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November 14, 2023 19:17
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The solution to getting Paypal's verify endpoint to work was to serialize JSON manually like so:
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| using System; | |
| using System.IO; | |
| using System.Net; | |
| using System.Net.Http; | |
| using System.Net.Http.Headers; | |
| using System.Text; | |
| using System.Threading.Tasks; | |
| using Microsoft.AspNetCore.Authorization; | |
| using Microsoft.AspNetCore.Http; | |
| using Microsoft.AspNetCore.Mvc; | |
| using Newtonsoft.Json; | |
| namespace server.Payment | |
| { | |
| public class PaymentController : Controller | |
| { | |
| private static readonly HttpClient client = new HttpClient(); | |
| [HttpPost("api/checkout/webhook")] | |
| [AllowAnonymous] | |
| public async Task<IActionResult> HandleWebhook() | |
| { | |
| var json = await new StreamReader(HttpContext.Request.Body).ReadToEndAsync(); | |
| var headers = HttpContext.Request.Headers; | |
| await VerifyEvent(json, headers); | |
| // handle etc... | |
| return Ok(); | |
| } | |
| private async Task VerifyEvent(string json, IHeaderDictionary headerDictionary) | |
| { | |
| var bearerToken = await Authenticate(); | |
| client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", bearerToken); | |
| // !!IMPORTANT!! | |
| // Without this direct JSON serialization, PayPal WILL ALWAYS return verification_status = "FAILURE". | |
| // This is probably because the order of the fields are different and PayPal does not sort them. | |
| var paypalVerifyRequestJsonString = $@"{{ | |
| ""transmission_id"": ""{headerDictionary["PAYPAL-TRANSMISSION-ID"][0]}"", | |
| ""transmission_time"": ""{headerDictionary["PAYPAL-TRANSMISSION-TIME"][0]}"", | |
| ""cert_url"": ""{headerDictionary["PAYPAL-CERT-URL"][0]}"", | |
| ""auth_algo"": ""{headerDictionary["PAYPAL-AUTH-ALGO"][0]}"", | |
| ""transmission_sig"": ""{headerDictionary["PAYPAL-TRANSMISSION-SIG"][0]}"", | |
| ""webhook_id"": ""<get from paypal developer dashboard>"", | |
| ""webhook_event"": {json} | |
| }}"; | |
| var content = new StringContent(paypalVerifyRequestJsonString, Encoding.UTF8, "application/json"); | |
| var resultResponse = await client.PostAsync("https://api-m.sandbox.paypal.com/v1/notifications/verify-webhook-signature", content); | |
| var responseBody = await resultResponse.Content.ReadAsStringAsync(); | |
| var verifyWebhookResponse = JsonConvert.DeserializeObject<VerifyWebhookResponse>(responseBody); | |
| if (verifyWebhookResponse.verification_status != "SUCCESS") | |
| { | |
| throw new Exception("failed to verify webhook response"); | |
| } | |
| } | |
| private async Task<string> Authenticate() | |
| { | |
| // TODO: make all hard coded values configurable | |
| var request = WebRequest.Create("https://api-m.sandbox.paypal.com/v1/oauth2/token"); | |
| request.Method = "POST"; | |
| request.ContentType = "application/x-www-form-urlencoded"; | |
| request.Headers.Add("grant_type", "client_credentials"); | |
| var postData = "grant_type=client_credentials"; | |
| var byteArray = Encoding.UTF8.GetBytes(postData); | |
| var dataStream = request.GetRequestStream(); | |
| dataStream.Write(byteArray, 0, byteArray.Length); | |
| dataStream.Close(); | |
| request.ContentType = "application/x-www-form-urlencoded"; | |
| request.ContentLength = byteArray.Length; | |
| var clientId = "<get from paypal developer dashboard>"; | |
| var clientSecret = "<get from paypal developer dashboard>"; | |
| var encoded = Convert.ToBase64String(Encoding.GetEncoding("ISO-8859-1") | |
| .GetBytes(clientId + ":" + clientSecret)); | |
| request.Headers.Add("Authorization", "Basic " + encoded); | |
| try | |
| { | |
| var response = await request.GetResponseAsync(); | |
| using (dataStream = response.GetResponseStream()) | |
| { | |
| var reader = new StreamReader(dataStream); | |
| var responseFromServer = reader.ReadToEnd(); | |
| Console.WriteLine(responseFromServer); | |
| var token = JsonConvert.DeserializeObject<TokenResponse>(responseFromServer); | |
| return token.access_token; | |
| } | |
| } | |
| catch (WebException e) | |
| { | |
| string content; | |
| using (var reader = new StreamReader(e.Response.GetResponseStream())) | |
| { | |
| content = reader.ReadToEnd(); | |
| Console.WriteLine("content", content); | |
| } | |
| throw; | |
| } | |
| } | |
| } | |
| } |
@itfm It must look like this:
{
"verification_status": "SUCCESS"
}
@jsdevtom Thanks for your help bro !!!
@HenryBJ You're very welcome
@jsdevtom Thank you! I wish PayPal's docs were as helpful as your example! I was seeing intermittent failures, which make it even more confusing. This solved it.
@gsmcdonald No problem
Thanks for the detailed explanation. Unfortunately it is not working me! Always giving me FAILURE.
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What does VerifyWebhookResponse look like or where can I find a sample response from PayPal?