1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
|
// Copyright 2015 Matthew Holt and The Caddy Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//go:build !unix
package caddy
import (
"context"
"net"
"sync"
"sync/atomic"
"time"
"go.uber.org/zap"
)
func reuseUnixSocket(network, addr string) (any, error) {
return nil, nil
}
func listenTCPOrUnix(ctx context.Context, lnKey string, network, address string, config net.ListenConfig) (net.Listener, error) {
sharedLn, _, err := listenerPool.LoadOrNew(lnKey, func() (Destructor, error) {
ln, err := config.Listen(ctx, network, address)
if err != nil {
return nil, err
}
return &sharedListener{Listener: ln, key: lnKey}, nil
})
if err != nil {
return nil, err
}
return &fakeCloseListener{sharedListener: sharedLn.(*sharedListener), keepAlivePeriod: config.KeepAlive}, nil
}
// fakeCloseListener is a private wrapper over a listener that
// is shared. The state of fakeCloseListener is not shared.
// This allows one user of a socket to "close" the listener
// while in reality the socket stays open for other users of
// the listener. In this way, servers become hot-swappable
// while the listener remains running. Listeners should be
// re-wrapped in a new fakeCloseListener each time the listener
// is reused. This type is atomic and values must not be copied.
type fakeCloseListener struct {
closed int32 // accessed atomically; belongs to this struct only
*sharedListener // embedded, so we also become a net.Listener
keepAlivePeriod time.Duration
}
type canSetKeepAlive interface {
SetKeepAlivePeriod(d time.Duration) error
SetKeepAlive(bool) error
}
func (fcl *fakeCloseListener) Accept() (net.Conn, error) {
// if the listener is already "closed", return error
if atomic.LoadInt32(&fcl.closed) == 1 {
return nil, fakeClosedErr(fcl)
}
// call underlying accept
conn, err := fcl.sharedListener.Accept()
if err == nil {
// if 0, do nothing, Go's default is already set
// and if the connection allows setting KeepAlive, set it
if tconn, ok := conn.(canSetKeepAlive); ok && fcl.keepAlivePeriod != 0 {
if fcl.keepAlivePeriod > 0 {
err = tconn.SetKeepAlivePeriod(fcl.keepAlivePeriod)
} else { // negative
err = tconn.SetKeepAlive(false)
}
if err != nil {
Log().With(zap.String("server", fcl.sharedListener.key)).Warn("unable to set keepalive for new connection:", zap.Error(err))
}
}
return conn, nil
}
// since Accept() returned an error, it may be because our reference to
// the listener (this fakeCloseListener) may have been closed, i.e. the
// server is shutting down; in that case, we need to clear the deadline
// that we set when Close() was called, and return a non-temporary and
// non-timeout error value to the caller, masking the "true" error, so
// that server loops / goroutines won't retry, linger, and leak
if atomic.LoadInt32(&fcl.closed) == 1 {
// we dereference the sharedListener explicitly even though it's embedded
// so that it's clear in the code that side-effects are shared with other
// users of this listener, not just our own reference to it; we also don't
// do anything with the error because all we could do is log it, but we
// expliclty assign it to nothing so we don't forget it's there if needed
_ = fcl.sharedListener.clearDeadline()
if netErr, ok := err.(net.Error); ok && netErr.Timeout() {
return nil, fakeClosedErr(fcl)
}
}
return nil, err
}
// Close stops accepting new connections without closing the
// underlying listener. The underlying listener is only closed
// if the caller is the last known user of the socket.
func (fcl *fakeCloseListener) Close() error {
if atomic.CompareAndSwapInt32(&fcl.closed, 0, 1) {
// There are two ways I know of to get an Accept()
// function to return to the server loop that called
// it: close the listener, or set a deadline in the
// past. Obviously, we can't close the socket yet
// since others may be using it (hence this whole
// file). But we can set the deadline in the past,
// and this is kind of cheating, but it works, and
// it apparently even works on Windows.
_ = fcl.sharedListener.setDeadline()
_, _ = listenerPool.Delete(fcl.sharedListener.key)
}
return nil
}
// sharedListener is a wrapper over an underlying listener. The listener
// and the other fields on the struct are shared state that is synchronized,
// so sharedListener structs must never be copied (always use a pointer).
type sharedListener struct {
net.Listener
key string // uniquely identifies this listener
deadline bool // whether a deadline is currently set
deadlineMu sync.Mutex
}
func (sl *sharedListener) clearDeadline() error {
var err error
sl.deadlineMu.Lock()
if sl.deadline {
switch ln := sl.Listener.(type) {
case *net.TCPListener:
err = ln.SetDeadline(time.Time{})
}
sl.deadline = false
}
sl.deadlineMu.Unlock()
return err
}
func (sl *sharedListener) setDeadline() error {
timeInPast := time.Now().Add(-1 * time.Minute)
var err error
sl.deadlineMu.Lock()
if !sl.deadline {
switch ln := sl.Listener.(type) {
case *net.TCPListener:
err = ln.SetDeadline(timeInPast)
}
sl.deadline = true
}
sl.deadlineMu.Unlock()
return err
}
// Destruct is called by the UsagePool when the listener is
// finally not being used anymore. It closes the socket.
func (sl *sharedListener) Destruct() error {
return sl.Listener.Close()
}
|
