+ rewrites: support deeper level wildcards - select the more specific one

dnsfilter/dnsfilter_test.go

@@ -532,96 +532,6 @@ func TestClientSettings(t *testing.T) {
 	assert.True(t, r.IsFiltered && r.Reason == FilteredBlockedService)
 }
 
-func TestRewrites(t *testing.T) {
-	d := Dnsfilter{}
-	// CNAME, A, AAAA
-	d.Rewrites = []RewriteEntry{
-		RewriteEntry{"somecname", "somehost.com", 0, nil},
-		RewriteEntry{"somehost.com", "0.0.0.0", 0, nil},
-
-		RewriteEntry{"host.com", "1.2.3.4", 0, nil},
-		RewriteEntry{"host.com", "1.2.3.5", 0, nil},
-		RewriteEntry{"host.com", "1:2:3::4", 0, nil},
-		RewriteEntry{"www.host.com", "host.com", 0, nil},
-	}
-	d.prepareRewrites()
-	r := d.processRewrites("host2.com")
-	assert.Equal(t, NotFilteredNotFound, r.Reason)
-
-	r = d.processRewrites("www.host.com")
-	assert.Equal(t, ReasonRewrite, r.Reason)
-	assert.Equal(t, "host.com", r.CanonName)
-	assert.True(t, len(r.IPList) == 3)
-	assert.True(t, r.IPList[0].Equal(net.ParseIP("1.2.3.4")))
-	assert.True(t, r.IPList[1].Equal(net.ParseIP("1.2.3.5")))
-	assert.True(t, r.IPList[2].Equal(net.ParseIP("1:2:3::4")))
-
-	// wildcard
-	d.Rewrites = []RewriteEntry{
-		RewriteEntry{"host.com", "1.2.3.4", 0, nil},
-		RewriteEntry{"*.host.com", "1.2.3.5", 0, nil},
-	}
-	d.prepareRewrites()
-	r = d.processRewrites("host.com")
-	assert.Equal(t, ReasonRewrite, r.Reason)
-	assert.True(t, r.IPList[0].Equal(net.ParseIP("1.2.3.4")))
-
-	r = d.processRewrites("www.host.com")
-	assert.Equal(t, ReasonRewrite, r.Reason)
-	assert.True(t, r.IPList[0].Equal(net.ParseIP("1.2.3.5")))
-
-	r = d.processRewrites("www.host2.com")
-	assert.Equal(t, NotFilteredNotFound, r.Reason)
-
-	// override a wildcard
-	d.Rewrites = []RewriteEntry{
-		RewriteEntry{"a.host.com", "1.2.3.4", 0, nil},
-		RewriteEntry{"*.host.com", "1.2.3.5", 0, nil},
-	}
-	d.prepareRewrites()
-	r = d.processRewrites("a.host.com")
-	assert.Equal(t, ReasonRewrite, r.Reason)
-	assert.True(t, len(r.IPList) == 1)
-	assert.True(t, r.IPList[0].Equal(net.ParseIP("1.2.3.4")))
-
-	// wildcard + CNAME
-	d.Rewrites = []RewriteEntry{
-		RewriteEntry{"host.com", "1.2.3.4", 0, nil},
-		RewriteEntry{"*.host.com", "host.com", 0, nil},
-	}
-	d.prepareRewrites()
-	r = d.processRewrites("www.host.com")
-	assert.Equal(t, ReasonRewrite, r.Reason)
-	assert.Equal(t, "host.com", r.CanonName)
-	assert.True(t, r.IPList[0].Equal(net.ParseIP("1.2.3.4")))
-
-	// 2 CNAMEs
-	d.Rewrites = []RewriteEntry{
-		RewriteEntry{"b.host.com", "a.host.com", 0, nil},
-		RewriteEntry{"a.host.com", "host.com", 0, nil},
-		RewriteEntry{"host.com", "1.2.3.4", 0, nil},
-	}
-	d.prepareRewrites()
-	r = d.processRewrites("b.host.com")
-	assert.Equal(t, ReasonRewrite, r.Reason)
-	assert.Equal(t, "host.com", r.CanonName)
-	assert.True(t, len(r.IPList) == 1)
-	assert.True(t, r.IPList[0].Equal(net.ParseIP("1.2.3.4")))
-
-	// 2 CNAMEs + wildcard
-	d.Rewrites = []RewriteEntry{
-		RewriteEntry{"b.host.com", "a.host.com", 0, nil},
-		RewriteEntry{"a.host.com", "x.somehost.com", 0, nil},
-		RewriteEntry{"*.somehost.com", "1.2.3.4", 0, nil},
-	}
-	d.prepareRewrites()
-	r = d.processRewrites("b.host.com")
-	assert.Equal(t, ReasonRewrite, r.Reason)
-	assert.Equal(t, "x.somehost.com", r.CanonName)
-	assert.True(t, len(r.IPList) == 1)
-	assert.True(t, r.IPList[0].Equal(net.ParseIP("1.2.3.4")))
-}
-
 func prepareTestDir() string {
 	const dir = "./agh-test"
 	_ = os.RemoveAll(dir)

