@zentrick/alpn-agent
v0.1.2
Published
Negotiates ALPN and handles transparent https and h2 connections
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alpn-agent
A helper library to deal with ALPN negotiation of TLS connections.
Exposes an ALPNAgent
class which inherits from https.Agent
but extends it
with the following:
ALPNAgent#negotiateALPN(options)
which connects to the specified host and negotiates the ALPN protocol, returning aPromise
to the negotiated protocol as a string.ALPNAgent#createH1Session(options)
which connects to the specified host and negotiates anhttp/1.1
TLS socket. Returns aPromise
to a Nodetls.TLSSocket
.ALPNAgent#createH2Session(options)
which connects to the specified host and negotiates anh2
session. Returns aPromise
to a Nodehttp2.ClientHttp2Session
.
Use as a standard Agent
Because ALPNAgent
inherits from https.Agent
you can use it as a drop-in
replacement in any existing https
request, without having to use the h2
capabilities.
Use in "mixed mode"
To use the library to its full potential, you'd follow the following pattern when performing an HTTP request:
if (options.protocol === 'https') {
const alpnProto = await alpnAgent.negotiateALPN(options)
if (alpnProto === 'h2') {
const session = await alpnAgent.createH2Session(options)
// perform standard h2 request against this `ClientHttp2Session`
} else {
// perform standard https request with `agent` option set to the `ALPNAgent`
// instance
}
} else {
// perform standard http request with `agent` option set to a standard
// `http.Agent` instance
}
Optimizations
- Calling
negotiateALPN
might establish a new socket to the remote host, this socket will be remembered in a cache for future use when you perform a request against this remote host. - Calling
negotiateALPN
will return without establishing a new connection, if an existing negotiated connection is already available to provide the answer. - The
ALPNAgent
will maintain a TLS session cache for you which will enable fast session resumption on subsequent connections. - By default, the Nagle algorithm will be disabled on all sockets by calling
socket.setNoDelay(true)
. - You can provide an optional
lookup
function through theALPNAgent
constructor options if you'd like to redirect DNS lookups to your own function. This can be useful if you'd like to cache DNS responses locally.