// Copyright 2018 Google Inc. All Rights Reserved.
//
// 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.

// Adapted from http/http_auth_gssapi_posix.h

#ifndef NET_HTTP_HTTP_AUTH_GSSAPI_STARBOARD_H_
#define NET_HTTP_HTTP_AUTH_GSSAPI_STARBOARD_H_

#include <string>

#include "starboard/types.h"

#include "base/gtest_prod_util.h"
#include "base/macros.h"
#include "base/native_library.h"
#include "net/base/completion_once_callback.h"
#include "net/base/net_export.h"
#include "net/http/http_auth.h"

#if defined(OS_MACOSX)
#include <GSS/gssapi.h>
#elif defined(OS_FREEBSD)
#include <gssapi/gssapi.h>
#else
#include <gssapi.h>
#endif

namespace net {

class HttpAuthChallengeTokenizer;

// Mechanism OID for GSSAPI. We always use SPNEGO.
NET_EXPORT_PRIVATE extern gss_OID CHROME_GSS_SPNEGO_MECH_OID_DESC;

// GSSAPILibrary is introduced so unit tests can mock the calls to the GSSAPI
// library. The default implementation attempts to load one of the standard
// GSSAPI library implementations, then simply passes the arguments on to
// that implementation.
class NET_EXPORT_PRIVATE GSSAPILibrary {
 public:
  virtual ~GSSAPILibrary() {}

  // Initializes the library, including any necessary dynamic libraries.
  // This is done separately from construction (which happens at startup time)
  // in order to delay work until the class is actually needed.
  virtual bool Init() = 0;

  // These methods match the ones in the GSSAPI library.
  virtual OM_uint32 import_name(OM_uint32* minor_status,
                                const gss_buffer_t input_name_buffer,
                                const gss_OID input_name_type,
                                gss_name_t* output_name) = 0;
  virtual OM_uint32 release_name(OM_uint32* minor_status,
                                 gss_name_t* input_name) = 0;
  virtual OM_uint32 release_buffer(OM_uint32* minor_status,
                                   gss_buffer_t buffer) = 0;
  virtual OM_uint32 display_name(OM_uint32* minor_status,
                                 const gss_name_t input_name,
                                 gss_buffer_t output_name_buffer,
                                 gss_OID* output_name_type) = 0;
  virtual OM_uint32 display_status(OM_uint32* minor_status,
                                   OM_uint32 status_value,
                                   int status_type,
                                   const gss_OID mech_type,
                                   OM_uint32* message_contex,
                                   gss_buffer_t status_string) = 0;
  virtual OM_uint32 init_sec_context(
      OM_uint32* minor_status,
      const gss_cred_id_t initiator_cred_handle,
      gss_ctx_id_t* context_handle,
      const gss_name_t target_name,
      const gss_OID mech_type,
      OM_uint32 req_flags,
      OM_uint32 time_req,
      const gss_channel_bindings_t input_chan_bindings,
      const gss_buffer_t input_token,
      gss_OID* actual_mech_type,
      gss_buffer_t output_token,
      OM_uint32* ret_flags,
      OM_uint32* time_rec) = 0;
  virtual OM_uint32 wrap_size_limit(OM_uint32* minor_status,
                                    const gss_ctx_id_t context_handle,
                                    int conf_req_flag,
                                    gss_qop_t qop_req,
                                    OM_uint32 req_output_size,
                                    OM_uint32* max_input_size) = 0;
  virtual OM_uint32 delete_sec_context(OM_uint32* minor_status,
                                       gss_ctx_id_t* context_handle,
                                       gss_buffer_t output_token) = 0;
  virtual OM_uint32 inquire_context(OM_uint32* minor_status,
                                    const gss_ctx_id_t context_handle,
                                    gss_name_t* src_name,
                                    gss_name_t* targ_name,
                                    OM_uint32* lifetime_rec,
                                    gss_OID* mech_type,
                                    OM_uint32* ctx_flags,
                                    int* locally_initiated,
                                    int* open) = 0;
  virtual const std::string& GetLibraryNameForTesting() = 0;
};

// GSSAPISharedLibrary class is defined here so that unit tests can access it.
class NET_EXPORT_PRIVATE GSSAPISharedLibrary : public GSSAPILibrary {
 public:
  // If |gssapi_library_name| is empty, hard-coded default library names are
  // used.
  explicit GSSAPISharedLibrary(const std::string& gssapi_library_name);

