Impl WebSocketClient redirect

http/client/WebSocketClient.cpp

@@ -38,7 +38,9 @@ int WebSocketClient::open(const char* _url, const http_headers& headers) {
         }
     }
     hlogi("%s", url.c_str());
-    http_req_.reset(new HttpRequest);
+    if (!http_req_) {
+        http_req_.reset(new HttpRequest);
+    }
     // ws => http
     http_req_->url = "http" + url.substr(2, -1);
     http_req_->ParseUrl();
@@ -107,7 +109,22 @@ int WebSocketClient::open(const char* _url, const http_headers& headers) {
             size -= nparse;
             if (http_parser_->IsComplete()) {
                 if (http_resp_->status_code != HTTP_STATUS_SWITCHING_PROTOCOLS) {
-                    hloge("server side not support websocket!");
+                    // printf("websocket response:\n%s\n", http_resp_->Dump(true, true).c_str());
+                    if (http_req_->redirect && HTTP_STATUS_IS_REDIRECT(http_resp_->status_code)) {
+                        std::string location = http_resp_->headers["Location"];
+                        if (!location.empty()) {
+                            hlogi("redirect %s => %s", http_req_->url.c_str(), location.c_str());
+                            std::string ws_url = location;
+                            if (hv::startswith(location, "http")) {
+                                ws_url = hv::replace(location, "http", "ws");
+                            }
+                            // NOTE: not triggle onclose when redirecting.
+                            channel->onclose = NULL;
+                            open(ws_url.c_str());
+                            return;
+                        }
+                    }
+                    hloge("server side could not upgrade to websocket: status_code=%d", http_resp_->status_code);
                     channel->close();
                     return;
                 }