dnsfilter/rewrites.go

@@ -42,7 +42,10 @@ func (a rewritesArray) Len() int { return len(a) }
 
 func (a rewritesArray) Swap(i, j int) { a[i], a[j] = a[j], a[i] }
 
-// Priority: CNAME, A/AAAA;  exact, wildcard.
+// Priority:
+//  . CNAME > A/AAAA;
+//  . exact > wildcard;
+//  . higher level wildcard > lower level wildcard
 func (a rewritesArray) Less(i, j int) bool {
 	if a[i].Type == dns.TypeCNAME && a[j].Type != dns.TypeCNAME {
 		return false
@@ -50,13 +53,18 @@ func (a rewritesArray) Less(i, j int) bool {
 		return true
 	}
 
-	if isWildcard(a[i].Domain) && !isWildcard(a[j].Domain) {
+	if isWildcard(a[i].Domain) {
+		if !isWildcard(a[j].Domain) {
 			return false
-	} else if !isWildcard(a[i].Domain) && isWildcard(a[j].Domain) {
+		}
+	} else {
+		if isWildcard(a[j].Domain) {
 			return true
 		}
+	}
 
-	return i < j
+	// both are wildcards
+	return len(a[i].Domain) > len(a[j].Domain)
 }
 
 // Prepare entry for use
@@ -86,6 +94,7 @@ func (d *Dnsfilter) prepareRewrites() {
 // Get the list of matched rewrite entries.
 // Priority: CNAME, A/AAAA;  exact, wildcard.
 // If matched exactly, don't return wildcard entries.
+// If matched by several wildcards, select the more specific one
 func findRewrites(a []RewriteEntry, host string) []RewriteEntry {
 	rr := rewritesArray{}
 	for _, r := range a {
@@ -111,7 +120,10 @@ func findRewrites(a []RewriteEntry, host string) []RewriteEntry {
 				break
 			}
 		}
+	} else {
+		rr = rr[:1]
 	}
+
 	return rr
 }
 

