@ -1,3 +1,11 @@
// Copyright (c) Tailscale Inc & AUTHORS
// SPDX-License-Identifier: BSD-3-Clause
// Package noiseconn contains an internal-only wrapper around controlbase.Conn
// that properly handles the early payload sent by the server before the HTTP/2
// session begins.
//
// See the documentation on the Conn type for more details.
package noiseconn
import (
@ -16,9 +24,11 @@ import (
)
// Conn is a wrapper around controlbase.Conn.
// It allows attaching an ID to a connection to allow
// cleaning up references in the pool when the connection
// is closed.
//
// It allows attaching an ID to a connection to allow cleaning up references in
// the pool when the connection is closed, properly handles an optional "early
// payload" that's sent prior to beginning the HTTP/2 session, and provides a
// way to return a connection to a pool when the connection is closed.
type Conn struct {
* controlbase . Conn
id int
@ -59,9 +69,13 @@ func (c *Conn) RoundTrip(r *http.Request) (*http.Response, error) {
return c . h2cc . RoundTrip ( r )
}
// getEarlyPayload waits for the early n oise payload to arrive.
// GetEarlyPayload waits for the early N oise payload to arrive.
// It may return (nil, nil) if the server begins HTTP/2 without one.
func ( c * Conn ) getEarlyPayload ( ctx context . Context ) ( * tailcfg . EarlyNoise , error ) {
//
// It is safe to call this multiple times; all callers will block until the
// early Noise payload is ready (if any) and will return the same result for
// the lifetime of the Conn.
func ( c * Conn ) GetEarlyPayload ( ctx context . Context ) ( * tailcfg . EarlyNoise , error ) {
select {
case <- c . earlyPayloadReady :
return c . earlyPayload , c . earlyPayloadErr
@ -71,30 +85,39 @@ func (c *Conn) getEarlyPayload(ctx context.Context) (*tailcfg.EarlyNoise, error)
}
// ReserveNewRequest will reserve a new concurrent request on the connection.
// It returns a non-nil http.RoundTripper if the reservation was successful,
// and any early Noise payload if present. If a reservation was not successful,
// it will return nil with no error.
func ( c * Conn ) ReserveNewRequest ( ctx context . Context ) ( http . RoundTripper , * tailcfg . EarlyNoise , error ) {
earlyPayloadMaybeNil , err := c . getEarlyPayload ( ctx )
//
// It returns whether the reservation was successful, and any early Noise
// payload if present. If a reservation was not successful, it will return
// false and nil for the early payload.
func ( c * Conn ) ReserveNewRequest ( ctx context . Context ) ( bool , * tailcfg . EarlyNoise , error ) {
earlyPayloadMaybeNil , err := c . GetEarlyPayload ( ctx )
if err != nil {
return nil , nil , err
return false , nil , err
}
if c . h2cc . ReserveNewRequest ( ) {
return c , earlyPayloadMaybeNil , nil
return true , earlyPayloadMaybeNil , nil
}
return nil , nil , nil
return false , nil , nil
}
// CanTakeNewRequest reports whether the underlying HTTP/2 connection can take
// a new request, meaning it has not been closed or received or sent a GOAWAY.
func ( c * Conn ) CanTakeNewRequest ( ) bool {
return c . h2cc . CanTakeNewRequest ( )
}
// The first 9 bytes from the server to client over Noise are either an HTTP/2
// settings frame (a normal HTTP/2 setup) or, as we added later, an "early payload"
// header that's also 9 bytes long: 5 bytes (earlyPayloadMagic) followed by 4 bytes
// header that's also 9 bytes long: 5 bytes ( E arlyPayloadMagic) followed by 4 bytes
// of length. Then that many bytes of JSON-encoded tailcfg.EarlyNoise.
// The early payload is optional. Some servers may not send it.
const (
hdrLen = 9 // http2 frame header size; also size of our early payload size header
earlyPayloadMagic = "\xff\xff\xffTS"
hdrLen = 9 // http2 frame header size; also size of our early payload size header
)
// EarlyPayloadMagic is the 5-byte magic prefix that indicates an early payload.
const EarlyPayloadMagic = "\xff\xff\xffTS"
// returnErrReader is an io.Reader that always returns an error.
type returnErrReader struct {
err error // the error to return
@ -129,13 +152,13 @@ func (c *Conn) readHeader() {
setErr ( err )
return
}
if string ( hdr [ : len ( earlyPayloadMagic) ] ) != e arlyPayloadMagic {
if string ( hdr [ : len ( EarlyPayloadMagic) ] ) != E arlyPayloadMagic {
// No early payload. We have to return the 9 bytes read we already
// consumed.
c . reader = io . MultiReader ( bytes . NewReader ( hdr [ : ] ) , c . Conn )
return
}
epLen := binary . BigEndian . Uint32 ( hdr [ len ( e arlyPayloadMagic) : ] )
epLen := binary . BigEndian . Uint32 ( hdr [ len ( E arlyPayloadMagic) : ] )
if epLen > 10 << 20 {
setErr ( errors . New ( "invalid early payload length" ) )
return
@ -162,9 +185,3 @@ func (c *Conn) Close() error {
}
return nil
}
// CanTakeNewRequest reports whether the connection can take a new request,
// meaning it has not been closed or received or sent a GOAWAY.
func ( c * Conn ) CanTakeNewRequest ( ) bool {
return c . h2cc . CanTakeNewRequest ( )
}
Andrew Dunham
1 year ago