Band-aid for net.Conn implementations that don't support deadlines.
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Deaconn stands for "deadline connection". For usage, see below... |
If an http.Server's underlying net.Conns do not support deadline methods, WebSockets and any other feature which relies on "hijacking" connections will not work.
This is a small project that was born out of need... I needed to support HTTP traffic over a net.Conn implementation which did not support the SetDeadline, SetReadDeadline, and SetWriteDeadline methods.
This is a problem because the net/http package relies on the deadline methods of net.Conn to support certain features.
Specifically, the net/http package uses SetReadDeadline() to set a connection's deadline to a time in the past in order to abort pending/blocked Read()s on it.
An example where this is done is when type-asserting an http.ResponseWriter as an http.Hijacker and then invoking Hijack() on it (as is done to handle a WebSocket upgrade for instance).
The net.Conn implementation that I specifically was using (which lacked deadlines support) was an (golang.org/x/crypto/ssh).Channel.
More Details:
- There's an open GitHub issue in the Golang GitHub repo (#65930) that tracks the lack of deadline methods support in the
ssh.Channel - There's an open GitHub issue in the Golang GitHub repo (#67152) that tracks the specific issue I faced (i.e.
Hijack()hanging for WebSocket upgrades when HTTP is served over anssh.Channel) - There's a an open Gerrit patch set in the Golang Gerrit repo that I have personally tested to solve my specific use case effectively
To wrap a net.Listener in a listener that adds deadlines support to net.Conns:
wrappedListener := deaconn.NewListenerWithDeadlines(listener)
defer wrappedListener()
// use the wrappedListener as you would use your original listener
To wrap a single net.Conn to add deadline support to it:
wrappedConn := deaconn.NewConnWithDeadlines(conn)
// use the wrappedConn as you would use your original conn