bool rrl_slip_roll(int n_slip)
{
/* Now n_slip means every Nth answer slips.
* That represents a chance of 1/N that answer slips.
* Therefore, on average, from 100 answers 100/N will slip. */
int threshold = RRL_SLIP_MAX / n_slip;
int roll = dnssec_random_uint16_t() % RRL_SLIP_MAX;
return (roll < threshold);
}
knot_pkt_t* create_empty_packet(const size_t max_size)
{
// Create packet skeleton.
knot_pkt_t *packet = knot_pkt_new(NULL, max_size, NULL);
if (packet == NULL) {
DBG_NULL;
return NULL;
}
// Set random sequence id.
knot_wire_set_id(packet->wire, dnssec_random_uint16_t());
return packet;
}
/*! \brief Create zone query packet. */
static knot_pkt_t *zone_query(const zone_t *zone, uint16_t pkt_type, knot_mm_t *mm)
{
/* Determine query type and opcode. */
uint16_t query_type = KNOT_RRTYPE_SOA;
uint16_t opcode = KNOT_OPCODE_QUERY;
switch(pkt_type) {
case KNOT_QUERY_AXFR: query_type = KNOT_RRTYPE_AXFR; break;
case KNOT_QUERY_IXFR: query_type = KNOT_RRTYPE_IXFR; break;
case KNOT_QUERY_NOTIFY: opcode = KNOT_OPCODE_NOTIFY; break;
}
knot_pkt_t *pkt = knot_pkt_new(NULL, KNOT_WIRE_MAX_PKTSIZE, mm);
if (pkt == NULL) {
return NULL;
}
knot_wire_set_id(pkt->wire, dnssec_random_uint16_t());
knot_wire_set_opcode(pkt->wire, opcode);
if (pkt_type == KNOT_QUERY_NOTIFY) {
knot_wire_set_aa(pkt->wire);
}
knot_pkt_put_question(pkt, zone->name, KNOT_CLASS_IN, query_type);
/* Put current SOA (optional). */
zone_contents_t *contents = zone->contents;
if (pkt_type == KNOT_QUERY_IXFR) { /* RFC1995, SOA in AUTHORITY. */
knot_pkt_begin(pkt, KNOT_AUTHORITY);
knot_rrset_t soa_rr = node_rrset(contents->apex, KNOT_RRTYPE_SOA);
knot_pkt_put(pkt, KNOT_COMPR_HINT_QNAME, &soa_rr, 0);
} else if (pkt_type == KNOT_QUERY_NOTIFY) { /* RFC1996, SOA in ANSWER. */
knot_pkt_begin(pkt, KNOT_ANSWER);
knot_rrset_t soa_rr = node_rrset(contents->apex, KNOT_RRTYPE_SOA);
knot_pkt_put(pkt, KNOT_COMPR_HINT_QNAME, &soa_rr, 0);
}
return pkt;
}
/*! \brief Calculate TCP throttle time (random). */
static inline int tcp_throttle() {
return TCP_THROTTLE_LO + (dnssec_random_uint16_t() % TCP_THROTTLE_HI);
}
