1 | /**
|
---|
2 | * @file
|
---|
3 | *
|
---|
4 | * IPv6 address scopes, zones, and scoping policy.
|
---|
5 | *
|
---|
6 | * This header provides the means to implement support for IPv6 address scopes,
|
---|
7 | * as per RFC 4007. An address scope can be either global or more constrained.
|
---|
8 | * In lwIP, we say that an address "has a scope" or "is scoped" when its scope
|
---|
9 | * is constrained, in which case the address is meaningful only in a specific
|
---|
10 | * "zone." For unicast addresses, only link-local addresses have a scope; in
|
---|
11 | * that case, the scope is the link. For multicast addresses, there are various
|
---|
12 | * scopes defined by RFC 4007 and others. For any constrained scope, a system
|
---|
13 | * must establish a (potentially one-to-many) mapping between zones and local
|
---|
14 | * interfaces. For example, a link-local address is valid on only one link (its
|
---|
15 | * zone). That link may be attached to one or more local interfaces. The
|
---|
16 | * decisions on which scopes are constrained and the mapping between zones and
|
---|
17 | * interfaces is together what we refer to as the "scoping policy" - more on
|
---|
18 | * this in a bit.
|
---|
19 | *
|
---|
20 | * In lwIP, each IPv6 address has an associated zone index. This zone index may
|
---|
21 | * be set to "no zone" (IP6_NO_ZONE, 0) or an actual zone. We say that an
|
---|
22 | * address "has a zone" or "is zoned" when its zone index is *not* set to "no
|
---|
23 | * zone." In lwIP, in principle, each address should be "properly zoned," which
|
---|
24 | * means that if the address has a zone if and only if has a scope. As such, it
|
---|
25 | * is a rule that an unscoped (e.g., global) address must never have a zone.
|
---|
26 | * Even though one could argue that there is always one zone even for global
|
---|
27 | * scopes, this rule exists for implementation simplicity. Violation of the
|
---|
28 | * rule will trigger assertions or otherwise result in undesired behavior.
|
---|
29 | *
|
---|
30 | * Backward compatibility prevents us from requiring that applications always
|
---|
31 | * provide properly zoned addresses. We do enforce the rule that the in the
|
---|
32 | * lwIP link layer (everything below netif->output_ip6() and in particular ND6)
|
---|
33 | * *all* addresses are properly zoned. Thus, on the output paths down the
|
---|
34 | * stack, various places deal with the case of addresses that lack a zone.
|
---|
35 | * Some of them are best-effort for efficiency (e.g. the PCB bind and connect
|
---|
36 | * API calls' attempts to add missing zones); ultimately the IPv6 output
|
---|
37 | * handler (@ref ip6_output_if_src) will set a zone if necessary.
|
---|
38 | *
|
---|
39 | * Aside from dealing with scoped addresses lacking a zone, a proper IPv6
|
---|
40 | * implementation must also ensure that a packet with a scoped source and/or
|
---|
41 | * destination address does not leave its zone. This is currently implemented
|
---|
42 | * in the input and forward functions. However, for output, these checks are
|
---|
43 | * deliberately omitted in order to keep the implementation lightweight. The
|
---|
44 | * routing algorithm in @ref ip6_route will take decisions such that it will
|
---|
45 | * not cause zone violations unless the application sets bad addresses, though.
|
---|
46 | *
|
---|
47 | * In terms of scoping policy, lwIP implements the default policy from RFC 4007
|
---|
48 | * using macros in this file. This policy considers link-local unicast
|
---|
49 | * addresses and (only) interface-local and link-local multicast addresses as
|
---|
50 | * having a scope. For all these addresses, the zone is equal to the interface.
|
---|
51 | * As shown below in this file, it is possible to implement a custom policy.
|
---|
52 | */
|
---|
53 |
|
---|
54 | /*
|
---|
55 | * Copyright (c) 2017 The MINIX 3 Project.
|
---|
56 | * All rights reserved.
|
---|
57 | *
|
---|
58 | * Redistribution and use in source and binary forms, with or without modification,
|
---|
59 | * are permitted provided that the following conditions are met:
|
---|
60 | *
|
---|
61 | * 1. Redistributions of source code must retain the above copyright notice,
|
---|
62 | * this list of conditions and the following disclaimer.
|
---|
63 | * 2. Redistributions in binary form must reproduce the above copyright notice,
|
---|
64 | * this list of conditions and the following disclaimer in the documentation
|
---|
65 | * and/or other materials provided with the distribution.
