text: /*
   * Copyright (c) 2008 Nicira Networks.
   *
   * 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 STP_H
  #define STP_H 1
  
  /* This is an implementation of Spanning Tree Protocol as described in IEEE
   * 802.1D-1998, clauses 8 and 9.  Section numbers refer to this standard.  */
  
  #include <stdbool.h>
  #include <stdint.h>
  #include "compiler.h"
  #include "util.h"
  
  struct ofpbuf;
  
  /* Ethernet address used as the destination for STP frames. */
  extern const uint8_t stp_eth_addr[6];
  
  /* LLC field values used for STP frames. */
  #define STP_LLC_SSAP 0x42
  #define STP_LLC_DSAP 0x42
  #define STP_LLC_CNTL 0x03
  
  /* Bridge and port priorities that should be used by default. */
  #define STP_DEFAULT_BRIDGE_PRIORITY 32768
  #define STP_DEFAULT_PORT_PRIORITY 128
  
  /* Bridge identifier.  Top 16 bits are a priority value (numerically lower
   * values are higher priorities).  Bottom 48 bits are MAC address of bridge. */
  typedef uint64_t stp_identifier;
  
  /* Basic STP functionality. */
  #define STP_MAX_PORTS 255
  struct stp *stp_create(const char *name, stp_identifier bridge_id,
                         void (*send_bpdu)(struct ofpbuf *bpdu, int port_no,
                                           void *aux),
                         void *aux);
  void stp_destroy(struct stp *);
  void stp_tick(struct stp *, int ms);
  void stp_set_bridge_id(struct stp *, stp_identifier bridge_id);
  void stp_set_bridge_priority(struct stp *, uint16_t new_priority);
  void stp_set_hello_time(struct stp *, int ms);
  void stp_set_max_age(struct stp *, int ms);
  void stp_set_forward_delay(struct stp *, int ms);
  
  /* STP properties. */
  const char *stp_get_name(const struct stp *);
  stp_identifier stp_get_bridge_id(const struct stp *);
  stp_identifier stp_get_designated_root(const struct stp *);
  bool stp_is_root_bridge(const struct stp *);
  int stp_get_root_path_cost(const struct stp *);
  int stp_get_hello_time(const struct stp *);
  int stp_get_max_age(const struct stp *);
  int stp_get_forward_delay(const struct stp *);
  
  /* Obtaining STP ports. */
  struct stp_port *stp_get_port(struct stp *, int port_no);
  struct stp_port *stp_get_root_port(struct stp *);
  bool stp_get_changed_port(struct stp *, struct stp_port **portp);
  
  /* State of an STP port.
   *
   * A port is in exactly one state at any given time, but distinct bits are used
   * for states to allow testing for more than one state with a bit mask. */
  enum stp_state {
      STP_DISABLED = 1 << 0,       /* 8.4.5: Disabled by management. */
      STP_LISTENING = 1 << 1,      /* 8.4.2: Not learning or relaying frames. */
      STP_LEARNING = 1 << 2,       /* 8.4.3: Learning but not relaying frames. */
      STP_FORWARDING = 1 << 3,     /* 8.4.4: Learning and relaying frames. */
      STP_BLOCKING = 1 << 4        /* 8.4.1: Initial boot state. */
  };
  const char *stp_state_name(enum stp_state);
  bool stp_forward_in_state(enum stp_state);
  bool stp_learn_in_state(enum stp_state);
  
  void stp_received_bpdu(struct stp_port *, const void *bpdu, size_t bpdu_size);
  
  struct stp *stp_port_get_stp(struct stp_port *);
  int stp_port_no(const struct stp_port *);
  enum stp_state stp_port_get_state(const struct stp_port *);
  void stp_port_enable(struct stp_port *);
  void stp_port_disable(struct stp_port *);
  void stp_port_set_priority(struct stp_port *, uint8_t new_priority);
  void stp_port_set_path_cost(struct stp_port *, uint16_t path_cost);
  void stp_port_set_speed(struct stp_port *, unsigned int speed);
  void stp_port_enable_change_detection(struct stp_port *);
  void stp_port_disable_change_detection(struct stp_port *);
  
  #endif /* stp.h */
  