Webhook Documentation


using System;
using System.Security.Cryptography;
using System.Text;
using System.Threading.Tasks;

// The below function will process the incoming WebHook request and return HttpStatusCode'OK' if it is successful
public static async Task<HttpResponseMessage> CompareHMAC(HttpRequestMessage req)
{
    try
    {
        // Get request data from the message body
        string requestData = await req.Content.ReadAsStringAsync().Trim();
        if (string.IsNullOrEmpty(requestData))
        {
            // Return bad request if the request body is empty
            return req.CreateResponse(HttpStatusCode.BadRequest, "Please pass a name on the query string or in the request body");
        }

        // Get the ModusLink HMAC values from request Header
        if (!req.Headers.TryGetValues("X-Moduslink-HMAC-SHA256", out IEnumerable<string> headerValues))
        {
            // Return bad request if the header is missing
            return req.CreateResponse(HttpStatusCode.BadRequest, "Please provide the X-Moduslink-HMAC-SHA256 header");
        }
        string HMAHeader = headerValues.FirstOrDefault().Trim();

        // Assign the SecretKey value (Please replace it with original secret key)
        string secretKey = "a2196c7d-78ad-4e8b-98db-d79a16e13f75";

       // Calculate the HMAC values using the secretkey and requestData
       using (HMACSHA256 hmac = new HMACSHA256(Encoding.UTF8.GetBytes(secretKey)))
        {
            byte[] hash = hmac.ComputeHash(Encoding.UTF8.GetBytes(requestData));
            string calculatedHMAC = Convert.ToBase64String(hash);

            // Verify whether the computed HMAC value and the HMAC value in the request Header are matching
            if (HMAHeader == calculatedHMAC)
            {
                // The values are matching
                return req.CreateResponse(HttpStatusCode.OK, "WebhookInfo processed successfully");
            }
            else
            {
                return req.CreateResponse(HttpStatusCode.OK, "WebhookInfo not processed due to the mismatch in XModuslinkHMACSHA256 value");
            }
        }
    }
    catch (Exception ex)
    {
        return req.CreateResponse(ex);
    }
}

           

package org.example.functions;

import java.util.*;
import com.microsoft.azure.functions.annotation.*;
import com.microsoft.azure.functions.*;
import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;
import javax.naming.Context;

public class CompareHMACValue
{
    @@FunctionName("CompareHMACValue")
    public HttpResponseMessage run(
    @@HttpTrigger(name = "req", methods = {HttpMethod.GET, HttpMethod.POST}, authLevel = AuthorizationLevel.ANONYMOUS) HttpRequestMessage> request,
    final ExecutionContext context)
    {
        // Parse query parameter
        String query = request.getQueryParameters().get("name");
        String requestData = request.getBody().orElse(query);
        context.getLogger().info( "Message: " + requestData);

        //Get the SecretKey value
        //String secretKey = System.getenv("secretkey");
        //String secretKey =  request.getHeaders().get("secretkey");
        String secretKey = request.getHeaders().containsKey("secretkey") ? request.getHeaders().get("secretkey") : System.getenv("secretkey");
        if (secretKey == null || secretKey == "") {
            secretKey = "a2196c7d-78ad-4e8b-98db-d79a16e13f75";
        }
        context.getLogger().info( "secretKey: " + secretKey);

        //Get the  ModusLink HMAC values from request Header
        String hmacHeader = request.getHeaders().get("x-moduslink-hmac-sha256");
        context.getLogger().info( "HMAC Header: " + hmacHeader);
        try
        {
            boolean verified = VarifyHMACValue(hmacHeader, secretKey, requestData,context);
            if (verified )
            {
                return request.createResponseBuilder(HttpStatus.OK).body("The calculated HMAC value is matching with the 'X-Moduslink-HMAC-SHA256' value in the header section, Calculated HMAC Value:  " ).build();
            }
            else
            {
                return request.createResponseBuilder(HttpStatus.BAD_REQUEST).body("The calculated HMAC value is not  matching with the 'X-Moduslink-HMAC-SHA256' value  in the header section, Calculated HMAC value:  ").build();
            }

            }
            catch(Exception Ex)
            {
                return request.createResponseBuilder(HttpStatus.BAD_REQUEST).body("WebhookInfo not processed due to Exception " + Ex).build();
            }
        }
        public static Boolean VarifyHMACValue(String hmacHeader, String secretKey , String data, ExecutionContext context)
        {
            try
            {
                SecretKeySpec secretKeySpec = new SecretKeySpec(secretKey.getBytes("UTF-8"), "HmacSHA256");
                Mac mac = Mac.getInstance("HmacSHA256");
                mac.init(secretKeySpec);
                byte[] hmac  = mac.doFinal(data.getBytes("UTF-8"));
                String calculatedHMAC = Base64.getEncoder().encodeToString(hmac);
                context.getLogger().info( "calculated HMAC: " + calculatedHMAC);
                return  hmacHeader.equals(calculatedHMAC) ;
            }
            catch (Exception Ex)
            {
                return  false;
            }
        }
}