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// Copyright 2019 The Gitea Authors. All rights reserved.
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file.
// This code is heavily inspired by the archived gofacebook/gracenet/net.go handler
//go:build !windows
package graceful
import (
"fmt"
"net"
"os"
"strconv"
"strings"
"sync"
"code.gitea.io/gitea/modules/log"
"code.gitea.io/gitea/modules/setting"
"code.gitea.io/gitea/modules/util"
)
const (
listenFDs = "LISTEN_FDS"
startFD = 3
)
// In order to keep the working directory the same as when we started we record
// it at startup.
var originalWD, _ = os.Getwd()
var (
once = sync.Once{}
mutex = sync.Mutex{}
providedListeners = []net.Listener{}
activeListeners = []net.Listener{}
)
func getProvidedFDs() (savedErr error) {
// Only inherit the provided FDS once but we will save the error so that repeated calls to this function will return the same error
once.Do(func() {
mutex.Lock()
defer mutex.Unlock()
numFDs := os.Getenv(listenFDs)
if numFDs == "" {
return
}
n, err := strconv.Atoi(numFDs)
if err != nil {
savedErr = fmt.Errorf("%s is not a number: %s. Err: %v", listenFDs, numFDs, err)
return
}
for i := startFD; i < n+startFD; i++ {
file := os.NewFile(uintptr(i), fmt.Sprintf("listener_FD%d", i))
l, err := net.FileListener(file)
if err == nil {
// Close the inherited file if it's a listener
if err = file.Close(); err != nil {
savedErr = fmt.Errorf("error closing provided socket fd %d: %s", i, err)
return
}
providedListeners = append(providedListeners, l)
continue
}
// If needed we can handle packetconns here.
savedErr = fmt.Errorf("Error getting provided socket fd %d: %v", i, err)
return
}
})
return savedErr
}
// CloseProvidedListeners closes all unused provided listeners.
func CloseProvidedListeners() error {
mutex.Lock()
defer mutex.Unlock()
var returnableError error
for _, l := range providedListeners {
err := l.Close()
if err != nil {
log.Error("Error in closing unused provided listener: %v", err)
if returnableError != nil {
returnableError = fmt.Errorf("%v & %v", returnableError, err)
} else {
returnableError = err
}
}
}
providedListeners = []net.Listener{}
return returnableError
}
// GetListener obtains a listener for the local network address. The network must be
// a stream-oriented network: "tcp", "tcp4", "tcp6", "unix" or "unixpacket". It
// returns an provided net.Listener for the matching network and address, or
// creates a new one using net.Listen.
func GetListener(network, address string) (net.Listener, error) {
// Add a deferral to say that we've tried to grab a listener
defer GetManager().InformCleanup()
switch network {
case "tcp", "tcp4", "tcp6":
tcpAddr, err := net.ResolveTCPAddr(network, address)
if err != nil {
return nil, err
}
return GetListenerTCP(network, tcpAddr)
case "unix", "unixpacket":
unixAddr, err := net.ResolveUnixAddr(network, address)
if err != nil {
return nil, err
}
return GetListenerUnix(network, unixAddr)
default:
return nil, net.UnknownNetworkError(network)
}
}
// GetListenerTCP announces on the local network address. The network must be:
// "tcp", "tcp4" or "tcp6". It returns a provided net.Listener for the
// matching network and address, or creates a new one using net.ListenTCP.
func GetListenerTCP(network string, address *net.TCPAddr) (*net.TCPListener, error) {
if err := getProvidedFDs(); err != nil {
return nil, err
}
mutex.Lock()
defer mutex.Unlock()
// look for a provided listener
for i, l := range providedListeners {
if isSameAddr(l.Addr(), address) {
providedListeners = append(providedListeners[:i], providedListeners[i+1:]...)
activeListeners = append(activeListeners, l)
return l.(*net.TCPListener), nil
}
}
// no provided listener for this address -> make a fresh listener
l, err := net.ListenTCP(network, address)
if err != nil {
return nil, err
}
activeListeners = append(activeListeners, l)
return l, nil
}
// GetListenerUnix announces on the local network address. The network must be:
// "unix" or "unixpacket". It returns a provided net.Listener for the
// matching network and address, or creates a new one using net.ListenUnix.
func GetListenerUnix(network string, address *net.UnixAddr) (*net.UnixListener, error) {
if err := getProvidedFDs(); err != nil {
return nil, err
}
mutex.Lock()
defer mutex.Unlock()
// look for a provided listener
for i, l := range providedListeners {
if isSameAddr(l.Addr(), address) {
providedListeners = append(providedListeners[:i], providedListeners[i+1:]...)
activeListeners = append(activeListeners, l)
unixListener := l.(*net.UnixListener)
unixListener.SetUnlinkOnClose(true)
return unixListener, nil
}
}
// make a fresh listener
if err := util.Remove(address.Name); err != nil && !os.IsNotExist(err) {
return nil, fmt.Errorf("Failed to remove unix socket %s: %v", address.Name, err)
}
l, err := net.ListenUnix(network, address)
if err != nil {
return nil, err
}
fileMode := os.FileMode(setting.UnixSocketPermission)
if err = os.Chmod(address.Name, fileMode); err != nil {
return nil, fmt.Errorf("Failed to set permission of unix socket to %s: %v", fileMode.String(), err)
}
activeListeners = append(activeListeners, l)
return l, nil
}
func isSameAddr(a1, a2 net.Addr) bool {
// If the addresses are not on the same network fail.
if a1.Network() != a2.Network() {
return false
}
// If the two addresses have the same string representation they're equal
a1s := a1.String()
a2s := a2.String()
if a1s == a2s {
return true
}
// This allows for ipv6 vs ipv4 local addresses to compare as equal. This
// scenario is common when listening on localhost.
const ipv6prefix = "[::]"
a1s = strings.TrimPrefix(a1s, ipv6prefix)
a2s = strings.TrimPrefix(a2s, ipv6prefix)
const ipv4prefix = "0.0.0.0"
a1s = strings.TrimPrefix(a1s, ipv4prefix)
a2s = strings.TrimPrefix(a2s, ipv4prefix)
return a1s == a2s
}
func getActiveListeners() []net.Listener {
mutex.Lock()
defer mutex.Unlock()
listeners := make([]net.Listener, len(activeListeners))
copy(listeners, activeListeners)
return listeners
}
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