webRequest.onAuthRequired

Fired when the server sends a 401 or 407 status code (that is, when the server is asking the client to provide authentication credentials, such as a username and password).

The listener can respond in one of four different ways:

Take no action

The listener can do nothing, just observing the request. If this happens, it will have no effect on the handling of the request, and the browser will probably just ask the user to log in.

Cancel the request

The listener can cancel the request. If they do this, then authentication will fail, and the user will not be asked to log in. Extensions can cancel requests as follows:

• in addListener, pass "blocking" in the extraInfoSpec parameter
• in the listener itself, return an object with a cancel property set to true

Provide credentials synchronously

If credentials are available synchronously, the extension can supply them synchronously. If the extension does this, then the browser will attempt to log in with the given credentials. The listener can provide credentials synchronously as follows:

• in addListener, pass "blocking" in the extraInfoSpec parameter
• in the listener, return an object with an authCredentials property set to the credentials to supply

Provide credentials asynchronously

The extension might need to fetch credentials asynchronously. For example, the extension might need to fetch credentials from storage, or ask the user. In this case, the listener can supply credentials asynchronously as follows:

• in addListener, pass "blocking" in the extraInfoSpec parameter
• in the listener, return a Promise that is resolved with an object containing an authCredentials property, set to the credentials to supply

See Examples.

If you use "blocking" you must have the "webRequestBlocking" API permission in your manifest.json.

If your extension provides bad credentials, then the listener will be called again. For this reason, take care not to enter an infinite loop by repeatedly providing bad credentials.

Proxy authorization

In general, Firefox does not fire webRequest events for system requests, such as browser or extension upgrades, or search engine queries. To enable proxy authorization to work smoothly for system requests, from version 57 Firefox implements an exception to this.

If an extension has the "webRequest", "webRequestBlocking", "proxy", and "<all_urls>" permissions, then it will be able to use onAuthRequired to supply credentials for proxy authorization (but not for normal web authorization). The listener will not be able to cancel system requests or make any other modifications to any system requests.

Syntax

browser.webRequest.onAuthRequired.addListener(
  listener,                    // function
  filter,                      //  object
  extraInfoSpec                //  optional array of strings
)
browser.webRequest.onAuthRequired.removeListener(listener)
browser.webRequest.onAuthRequired.hasListener(listener)

Events have three functions:

addListener(callback, filter, extraInfoSpec)

Adds a listener to this event.

removeListener(listener)

Stop listening to this event. The listener argument is the listener to remove.

hasListener(listener)

Check whether listener is registered for this event. Returns true if it is listening, false otherwise.

addListener syntax

Parameters

callback

A function that will be called when this event occurs. The function will be passed the following arguments:

details

object. Details about the request. See details below.

Returns: webRequest.BlockingResponse or a Promise.

• To handle the request synchronously, include "blocking" in the extraInfoSpec parameter and return a BlockingResponse object, with its cancel or its authCredentials properties set.
• To handle the request asynchronously, include "blocking" in the extraInfoSpec parameter and return a Promise that is resolved with a BlockingResponse object, with its cancel or its authCredentials properties set.

filter

webRequest.RequestFilter. A filter that restricts the events that will be sent to this listener.

extraInfoSpecOptional

array of string. Extra options for the event. You can pass any of the following values:

• "blocking": make the request block, so you can cancel the request or supply authentication credentials
• "responseHeaders": include responseHeaders in the details object passed to the listener

Additional objects

details

challenger

object. The server requesting authentication. This is an object with the following properties:

host

string. The server's hostname.
Warning: Unlike Chrome, Firefox will return the requested host instead of the proxy requesting the authentication, even if isProxy is true.

port

integer. The server's port number.

cookieStoreId

string. If the request is from a tab open in a contextual identity, the cookie store ID of the contextual identity.

frameId

integer. This is 0 if the request happens in the main frame; a positive value is the ID of a subframe in which the request happens. If the document of a (sub-)frame is loaded (type is main_frame or sub_frame), frameId indicates the ID of this frame, not the ID of the outer frame. Frame IDs are unique within a tab.

incognito

boolean. Whether the request is from a private browsing window.

isProxy

boolean. true for Proxy-Authenticate, false for WWW-Authenticate. Note: webRequest.onAuthRequired is only called for HTTP and HTTPS/SSL proxy servers requiring authentication, and not for SOCKS proxy servers requiring authentication.

method

string. Standard HTTP method (For example, "GET" or "POST").

parentFrameId

integer. ID of the frame that contains the frame which sent the request. Set to -1 if no parent frame exists.

proxyInfo

object. This property is present only if the request is being proxied. It contains the following properties:

host

string. The hostname of the proxy server.

port

integer. The port number of the proxy server.

type

string. The type of proxy server. One of:

• "http": HTTP proxy (or SSL CONNECT for HTTPS)
• "https": HTTP proxying over TLS connection to proxy
• "socks": SOCKS v5 proxy
• "socks4": SOCKS v4 proxy
• "direct": no proxy
• "unknown": unknown proxy

username

string. Username for the proxy service.

proxyDNS

boolean. True if the proxy will perform domain name resolution based on the hostname supplied, meaning that the client should not do its own DNS lookup.

failoverTimeout

integer. Failover timeout in seconds. If the connection fails to connect the proxy server after this number of seconds, the next proxy server in the array returned from FindProxyForURL() will be used.

realmOptional

string. The authentication realm provided by the server, if there is one.

