go.mod

@@ -1,3 +0,0 @@
-module tlsserver
-
-go 1.21.6

tlsserver.go

@@ -2,109 +2,34 @@ package main
 
 import (
 	"crypto/tls"
-	"flag"
-	"fmt"
 	"log"
 	"net"
+	"flag"
+	"fmt"
 	"os"
 	"os/exec"
-	"os/user"
-	"strconv"
-	"syscall"
 )
 
 var (
 	cfile = flag.String("cert", "cert.pem", "Certificate file in PEM format")
 	kfile = flag.String("key", "key.pem", "Key file in PEM format")
-	port  = flag.String("port", ":1234", "Port to bind to")
-	uid   = flag.Int("uid", -1, "UID to run under")
+	port = flag.Int("port", 1234, "Port to bind to")
 	args []string
+	nargs int
 )
 
-const TLSSERVER = "[tlsserver]"
-
 func main() {
-	flag.Parse()
 
-	if flag.NArg() < 1 {
+	flag.Parse()
+	 args = flag.Args()
+	nargs = flag.NArg()
+	if nargs < 1 {
 		fmt.Println("Usage: tlsserver [options] cmd [flags for cmd]")
 		fmt.Println("options:")
 		flag.PrintDefaults()
 		os.Exit(1)
 	}
 
-	if os.Args[0] == TLSSERVER {
-		log.Fatal(serve())
-	} else {
-		log.Fatal(exc())
-	}
-}
-
-func exc() error {
-	if *uid < 0 {
-		return serve()
-	}
-
-	// Collect information about the user
-	user, err := user.LookupId(strconv.Itoa(*uid))
-	if err != nil {
-		return err
-	}
-
-	// Get the primary and secondary groups
-	gids := []int{}
-
-	gid, err := strconv.Atoi(user.Gid)
-	if err != nil {
-		return fmt.Errorf("couldn't parse user.Gid, strconv.Atoi(%s): %v", user.Gid, err)
-	}
-
-	if sgids, err := user.GroupIds(); err != nil {
-		log.Println("weird, couldn't get supplimentary groups: %v", err)
-	} else {
-		for _, s := range sgids {
-			v, e := strconv.Atoi(s)
-			if e != nil {
-				log.Println("weird, strconv.Atoi(%s): %v", s, e)
-				continue
-			} else if v != gid {
-				gids = append(gids, v)
-			}
-		}
-	}
-
-	if err := setgid(gid); err != nil {
-		return err
-	}
-
-	if len(gids) > 0 {
-		if err = syscall.Setgroups(gids); err != nil {
-			return fmt.Errorf("syscall.Setgroups: %w", err)
-		}
-	}
-
-	if err = setuid(*uid); err != nil {
-		return err
-	}
-
-	// Setup the arguments that are needed
-	args := []string{TLSSERVER} // name of the command
-
-	for _, arg := range []string{"cert", "key", "port"} {
-		fl := flag.Lookup(arg)
-		// Only set the flag if it's value are different from the default
-		if fl != nil && fl.Value.String() != fl.DefValue {
-			args = append(args, "-"+arg, fl.Value.String())
-		}
-	}
-	args = append(args, flag.Args()...)
-
-	return syscall.Exec(os.Args[0], args, os.Environ())
-}
-
-func serve() error {
-	args = flag.Args()
-
 	// setup certs etc. for TLS-socket
 	tconf := new(tls.Config)
 	cert, err := tls.LoadX509KeyPair(*cfile, *kfile)
@@ -117,7 +42,8 @@ func serve() error {
 	tconf.BuildNameToCertificate()
 
 	// start listening
-	sock, err := tls.Listen("tcp", *port, tconf)
+	sport := fmt.Sprintf(":%d", *port)
+	sock, err := tls.Listen("tcp", sport , tconf)
 	if err != nil {
 		fmt.Println("error with tcp-socket:", err)
 		os.Exit(3)
@@ -132,11 +58,11 @@ func serve() error {
 			continue
 		}
 		log.Println("Got connection:", conn.RemoteAddr())
-		go handleConnection(conn, args...)
+		go handleConnection(conn)
 	}
 }
 
-func handleConnection(conn net.Conn, args ...string) {
+func handleConnection(conn net.Conn) {
 	defer conn.Close()
 
 	// setup cmd
@@ -145,51 +71,9 @@ func handleConnection(conn net.Conn, args ...string) {
 	cmd.Stdin = conn
 	cmd.Stdout = conn
 	cmd.Stderr = os.Stderr
-
-	// prepare environment according to tcp-environ(5)
-	lh, lp, err := net.SplitHostPort(conn.LocalAddr().String())
+	err := cmd.Run()
 	if err != nil {
-		log.Println("net.SplitHostPort(conn.LocalAddr()):", err)
-		return
-	}
-
-	rh, rp, err := net.SplitHostPort(conn.RemoteAddr().String())
-	if err != nil {
-		log.Println("net.SplitHostPort(conn.RemoteAddr()):", err)
-		return
-	}
-
-	cmd.Env = make([]string, 0)
-	cmd.Env = append(cmd.Env, "PATH="+os.Getenv("PATH"))
-	cmd.Env = append(cmd.Env, "PROTO=TCP")
-	cmd.Env = append(cmd.Env, "TCPLOCALIP="+lh)
-	cmd.Env = append(cmd.Env, "TCPLOCALPORT="+lp)
-	cmd.Env = append(cmd.Env, "TCPREMOTEIP="+rh)
-	cmd.Env = append(cmd.Env, "TCPREMOTEPORT="+rp)
-
-	err = cmd.Run()
-	if err != nil {
-		log.Println("after Run: ", err)
+		log.Println(err)
 	}
 	log.Println("Done with connection", conn.RemoteAddr())
 }
-
-// Since go1.4 the setgid syscall is deliberatelly not supported anymore, as it
-// only applies to the calling thread.  So we try this here:
-func setgid(gid int) error {
-	// RawSyscall(trap, a1, a2, a3 uintptr) (r1, r2 uintptr, err Errno)
-	_, _, e := syscall.RawSyscall(syscall.SYS_SETGID, uintptr(gid), 0, 0)
-	if e != 0 {
-		return fmt.Errorf("setgid: %w", e)
-	}
-	return nil
-}
-
-func setuid(uid int) error {
-	// RawSyscall(trap, a1, a2, a3 uintptr) (r1, r2 uintptr, err Errno)
-	_, _, e := syscall.RawSyscall(syscall.SYS_SETUID, uintptr(uid), 0, 0)
-	if e != 0 {
-		return fmt.Errorf("setuid: %w", e)
-	}
-	return nil
-}