Вы можете прослушать весь http-трафик через nsIHttpActivityObserver, пример, извлеченный из веб-консоли Firefox:
const Cc = Components.classes;
Cu.import("resource://gre/modules/XPCOMUtils.jsm");
XPCOMUtils.defineLazyServiceGetter(this, "activityDistributor",
"@mozilla.org/network/http-activity-distributor;1",
"nsIHttpActivityDistributor");
let httpTrafficObserver = {
/**
* Begin observing HTTP traffic that we care about,
* namely traffic that originates inside any context that a Heads Up Display
* is active for.
*/
startHTTPObservation: function httpObserverFactory()
{
// creates an observer for http traffic
var self = this;
var httpObserver = {
observeActivity :
function observeActivity(aChannel,
aActivityType,
aActivitySubtype,
aTimestamp,
aExtraSizeData,
aExtraStringData)
{
if (aActivityType ==
activityDistributor.ACTIVITY_TYPE_HTTP_TRANSACTION ||
aActivityType ==
activityDistributor.ACTIVITY_TYPE_SOCKET_TRANSPORT) {
aChannel = aChannel.QueryInterface(Ci.nsIHttpChannel);
let transCodes = this.httpTransactionCodes;
if (aActivitySubtype ==
activityDistributor.ACTIVITY_SUBTYPE_REQUEST_HEADER ) {
let httpActivity = {
url: aChannel.URI.spec,
method: aChannel.requestMethod,
channel: aChannel
};
}
}
},
httpTransactionCodes: {
0x5001: "REQUEST_HEADER",
0x5002: "REQUEST_BODY_SENT",
0x5003: "RESPONSE_START",
0x5004: "RESPONSE_HEADER",
0x5005: "RESPONSE_COMPLETE",
0x5006: "TRANSACTION_CLOSE",
0x804b0003: "STATUS_RESOLVING",
0x804b0007: "STATUS_CONNECTING_TO",
0x804b0004: "STATUS_CONNECTED_TO",
0x804b0005: "STATUS_SENDING_TO",
0x804b000a: "STATUS_WAITING_FOR",
0x804b0006: "STATUS_RECEIVING_FROM"
}
};
this.httpObserver = httpObserver;
activityDistributor.addObserver(httpObserver);
}
};
и http://mxr.mozilla.org/mozilla-central/source/netwerk/protocol/http/nsIHttpActivityObserver.idl