/*
 *
 * Copyright 2015 gRPC authors.
 *
 * 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.
 *
 */

#ifndef GRPC_CORE_LIB_SECURITY_TRANSPORT_SECURITY_CONNECTOR_H
#define GRPC_CORE_LIB_SECURITY_TRANSPORT_SECURITY_CONNECTOR_H

#include <stdbool.h>

#include <grpc/grpc_security.h>

#include "src/core/lib/channel/handshaker.h"
#include "src/core/lib/iomgr/endpoint.h"
#include "src/core/lib/iomgr/tcp_server.h"
#include "src/core/tsi/ssl_transport_security.h"
#include "src/core/tsi/transport_security_interface.h"

#ifndef NDEBUG
extern grpc_tracer_flag grpc_trace_security_connector_refcount;
#endif

/* --- status enum. --- */

typedef enum { GRPC_SECURITY_OK = 0, GRPC_SECURITY_ERROR } grpc_security_status;

/* --- URL schemes. --- */

#define GRPC_SSL_URL_SCHEME "https"
#define GRPC_FAKE_SECURITY_URL_SCHEME "http+fake_security"

/* --- security_connector object. ---

    A security connector object represents away to configure the underlying
    transport security mechanism and check the resulting trusted peer.  */

typedef struct grpc_security_connector grpc_security_connector;

#define GRPC_ARG_SECURITY_CONNECTOR "grpc.security_connector"

typedef struct {
  void (*destroy)(grpc_exec_ctx *exec_ctx, grpc_security_connector *sc);
  void (*check_peer)(grpc_exec_ctx *exec_ctx, grpc_security_connector *sc,
                     tsi_peer peer, grpc_auth_context **auth_context,
                     grpc_closure *on_peer_checked);
} grpc_security_connector_vtable;

typedef struct grpc_security_connector_handshake_list {
  void *handshake;
  struct grpc_security_connector_handshake_list *next;
} grpc_security_connector_handshake_list;

struct grpc_security_connector {
  const grpc_security_connector_vtable *vtable;
  gpr_refcount refcount;
  const char *url_scheme;
};

/* Refcounting. */
#ifndef NDEBUG
#define GRPC_SECURITY_CONNECTOR_REF(p, r) \
  grpc_security_connector_ref((p), __FILE__, __LINE__, (r))
#define GRPC_SECURITY_CONNECTOR_UNREF(exec_ctx, p, r) \
  grpc_security_connector_unref((exec_ctx), (p), __FILE__, __LINE__, (r))
grpc_security_connector *grpc_security_connector_ref(
    grpc_security_connector *policy, const char *file, int line,
    const char *reason);
void grpc_security_connector_unref(grpc_exec_ctx *exec_ctx,
                                   grpc_security_connector *policy,
                                   const char *file, int line,
                                   const char *reason);
#else
#define GRPC_SECURITY_CONNECTOR_REF(p, r) grpc_security_connector_ref((p))
#define GRPC_SECURITY_CONNECTOR_UNREF(exec_ctx, p, r) \
  grpc_security_connector_unref((exec_ctx), (p))
grpc_security_connector *grpc_security_connector_ref(
    grpc_security_connector *policy);
void grpc_security_connector_unref(grpc_exec_ctx *exec_ctx,
                                   grpc_security_connector *policy);
#endif

/* Check the peer. Callee takes ownership of the peer object.
   When done, sets *auth_context and invokes on_peer_checked. */
void grpc_security_connector_check_peer(grpc_exec_ctx *exec_ctx,
                                        grpc_security_connector *sc,
                                        tsi_peer peer,
                                        grpc_auth_context **auth_context,
                                        grpc_closure *on_peer_checked);

/* Util to encapsulate the connector in a channel arg. */
grpc_arg grpc_security_connector_to_arg(grpc_security_connector *sc);

/* Util to get the connector from a channel arg. */
grpc_security_connector *grpc_security_connector_from_arg(const grpc_arg *arg);

/* Util to find the connector from channel args. */
grpc_security_connector *grpc_security_connector_find_in_args(
    const grpc_channel_args *args);

/* --- channel_security_connector object. ---

    A channel security connector object represents away to configure the
    underlying transport security mechanism on the client side.  */

typedef struct grpc_channel_security_connector grpc_channel_security_connector;

struct grpc_channel_security_connector {
  grpc_security_connector base;
  grpc_call_credentials *request_metadata_creds;
  bool (*check_call_host)(grpc_exec_ctx *exec_ctx,
                          grpc_channel_security_connector *sc, const char *host,
                          grpc_auth_context *auth_context,
                          grpc_closure *on_call_host_checked,
                          grpc_error **error);
  void (*cancel_check_call_host)(grpc_exec_ctx *exec_ctx,
                                 grpc_channel_security_connector *sc,
                                 grpc_closure *on_call_host_checked,
                                 grpc_error *error);
  void (*add_handshakers)(grpc_exec_ctx *exec_ctx,
                          grpc_channel_security_connector *sc,
                          grpc_handshake_manager *handshake_mgr);
};

