/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/*
 * Utility routines for checking content load/process policy settings,
 * and routines helpful for content policy implementors.
 *
 * XXXbz it would be nice if some of this stuff could be out-of-lined in
 * nsContentUtils.  That would work for almost all the callers...
 */

#ifndef _nsContentPolicyUtils_h_
#define _nsContentPolicyUtils_h_

#include "mozilla/BasePrincipal.h"
#include "mozilla/dom/nsCSPService.h"
#include "nsContentPolicyType.h"
#include "nsContentUtils.h"
#include "nsIContent.h"
#include "nsIContentPolicy.h"
#include "nsIURI.h"
#include "nsPIDOMWindow.h"
#include "nsPIDOMWindowInlines.h"  // FIXME: Stop including inline definitions!
#include "nsServiceManagerUtils.h"
#include "nsStringFwd.h"

// XXXtw sadly, this makes consumers of nsContentPolicyUtils depend on widget
#include "mozilla/dom/Document.h"

#define NS_CONTENTPOLICY_CONTRACTID "@mozilla.org/layout/content-policy;1"
#define NS_CONTENTPOLICY_CATEGORY "content-policy"
#define NS_CONTENTPOLICY_CID \
  {0x0e3afd3d, 0xeb60, 0x4c2b, {0x96, 0x3b, 0x56, 0xd7, 0xc4, 0x39, 0xf1, 0x24}}

/**
 * Evaluates to true if val is ACCEPT.
 *
 * @param val the status returned from shouldProcess/shouldLoad
 */
#define NS_CP_ACCEPTED(val) ((val) == nsIContentPolicy::ACCEPT)

/**
 * Evaluates to true if val is a REJECT_* status
 *
 * @param val the status returned from shouldProcess/shouldLoad
 */
#define NS_CP_REJECTED(val) ((val) != nsIContentPolicy::ACCEPT)

// Offer convenient translations of constants -> const char*

// convenience macro to reduce some repetative typing...
// name is the name of a constant from this interface
#define CASE_RETURN(name)      \
  case nsIContentPolicy::name: \
    return #name

/**
 * Returns a string corresponding to the name of the response constant, or
 * "<Unknown Response>" if an unknown response value is given.
 *
 * The return value is static and must not be freed.
 *
 * @param response the response code
 * @return the name of the given response code
 */
inline const char* NS_CP_ResponseName(int16_t response) {
  switch (response) {
    CASE_RETURN(REJECT_REQUEST);
    CASE_RETURN(REJECT_TYPE);
    CASE_RETURN(REJECT_SERVER);
    CASE_RETURN(REJECT_OTHER);
    CASE_RETURN(ACCEPT);
    default:
      return "<Unknown Response>";
  }
}

/**
 * Returns a string corresponding to the name of the content type constant, or
 * "<Unknown Type>" if an unknown content type value is given.
 *
 * The return value is static and must not be freed.
 *
 * @param contentType the content type code
 * @return the name of the given content type code
 */
inline const char* NS_CP_ContentTypeName(nsContentPolicyType contentType) {
  switch (contentType) {
#define TYPE_TO_STRING(name)      \
  case nsContentPolicyType::name: \
    return #name;
    FOR_EACH_CONTENT_POLICY_TYPE(TYPE_TO_STRING)
#undef TYPE_TO_STRING

    case nsContentPolicyType::TYPE_INVALID:
      break;

      // Do not add default: so that compilers can catch the missing case.
  }
  return "<Unknown Type>";
}

#undef CASE_RETURN

inline const char* NS_CP_ContentTypeName(ExtContentPolicyType contentType) {
  return NS_CP_ContentTypeName(static_cast<nsContentPolicyType>(contentType));
}

/* Passes on parameters from its "caller"'s context. */
#define CHECK_CONTENT_POLICY(action)                          \
  PR_BEGIN_MACRO                                              \
  nsCOMPtr<nsIContentPolicy> policy =                         \
      do_GetService(NS_CONTENTPOLICY_CONTRACTID);             \
  if (!policy) return NS_ERROR_FAILURE;                       \
                                                              \
  return policy->action(contentLocation, loadInfo, decision); \
  PR_END_MACRO

/* Passes on parameters from its "caller"'s context. */
#define CHECK_CONTENT_POLICY_WITH_SERVICE(action, _policy)     \
  PR_BEGIN_MACRO                                               \
  return _policy->action(contentLocation, loadInfo, decision); \
  PR_END_MACRO

