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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 "nslcd/systemd"
//
// func main() {
// backend := ...
// os.Exit(int(nslcd_systemd.Main(backend)))
// }
package nslcd_systemd // import "git.lukeshu.com/go/libnslcd/nslcd_systemd"
import (
"fmt"
"net"
"os"
"os/signal"
"sync"
"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(conn *net.UnixConn, backend nslcd_server.Backend) {
defer conn.Close()
cred, err := getpeercred(conn)
if err != nil {
sd_daemon.Log.Debug("Connection from unknown client")
} else {
sd_daemon.Log.Debug(fmt.Sprintf("Connection from pid=%v uid=%v gid=%v",
cred.Pid, cred.Uid, cred.Gid))
}
err = nslcd_server.HandleRequest(backend, conn, conn, cred)
if err != nil {
sd_daemon.Log.Notice(fmt.Sprintf("Error while handling request: %v", err))
}
}
func Main(backend Backend) uint8 {
var err error = nil
sigs := make(chan os.Signal)
signal.Notify(sigs, unix.SIGTERM, unix.SIGHUP)
disable_nss_module()
err = backend.Init()
if err != nil {
sd_daemon.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()
socket, err := get_socket()
if err != nil {
sd_daemon.Log.Err(fmt.Sprintf("%v", err))
sd_daemon.Notification{State: "STOPPING=1"}.Send(false)
return sd_daemon.EXIT_NOTRUNNING
}
defer socket.Close()
sock := make(chan *net.UnixConn)
go func() {
defer sd_daemon.Recover()
for {
conn, err := socket.Accept()
if err != nil {
sd_daemon.Log.Notice(fmt.Sprintf("%v", err))
}
if conn != nil {
sock <- conn.(*net.UnixConn)
}
}
}()
var wg sync.WaitGroup
defer wg.Wait()
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:
sd_daemon.Log.Notice("Received SIGTERM, shutting down")
return sd_daemon.EXIT_SUCCESS
case unix.SIGHUP:
sd_daemon.Log.Notice("Received SIGHUP, reloading")
sd_daemon.Notification{State: "RELOADING=1"}.Send(false)
err := backend.Reload()
if err != nil {
sd_daemon.Log.Notice(fmt.Sprintf("Could not reload backend: %s", err.Error()))
return sd_daemon.EXIT_NOTRUNNING
}
sd_daemon.Notification{State: "READY=1"}.Send(false)
}
case conn := <-sock:
wg.Add(1)
go func() {
defer sd_daemon.Recover()
defer wg.Done()
handler(conn, backend)
}()
}
}
}
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