// Copyright (c) 2012 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 CONTENT_BROWSER_SITE_INSTANCE_IMPL_H_
#define CONTENT_BROWSER_SITE_INSTANCE_IMPL_H_

#include <stddef.h>
#include <stdint.h>

#include "base/observer_list.h"
#include "base/optional.h"
#include "content/browser/isolation_context.h"
#include "content/browser/renderer_host/render_process_host_impl.h"
#include "content/common/content_export.h"
#include "content/public/browser/render_process_host_observer.h"
#include "content/public/browser/site_instance.h"
#include "url/gurl.h"
#include "url/origin.h"

namespace content {
class BrowsingInstance;
class RenderProcessHostFactory;

// SiteInfo represents the principal of a SiteInstance. All documents and
// workers within a SiteInstance are considered part of this principal and will
// share a renderer process. Any two documents within the same browsing context
// group (i.e., BrowsingInstance) that are allowed to script each other *must*
// have the same SiteInfo principal, so that they end up in the same renderer
// process.
//
// As a result, SiteInfo is primarily defined in terms of "site URL," which is
// often the scheme plus the eTLD+1 of a URL. This allows same-site URLs to
// always share a process even when document.domain is modified. However, some
// site URLs can be finer grained (e.g., origins) or coarser grained (e.g.,
// file://). See |site_url()| for more considerations.
//
// In the future, we may add more information to SiteInfo for cases where the
// site URL is not sufficient to identify which process a document belongs in.
// For example, origin isolation (https://crbug.com/1067389) will introduce a
// 'keying' bit ('site' or 'origin') to avoid an ambiguity between sites and
// origins, and it will be possible for two SiteInstances with different keying
// values to have the same site URL. It is important that any extra members of
// SiteInfo do not cause two documents that can script each other to end up in
// different SiteInfos and thus different processes.
//
// TODO(wjmaclean): This should eventually move to
// content/public/browser/site_info.h.
class CONTENT_EXPORT SiteInfo {
 public:
  static SiteInfo CreateForErrorPage();

  explicit SiteInfo(const GURL& site_url);
  SiteInfo() = default;

  // Returns the site URL associated with all of the documents and workers in
  // this principal, as described above.
  //
  // NOTE: In most cases, code should be performing checks against the origin
  // returned by |RenderFrameHost::GetLastCommittedOrigin()|. In contrast, the
  // GURL returned by |site_url()| should not be considered authoritative
  // because:
  // - A SiteInstance can host pages from multiple sites if "site per process"
  //   is not enabled and the SiteInstance isn't hosting pages that require
  //   process isolation (e.g. WebUI or extensions).
  // - Even with site per process, the site URL is not an origin: while often
  //   derived from the origin, it only contains the scheme and the eTLD + 1,
  //   i.e. an origin with the host "deeply.nested.subdomain.example.com"
  //   corresponds to a site URL with the host "example.com".
  // - When origin isolation is in use, there may be multiple SiteInstance with
  //   the same site_url() but that differ in other properties.
  const GURL& site_url() const { return site_url_; }

  bool operator==(const SiteInfo& other) const;
  bool operator!=(const SiteInfo& other) const;

  // Returns a string representation of this SiteInfo principal.
  std::string GetDebugString() const;

 private:
  GURL site_url_;
  // TODO(crbug.com/1067389): Add site vs origin granularity.
};

std::ostream& operator<<(std::ostream& out, const SiteInfo& site_info);

class CONTENT_EXPORT SiteInstanceImpl final : public SiteInstance,
                                              public RenderProcessHostObserver {
 public:
  class CONTENT_EXPORT Observer {
   public:
    // Called when this SiteInstance transitions to having no active frames,
    // as measured by active_frame_count().
    virtual void ActiveFrameCountIsZero(SiteInstanceImpl* site_instance) {}

    // Called when the renderer process of this SiteInstance has exited.
    virtual void RenderProcessGone(SiteInstanceImpl* site_instance,
                                   const ChildProcessTerminationInfo& info) = 0;
  };

