WIP: initial CLI

cmd/dtlspipe/main.go

@@ -0,0 +1,108 @@
+package main
+
+import (
+	"context"
+	"flag"
+	"fmt"
+	"log"
+	"os"
+	"os/signal"
+	"strings"
+	"syscall"
+	"time"
+)
+
+const (
+	ProgName = "dtlspipe"
+)
+
+var (
+	version = "undefined"
+
+	timeout   = flag.Duration("timeout", 10*time.Second, "network operation timeout")
+	idleTime  = flag.Duration("idle-time", 90*time.Second, "max idle time for UDP session")
+	passwdOpt = flag.String("password", "", "password used to derive PSK key")
+)
+
+func usage() {
+	out := flag.CommandLine.Output()
+	fmt.Fprintln(out, "Usage:")
+	fmt.Fprintln(out)
+	fmt.Fprintf(out, "%s [OPTION]... server <BIND ADDRESS> <REMOTE ADDRESS>\n", ProgName)
+	fmt.Fprintf(out, "%s [OPTION]... client <BIND ADDRESS> <REMOTE ADDRESS>\n", ProgName)
+	fmt.Fprintf(out, "%s version\n", ProgName)
+	fmt.Fprintln(out)
+	fmt.Fprintln(out, "Options:")
+	flag.PrintDefaults()
+}
+
+func cmdVersion() int {
+	fmt.Println(version)
+	return 0
+}
+
+func cmdClient(bindAddress, remoteAddress, password string) int {
+	log.Printf("starting dtlspipe client: %s => %s", bindAddress, remoteAddress)
+	defer log.Println("dtlspipe client stopped")
+
+	appCtx, cancel := signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM)
+	defer cancel()
+
+	<-appCtx.Done()
+
+	return 0
+}
+
+func cmdServer(bindAddress, remoteAddress, password string) int {
+	log.Printf("starting dtlspipe server: %s => %s", bindAddress, remoteAddress)
+	defer log.Println("dtlspipe server stopped")
+
+	appCtx, cancel := signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM)
+	defer cancel()
+
+	<-appCtx.Done()
+	return 0
+}
+
+func run() int {
+	flag.CommandLine.Usage = usage
+	flag.Parse()
+	args := flag.Args()
+
+	passwd := os.Getenv("PSK_PASSWD")
+	if passwd == "" {
+		os.Unsetenv("PSK_PASSWD")
+	}
+	if *passwdOpt != "" {
+		passwd = *passwdOpt
+	}
+	if passwd == "" {
+		fmt.Fprintln(os.Stderr)
+		fmt.Fprintln(os.Stderr, "Error: no password option provided and neither PSK_PASSWD environment variable is set")
+		fmt.Fprintln(os.Stderr)
+		return 2
+	}
+
+	switch len(args) {
+	case 1:
+		switch args[0] {
+		case "version":
+			return cmdVersion()
+		}
+	case 3:
+		switch args[0] {
+		case "server":
+			return cmdServer(args[1], args[2], passwd)
+		case "client":
+			return cmdServer(args[1], args[2], passwd)
+		}
+	}
+	usage()
+	return 2
+}
+
+func main() {
+	log.Default().SetFlags(log.Ldate | log.Ltime | log.Lmicroseconds | log.Lshortfile)
+	log.Default().SetPrefix(strings.ToUpper(ProgName) + ": ")
+	os.Exit(run())
+}