": {
+			ipString:  "172.16.0.1",
+			isPrivate: true,
+		},
+		"private 172.31.255.255": {
+			ipString:  "172.31.255.255",
+			isPrivate: true,
+		},
+		"private 192.168.0.0": {
+			ipString:  "192.168.0.0",
+			isPrivate: true,
+		},
+		"private 192.168.255.255": {
+			ipString:  "192.168.255.255",
+			isPrivate: true,
+		},
+		"private fc00::": {
+			ipString:  "fc00::",
+			isPrivate: true,
+		},
+		"private fc00::af": {
+			ipString:  "fc00::af",
+			isPrivate: true,
+		},
+		"local unicast 169.254.0.0": {
+			ipString:  "169.254.0.0",
+			isPrivate: true,
+		},
+		"local unicast 169.254.255.255": {
+			ipString:  "169.254.255.255",
+			isPrivate: true,
+		},
+		"local unicast fe80::": {
+			ipString:  "fe80::",
+			isPrivate: true,
+		},
+		"local unicast fe80::ae": {
+			ipString:  "fe80::ae",
+			isPrivate: true,
+		},
+		"public IPv4": {
+			ipString: "11.5.6.7",
+		},
+		"public IPv6": {
+			ipString: "af6d::",
+		},
+	}
+	for name, testCase := range testCases {
+		testCase := testCase
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
+
+			ip := net.ParseIP(testCase.ipString)
+			require.NotNil(t, ip)
+
+			isPrivate := IPIsPrivate(ip)
+
+			assert.Equal(t, testCase.isPrivate, isPrivate)
+		})
+	}
+}