  // Methods for creating new SiteInstances. The documentation for these methods
  // are on the SiteInstance::Create* methods with the same name.
  static scoped_refptr<SiteInstanceImpl> Create(
      BrowserContext* browser_context);
  static scoped_refptr<SiteInstanceImpl> CreateForURL(
      BrowserContext* browser_context,
      const GURL& url);
  static scoped_refptr<SiteInstanceImpl> CreateForGuest(
      content::BrowserContext* browser_context,
      const GURL& guest_site_url);

  // Creates a SiteInstance that will be use for a service worker.
  // |url| - The script URL for the service worker if |is_guest| is false.
  //         The <webview> guest site URL if |is_guest| is true.
  // |can_reuse_process| - Set to true if the new SiteInstance can use the
  //                       same process as the renderer for |url|.
  // |is_guest| - Set to true if the new SiteInstance is for a <webview>
  // guest.
  static scoped_refptr<SiteInstanceImpl> CreateForServiceWorker(
      BrowserContext* browser_context,
      const GURL& url,
      bool can_reuse_process = false,
      bool is_guest = false);

  // Creates a SiteInstance for |url| like CreateForURL() would except the
  // instance that is returned has its process_reuse_policy set to
  // REUSE_PENDING_OR_COMMITTED_SITE and the default SiteInstance will never
  // be returned.
  static scoped_refptr<SiteInstanceImpl> CreateReusableInstanceForTesting(
      BrowserContext* browser_context,
      const GURL& url);

  static bool ShouldAssignSiteForURL(const GURL& url);

  // Returns whether |lock_url| is at least at the granularity of a site (i.e.,
  // a scheme plus eTLD+1, like https://google.com).  Also returns true if the
  // lock is to a more specific origin (e.g., https://accounts.google.com), but
  // not if the lock is empty or applies to an entire scheme (e.g., file://).
  static bool IsOriginLockASite(const GURL& lock_url);

  // Return whether both URLs are part of the same web site, for the purpose of
  // assigning them to processes accordingly.  The decision is currently based
  // on the registered domain of the URLs (google.com, bbc.co.uk), as well as
  // the scheme (https, http).  Note that if the destination is a blank page,
  // we consider that to be part of the same web site for the purposes for
  // process assignment.  |should_compare_effective_urls| allows comparing URLs
  // without converting them to effective URLs first.  This is useful for
  // avoiding OOPIFs when otherwise same-site URLs may look cross-site via
  // their effective URLs.
  static bool IsSameSite(const IsolationContext& isolation_context,
                         const GURL& src_url,
                         const GURL& dest_url,
                         bool should_compare_effective_urls);

  // SiteInstance interface overrides.
  int32_t GetId() override;
  int32_t GetBrowsingInstanceId() override;
  bool HasProcess() override;
  RenderProcessHost* GetProcess() override;
  BrowserContext* GetBrowserContext() override;
  const GURL& GetSiteURL() override;
  scoped_refptr<SiteInstance> GetRelatedSiteInstance(const GURL& url) override;
  bool IsRelatedSiteInstance(const SiteInstance* instance) override;
  size_t GetRelatedActiveContentsCount() override;
  bool RequiresDedicatedProcess() override;
  bool IsSameSiteWithURL(const GURL& url) override;
  bool IsGuest() override;

  // The policy to apply when selecting a RenderProcessHost for the
  // SiteInstance. If no suitable RenderProcessHost for the SiteInstance exists
  // according to the policy, and there are processes with unmatched service
  // workers for the site, the newest process with an unmatched service worker
  // is reused. If still no RenderProcessHost exists a new RenderProcessHost
  // will be created unless the process limit has been reached. When the limit
  // has been reached, the RenderProcessHost reused will be chosen randomly and
  // not based on the site.
  enum class ProcessReusePolicy {
    // In this mode, all instances of the site will be hosted in the same
    // RenderProcessHost.
    PROCESS_PER_SITE,

    // In this mode, the site will be rendered in a RenderProcessHost that is
    // already in use for the site, either for a pending navigation or a
    // committed navigation. If multiple such processes exist, ones that have
    // foreground frames are given priority, and otherwise one is selected
    // randomly.
    REUSE_PENDING_OR_COMMITTED_SITE,

