Unsupported algorithm on RTCDtlsTransport.start

[lgrahl]

In the RTCDtlsTransport.start method, the implementation should check whether the fingerprint algorithm is supported and raise an appropriate exception.

For example, implementations may decide to not support SHA-1 but that does not make the DTLS parameters invalid. So, I don't think InvalidParameters is what we want to raise. My proposal would be NotSupportedError as it is also used in RTCCertificate.generateCertificate and in the Web Cryptography API for that purpose.

Related tweet from @ibc: https://twitter.com/ibc_tw/status/902121596613271552

[lgrahl]

Having said this, IIRC there can be multiple fingerprints. So, if all of the provided fingerprints have been created by an unsupported algorithm, NotSupportedError should be raised.

[ibc]

The issue is much worse in Edge. If you call setRemoteParameters by passing sha-1 (not supported in Edge) , sha-224 (not supported in Edge) and the others sha-256, sha-384 and sha-512 (all of them supported in Edge), Edge raises InvalidParameters, so it seems that it just takes the first algorithm.

[lgrahl]

But that's Edge-specific then.