The format of the alt
parameter is strictly defined by [RFC 7838][] as an
ASCII string containing a comma-delimited list of “alternative” protocols
associated with a specific host and port.
For example, the value 'h2="example.org:81"'
indicates that the HTTP/2
protocol is available on the host 'example.org'
on TCP/IP port 81. The
host and port must be contained within the quote ("
) characters.
Multiple alternatives may be specified, for instance: 'h2="example.org:81",
h2=":82"'
.
The protocol identifier ('h2'
in the examples) may be any valid
[ALPN Protocol ID][].
The syntax of these values is not validated by the Node.js implementation and are passed through as provided by the user or received from the peer.