    // In this mode, SiteInstances don't proactively reuse processes. An
    // existing process with an unmatched service worker for the site is reused
    // only for navigations, not for service workers. When the process limit has
    // been reached, a randomly chosen RenderProcessHost is reused as in the
    // other policies.
    DEFAULT,
  };

  void set_process_reuse_policy(ProcessReusePolicy policy) {
    DCHECK(!IsDefaultSiteInstance());
    process_reuse_policy_ = policy;
  }
  ProcessReusePolicy process_reuse_policy() const {
    return process_reuse_policy_;
  }

  // Checks if |current_process| can be reused for this SiteInstance, and
  // sets |process_| to |current_process| if so.
  void ReuseCurrentProcessIfPossible(RenderProcessHost* current_process);

  // Whether the SiteInstance is created for a service worker. If this flag
  // is true, when a new process is created for this SiteInstance or a randomly
  // chosen existing process is reused because of the process limit, the process
  // will be tracked as having an unmatched service worker until reused by
  // another SiteInstance from the same site.
  bool is_for_service_worker() const { return is_for_service_worker_; }

  // Returns the URL which was used to set the |site_| for this SiteInstance.
  // May be empty if this SiteInstance does not have a |site_|.
  const GURL& original_url() {
    DCHECK(!IsDefaultSiteInstance());
    return original_url_;
  }

  // Returns true if |original_url()| is the same site as
  // |dest_url| or this object is a default SiteInstance and can be
  // considered the same site as |dest_url|.
  bool IsOriginalUrlSameSite(const GURL& dest_url,
                             bool should_compare_effective_urls);

  // Returns the URL which should be used in a LockToOrigin call for this
  // SiteInstance's process.  This is the same as |site_| except for cases
  // involving effective URLs, such as hosted apps.  In those cases, this URL
  // is a site URL that is computed without the use of effective URLs.
  //
  // NOTE: This URL is currently set even in cases where this SiteInstance's
  // process is *not* going to be locked to it.  Callers should be careful to
  // consider this case when comparing lock URLs; ShouldLockToOrigin() may be
  // used to determine whether the process lock will actually be used.
  //
  // TODO(alexmos): See if we can clean this up and not set |lock_url_| if the
  // SiteInstance's process isn't going to be locked.
  const GURL& lock_url() { return lock_url_; }

  // True if |url| resolves to an effective URL that is different from |url|.
  // See GetEffectiveURL().  This will be true for hosted apps as well as NTP
  // URLs.
  static bool HasEffectiveURL(BrowserContext* browser_context, const GURL& url);

  // SiteInfo related functions.

  // Returns the SiteInfo principal identifying all documents and workers within
  // this SiteInstance.
  // TODO(wjmaclean): eventually this function will replace const GURL&
  // GetSiteURL().
  const SiteInfo& GetSiteInfo();

  // Note: eventually this function will replace GetSiteForURL().
  static SiteInfo ComputeSiteInfo(const IsolationContext& isolation_context,
                                  const GURL& url);

  // Returns the site for the given URL, which includes only the scheme and
  // registered domain.  Returns an empty GURL if the URL has no host.
  // |url| will be resolved to an effective URL (via
  // ContentBrowserClient::GetEffectiveURL()) before determining the site.
  // NOTE: This function will soon be removed, and replaced by
  // ComputeSiteInfo(). New code should use that function instead.
  static GURL GetSiteForURL(const IsolationContext& isolation_context,
                            const GURL& url);

  // Returns the site of a given |origin|.  Unlike GetSiteForURL(), this does
  // not utilize effective URLs, isolated origins, or other special logic.  It
  // only translates an origin into a site (i.e., scheme and eTLD+1) and is
  // used internally by GetSiteForURL().  For making process model decisions,
  // GetSiteForURL() should be used instead.
  static GURL GetSiteForOrigin(const url::Origin& origin);

  // Returns the URL to which a process should be locked for the given URL.
  // This is computed similarly to the site URL (see GetSiteForURL), but
  // without resolving effective URLs.
  static GURL DetermineProcessLockURL(const IsolationContext& isolation_context,
                                      const GURL& url);

