static unsigned eval_addr_set(pack_t *addr_set, kr_nsrep_lru_t *rttcache, unsigned score, uint8_t *addr[], uint32_t opts)
{
/* Name server is better candidate if it has address record. */
uint8_t *it = pack_head(*addr_set);
while (it != pack_tail(*addr_set)) {
void *val = pack_obj_val(it);
size_t len = pack_obj_len(it);
unsigned favour = 0;
bool is_valid = false;
/* Check if the address isn't disabled. */
if (len == sizeof(struct in6_addr)) {
is_valid = !(opts & QUERY_NO_IPV6);
favour = FAVOUR_IPV6;
} else {
is_valid = !(opts & QUERY_NO_IPV4);
}
/* Get RTT for this address (if known) */
if (is_valid) {
unsigned *cached = rttcache ? lru_get(rttcache, val, len) : NULL;
unsigned addr_score = (cached) ? *cached : KR_NS_GLUED;
if (addr_score < score + favour) {
/* Shake down previous contenders */
for (size_t i = KR_NSREP_MAXADDR - 1; i > 0; --i)
addr[i] = addr[i - 1];
addr[0] = it;
score = addr_score;
}
}
it = pack_obj_next(it);
}
return score;
}
static int eval_nsrep(const char *k, void *v, void *baton)
{
struct kr_query *qry = baton;
struct kr_nsrep *ns = &qry->ns;
struct kr_context *ctx = ns->ctx;
unsigned score = KR_NS_MAX_SCORE;
unsigned reputation = 0;
uint8_t *addr = NULL;
/* Fetch NS reputation */
if (ctx->cache_rep) {
unsigned *cached = lru_get(ctx->cache_rep, k, knot_dname_size((const uint8_t *)k));
if (cached) {
reputation = *cached;
}
}
/* Favour nameservers with unknown addresses to probe them,
* otherwise discover the current best address for the NS. */
pack_t *addr_set = (pack_t *)v;
if (addr_set->len == 0) {
score = KR_NS_UNKNOWN;
/* If the server doesn't have IPv6, give it disadvantage. */
if (reputation & KR_NS_NOIP6) {
score += FAVOUR_IPV6;
/* If the server is unknown but has rep record, treat it as timeouted */
if (reputation & KR_NS_NOIP4) {
score = KR_NS_TIMEOUT;
reputation = 0; /* Start with clean slate */
}
}
} else {
score = eval_addr_set(addr_set, ctx->cache_rtt, score, &addr);
}
/* Probabilistic bee foraging strategy (naive).
* The fastest NS is preferred by workers until it is depleted (timeouts or degrades),
* at the same time long distance scouts probe other sources (low probability).
* Servers on TIMEOUT (depleted) can be probed by the dice roll only */
if (score < ns->score && (qry->flags & QUERY_NO_THROTTLE || score < KR_NS_TIMEOUT)) {
update_nsrep(ns, (const knot_dname_t *)k, addr, score);
ns->reputation = reputation;
} else {
/* With 5% chance, probe server with a probability given by its RTT / MAX_RTT */
if ((kr_rand_uint(100) < 5) && (kr_rand_uint(KR_NS_MAX_SCORE) >= score)) {
/* If this is a low-reliability probe, go with TCP to get ICMP reachability check. */
if (score >= KR_NS_LONG) {
qry->flags |= QUERY_TCP;
}
update_nsrep(ns, (const knot_dname_t *)k, addr, score);
ns->reputation = reputation;
return 1; /* Stop evaluation */
}
}
return kr_ok();
}
static int lf_readdir(const char *path, void *buf, fuse_fill_dir_t filler,
off_t offset, struct fuse_file_info *fi) {
if (strcmp(path, "/") != 0)
return -ENOENT;
unsigned int item_count = lru_count();
filler(buf, ".", NULL, 0);
filler(buf, "..", NULL, 0);
for (unsigned int i = 0; i < item_count; i++) {
char *path = lru_get(i);
filler(buf, path+1, NULL, 0);
}
return 0;
}
static unsigned eval_addr_set(pack_t *addr_set, kr_nsrep_lru_t *rttcache, unsigned score, uint8_t **addr)
{
/* Name server is better candidate if it has address record. */
uint8_t *it = pack_head(*addr_set);
while (it != pack_tail(*addr_set)) {
void *val = pack_obj_val(it);
size_t len = pack_obj_len(it);
/* Get RTT for this address (if known) */
unsigned *cached = rttcache ? lru_get(rttcache, val, len) : NULL;
unsigned addr_score = (cached) ? *cached : KR_NS_GLUED;
/* Give v6 a head start */
unsigned favour = (len == sizeof(struct in6_addr)) ? FAVOUR_IPV6 : 0;
if (addr_score < score + favour) {
*addr = it;
score = addr_score;
}
it = pack_obj_next(it);
}
return score;
}
int object_cache_isvalid(u64 oid) {
return objectroot != NULL && lru_get(object_cache_status, &oid) != NULL;
}
