Binance API bad request with C# in Fiddler

API Futures API
,
1

I have an outgoing POST (in Spot) from another application, and with the help of Fiddler I want to send another order opening request. I managed to take the necessary data from the original request, sign the request using HMAC256 and send it to Binance, but I get a “bad request” in the response and I don’t understand what’s wrong here. I would appreciate any help.

public static void OnBeforeResponse(Session oSession)
{
    if (oSession.HTTPMethodIs("POST") && oSession.uriContains("order"))
    {
        String strBody = oSession.GetRequestBodyAsString();

        //Price 
        int PriceStart = strBody.IndexOf("price=") + 6;
        int PriceEND = strBody.IndexOf("&", PriceStart);
        string priceStr = strBody.Substring(PriceStart, PriceEND - PriceStart);
        float priceF = float.Parse(priceStr, System.Globalization.CultureInfo.InvariantCulture);

        // SYMBOL
        int symbolStart = strBody.IndexOf("symbol=") + 7;
        int symbolend = strBody.IndexOf("BTC", symbolStart);
        string symbol = strBody.Substring(symbolStart, symbolend - symbolStart);

        // Quantity
        int quantStart = strBody.IndexOf("quantity=") + 9;
        int quantend = strBody.IndexOf("&price", quantStart);
        string quant = strBody.Substring(quantStart, quantend - quantStart);
        float quantity = float.Parse(quant, System.Globalization.CultureInfo.InvariantCulture) * 2;

        // timestamp
        decimal timestamp = Math.Round(Convert.ToDecimal(DateTime.UtcNow.Subtract(new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc)).TotalMilliseconds), 0);

        //Sign
        Encoding ascii = Encoding.ASCII;
        string secretKey = "lfaeGkjitNwvyG2lqDueMhSAOzRFlzL73w5pKRCAvSy7YrxyTkvwKCcHBHj...";
        HMACSHA256 hmac = new HMACSHA256(ascii.GetBytes(secretKey));

        //   string query_string_LIMIT = "symbol="+symbol+"USDT&side=BUY&type=LIMIT&timeInForce=GTC&quantity="+quantity+"&price="+priceF+"&recvWindow=5000&timestamp="+timestamp+"&signature=";

        string result = "symbol=" + symbol + "USDT&side=BUY&type=MARKET&quantity=" + quantity + "&recvWindow=5000&timestamp=" + timestamp + "&signature=";

        String signature = BitConverter.ToString(hmac.ComputeHash(ascii.GetBytes(result))).Replace("-", "");

        oSession.host = "fapi.binance.com";
        string resultRequest = "symbol=" + symbol + "USDT&side=BUY&type=MARKET&quantity=" + quantity + "&recvWindow=5000&timestamp=" + timestamp + "&signature=" + signature;

        byte[] resulByte = System.Text.Encoding.ASCII.GetBytes(resultRequest);

        //oSession.utilReplaceInRequest("api/v3/order","fapi/v1/order?"+resultFin);

        oSession.url = oSession.url.Replace("api/v3/order", "fapi/v1/order?" + resultRequest);

        FiddlerApplication.oProxy.SendRequest(oSession.RequestHeaders, resulByte, null);
    }
}
2

The 400 bad request response comes with a error message in the body. You should use that message to debug the program.

3

i see error - “HTTP/1.1 504 Fiddler - Receive Failure”