gecko-dev/dom/u2f/U2FManager.h

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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/. */

#ifndef mozilla_dom_U2FManager_h
#define mozilla_dom_U2FManager_h

#include "U2FAuthenticator.h"
#include "mozilla/MozPromise.h"
#include "mozilla/dom/Event.h"
#include "mozilla/dom/PWebAuthnTransaction.h"
#include "nsIDOMEventListener.h"

/*
 * Content process manager for the U2F protocol. Created on calls to the
 * U2F DOM object, this manager handles establishing IPC channels
 * for U2F transactions, as well as keeping track of MozPromise objects
 * representing transactions in flight.
 *
 * The U2F spec (http://fidoalliance.org/specs/fido-u2f-v1.1-id-20160915.zip)
 * allows for two different types of transactions: registration and signing.
 * When either of these is requested via the DOM API, the following steps are
 * executed in the U2FManager:
 *
 * - Validation of the request. Return a failed promise to the caller if request
 *   does not have correct parameters.
 *
 * - If request is valid, open a new IPC channel for running the transaction. If
 *   another transaction is already running in this content process, cancel it.
 *   Return a pending promise to the caller.
 *
 * - Send transaction information to parent process (by running the Start*
 *   functions of U2FManager). Assuming another transaction is currently in
 *   flight in another content process, parent will handle canceling it.
 *
 * - On return of successful transaction information from parent process, turn
 *   information into DOM object format required by spec, and resolve promise
 *   (by running the Finish* functions of U2FManager). On cancellation request
 *   from parent, reject promise with corresponding error code. Either
 *   outcome will also close the IPC channel.
 *
 */

namespace mozilla {
namespace dom {

class ArrayBufferViewOrArrayBuffer;
class OwningArrayBufferViewOrArrayBuffer;
class Promise;
class U2FTransactionChild;
class U2FTransactionInfo;

class U2FTransaction
{
public:
  U2FTransaction(nsPIDOMWindowInner* aParent,
                 const WebAuthnTransactionInfo&& aInfo,
                 const nsCString& aClientData)
    : mParent(aParent)
    , mInfo(aInfo)
    , mClientData(aClientData)
    , mId(NextId())
  {
    MOZ_ASSERT(mId > 0);
  }

  // Parent of the context we're running the transaction in.
  nsCOMPtr<nsPIDOMWindowInner> mParent;

  // JS Promise representing the transaction status.
  MozPromiseHolder<U2FPromise> mPromise;

  // Holds the parameters of the current transaction, as we need them both
  // before the transaction request is sent, and on successful return.
  WebAuthnTransactionInfo mInfo;

  // Client data used to assemble reply objects.
  nsCString mClientData;

  // Unique transaction id.
  uint64_t mId;

private:
  // Generates a unique id for new transactions. This doesn't have to be unique
  // forever, it's sufficient to differentiate between temporally close
  // transactions, where messages can intersect. Can overflow.
  static uint64_t NextId() {
    static uint64_t id = 0;
    return ++id;
  }
};

class U2FManager final : public nsIDOMEventListener
{
public:
  NS_DECL_ISUPPORTS
  NS_DECL_NSIDOMEVENTLISTENER

  static U2FManager* GetOrCreate();
  static U2FManager* Get();

  already_AddRefed<U2FPromise> Register(nsPIDOMWindowInner* aParent,
              const nsCString& aRpId,
              const nsCString& aClientDataJSON,
              const uint32_t& aTimeoutMillis,
              const nsTArray<WebAuthnScopedCredentialDescriptor>& aExcludeList);
  already_AddRefed<U2FPromise> Sign(nsPIDOMWindowInner* aParent,
              const nsCString& aRpId,
              const nsCString& aClientDataJSON,
              const uint32_t& aTimeoutMillis,
              const nsTArray<WebAuthnScopedCredentialDescriptor>& aKeyList);

  void FinishRegister(const uint64_t& aTransactionId,
                      nsTArray<uint8_t>& aRegBuffer);
  void FinishSign(const uint64_t& aTransactionId,
                  nsTArray<uint8_t>& aCredentialId,
                  nsTArray<uint8_t>& aSigBuffer);
  void RequestAborted(const uint64_t& aTransactionId, const nsresult& aError);

  // XXX This is exposed only until we fix bug 1410346.
  void MaybeCancelTransaction(const nsresult& aError) {
    if (mTransaction.isSome()) {
      CancelTransaction(NS_ERROR_ABORT);
    }
  }

  void ActorDestroyed();

private:
  U2FManager();
  virtual ~U2FManager();

  static nsresult
  BuildTransactionHashes(const nsCString& aRpId,
                         const nsCString& aClientDataJSON,
                         /* out */ CryptoBuffer& aRpIdHash,
                         /* out */ CryptoBuffer& aClientDataHash);

  // Clears all information we have about the current transaction.
  void ClearTransaction();
  // Rejects the current transaction and calls ClearTransaction().
  void RejectTransaction(const nsresult& aError);
  // Cancels the current transaction (by sending a Cancel message to the
  // parent) and rejects it by calling RejectTransaction().
  void CancelTransaction(const nsresult& aError);

  bool MaybeCreateBackgroundActor();

  // IPC Channel to the parent process.
  RefPtr<U2FTransactionChild> mChild;

  // The current transaction, if any.
  Maybe<U2FTransaction> mTransaction;
};

} // namespace dom
} // namespace mozilla

#endif // mozilla_dom_U2FManager_h