From 806047488ad3f6f9c8453a3efd08c9065f549538 Mon Sep 17 00:00:00 2001
From: gVisor bot <gvisor-bot@google.com>
Date: Wed, 24 Jun 2020 18:41:23 +0800
Subject: [PATCH] Fix: domain trie should backtrack to parent if match fail
 (#758)

---
 component/trie/domain.go      | 58 +++++++++++++++--------------------
 component/trie/domain_test.go |  5 +++
 2 files changed, 30 insertions(+), 33 deletions(-)

diff --git a/component/trie/domain.go b/component/trie/domain.go
index e8dcf213..8df22792 100644
--- a/component/trie/domain.go
+++ b/component/trie/domain.go
@@ -96,39 +96,7 @@ func (t *DomainTrie) Search(domain string) *Node {
 		return nil
 	}
 
-	n := t.root
-	var dotWildcardNode *Node
-	var wildcardNode *Node
-	for i := len(parts) - 1; i >= 0; i-- {
-		part := parts[i]
-
-		if node := n.getChild(dotWildcard); node != nil {
-			dotWildcardNode = node
-		}
-
-		child := n.getChild(part)
-		if child == nil && wildcardNode != nil {
-			child = wildcardNode.getChild(part)
-		}
-		wildcardNode = n.getChild(wildcard)
-
-		n = child
-		if n == nil {
-			n = wildcardNode
-			wildcardNode = nil
-		}
-
-		if n == nil {
-			break
-		}
-	}
-
-	if n == nil {
-		if dotWildcardNode != nil {
-			return dotWildcardNode
-		}
-		return nil
-	}
+	n := t.search(t.root, parts)
 
 	if n.Data == nil {
 		return nil
@@ -137,6 +105,30 @@ func (t *DomainTrie) Search(domain string) *Node {
 	return n
 }
 
+func (t *DomainTrie) search(node *Node, parts []string) *Node {
+	if len(parts) == 0 {
+		return node
+	}
+
+	if c := node.getChild(parts[len(parts)-1]); c != nil {
+		if n := t.search(c, parts[:len(parts)-1]); n != nil {
+			return n
+		}
+	}
+
+	if c := node.getChild(wildcard); c != nil {
+		if n := t.search(c, parts[:len(parts)-1]); n != nil {
+			return n
+		}
+	}
+
+	if c := node.getChild(dotWildcard); c != nil {
+		return c
+	}
+
+	return nil
+}
+
 // New returns a new, empty Trie.
 func New() *DomainTrie {
 	return &DomainTrie{root: newNode(nil)}
diff --git a/component/trie/domain_test.go b/component/trie/domain_test.go
index 38b347e1..3e150717 100644
--- a/component/trie/domain_test.go
+++ b/component/trie/domain_test.go
@@ -39,6 +39,10 @@ func TestTrie_Wildcard(t *testing.T) {
 		".example.net",
 		".apple.*",
 		"+.foo.com",
+		"+.stun.*.*",
+		"+.stun.*.*.*",
+		"+.stun.*.*.*.*",
+		"stun.l.google.com",
 	}
 
 	for _, domain := range domains {
@@ -52,6 +56,7 @@ func TestTrie_Wildcard(t *testing.T) {
 	assert.NotNil(t, tree.Search("test.apple.com"))
 	assert.NotNil(t, tree.Search("test.foo.com"))
 	assert.NotNil(t, tree.Search("foo.com"))
+	assert.NotNil(t, tree.Search("global.stun.website.com"))
 	assert.Nil(t, tree.Search("foo.sub.example.com"))
 	assert.Nil(t, tree.Search("foo.example.dev"))
 	assert.Nil(t, tree.Search("example.com"))