/**
 * Check whether we can short-circuit this check and bail out.  If not, get the
 * origin URI to use.
 *
 * Note: requestOrigin is scoped outside the PR_BEGIN_MACRO/PR_END_MACRO on
 * purpose */
#define CHECK_PRINCIPAL_CSP_AND_DATA(action)                                  \
  PR_BEGIN_MACRO                                                              \
  if (loadingPrincipal && loadingPrincipal->IsSystemPrincipal()) {            \
    /* We exempt most loads into any document with the system principal       \
     * from content policy (except CSP) checks, mostly as an optimization.    \
     * Which means that we need to apply this check to the loading principal, \
     * not the principal that triggered the load. */                          \
    /* Check CSP for System Privileged pages */                               \
    CSPService::ConsultCSP(contentLocation, loadInfo, decision);              \
    if (NS_CP_REJECTED(*decision)) {                                          \
      return NS_OK;                                                           \
    }                                                                         \
    if (contentType != nsIContentPolicy::TYPE_DOCUMENT &&                     \
        contentType != nsIContentPolicy::TYPE_UA_FONT) {                      \
      *decision = nsIContentPolicy::ACCEPT;                                   \
      nsCOMPtr<nsINode> n = do_QueryInterface(context);                       \
      if (!n) {                                                               \
        nsCOMPtr<nsPIDOMWindowOuter> win = do_QueryInterface(context);        \
        n = win ? win->GetExtantDoc() : nullptr;                              \
      }                                                                       \
      if (n) {                                                                \
        mozilla::dom::Document* d = n->OwnerDoc();                            \
        if (d->IsLoadedAsData() || d->IsBeingUsedAsImage() ||                 \
            d->IsResourceDoc()) {                                             \
          nsCOMPtr<nsIContentPolicy> dataPolicy =                             \
              do_GetService("@mozilla.org/data-document-content-policy;1");   \
          if (dataPolicy) {                                                   \
            dataPolicy->action(contentLocation, loadInfo, decision);          \
          }                                                                   \
        }                                                                     \
      }                                                                       \
    }                                                                         \
    return NS_OK;                                                             \
  }                                                                           \
  PR_END_MACRO

/**
 * Alias for calling ShouldLoad on the content policy service.  Parameters are
 * the same as nsIContentPolicy::shouldLoad, except for the loadingPrincipal
 * and triggeringPrincipal parameters (which should be non-null if possible,
 * and have the same semantics as in nsLoadInfo), and the last parameter,
 * which can be used to pass in a pointer to a useful service if the caller
 * already has it.  The origin URI to pass to shouldLoad will be the URI of
 * loadingPrincipal, unless loadingPrincipal is null (in which case a null
 * origin URI will be passed).
 */
inline nsresult NS_CheckContentLoadPolicy(
    nsIURI* contentLocation, nsILoadInfo* loadInfo, int16_t* decision,
    nsIContentPolicy* policyService = nullptr) {
  nsIPrincipal* loadingPrincipal = loadInfo->GetLoadingPrincipal();
  nsCOMPtr<nsISupports> context = loadInfo->GetLoadingContext();
  nsContentPolicyType contentType = loadInfo->InternalContentPolicyType();
  CHECK_PRINCIPAL_CSP_AND_DATA(ShouldLoad);
  if (policyService) {
    CHECK_CONTENT_POLICY_WITH_SERVICE(ShouldLoad, policyService);
  }
  CHECK_CONTENT_POLICY(ShouldLoad);
}

/**
 * Alias for calling ShouldProcess on the content policy service.
 */
inline nsresult NS_CheckContentProcessPolicy(
    nsIURI* contentLocation, nsILoadInfo* loadInfo, int16_t* decision,
    nsIContentPolicy* policyService = nullptr) {
  nsIPrincipal* loadingPrincipal = loadInfo->GetLoadingPrincipal();
  nsCOMPtr<nsISupports> context = loadInfo->GetLoadingContext();
  nsContentPolicyType contentType = loadInfo->InternalContentPolicyType();
  CHECK_PRINCIPAL_CSP_AND_DATA(ShouldProcess);
  if (policyService) {
    CHECK_CONTENT_POLICY_WITH_SERVICE(ShouldProcess, policyService);
  }
  CHECK_CONTENT_POLICY(ShouldProcess);
}

#undef CHECK_CONTENT_POLICY
#undef CHECK_CONTENT_POLICY_WITH_SERVICE

/**
 * Helper function to get an nsIDocShell given a context.
 * If the context is a document or window, the corresponding docshell will be
 * returned.
 * If the context is a non-document DOM node, the docshell of its ownerDocument
 * will be returned.
 *
 * @param aContext the context to find a docshell for (can be null)
 *
 * @return a WEAK pointer to the docshell, or nullptr if it could
 *     not be obtained
 *
 * @note  As of this writing, calls to nsIContentPolicy::Should{Load,Process}
 * for TYPE_DOCUMENT and TYPE_SUBDOCUMENT pass in an aContext that either
 * points to the frameElement of the window the load is happening in
 * (in which case NS_CP_GetDocShellFromContext will return the parent of the
 * docshell the load is happening in), or points to the window the load is
 * happening in (in which case NS_CP_GetDocShellFromContext will return
 * the docshell the load is happening in).  It's up to callers to QI aContext
 * and handle things accordingly if they want the docshell the load is
 * happening in.  These are somewhat odd semantics, and bug 466687 has been
 * filed to consider improving them.
 */
inline nsIDocShell* NS_CP_GetDocShellFromContext(nsISupports* aContext) {
  if (!aContext) {
    return nullptr;
  }

  nsCOMPtr<nsPIDOMWindowOuter> window = do_QueryInterface(aContext);

  if (!window) {
    // Our context might be a document.
    nsCOMPtr<mozilla::dom::Document> doc = do_QueryInterface(aContext);
    if (!doc) {
      // we were not a document after all, get our ownerDocument,
      // hopefully
      nsCOMPtr<nsIContent> content = do_QueryInterface(aContext);
      if (content) {
        doc = content->OwnerDoc();
      }
    }

    if (doc) {
      if (doc->GetDisplayDocument()) {
        doc = doc->GetDisplayDocument();
      }

      window = doc->GetWindow();
    }
  }

  if (!window) {
    return nullptr;
  }

  return window->GetDocShell();
}

#endif /* _nsContentPolicyUtils_h_ */