Fix bug in covering logic and add new Covers() method for network.

Signed-off-by: Rob Adams <readams@readams.net>

brute.go

@@ -98,7 +98,11 @@ func (b *bruteRanger) CoveredNetworks(network net.IPNet) ([]RangerEntry, error)
 	var results []RangerEntry
 	for _, entry := range entries {
 		entrynetwork := entry.Network()
-		if network.Contains(entrynetwork.IP) {
+
+		searchMaskSize, _ := network.Mask.Size()
+		entryMaskSize, _ := entrynetwork.Mask.Size()
+
+		if network.Contains(entrynetwork.IP) && searchMaskSize <= entryMaskSize {
 			results = append(results, entry)
 		}
 	}

net/ip.go

@@ -208,6 +208,13 @@ func (n Network) Contains(nn NetworkNumber) bool {
 	return true
 }
 
+// Contains returns true if Network covers o, false otherwise
+func (n Network) Covers(o Network) bool {
+	nMaskSize, _ := n.IPNet.Mask.Size()
+	oMaskSize, _ := o.IPNet.Mask.Size()
+	return n.Contains(o.Number) && nMaskSize <= oMaskSize
+}
+
 // LeastCommonBitPosition returns the smallest position of the preceding common
 // bits of the 2 networks, and returns an error ErrNoGreatestCommonBit
 // if the two network number diverges from the first bit.

net/ip_test.go

@@ -412,6 +412,31 @@ func TestPreviousIP(t *testing.T) {
 	}
 }
 
+func TestNetworkCovers(t *testing.T) {
+	cases := []struct {
+		network string
+		covers  string
+		result  bool
+		name    string
+	}{
+		{"10.0.0.0/24", "10.0.0.1/25", true, "contains"},
+		{"10.0.0.0/24", "11.0.0.1/25", false, "not contains"},
+		{"10.0.0.0/16", "10.0.0.0/15", false, "prefix false"},
+		{"10.0.0.0/15", "10.0.0.0/16", true, "prefix true"},
+		{"10.0.0.0/15", "10.0.0.0/15", true, "same"},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			_, n, _ := net.ParseCIDR(tc.network)
+			network := NewNetwork(*n)
+			_, n, _ = net.ParseCIDR(tc.covers)
+			covers := NewNetwork(*n)
+			assert.Equal(t, tc.result, network.Covers(covers))
+		})
+	}
+}
+
 /*
  *********************************
  Benchmarking ip manipulations.

trie.go

@@ -186,7 +186,7 @@ func (p *prefixTrie) containingNetworks(number rnet.NetworkNumber) ([]RangerEntr
 
 func (p *prefixTrie) coveredNetworks(network rnet.Network) ([]RangerEntry, error) {
 	var results []RangerEntry
-	if p.hasEntry() && network.Contains(p.network.Number) {
+	if p.hasEntry() && network.Covers(p.network) {
 		results = []RangerEntry{p.entry}
 	}
 	if p.targetBitPosition() < 0 {

trie_test.go

@@ -404,6 +404,15 @@ var coveredNetworkTests = []coveredNetworkTest{
 		[]string{"192.168.0.0/24", "192.168.1.1/32"},
 		"path not taken",
 	},
+	{
+		rnet.IPv4,
+		[]string{
+			"192.168.0.0/15",
+		},
+		"192.168.0.0/16",
+		nil,
+		"only masks different",
+	},
 }
 
 func TestPrefixTrieCoveredNetworks(t *testing.T) {