Credentials prototyping

- Remove CredentialsFactory as it's unnecessary
- Effectively make Credentials a channel factory, allowing different credential types to create different channel types - this gives us a hook so that InsecureCredentials can at runtime instantiate a different kind of channel as required - giving us a way of generating an openssl free version of grpc++.
- Server credentials not touched yet, but they'll need to be updated.

3 files changed, 47 insertions, 57 deletions

diff --git a/include/grpc++/channel_arguments.h b/include/grpc++/channel_arguments.h
index 75c3cf45b4..91f89f313e 100644
--- a/include/grpc++/channel_arguments.h
+++ b/include/grpc++/channel_arguments.h
@@ -62,6 +62,9 @@ class ChannelArguments {
   void SetInt(const grpc::string& key, int value);
   void SetString(const grpc::string& key, const grpc::string& value);
 
+  // Populates given channel_args with args_, does not take ownership.
+  void SetChannelArgs(grpc_channel_args* channel_args) const;
+
  private:
   friend class Channel;
   friend class testing::ChannelArgumentsTest;
@@ -73,9 +76,6 @@ class ChannelArguments {
   // Returns empty string when it is not set.
   grpc::string GetSslTargetNameOverride() const;
 
-  // Populates given channel_args with args_, does not take ownership.
-  void SetChannelArgs(grpc_channel_args* channel_args) const;
-
   std::vector<grpc_arg> args_;
   std::list<grpc::string> strings_;
 };
diff --git a/include/grpc++/create_channel.h b/include/grpc++/create_channel.h
index eadabda359..2c40047e9a 100644
--- a/include/grpc++/create_channel.h
+++ b/include/grpc++/create_channel.h
@@ -43,9 +43,6 @@ namespace grpc {
 class ChannelArguments;
 class ChannelInterface;
 
-std::shared_ptr<ChannelInterface> CreateChannel(const grpc::string& target,
-                                                const ChannelArguments& args);
-
 // If creds does not hold an object or is invalid, a lame channel is returned.
 std::shared_ptr<ChannelInterface> CreateChannel(
     const grpc::string& target, const std::unique_ptr<Credentials>& creds,
diff --git a/include/grpc++/credentials.h b/include/grpc++/credentials.h
index ac6f394847..b462b450da 100644
--- a/include/grpc++/credentials.h
+++ b/include/grpc++/credentials.h
@@ -39,29 +39,21 @@
 
 #include <grpc++/config.h>
 
-struct grpc_credentials;
-
 namespace grpc {
+class ChannelArguments;
+class ChannelInterface;
 
-// grpc_credentials wrapper class. Typical use in C++ applications is limited
-// to creating an instance using CredentialsFactory, and passing it down
-// during channel construction.
-
-class Credentials final {
+class Credentials {
  public:
-  ~Credentials();
-
-  // TODO(abhikumar): Specify a plugin API here to be implemented by
-  // credentials that do not have a corresponding implementation in C.
+  virtual ~Credentials();
 
  private:
-  explicit Credentials(grpc_credentials*);
-  grpc_credentials* GetRawCreds();
-
-  friend class Channel;
-  friend class CredentialsFactory;
+  friend std::shared_ptr<ChannelInterface> CreateChannel(
+      const grpc::string& target, const std::unique_ptr<Credentials>& creds,
+      const ChannelArguments& args);
 
-  grpc_credentials* creds_;
+  virtual std::shared_ptr<ChannelInterface> CreateChannel(
+      const grpc::string& target, const ChannelArguments& args) = 0;
 };
 
 // Options used to build SslCredentials
@@ -79,43 +71,44 @@ struct SslCredentialsOptions {
   grpc::string pem_cert_chain;
 };
 
-// Factory for building different types of Credentials
-// The methods may return empty unique_ptr when credentials cannot be created.
+// Factories for building different types of Credentials
+// The functions may return empty unique_ptr when credentials cannot be created.
 // If a Credentials pointer is returned, it can still be invalid when used to
 // create a channel. A lame channel will be created then and all rpcs will
 // fail on it.
-class CredentialsFactory {
- public:
-  // Builds credentials with reasonable defaults.
-  static std::unique_ptr<Credentials> DefaultCredentials();
-
-  // Builds SSL Credentials given SSL specific options
-  static std::unique_ptr<Credentials> SslCredentials(
-      const SslCredentialsOptions& options);
-
-  // Builds credentials for use when running in GCE
-  static std::unique_ptr<Credentials> ComputeEngineCredentials();
-
-  // Builds service account credentials.
-  // json_key is the JSON key string containing the client's private key.
-  // scope is a space-delimited list of the requested permissions.
-  // token_lifetime is the lifetime of each token acquired through this service
-  // account credentials. It should be positive and should not exceed
-  // grpc_max_auth_token_lifetime or will be cropped to this value.
-  static std::unique_ptr<Credentials> ServiceAccountCredentials(
-      const grpc::string& json_key, const grpc::string& scope,
-      std::chrono::seconds token_lifetime);
-
-  // Builds IAM credentials.
-  static std::unique_ptr<Credentials> IAMCredentials(
-      const grpc::string& authorization_token,
-      const grpc::string& authority_selector);
-
-  // Combines two credentials objects into a composite credentials
-  static std::unique_ptr<Credentials> ComposeCredentials(
-      const std::unique_ptr<Credentials>& creds1,
-      const std::unique_ptr<Credentials>& creds2);
-};
+
+// Builds credentials with reasonable defaults.
+std::unique_ptr<Credentials> DefaultCredentials();
+
+// Builds SSL Credentials given SSL specific options
+std::unique_ptr<Credentials> SslCredentials(
+    const SslCredentialsOptions& options);
+
+// Builds credentials for use when running in GCE
+std::unique_ptr<Credentials> ComputeEngineCredentials();
+
+// Builds service account credentials.
+// json_key is the JSON key string containing the client's private key.
+// scope is a space-delimited list of the requested permissions.
+// token_lifetime is the lifetime of each token acquired through this service
+// account credentials. It should be positive and should not exceed
+// grpc_max_auth_token_lifetime or will be cropped to this value.
+std::unique_ptr<Credentials> ServiceAccountCredentials(
+    const grpc::string& json_key, const grpc::string& scope,
+    std::chrono::seconds token_lifetime);
+
+// Builds IAM credentials.
+std::unique_ptr<Credentials> IAMCredentials(
+    const grpc::string& authorization_token,
+    const grpc::string& authority_selector);
+
+// Combines two credentials objects into a composite credentials
+std::unique_ptr<Credentials> ComposeCredentials(
+    const std::unique_ptr<Credentials>& creds1,
+    const std::unique_ptr<Credentials>& creds2);
+
+// Credentials for an unencrypted, unauthenticated channel
+std::unique_ptr<Credentials> InsecureCredentials();
 
 }  // namespace grpc