Fix index-out-of-bound bug when inserting network that shares direct branch...

Fix index-out-of-bound bug when inserting network that shares direct branch point with single-IP (leaf) network, closes #3

trie.go

@@ -188,7 +188,7 @@ func (p *prefixTrie) insert(network rnet.Network, entry RangerEntry) error {
 	if err != nil {
 		return err
 	}
-	if lcb-1 > child.targetBitPosition() {
+	if int(lcb) > child.targetBitPosition()+1 {
 		child = newPathprefixTrie(network, p.totalNumberOfBits()-lcb)
 		err := p.insertPrefix(bit, child)
 		if err != nil {
@@ -259,12 +259,14 @@ func (p *prefixTrie) totalNumberOfBits() uint {
 	return rnet.BitsPerUint32 * uint(len(p.network.Number))
 }
 
-func (p *prefixTrie) targetBitPosition() uint {
-	return p.totalNumberOfBits() - p.numBitsSkipped - 1
+func (p *prefixTrie) targetBitPosition() int {
+	return int(p.totalNumberOfBits()-p.numBitsSkipped) - 1
 }
 
 func (p *prefixTrie) targetBitFromIP(n rnet.NetworkNumber) (uint32, error) {
-	return n.Bit(p.targetBitPosition())
+	// This is a safe uint boxing of int since we should never attempt to get
+	// target bit at a negative position.
+	return n.Bit(uint(p.targetBitPosition()))
 }
 
 func (p *prefixTrie) hasEntry() bool {

trie_test.go

@@ -16,12 +16,30 @@ func TestPrefixTrieInsert(t *testing.T) {
 		name                         string
 	}{
 		{rnet.IPv4, []string{"192.168.0.1/24"}, []string{"192.168.0.1/24"}, "basic insert"},
+		{
+			rnet.IPv4,
+			[]string{"1.2.3.4/32", "1.2.3.5/32"},
+			[]string{"1.2.3.4/32", "1.2.3.5/32"},
+			"single ip IPv4 network insert",
+		},
+		{
+			rnet.IPv6,
+			[]string{"0::1/128", "0::2/128"},
+			[]string{"0::1/128", "0::2/128"},
+			"single ip IPv6 network insert",
+		},
 		{
 			rnet.IPv4,
 			[]string{"192.168.0.1/16", "192.168.0.1/24"},
 			[]string{"192.168.0.1/16", "192.168.0.1/24"},
 			"in order insert",
 		},
+		{
+			rnet.IPv4,
+			[]string{"192.168.0.1/32", "192.168.0.1/32"},
+			[]string{"192.168.0.1/32"},
+			"duplicate network insert",
+		},
 		{
 			rnet.IPv4,
 			[]string{"192.168.0.1/24", "192.168.0.1/16"},
@@ -97,6 +115,22 @@ func TestPrefixTrieRemove(t *testing.T) {
 			[]string{},
 			"basic remove",
 		},
+		{
+			rnet.IPv4,
+			[]string{"1.2.3.4/32", "1.2.3.5/32"},
+			[]string{"1.2.3.5/32"},
+			[]string{"1.2.3.5/32"},
+			[]string{"1.2.3.4/32"},
+			"single ip IPv4 network remove",
+		},
+		{
+			rnet.IPv4,
+			[]string{"0::1/128", "0::2/128"},
+			[]string{"0::2/128"},
+			[]string{"0::2/128"},
+			[]string{"0::1/128"},
+			"single ip IPv6 network remove",
+		},
 		{
 			rnet.IPv4,
 			[]string{"192.168.0.1/24", "192.168.0.1/25", "192.168.0.1/26"},