nat64-6lowpan.h

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/*
 * Copyright (c) 2026, RISE Research Institutes of Sweden AB.
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/**
 * \addtogroup nat64
 * @{
 *
 * \file
 *         6LoWPAN compression context for the NAT64 prefix.
 *
 *         Registers the upper 64 bits of the NAT64 prefix as IPHC
 *         context 1, saving ~8 header bytes per NAT64-bound packet.
 *         Must be included from project-conf.h on both the border
 *         router and every IoT node sending NAT64 traffic; the two
 *         sides must agree on prefix and context number, otherwise
 *         frames silently fail to decompress.
 *
 *         TODO: replace with runtime distribution once Contiki-NG
 *         implements RFC 6775 §4.2 (6CO option in RAs).
 *
 * \author
 *         Nicolas Tsiftes <nicolas.tsiftes@ri.se>
 */
 
#ifndef NAT64_6LOWPAN_H_
#define NAT64_6LOWPAN_H_
 
/**
 * \brief Upper 64 bits of the NAT64 prefix as 8 bytes.
 *
 * Defaults to the well-known `64:ff9b::/96` (RFC 6052). Override
 * only for a non-standard prefix; both ends must match.
 */
#ifndef NAT64_6LOWPAN_PREFIX_BYTES
#define NAT64_6LOWPAN_PREFIX_BYTES 0x00, 0x64, 0xff, 0x9b, \
                                   0x00, 0x00, 0x00, 0x00
#endif
 
/* Reserve slot 0 for the network prefix and slot 1 for NAT64. */
#ifndef SICSLOWPAN_CONF_MAX_ADDR_CONTEXTS
#define SICSLOWPAN_CONF_MAX_ADDR_CONTEXTS 2
#elif SICSLOWPAN_CONF_MAX_ADDR_CONTEXTS < 2
#error "NAT64 6LoWPAN context requires SICSLOWPAN_CONF_MAX_ADDR_CONTEXTS >= 2"
#endif
 
/* Install the NAT64 prefix into context slot 1 from sicslowpan_init().
 * Only the upper 64 bits are elided; the embedded IPv4 in the lower
 * 64 bits is carried inline via IPHC SAM=01 (8 bytes). */
#define SICSLOWPAN_CONF_ADDR_CONTEXT_1                                 \
  do {                                                                 \
    static const uint8_t nat64_ctx_prefix[8] = {                       \
      NAT64_6LOWPAN_PREFIX_BYTES                                       \
    };                                                                 \
    memcpy(addr_contexts[1].prefix, nat64_ctx_prefix, 8);              \
  } while(0)
 
/** @} */
 
#endif /* NAT64_6LOWPAN_H_ */