.NET Core Custom Server Certificate CA

Question

I want to make a call to Kubernetes API from .NET Core app outside the cluster.

I have an HttpClient with an HttpClientHandler where I set this callback to ignore invalid (untrusted) certificates and it works:

handler.ServerCertificateCustomValidationCallback +=
    (message, certificate, chain, errors) => true;

But in my kubeconfig from kubectl I have this:

...
clusters:
- cluster:
    certificate-authority-data: SOME_AUTHORITY_DATA
    server: https://myserver.io:443
...

How can I validate server certificate using that certificate-authority-data in my application?

bartonjs bartonjs · Accepted Answer · 2018-06-12T14:30:19

private static byte[] s_issuingCABytes = { ... };

handler.ServerCertificateCustomValidationCallback +=
    (message, certificate, chain, errors) =>
    {
        const SslPolicyErrors Mask =
#if CA_IS_TRUSTED
            ~SslPolicyErrors.None;
#else
            ~SslPolicyErrors.RemoteCertificateChainErrors;
#endif

        // If a cert is not present, or it didn't match the host.
        // (And if the CA should have been root trusted anyways, also checks that)
        if ((errors & Mask) != SslPolicyErrors.None)
        {
            return false;
        }

        foreach (X509ChainElement element in chain.ChainElements)
        {
            if (element.Certificate.RawData.SequenceEqual(s_issuingCABytes))
            {
                // The expected certificate was found, huzzah!
                return true;
            }
        }

        // The expected cert was not in the chain.
        return false;
    };

.NET Core Custom Server Certificate CA

1 Answers