Webhook - URL Validation failed!

API and Webhooks
1

Hey I want a help to solve why I’m getting the error: URL Validation Failed!, always

I’m following up the example posted here: https://developers.zoom.us/docs/api/rest/webhook-reference/#validate-your-webhook-endpoint, just in my case is from C#, using Azure function to validate the URL
I have configured ngrok to validate my endpoint but I’m not sure what happens really


[FunctionName("Events")]
        public static async Task<IActionResult> Run(
            [HttpTrigger(AuthorizationLevel.User, "post", Route = "Zoom")] HttpRequest req,
            ILogger log)
        {
            var eventSecretToken = "Here my secret token goes";
            log.LogInformation("C# HTTP trigger function processed a request.");
            string requestBody = await new StreamReader(req.Body).ReadToEndAsync();
            var data = JsonConvert.DeserializeObject<DataResponse>(requestBody);
            var sha256 = new System.Security.Cryptography.HMACSHA256();
            sha256.Key = Encoding.ASCII.GetBytes(eventSecretToken);
            var hash = sha256.ComputeHash(System.Text.Encoding.ASCII.GetBytes(data.PayLoad.PlainToken));
            var hashString = ToHex(hash, false);

            return new OkObjectResult(new
            {
                plainToken = data.PayLoad.PlainToken,
                encryptedToken = hash,

            });

        }

        private static string ToHex(byte[] bytes, bool upperCase)
        {
            StringBuilder result = new StringBuilder(bytes.Length * 2);
            for (int i = 0; i < bytes.Length; i++)
                result.Append(bytes[i].ToString(upperCase ? "X2" : "x2"));
            return result.ToString();
        }
2

Hi @vladimir.rivera
Thanks for reaching out to us!
Have you taken a look at this sample app?

It looks like in your function you are not listening to the endpoint.url_validation event

3

Hi Elisa,

I convert that code into C# code and I have the same problem.

if (!(payload.Event.IsNullOrDefault()) && payload.Event == “endpoint.url_validation”)
{

            var hashForValidate = new System.Security.Cryptography.HMACSHA256(Encoding.UTF8.GetBytes(secretToken)).ComputeHash(Encoding.UTF8.GetBytes(payload.payload.plainToken));

             //hmac.ComputeHash(Encoding.UTF8.GetBytes(payload.payload.plainToken));
            var hashed = ToHex(hashForValidate, false);
            var validationResponse = new
            {
                message = new
                {
                    plainToken = payload.payload.plainToken,
                    encryptedToken = hashed
                },
                status = 200
            };

            log.LogInformation($"Validation Response: {JsonConvert.SerializeObject(validationResponse)}");

            return new OkObjectResult(validationResponse);
        }
4

Any update on the above request?

5

Hi All, this way I fix the problem:

[FunctionName(“Events”)]
public static async Task Run(
[HttpTrigger(AuthorizationLevel.User, “post”)] HttpRequest req,
ILogger log)
{
log.LogInformation(“C# Zoom Webhook function processed a request.”);

        string hashed = "";
        string requestBody = await new StreamReader(req.Body).ReadToEndAsync();
        var data = JsonConvert.DeserializeObject<ZoomWebhookPayload>(requestBody);

        //To validate EndPoint in Zoom MarketPlace
        if (!(string.IsNullOrEmpty(data.Event)) && data.Event == "endpoint.url_validation")
        {
            var encoding = new System.Text.ASCIIEncoding();
            var sha256 = new System.Security.Cryptography.HMACSHA256();
            sha256.Key = encoding.GetBytes(Environment.GetEnvironmentVariable("ZOOM_WEBHOOK_SECRET_TOKEN"));
            var hash = sha256.ComputeHash(encoding.GetBytes(data.payload.plainToken));
            hashed = ToHex(hash, false);
            return new OkObjectResult(new
            {
                plainToken = data.payload.plainToken,
                encryptedToken = hashed
            });
        }

}
private static string ToHex(byte bytes, bool upperCase)
{
StringBuilder result = new StringBuilder(bytes.Length * 2);
for (int i = 0; i < bytes.Length; i++)
result.Append(bytes[i].ToString(upperCase ? “X2” : “x2”));
return result.ToString();
}
protected class ZoomWebhookPayload
{
public ZoomWebhookEventPayload payload { get; set; }
public string Event { get; set; }
}

    protected class ZoomWebhookEventPayload
    {
        public string plainToken { get; set; }

    }
6

hello @vladimir.rivera
i did the same api like
public async Task ZoomEndSessionWebhook()
{
string requestBody = await new StreamReader(_baseService.HttpContextAccessor.HttpContext.Request.Body).ReadToEndAsync();
var timeSpane = _baseService.HttpContextAccessor.HttpContext.Request.Headers[“x-zm-request-timestamp”].ToString();
var EndZoomSessionWebhookDto = JsonConvert.DeserializeObject(requestBody);
var encoding = new System.Text.ASCIIEncoding();
var sha256 = new System.Security.Cryptography.HMACSHA256();
string message = $“v0:{timeSpane}:{requestBody}”;
sha256.Key = encoding.GetBytes(_zoomSetting.ZoomWebhookSecretKey);
var hash = sha256.ComputeHash(encoding.GetBytes(message));

   var hashed = ToHex(hash, false);
   
   string signature = $"v0={hashed}";
  
   if (signature == _baseService.HttpContextAccessor.HttpContext.Request.Headers["x-zm-signature"]) {
     if (EndZoomSessionWebhookDto.@event == "endpoint.url_validation") { 
         var plain = new System.Security.Cryptography.HMACSHA256();
     plain.Key = encoding.GetBytes(_zoomSetting.ZoomWebhookSecretKey);
     var hashForValidate = plain.ComputeHash(encoding.GetBytes(EndZoomSessionWebhookDto.payload.plainToken));

var hashString = ToHex(hashForValidate, false);
return Ok(new { plainToken = result.message.plainToken, encryptedToken = result.message.encryptedToken });
but still getting invalid url

7

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