connect to a server with a self-signed certificate - asp.net-web-api

Question

Ive been doing some research about how to consume a web api executed on my localhost throught a xamarin app. The web api works perfect, I can adding and getting the data to/from my sql server using a web browser but if I try to connect xamarin to it Ive always received authentication error (Mono.Btls.MonoBtlsException: Ssl error:1000007d:SSL routines:OPENSSL_internal:CERTIFICATE_VERIFY_FAILED). Im basically doind this. I followed this post:
http://xamarininterviewquestion.blogspot.com/2019/06/ssl-certificate-and-public-key-pinning.html
So as it definitly didnt work, Id like to try another way;
Set TLSConfig DangerousAcceptAnyServerCertificateValidator to true. Because for know Im happy if Im able to test it.
Thats cool but as Im not a pro I have no idea about implement this;
var httpHandler = new HttpClientHandler();
// Return `true` to allow certificates that are untrusted/invalid
httpHandler.ServerCertificateCustomValidationCallback =
HttpClientHandler.DangerousAcceptAnyServerCertificateValidator;
Ive got "DangerousAcceptAnyServerCertificateValidator" doesnt have a definition.
Thank you all in advance and sorry if Ive not been clear.

Answer 1

DangerousAcceptAnyServerCertificateValidator isn't applicable to Xamarin platforms, according to its documentation.
But literally you can write the same code like,
var handler = new HttpClientHandler();
handler.ServerCertificateCustomValidationCallback += (sender, cert, chain, sslPolicyErrors) => true;
HttpClient client = new HttpClient(handler);
https://stackoverflow.com/a/64741829/11182

Answer 2

if you are using Refit then you can do this
public HttpClient PreparedClient()
{
HttpClientHandler handler = new HttpClientHandler();
handler.ServerCertificateCustomValidationCallback += (sender, cert, chain, sslPolicyErrors) => { return true; };
HttpClient client = new HttpClient(handler) { BaseAddress = new Uri(EndpointConstants.BaseUrl) };
return client;
}
private T RefitApi<T>() => RestService.For<T>(PreparedClient());
and if you need to specify settings you can do this
private T RefitApiWithToken<T>() => RestService.For<T>(PreparedClient(), refitSettings);

Answer 3

When using Refit for Xamarin forms
public HttpClient PreparedClient()
{
HttpClientHandler handler = new HttpClientHandler();
handler.ServerCertificateCustomValidationCallback += (sender, cert, chain, sslPolicyErrors) => { return true; };
HttpClient client = new HttpClient(handler) { BaseAddress = new Uri(EndpointConstants.BaseUrl) };
return client;
}
var apiResponse = RestService.For<T>(PreparedClient());