lwip/contrib/addons/ipv6_static_routing/ip6_route_table.c

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/**
* @file
* IPv6 static route table.
*/
/*
* Copyright (c) 2015 Nest Labs, Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without modification,
* are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
* SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
* OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
* OF SUCH DAMAGE.
*
* Author: Pradip De <pradipd@google.com>
*
*
* Please coordinate changes and requests with Pradip De
* <pradipd@google.com>
*/
#include "lwip/opt.h"
#if LWIP_IPV6 /* don't build if not configured for use in lwipopts.h */
#include "ip6_route_table.h"
#include "lwip/def.h"
#include "lwip/mem.h"
#include "lwip/netif.h"
#include "lwip/ip6.h"
#include "lwip/ip6_addr.h"
#include "lwip/nd6.h"
#include "lwip/debug.h"
#include "lwip/stats.h"
#include "string.h"
static struct ip6_route_entry static_route_table[LWIP_IPV6_NUM_ROUTE_ENTRIES];
/**
* Add the ip6 prefix route and target netif into the static route table while
* keeping all entries sorted in decreasing order of prefix length.
* 1. Search from the last entry up to find the correct slot to insert while
* moving entries one position down to create room.
* 2. Insert into empty slot created.
*
* Subsequently, a linear search down the list can be performed to retrieve a
* matching route entry for a Longest Prefix Match.
*
* @param ip6_prefix the route prefix entry to add.
* @param netif pointer to target netif.
* @param gateway the gateway address to use to send through. Has to be link local.
* @param idx return value argument of index where route entry was added in table.
* @return ERR_OK if addition was successful.
* ERR_MEM if table is already full.
* ERR_ARG if passed argument is bad or route already exists in table.
*/
err_t
ip6_add_route_entry(const struct ip6_prefix *ip6_prefix, struct netif *netif, const ip6_addr_t *gateway, s8_t *idx)
{
s8_t i = -1;
err_t retval = ERR_OK;
if (!ip6_prefix_valid(ip6_prefix->prefix_len) || (netif == NULL)) {
retval = ERR_ARG;
goto exit;
}
/* Check if an entry already exists with matching prefix; If so, replace it. */
for (i = 0; i < LWIP_IPV6_NUM_ROUTE_ENTRIES; i++) {
if ((ip6_prefix->prefix_len == static_route_table[i].prefix.prefix_len) &&
memcmp(&ip6_prefix->addr, &static_route_table[i].prefix.addr,
ip6_prefix->prefix_len / 8) == 0) {
/* Prefix matches; replace the netif with the one being added. */
goto insert;
}
}
/* Check if the table is full */
if (static_route_table[LWIP_IPV6_NUM_ROUTE_ENTRIES - 1].netif != NULL) {
retval = ERR_MEM;
goto exit;
}
/* Shift all entries down the table until slot is found */
for (i = LWIP_IPV6_NUM_ROUTE_ENTRIES - 1;
i > 0 && (ip6_prefix->prefix_len > static_route_table[i - 1].prefix.prefix_len); i--) {
SMEMCPY(&static_route_table[i], &static_route_table[i - 1], sizeof(struct ip6_route_entry));
}
insert:
/* Insert into the slot selected */
SMEMCPY(&static_route_table[i].prefix, ip6_prefix, sizeof(struct ip6_prefix));
static_route_table[i].netif = netif;
/* Add gateway to route table */
static_route_table[i].gateway = gateway;
if (idx != NULL) {
*idx = i;
}
exit:
return retval;
}
/**
* Removes the route entry from the static route table.
*
* @param ip6_prefix the route prefix entry to delete.
*/
void
ip6_remove_route_entry(const struct ip6_prefix *ip6_prefix)
{
int i, pos = -1;
for (i = 0; i < LWIP_IPV6_NUM_ROUTE_ENTRIES; i++) {
/* compare prefix to find position to delete */
if (ip6_prefix->prefix_len == static_route_table[i].prefix.prefix_len &&
memcmp(&ip6_prefix->addr, &static_route_table[i].prefix.addr,
ip6_prefix->prefix_len / 8) == 0) {
pos = i;
break;
}
}
if (pos >= 0) {
/* Shift everything beyond pos one slot up */
for (i = pos; i < LWIP_IPV6_NUM_ROUTE_ENTRIES - 1; i++) {
SMEMCPY(&static_route_table[i], &static_route_table[i+1], sizeof(struct ip6_route_entry));
if (static_route_table[i].netif == NULL) {
break;
}
}
/* Zero the remaining entries */
for (; i < LWIP_IPV6_NUM_ROUTE_ENTRIES; i++) {
ip6_addr_set_zero((&static_route_table[i].prefix.addr));
static_route_table[i].netif = NULL;
}
}
}
/**
* Finds the appropriate route entry in the static route table corresponding to the given
* destination IPv6 address. Since the entries in the route table are kept sorted in decreasing
* order of prefix length, a linear search down the list is performed to retrieve a matching
* index.
*
* @param ip6_dest_addr the destination address to match
* @return the idx of the found route entry; -1 if not found.
*/
s8_t
ip6_find_route_entry(const ip6_addr_t *ip6_dest_addr)
{
s8_t i, idx = -1;
/* Search prefix in the sorted(decreasing order of prefix length) list */
for(i = 0; i < LWIP_IPV6_NUM_ROUTE_ENTRIES; i++) {
if (memcmp(ip6_dest_addr, &static_route_table[i].prefix.addr,
static_route_table[i].prefix.prefix_len / 8) == 0) {
idx = i;
break;
}
}
return idx;
}
/**
* Finds the appropriate network interface for a given IPv6 address from a routing table with
* static IPv6 routes.
*
* @param src the source IPv6 address, if known
* @param dest the destination IPv6 address for which to find the route
* @return the netif on which to send to reach dest
*/
struct netif *
ip6_static_route(const ip6_addr_t *src, const ip6_addr_t *dest)
{
int i;
LWIP_UNUSED_ARG(src);
/* Perform table lookup */
i = ip6_find_route_entry(dest);
if (i >= 0) {
return static_route_table[i].netif;
} else {
return NULL;
}
}
/**
* Finds the gateway IP6 address for a given destination IPv6 address and target netif
* from a routing table with static IPv6 routes.
*
* @param netif the netif used for sending
* @param dest the destination IPv6 address
* @return the ip6 address of the gateway to forward packet to
*/
const ip6_addr_t *
ip6_get_gateway(struct netif *netif, const ip6_addr_t *dest)
{
const ip6_addr_t *ret_gw = NULL;
const int i = ip6_find_route_entry(dest);
LWIP_UNUSED_ARG(netif);
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if (i >= 0) {
if (static_route_table[i].gateway != NULL) {
ret_gw = static_route_table[i].gateway;
}
}
return ret_gw;
}
/**
* Returns the top of the route table.
* This should be used for debug printing only.
*
* @return the top of the route table.
*/
const struct ip6_route_entry *
ip6_get_route_table(void)
{
return static_route_table;
}
#endif /* LWIP_IPV6 */