firebase-ios-sdk/FirebaseAppDistribution/Sources/FIRAppDistributionAuthPersistence.m

// Copyright 2020 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#import <GoogleUtilities/GULKeychainUtils.h>
#import "FIRAppDistributionAuthPersistence+Private.h"

NS_ASSUME_NONNULL_BEGIN

NSString *const kFIRAppDistributionAuthPersistenceErrorDomain =
    @"com.firebase.app_distribution.auth_persistence";

static NSString *const kFIRAppDistributionAuthPersistenceErrorKeychainId =
    @"com.firebase.app_distribution.keychain_id";

@interface FIRAppDistributionAuthPersistence ()
@property(nonatomic, readonly) NSString *appID;
@end

@implementation FIRAppDistributionAuthPersistence

- (instancetype)initWithAppId:(NSString *)appID {
  self = [super init];
  if (self) {
    _appID = appID;
  }
  return self;
}

- (void)handleAuthStateError:(NSError **_Nullable)error
                 description:(NSString *)description
                        code:(FIRAppDistributionKeychainError)code
             underlyingError:(NSError *_Nullable)underlyingError {
  if (error) {
    NSDictionary *userInfo =
        underlyingError
            ? @{NSLocalizedDescriptionKey : description, NSUnderlyingErrorKey : underlyingError}
            : @{NSLocalizedDescriptionKey : description};
    *error = [NSError errorWithDomain:kFIRAppDistributionAuthPersistenceErrorDomain
                                 code:code
                             userInfo:userInfo];
  }
}

- (BOOL)clearAuthState:(NSError **_Nullable)error {
  NSMutableDictionary *keychainQuery = [self getKeyChainQuery];
  NSError *keychainError;
  BOOL success = [GULKeychainUtils removeItemWithQuery:keychainQuery error:&keychainError];

  if (!success) {
    NSString *description = NSLocalizedString(
        @"Failed to clear auth state from keychain. Tester will overwrite data on sign in.",
        @"Error message for failure to retrieve auth state from keychain");
    [self handleAuthStateError:error
                   description:description
                          code:FIRAppDistributionErrorTokenDeletionFailure
               underlyingError:keychainError];
    return NO;
  }

  return YES;
}

- (OIDAuthState *)retrieveAuthState:(NSError **_Nullable)error {
  NSMutableDictionary *keychainQuery = [self getKeyChainQuery];
  [keychainQuery setObject:(id)kCFBooleanTrue forKey:(id)kSecReturnData];
  [keychainQuery setObject:(id)kSecMatchLimitOne forKey:(id)kSecMatchLimit];

  NSError *keychainError;
  NSData *passwordData = [GULKeychainUtils getItemWithQuery:keychainQuery error:&keychainError];
  NSData *result = nil;

  if (!passwordData) {
    if (keychainError) {
      NSString *description = NSLocalizedString(
          @"Failed to retrieve auth state from keychain. Tester will have to sign in again.",
          @"Error message for failure to retrieve auth state from keychain. ");
      [self handleAuthStateError:error
                     description:description
                            code:FIRAppDistributionErrorTokenRetrievalFailure
                 underlyingError:keychainError];
    }
    return nil;
  }

  result = [passwordData copy];

  if (!result) {
    NSString *description =
        NSLocalizedString(@"Failed to unarchive auth state. Tester will have to sign in again.",
                          @"Error message for failure to retrieve auth state from keychain");
    [self handleAuthStateError:error
                   description:description
                          code:FIRAppDistributionErrorTokenRetrievalFailure
               underlyingError:nil];
    return nil;
  }

  OIDAuthState *authState = [FIRAppDistributionAuthPersistence unarchiveKeychainResult:result];

  return authState;
}

- (BOOL)persistAuthState:(OIDAuthState *)authState error:(NSError **_Nullable)error {
  NSData *authorizationData = [FIRAppDistributionAuthPersistence archiveDataForKeychain:authState];
  NSMutableDictionary *keychainQuery = [self getKeyChainQuery];
  NSError *keychainError;
  // setItem performs an up-sert. Will automatically update the keychain entry if it already
  // exists.
  BOOL success = [GULKeychainUtils setItem:authorizationData
                                 withQuery:keychainQuery
                                     error:&keychainError];

  if (!success) {
    NSString *description = NSLocalizedString(
        @"Failed to persist auth state. Tester will have to sign in again after app close.",
        @"Error message for failure to persist auth state to keychain");

    [self handleAuthStateError:error
                   description:description
                          code:FIRAppDistributionErrorTokenPersistenceFailure
               underlyingError:keychainError];
    return NO;
  }

  return YES;
}

- (NSMutableDictionary *)getKeyChainQuery {
  NSMutableDictionary *keychainQuery = [@{
    (id)kSecClass : (id)kSecClassGenericPassword,
    (id)kSecAttrGeneric : kFIRAppDistributionAuthPersistenceErrorKeychainId,
    (id)kSecAttrAccount : [self keychainID],
    (id)kSecAttrService : [self keychainID]
  } mutableCopy];

  return keychainQuery;
}

- (NSString *)keychainID {
  return [NSString
      stringWithFormat:@"fad-auth-%@-%@", [[NSBundle mainBundle] bundleIdentifier], self.appID];
}

+ (OIDAuthState *)unarchiveKeychainResult:(NSData *)result {
  return (OIDAuthState *)[NSKeyedUnarchiver unarchiveObjectWithData:result];
}

+ (NSData *)archiveDataForKeychain:(OIDAuthState *)data {
  return [NSKeyedArchiver archivedDataWithRootObject:data];
}

@end

NS_ASSUME_NONNULL_END