/*
* Copyright (c) 2022, Linus Groh <linusg@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <LibURL/URL.h>
#include <LibWeb/DOM/Document.h>
#include <LibWeb/DOMURL/DOMURL.h>
#include <LibWeb/Fetch/Infrastructure/HTTP/Requests.h>
#include <LibWeb/Fetch/Infrastructure/URL.h>
#include <LibWeb/HTML/Window.h>
#include <LibWeb/ReferrerPolicy/AbstractOperations.h>
#include <LibWeb/ReferrerPolicy/ReferrerPolicy.h>
#include <LibWeb/SecureContexts/AbstractOperations.h>
namespace Web::ReferrerPolicy {
// https://w3c.github.io/webappsec-referrer-policy/#determine-requests-referrer
Optional<URL::URL> determine_requests_referrer(Fetch::Infrastructure::Request const& request)
{
// 1. Let policy be request’s referrer policy.
auto const& policy = request.referrer_policy();
// 2. Let environment be request’s client.
auto environment = request.client();
// 3. Switch on request’s referrer:
auto referrer_source = request.referrer().visit(
// "client"
[&](Fetch::Infrastructure::Request::Referrer referrer) -> Optional<URL::URL> {
// Note: If request’s referrer is "no-referrer", Fetch will not call into this algorithm.
VERIFY(referrer == Fetch::Infrastructure::Request::Referrer::Client);
// FIXME: Add a const global_object() getter to ESO
auto& global_object = const_cast<HTML::EnvironmentSettingsObject&>(*environment).global_object();
// 1. If environment’s global object is a Window object, then
if (is<HTML::Window>(global_object)) {
// 1. Let document be the associated Document of environment’s global object.
auto const& document = static_cast<HTML::Window const&>(global_object).associated_document();
// 2. If document’s origin is an opaque origin, return no referrer.
if (document.origin().is_opaque())
return {};
// FIXME: 3. While document is an iframe srcdoc document, let document be document’s browsing context’s
// browsing context container’s node document.
// 4. Let referrerSource be document’s URL.
return document.url();
}
// 2. Otherwise, let referrerSource be environment’s creation URL.
else {
return environment->creation_url;
}
},
// a URL
[&](URL::URL const& url) -> Optional<URL::URL> {
// Let referrerSource be request’s referrer.
return url;
});
// NOTE: This only happens in step 1.2. of the "client" case above.
if (!referrer_source.has_value())
return {};
// 4. Let request’s referrerURL be the result of stripping referrerSource for use as a referrer.
auto referrer_url = strip_url_for_use_as_referrer(referrer_source);
// 5. Let referrerOrigin be the result of stripping referrerSource for use as a referrer, with the origin-only flag
// set to true.
auto referrer_origin = strip_url_for_use_as_referrer(referrer_source, OriginOnly::Yes);
// 6. If the result of serializing referrerURL is a string whose length is greater than 4096, set referrerURL to
// referrerOrigin.
if (referrer_url.has_value() && referrer_url.value().serialize().length() > 4096)
referrer_url = referrer_origin;
// 7. The user agent MAY alter referrerURL or referrerOrigin at this point to enforce arbitrary policy
// considerations in the interests of minimizing data leakage. For example, the user agent could strip the URL
// down to an origin, modify its host, replace it with an empty string, etc.
// 8. Execute the statements corresponding to the value of policy:
// Note: If request’s referrer policy is the empty string, Fetch will not call into this algorithm.
