p2p/enode: allow DNS names in enode URLs (ethereum#18524)

p2p/enode/urlv4.go

@@ -125,15 +125,17 @@ func parseComplete(rawurl string) (*Node, error) {
 		return nil, fmt.Errorf("invalid public key (%v)", err)
 	}
 	// Parse the IP address.
-	host, port, err := net.SplitHostPort(u.Host)
+	ips, err := net.LookupIP(u.Hostname())
 	if err != nil {
-		return nil, fmt.Errorf("invalid host: %v", err)
+		return nil, err
 	}
-	if ip = net.ParseIP(host); ip == nil {
-		return nil, errors.New("invalid IP address")
+	ip = ips[0]
+	// Ensure the IP is 4 bytes long for IPv4 addresses.
+	if ipv4 := ip.To4(); ipv4 != nil {
+		ip = ipv4
 	}
 	// Parse the port numbers.
-	if tcpPort, err = strconv.ParseUint(port, 10, 16); err != nil {
+	if tcpPort, err = strconv.ParseUint(u.Port(), 10, 16); err != nil {
 		return nil, errors.New("invalid port")
 	}
 	udpPort = tcpPort

p2p/enode/urlv4_test.go

@@ -61,8 +61,8 @@ var parseNodeTests = []struct {
 	},
 	// Complete node URLs with IP address and ports
 	{
-		input:     "enode://1dd9d65c4552b5eb43d5ad55a2ee3f56c6cbc1c64a5c8d659f51fcd51bace24351232b8d7821617d2b29b54b81cdefb9b3e9c37d7fd5f63270bcc9e1a6f6a439@hostname:3",
-		wantError: `invalid IP address`,
+		input:     "enode://1dd9d65c4552b5eb43d5ad55a2ee3f56c6cbc1c64a5c8d659f51fcd51bace24351232b8d7821617d2b29b54b81cdefb9b3e9c37d7fd5f63270bcc9e1a6f6a439@invalid.:3",
+		wantError: `no such host`,
 	},
 	{
 		input:     "enode://1dd9d65c4552b5eb43d5ad55a2ee3f56c6cbc1c64a5c8d659f51fcd51bace24351232b8d7821617d2b29b54b81cdefb9b3e9c37d7fd5f63270bcc9e1a6f6a439@127.0.0.1:foo",
@@ -76,7 +76,7 @@ var parseNodeTests = []struct {
 		input: "enode://1dd9d65c4552b5eb43d5ad55a2ee3f56c6cbc1c64a5c8d659f51fcd51bace24351232b8d7821617d2b29b54b81cdefb9b3e9c37d7fd5f63270bcc9e1a6f6a439@127.0.0.1:52150",
 		wantResult: NewV4(
 			hexPubkey("1dd9d65c4552b5eb43d5ad55a2ee3f56c6cbc1c64a5c8d659f51fcd51bace24351232b8d7821617d2b29b54b81cdefb9b3e9c37d7fd5f63270bcc9e1a6f6a439"),
-			net.IP{0x7f, 0x0, 0x0, 0x1},
+			net.IP{127, 0, 0, 1},
 			52150,
 			52150,
 		),