|
---|
66 | * 3. The name of the author may not be used to endorse or promote products
|
---|
67 | * derived from this software without specific prior written permission.
|
---|
68 | *
|
---|
69 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
|
---|
70 | * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
|
---|
71 | * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
|
---|
72 | * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
|
---|
73 | * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
|
---|
74 | * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
|
---|
75 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
|
---|
76 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
|
---|
77 | * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
|
---|
78 | * OF SUCH DAMAGE.
|
---|
79 | *
|
---|
80 | * This file is part of the lwIP TCP/IP stack.
|
---|
81 | *
|
---|
82 | * Author: David van Moolenbroek <david@minix3.org>
|
---|
83 | *
|
---|
84 | */
|
---|
85 | #ifndef LWIP_HDR_IP6_ZONE_H
|
---|
86 | #define LWIP_HDR_IP6_ZONE_H
|
---|
87 |
|
---|
88 | #ifdef __cplusplus
|
---|
89 | extern "C" {
|
---|
90 | #endif
|
---|
91 |
|
---|
92 | /**
|
---|
93 | * @defgroup ip6_zones IPv6 Zones
|
---|
94 | * @ingroup ip6
|
---|
95 | * @{
|
---|
96 | */
|
---|
97 |
|
---|
98 | #if LWIP_IPV6 /* don't build if not configured for use in lwipopts.h */
|
---|
99 |
|
---|
100 | /** Identifier for "no zone". */
|
---|
101 | #define IP6_NO_ZONE 0
|
---|
102 |
|
---|
103 | #if LWIP_IPV6_SCOPES
|
---|
104 |
|
---|
105 | /** Zone initializer for static IPv6 address initialization, including comma. */
|
---|
106 | #define IPADDR6_ZONE_INIT , IP6_NO_ZONE
|
---|
107 |
|
---|
108 | /** Return the zone index of the given IPv6 address; possibly "no zone". */
|
---|
109 | #define ip6_addr_zone(ip6addr) ((ip6addr)->zone)
|
---|
110 |
|
---|
111 | /** Does the given IPv6 address have a zone set? (0/1) */
|
---|
112 | #define ip6_addr_has_zone(ip6addr) (ip6_addr_zone(ip6addr) != IP6_NO_ZONE)
|
---|
113 |
|
---|
114 | /** Set the zone field of an IPv6 address to a particular value. */
|
---|
115 | #define ip6_addr_set_zone(ip6addr, zone_idx) ((ip6addr)->zone = (zone_idx))
|
---|
116 |
|
---|
117 | /** Clear the zone field of an IPv6 address, setting it to "no zone". */
|
---|
118 | #define ip6_addr_clear_zone(ip6addr) ((ip6addr)->zone = IP6_NO_ZONE)
|
---|
119 |
|
---|
120 | /** Copy the zone field from the second IPv6 address to the first one. */
|
---|
121 | #define ip6_addr_copy_zone(ip6addr1, ip6addr2) ((ip6addr1).zone = (ip6addr2).zone)
|
---|
122 |
|
---|
123 | /** Is the zone field of the given IPv6 address equal to the given zone index? (0/1) */
|
---|
124 | #define ip6_addr_equals_zone(ip6addr, zone_idx) ((ip6addr)->zone == (zone_idx))
|
---|
125 |
|
---|
126 | /** Are the zone fields of the given IPv6 addresses equal? (0/1)
|
---|
127 | * This macro must only be used on IPv6 addresses of the same scope. */
|
---|
128 | #define ip6_addr_cmp_zone(ip6addr1, ip6addr2) ((ip6addr1)->zone == (ip6addr2)->zone)
|
---|
129 |
|
---|
130 | /** Symbolic constants for the 'type' parameters in some of the macros.
|
---|
131 | * These exist for efficiency only, allowing the macros to avoid certain tests
|
---|
132 | * when the address is known not to be of a certain type. Dead code elimination
|
---|
133 | * will do the rest. IP6_MULTICAST is supported but currently not optimized.
|
---|
134 | * @see ip6_addr_has_scope, ip6_addr_assign_zone, ip6_addr_lacks_zone.
