This continues to asserts the known version while decoding. The client
will only ever generate the latest version while encoding and if the
response needs to change, the impetus will be a new feature, set in the
deserialized request, which can be used as a distinguisher.
Malicious clients and proxies can provide potentially malicious strings
in the polls. This validates the NAT type and proxy type strings to
ensure that malformed strings are not displayed on a web page
or passed to any of our monitoring infrastructure.
If a client or proxy supplies an invalid NAT type, we return an error
message. If a proxy supplies an unknown proxy type, we set the proxy
type to unknown.
Send the client poll request and response in a json-encoded format in
the HTTP request body rather than sending the data in HTTP headers. This
will pave the way for using domain-fronting alternatives for the
Snowflake rendezvous.
