cmd/ssh-chat: Accept multiple --identity keys

Fixes #401

cmd/ssh-chat/cmd.go

@@ -30,7 +30,7 @@ var Version string = "dev"
 type Options struct {
 	Admin      string   `long:"admin" description:"File of public keys who are admins."`
 	Bind       string   `long:"bind" description:"Host and port to listen on." default:"0.0.0.0:2022"`
-	Identity   string `short:"i" long:"identity" description:"Private key to identify server with." default:"~/.ssh/id_rsa"`
+	Identity   []string `short:"i" long:"identity" description:"Private key to identify server with." default:"~/.ssh/id_rsa"`
 	Log        string   `long:"log" description:"Write chat log to this file."`
 	Motd       string   `long:"motd" description:"Optional Message of the Day file."`
 	Pprof      int      `long:"pprof" description:"Enable pprof http server for profiling."`
@@ -102,7 +102,12 @@ func main() {
 		message.SetLogger(os.Stderr)
 	}
 
-	privateKeyPath := options.Identity
+	auth := sshchat.NewAuth()
+	config := sshd.MakeAuth(auth)
+	config.ServerVersion = "SSH-2.0-Go ssh-chat"
+	// FIXME: Should we be using config.NoClientAuth = true by default?
+
+	for _, privateKeyPath := range options.Identity {
 		if strings.HasPrefix(privateKeyPath, "~/") {
 			user, err := user.Current()
 			if err == nil {
@@ -115,11 +120,9 @@ func main() {
 			fail(3, "Failed to read identity private key: %v\n", err)
 		}
 
-	auth := sshchat.NewAuth()
-	config := sshd.MakeAuth(auth)
 		config.AddHostKey(signer)
-	config.ServerVersion = "SSH-2.0-Go ssh-chat"
-	// FIXME: Should we be using config.NoClientAuth = true by default?
+		fmt.Printf("Added server identity: %s\n", sshd.Fingerprint(signer.PublicKey()))
+	}
 
 	s, err := sshd.ListenSSH(options.Bind, config)
 	if err != nil {