  // Set the web site that this SiteInstance is rendering pages for.
  // This includes the scheme and registered domain, but not the port.  If the
  // URL does not have a valid registered domain, then the full hostname is
  // stored. This method does not convert this instance into a default
  // SiteInstance, but the BrowsingInstance will call this method with |url|
  // set to GetDefaultSiteURL(), when it is creating its default SiteInstance.
  void SetSite(const GURL& url);

  // Similar to SetSite(), but first attempts to convert this object to a
  // default SiteInstance if |url| can be placed inside a default SiteInstance.
  // If conversion is not possible, then the normal SetSite() logic is run.
  void ConvertToDefaultOrSetSite(const GURL& url);

  // Returns whether SetSite() has been called.
  bool HasSite() const;

  // Returns whether there is currently a related SiteInstance (registered with
  // BrowsingInstance) for the site of the given url.  If so, we should try to
  // avoid dedicating an unused SiteInstance to it (e.g., in a new tab).
  bool HasRelatedSiteInstance(const GURL& url);

  // Returns whether this SiteInstance is compatible with and can host the given
  // |url|. If not, the browser should force a SiteInstance swap when
  // navigating to |url|.
  bool IsSuitableForURL(const GURL& url);

  // Increase the number of active frames in this SiteInstance. This is
  // increased when a frame is created.
  void IncrementActiveFrameCount();

  // Decrease the number of active frames in this SiteInstance. This is
  // decreased when a frame is destroyed. Decrementing this to zero will notify
  // observers, and may trigger deletion of proxies.
  void DecrementActiveFrameCount();

  // Get the number of active frames which belong to this SiteInstance.  If
  // there are no active frames left, all frames in this SiteInstance can be
  // safely discarded.
  size_t active_frame_count() { return active_frame_count_; }

  // Increase the number of active WebContentses using this SiteInstance. Note
  // that, unlike active_frame_count, this does not count pending RFHs.
  void IncrementRelatedActiveContentsCount();

  // Decrease the number of active WebContentses using this SiteInstance. Note
  // that, unlike active_frame_count, this does not count pending RFHs.
  void DecrementRelatedActiveContentsCount();

  void AddObserver(Observer* observer);
  void RemoveObserver(Observer* observer);

  // Whether GetProcess() method (when it needs to find a new process to
  // associate with the current SiteInstanceImpl) can return a spare process.
  bool CanAssociateWithSpareProcess();

  // Has no effect if the SiteInstanceImpl already has a |process_|.
  // Otherwise, prevents GetProcess() from associating this SiteInstanceImpl
  // with the spare RenderProcessHost - instead GetProcess will either need to
  // create a new, not-yet-initialized/spawned RenderProcessHost or will need to
  // reuse one of existing RenderProcessHosts.
  //
  // See also:
  // - https://crbug.com/840409.
  // - WebContents::CreateParams::desired_renderer_state
  // - SiteInstanceImpl::CanAssociateWithSpareProcess().
  void PreventAssociationWithSpareProcess();

  // Returns the special site URL used by the default SiteInstance.
  static const GURL& GetDefaultSiteURL();

  // Get the effective URL for the given actual URL.  This allows the
  // ContentBrowserClient to override the SiteInstance's site for certain URLs.
  // For example, Chrome uses this to replace hosted app URLs with extension
  // hosts.
  // Only public so that we can make a consistent process swap decision in
  // RenderFrameHostManager.
  static GURL GetEffectiveURL(BrowserContext* browser_context,
                              const GURL& url);

  // Returns true if pages loaded from |url| ought to be handled only by a
  // renderer process isolated from other sites. If --site-per-process is used,
  // this is true for all sites. In other site isolation modes, only a subset
  // of sites will require dedicated processes.
  static bool DoesSiteRequireDedicatedProcess(
      const IsolationContext& isolation_context,
      const GURL& url);

