Feature(dns): support custom hosts

component/domain-trie/node.go

@@ -0,0 +1,26 @@
+package trie
+
+// Node is the trie's node
+type Node struct {
+	Data     interface{}
+	children map[string]*Node
+}
+
+func (n *Node) getChild(s string) *Node {
+	return n.children[s]
+}
+
+func (n *Node) hasChild(s string) bool {
+	return n.getChild(s) != nil
+}
+
+func (n *Node) addChild(s string, child *Node) {
+	n.children[s] = child
+}
+
+func newNode(data interface{}) *Node {
+	return &Node{
+		Data:     data,
+		children: map[string]*Node{},
+	}
+}

component/domain-trie/tire.go

@@ -0,0 +1,84 @@
+package trie
+
+import (
+	"errors"
+	"strings"
+)
+
+const (
+	wildcard   = "*"
+	domainStep = "."
+)
+
+var (
+	// ErrInvalidDomain means insert domain is invalid
+	ErrInvalidDomain = errors.New("invalid domain")
+)
+
+// Trie contains the main logic for adding and searching nodes for domain segments.
+// support wildcard domain (e.g *.google.com)
+type Trie struct {
+	root *Node
+}
+
+// Insert adds a node to the trie.
+// Support
+// 1. www.example.com
+// 2. *.example.com
+// 3. subdomain.*.example.com
+func (t *Trie) Insert(domain string, data interface{}) error {
+	parts := strings.Split(domain, domainStep)
+	if len(parts) < 2 {
+		return ErrInvalidDomain
+	}
+
+	node := t.root
+	// reverse storage domain part to save space
+	for i := len(parts) - 1; i >= 0; i-- {
+		part := parts[i]
+		if !node.hasChild(part) {
+			node.addChild(part, newNode(nil))
+		}
+
+		node = node.getChild(part)
+	}
+
+	node.Data = data
+	return nil
+}
+
+// Search is the most important part of the Trie.
+// Priority as:
+// 1. static part
+// 2. wildcard domain
+func (t *Trie) Search(domain string) *Node {
+	parts := strings.Split(domain, domainStep)
+	if len(parts) < 2 {
+		return nil
+	}
+
+	n := t.root
+	for i := len(parts) - 1; i >= 0; i-- {
+		part := parts[i]
+
+		var child *Node
+		if !n.hasChild(part) {
+			if !n.hasChild(wildcard) {
+				return nil
+			}
+
+			child = n.getChild(wildcard)
+		} else {
+			child = n.getChild(part)
+		}
+
+		n = child
+	}
+
+	return n
+}
+
+// New returns a new, empty Trie.
+func New() *Trie {
+	return &Trie{root: newNode(nil)}
+}

component/domain-trie/trie_test.go

@@ -0,0 +1,69 @@
+package trie
+
+import (
+	"net"
+	"testing"
+)
+
+func TestTrie_Basic(t *testing.T) {
+	tree := New()
+	domains := []string{
+		"example.com",
+		"google.com",
+	}
+
+	for _, domain := range domains {
+		tree.Insert(domain, net.ParseIP("127.0.0.1"))
+	}
+
+	node := tree.Search("example.com")
+	if node == nil {
+		t.Error("should not recv nil")
+	}
+
+	if !node.Data.(net.IP).Equal(net.IP{127, 0, 0, 1}) {
+		t.Error("should equal 127.0.0.1")
+	}
+}
+
+func TestTrie_Wildcard(t *testing.T) {
+	tree := New()
+	domains := []string{
+		"*.example.com",
+		"sub.*.example.com",
+		"*.dev",
+	}
+
+	for _, domain := range domains {
+		tree.Insert(domain, nil)
+	}
+
+	if tree.Search("sub.example.com") == nil {
+		t.Error("should not recv nil")
+	}
+
+	if tree.Search("sub.foo.example.com") == nil {
+		t.Error("should not recv nil")
+	}
+
+	if tree.Search("foo.sub.example.com") != nil {
+		t.Error("should recv nil")
+	}
+
+	if tree.Search("foo.example.dev") != nil {
+		t.Error("should recv nil")
+	}
+}
+
+func TestTrie_Boundary(t *testing.T) {
+	tree := New()
+	tree.Insert("*.dev", nil)
+
+	if err := tree.Insert("com", nil); err == nil {
+		t.Error("should recv err")
+	}
+
+	if tree.Search("dev") != nil {
+		t.Error("should recv nil")
+	}
+}