VERIFY(policy != ReferrerPolicy::EmptyString);
switch (policy) {
// "no-referrer"
case ReferrerPolicy::NoReferrer:
// Return no referrer
return {};
// "origin"
case ReferrerPolicy::Origin:
// Return referrerOrigin
return referrer_origin;
// "unsafe-url"
case ReferrerPolicy::UnsafeURL:
// Return referrerURL.
return referrer_url;
// "strict-origin"
case ReferrerPolicy::StrictOrigin:
// 1. If referrerURL is a potentially trustworthy URL and request’s current URL is not a potentially
// trustworthy URL, then return no referrer.
if (referrer_url.has_value()
&& SecureContexts::is_url_potentially_trustworthy(*referrer_url) == SecureContexts::Trustworthiness::PotentiallyTrustworthy
&& SecureContexts::is_url_potentially_trustworthy(request.current_url()) == SecureContexts::Trustworthiness::NotTrustworthy) {
return {};
}
// 2. Return referrerOrigin.
return referrer_origin;
// "strict-origin-when-cross-origin"
case ReferrerPolicy::StrictOriginWhenCrossOrigin:
// 1. If the origin of referrerURL and the origin of request’s current URL are the same, then return
// referrerURL.
if (referrer_url.has_value() && DOMURL::url_origin(*referrer_url).is_same_origin(DOMURL::url_origin(request.current_url())))
return referrer_url;
// 2. If referrerURL is a potentially trustworthy URL and request’s current URL is not a potentially
// trustworthy URL, then return no referrer.
if (referrer_url.has_value()
&& SecureContexts::is_url_potentially_trustworthy(*referrer_url) == SecureContexts::Trustworthiness::PotentiallyTrustworthy
&& SecureContexts::is_url_potentially_trustworthy(request.current_url()) == SecureContexts::Trustworthiness::NotTrustworthy) {
return {};
}
// 3. Return referrerOrigin.
return referrer_origin;
// "same-origin"
case ReferrerPolicy::SameOrigin:
// 1. If the origin of referrerURL and the origin of request’s current URL are the same, then return
// referrerURL.
if (referrer_url.has_value()
&& DOMURL::url_origin(*referrer_url).is_same_origin(DOMURL::url_origin(request.current_url()))) {
return referrer_url;
}
// 2. Return no referrer.
return {};
// "origin-when-cross-origin"
case ReferrerPolicy::OriginWhenCrossOrigin:
// 1. If the origin of referrerURL and the origin of request’s current URL are the same, then return
// referrerURL.
if (referrer_url.has_value()
&& DOMURL::url_origin(*referrer_url).is_same_origin(DOMURL::url_origin(request.current_url()))) {
return referrer_url;
}
// 2. Return referrerOrigin.
return referrer_origin;
// "no-referrer-when-downgrade"
case ReferrerPolicy::NoReferrerWhenDowngrade:
// 1. If referrerURL is a potentially trustworthy URL and request’s current URL is not a potentially
// trustworthy URL, then return no referrer.
if (referrer_url.has_value()
&& SecureContexts::is_url_potentially_trustworthy(*referrer_url) == SecureContexts::Trustworthiness::PotentiallyTrustworthy
&& SecureContexts::is_url_potentially_trustworthy(request.current_url()) == SecureContexts::Trustworthiness::NotTrustworthy) {
return {};
}
// 2. Return referrerURL.
return referrer_url;
default:
VERIFY_NOT_REACHED();
}
}
// https://w3c.github.io/webappsec-referrer-policy/#strip-url
Optional<URL::URL> strip_url_for_use_as_referrer(Optional<URL::URL> url, OriginOnly origin_only)
{
// 1. If url is null, return no referrer.
if (!url.has_value())
return {};
// 2. If url’s scheme is a local scheme, then return no referrer.
if (Fetch::Infrastructure::LOCAL_SCHEMES.span().contains_slow(url->scheme()))
return {};
// 3. Set url’s username to the empty string.
MUST(url->set_username(""sv));
// 4. Set url’s password to the empty string.
MUST(url->set_password(""sv));
// 5. Set url’s fragment to null.
url->set_fragment({});
// 6. If the origin-only flag is true, then:
if (origin_only == OriginOnly::Yes) {
// 1. Set url’s path to « the empty string ».
url->set_paths({ ""sv });
// 2. Set url’s query to null.
url->set_query({});
}
// 7. Return url.
return url;
}
}