[tor-commits] [snowflake/master] Add a timeout to check if datachannel opened

[cohosh@xxxxxxxxxxxxxx]

commit e77baabdcfd742d6dbc4dbf2a74f21ba6d36ad36
Author: Cecylia Bocovich <cohosh@xxxxxxxxxxxxxx>
Date:   Wed Jul 24 10:52:33 2019 -0400

    Add a timeout to check if datachannel opened
    
    This is similar to the deadlock bug in the proxy-go instances. If the
    proxy-pair sends an answer to the broker, it previously assumed that the
    datachannel would be opened and the pair reused only once the
    datachannel closed. However, sometimes the datachannel never opens due
    to ICE errors or a misbehaving/buggy client causing the proxy to
    infinitely loop and the proxy-pair to remain active.
    
    This commit reuses the pair.running attribute to indicate whether or not
    the datachannel has been opened and sets a timeout to close the
    proxy-pair if it has not been opened by that time.
---
 proxy/proxypair.js | 6 ++++--
 proxy/snowflake.js | 8 +++++++-
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/proxy/proxypair.js b/proxy/proxypair.js
index 6ffa9e5..703ac27 100644
--- a/proxy/proxypair.js
+++ b/proxy/proxypair.js
@@ -85,6 +85,7 @@ class ProxyPair {
   prepareDataChannel(channel) {
     channel.onopen = () => {
       log('WebRTC DataChannel opened!');
+      this.running = true;
       snowflake.state = Snowflake.MODE.WEBRTC_READY;
       snowflake.ui.setActive(true);
       // This is the point when the WebRTC datachannel is done, so the next step
@@ -176,7 +177,6 @@ class ProxyPair {
       clearTimeout(this.timer);
       this.timer = 0;
     }
-    this.running = false;
     if (this.webrtcIsReady()) {
       this.client.close();
     }
@@ -186,6 +186,8 @@ class ProxyPair {
     }
     this.relay = null;
     this.onCleanup();
+    this.active = false;
+    this.running = false;
   }
 
   flush() {
@@ -245,7 +247,7 @@ ProxyPair.prototype.relay = null; // websocket
 
 ProxyPair.prototype.timer = 0;
 
-ProxyPair.prototype.running = true;
+ProxyPair.prototype.running = false; // Whether a datachannel is opened
 
 ProxyPair.prototype.active = false; // Whether serving a client.
 
diff --git a/proxy/snowflake.js b/proxy/snowflake.js
index ae7aa2c..7a242db 100644
--- a/proxy/snowflake.js
+++ b/proxy/snowflake.js
@@ -74,10 +74,16 @@ class Snowflake {
     this.ui.setStatus(msg);
     recv = this.broker.getClientOffer(pair.id);
     recv.then((desc) => {
-      if (pair.running) {
+      if (pair.active) {
         if (!this.receiveOffer(pair, desc)) {
           return pair.active = false;
         }
+        //set a timeout for channel creation 
+        return setTimeout((() => {
+          log('proxypair datachannel timed out waiting for open');
+          pair.close();
+          return pair.active = false;
+        }), 20000); // 20 second timeout
       } else {
         return pair.active = false;
       }

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