2 * Copyright (c) 2021 Cisco and/or its affiliates.
3 * Licensed under the Apache License, Version 2.0 (the "License");
4 * you may not use this file except in compliance with the License.
5 * You may obtain a copy of the License at:
7 * http://www.apache.org/licenses/LICENSE-2.0
9 * Unless required by applicable law or agreed to in writing, software
10 * distributed under the License is distributed on an "AS IS" BASIS,
11 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 * See the License for the specific language governing permissions and
13 * limitations under the License.
17 #include <vppinfra/types.h>
18 #include <vnet/ip/ip_interface.h>
19 #include <vnet/fib/fib_table.h>
20 #include <vnet/ip/ip6_link.h>
21 #include <vppinfra/byte_order.h>
24 * This file implement source address selection for VPP applications
25 * (e.g. ping, DNS, ICMP)
26 * It does not yet implement full fledged RFC6724 SAS.
27 * SAS assumes every IP enabled interface has an address. The algorithm will
28 * not go and hunt for a suitable IP address on other interfaces than the
29 * output interface or the specified preferred sw_if_index.
30 * That means that an interface with just an IPv6 link-local address must also
31 * be configured with an unnumbered configuration pointing to a numbered
36 ip6_sas_commonlen (const ip6_address_t *a1, const ip6_address_t *a2)
38 u64 fa = clib_net_to_host_u64 (a1->as_u64[0]) ^
39 clib_net_to_host_u64 (a2->as_u64[0]);
42 u64 la = clib_net_to_host_u64 (a1->as_u64[1]) ^
43 clib_net_to_host_u64 (a2->as_u64[1]);
46 return 64 + __builtin_clzll (la);
50 return __builtin_clzll (fa);
55 ip4_sas_commonlen (const ip4_address_t *a1, const ip4_address_t *a2)
58 clib_net_to_host_u32 (a1->as_u32) ^ clib_net_to_host_u32 (a2->as_u32);
61 return __builtin_clz (a);
65 * walk all addresses on an interface:
66 * - prefer a source matching the scope of the destination address.
67 * - last resort pick the source address with the longest
68 * common prefix with destination
69 * NOTE: This should at some point implement RFC6724.
72 ip6_sas_by_sw_if_index (u32 sw_if_index, const ip6_address_t *dst,
75 ip_interface_address_t *ia = 0;
76 ip_lookup_main_t *lm6 = &ip6_main.lookup_main;
77 ip6_address_t *tmp, *bestsrc = 0;
80 if (ip6_address_is_link_local_unicast (dst) ||
81 dst->as_u32[0] == clib_host_to_net_u32 (0xff020000))
83 const ip6_address_t *ll = ip6_get_link_local_address (sw_if_index);
88 ip6_address_copy (src, ll);
92 foreach_ip_interface_address (
93 lm6, ia, sw_if_index, 1, ({
94 if (ia->flags & IP_INTERFACE_ADDRESS_FLAG_STALE)
96 tmp = ip_interface_address_get_address (lm6, ia);
97 l = ip6_sas_commonlen (tmp, dst);
98 if (l > bestlen || bestsrc == 0)
106 ip6_address_copy (src, bestsrc);
113 * walk all addresses on an interface and pick the source address with the
114 * longest common prefix with destination.
117 ip4_sas_by_sw_if_index (u32 sw_if_index, const ip4_address_t *dst,
120 ip_interface_address_t *ia = 0;
121 ip_lookup_main_t *lm4 = &ip4_main.lookup_main;
122 ip4_address_t *tmp, *bestsrc = 0;
125 foreach_ip_interface_address (
126 lm4, ia, sw_if_index, 1, ({
127 if (ia->flags & IP_INTERFACE_ADDRESS_FLAG_STALE)
129 tmp = ip_interface_address_get_address (lm4, ia);
130 l = ip4_sas_commonlen (tmp, dst);
131 if (l > bestlen || bestsrc == 0)
139 src->as_u32 = bestsrc->as_u32;
146 * table_id must be set. Default = 0.
147 * sw_if_index is the interface to pick SA from otherwise ~0 will pick from
148 * outbound interface.
150 * NOTE: What to do if multiple output interfaces?
154 ip6_sas (u32 table_id, u32 sw_if_index, const ip6_address_t *dst,
158 u32 if_index = sw_if_index;
160 /* If sw_if_index is not specified use the output interface. */
161 if (sw_if_index == ~0)
163 clib_memcpy (&prefix.fp_addr.ip6, dst, sizeof (*dst));
164 prefix.fp_proto = FIB_PROTOCOL_IP6;
167 u32 fib_index = fib_table_find (prefix.fp_proto, table_id);
168 if (fib_index == (u32) ~0)
171 fib_node_index_t fei = fib_table_lookup (fib_index, &prefix);
172 if (fei == FIB_NODE_INDEX_INVALID)
175 u32 output_sw_if_index = fib_entry_get_resolving_interface (fei);
176 if (output_sw_if_index == ~0)
178 if_index = output_sw_if_index;
180 return ip6_sas_by_sw_if_index (if_index, dst, src);
184 * table_id must be set. Default = 0.
185 * sw_if_index is the interface to pick SA from otherwise ~0 will pick from
186 * outbound interface.
188 * NOTE: What to do if multiple output interfaces?
192 ip4_sas (u32 table_id, u32 sw_if_index, const ip4_address_t *dst,
196 u32 if_index = sw_if_index;
198 /* If sw_if_index is not specified use the output interface. */
199 if (sw_if_index == ~0)
201 clib_memcpy (&prefix.fp_addr.ip4, dst, sizeof (*dst));
202 prefix.fp_proto = FIB_PROTOCOL_IP4;
205 u32 fib_index = fib_table_find (prefix.fp_proto, table_id);
206 if (fib_index == (u32) ~0)
209 fib_node_index_t fei = fib_table_lookup (fib_index, &prefix);
210 if (fei == FIB_NODE_INDEX_INVALID)
213 u32 output_sw_if_index = fib_entry_get_resolving_interface (fei);
214 if (output_sw_if_index == ~0)
216 if_index = output_sw_if_index;
218 return ip4_sas_by_sw_if_index (if_index, dst, src);