crypto/tls: be more specific about errors bad record MAC

[OO00O0O]

I've got error tls: bad record MAC
Problem was that service was making request over https://127.0.0.1, rather http://127.0.0.1.
Proposal would be, to provide more specific error message that could be used resolving incidents.
Example: bad record MAC - request without domain

[seankhliao]

cc @FiloSottile

[galdor]

I get these errors each time Curl (and probably other clients) connects to an HTTP server with TLS. The server is using a valid certificate but Curl does not have the right CA certificate, so it fails as expected ("curl: (60) SSL certificate problem: unable to get local issuer certificate"). However Go's net/http server logs:

http: TLS handshake error from <address>: local error: tls: bad record MAC

This message is not logged if Curl uses the right CA. Should the TLS layer log these kinds of message? They seem to be completely unrelated to the server and pollute logs.