fixed naive impl, added more tests

proxy.go

@@ -529,26 +529,21 @@ func isIPv6(address string) bool {
 	ip := net.ParseIP(address)
 	return ip != nil && ip.To4() == nil
 }
+
 func parseHost(request *http.Request) string {
-	//ignore conversion errors
-	if isIPv6(request.Host) {
-		return request.Host
-	}
-	al := strings.Split(request.Host, colon)
-	fmt.Println("Number of colons", len(al))
-	if len(al) == 9 {
-		host := strings.Join(al[:8], ":")
-		fmt.Println("Host - ", host)
-		if isIPv6(host) {
-			return host
-		}
-		return request.Host
+	host := request.Host
+	hostElements := strings.Split(host, ":")
+	//trim port for ipv4
+	if len(hostElements) == 2 {
+		host = hostElements[0]
 	}
-	if len(al) > 2 {
-		return request.Host
+
+	//trim port for ipv6
+	if strings.Contains(host, "]") {
+		host = host[:strings.LastIndex(host, "]")+1]
 	}
-	al2, _ := idna.ToASCII(al[0])
-	return al2
+	host, _ = idna.ToASCII(host)
+	return host
 }
 
 func parseMethod(request *http.Request) string {

proxy_test.go

@@ -475,7 +475,15 @@ func TestParseHost(t *testing.T) {
 		{name: "ipv4 with port", url: "http://127.0.0.1:8080/path", host: "127.0.0.1"},
 		{name: "simple ipv6", url: "http://::1/path", host: "::1"},
 		{name: "simple ipv6 in brackets", url: "http://[::1]/path", host: "[::1]"},
+		{name: "simple ipv6 in brackets", url: "http://[::]/path", host: "[::]"},
+		{name: "simple ipv6 in brackets", url: "http://[2001:db8::]/path", host: "[2001:db8::]"},
+		{name: "simple ipv6 in brackets", url: "http://[::1234:5678]/path", host: "[::1234:5678]"},
+		{name: "simple ipv6 in brackets", url: "http://[2001:db8::1234:5678]/path", host: "[2001:db8::1234:5678]"},
+		{name: "full ipv6 in brackets", url: "http://[2001:db8:3333:4444:5555:6666:7777:8888]/path", host: "[2001:db8:3333:4444:5555:6666:7777:8888]"},
 		{name: "ipv6 with port", url: "http://[::1]:8080/path", host: "[::1]"},
+		{name: "ipv6 with port", url: "http://[::1234:5678]:8080/path", host: "[::1234:5678]"},
+		{name: "ipv6 with port", url: "http://[2001:db8::1234:5678]:8080/path", host: "[2001:db8::1234:5678]"},
+		{name: "ipv6 with port", url: "http://[2001:db8:3333:4444:5555:6666:7777:8888]:8080/path", host: "[2001:db8:3333:4444:5555:6666:7777:8888]"},
 		{name: "simple with port", url: "http://host:8080/path", host: "host"},
 		{name: "fqdn with port", url: "http://sub.host.com:8080/path", host: "sub.host.com"},
 		{name: "idna simple", url: "http://aaa😀😀😀:8080/path", host: "xn--aaa-th33baa"},