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ndp: separate & clean next hop & l2 determination
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Determining the next hop and the corresponding L2 address are split up
in two steps. No next hop look up is performed for link-local addresses
any more. Destination cache has been disabled.
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@OlegHahm
OlegHahm committed Aug 14, 2015
1 parent a967fab commit 8b15b9c
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Showing 4 changed files with 71 additions and 59 deletions.
27 changes: 23 additions & 4 deletions sys/include/net/ng_ndp/node.h
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Original file line number Diff line number Diff line change
Expand Up @@ -25,14 +25,33 @@ extern "C" {
#endif

/**
* @brief Get link-layer address and interface for next hop to destination
* IPv6 address.
* @brief Next hop determination for a destination address that is not on-link.
*
* @param[out] l2addr The link-layer for the next hop to @p dst.
* @see <a href="https://tools.ietf.org/html/rfc4861#section-3">
* RFC 4861, section 3
* </a>
*
* @param[out] next_hop_ip Will be filled with IPv6 address of the next hop
* or NULL if no next hop could be determined.
* @param[in,out] iface Will be filled with the interface id that has to be
* used for reaching the next hop.
* @param[in] dst The destination IPv6 address.
*
* @return true, if a next hop could be determined.
* @return false otherwise
*/
bool ng_ndp_node_next_hop_ipv6_addr(ipv6_addr_t *next_hop_ip,
kernel_pid_t *iface, ipv6_addr_t *dst);

/**
* @brief Get link-layer address a given IPv6 address.
*
* @param[out] l2addr The link-layer of @p dst.
* @param[out] l2addr_len Length of @p l2addr.
* @param[in] iface The interface to search the next hop on.
* May be @ref KERNEL_PID_UNDEF if not specified.
* @param[in] dst An IPv6 address to search the next hop for.
* @param[in] dst The IPv6 address to search the link-layer
* address hop for.
* @param[in] pkt Packet to send to @p dst. Leave NULL if you
* just want to get the addresses.
*
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15 changes: 14 additions & 1 deletion sys/net/network_layer/ng_ipv6/ng_ipv6.c
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Original file line number Diff line number Diff line change
Expand Up @@ -550,10 +550,23 @@ static void _send(ng_pktsnip_t *pkt, bool prep_hdr)
ng_netapi_receive(ng_ipv6_pid, rcv_pkt);
}
else {
/* forwarding packet */
ipv6_addr_t next_hop_ip;
/* determining next hop's IP address */
if (ipv6_addr_is_link_local(&(hdr->dst))) {
memcpy(&next_hop_ip, &(hdr->dst), sizeof(ipv6_addr_t));
}
else if (!ng_ndp_node_next_hop_ipv6_addr(&next_hop_ip, &iface,
&(hdr->dst))) {
DEBUG("ipv6: error determining next hop's IPv6 address\n");
return;
}

/* determining next hop's layer 2 address */
uint8_t l2addr_len = NG_IPV6_NC_L2_ADDR_MAX;
uint8_t l2addr[l2addr_len];

iface = _next_hop_l2addr(l2addr, &l2addr_len, iface, &hdr->dst, pkt);
iface = _next_hop_l2addr(l2addr, &l2addr_len, iface, &next_hop_ip, pkt);

if (iface == KERNEL_PID_UNDEF) {
DEBUG("ipv6: error determining next hop's link layer address\n");
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2 changes: 1 addition & 1 deletion sys/net/network_layer/ng_ndp/ng_ndp.c
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Original file line number Diff line number Diff line change
Expand Up @@ -32,7 +32,7 @@

#include "net/ng_ndp.h"

#define ENABLE_DEBUG (0)
#define ENABLE_DEBUG (1)
#include "debug.h"

#if ENABLE_DEBUG
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86 changes: 33 additions & 53 deletions sys/net/network_layer/ng_ndp/node/ng_ndp_node.c
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Original file line number Diff line number Diff line change
Expand Up @@ -55,63 +55,43 @@ static ng_pktqueue_t *_alloc_pkt_node(ng_pktsnip_t *pkt)
return NULL;
}

kernel_pid_t ng_ndp_node_next_hop_l2addr(uint8_t *l2addr, uint8_t *l2addr_len,
kernel_pid_t iface, ipv6_addr_t *dst,
ng_pktsnip_t *pkt)
bool ng_ndp_node_next_hop_ipv6_addr(ipv6_addr_t *next_hop_ip,
kernel_pid_t *iface,
ipv6_addr_t *dst)
{
ng_ipv6_nc_t *nc_entry;
ipv6_addr_t *next_hop_ip = NULL, *prefix = NULL;

