[457] | 1 | /**
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| 2 | * @file
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| 3 | * IPv6 static route table.
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| 4 | */
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| 5 |
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| 6 | /*
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| 7 | * Copyright (c) 2015 Nest Labs, Inc.
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| 8 | * All rights reserved.
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| 9 | *
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| 10 | * Redistribution and use in source and binary forms, with or without modification,
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| 11 | * are permitted provided that the following conditions are met:
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| 12 | *
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| 13 | * 1. Redistributions of source code must retain the above copyright notice,
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| 14 | * this list of conditions and the following disclaimer.
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| 15 | * 2. Redistributions in binary form must reproduce the above copyright notice,
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| 16 | * this list of conditions and the following disclaimer in the documentation
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| 17 | * and/or other materials provided with the distribution.
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| 18 | * 3. The name of the author may not be used to endorse or promote products
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| 19 | * derived from this software without specific prior written permission.
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| 20 | *
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| 21 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
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| 22 | * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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| 23 | * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
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| 24 | * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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| 25 | * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
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| 26 | * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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| 27 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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| 28 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
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| 29 | * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
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| 30 | * OF SUCH DAMAGE.
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| 31 | *
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| 32 | * Author: Pradip De <pradipd@google.com>
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| 33 | *
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| 34 | *
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| 35 | * Please coordinate changes and requests with Pradip De
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| 36 | * <pradipd@google.com>
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| 37 | */
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| 38 |
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| 39 | #include "lwip/opt.h"
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| 40 |
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| 41 | #if LWIP_IPV6 /* don't build if not configured for use in lwipopts.h */
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| 42 |
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| 43 | #include "ip6_route_table.h"
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| 44 | #include "lwip/def.h"
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| 45 | #include "lwip/mem.h"
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| 46 | #include "lwip/netif.h"
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| 47 | #include "lwip/ip6.h"
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| 48 | #include "lwip/ip6_addr.h"
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| 49 | #include "lwip/nd6.h"
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| 50 | #include "lwip/debug.h"
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| 51 | #include "lwip/stats.h"
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| 52 |
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| 53 | #include "string.h"
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| 54 |
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| 55 | static struct ip6_route_entry static_route_table[LWIP_IPV6_NUM_ROUTE_ENTRIES];
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| 56 |
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| 57 | /**
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| 58 | * Add the ip6 prefix route and target netif into the static route table while
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| 59 | * keeping all entries sorted in decreasing order of prefix length.
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| 60 | * 1. Search from the last entry up to find the correct slot to insert while
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| 61 | * moving entries one position down to create room.
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| 62 | * 2. Insert into empty slot created.
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| 63 | *
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| 64 | * Subsequently, a linear search down the list can be performed to retrieve a
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| 65 | * matching route entry for a Longest Prefix Match.
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| 66 | *
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| 67 | * @param ip6_prefix the route prefix entry to add.
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| 68 | * @param netif pointer to target netif.
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| 69 | * @param gateway the gateway address to use to send through. Has to be link local.
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| 70 | * @param idx return value argument of index where route entry was added in table.
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| 71 | * @return ERR_OK if addition was successful.
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| 72 | * ERR_MEM if table is already full.
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| 73 | * ERR_ARG if passed argument is bad or route already exists in table.
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| 74 | */
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| 75 | err_t
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| 76 | ip6_add_route_entry(const struct ip6_prefix *ip6_prefix, struct netif *netif, const ip6_addr_t *gateway, s8_t *idx)
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| 77 | {
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| 78 | s8_t i = -1;
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| 79 | err_t retval = ERR_OK;
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| 80 |
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| 81 | if (!ip6_prefix_valid(ip6_prefix->prefix_len) || (netif == NULL)) {
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| 82 | retval = ERR_ARG;
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| 83 | goto exit;
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| 84 | }
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| 85 |
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| 86 | /* Check if an entry already exists with matching prefix; If so, replace it. */
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| 87 | for (i = 0; i < LWIP_IPV6_NUM_ROUTE_ENTRIES; i++) {
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| 88 | if ((ip6_prefix->prefix_len == static_route_table[i].prefix.prefix_len) &&
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| 89 | memcmp(&ip6_prefix->addr, &static_route_table[i].prefix.addr,
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| 90 | ip6_prefix->prefix_len / 8) == 0) {
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| 91 | /* Prefix matches; replace the netif with the one being added. */
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| 92 | goto insert;
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| 93 | }
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| 94 | }
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| 95 |
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| 96 | /* Check if the table is full */
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| 97 | if (static_route_table[LWIP_IPV6_NUM_ROUTE_ENTRIES - 1].netif != NULL) {
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| 98 | retval = ERR_MEM;
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| 99 | goto exit;
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| 100 | }
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| 101 |
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| 102 | /* Shift all entries down the table until slot is found */
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| 103 | for (i = LWIP_IPV6_NUM_ROUTE_ENTRIES - 1;
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| 104 | i > 0 && (ip6_prefix->prefix_len > static_route_table[i - 1].prefix.prefix_len); i--) {
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| 105 | SMEMCPY(&static_route_table[i], &static_route_table[i - 1], sizeof(struct ip6_route_entry));
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| 106 | }
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| 107 |
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| 108 | insert:
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| 109 | /* Insert into the slot selected */
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| 110 | SMEMCPY(&static_route_table[i].prefix, ip6_prefix, sizeof(struct ip6_prefix));
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| 111 | static_route_table[i].netif = netif;
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| 112 |
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| 113 | /* Add gateway to route table */
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| 114 | static_route_table[i].gateway = gateway;
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| 115 |
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| 116 | if (idx != NULL) {
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| 117 | *idx = i;
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| 118 | }
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| 119 |
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| 120 | exit:
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| 121 | return retval;
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| 122 | }
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| 123 |
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| 124 | /**
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| 125 | * Removes the route entry from the static route table.
