add cors support

main.go

@@ -35,9 +35,9 @@ func (t *TbAccountInfo) TableName() string {
 	return "tb_account_info"
 }
 
-// RPC请求结构体
-// 这里只处理eth_getBalance的params
-// 其他方法直接转发
+// RPC request structure
+// Only handle params for eth_getBalance here
+// Forward other methods directly
 
 type RPCRequest struct {
 	Jsonrpc string        `json:"jsonrpc"`
@@ -55,36 +55,45 @@ type RPCResponse struct {
 
 var (
 	db         *sql.DB
-	rpcBackend = os.Getenv("ETH_RPC_BACKEND") // 真实以太坊RPC地址，建议用环境变量配置
+	rpcBackend = os.Getenv("ETH_RPC_BACKEND") // Real Ethereum RPC address, recommend using environment variable
 )
 
 func main() {
-	// 初始化数据库连接
+	// Initialize database connection
 	var err error
-	dsn := os.Getenv("MYSQL_DSN") // 例如 "user:password@tcp(127.0.0.1:3306)/dbname"
+	dsn := os.Getenv("MYSQL_DSN") // Example: "user:password@tcp(127.0.0.1:3306)/dbname"
 	db, err = sql.Open("mysql", dsn)
 	if err != nil {
-		log.Fatalf("数据库连接失败: %v", err)
+		log.Fatalf("Database connection failed: %v", err)
 	}
 	defer db.Close()
 
 	http.HandleFunc("/", proxyHandler)
-	log.Println("RPC代理服务启动，监听端口: 8545")
+	log.Println("RPC proxy service started, listening on port: 8545")
 	log.Fatal(http.ListenAndServe(":8545", nil))
 }
 
 func proxyHandler(w http.ResponseWriter, r *http.Request) {
+	// Add CORS support
+	setCORSHeaders(w, r)
+
+	// Handle preflight requests
+	if r.Method == "OPTIONS" {
+		w.WriteHeader(http.StatusOK)
+		return
+	}
+
 	body, err := ioutil.ReadAll(r.Body)
 	if err != nil {
-		http.Error(w, "读取请求失败", http.StatusBadRequest)
+		http.Error(w, "Failed to read request", http.StatusBadRequest)
 		return
 	}
 	defer r.Body.Close()
 
 	var reqs []RPCRequest
-	// 先尝试解析为批量请求
+	// Try to parse as batch request first
 	if err := json.Unmarshal(body, &reqs); err == nil {
-		// 处理批量请求
+		// Handle batch request
 		if len(reqs) > 1 {
 			req := reqs[0]
 			resp := RPCResponse{
@@ -128,10 +137,24 @@ func proxyHandler(w http.ResponseWriter, r *http.Request) {
 			return
 		}
 	}
-	// 其他情况直接转发
+	// Forward other cases directly
 	forwardToBackend(w, body)
 }
 
+func setCORSHeaders(w http.ResponseWriter, r *http.Request) {
+	origin := r.Header.Get("Origin")
+	if origin != "" {
+		w.Header().Set("Access-Control-Allow-Origin", origin)
+	} else {
+		w.Header().Set("Access-Control-Allow-Origin", "*")
+	}
+
+	w.Header().Set("Access-Control-Allow-Methods", "POST, GET, OPTIONS, PUT, DELETE")
+	w.Header().Set("Access-Control-Allow-Headers", "Accept, Content-Type, Content-Length, Accept-Encoding, X-CSRF-Token, Authorization, X-Real-IP, X-Forwarded-For")
+	w.Header().Set("Access-Control-Allow-Credentials", "true")
+	w.Header().Set("Access-Control-Max-Age", "86400")
+}
+
 func accountExists(address string) bool {
 	var count int
 	query := "SELECT COUNT(1) FROM tb_account_info WHERE account_address = ? AND is_deleted = 0"
@@ -140,7 +163,7 @@ func accountExists(address string) bool {
 		if err == sql.ErrNoRows {
 			return false
 		} else {
-			log.Printf("数据库查询错误: %v", err)
+			log.Printf("Database query error: %v", err)
 		}
 		return true
 	}
@@ -150,10 +173,18 @@ func accountExists(address string) bool {
 func forwardToBackend(w http.ResponseWriter, body []byte) {
 	resp, err := http.Post(rpcBackend, "application/json", bytes.NewReader(body))
 	if err != nil {
-		http.Error(w, "后端RPC请求失败", http.StatusBadGateway)
+		http.Error(w, "Backend RPC request failed", http.StatusBadGateway)
 		return
 	}
 	defer resp.Body.Close()
-	w.Header().Set("Content-Type", "application/json")
+
+	// Copy response headers, including possible CORS headers
+	for key, values := range resp.Header {
+		for _, value := range values {
+			w.Header().Add(key, value)
+		}
+	}
+
+	w.WriteHeader(resp.StatusCode)
 	io.Copy(w, resp.Body)
 }