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gnrc_ipv6_nib: expose non-randomized part of NS-backoff calculation

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This was primarily done so the backoff can be tested
This commit is contained in:
Martine Lenders 2019-01-29 13:25:59 +01:00
parent 1f4d57d608
commit 82001cfd79
2 changed files with 40 additions and 11 deletions
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14
sys/net/gnrc/network_layer/ipv6/nib/_nib-arsm.c
View File

@ -514,18 +514,10 @@ bool _is_reachable(_nib_onl_entry_t *entry)
static inline uint32_t _exp_backoff_retrans_timer(uint8_t ns_sent,
uint32_t retrans_timer)
{
uint32_t tmp = random_uint32_range(NDP_MIN_RANDOM_FACTOR,
NDP_MAX_RANDOM_FACTOR);
uint32_t factor = random_uint32_range(NDP_MIN_RANDOM_FACTOR,
NDP_MAX_RANDOM_FACTOR);
/* backoff according to https://tools.ietf.org/html/rfc7048 with
* BACKOFF_MULTIPLE == 2 */
tmp = (uint32_t)(((uint64_t)(((uint32_t) 1) << ns_sent) * retrans_timer *
tmp) / US_PER_MS);
/* random factors were statically multiplied with 1000 ^ */
if (tmp > NDP_MAX_RETRANS_TIMER_MS) {
tmp = NDP_MAX_RETRANS_TIMER_MS;
}
return tmp;
return _exp_backoff_retrans_timer_factor(ns_sent, retrans_timer, factor);
}
#if GNRC_IPV6_NIB_CONF_REDIRECT

37
sys/net/gnrc/network_layer/ipv6/nib/_nib-arsm.h
View File

@ -81,6 +81,43 @@ void _snd_uc_ns(_nib_onl_entry_t *nbr, bool reset);
void _handle_sl2ao(gnrc_netif_t *netif, const ipv6_hdr_t *ipv6,
const icmpv6_hdr_t *icmpv6, const ndp_opt_t *sl2ao);
/**
* @brief Calculates truncated exponential back-off for retransmission timer
* for neighbor solicitations based on a randomized factor
*
* The truncation is at @ref NDP_MAX_RETRANS_TIMER_MS. as suggested in
* [RFC 7048, section 3](https://tools.ietf.org/html/rfc7048#section-3).
*
* @param[in] ns_sent Neighbor solicitations sent up until now. Must be
* lesser than or equal to @ref NDP_MAX_NS_NUMOF.
* @param[in] retrans_timer Currently configured retransmission timer in ms.
* @param[in] factor An equally distributed factor between
* @ref NDP_MIN_RANDOM_FACTOR and (exclusive)
* @ref NDP_MAX_RANDOM_FACTOR.
*
* @pre (NDP_MIN_RANDOM_FACTOR <= factor < NDP_MAX_RANDOM_FACTOR)
* @pre (ns_sent <= NDP_MAX_NS_NUMOF)
*
* @return exponential back-off of the retransmission timer
*/
static inline uint32_t _exp_backoff_retrans_timer_factor(uint8_t ns_sent,
uint32_t retrans_timer,
uint32_t factor)
{
assert(NDP_MIN_RANDOM_FACTOR <= factor);
assert(factor < NDP_MAX_RANDOM_FACTOR);
assert(ns_sent <= NDP_MAX_NS_NUMOF);
/* backoff according to https://tools.ietf.org/html/rfc7048 with
* BACKOFF_MULTIPLE == 2 */
uint32_t res = (uint32_t)(((uint64_t)(((uint32_t) 1) << ns_sent) *
retrans_timer * factor) / US_PER_MS);
/* random factors were statically multiplied with 1000 */
if (res > NDP_MAX_RETRANS_TIMER_MS) {
res = NDP_MAX_RETRANS_TIMER_MS;
}
return res;
}
#if GNRC_IPV6_NIB_CONF_ARSM || defined(DOXYGEN)
/**
* @brief Handler for @ref GNRC_IPV6_NIB_SND_UC_NS and