55 lines
1.6 KiB
Go
55 lines
1.6 KiB
Go
// Copyright 2019 The Go Authors. All rights reserved.
|
|
// Use of this source code is governed by a BSD-style
|
|
// license that can be found in the LICENSE file.
|
|
|
|
package proxy
|
|
|
|
import (
|
|
"context"
|
|
"net"
|
|
)
|
|
|
|
// A ContextDialer dials using a context.
|
|
type ContextDialer interface {
|
|
DialContext(ctx context.Context, network, address string) (net.Conn, error)
|
|
}
|
|
|
|
// Dial works like DialContext on net.Dialer but using a dialer returned by FromEnvironment.
|
|
//
|
|
// The passed ctx is only used for returning the Conn, not the lifetime of the Conn.
|
|
//
|
|
// Custom dialers (registered via RegisterDialerType) that do not implement ContextDialer
|
|
// can leak a goroutine for as long as it takes the underlying Dialer implementation to timeout.
|
|
//
|
|
// A Conn returned from a successful Dial after the context has been cancelled will be immediately closed.
|
|
func Dial(ctx context.Context, network, address string) (net.Conn, error) {
|
|
d := FromEnvironment()
|
|
if xd, ok := d.(ContextDialer); ok {
|
|
return xd.DialContext(ctx, network, address)
|
|
}
|
|
return dialContext(ctx, d, network, address)
|
|
}
|
|
|
|
// WARNING: this can leak a goroutine for as long as the underlying Dialer implementation takes to timeout
|
|
// A Conn returned from a successful Dial after the context has been cancelled will be immediately closed.
|
|
func dialContext(ctx context.Context, d Dialer, network, address string) (net.Conn, error) {
|
|
var (
|
|
conn net.Conn
|
|
done = make(chan struct{}, 1)
|
|
err error
|
|
)
|
|
go func() {
|
|
conn, err = d.Dial(network, address)
|
|
close(done)
|
|
if conn != nil && ctx.Err() != nil {
|
|
conn.Close()
|
|
}
|
|
}()
|
|
select {
|
|
case <-ctx.Done():
|
|
err = ctx.Err()
|
|
case <-done:
|
|
}
|
|
return conn, err
|
|
}
|