Do a better job at faking simple challenge signatures.

chromeos/dbus/fake_cryptohome_client.cc

Index: chromeos/dbus/fake_cryptohome_client.cc
diff --git a/chromeos/dbus/fake_cryptohome_client.cc b/chromeos/dbus/fake_cryptohome_client.cc
index 1ec74fdbe3fafc50a73d9552e6ff2d17c978ea9f..30f0a61d6ec18876c9a49b6fbb381e2ace929a2e 100644
--- a/chromeos/dbus/fake_cryptohome_client.cc
+++ b/chromeos/dbus/fake_cryptohome_client.cc
@@ -15,6 +15,7 @@
 #include "base/threading/thread_restrictions.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "chromeos/chromeos_paths.h"
+#include "chromeos/cryptohome/attestation.pb.h"
 #include "chromeos/dbus/cryptohome/key.pb.h"
 #include "chromeos/dbus/cryptohome/rpc.pb.h"
 #include "third_party/cros_system_api/dbus/service_constants.h"
@@ -24,6 +25,13 @@
 
 namespace chromeos {
 
+namespace {
+// Signature nonces are twenty bytes. This matches the attestation code.
+const char kTwentyBytesNonce[] = "+addtwentybytesnonce";

[xiyuan, 2016/09/06 22:32:32]

nit: const -> constexpr

+// A symbolic signature.
+const char kSignature[] = "signed";
+}

[xiyuan, 2016/09/06 22:32:32]

nit: append "// namespace" after the closing }

[The one and only Dr. Crash, 2016/09/07 02:43:47]

Done.

+
 FakeCryptohomeClient::FakeCryptohomeClient()
     : service_is_available_(true),
       async_call_id_(1),
@@ -80,7 +88,7 @@ void FakeCryptohomeClient::AsyncCheckKey(
     const cryptohome::Identification& cryptohome_id,
     const std::string& key,
     const AsyncMethodCallback& callback) {
-  ReturnAsyncMethodResult(callback, false);
+  ReturnAsyncMethodResult(callback);
 }
 
 void FakeCryptohomeClient::AsyncMigrateKey(
@@ -88,13 +96,13 @@ void FakeCryptohomeClient::AsyncMigrateKey(
     const std::string& from_key,
     const std::string& to_key,
     const AsyncMethodCallback& callback) {
-  ReturnAsyncMethodResult(callback, false);
+  ReturnAsyncMethodResult(callback);
 }
 
 void FakeCryptohomeClient::AsyncRemove(
     const cryptohome::Identification& cryptohome_id,
     const AsyncMethodCallback& callback) {
-  ReturnAsyncMethodResult(callback, false);
+  ReturnAsyncMethodResult(callback);
 }
 
 void FakeCryptohomeClient::RenameCryptohome(
@@ -143,7 +151,7 @@ void FakeCryptohomeClient::AsyncMount(
     const std::string& key,
     int flags,
     const AsyncMethodCallback& callback) {
-  ReturnAsyncMethodResult(callback, false);
+  ReturnAsyncMethodResult(callback);
 }
 
 void FakeCryptohomeClient::AsyncAddKey(
@@ -151,19 +159,19 @@ void FakeCryptohomeClient::AsyncAddKey(
     const std::string& key,
     const std::string& new_key,
     const AsyncMethodCallback& callback) {
-  ReturnAsyncMethodResult(callback, false);
+  ReturnAsyncMethodResult(callback);
 }
 
 void FakeCryptohomeClient::AsyncMountGuest(
     const AsyncMethodCallback& callback) {
-  ReturnAsyncMethodResult(callback, false);
+  ReturnAsyncMethodResult(callback);
 }
 
 void FakeCryptohomeClient::AsyncMountPublic(
     const cryptohome::Identification& public_mount_id,
     int flags,
     const AsyncMethodCallback& callback) {
-  ReturnAsyncMethodResult(callback, false);
+  ReturnAsyncMethodResult(callback);
 }
 
 void FakeCryptohomeClient::TpmIsReady(
@@ -366,14 +374,14 @@ void FakeCryptohomeClient::TpmAttestationIsEnrolled(
 void FakeCryptohomeClient::AsyncTpmAttestationCreateEnrollRequest(
     chromeos::attestation::PrivacyCAType pca_type,
     const AsyncMethodCallback& callback) {
-  ReturnAsyncMethodResult(callback, true);
+  ReturnAsyncMethodData(callback, std::string());
 }
 
 void FakeCryptohomeClient::AsyncTpmAttestationEnroll(
     chromeos::attestation::PrivacyCAType pca_type,
     const std::string& pca_response,
     const AsyncMethodCallback& callback) {
-  ReturnAsyncMethodResult(callback, false);
+  ReturnAsyncMethodResult(callback);
 }
 