/// Checks that the host that will be set for a call is acceptable.
/// Returns true if completed synchronously, in which case \a error will
/// be set to indicate the result.  Otherwise, \a on_call_host_checked
/// will be invoked when complete.
bool grpc_channel_security_connector_check_call_host(
    grpc_exec_ctx *exec_ctx, grpc_channel_security_connector *sc,
    const char *host, grpc_auth_context *auth_context,
    grpc_closure *on_call_host_checked, grpc_error **error);

/// Cancels a pending asychronous call to
/// grpc_channel_security_connector_check_call_host() with
/// \a on_call_host_checked as its callback.
void grpc_channel_security_connector_cancel_check_call_host(
    grpc_exec_ctx *exec_ctx, grpc_channel_security_connector *sc,
    grpc_closure *on_call_host_checked, grpc_error *error);

/* Registers handshakers with \a handshake_mgr. */
void grpc_channel_security_connector_add_handshakers(
    grpc_exec_ctx *exec_ctx, grpc_channel_security_connector *connector,
    grpc_handshake_manager *handshake_mgr);

/* --- server_security_connector object. ---

    A server security connector object represents away to configure the
    underlying transport security mechanism on the server side.  */

typedef struct grpc_server_security_connector grpc_server_security_connector;

struct grpc_server_security_connector {
  grpc_security_connector base;
  void (*add_handshakers)(grpc_exec_ctx *exec_ctx,
                          grpc_server_security_connector *sc,
                          grpc_handshake_manager *handshake_mgr);
};

void grpc_server_security_connector_add_handshakers(
    grpc_exec_ctx *exec_ctx, grpc_server_security_connector *sc,
    grpc_handshake_manager *handshake_mgr);

/* --- Creation security connectors. --- */

/* For TESTING ONLY!
   Creates a fake connector that emulates real channel security.  */
grpc_channel_security_connector *grpc_fake_channel_security_connector_create(
    grpc_call_credentials *request_metadata_creds, const char *target,
    const grpc_channel_args *args);

/* For TESTING ONLY!
   Creates a fake connector that emulates real server security.  */
grpc_server_security_connector *grpc_fake_server_security_connector_create(
    void);

/* Config for ssl clients. */

typedef struct {
  tsi_ssl_pem_key_cert_pair pem_key_cert_pair;
  char *pem_root_certs;
} grpc_ssl_config;

/* Creates an SSL channel_security_connector.
   - request_metadata_creds is the credentials object which metadata
     will be sent with each request. This parameter can be NULL.
   - config is the SSL config to be used for the SSL channel establishment.
   - is_client should be 0 for a server or a non-0 value for a client.
   - secure_peer_name is the secure peer name that should be checked in
     grpc_channel_security_connector_check_peer. This parameter may be NULL in
     which case the peer name will not be checked. Note that if this parameter
     is not NULL, then, pem_root_certs should not be NULL either.
   - sc is a pointer on the connector to be created.
  This function returns GRPC_SECURITY_OK in case of success or a
  specific error code otherwise.
*/
grpc_security_status grpc_ssl_channel_security_connector_create(
    grpc_exec_ctx *exec_ctx, grpc_call_credentials *request_metadata_creds,
    const grpc_ssl_config *config, const char *target_name,
    const char *overridden_target_name, grpc_channel_security_connector **sc);

/* Gets the default ssl roots. Returns NULL if not found. */
const char *grpc_get_default_ssl_roots(void);

/* Exposed for TESTING ONLY!. */
grpc_slice grpc_get_default_ssl_roots_for_testing(void);

/* Config for ssl servers. */
typedef struct {
  tsi_ssl_pem_key_cert_pair *pem_key_cert_pairs;
  size_t num_key_cert_pairs;
  char *pem_root_certs;
  grpc_ssl_client_certificate_request_type client_certificate_request;
} grpc_ssl_server_config;

/* Creates an SSL server_security_connector.
   - config is the SSL config to be used for the SSL channel establishment.
   - sc is a pointer on the connector to be created.
  This function returns GRPC_SECURITY_OK in case of success or a
  specific error code otherwise.
*/
grpc_security_status grpc_ssl_server_security_connector_create(
    grpc_exec_ctx *exec_ctx, const grpc_ssl_server_config *config,
    grpc_server_security_connector **sc);

/* Util. */
const tsi_peer_property *tsi_peer_get_property_by_name(const tsi_peer *peer,
                                                       const char *name);

/* Exposed for testing only. */
grpc_auth_context *tsi_ssl_peer_to_auth_context(const tsi_peer *peer);
tsi_peer tsi_shallow_peer_from_ssl_auth_context(
    const grpc_auth_context *auth_context);
void tsi_shallow_peer_destruct(tsi_peer *peer);

#endif /* GRPC_CORE_LIB_SECURITY_TRANSPORT_SECURITY_CONNECTOR_H */
