implemented BitAtPosition for IPv6

net/ip.go

@@ -182,5 +182,13 @@ func (ip IP) bitAtPositionIPv4(pos uint8) bool {
 }
 
 func (ip IP) bitAtPositionIPv6(pos uint8) bool {
-	panic("No IPv6 support yet!")
+	if pos > 128 {
+		return false
+	}
+
+	if pos <= 64 {
+		return (ip.higher & (1 << (64 - pos))) != 0
+	}
+
+	return (ip.lower & (1 << (128 - pos))) != 0
 }

net/ip_test.go

@@ -313,17 +313,41 @@ func TestBitAtPosition(t *testing.T) {
 		expected bool
 	}{
 		{
-			name:     "Bit 8 from 1.0.0.0 -> 0",
+			name:     "IPv4: Bit 8 from 1.0.0.0 -> 0",
 			input:    IPv4FromOctets(10, 0, 0, 0),
 			position: 8,
 			expected: false,
 		},
 		{
-			name:     "Bit 8 from 11.0.0.0 -> 1",
+			name:     "IPv4: Bit 8 from 11.0.0.0 -> 1",
 			input:    IPv4FromOctets(11, 0, 0, 0),
 			position: 8,
 			expected: true,
 		},
+		{
+			name:     "IPv6: Bit 16 from 2001:678:1e0:: -> 1",
+			input:    IPv6FromBlocks(0x2001, 0x678, 0x1e0, 0, 0, 0, 0, 0),
+			position: 16,
+			expected: true,
+		},
+		{
+			name:     "IPv6: Bit 17 from 2001:678:1e0:: -> 0",
+			input:    IPv6FromBlocks(0x2001, 0x678, 0x1e0, 0, 0, 0, 0, 0),
+			position: 17,
+			expected: false,
+		},
+		{
+			name:     "IPv6: Bit 113 from 2001:678:1e0::cafe -> 1",
+			input:    IPv6FromBlocks(0x2001, 0x678, 0x1e0, 0, 0, 0, 0, 0xcafe),
+			position: 113,
+			expected: true,
+		},
+		{
+			name:     "IPv6: Bit 115 from 2001:678:1e0::cafe -> 0",
+			input:    IPv6FromBlocks(0x2001, 0x678, 0x1e0, 0, 0, 0, 0, 0xcafe),
+			position: 115,
+			expected: false,
+		},
 	}
 
 	for _, test := range tests {