If cert verification fails, this will be called to let the user make the final decision of whether to allow the connection to proceed. Returns 0 to allow the connection or a negative value to indicate an error.
This will be called if the remote host requires authentication in order to connect to it.
Payload to be provided to the credentials and certificate check callbacks.
The type of proxy to use, by URL, auto-detect.
The URL of the proxy.
Options for connecting through a proxy
Note that not all types may be supported, depending on the platform and compilation options.