|
---|
135 | */
|
---|
136 | enum lwip_ipv6_scope_type
|
---|
137 | {
|
---|
138 | /** Unknown */
|
---|
139 | IP6_UNKNOWN = 0,
|
---|
140 | /** Unicast */
|
---|
141 | IP6_UNICAST = 1,
|
---|
142 | /** Multicast */
|
---|
143 | IP6_MULTICAST = 2
|
---|
144 | };
|
---|
145 |
|
---|
146 | /** IPV6_CUSTOM_SCOPES: together, the following three macro definitions,
|
---|
147 | * @ref ip6_addr_has_scope, @ref ip6_addr_assign_zone, and
|
---|
148 | * @ref ip6_addr_test_zone, completely define the lwIP scoping policy.
|
---|
149 | * The definitions below implement the default policy from RFC 4007 Sec. 6.
|
---|
150 | * Should an implementation desire to implement a different policy, it can
|
---|
151 | * define IPV6_CUSTOM_SCOPES to 1 and supply its own definitions for the three
|
---|
152 | * macros instead.
|
---|
153 | */
|
---|
154 | #ifndef IPV6_CUSTOM_SCOPES
|
---|
155 | #define IPV6_CUSTOM_SCOPES 0
|
---|
156 | #endif /* !IPV6_CUSTOM_SCOPES */
|
---|
157 |
|
---|
158 | #if !IPV6_CUSTOM_SCOPES
|
---|
159 |
|
---|
160 | /**
|
---|
161 | * Determine whether an IPv6 address has a constrained scope, and as such is
|
---|
162 | * meaningful only if accompanied by a zone index to identify the scope's zone.
|
---|
163 | * The given address type may be used to eliminate at compile time certain
|
---|
164 | * checks that will evaluate to false at run time anyway.
|
---|
165 | *
|
---|
166 | * This default implementation follows the default model of RFC 4007, where
|
---|
167 | * only interface-local and link-local scopes are defined.
|
---|
168 | *
|
---|
169 | * Even though the unicast loopback address does have an implied link-local
|
---|
170 | * scope, in this implementation it does not have an explicitly assigned zone
|
---|
171 | * index. As such it should not be tested for in this macro.
|
---|
172 | *
|
---|
173 | * @param ip6addr the IPv6 address (const); only its address part is examined.
|
---|
174 | * @param type address type; see @ref lwip_ipv6_scope_type.
|
---|
175 | * @return 1 if the address has a constrained scope, 0 if it does not.
|
---|
176 | */
|
---|
177 | #define ip6_addr_has_scope(ip6addr, type) \
|
---|
178 | (ip6_addr_islinklocal(ip6addr) || (((type) != IP6_UNICAST) && \
|
---|
179 | (ip6_addr_ismulticast_iflocal(ip6addr) || \
|
---|
180 | ip6_addr_ismulticast_linklocal(ip6addr))))
|
---|
181 |
|
---|
182 | /**
|
---|
183 | * Assign a zone index to an IPv6 address, based on a network interface. If the
|
---|
184 | * given address has a scope, the assigned zone index is that scope's zone of
|
---|
185 | * the given netif; otherwise, the assigned zone index is "no zone".
|
---|
186 | *
|
---|
187 | * This default implementation follows the default model of RFC 4007, where
|
---|
188 | * only interface-local and link-local scopes are defined, and the zone index
|
---|
189 | * of both of those scopes always equals the index of the network interface.
|
---|
190 | * As such, this default implementation need not distinguish between different
|
---|
191 | * constrained scopes when assigning the zone.
|
---|
192 | *
|
---|
193 | * @param ip6addr the IPv6 address; its address part is examined, and its zone
|
---|
194 | * index is assigned.
|
---|
195 | * @param type address type; see @ref lwip_ipv6_scope_type.
|
---|
196 | * @param netif the network interface (const).
|
---|
197 | */
|
---|
198 | #define ip6_addr_assign_zone(ip6addr, type, netif) \
|
---|
199 | (ip6_addr_set_zone((ip6addr), \
|
---|
200 | ip6_addr_has_scope((ip6addr), (type)) ? netif_get_index(netif) : 0))
|
---|
201 |
|
---|
202 | /**
|
---|
203 | * Test whether an IPv6 address is "zone-compatible" with a network interface.
|
---|
204 | * That is, test whether the network interface is part of the zone associated
|
---|
205 | * with the address. For efficiency, this macro is only ever called if the
|
---|
206 | * given address is either scoped or zoned, and thus, it need not test this.
|
---|
207 | * If an address is scoped but not zoned, or zoned and not scoped, it is
|
---|
208 | * considered not zone-compatible with any netif.
