/
activation.go
119 lines (111 loc) · 3.06 KB
/
activation.go
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package activation
import (
"errors"
"fmt"
"log"
"net"
"os"
"strconv"
"strings"
"syscall"
)
const (
// https://www.freedesktop.org/software/systemd/man/sd_listen_fds.html
listenFdsStart = 3
)
var listeners []net.Listener
func init() {
var err error
if listeners, err = activationListeners(); err != nil {
log.Println("warning: systemd socket activation disabled")
}
}
// Listen returns the net.Listener matching the given address.
func Listen(addr string) (net.Listener, error) {
_, port, err := net.SplitHostPort(addr)
if err != nil {
return nil, fmt.Errorf("failed to parse %s addr: %v", addr, err)
}
for _, l := range listeners {
_, p, err := net.SplitHostPort(l.Addr().String())
if err != nil {
return nil, fmt.Errorf("failed to parse %s addr: %v", l.Addr().String(), err)
}
if port == p {
return l, nil
}
}
return nil, fmt.Errorf("%s addr not found", addr)
}
func activationListeners() ([]net.Listener, error) {
files, err := getFiles()
if err != nil {
return nil, err
}
listeners := make([]net.Listener, len(files))
for i, f := range files {
listener, err := net.FileListener(f)
if err != nil {
return nil, fmt.Errorf("failed to init new file listener: %v", err)
}
if err = f.Close(); err != nil {
return nil, fmt.Errorf("failed to close %s file: %v", f.Name(), err)
}
listeners[i] = listener
}
return listeners, nil
}
func getFiles() ([]*os.File, error) {
err := checkEnv()
if err != nil {
return nil, err
}
listenPid, err := strconv.Atoi(os.Getenv("LISTEN_PID"))
if err != nil {
return nil, fmt.Errorf("failed to parse LISTEN_PID as int: %v", err)
}
if listenPid != os.Getpid() {
return nil, fmt.Errorf("bad pid (LISTEN_PID=%d, pid=%d)", listenPid, os.Getpid())
}
listenFds, err := strconv.Atoi(os.Getenv("LISTEN_FDS"))
if err != nil {
return nil, fmt.Errorf("failed to parse LISTEN_FDS as int: %v", err)
}
var listenFdNames []string
if _, ok := os.LookupEnv("LISTEN_FDS"); ok {
listenFdNames = strings.Split(os.Getenv("LISTEN_FDNAMES"), ":")
if err = os.Unsetenv("LISTEN_FDNAMES"); err != nil {
return nil, fmt.Errorf("failed to unset env LISTEN_FDNAMES: %v", err)
}
}
if err = os.Unsetenv("LISTEN_FDS"); err != nil {
return nil, fmt.Errorf("failed to unset env LISTEN_PID: %v", err)
}
if err = os.Unsetenv("LISTEN_FDNAMES"); err != nil {
return nil, fmt.Errorf("failed to unset env LISTEN_PID: %v", err)
}
files := make([]*os.File, 0, listenFds)
for fd := listenFdsStart; fd < listenFdsStart+listenFds; fd++ {
// http://man7.org/linux/man-pages/man2/fcntl.2.html
syscall.CloseOnExec(fd)
name := "LISTEN_FD_" + strconv.Itoa(fd)
if listenFdNames != nil {
offset := fd - listenFdsStart
if offset < len(listenFdNames) && len(listenFdNames[offset]) > 0 {
name = listenFdNames[offset]
}
}
files = append(files, os.NewFile(uintptr(fd), name))
}
return files, nil
}
func checkEnv() error {
_, ok := os.LookupEnv("LISTEN_PID")
if !ok {
return errors.New("LISTEN_PID not set")
}
if _, ok = os.LookupEnv("LISTEN_FDS"); !ok {
return errors.New("LISTEN_FDS not set")
}
return nil
}