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Add failure reasons for App Attest error cases #32

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merged 1 commit into from
Oct 24, 2023
Merged

Add failure reasons for App Attest error cases #32

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57 changes: 36 additions & 21 deletions AppCheckCore/Sources/AppAttestProvider/GACAppAttestProvider.m
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Original file line number Diff line number Diff line change
Expand Up @@ -318,16 +318,21 @@ - (void)getTokenWithLimitedUse:(BOOL)limitedUse
do:^NSData *_Nullable {
return [GACAppCheckCryptoUtils sha256HashFromData:challenge];
}]
.thenOn(
self.queue,
^FBLPromise<NSData *> *(NSData *challengeHash) {
return [FBLPromise onQueue:self.queue
wrapObjectOrErrorCompletion:^(FBLPromiseObjectOrErrorCompletion _Nonnull handler) {
[self.appAttestService attestKey:keyID
clientDataHash:challengeHash
completionHandler:handler];
}];
})
.thenOn(self.queue,
^FBLPromise<NSData *> *(NSData *challengeHash) {
return [FBLPromise onQueue:self.queue
wrapObjectOrErrorCompletion:^(
FBLPromiseObjectOrErrorCompletion _Nonnull handler) {
[self.appAttestService attestKey:keyID
clientDataHash:challengeHash
completionHandler:handler];
}]
.recoverOn(self.queue, ^id(NSError *error) {
return [GACAppCheckErrorUtil appAttestAttestKeyFailedWithError:error
keyId:keyID
clientDataHash:challengeHash];
});
})
.thenOn(self.queue, ^FBLPromise<GACAppAttestKeyAttestationResult *> *(NSData *attestation) {
GACAppAttestKeyAttestationResult *result =
[[GACAppAttestKeyAttestationResult alloc] initWithKeyID:keyID
Expand Down Expand Up @@ -433,17 +438,23 @@ - (void)getTokenWithLimitedUse:(BOOL)limitedUse
// 1.2. Get the statement SHA256 hash.
return [GACAppCheckCryptoUtils sha256HashFromData:[statementForAssertion copy]];
}]
.thenOn(
self.queue,
^FBLPromise<NSData *> *(NSData *statementHash) {
// 2. Generate App Attest assertion.
return [FBLPromise onQueue:self.queue
wrapObjectOrErrorCompletion:^(FBLPromiseObjectOrErrorCompletion _Nonnull handler) {
[self.appAttestService generateAssertion:keyID
clientDataHash:statementHash
completionHandler:handler];
}];
})
.thenOn(self.queue,
^FBLPromise<NSData *> *(NSData *statementHash) {
// 2. Generate App Attest assertion.
return [FBLPromise onQueue:self.queue
wrapObjectOrErrorCompletion:^(
FBLPromiseObjectOrErrorCompletion _Nonnull handler) {
[self.appAttestService generateAssertion:keyID
clientDataHash:statementHash
completionHandler:handler];
}]
.recoverOn(self.queue, ^id(NSError *error) {
return [GACAppCheckErrorUtil
appAttestGenerateAssertionFailedWithError:error
keyId:keyID
clientDataHash:statementHash];
});
})
// 3. Compose the result object.
.thenOn(self.queue, ^GACAppAttestAssertionData *(NSData *assertion) {
return [[GACAppAttestAssertionData alloc] initWithChallenge:challenge
Expand Down Expand Up @@ -521,6 +532,10 @@ - (void)getTokenWithLimitedUse:(BOOL)limitedUse
wrapObjectOrErrorCompletion:^(FBLPromiseObjectOrErrorCompletion _Nonnull handler) {
[self.appAttestService generateKeyWithCompletionHandler:handler];
}]
.recoverOn(self.queue,
^id(NSError *error) {
return [GACAppCheckErrorUtil appAttestGenerateKeyFailedWithError:error];
})
.thenOn(self.queue, ^FBLPromise<NSString *> *(NSString *keyID) {
return [self.keyIDStorage setAppAttestKeyID:keyID];
});
Expand Down
12 changes: 12 additions & 0 deletions AppCheckCore/Sources/Core/Errors/GACAppCheckErrorUtil.h
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Original file line number Diff line number Diff line change
Expand Up @@ -49,8 +49,20 @@ void GACAppCheckSetErrorToPointer(NSError *error, NSError **pointer);

+ (NSError *)unsupportedAttestationProvider:(NSString *)providerName;

// MARK: - App Attest Errors

+ (NSError *)appAttestKeyIDNotFound;

+ (NSError *)appAttestGenerateKeyFailedWithError:(NSError *)error;

+ (NSError *)appAttestAttestKeyFailedWithError:(NSError *)error
keyId:(NSString *)keyId
clientDataHash:(NSData *)clientDataHash;

+ (NSError *)appAttestGenerateAssertionFailedWithError:(NSError *)error
keyId:(NSString *)keyId
clientDataHash:(NSData *)clientDataHash;

@end

NS_ASSUME_NONNULL_END
43 changes: 41 additions & 2 deletions AppCheckCore/Sources/Core/Errors/GACAppCheckErrorUtil.m
View file
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Original file line number Diff line number Diff line change
Expand Up @@ -105,17 +105,56 @@ + (NSError *)unsupportedAttestationProvider:(NSString *)providerName {
underlyingError:nil];
}

