channeldb/addr_test: add invalid TCP cases

These are invalid length IP addresses that earlier would not fail to
serialize.

channeldb/addr_test.go

@@ -14,19 +14,23 @@ type unknownAddrType struct{}
 func (t unknownAddrType) Network() string { return "unknown" }
 func (t unknownAddrType) String() string  { return "unknown" }
 
+var testIP4 = net.ParseIP("192.168.1.1")
+var testIP6 = net.ParseIP("2001:0db8:0000:0000:0000:ff00:0042:8329")
+
 var addrTests = []struct {
 	expAddr net.Addr
 	serErr  string
 }{
+	// Valid addresses.
 	{
 		expAddr: &net.TCPAddr{
-			IP:   net.ParseIP("192.168.1.1"),
+			IP:   testIP4,
 			Port: 12345,
 		},
 	},
 	{
 		expAddr: &net.TCPAddr{
-			IP:   net.ParseIP("2001:0db8:0000:0000:0000:ff00:0042:8329"),
+			IP:   testIP6,
 			Port: 65535,
 		},
 	},
@@ -42,10 +46,44 @@ var addrTests = []struct {
 			Port:         80,
 		},
 	},
+
+	// Invalid addresses.
 	{
 		expAddr: unknownAddrType{},
 		serErr:  ErrUnknownAddressType.Error(),
 	},
+	{
+		expAddr: &net.TCPAddr{
+			// Remove last byte of IPv4 address.
+			IP:   testIP4[:len(testIP4)-1],
+			Port: 12345,
+		},
+		serErr: "unable to encode",
+	},
+	{
+		expAddr: &net.TCPAddr{
+			// Add an extra byte of IPv4 address.
+			IP:   append(testIP4, 0xff),
+			Port: 12345,
+		},
+		serErr: "unable to encode",
+	},
+	{
+		expAddr: &net.TCPAddr{
+			// Remove last byte of IPv6 address.
+			IP:   testIP6[:len(testIP6)-1],
+			Port: 65535,
+		},
+		serErr: "unable to encode",
+	},
+	{
+		expAddr: &net.TCPAddr{
+			// Add an extra byte to the IPv6 address.
+			IP:   append(testIP6, 0xff),
+			Port: 65535,
+		},
+		serErr: "unable to encode",
+	},
 }
 
 // TestAddrSerialization tests that the serialization method used by channeldb