#ifdef MODULE_NG_IPV6_EXT_RH
next_hop_ip = ng_ipv6_ext_rh_next_hop(hdr);
if (next_hop_ip != NULL) {
return true;
}
#endif
#ifdef MODULE_FIB
/* don't look-up link local addresses in FIB */
if (!ipv6_addr_is_link_local(dst)) {
size_t next_hop_size = sizeof(ipv6_addr_t);
uint32_t next_hop_flags = 0;
ipv6_addr_t next_hop_actual; /* FIB copies address into this variable */

if ((next_hop_ip == NULL) &&
(fib_get_next_hop(&iface, next_hop_actual.u8, &next_hop_size,
&next_hop_flags, (uint8_t *)dst,
sizeof(ipv6_addr_t), 0) >= 0) &&
(next_hop_size == sizeof(ipv6_addr_t))) {
size_t next_hop_size = sizeof(ipv6_addr_t);
uint32_t next_hop_flags = 0;
ipv6_addr_t next_hop_actual;

if ((fib_get_next_hop(iface, next_hop_actual.u8, &next_hop_size,
&next_hop_flags, (uint8_t *)dst,
sizeof(ipv6_addr_t), 0) >= 0) &&
(next_hop_size == sizeof(ipv6_addr_t))) {
next_hop_ip = &next_hop_actual;
}
return true;
}
#endif

if ((next_hop_ip == NULL)) { /* no route to host */
if (iface == KERNEL_PID_UNDEF) {
/* ng_ipv6_netif_t doubles as prefix list */
iface = ng_ipv6_netif_find_by_prefix(&prefix, dst);
}
else {
/* ng_ipv6_netif_t doubles as prefix list */
prefix = ng_ipv6_netif_match_prefix(iface, dst);
}

if ((prefix != NULL) && /* prefix is on-link */
(ng_ipv6_netif_addr_get(prefix)->flags &
NG_IPV6_NETIF_ADDR_FLAGS_NDP_ON_LINK)) {
next_hop_ip = dst;
}
}

/* dst has not an on-link prefix */
if (next_hop_ip == NULL) {
next_hop_ip = ng_ndp_internal_default_router();
next_hop_ip = ng_ndp_internal_default_router();
if (next_hop_ip != NULL) {
return true;
}
return false;
}

kernel_pid_t ng_ndp_node_next_hop_l2addr(uint8_t *l2addr, uint8_t *l2addr_len,
kernel_pid_t iface, ipv6_addr_t *dst,
ng_pktsnip_t *pkt)
{
assert(dst != NULL);

if (next_hop_ip == NULL) {
next_hop_ip = dst; /* Just look if it's in the neighbor cache
* (aka on-link but not registered in prefix list as such) */
}

/* start address resolution */
nc_entry = ng_ipv6_nc_get(iface, next_hop_ip);
ng_ipv6_nc_t *nc_entry = ng_ipv6_nc_get(iface, dst);

if ((nc_entry != NULL) && ng_ipv6_nc_is_reachable(nc_entry)) {
DEBUG("ndp node: found reachable neighbor (%s => ",
Expand All @@ -133,8 +113,8 @@ kernel_pid_t ng_ndp_node_next_hop_l2addr(uint8_t *l2addr, uint8_t *l2addr_len,
ng_pktqueue_t *pkt_node;
ipv6_addr_t dst_sol;

nc_entry = ng_ipv6_nc_add(iface, next_hop_ip, NULL, 0,
NG_IPV6_NC_STATE_INCOMPLETE << NG_IPV6_NC_STATE_POS);
nc_entry = ng_ipv6_nc_add(iface, dst, NULL, 0,
NG_IPV6_NC_STATE_INCOMPLETE << NG_IPV6_NC_STATE_POS);

if (nc_entry == NULL) {
DEBUG("ndp node: could not create neighbor cache entry\n");
Expand All @@ -153,15 +133,15 @@ kernel_pid_t ng_ndp_node_next_hop_l2addr(uint8_t *l2addr, uint8_t *l2addr_len,
}

/* address resolution */
ipv6_addr_set_solicited_nodes(&dst_sol, next_hop_ip);
ipv6_addr_set_solicited_nodes(&dst_sol, dst);

if (iface == KERNEL_PID_UNDEF) {
timex_t t = { 0, NG_NDP_RETRANS_TIMER };
kernel_pid_t ifs[NG_NETIF_NUMOF];
size_t ifnum = ng_netif_get(ifs);

for (size_t i = 0; i < ifnum; i++) {
ng_ndp_internal_send_nbr_sol(ifs[i], next_hop_ip, &dst_sol);
ng_ndp_internal_send_nbr_sol(ifs[i], dst, &dst_sol);
}

vtimer_remove(&nc_entry->nbr_sol_timer);
Expand All @@ -171,7 +151,7 @@ kernel_pid_t ng_ndp_node_next_hop_l2addr(uint8_t *l2addr, uint8_t *l2addr_len,
else {
ng_ipv6_netif_t *ipv6_iface = ng_ipv6_netif_get(iface);

ng_ndp_internal_send_nbr_sol(iface, next_hop_ip, &dst_sol);
ng_ndp_internal_send_nbr_sol(iface, dst, &dst_sol);

mutex_lock(&ipv6_iface->mutex);
vtimer_remove(&nc_entry->nbr_sol_timer);
Expand All @@ -180,9 +160,9 @@ kernel_pid_t ng_ndp_node_next_hop_l2addr(uint8_t *l2addr, uint8_t *l2addr_len,
NG_NDP_MSG_NBR_SOL_RETRANS, nc_entry);
mutex_unlock(&ipv6_iface->mutex);
}
}
}

return KERNEL_PID_UNDEF;
return KERNEL_PID_UNDEF;
}


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