 void FakeCryptohomeClient::AsyncTpmAttestationCreateCertRequest(
@@ -382,7 +390,7 @@ void FakeCryptohomeClient::AsyncTpmAttestationCreateCertRequest(
     const cryptohome::Identification& cryptohome_id,
     const std::string& request_origin,
     const AsyncMethodCallback& callback) {
-  ReturnAsyncMethodResult(callback, true);
+  ReturnAsyncMethodData(callback, std::string());
 }
 
 void FakeCryptohomeClient::AsyncTpmAttestationFinishCertRequest(
@@ -391,7 +399,7 @@ void FakeCryptohomeClient::AsyncTpmAttestationFinishCertRequest(
     const cryptohome::Identification& cryptohome_id,
     const std::string& key_name,
     const AsyncMethodCallback& callback) {
-  ReturnAsyncMethodResult(callback, true);
+  ReturnAsyncMethodData(callback, std::string());
 }
 
 void FakeCryptohomeClient::TpmAttestationDoesKeyExist(
@@ -428,7 +436,7 @@ void FakeCryptohomeClient::TpmAttestationRegisterKey(
     const cryptohome::Identification& cryptohome_id,
     const std::string& key_name,
     const AsyncMethodCallback& callback) {
-  ReturnAsyncMethodResult(callback, true);
+  ReturnAsyncMethodData(callback, std::string());
 }
 
 void FakeCryptohomeClient::TpmAttestationSignEnterpriseChallenge(
@@ -440,7 +448,7 @@ void FakeCryptohomeClient::TpmAttestationSignEnterpriseChallenge(
     attestation::AttestationChallengeOptions options,
     const std::string& challenge,
     const AsyncMethodCallback& callback) {
-  ReturnAsyncMethodResult(callback, true);
+  ReturnAsyncMethodData(callback, std::string());
 }
 
 void FakeCryptohomeClient::TpmAttestationSignSimpleChallenge(
@@ -449,7 +457,10 @@ void FakeCryptohomeClient::TpmAttestationSignSimpleChallenge(
     const std::string& key_name,
     const std::string& challenge,
     const AsyncMethodCallback& callback) {
-  ReturnAsyncMethodResult(callback, true);
+  cryptohome::SignedData signed_data;
+  signed_data.set_data(challenge + kTwentyBytesNonce);
+  signed_data.set_signature(kSignature);
+  ReturnAsyncMethodData(callback, signed_data.SerializeAsString());
 }
 
 void FakeCryptohomeClient::TpmAttestationGetKeyPayload(
@@ -588,26 +599,41 @@ void FakeCryptohomeClient::ReturnProtobufMethodCallback(
 }
 
 void FakeCryptohomeClient::ReturnAsyncMethodResult(
-    const AsyncMethodCallback& callback,
-    bool returns_data) {
+    const AsyncMethodCallback& callback) {
   base::ThreadTaskRunnerHandle::Get()->PostTask(
       FROM_HERE,
       base::Bind(&FakeCryptohomeClient::ReturnAsyncMethodResultInternal,
-                 weak_ptr_factory_.GetWeakPtr(), callback, returns_data));
+                 weak_ptr_factory_.GetWeakPtr(), callback));
 }
 
-void FakeCryptohomeClient::ReturnAsyncMethodResultInternal(
+void FakeCryptohomeClient::ReturnAsyncMethodData(
     const AsyncMethodCallback& callback,
-    bool returns_data) {
+    const std::string& data) {
+  base::ThreadTaskRunnerHandle::Get()->PostTask(
+      FROM_HERE,
+      base::Bind(&FakeCryptohomeClient::ReturnAsyncMethodDataInternal,
+                 weak_ptr_factory_.GetWeakPtr(), callback, data));
+}
+
+void FakeCryptohomeClient::ReturnAsyncMethodResultInternal(
+    const AsyncMethodCallback& callback) {
   callback.Run(async_call_id_);
-  if (!returns_data && !async_call_status_handler_.is_null()) {
+  if (!async_call_status_handler_.is_null()) {
     base::ThreadTaskRunnerHandle::Get()->PostTask(
         FROM_HERE, base::Bind(async_call_status_handler_, async_call_id_, true,
                               cryptohome::MOUNT_ERROR_NONE));
-  } else if (returns_data && !async_call_status_data_handler_.is_null()) {
+  }
+  ++async_call_id_;
+}
+
+void FakeCryptohomeClient::ReturnAsyncMethodDataInternal(
+    const AsyncMethodCallback& callback,
+    const std::string& data) {
+  callback.Run(async_call_id_);
+  if (!async_call_status_data_handler_.is_null()) {
     base::ThreadTaskRunnerHandle::Get()->PostTask(
         FROM_HERE, base::Bind(async_call_status_data_handler_, async_call_id_,
-                              true, std::string()));
+                              true, data));
   }
   ++async_call_id_;
 }