From b46d3b802f9620ee43c2f6d173a54f74af9d2362 Mon Sep 17 00:00:00 2001
From: dingjun <fangdingjun@gmail.com>
Date: Mon, 19 Apr 2021 13:40:33 +0800
Subject: [PATCH] add retry logical

---
 handler.go | 33 ++++++++++++++++++++++-----------
 1 file changed, 22 insertions(+), 11 deletions(-)

diff --git a/handler.go b/handler.go
index 58ab149..63d3529 100644
--- a/handler.go
+++ b/handler.go
@@ -49,6 +49,9 @@ func handleHTTP(w http.ResponseWriter, r *http.Request) {
 	tr := &http.Transport{
 		DialContext: localDialer,
 	}
+
+	log.Debugf("%s %s", r.Method, r.RequestURI)
+
 	resp, err := tr.RoundTrip(r)
 	if err != nil {
 		log.Errorln(err)
@@ -70,22 +73,30 @@ func handleHTTP(w http.ResponseWriter, r *http.Request) {
 	io.Copy(w, resp.Body)
 }
 
-func handleConnect(w http.ResponseWriter, r *http.Request) {
-	ip := getLocalIP()
+func mydail(uri string) (net.Conn, error) {
+	addr := &net.TCPAddr{}
+	dialer := &net.Dialer{
+		LocalAddr: addr,
+		Timeout:   3 * time.Second,
+	}
 
-	log.Debugf("connect to %s, use local ip %s", r.RequestURI, ip)
+	for i := 0; i < 3; i++ {
+		ip := getLocalIP()
+		addr.IP = net.ParseIP(ip)
 
-	addr := &net.TCPAddr{
-		IP:   net.ParseIP(ip),
-		Port: 0,
-	}
+		log.Debugf("connect to %s, use local ip %s", uri, ip)
 
-	dialer := &net.Dialer{
-		LocalAddr: addr,
-		Timeout:   10 * time.Second,
+		conn, err := dialer.Dial("tcp", uri)
+		if err == nil {
+			return conn, err
+		}
+		log.Errorf("connect to %s, %s, retrying", uri, err)
 	}
+	return nil, fmt.Errorf("connect to %s, max retries reached, give up", uri)
+}
 
-	conn, err := dialer.Dial("tcp", r.RequestURI)
+func handleConnect(w http.ResponseWriter, r *http.Request) {
+	conn, err := mydail(r.RequestURI)
 	if err != nil {
 		log.Errorln(err)
 		http.Error(w, "connection failed", http.StatusBadGateway)