Advertise suspected NAT type to broker

This compliments the poll the rate adjustment on proxy failures to
address proxy matching issues. Since we cannot determine our NAT type
directly for browser-based proxies, we assume a restricted NAT type if
the datachannel fails to open.

broker.js

@@ -17,10 +17,12 @@ class Broker {
   constructor(config) {
     this.getClientOffer = this.getClientOffer.bind(this);
     this._postRequest = this._postRequest.bind(this);
+    this.setNATType = this.setNATType.bind(this);
 
     this.config = config;
     this.url = config.brokerUrl;
     this.clients = 0;
+    this.natType = "unknown";
     if (0 === this.url.indexOf('localhost', 0)) {
       // Ensure url has the right protocol + trailing slash.
       this.url = 'http://' + this.url;
@@ -64,7 +66,7 @@ class Broker {
         }
       };
       this._xhr = xhr; // Used by spec to fake async Broker interaction
-      var data = {"Version": "1.1", "Sid": id, "Type": this.config.proxyType};
+      var data = {"Version": "1.1", "Sid": id, "Type": this.config.proxyType, "NAT": this.natType};
       return this._postRequest(xhr, 'proxy', JSON.stringify(data));
     });
   }
@@ -93,6 +95,10 @@ class Broker {
     return this._postRequest(xhr, 'answer', JSON.stringify(data));
   }
 
+  setNATType(natType) {
+    this.natType = natType;
+  }
+
   // urlSuffix for the broker is different depending on what action
   // is desired.
   _postRequest(xhr, urlSuffix, payload) {

init-webext.js

@@ -13,6 +13,7 @@ class WebExtUI extends UI {
     this.onMessage = this.onMessage.bind(this);
     this.onDisconnect = this.onDisconnect.bind(this);
     this.initStats();
+    this.initNATType();
     chrome.runtime.onConnect.addListener(this.onConnect);
   }
 
@@ -25,6 +26,14 @@ class WebExtUI extends UI {
     }), 60 * 60 * 1000);
   }
 
+  initNATType() {
+    this.natType = "unknown";
+    // reset NAT type every 24 hours in case proxy location changed
+    setInterval((() => {
+      this.natType = "unknown";
+    }), 24 * 60 * 60 * 1000);
+  }
+
   tryProbe() {
     WS.probeWebsocket(config.relayAddr)
     .then(

package.json

@@ -32,4 +32,4 @@
     "ws": "^3.3.1",
     "xmlhttprequest": "^1.8.0"
   }
-}
\ No newline at end of file
+}

snowflake.js

@@ -21,6 +21,7 @@ class Snowflake {
     this.config = config;
     this.ui = ui;
     this.broker = broker;
+    this.broker.setNATType(ui.natType);
     this.proxyPairs = [];
     this.pollInterval = this.config.defaultBrokerPollInterval;
     if (void 0 === this.config.rateLimitBytes) {
@@ -80,6 +81,9 @@ class Snowflake {
           this.pollInterval =
                 Math.min(this.pollInterval + this.config.pollAdjustment,
                   this.config.slowestBrokerPollInterval);
+          // assume restricted NAT
+          this.ui.natType = "restricted";
+          this.broker.setNATType(this.ui.natType);
         } else {
           // decrease poll interval
           this.pollInterval =

spec/snowflake.spec.js

@@ -36,26 +36,24 @@ class FakeBroker {
       return {};
     });
   }
+  setNATType(natType) {
+  }
 }
 
 describe('Snowflake', function() {
 
   it('constructs correctly', function() {
     var s;
-    s = new Snowflake(config, ui, {
-      fake: 'broker'
-    });
+    s = new Snowflake(config, ui, new FakeBroker());
     expect(s.rateLimit).not.toBeNull();
-    expect(s.broker).toEqual({
-      fake: 'broker'
-    });
+    expect(s.broker).toEqual(new FakeBroker());
     expect(s.ui).not.toBeNull();
     expect(s.retries).toBe(0);
   });
 
   it('sets relay address correctly', function() {
     var s;
-    s = new Snowflake(config, ui, null);
+    s = new Snowflake(config, ui, new FakeBroker());
     s.setRelayAddr('foo');
     expect(s.relayAddr).toEqual('foo');
   });