  // Returns true if a process for a site |site_url| should be locked to just
  // that site. Returning true here also implies that |site_url| requires a
  // dedicated process. However, the converse does not hold: this might still
  // return false for certain special cases where an origin lock can't be
  // applied even when |site_url| requires a dedicated process (e.g., with
  // --site-per-process). Examples of those cases include <webview> guests,
  // single-process mode, or extensions where a process is currently allowed to
  // be reused for different extensions.  Most of these special cases should
  // eventually be removed, and this function should become equivalent to
  // DoesSiteRequireDedicatedProcess().
  //
  // Note that this function currently requires passing in a site URL (which
  // may use effective URLs), and not a lock URL to which the process may
  // eventually be locked via LockToOrigin().  See comments on lock_url() for
  // more info. |is_guest| should be set to true if the call is being made for
  // a <webview> guest SiteInstance(i.e. SiteInstance::IsGuest() returns true).
  // TODO(alexmos):  See if this can take a lock URL instead.
  static bool ShouldLockToOrigin(const IsolationContext& isolation_context,
                                 const GURL& site_url,
                                 const bool is_guest);

  // Converts |lock_url| into an origin that can be used as
  // |URLLoaderFactoryParams::request_initiator_site_lock|.
  // This means that the returned origin can be safely used in a eTLD+1
  // comparison against |network::ResourceRequest::request_initiator|.
  //
  // base::nullopt is returned if |lock_url| cannot be used as a
  // |request_initiator_site_lock| (e.g. in case of site_url =
  // chrome-guest://...).
  static base::Optional<url::Origin> GetRequestInitiatorSiteLock(GURL lock_url);

  // Return an ID of the next BrowsingInstance to be created.  This ID is
  // guaranteed to be higher than any ID of an existing BrowsingInstance.
  // This is useful when process model decisions need to be scoped only to
  // future BrowsingInstances.  In particular, this can determine the cutoff in
  // BrowsingInstance IDs when adding a new isolated origin dynamically.
  static BrowsingInstanceId NextBrowsingInstanceId();

  // Return the IsolationContext associated with this SiteInstance.  This
  // specifies context for making process model decisions, such as information
  // about the current BrowsingInstance.
  const IsolationContext& GetIsolationContext();

  // If this SiteInstance doesn't require a dedicated process, this will return
  // the BrowsingInstance's default process.
  RenderProcessHost* GetDefaultProcessIfUsable();

  // Returns true if this object was constructed as a default site instance.
  bool IsDefaultSiteInstance() const;

  // Returns true if |site_url| is a site URL that the BrowsingInstance has
  // associated with its default SiteInstance.
  bool IsSiteInDefaultSiteInstance(const GURL& site_url) const;

  // Returns true if the the site URL for |url| matches the site URL
  // for this instance (i.e. GetSiteURL()). Otherwise returns false.
  bool DoesSiteForURLMatch(const GURL& url);

  // Adds |origin| as a non-isolated origin within this BrowsingInstance due to
  // an existing instance at the time of opt-in, so that future instances of it
  // here won't be origin isolated.
  void PreventOptInOriginIsolation(
      const url::Origin& previously_visited_origin);

 private:
  friend class BrowsingInstance;
  friend class SiteInstanceTestBrowserClient;
  FRIEND_TEST_ALL_PREFIXES(SiteInstanceTest, ProcessLockDoesNotUseEffectiveURL);

  // Create a new SiteInstance.  Only BrowsingInstance should call this
  // directly; clients should use Create() or GetRelatedSiteInstance() instead.
  explicit SiteInstanceImpl(BrowsingInstance* browsing_instance);

  ~SiteInstanceImpl() override;

  // RenderProcessHostObserver implementation.
  void RenderProcessHostDestroyed(RenderProcessHost* host) override;
  void RenderProcessExited(RenderProcessHost* host,
                           const ChildProcessTerminationInfo& info) override;

  // Used to restrict a process' origin access rights.
  void LockToOriginIfNeeded();

  // If kProcessSharingWithStrictSiteInstances is enabled, this will check
  // whether both a site and a process have been assigned to this SiteInstance,
  // and if this doesn't require a dedicated process, will offer process_ to
  // BrowsingInstance as the default process for SiteInstances that don't need
  // a dedicated process.
  void MaybeSetBrowsingInstanceDefaultProcess();

  // Sets |site_| and |lock_| with |site_url| and |lock_url| respectively
  // and registers this object with |browsing_instance_|. SetSite() calls
  // this method to set the site and lock for a user provided URL. This
  // method should only be called by code that need to set the site and
  // lock directly without any "url to site URL" transformation.
  void SetSiteAndLockInternal(const GURL& site_url, const GURL& lock_url);