requestId

string. The ID of the request. Request IDs are unique within a browser session, so you can use them to relate different events associated with the same request.

responseHeadersOptional

webRequest.HttpHeaders. The HTTP response headers that were received along with this response.

scheme

string. The authentication scheme: "basic" or "digest".

statusCode

integer. Standard HTTP status code returned by the server.

statusLine

string. HTTP status line of the response or the 'HTTP/0.9 200 OK' string for HTTP/0.9 responses (i.e., responses that lack a status line) or an empty string if there are no headers.

tabId

integer. ID of the tab in which the request takes place. Set to -1 if the request isn't related to a tab.

thirdParty

boolean. Indicates whether the request and its content window hierarchy are third party.

timeStamp

number. The time when this event fired, in milliseconds since the epoch.

type

webRequest.ResourceType. The type of resource being requested: for example, "image", "script", "stylesheet".

url

string. Target of the request.

urlClassification

object. The type of tracking associated with the request, if with the request has been classified by Firefox Tracking Protection. This is an object with the following properties:

firstParty

array of strings. Classification flags for the request's first party.

thirdParty

array of strings. Classification flags for the request or its window hierarchy's third parties.

The classification flags include:

• fingerprinting and fingerprinting_content: indicates the request is involved in fingerprinting. fingerprinting_content indicates the request is loaded from an origin that has been found to fingerprint but is not considered to participate in tracking, such as a payment provider.
• cryptomining and cryptomining_content: similar to the fingerprinting category but for cryptomining resources.
• tracking, tracking_ad, tracking_analytics, tracking_social, and tracking_content: indicates the request is involved in tracking. tracking is any generic tracking request, the ad, analytics, social, and content suffixes identify the type of tracker.
• any_basic_tracking: a meta flag that combines any tracking and fingerprinting flags, excluding tracking_content and fingerprinting_content.
• any_strict_tracking: a meta flag that combines any tracking and fingerprinting flags, including tracking_content and fingerprinting_content.
• any_social_tracking: a meta flag that combines any social tracking flags.

Browser compatibility

Examples

This code just observes authentication requests for the target URL:

const target = "https://intranet.company.com/";

function observe(requestDetails) {
  console.log(`observing: ${requestDetails.requestId}`);
}

browser.webRequest.onAuthRequired.addListener(
  observe,
  {urls: [target]}
);

This code cancels authentication requests for the target URL:

const target = "https://intranet.company.com/";

function cancel(requestDetails) {
  console.log(`canceling: ${requestDetails.requestId}`);
  return {cancel: true};
}

browser.webRequest.onAuthRequired.addListener(
  cancel,
  {urls: [target]},
  ["blocking"]
);

This code supplies credentials synchronously. It has to keep track of outstanding requests, to ensure that it doesn't repeatedly try to submit bad credentials:

const target = "https://intranet.company.com/";

const myCredentials = {
  username: "[email protected]",
  password: "zDR$ERHGDFy"
}

const pendingRequests = [];

// A request has completed.
// We can stop worrying about it.
function completed(requestDetails) {
  console.log(`completed: ${requestDetails.requestId}`);
  var index = pendingRequests.indexOf(requestDetails.requestId);
  if (index > -1) {
    pendingRequests.splice(index, 1);
  }
}

function provideCredentialsSync(requestDetails) {
  // If we have seen this request before, then
  // assume our credentials were bad, and give up.
  if (pendingRequests.indexOf(requestDetails.requestId) != -1) {
    console.log(`bad credentials for: ${requestDetails.requestId}`);
    return {cancel:true};
  }
  pendingRequests.push(requestDetails.requestId);
  console.log(`providing credentials for: ${requestDetails.requestId}`);
  return {authCredentials: myCredentials};
}

browser.webRequest.onAuthRequired.addListener(
    provideCredentialsSync,
    {urls: [target]},
    ["blocking"]
  );

browser.webRequest.onCompleted.addListener(
  completed,
  {urls: [target]}
);

browser.webRequest.onErrorOccurred.addListener(
  completed,
  {urls: [target]}
);

This code supplies credentials asynchronously, fetching them from storage. It also has to keep track of outstanding requests, to ensure that it doesn't repeatedly try to submit bad credentials:

const target = "https://httpbin.org/basic-auth/*";

const pendingRequests = [];

/*
* A request has completed. We can stop worrying about it.
*/
function completed(requestDetails) {
  console.log(`completed: ${requestDetails.requestId}`);
  var index = pendingRequests.indexOf(requestDetails.requestId);
  if (index > -1) {
    pendingRequests.splice(index, 1);
  }
}

function provideCredentialsAsync(requestDetails) {
  // If we have seen this request before,
  // then assume our credentials were bad,
  // and give up.
  if (pendingRequests.indexOf(requestDetails.requestId) != -1) {
    console.log(`bad credentials for: ${requestDetails.requestId}`);
    return {cancel: true};

  } else {
    pendingRequests.push(requestDetails.requestId);
    console.log(`providing credentials for: ${requestDetails.requestId}`);
    // we can return a promise that will be resolved
    // with the stored credentials
    return browser.storage.local.get(null);
  }
}

browser.webRequest.onAuthRequired.addListener(
    provideCredentialsAsync,
    {urls: [target]},
    ["blocking"]
  );

browser.webRequest.onCompleted.addListener(
  completed,
  {urls: [target]}
);

browser.webRequest.onErrorOccurred.addListener(
  completed,
  {urls: [target]}
);

Example extensions

• stored-credentials