Sending a json document using a supplied certificate - json

Question

I have been supplied a certificate that is required to send a json claim to an uri that has an api for sending the claim. The line in error is: handler.ClientCertificates.Add(certificate)
The following is my code:
Public Shared Sub Main()
Dim path As String = "E:\DRDRW_Update\Web Based Billing\vendorsupplied.pfx"
Dim password As String = "Password"
Dim strGateway As String = "https://MCE/api/WebServiceClaim"
Dim collection = New X509Certificate2Collection()
collection.Import(path, password, X509KeyStorageFlags.Exportable)
Dim certificate = collection(0)
Dim PathClaim As String = "E:\Sample Claim Submission JSON.txt"
Dim fi As New IO.FileInfo(PathClaim)
Dim jsonclaim As String = IO.File.ReadAllText(fi.FullName)
System.Net.ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12
Dim handler As New WebRequestHandler()
handler.ClientCertificates.Add(certificate)
' custom certificate validation handler to ignore untrusted remote certificate
ServicePointManager.ServerCertificateValidationCallback = New RemoteCertificateValidationCallback(AddressOf ValidateServerCertificate)
Using client = New HttpClient(handler)
Dim serializedProduct = JsonConvert.SerializeObject(jsonclaim)
Dim content = New StringContent(serializedProduct, Encoding.UTF8, "application/json")
content.Headers.Add("header1", "header2") ' require header
content.Headers.Add("token", "xxxxxxx-yyyy-zzzz")
Dim result = client.PostAsync(strGateway, content).Result ' ensures task is synchronous
' deserialize the saveresultmodel from the WS response and check for claim validation errors
Dim success As Boolean = False
If result.IsSuccessStatusCode Then
Dim resultResult As String = result.Content.ReadAsStringAsync().Result
Dim claimResult = JsonConvert.DeserializeObject(resultResult)
If claimResult.Errors.Count = 0 Then
success = True
Else
' output error results to console
For Each [error] In claimResult.Errors
Console.WriteLine(JsonConvert.SerializeObject([error]))
Next [error]
End If
End If
End Using
End Sub
Public Class WebRequestHandler
Inherits HttpClientHandler
End Class

Answer 1

The issue is that you have declared your own class for the WebRequestHandler. This is not the same as the System.Net.Http.WebRequestHandler.
Visual Studio had a "nice" feature offering to do this for you when it discovers a missing reference with something like "Generate Class for WebRequestHandler." This usually happens when you copy/paste code from another source and the reference was not fully defined. I never take this option and find it a weird way to approach writing code.
You do need to change your code to reference the correct handler like so.
Dim handler As New System.Net.Http.WebRequestHandler
The reason you are getting an error with that is that your project now needs a reference to another assembly (dll) with that class in it. To figure this out, I used google to find the documentation page here and noted this text: Assembly:
System.Net.Http.WebRequest (in System.Net.Http.WebRequest.dll).
This tells us to add the System.Net.Http.WebRequest reference to the project in order to access this class.

Answer 2

I had two issues, the first was answered by #GMan80013 by putting a reference to System.Net.Http.WebRequest.dll. The other was caused by the use of self-signing certificates. The ServicePointManager.ServerCertificateValidationCallback function needs to return true to ignore the issue of certificate validation caused by self-signed certificates.