text: /*
   * Copyright (c) 2009, 2010, 2012, 2013, 2015 Nicira, Inc.
   *
   * 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 STREAM_PROVIDER_H
  #define STREAM_PROVIDER_H 1
  
  #include <sys/types.h>
  #include "ovs-replay.h"
  #include "stream.h"
  
  /* Active stream connection. */
  
  /* Active stream connection.
   *
   * This structure should be treated as opaque by implementation. */
  struct stream {
      const struct stream_class *class;/*fd使用stream_fd_class，*/
      int state;
      int error;
      replay_file_t replay_wfd;
      char *name;
      char *peer_id;
  };
  
  void stream_init(struct stream *, const struct stream_class *,
                   int connect_status, char *name);
  static inline void stream_assert_class(const struct stream *stream,
                                         const struct stream_class *class)
  {
      ovs_assert(stream->class == class);
  }
  
  struct stream_class {
      /* Prefix for connection names, e.g. "tcp", "ssl", "unix". */
      const char *name;
  
      /* True if this stream needs periodic probes to verify connectivity.  For
       * streams which need probes, it can take a long time to notice the
       * connection was dropped. */
      bool needs_probes;
  
      /* Attempts to connect to a peer.  'name' is the full connection name
       * provided by the user, e.g. "tcp:1.2.3.4".  This name is useful for error
       * messages but must not be modified.
       *
       * 'suffix' is a copy of 'name' following the colon and may be modified.
       * 'dscp' is the DSCP value that the new connection should use in the IP
       * packets it sends.
       *
       * Returns 0 if successful, otherwise a positive errno value.  If
       * successful, stores a pointer to the new connection in '*streamp'.
       *
       * The open function must not block waiting for a connection to complete.
       * If the connection cannot be completed immediately, it should return
       * EAGAIN (not EINPROGRESS, as returned by the connect system call) and
       * continue the connection in the background. */
      int (*open)(const char *name, char *suffix, struct stream **streamp,
                  uint8_t dscp);
  
      /* Closes 'stream' and frees associated memory. */
      void (*close)(struct stream *stream);
  
      /* Tries to complete the connection on 'stream'.  If 'stream''s connection
       * is complete, returns 0 if the connection was successful or a positive
       * errno value if it failed.  If the connection is still in progress,
       * returns EAGAIN.
       *
       * The connect function must not block waiting for the connection to
       * complete; instead, it should return EAGAIN immediately. */
      int (*connect)(struct stream *stream);
  
      /* Tries to receive up to 'n' bytes from 'stream' into 'buffer', and
       * returns:
       *
       *     - If successful, the number of bytes received (between 1 and 'n').
       *
       *     - On error, a negative errno value.
       *
       *     - 0, if the connection has been closed in the normal fashion.
       *
       * The recv function will not be passed a zero 'n'.
       *
       * The recv function must not block waiting for data to arrive.  If no data
       * have been received, it should return -EAGAIN immediately. */
      ssize_t (*recv)(struct stream *stream, void *buffer, size_t n);
  
      /* Tries to send up to 'n' bytes of 'buffer' on 'stream', and returns:
       *
       *     - If successful, the number of bytes sent (between 1 and 'n').
       *
       *     - On error, a negative errno value.
       *
       *     - Never returns 0.
       *
       * The send function will not be passed a zero 'n'.
       *
       * The send function must not block.  If no bytes can be immediately
       * accepted for transmission, it should return -EAGAIN immediately. */
      ssize_t (*send)(struct stream *stream, const void *buffer, size_t n);
  
      /* Allows 'stream' to perform maintenance activities, such as flushing
       * output buffers.
       *
       * May be null if 'stream' doesn't have anything to do here. */
      void (*run)(struct stream *stream);
  
      /* Arranges for the poll loop to wake up when 'stream' needs to perform
       * maintenance activities.
       *
       * May be null if 'stream' doesn't have anything to do here. */
      void (*run_wait)(struct stream *stream);
  
      /* Arranges for the poll loop to wake up when 'stream' is ready to take an
       * action of the given 'type'. */
      void (*wait)(struct stream *stream, enum stream_wait_type type);
  };
  
  /* Passive listener for incoming stream connections.
   *
   * This structure should be treated as opaque by stream implementations. */
  struct pstream {
      const struct pstream_class *class;//对应的class
      char *name;//对应的名称
      ovs_be16 bound_port;
      replay_file_t replay_wfd;
  };
  
  void pstream_init(struct pstream *, const struct pstream_class *, char *name);
  void pstream_set_bound_port(struct pstream *, ovs_be16 bound_port);
  static inline void pstream_assert_class(const struct pstream *pstream,
                                          const struct pstream_class *class)
  {
      ovs_assert(pstream->class == class);
  }
  
  //服务器端class
  struct pstream_class {
      /* Prefix for connection names, e.g. "ptcp", "pssl", "punix". */
      const char *name;
  
      /* True if this pstream needs periodic probes to verify connectivity.  For
       * pstreams which need probes, it can take a long time to notice the
       * connection was dropped. */
      bool needs_probes;
  
      /* Attempts to start listening for stream connections.  'name' is the full
       * connection name provided by the user, e.g. "ptcp:1234".  This name is
       * useful for error messages but must not be modified.
       *
       * 'suffix' is a copy of 'name' following the colon and may be modified.
       * 'dscp' is the DSCP value that the new connection should use in the IP
       * packets it sends.
       *
       * Returns 0 if successful, otherwise a positive errno value.  If
       * successful, stores a pointer to the new connection in '*pstreamp'.
       *
       * The listen function must not block.  If the connection cannot be
       * completed immediately, it should return EAGAIN (not EINPROGRESS, as
       * returned by the connect system call) and continue the connection in the
       * background. */
      int (*listen)(const char *name, char *suffix, struct pstream **pstreamp,
                    uint8_t dscp);
  
      /* Closes 'pstream' and frees associated memory. */
      void (*close)(struct pstream *pstream);
  
      /* Tries to accept a new connection on 'pstream'.  If successful, stores
       * the new connection in '*new_streamp' and returns 0.  Otherwise, returns
       * a positive errno value.
       *
       * The accept function must not block waiting for a connection.  If no
       * connection is ready to be accepted, it should return EAGAIN. */
      int (*accept)(struct pstream *pstream, struct stream **new_streamp);
  
      /* Arranges for the poll loop to wake up when a connection is ready to be
       * accepted on 'pstream'. */
      void (*wait)(struct pstream *pstream);
  };
  
  /* Active and passive stream classes. */
  extern const struct stream_class tcp_stream_class;
  extern const struct pstream_class ptcp_pstream_class;
  #ifndef _WIN32
  extern const struct stream_class unix_stream_class;
  extern const struct pstream_class punix_pstream_class;
  #else
  extern const struct stream_class windows_stream_class;
  extern const struct pstream_class pwindows_pstream_class;
  #endif
  #ifdef HAVE_OPENSSL
  extern const struct stream_class ssl_stream_class;
  extern const struct pstream_class pssl_pstream_class;
  #endif
  extern const struct stream_class replay_stream_class;
  extern const struct pstream_class preplay_pstream_class;
  
  #endif /* stream-provider.h */
  