chrome/browser/ui/activity_services/canonical_url_retriever.h

// Copyright 2017 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef IOS_CHROME_BROWSER_UI_ACTIVITY_SERVICES_CANONICAL_URL_RETRIEVER_H_
#define IOS_CHROME_BROWSER_UI_ACTIVITY_SERVICES_CANONICAL_URL_RETRIEVER_H_

#import <Foundation/Foundation.h>

#import "ios/chrome/browser/procedural_block_types.h"

namespace web {
class WebState;
}

namespace activity_services {

// Retrieves the canonical URL in the web page represented by |web_state|.
// This method is asynchronous and the URL is returned by calling the
// |completion| block.
// There are a few special cases:
// 1. If there is more than one canonical URL defined, the first one
// (found through a depth-first search of the DOM) is given to |completion|.
// 2. If either no canonical URL is found, or the canonical URL is invalid, an
// empty GURL is given to |completion|.
// 3. If the canonical URL is a relative path, it is ignored and an empty GURL
// is given to |completion|.
// 4. If the the visible URL is not HTTPS, then an empty
// GURL is given to |completion|. This prevents untrusted sites from specifying
// the canonical URL.
// 5. If the canonical URL is not HTTPS, then an empty GURL is given to
// |completion|. This prevents the canonical URL from being downgraded to HTTP
// from the HTTPS visible URL.
void RetrieveCanonicalUrl(web::WebState* web_state,
                          ProceduralBlockWithURL completion);

}  // namespace activity_services

#endif  // IOS_CHROME_BROWSER_UI_ACTIVITY_SERVICES_CANONICAL_URL_RETRIEVER_H_