  // GSSAPILibrary methods:
  bool Init() override;
  OM_uint32 import_name(OM_uint32* minor_status,
                        const gss_buffer_t input_name_buffer,
                        const gss_OID input_name_type,
                        gss_name_t* output_name) override;
  OM_uint32 release_name(OM_uint32* minor_status,
                         gss_name_t* input_name) override;
  OM_uint32 release_buffer(OM_uint32* minor_status,
                           gss_buffer_t buffer) override;
  OM_uint32 display_name(OM_uint32* minor_status,
                         const gss_name_t input_name,
                         gss_buffer_t output_name_buffer,
                         gss_OID* output_name_type) override;
  OM_uint32 display_status(OM_uint32* minor_status,
                           OM_uint32 status_value,
                           int status_type,
                           const gss_OID mech_type,
                           OM_uint32* message_contex,
                           gss_buffer_t status_string) override;
  OM_uint32 init_sec_context(OM_uint32* minor_status,
                             const gss_cred_id_t initiator_cred_handle,
                             gss_ctx_id_t* context_handle,
                             const gss_name_t target_name,
                             const gss_OID mech_type,
                             OM_uint32 req_flags,
                             OM_uint32 time_req,
                             const gss_channel_bindings_t input_chan_bindings,
                             const gss_buffer_t input_token,
                             gss_OID* actual_mech_type,
                             gss_buffer_t output_token,
                             OM_uint32* ret_flags,
                             OM_uint32* time_rec) override;
  OM_uint32 wrap_size_limit(OM_uint32* minor_status,
                            const gss_ctx_id_t context_handle,
                            int conf_req_flag,
                            gss_qop_t qop_req,
                            OM_uint32 req_output_size,
                            OM_uint32* max_input_size) override;
  OM_uint32 delete_sec_context(OM_uint32* minor_status,
                               gss_ctx_id_t* context_handle,
                               gss_buffer_t output_token) override;
  OM_uint32 inquire_context(OM_uint32* minor_status,
                            const gss_ctx_id_t context_handle,
                            gss_name_t* src_name,
                            gss_name_t* targ_name,
                            OM_uint32* lifetime_rec,
                            gss_OID* mech_type,
                            OM_uint32* ctx_flags,
                            int* locally_initiated,
                            int* open) override;
  const std::string& GetLibraryNameForTesting() override;

 private:
  typedef decltype(&gss_import_name) gss_import_name_type;
  typedef decltype(&gss_release_name) gss_release_name_type;
  typedef decltype(&gss_release_buffer) gss_release_buffer_type;
  typedef decltype(&gss_display_name) gss_display_name_type;
  typedef decltype(&gss_display_status) gss_display_status_type;
  typedef decltype(&gss_init_sec_context) gss_init_sec_context_type;
  typedef decltype(&gss_wrap_size_limit) gss_wrap_size_limit_type;
  typedef decltype(&gss_delete_sec_context) gss_delete_sec_context_type;
  typedef decltype(&gss_inquire_context) gss_inquire_context_type;

  FRIEND_TEST_ALL_PREFIXES(HttpAuthGSSAPISTARBOARDTest, GSSAPIStartup);

  bool InitImpl();

  bool initialized_;

  std::string gssapi_library_name_;

  // Function pointers
  gss_import_name_type import_name_;
  gss_release_name_type release_name_;
  gss_release_buffer_type release_buffer_;
  gss_display_name_type display_name_;
  gss_display_status_type display_status_;
  gss_init_sec_context_type init_sec_context_;
  gss_wrap_size_limit_type wrap_size_limit_;
  gss_delete_sec_context_type delete_sec_context_;
  gss_inquire_context_type inquire_context_;
};

// ScopedSecurityContext releases a gss_ctx_id_t when it goes out of
// scope.
class ScopedSecurityContext {
 public:
  explicit ScopedSecurityContext(GSSAPILibrary* gssapi_lib);
  ~ScopedSecurityContext();

  gss_ctx_id_t get() const { return security_context_; }
  gss_ctx_id_t* receive() { return &security_context_; }

 private:
  gss_ctx_id_t security_context_;
  GSSAPILibrary* gssapi_lib_;

  DISALLOW_COPY_AND_ASSIGN(ScopedSecurityContext);
};

// TODO(ahendrickson): Share code with HttpAuthSSPI.
class NET_EXPORT_PRIVATE HttpAuthGSSAPI {
 public:
  HttpAuthGSSAPI(GSSAPILibrary* library,
                 const std::string& scheme,
                 const gss_OID gss_oid);
  ~HttpAuthGSSAPI();

  bool Init();

  bool NeedsIdentity() const;

  bool AllowsExplicitCredentials() const;

  HttpAuth::AuthorizationResult ParseChallenge(HttpAuthChallengeTokenizer* tok);

  // Generates an authentication token.
  //
  // The return value is an error code. The authentication token will be
  // returned in |*auth_token|. If the result code is not |OK|, the value of
  // |*auth_token| is unspecified.
  //
  // If the operation cannot be completed synchronously, |ERR_IO_PENDING| will
  // be returned and the real result code will be passed to the completion
  // callback.  Otherwise the result code is returned immediately from this
  // call.
  //
  // If the HttpAuthGSSAPI object is deleted before completion then the callback
  // will not be called.
  //
  // If no immediate result is returned then |auth_token| must remain valid
  // until the callback has been called.
  //
  // |spn| is the Service Principal Name of the server that the token is
  // being generated for.
  //
  // If this is the first round of a multiple round scheme, credentials are
  // obtained using |*credentials|. If |credentials| is NULL, the default
  // credentials are used instead.
  int GenerateAuthToken(const AuthCredentials* credentials,
                        const std::string& spn,
                        const std::string& channel_bindings,
                        std::string* auth_token,
                        CompletionOnceCallback callback);

  // Delegation is allowed on the Kerberos ticket. This allows certain servers
  // to act as the user, such as an IIS server retrieving data from a
  // Kerberized MSSQL server.
  void Delegate();

 private:
  int GetNextSecurityToken(const std::string& spn,
                           const std::string& channel_bindings,
                           gss_buffer_t in_token,
                           gss_buffer_t out_token);

  std::string scheme_;
  gss_OID gss_oid_;
  GSSAPILibrary* library_;
  std::string decoded_server_auth_token_;
  ScopedSecurityContext scoped_sec_context_;
  bool can_delegate_;
};

}  // namespace net

#endif  // NET_HTTP_HTTP_AUTH_GSSAPI_STARBOARD_H_