easy:SetOpt_AltSvc_Ctrl(bitmask)
bitmask
with the correct get of features to instruct
libcurl how to handle Alt-Svc for the transfers using this handle.
libcurl only accepts Alt-Svc headers over a secure transport, meaning HTTPS. It will also only complete a request to an alternative origin if that origin is properly hosted over HTTPS. These requirements are there to make sure both the source and the destination are legitimate.
Alternative services are only used when setting up new connections. If there exists an existing connection to the host in the connection pool, then that will be preferred.
Setting any bit will enable the alt-svc engine.
#CURLALTSVC_READONLYFILE
#CURLOPT_ALTSVC
even if it gets updated. By default a file specified
with that option will be read and written to as deemed necessary.
#CURLALTSVC_H1
#CURLALTSVC_H2
#CURLALTSVC_H3