From db55f3f83cc1203891b537e0e525037f6856b11f Mon Sep 17 00:00:00 2001
From: "John \"Elwin\" Edwards" <elwin@rlgallery.org>
Date: Tue, 15 May 2012 16:26:28 -0700
Subject: [PATCH] webtty.js: check message order.

Implement checking the numbers of the client's messages on the server.
Fixing out-of-ordering isn't implemented because the problem hasn't
been observed yet, though it likely will once actual network transit
is involved.
---
 webtty.js | 22 +++++++++++++++-------
 1 file changed, 15 insertions(+), 7 deletions(-)

diff --git a/webtty.js b/webtty.js
index e06073d..26ff927 100755
--- a/webtty.js
+++ b/webtty.js
@@ -38,8 +38,10 @@ function TermSession(sessid, h, w) {
   /* Eventually we'll need to make sure the sessid isn't in use yet. */
   this.sessid = sessid;
   this.alive = true;
-  this.data = [];
-  this.nsend = 0;
+  this.data = []; // Buffer for the process' output.
+  this.nsend = 0; // Number to use for the next message sent.
+  this.nrecv = 0; // Number expected on the next message received.
+  this.msgQ = []; // Queue for messages that arrived out of order.
   this.child.stdout.on("data", function (buf) {
     ss.data.push(buf);
   });
@@ -52,10 +54,16 @@ function TermSession(sessid, h, w) {
     /* Wait for all the data to get collected */
     setTimeout(ss.cleanup, 1000);
   });
-  this.write = function (data) {
-    if (this.alive)
-      this.child.stdin.write(data);
-    /* Otherwise, throw some kind of exception? */
+  this.write = function (data, n) {
+    if (!this.alive) {
+      /* Throw some kind of exception? */
+      return;
+    }
+    if (n !== this.nrecv) {
+      console.log("Session " + this.sessid + ": Expected message " + this.nrecv + ", got " + n);
+    }
+    this.nrecv = n + 1;
+    this.child.stdin.write(data);
   };
   this.read = function () {
     if (this.data.length == 0)
@@ -303,7 +311,7 @@ function handler(req, res) {
             return;
           }
           keybuf = new Buffer(hexstr, "hex");
-          cterm.write(keybuf);
+          cterm.write(keybuf, formdata["n"]);
         }
         readFeed(res, cterm);
       }