  // Helper method to set the process of this SiteInstance, only in cases
  // where it is safe. It is not generally safe to change the process of a
  // SiteInstance, unless the RenderProcessHost itself is entirely destroyed and
  // a new one later replaces it.
  void SetProcessInternal(RenderProcessHost* process);

  // Returns the site for the given URL, which includes only the scheme and
  // registered domain.  Returns an empty GURL if the URL has no host.
  // |should_use_effective_urls| specifies whether to resolve |url| to an
  // effective URL (via ContentBrowserClient::GetEffectiveURL()) before
  // determining the site.
  // |allow_default_site_url| specifies whether the default SiteInstance site
  // URL is allowed to be returned.
  static GURL GetSiteForURLInternal(const IsolationContext& isolation_context,
                                    const GURL& url,
                                    bool should_use_effective_urls,
                                    bool allow_default_site_url);

  // Returns true if pages loaded from |site_url| ought to be handled only by a
  // renderer process isolated from other sites. If --site-per-process is used,
  // this is true for all sites. In other site isolation modes, only a subset
  // of sites will require dedicated processes.
  // Note: Unlike DoesSiteRequireDedicatedProcess(), this method expects a site
  // URL instead of a plain URL.
  static bool DoesSiteURLRequireDedicatedProcess(
      const IsolationContext& isolation_context,
      const GURL& site_url);

  // Returns true if |url| and its |site_url| can be placed inside a default
  // SiteInstance.
  //
  // Note: |url| and |site_url| must be consistent with each other. In contexts
  // where the caller only has |url| it can use
  // SiteInstanceImpl::GetSiteForURL() to generate |site_url|. This call is
  // intentionally not set as a default value to encourage the caller to reuse
  // a site URL computation if they already have one.
  static bool CanBePlacedInDefaultSiteInstance(
      const IsolationContext& isolation_context,
      const GURL& url,
      const GURL& site_url);

  // An object used to construct RenderProcessHosts.
  static const RenderProcessHostFactory* g_render_process_host_factory_;

  // The next available SiteInstance ID.
  static int32_t next_site_instance_id_;

  // A unique ID for this SiteInstance.
  int32_t id_;

  // The number of active frames in this SiteInstance.
  size_t active_frame_count_;

  // BrowsingInstance to which this SiteInstance belongs.
  scoped_refptr<BrowsingInstance> browsing_instance_;

  // Current RenderProcessHost that is rendering pages for this SiteInstance.
  // This pointer will only change once the RenderProcessHost is destructed.  It
  // will still remain the same even if the process crashes, since in that
  // scenario the RenderProcessHost remains the same.
  RenderProcessHost* process_;

  // Describes the desired behavior when GetProcess() method needs to find a new
  // process to associate with the current SiteInstanceImpl.  If |false|, then
  // prevents the spare RenderProcessHost from being taken and stored in
  // |process_|.
  bool can_associate_with_spare_process_;

  // The web site that this SiteInstance is rendering pages for.
  SiteInfo site_;

  // Whether SetSite has been called.
  bool has_site_;

  // The URL which was used to set the |site_| for this SiteInstance.
  GURL original_url_;

  // The URL to use when locking a process to this SiteInstance's site via
  // LockToOrigin().  This is the same as |site_| except for cases involving
  // effective URLs, such as hosted apps.  In those cases, this URL is a site
  // URL that is computed without the use of effective URLs.
  GURL lock_url_;

  // The ProcessReusePolicy to use when creating a RenderProcessHost for this
  // SiteInstance.
  ProcessReusePolicy process_reuse_policy_;

  // Whether the SiteInstance was created for a service worker.
  bool is_for_service_worker_;

  // Whether the SiteInstance was created for a <webview> guest.
  // TODO(734722): Move this into the SecurityPrincipal once it is available.
  bool is_guest_;

  base::ObserverList<Observer, true>::Unchecked observers_;

  DISALLOW_COPY_AND_ASSIGN(SiteInstanceImpl);
};

}  // namespace content

#endif  // CONTENT_BROWSER_SITE_INSTANCE_IMPL_H_