[jira] [Resolved] (CB-1318) Cordova Callback Logic Not Implemented Correctly - Native Asynchronous Completion Can Call Wrong Logic in Javascript - Requires Non-recurring Unique ID as Outlined

["Braden Shepherdson (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/CB-1318?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Braden Shepherdson resolved CB-1318.
------------------------------------

    Resolution: Fixed

The randomized version is sufficiently robust to mark this as Fixed.

We can decide to change it to add a timestamp for guaranteed uniqueness, or a linear counter for ease of debugging as a separate issue.
                
> Cordova Callback Logic Not Implemented Correctly -  Native Asynchronous Completion Can Call Wrong Logic in Javascript - Requires Non-recurring Unique ID as Outlined
> --------------------------------------------------------------------------------------------------------------------------------------------------------------------
>
>                 Key: CB-1318
>                 URL: https://issues.apache.org/jira/browse/CB-1318
>             Project: Apache Cordova
>          Issue Type: Bug
>          Components: Android, iOS
>    Affects Versions: 2.0.0
>            Reporter: Jim Jarvis
>            Assignee: Braden Shepherdson
>            Priority: Critical
>             Fix For: 2.2.0
>
>
> This bug creates very difficult to find execution anomalies for any asynchronous callback that occurs when the calling context has changed.
> PROBLEM: Cordova callback logic can trigger the callback function of an unrelated call from a different context. When a call from Javascript is made, Cordova generates a new callbackId, adds it to the cordova.callbacks array, and passes it along to the native code. Some time later, when the native code completes the request, it injects javascript to call the callbackSuccess or callbackError function. The respective callback handler looks up the callback attributes from the cordova.callbacks array and executes the original caller's completion function. The problem is each page, or reload of a page, resets the callbackId counter to zero and new calls end up reusing the same callbackId, even though the native code haS not yet completed the prior request. This can occur upon a new page load or reload upon an empty href in an anchor tag. A call to native code from page1.html could trigger the completion routine on page2.html because the native code has no context of the change on the other side of the bridge.
> SOLUTION: Replace the incrementing callbackId with a unique identifier to insure only the caller's completion logic will be called. I have done this with a Pseudo-GUID generator. Fix outlined below:
> // REPLACE THIS LINE in both cordova.2.0.0.js and cordova.ios.js
>         callbackId = service + cordova.callbackId++;    // BUG: incrementing Id's can call unrelated callback logic
> // WITH THIS LINE
>         callbackId = service + ":" + 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function(c) {var r = Math.random()*16|0,v=c=='x'?r:r&0x3|0x8;return v.toString(16);}); // Generate unique callbackID with Pseudo-GUID
> This fix insures no code will execute if the caller's context has changed and is a more well formatted callbackId.

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