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134 lines
3.6 KiB
134 lines
3.6 KiB
/*
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Copyright 2018 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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// Package connrotation implements a connection dialer that tracks and can close
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// all created connections.
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//
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// This is used for credential rotation of long-lived connections, when there's
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// no way to re-authenticate on a live connection.
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package connrotation
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import (
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"context"
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"net"
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"sync"
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)
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// DialFunc is a shorthand for signature of net.DialContext.
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type DialFunc func(ctx context.Context, network, address string) (net.Conn, error)
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// Dialer opens connections through Dial and tracks them.
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type Dialer struct {
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dial DialFunc
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*ConnectionTracker
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}
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// NewDialer creates a new Dialer instance.
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// Equivalent to NewDialerWithTracker(dial, nil).
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func NewDialer(dial DialFunc) *Dialer {
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return NewDialerWithTracker(dial, nil)
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}
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// NewDialerWithTracker creates a new Dialer instance.
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//
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// If dial is not nil, it will be used to create new underlying connections.
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// Otherwise net.DialContext is used.
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// If tracker is not nil, it will be used to track new underlying connections.
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// Otherwise NewConnectionTracker() is used.
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func NewDialerWithTracker(dial DialFunc, tracker *ConnectionTracker) *Dialer {
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if tracker == nil {
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tracker = NewConnectionTracker()
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}
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return &Dialer{
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dial: dial,
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ConnectionTracker: tracker,
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}
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}
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// ConnectionTracker keeps track of opened connections
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type ConnectionTracker struct {
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mu sync.Mutex
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conns map[*closableConn]struct{}
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}
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// NewConnectionTracker returns a connection tracker for use with NewDialerWithTracker
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func NewConnectionTracker() *ConnectionTracker {
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return &ConnectionTracker{
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conns: make(map[*closableConn]struct{}),
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}
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}
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// CloseAll forcibly closes all tracked connections.
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//
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// Note: new connections may get created before CloseAll returns.
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func (c *ConnectionTracker) CloseAll() {
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c.mu.Lock()
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conns := c.conns
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c.conns = make(map[*closableConn]struct{})
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c.mu.Unlock()
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for conn := range conns {
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conn.Close()
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}
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}
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// Track adds the connection to the list of tracked connections,
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// and returns a wrapped copy of the connection that stops tracking the connection
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// when it is closed.
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func (c *ConnectionTracker) Track(conn net.Conn) net.Conn {
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closable := &closableConn{Conn: conn}
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// When the connection is closed, remove it from the map. This will
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// be no-op if the connection isn't in the map, e.g. if CloseAll()
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// is called.
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closable.onClose = func() {
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c.mu.Lock()
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delete(c.conns, closable)
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c.mu.Unlock()
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}
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// Start tracking the connection
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c.mu.Lock()
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c.conns[closable] = struct{}{}
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c.mu.Unlock()
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return closable
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}
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// Dial creates a new tracked connection.
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func (d *Dialer) Dial(network, address string) (net.Conn, error) {
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return d.DialContext(context.Background(), network, address)
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}
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// DialContext creates a new tracked connection.
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func (d *Dialer) DialContext(ctx context.Context, network, address string) (net.Conn, error) {
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conn, err := d.dial(ctx, network, address)
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if err != nil {
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return nil, err
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}
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return d.ConnectionTracker.Track(conn), nil
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}
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type closableConn struct {
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onClose func()
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net.Conn
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}
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func (c *closableConn) Close() error {
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go c.onClose()
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return c.Conn.Close()
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}
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