dnsfilter/rewrites_test.go

@@ -0,0 +1,127 @@
+package dnsfilter
+
+import (
+	"net"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestRewrites(t *testing.T) {
+	d := Dnsfilter{}
+	// CNAME, A, AAAA
+	d.Rewrites = []RewriteEntry{
+		RewriteEntry{"somecname", "somehost.com", 0, nil},
+		RewriteEntry{"somehost.com", "0.0.0.0", 0, nil},
+
+		RewriteEntry{"host.com", "1.2.3.4", 0, nil},
+		RewriteEntry{"host.com", "1.2.3.5", 0, nil},
+		RewriteEntry{"host.com", "1:2:3::4", 0, nil},
+		RewriteEntry{"www.host.com", "host.com", 0, nil},
+	}
+	d.prepareRewrites()
+	r := d.processRewrites("host2.com")
+	assert.Equal(t, NotFilteredNotFound, r.Reason)
+
+	r = d.processRewrites("www.host.com")
+	assert.Equal(t, ReasonRewrite, r.Reason)
+	assert.Equal(t, "host.com", r.CanonName)
+	assert.True(t, len(r.IPList) == 3)
+	assert.True(t, r.IPList[0].Equal(net.ParseIP("1.2.3.4")))
+	assert.True(t, r.IPList[1].Equal(net.ParseIP("1.2.3.5")))
+	assert.True(t, r.IPList[2].Equal(net.ParseIP("1:2:3::4")))
+
+	// wildcard
+	d.Rewrites = []RewriteEntry{
+		RewriteEntry{"host.com", "1.2.3.4", 0, nil},
+		RewriteEntry{"*.host.com", "1.2.3.5", 0, nil},
+	}
+	d.prepareRewrites()
+	r = d.processRewrites("host.com")
+	assert.Equal(t, ReasonRewrite, r.Reason)
+	assert.True(t, r.IPList[0].Equal(net.ParseIP("1.2.3.4")))
+
+	r = d.processRewrites("www.host.com")
+	assert.Equal(t, ReasonRewrite, r.Reason)
+	assert.True(t, r.IPList[0].Equal(net.ParseIP("1.2.3.5")))
+
+	r = d.processRewrites("www.host2.com")
+	assert.Equal(t, NotFilteredNotFound, r.Reason)
+
+	// override a wildcard
+	d.Rewrites = []RewriteEntry{
+		RewriteEntry{"a.host.com", "1.2.3.4", 0, nil},
+		RewriteEntry{"*.host.com", "1.2.3.5", 0, nil},
+	}
+	d.prepareRewrites()
+	r = d.processRewrites("a.host.com")
+	assert.Equal(t, ReasonRewrite, r.Reason)
+	assert.True(t, len(r.IPList) == 1)
+	assert.True(t, r.IPList[0].Equal(net.ParseIP("1.2.3.4")))
+
+	// wildcard + CNAME
+	d.Rewrites = []RewriteEntry{
+		RewriteEntry{"host.com", "1.2.3.4", 0, nil},
+		RewriteEntry{"*.host.com", "host.com", 0, nil},
+	}
+	d.prepareRewrites()
+	r = d.processRewrites("www.host.com")
+	assert.Equal(t, ReasonRewrite, r.Reason)
+	assert.Equal(t, "host.com", r.CanonName)
+	assert.True(t, r.IPList[0].Equal(net.ParseIP("1.2.3.4")))
+
+	// 2 CNAMEs
+	d.Rewrites = []RewriteEntry{
+		RewriteEntry{"b.host.com", "a.host.com", 0, nil},
+		RewriteEntry{"a.host.com", "host.com", 0, nil},
+		RewriteEntry{"host.com", "1.2.3.4", 0, nil},
+	}
+	d.prepareRewrites()
+	r = d.processRewrites("b.host.com")
+	assert.Equal(t, ReasonRewrite, r.Reason)
+	assert.Equal(t, "host.com", r.CanonName)
+	assert.True(t, len(r.IPList) == 1)
+	assert.True(t, r.IPList[0].Equal(net.ParseIP("1.2.3.4")))
+
+	// 2 CNAMEs + wildcard
+	d.Rewrites = []RewriteEntry{
+		RewriteEntry{"b.host.com", "a.host.com", 0, nil},
+		RewriteEntry{"a.host.com", "x.somehost.com", 0, nil},
+		RewriteEntry{"*.somehost.com", "1.2.3.4", 0, nil},
+	}
+	d.prepareRewrites()
+	r = d.processRewrites("b.host.com")
+	assert.Equal(t, ReasonRewrite, r.Reason)
+	assert.Equal(t, "x.somehost.com", r.CanonName)
+	assert.True(t, len(r.IPList) == 1)
+	assert.True(t, r.IPList[0].Equal(net.ParseIP("1.2.3.4")))
+}
+
+func TestRewritesLevels(t *testing.T) {
+	d := Dnsfilter{}
+	// exact host, wildcard L2, wildcard L3
+	d.Rewrites = []RewriteEntry{
+		RewriteEntry{"host.com", "1.1.1.1", 0, nil},
+		RewriteEntry{"*.host.com", "2.2.2.2", 0, nil},
+		RewriteEntry{"*.sub.host.com", "3.3.3.3", 0, nil},
+	}
+	d.prepareRewrites()
+
+	// match exact
+	r := d.processRewrites("host.com")
+	assert.Equal(t, ReasonRewrite, r.Reason)
+	assert.Equal(t, 1, len(r.IPList))
+	assert.Equal(t, "1.1.1.1", r.IPList[0].String())
+
+	// match L2
+	r = d.processRewrites("sub.host.com")
+	assert.Equal(t, ReasonRewrite, r.Reason)
+	assert.Equal(t, 1, len(r.IPList))
+	assert.Equal(t, "2.2.2.2", r.IPList[0].String())
+
+	// match L3
+	r = d.processRewrites("my.sub.host.com")
+	assert.Equal(t, ReasonRewrite, r.Reason)
+	assert.Equal(t, 1, len(r.IPList))
+	assert.Equal(t, "3.3.3.3", r.IPList[0].String())
+}