+ (NSError *)errorWithFailureReason:(NSString *)failureReason {
return [self appCheckErrorWithCode:GACAppCheckErrorCodeUnknown
failureReason:failureReason
underlyingError:nil];
}

#pragma mark - App Attest

+ (NSError *)appAttestKeyIDNotFound {
NSString *failureReason = [NSString stringWithFormat:@"App attest key ID not found."];
return [self appCheckErrorWithCode:GACAppCheckErrorCodeUnknown
failureReason:failureReason
underlyingError:nil];
}

+ (NSError *)errorWithFailureReason:(NSString *)failureReason {
+ (NSError *)appAttestGenerateKeyFailedWithError:(NSError *)error {
NSString *failureReason = @"Failed to generate a new cryptographic key for use with the App "
@"Attest service (`generateKeyWithCompletionHandler:`).";
// TODO(#31): Add a new error code for this case (e.g., GACAppCheckAppAttestGenerateKeyFailed).
return [self appCheckErrorWithCode:GACAppCheckErrorCodeUnknown
failureReason:failureReason
underlyingError:nil];
underlyingError:error];
}

+ (NSError *)appAttestAttestKeyFailedWithError:(NSError *)error
keyId:(NSString *)keyId
clientDataHash:(NSData *)clientDataHash {
NSString *failureReason =
[NSString stringWithFormat:@"Failed to attest the validity of the generated cryptographic "
@"key (`attestKey:clientDataHash:completionHandler:`); "
@"keyId.length = %lu, clientDataHash.length = %lu",
keyId.length, clientDataHash.length];
// TODO(#31): Add a new error code for this case (e.g., GACAppCheckAppAttestAttestKeyFailed).
return [self appCheckErrorWithCode:GACAppCheckErrorCodeUnknown
failureReason:failureReason
underlyingError:error];
}

+ (NSError *)appAttestGenerateAssertionFailedWithError:(NSError *)error
keyId:(NSString *)keyId
clientDataHash:(NSData *)clientDataHash {
NSString *failureReason = [NSString
stringWithFormat:@"Failed to create a block of data that demonstrates the legitimacy of the "
@"app instance (`generateAssertion:clientDataHash:completionHandler:`); "
@"keyId.length = %lu, clientDataHash.length = %lu.",
keyId.length, clientDataHash.length];
// TODO(#31): Add error code for this case (e.g., GACAppCheckAppAttestGenerateAssertionFailed).
return [self appCheckErrorWithCode:GACAppCheckErrorCodeUnknown
failureReason:failureReason
underlyingError:error];
}

#pragma mark - Helpers
Expand Down
14 changes: 11 additions & 3 deletions AppCheckCore/Tests/Unit/AppAttestProvider/GACAppAttestProviderTests.m
View file
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Original file line number Diff line number Diff line change
Expand Up @@ -390,6 +390,10 @@ - (void)testGetToken_WhenUnregisteredKeyAndKeyAttestationError {
NSError *attestationError = [NSError errorWithDomain:@"testGetTokenWhenKeyAttestationError"
code:0
userInfo:nil];
NSError *expectedError =
[GACAppCheckErrorUtil appAttestAttestKeyFailedWithError:attestationError
keyId:existingKeyID
clientDataHash:self.randomChallengeHash];
id attestCompletionArg = [OCMArg invokeBlockWithArgs:[NSNull null], attestationError, nil];
OCMExpect([self.mockAppAttestService attestKey:existingKeyID
clientDataHash:self.randomChallengeHash
Expand All @@ -410,7 +414,7 @@ - (void)testGetToken_WhenUnregisteredKeyAndKeyAttestationError {
[completionExpectation fulfill];

XCTAssertNil(token);
XCTAssertEqualObjects(error, attestationError);
XCTAssertEqualObjects(error, expectedError);
}];

[self waitForExpectations:@[ self.fakeBackoffWrapper.backoffExpectation, completionExpectation ]
Expand All @@ -421,7 +425,7 @@ - (void)testGetToken_WhenUnregisteredKeyAndKeyAttestationError {
[self verifyAllMocks];

// 9. Verify backoff error.
XCTAssertEqualObjects(self.fakeBackoffWrapper.operationError, attestationError);
XCTAssertEqualObjects(self.fakeBackoffWrapper.operationError, expectedError);
}

- (void)testGetToken_WhenUnregisteredKeyAndKeyAttestationExchangeError {
Expand Down Expand Up @@ -697,6 +701,10 @@ - (void)testGetToken_WhenKeyRegisteredAndGenerateAssertionError {
[NSError errorWithDomain:@"testGetToken_WhenKeyRegisteredAndGenerateAssertionError"
code:0
userInfo:nil];
NSError *expectedError =
[GACAppCheckErrorUtil appAttestGenerateAssertionFailedWithError:generateAssertionError
keyId:existingKeyID
clientDataHash:self.randomChallengeHash];
id completionBlockArg = [OCMArg invokeBlockWithArgs:[NSNull null], generateAssertionError, nil];
OCMExpect([self.mockAppAttestService
generateAssertion:existingKeyID
Expand All @@ -718,7 +726,7 @@ - (void)testGetToken_WhenKeyRegisteredAndGenerateAssertionError {
[completionExpectation fulfill];

XCTAssertNil(token);
XCTAssertEqualObjects(error, generateAssertionError);
XCTAssertEqualObjects(error, expectedError);
}];

[self waitForExpectations:@[ completionExpectation ] timeout:0.5];
Expand Down