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RIOT/sys/include/net/gnrc/sixlowpan/ctx.h 4 KB
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  /*
   * Copyright (C) 2015 Martine Lenders <mlenders@inf.fu-berlin.de>
   *
   * This file is subject to the terms and conditions of the GNU Lesser
   * General Public License v2.1. See the file LICENSE in the top level
   * directory for more details.
   */
  
  /**
   * @defgroup    net_gnrc_sixlowpan_ctx    Contexts for 6LoWPAN address compression
   * @ingroup     net_gnrc_sixlowpan
   * @brief       Context buffer for stateful 6LoWPAN address compression
   * @see         <a href="https://tools.ietf.org/html/rfc6282#section-3.1.2">
   *                  RFC 6282, section 3.1.2
   *              </a>
   * @see         <a href="http://tools.ietf.org/html/rfc6775#section-4.2">
   *                  RFC 6775, section 4.2
   *              </a>
   * @{
   *
   * @file
   * @brief   Context buffer definitions
   *
   * @author  Martine Lenders <mlenders@inf.fu-berlin.de>
   */
  #ifndef GNRC_SIXLOWPAN_CTX_H_
  #define GNRC_SIXLOWPAN_CTX_H_
  
  #include <inttypes.h>
  #include <stdbool.h>
  
  #include "net/ipv6/addr.h"
  
  #ifdef __cplusplus
  extern "C" {
  #endif
  
  #define GNRC_SIXLOWPAN_CTX_SIZE (16)    /**< maximum number of entries in
                                           *   context buffer */
  
  /**
   * @{
   * @name    Context flags.
   * @brief   Flags to set in gnrc_sixlowpan_ctx_t::flags_id.
   */
  #define GNRC_SIXLOWPAN_CTX_FLAGS_CID_MASK   (0x0f)  /**< mask for the Context ID. */
  #define GNRC_SIXLOWPAN_CTX_FLAGS_COMP       (0x10)  /**< Use context for compression */
  /**
   * @}
   */
  
  /**
   * @brief   Entry in the 6LoWPAN context buffer.
   */
  typedef struct {
      ipv6_addr_t prefix;     /**< The prefix associated to this context. */
      uint8_t prefix_len;     /**< Length of gnrc_sixlowpan_ctx_t::prefix in bit. */
      /**
       * @brief   4-bit flags, 4-bit Context ID.
       *
       * @note    This needs to be here to easily translate prefixes to
       *          ID.
       *
       * @details The flags are defined as above.
       */
      uint8_t flags_id;
      /**
       * @brief   Lifetime in minutes this context is valid.
       *
       * @see     <a href="http://tools.ietf.org/html/rfc6775#section-4.2">
       *              6LoWPAN Context Option
       *          </a>
       */
      uint16_t ltime;
  } gnrc_sixlowpan_ctx_t;
  
  /**
   * @brief   Gets a context matching the given IPv6 address best with its prefix.
   *
   * @param[in] addr  An IPv6 address.
   *
   * @return  The context associated with the best prefix for @p addr.
   * @return  NULL if there is no such context.
   */
  gnrc_sixlowpan_ctx_t *gnrc_sixlowpan_ctx_lookup_addr(const ipv6_addr_t *addr);
  
  /**
   * @brief   Gets context by ID.
   *
   * @param[in] id    A context ID.
   *
   * @return  The context associated with @p id.
   * @return  NULL if there is no such context.
   */
  gnrc_sixlowpan_ctx_t *gnrc_sixlowpan_ctx_lookup_id(uint8_t id);
  
  /**
   * @brief   Updates (or adds if currently not registered) a context
   *
   * @param[in] id            The ID for the context.
   *                          Must be < @ref GNRC_SIXLOWPAN_CTX_SIZE.
   * @param[in] prefix        The prefix for the context.
   * @param[in] prefix_len    Length of @p prefix in bits. Must be > 0.
   * @param[in] ltime         New lifetime of the context. @p comp will be
   *                          implicitly set to `false` if @p ltime == 0.
   * @param[in] comp          Use for compression if true, do not use for
   *                          compression, but still for decompression if false.
   *
   * @return  The new context on success.
   * @return  NULL, on error or on removal.
   */
  gnrc_sixlowpan_ctx_t *gnrc_sixlowpan_ctx_update(uint8_t id, const ipv6_addr_t *prefix,
                                                  uint8_t prefix_len, uint16_t ltime,
                                                  bool comp);
  
  #ifdef MODULE_GNRC_SIXLOWPAN_CTX
  /**
   * @brief   Removes context.
   *
   * @param[in] id    A context ID.
   */
  static inline void gnrc_sixlowpan_ctx_remove(uint8_t id)
  {
      gnrc_sixlowpan_ctx_lookup_id(id)->prefix_len = 0;
  }
  #endif
  
  #ifdef TEST_SUITES
  /**
   * @brief   Resets the whole context buffer.
   */
  void gnrc_sixlowpan_ctx_reset(void);
  #endif
  
  #ifdef __cplusplus
  }
  #endif
  
  #endif /* GNRC_SIXLOWPAN_CTX_H_ */
  /** @} */