如何识别源自"hiddenDOMWindow"的请求? [英] How to identify requests originating from the `hiddenDOMWindow`?

问题描述

我可以使用哪些事件侦听器来标识来自firefox插件中的hiddenDOMWindow(或其中的iframe)的请求?例如，在"http-on-modify-request"事件中发送请求之前，我需要执行此操作.

What event-listeners can I use to identify requests originating from the hiddenDOMWindow (or an iframe within it) in a firefox-addon? I need to do this BEFORE the request has been sent, in the "http-on-modify-request" event, for example.

我尝试过的事情:

• 注册全局"http-on-modify-request"；但我无法区分源窗口
• 将侦听器添加到hiddenDOMWindow本身；但我找不到任何加载前事件
• 将侦听器添加到hiddenDOMWindow.document;没有加载前事件
• 将侦听器添加到已创建的hiddenDOMWindow.document.iframe中；没有加载前事件

推荐答案

首先，您需要从nsIChannel获取DOMWindow:

function getDOMWindowFromChannel(ch) {
    var wp;
    try {
        if (ch.loadGroup && ch.loadGroup.groupObserver) {
            wp = ch.loadGroup.groupObserver.
                 QueryInterface(Ci.nsIWebProgress);
        }
    } catch (ex) {}
    try {
        if (!wp) {
            wp = ch.notificationCallbacks.
                 getInterface(Ci.nsIWebProgress);
        }
    }
    catch (ex) {}
    try {
        if (wp) {
            return wp.DOMWindow || null;
        }
    }
    catch (ex) {}
    return null;
}

现在您有了一个DOMWindow，您需要找到该DOMWindow的顶层窗口，这并不是很直观:

Now that you got a DOMWindow, you need to find the top level window for that DOMWindow, which is not really intuitive:

function getToplevelWindow(win) {
    try {
        return win.QueryInterface(Ci.nsIInterfaceRequestor).
               getInterface(Ci.nsIWebNavigation).
               QueryInterface(Ci.nsIDocShell).
               treeOwner.
               QueryInterface(Ci.nsIInterfaceRequestor).
               getInterface(Ci.nsIXULWindow).
               docShell.
               contentViewer.DOMDocument.defaultView;
    }
    catch (ex) {
        // Likely already a top-level window.
        return win;
    }
}

现在，让我们来制作和安装观察器，将它们组合在一起:

Now, lets craft and install the observer, bringing all together:

function observe(channel, topic, data) {

    if (!(channel instanceof Ci.nsIChannel)) {
        return;
    }
    var win = getDOMWindowFromChannel(channel);
    if (!win) {
        return;
    }
    var topWin = getToplevelWindow(win);
    if (topWin.location.href.indexOf("chrome://browser/content/hiddenWindow") != 0) {
        return;
    }
    // do stuff, e.g.
    console.log(topWin.location.href);
}

Services.obs.addObserver(observe, "http-on-modify-request", false);

应该注意的是，并不是所有的请求都是nsIChannel，并不是所有的nsIChannel实际上都有关联的DOMWindow或实际的loadGroup(例如，后台请求)，因此是所有这些try catch块.

It should be noted that not all requests are nsIChannel and not all nsIChannel actually have a DOMWindow or real loadGroup associated (e.g. background requests), hence all those try catch blocks.

此外，别忘了在某个时候再次删除观察者，而我已经跳过了. ;)

Also, don't forget to remove the observer again at some point, which I skipped. ;)

最后，这是一些实际测试此代码的代码(我在about:newtab选项卡上以Scratchpad的身份运行了整个程序，该选项卡恰好具有附加组件的chrome特权):

And lastly, here is some code to actually test this (I ran the whole thing as a Scratchpad on an about:newtab tab, which happens to have chrome privileges just like add-ons):

var hw = Services.appShell.hiddenDOMWindow;
var iframe = hw.document.createElement("iframe");
hw.document.documentElement.appendChild(iframe);
var r = iframe.contentWindow.XMLHttpRequest();
r.open("GET", "http://example.org/");
r.send();

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