Add a bed for the signed-login bus over a real network (research 053 question 8)

test/bed-programs/signed-logins/serve.go

@@ -0,0 +1,95 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"io"
+	"net/http"
+	"os"
+	"os/exec"
+	"os/signal"
+	"strings"
+	"syscall"
+	"time"
+
+	"github.com/nats-io/nats-server/v2/server"
+)
+
+func runServer(args []string) {
+	fs := flag.NewFlagSet("server", flag.ExitOnError)
+	conf := fs.String("conf", "", "config file")
+	fs.Parse(args)
+	opts, err := server.ProcessConfigFile(*conf)
+	if err != nil {
+		fmt.Println("config:", err)
+		os.Exit(1)
+	}
+	opts.NoSigs = true
+	opts.Debug = os.Getenv("Q8DEBUG") != ""
+	s, err := server.NewServer(opts)
+	if err != nil {
+		fmt.Println("server:", err)
+		os.Exit(1)
+	}
+	s.ConfigureLogger()
+	go s.Start()
+	if !s.ReadyForConnections(30 * time.Second) {
+		fmt.Println("not ready")
+		os.Exit(1)
+	}
+	fmt.Println("ready", server.VERSION)
+	ch := make(chan os.Signal, 1)
+	signal.Notify(ch, syscall.SIGINT, syscall.SIGTERM)
+	<-ch
+	s.Shutdown()
+}
+
+// runAgent is a switch for machine C: it drops every packet to and from the peer, and takes the rule away again.
+func runAgent(args []string) {
+	fs := flag.NewFlagSet("agent", flag.ExitOnError)
+	peer := fs.String("peer", "", "address to cut off")
+	fs.Parse(args)
+	nft := func(script string) string {
+		cmd := exec.Command("nft", "-f", "-")
+		cmd.Stdin = strings.NewReader(script)
+		out, err := cmd.CombinedOutput()
+		if err != nil {
+			return fmt.Sprintf("error: %v: %s", err, out)
+		}
+		return "ok"
+	}
+	http.HandleFunc("/block", func(w http.ResponseWriter, r *http.Request) {
+		nft("delete table inet q8cut\n") // ignore: it may not exist
+		io.WriteString(w, nft(fmt.Sprintf(`add table inet q8cut
+add chain inet q8cut in { type filter hook input priority -10; policy accept; }
+add chain inet q8cut out { type filter hook output priority -10; policy accept; }
+add rule inet q8cut in ip saddr %s drop
+add rule inet q8cut out ip daddr %s drop
+`, *peer, *peer)))
+	})
+	http.HandleFunc("/unblock", func(w http.ResponseWriter, r *http.Request) {
+		io.WriteString(w, nft("delete table inet q8cut\n"))
+	})
+	fmt.Println("agent listening on :9099 for peer", *peer)
+	fmt.Println(http.ListenAndServe(":9099", nil))
+}
+
+func runWait(args []string) {
+	fs := flag.NewFlagSet("wait", flag.ExitOnError)
+	url := fs.String("url", "", "url")
+	secs := fs.Int("s", 60, "seconds")
+	fs.Parse(args)
+	end := time.Now().Add(time.Duration(*secs) * time.Second)
+	for time.Now().Before(end) {
+		if r, err := http.Get(*url); err == nil {
+			r.Body.Close()
+			if r.StatusCode == 200 {
+				fmt.Println("up")
+				return
+			}
+		}
+		time.Sleep(500 * time.Millisecond)
+	}
+	fmt.Println("timeout")
+	os.Exit(1)
+}