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| 126 | *
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| 127 | * @param ip6_prefix the route prefix entry to delete.
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| 128 | */
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| 129 | void
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| 130 | ip6_remove_route_entry(const struct ip6_prefix *ip6_prefix)
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| 131 | {
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| 132 | int i, pos = -1;
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| 133 |
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| 134 | for (i = 0; i < LWIP_IPV6_NUM_ROUTE_ENTRIES; i++) {
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| 135 | /* compare prefix to find position to delete */
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| 136 | if (ip6_prefix->prefix_len == static_route_table[i].prefix.prefix_len &&
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| 137 | memcmp(&ip6_prefix->addr, &static_route_table[i].prefix.addr,
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| 138 | ip6_prefix->prefix_len / 8) == 0) {
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| 139 | pos = i;
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| 140 | break;
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| 141 | }
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| 142 | }
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| 143 |
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| 144 | if (pos >= 0) {
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| 145 | /* Shift everything beyond pos one slot up */
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| 146 | for (i = pos; i < LWIP_IPV6_NUM_ROUTE_ENTRIES - 1; i++) {
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| 147 | SMEMCPY(&static_route_table[i], &static_route_table[i+1], sizeof(struct ip6_route_entry));
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| 148 | if (static_route_table[i].netif == NULL) {
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| 149 | break;
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| 150 | }
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| 151 | }
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| 152 | /* Zero the remaining entries */
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| 153 | for (; i < LWIP_IPV6_NUM_ROUTE_ENTRIES; i++) {
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| 154 | ip6_addr_set_zero((&static_route_table[i].prefix.addr));
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| 155 | static_route_table[i].netif = NULL;
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| 156 | }
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| 157 | }
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| 158 | }
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| 159 |
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| 160 | /**
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| 161 | * Finds the appropriate route entry in the static route table corresponding to the given
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| 162 | * destination IPv6 address. Since the entries in the route table are kept sorted in decreasing
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| 163 | * order of prefix length, a linear search down the list is performed to retrieve a matching
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| 164 | * index.
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| 165 | *
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| 166 | * @param ip6_dest_addr the destination address to match
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| 167 | * @return the idx of the found route entry; -1 if not found.
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| 168 | */
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| 169 | s8_t
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| 170 | ip6_find_route_entry(const ip6_addr_t *ip6_dest_addr)
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| 171 | {
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| 172 | s8_t i, idx = -1;
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| 173 |
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| 174 | /* Search prefix in the sorted(decreasing order of prefix length) list */
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| 175 | for(i = 0; i < LWIP_IPV6_NUM_ROUTE_ENTRIES; i++) {
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| 176 | if (memcmp(ip6_dest_addr, &static_route_table[i].prefix.addr,
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| 177 | static_route_table[i].prefix.prefix_len / 8) == 0) {
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| 178 | idx = i;
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| 179 | break;
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| 180 | }
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| 181 | }
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| 182 |
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| 183 | return idx;
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| 184 | }
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| 185 |
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| 186 | /**
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| 187 | * Finds the appropriate network interface for a given IPv6 address from a routing table with
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| 188 | * static IPv6 routes.
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| 189 | *
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| 190 | * @param src the source IPv6 address, if known
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| 191 | * @param dest the destination IPv6 address for which to find the route
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| 192 | * @return the netif on which to send to reach dest
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| 193 | */
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| 194 | struct netif *
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| 195 | ip6_static_route(const ip6_addr_t *src, const ip6_addr_t *dest)
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| 196 | {
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| 197 | int i;
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| 198 |
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| 199 | LWIP_UNUSED_ARG(src);
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| 200 |
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| 201 | /* Perform table lookup */
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| 202 | i = ip6_find_route_entry(dest);
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| 203 |
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| 204 | if (i >= 0) {
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| 205 | return static_route_table[i].netif;
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| 206 | } else {
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| 207 | return NULL;
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| 208 | }
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| 209 | }
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| 210 |
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| 211 | /**
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| 212 | * Finds the gateway IP6 address for a given destination IPv6 address and target netif
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| 213 | * from a routing table with static IPv6 routes.
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| 214 | *
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| 215 | * @param netif the netif used for sending
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| 216 | * @param dest the destination IPv6 address
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| 217 | * @return the ip6 address of the gateway to forward packet to
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| 218 | */
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| 219 | const ip6_addr_t *
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| 220 | ip6_get_gateway(struct netif *netif, const ip6_addr_t *dest)
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| 221 | {
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| 222 | const ip6_addr_t *ret_gw = NULL;
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| 223 | const int i = ip6_find_route_entry(dest);
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| 224 |
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| 225 | LWIP_UNUSED_ARG(netif);
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| 226 |
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| 227 | if (i >= 0) {
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| 228 | if (static_route_table[i].gateway != NULL) {
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| 229 | ret_gw = static_route_table[i].gateway;
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| 230 | }
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| 231 | }
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| 232 |
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| 233 | return ret_gw;
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| 234 | }
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| 235 |
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| 236 | /**
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| 237 | * Returns the top of the route table.
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| 238 | * This should be used for debug printing only.
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| 239 | *
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| 240 | * @return the top of the route table.
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| 241 | */
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| 242 | const struct ip6_route_entry *
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| 243 | ip6_get_route_table(void)
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| 244 | {
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| 245 | return static_route_table;
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| 246 | }
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| 247 |
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| 248 | #endif /* LWIP_IPV6 */
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