text: // 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.
  
  #include "sync/internal_api/syncapi_internal.h"
  
  #include "base/memory/scoped_ptr.h"
  #include "sync/protocol/password_specifics.pb.h"
  #include "sync/protocol/sync.pb.h"
  #include "sync/util/cryptographer.h"
  
  namespace syncer {
  
  namespace {
  
  bool EndsWithSpace(const std::string& string) {
    return !string.empty() && *string.rbegin() == ' ';
  }
  
  }
  
  sync_pb::PasswordSpecificsData* DecryptPasswordSpecifics(
      const sync_pb::EntitySpecifics& specifics, Cryptographer* crypto) {
    if (!specifics.has_password())
      return NULL;
    const sync_pb::PasswordSpecifics& password_specifics = specifics.password();
    if (!password_specifics.has_encrypted())
      return NULL;
    const sync_pb::EncryptedData& encrypted = password_specifics.encrypted();
    scoped_ptr<sync_pb::PasswordSpecificsData> data(
        new sync_pb::PasswordSpecificsData);
    if (!crypto->Decrypt(encrypted, data.get()))
      return NULL;
    return data.release();
  }
  
  // The list of names which are reserved for use by the server.
  static const char* kForbiddenServerNames[] = { "", ".", ".." };
  
  // When taking a name from the syncapi, append a space if it matches the
  // pattern of a server-illegal name followed by zero or more spaces.
  void SyncAPINameToServerName(const std::string& syncer_name,
                               std::string* out) {
    *out = syncer_name;
    if (IsNameServerIllegalAfterTrimming(*out))
      out->append(" ");
  }
  
  // In the reverse direction, if a server name matches the pattern of a
  // server-illegal name followed by one or more spaces, remove the trailing
  // space.
  void ServerNameToSyncAPIName(const std::string& server_name,
                               std::string* out) {
    CHECK(out);
    int length_to_copy = server_name.length();
    if (IsNameServerIllegalAfterTrimming(server_name) &&
        EndsWithSpace(server_name)) {
      --length_to_copy;
    }
    *out = server_name.substr(0, length_to_copy);
  }
  
  // Checks whether |name| is a server-illegal name followed by zero or more space
  // characters.  The three server-illegal names are the empty string, dot, and
  // dot-dot.  Very long names (>255 bytes in UTF-8 Normalization Form C) are
  // also illegal, but are not considered here.
  bool IsNameServerIllegalAfterTrimming(const std::string& name) {
    size_t untrimmed_count = name.find_last_not_of(' ') + 1;
    for (size_t i = 0; i < arraysize(kForbiddenServerNames); ++i) {
      if (name.compare(0, untrimmed_count, kForbiddenServerNames[i]) == 0)
        return true;
    }
    return false;
  }
  
  // Compare the values of two EntitySpecifics, accounting for encryption.
  bool AreSpecificsEqual(const Cryptographer* cryptographer,
                         const sync_pb::EntitySpecifics& left,
                         const sync_pb::EntitySpecifics& right) {
    // Note that we can't compare encrypted strings directly as they are seeded
    // with a random value.
    std::string left_plaintext, right_plaintext;
    if (left.has_encrypted()) {
      if (!cryptographer->CanDecrypt(left.encrypted())) {
        NOTREACHED() << "Attempting to compare undecryptable data.";
        return false;
      }
      left_plaintext = cryptographer->DecryptToString(left.encrypted());
    } else {
      left_plaintext = left.SerializeAsString();
    }
    if (right.has_encrypted()) {
      if (!cryptographer->CanDecrypt(right.encrypted())) {
        NOTREACHED() << "Attempting to compare undecryptable data.";
        return false;
      }
      right_plaintext = cryptographer->DecryptToString(right.encrypted());
    } else {
      right_plaintext = right.SerializeAsString();
    }
    if (left_plaintext == right_plaintext) {
      return true;
    }
    return false;
  }
  
  }  // namespace syncer
  