ipv6_addr_t *gnrc_ipv6_netif_match_prefix(kernel_pid_t pid, const ipv6_addr_t *prefix)
{
ipv6_addr_t *res = NULL;
gnrc_ipv6_netif_t *iface = gnrc_ipv6_netif_get(pid);
mutex_lock(&(iface->mutex));
if (_find_by_prefix_unsafe(&res, iface, prefix, NULL) > 0) {
mutex_unlock(&(iface->mutex));
return res;
}
mutex_unlock(&(iface->mutex));
return NULL;
}
static ng_ipv6_addr_t *_match_prefix(kernel_pid_t pid, const ng_ipv6_addr_t *addr,
bool only_unicast)
{
ng_ipv6_addr_t *res = NULL;
ng_ipv6_netif_t *iface = ng_ipv6_netif_get(pid);
mutex_lock(&(iface->mutex));
if (_find_by_prefix_unsafe(&res, iface, addr, only_unicast) > 0) {
mutex_unlock(&(iface->mutex));
return res;
}
mutex_unlock(&(iface->mutex));
return NULL;
}
kernel_pid_t ng_ipv6_netif_find_by_prefix(ng_ipv6_addr_t **out, const ng_ipv6_addr_t *prefix)
{
uint8_t best_match = 0;
ng_ipv6_addr_t *tmp_res = NULL;
kernel_pid_t res = KERNEL_PID_UNDEF;
for (int i = 0; i < NG_NETIF_NUMOF; i++) {
uint8_t match;
mutex_lock(&(ipv6_ifs[i].mutex));
match = _find_by_prefix_unsafe(&tmp_res, ipv6_ifs + i, prefix, false);
if (match > best_match) {
if (out != NULL) {
*out = tmp_res;
}
res = ipv6_ifs[i].pid;
best_match = match;
}
mutex_unlock(&(ipv6_ifs[i].mutex));
}
#if ENABLE_DEBUG
if (res != KERNEL_PID_UNDEF) {
DEBUG("Found %s on interface %" PRIkernel_pid " globally matching ",
ng_ipv6_addr_to_str(addr_str, *out, sizeof(addr_str)),
res);
DEBUG("%s by %" PRIu8 " bits\n",
ng_ipv6_addr_to_str(addr_str, prefix, sizeof(addr_str)),
best_match);
}
else {
DEBUG("Did not found any address globally matching %s\n",
ng_ipv6_addr_to_str(addr_str, prefix, sizeof(addr_str)));
}
#endif
return res;
}
/** @brief Find the best candidate among the configured addresses
* for a certain destination address according to the 8 rules
* specified in RFC 6734, section 5.
* @see <a href="http://tools.ietf.org/html/rfc6724#section-5">
* RFC6724, section 5
* </a>
*
* @param[in] iface The interface for sending.
* @param[in] dst The destination IPv6 address.
* @param[in, out] candidate_set The preselected set of candidate addresses as
* a bitfield.
*
* @pre @p dst is not unspecified.
*
* @return The best matching candidate found on @p iface, may be NULL if none
* is found.
*/
static ipv6_addr_t *_source_address_selection(gnrc_ipv6_netif_t *iface, const ipv6_addr_t *dst,
uint8_t *candidate_set)
{
/* create temporary set for assigning "points" to candidates wining in the
* corresponding rules.
*/
uint8_t winner_set[GNRC_IPV6_NETIF_ADDR_NUMOF];
memset(winner_set, 0, GNRC_IPV6_NETIF_ADDR_NUMOF);
uint8_t max_pts = 0;
/* _create_candidate_set() assures that `dest` is not unspecified and if
* `dst` is loopback rule 1 will fire anyway. */
uint8_t dst_scope = _get_scope(dst, true);
DEBUG("finding the best match within the source address candidates\n");
for (int i = 0; i < GNRC_IPV6_NETIF_ADDR_NUMOF; i++) {
gnrc_ipv6_netif_addr_t *iter = &(iface->addrs[i]);
DEBUG("Checking address: %s\n",
ipv6_addr_to_str(addr_str, &(iter->addr), sizeof(addr_str)));
/* entries which are not part of the candidate set can be ignored */
if (!(bf_isset(candidate_set, i))) {
DEBUG("Not part of the candidate set - skipping\n");
continue;
}
/* Rule 1: if we have an address configured that equals the destination
* use this one as source */
if (ipv6_addr_equal(&(iter->addr), dst)) {
DEBUG("Ease one - rule 1\n");
return &(iter->addr);
}
/* Rule 2: Prefer appropriate scope. */
/* both link local */
uint8_t candidate_scope = _get_scope(&(iter->addr), false);
if (candidate_scope == dst_scope) {
DEBUG("winner for rule 2 (same scope) found\n");
winner_set[i] += RULE_2A_PTS;
if (winner_set[i] > max_pts) {
max_pts = RULE_2A_PTS;
}
}
else if (candidate_scope < dst_scope) {
DEBUG("winner for rule 2 (smaller scope) found\n");
winner_set[i] += RULE_2B_PTS;
if (winner_set[i] > max_pts) {
max_pts = winner_set[i];
}
}
/* Rule 3: Avoid deprecated addresses. */
if (iter->preferred > 0) {
DEBUG("winner for rule 3 found\n");
winner_set[i] += RULE_3_PTS;
if (winner_set[i] > max_pts) {
max_pts = winner_set[i];
}
}
/* Rule 4: Prefer home addresses.
* Does not apply, gnrc does not support Mobile IP.
* TODO: update as soon as gnrc supports Mobile IP
*/
/* Rule 5: Prefer outgoing interface.
* RFC 6724 says:
* "It is RECOMMENDED that the candidate source addresses be the set of
* unicast addresses assigned to the interface that will be used to
* send to the destination (the "outgoing" interface). On routers,
* the candidate set MAY include unicast addresses assigned to any
* interface that forwards packets, subject to the restrictions
* described below."
* Currently this implementation uses ALWAYS source addresses assigned
* to the outgoing interface. Hence, Rule 5 is always fulfilled.
*/
/* Rule 6: Prefer matching label.
* Flow labels are currently not supported by gnrc.
* TODO: update as soon as gnrc supports flow labels
*/
/* Rule 7: Prefer temporary addresses.
* Temporary addresses are currently not supported by gnrc.
* TODO: update as soon as gnrc supports temporary addresses
*/
}
/* reset candidate set to mark winners */
memset(candidate_set, 0, (GNRC_IPV6_NETIF_ADDR_NUMOF / 8) + 1);
/* check if we have a clear winner */
/* collect candidates with maximum points */
for (int i = 0; i < GNRC_IPV6_NETIF_ADDR_NUMOF; i++) {
if (winner_set[i] == max_pts) {
bf_set(candidate_set, i);
}
}
/* otherwise apply rule 8: Use longest matching prefix. */
ipv6_addr_t *res = NULL;
_find_by_prefix_unsafe(&res, iface, dst, candidate_set);
return res;
}
