webRequest.onAuthRequired

In Firefox and Chrome Manifest V2 extensions, you must add the "webRequest" and "webRequestBlocking" API permissions to your manifest.json.

For Manifest V3 extensions, Chrome no longer supports the "webRequestBlocking" permission (except for policy-installed extensions). Instead, the "webRequest" and "webRequestAuthProvider" permissions enable you to supply credentials asynchronously. Firefox continues to support "webRequestBlocking" in Manifest V3 and provides "webRequestAuthProvider" to offer cross-browser compatibility.

Firefox does not generally 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 supports an exception to this.

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

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(listener, 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.

listener

The function called when this event occurs. The function is passed these arguments:

details

object. Details about the request. See the details section for more information.

asyncCallback Optional

A function to call, at most once, to asynchronously modify the request object. This parameter is only present if the event listener is registered with "asyncBlocking" in the extraInfoSpec array. asyncCallback is undefined if extraInfoSpec is not provided or contains "blocking".

Returns: webRequest.BlockingResponse or a Promise depending on the settings in extraInfoSpec.

filter

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

extraInfoSpec Optional

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

• "blocking": make the request block so you can cancel the request or supply authentication credentials. Return a BlockingResponse object with its cancel or authCredentials properties set.

  • In Chrome, the event listener must respond synchronously.
  • In Firefox, the event listener can respond synchronously or return a promise that resolves to a BlockingResponse object to respond asynchronously.

• "asyncBlocking": handle the request asynchronously. The return value of the event listener is ignored. To resolve the event, pass the asyncCallback parameter a BlockingResponse object.

  • Supported from Chrome 120 and Firefox 128.
  • Not supported in Safari.

challenger

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

host

string. The server's hostname.

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. See Work with contextual identities for more information.

frameId

integer. This is 0 if the request occurs in the main frame; a positive value is the ID of a subframe where the request happens. If the document of a (sub-)frame is loaded (type is main_frame or sub_frame), frameId indicates this frame's ID, not the outer frame's ID. 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/TLS proxy servers requiring authentication, 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 that 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 performs 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() is used.

realm Optional

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 relate different events associated with the same request.

responseHeaders Optional

webRequest.HttpHeaders. The HTTP response headers received 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, 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 where 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", or "stylesheet".

url

string. Target of the request.

urlClassification

object. The type of tracking associated with the request, if the request is classified by Firefox Tracking Protection. This is an object with these 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 ("an origin found to fingerprint").
  • fingerprinting indicates the domain is in the fingerprinting and tracking category. Examples of this type of domain include advertisers who want to associate a profile with the visiting user.
  • fingerprinting_content indicates the domain is in the fingerprinting category but not the tracking category. Examples of this type of domain include payment providers who use fingerprinting techniques to identify the visiting user for anti-fraud purposes.
• 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.
• emailtracking and emailtracking_content: indicates the request is involved in tracking emails.
• any_basic_tracking: a meta flag that combines tracking and fingerprinting flags, excluding tracking_content and fingerprinting_content.
• any_strict_tracking: a meta flag that combines all tracking and fingerprinting flags.
• any_social_tracking: a meta flag that combines all social tracking flags.

You can find more information on tracker types on the disconnect.me website. The content suffix indicates trackers that track and serve content. Blocking them protects users but can lead to sites breaking or elements not being displayed.

This code 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 keeps 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: "me@company.com",
  password: "zDR$ERHGDFy",
};

const pendingRequests = [];

// A request has completed.
// We can stop worrying about it.
function completed(requestDetails) {
  console.log(`completed: ${requestDetails.requestId}`);
  let 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.includes(requestDetails.requestId)) {
    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 keeps 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}`);
  let 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.includes(requestDetails.requestId)) {
    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] });

• stored-credentials