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// Copyright (C) 2015-2017 Luke Shumaker <lukeshu@sbcglobal.net>
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
// 02110-1301 USA
// Package nslcd_systemd does the legwork for implementing a systemd
// socket-activated nslcd server.
//
// You just need to implement the Backend interface, then pass it to
// Main, which will return the exit code for the process. Everything
// but the backend is taken care of for you!
//
// package main
//
// import (
// "context"
// "os"
//
// "git.lukeshu.com/go/libnslcd/nslcd_server"
// "git.lukeshu.com/go/libnslcd/nslcd_systemd"
// )
//
// func main() {
// backend := ...
// limits := nslcd_server.Limits{ ... }
// ctx := context.Background()
// os.Exit(int(nslcd_systemd.Main(backend, limits, ctx)))
// }
package nslcd_systemd // import "git.lukeshu.com/go/libnslcd/nslcd_systemd"
import (
"context"
"fmt"
"net"
"os"
"os/signal"
"sync"
"time"
"git.lukeshu.com/go/libnslcd/nslcd_server"
"git.lukeshu.com/go/libsystemd/sd_daemon"
"golang.org/x/sys/unix"
)
type Backend interface {
nslcd_server.Backend
Init() error
Reload() error
Close()
}
func get_socket() (socket net.Listener, err error) {
fds := sd_daemon.ListenFds(true)
if fds == nil {
err = fmt.Errorf("Failed to aquire sockets from systemd")
return
}
if len(fds) != 1 {
err = fmt.Errorf("Wrong number of sockets from systemd: expected %d but got %d", 1, len(fds))
return
}
socket, err = net.FileListener(fds[0])
fds[0].Close()
return
}
func getpeercred(conn *net.UnixConn) (cred unix.Ucred, err error) {
rawconn, err := conn.SyscallConn()
if err != nil {
return
}
var _cred *unix.Ucred
var _err error
err = rawconn.Control(func(fd uintptr) {
_cred, _err = unix.GetsockoptUcred(int(fd), unix.SOL_SOCKET, unix.SO_PEERCRED)
})
if err != nil {
return
}
if _err != nil {
err = _err
return
}
cred = *_cred
return
}
func handler(backend nslcd_server.Backend, limits nslcd_server.Limits, conn *net.UnixConn, cid int, ctx context.Context) {
defer conn.Close()
ctx, cancel := context.WithCancel(ctx)
defer cancel()
log := PrefixLogger{
Prefix: fmt.Sprintf("[%v] ", cid),
Logger: nslcd_server.LoggerFromContext(ctx),
}
ctx = context.WithValue(ctx, nslcd_server.LoggerKey, log)
defer log.Info("Connection closed")
cred, err := getpeercred(conn)
if err != nil {
log.Info("Connection from unknown client")
} else {
log.Info(fmt.Sprintf("Connection from pid=%v uid=%v gid=%v",
cred.Pid, cred.Uid, cred.Gid))
ctx = context.WithValue(ctx, nslcd_server.PeerCredKey, cred)
}
err = nslcd_server.HandleRequest(backend, limits, conn, ctx)
if err != nil {
log.Notice(fmt.Sprintf("Error while handling request: %v", err))
}
}
func Main(backend Backend, limits nslcd_server.Limits, ctx context.Context) uint8 {
defer sd_daemon.Recover()
var err error = nil
sigs := make(chan os.Signal)
signal.Notify(sigs, unix.SIGTERM, unix.SIGHUP)
log := nslcd_server.LoggerFromContext(ctx)
disable_nss_module(log)
err = backend.Init()
if err != nil {
log.Err(fmt.Sprintf("Could not initialize backend: %v", err))
sd_daemon.Notification{State: "STOPPING=1"}.Send(false)
return sd_daemon.EXIT_FAILURE
}
defer backend.Close()
var wg sync.WaitGroup
defer wg.Wait()
socket, err := get_socket()
if err != nil {
log.Err(fmt.Sprintf("%v", err))
sd_daemon.Notification{State: "STOPPING=1"}.Send(false)
return sd_daemon.EXIT_NOTRUNNING
}
defer func() { socket.(*net.UnixListener).SetDeadline(time.Now()) }()
ctx, cancel := context.WithCancel(ctx)
defer cancel()
socket_error := make(chan error)
wg.Add(1)
go func() {
defer sd_daemon.Recover()
defer wg.Done()
id := 0
var tempDelay time.Duration
last := false
for !last {
conn, err := socket.Accept()
if err != nil {
if ne, ok := err.(net.Error); ok && ne.Timeout() {
last = true
} else if ne, ok := err.(net.Error); ok && ne.Temporary() {
log.Notice(fmt.Sprintf("temporary error %v", err))
if tempDelay == 0 {
tempDelay = 5 * time.Millisecond
} else {
tempDelay *= 2
}
if max := 1 * time.Second; tempDelay > max {
tempDelay = max
}
time.Sleep(tempDelay)
} else {
socket_error <- err
last = true
}
}
if conn != nil {
wg.Add(1)
id++
go func(conn *net.UnixConn, id int) {
defer sd_daemon.Recover()
defer wg.Done()
handler(backend, limits, conn, id, ctx)
}(conn.(*net.UnixConn), id)
}
}
}()
defer sd_daemon.Notification{State: "STOPPING=1"}.Send(false)
sd_daemon.Notification{State: "READY=1"}.Send(false)
for {
select {
case sig := <-sigs:
switch sig {
case unix.SIGTERM:
log.Notice("Received SIGTERM, shutting down")
return sd_daemon.EXIT_SUCCESS
case unix.SIGHUP:
log.Notice("Received SIGHUP, reloading")
sd_daemon.Notification{State: "RELOADING=1"}.Send(false)
err := backend.Reload()
if err != nil {
log.Notice(fmt.Sprintf("Could not reload backend: %v", err))
return sd_daemon.EXIT_NOTRUNNING
}
sd_daemon.Notification{State: "READY=1"}.Send(false)
}
case <-ctx.Done():
log.Err(fmt.Sprintf("Context was canceled, shutting down: %v", ctx.Err()))
return sd_daemon.EXIT_FAILURE
case err = <-socket_error:
log.Err(fmt.Sprintf("%v", err))
return sd_daemon.EXIT_NETWORK
}
}
}
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