Added CLI args parsing

README.md

@@ -10,9 +10,13 @@
 ```
 cd content-dht-provide-find
 make
-./dht-interop
+./dht-interop -b ../util/private_key.bin
 ```
 
+`-b` means bootstrap mode.  In this example, the go program is always the bootstrap node, so `-b` is always required.
+
+Note that the node ID of `dht-interop` is always `Qm...6aJ9oRuEzWa` because it is being read in from `../util/private_key.bin` (a private key marshalled to X.509 generated by `util/private-key-gen`).  This is to keep the peer id of the bootstrap server stable across invocations.
+
 **Second terminal:**  run the command printed out by dht-interop, replacing 127.0.0.1 with the IP of the server where dht-interop is listening.  Example:
 
 First time only:
@@ -26,7 +30,6 @@ Running the Node.js program:
 node js-dht-test/index.js /ip4/127.0.0.1/tcp/9876/ipfs/QmehVYruznbyDZuHBV4vEHESpDevMoAovET6aJ9oRuEzWa
 ```
 
-Note that the node ID of `dht-interop` is always `Qm...6aJ9oRuEzWa` because it is being read in from `util/private_key.bin` (a private key marshalled to X.509 generated by `util/private-key-gen`).  This is to keep the peer id of the bootstrap server stable across invocations.
 
 
 ## Demo 2:  PubSub

content-dht-provide-find/dht-interop.go

@@ -63,14 +63,37 @@ func handleConn(conn net.Conn) {
 	}
 }
 
+func parseArgs() (bool, string) {
+	usage := fmt.Sprintf("Usage: %s [-b] [PRIVATE_KEY]\n\n-b is bootstrap mode (creates DHT)\nPRIVATE_KEY is the path to a private key like '../util/private_key.bin'\n", os.Args[0])
+	var bBootstrap bool = false
+	var privKeyFilePath string
+	var args []string = os.Args[1:]
+	if (len(args) == 0) || (len(args) > 2) {
+		fmt.Printf("Error: wrong number of arguments\n\n%s", usage)
+		os.Exit(1)
+	}
+	if args[0] == "-b" {
+		bBootstrap = true
+		args = args[1:]
+	}
+	privKeyFilePath = args[0]
+	return bBootstrap, privKeyFilePath
+}
+
 func main() {
 	ctx := context.Background()
 
+	bBootstrap, privKeyFilePath := parseArgs()
+	if !bBootstrap {
+		fmt.Printf("Error: bootstrap mode required in this example")
+		os.Exit(1)
+	}
+
 	//
 	// Read the private key
 	//
 	var privBytes []byte
-	privBytes, err := ioutil.ReadFile("../util/private_key.bin")
+	privBytes, err := ioutil.ReadFile(privKeyFilePath)
 	if err != nil {
 		fmt.Println("ioutil.ReadFile:  failed:  %v", err)
 		panic(err)