|
---|
209 | *
|
---|
210 | * This default implementation follows the default model of RFC 4007, where
|
---|
211 | * only interface-local and link-local scopes are defined, and the zone index
|
---|
212 | * of both of those scopes always equals the index of the network interface.
|
---|
213 | * As such, there is always only one matching netif for a specific zone index,
|
---|
214 | * but all call sites of this macro currently support multiple matching netifs
|
---|
215 | * as well (at no additional expense in the common case).
|
---|
216 | *
|
---|
217 | * @param ip6addr the IPv6 address (const).
|
---|
218 | * @param netif the network interface (const).
|
---|
219 | * @return 1 if the address is scope-compatible with the netif, 0 if not.
|
---|
220 | */
|
---|
221 | #define ip6_addr_test_zone(ip6addr, netif) \
|
---|
222 | (ip6_addr_equals_zone((ip6addr), netif_get_index(netif)))
|
---|
223 |
|
---|
224 | #endif /* !IPV6_CUSTOM_SCOPES */
|
---|
225 |
|
---|
226 | /** Does the given IPv6 address have a scope, and as such should also have a
|
---|
227 | * zone to be meaningful, but does not actually have a zone? (0/1) */
|
---|
228 | #define ip6_addr_lacks_zone(ip6addr, type) \
|
---|
229 | (!ip6_addr_has_zone(ip6addr) && ip6_addr_has_scope((ip6addr), (type)))
|
---|
230 |
|
---|
231 | /**
|
---|
232 | * Try to select a zone for a scoped address that does not yet have a zone.
|
---|
233 | * Called from PCB bind and connect routines, for two reasons: 1) to save on
|
---|
234 | * this (relatively expensive) selection for every individual packet route
|
---|
235 | * operation and 2) to allow the application to obtain the selected zone from
|
---|
236 | * the PCB as is customary for e.g. getsockname/getpeername BSD socket calls.
|
---|
237 | *
|
---|
238 | * Ideally, callers would always supply a properly zoned address, in which case
|
---|
239 | * this function would not be needed. It exists both for compatibility with the
|
---|
240 | * BSD socket API (which accepts zoneless destination addresses) and for
|
---|
241 | * backward compatibility with pre-scoping lwIP code.
|
---|
242 | *
|
---|
243 | * It may be impossible to select a zone, e.g. if there are no netifs. In that
|
---|
244 | * case, the address's zone field will be left as is.
|
---|
245 | *
|
---|
246 | * @param dest the IPv6 address for which to select and set a zone.
|
---|
247 | * @param src source IPv6 address (const); may be equal to dest.
|
---|
248 | */
|
---|
249 | #define ip6_addr_select_zone(dest, src) do { struct netif *selected_netif; \
|
---|
250 | selected_netif = ip6_route((src), (dest)); \
|
---|
251 | if (selected_netif != NULL) { \
|
---|
252 | ip6_addr_assign_zone((dest), IP6_UNKNOWN, selected_netif); \
|
---|
253 | } } while (0)
|
---|
254 |
|
---|
255 | /**
|
---|
256 | * @}
|
---|
257 | */
|
---|
258 |
|
---|
259 | #else /* LWIP_IPV6_SCOPES */
|
---|
260 |
|
---|
261 | #define IPADDR6_ZONE_INIT
|
---|
262 | #define ip6_addr_zone(ip6addr) (IP6_NO_ZONE)
|
---|
263 | #define ip6_addr_has_zone(ip6addr) (0)
|
---|
264 | #define ip6_addr_set_zone(ip6addr, zone_idx)
|
---|
265 | #define ip6_addr_clear_zone(ip6addr)
|
---|
266 | #define ip6_addr_copy_zone(ip6addr1, ip6addr2)
|
---|
267 | #define ip6_addr_equals_zone(ip6addr, zone_idx) (1)
|
---|
268 | #define ip6_addr_cmp_zone(ip6addr1, ip6addr2) (1)
|
---|
269 | #define IPV6_CUSTOM_SCOPES 0
|
---|
270 | #define ip6_addr_has_scope(ip6addr, type) (0)
|
---|
271 | #define ip6_addr_assign_zone(ip6addr, type, netif)
|
---|
272 | #define ip6_addr_test_zone(ip6addr, netif) (1)
|
---|
273 | #define ip6_addr_lacks_zone(ip6addr, type) (0)
|
---|
274 | #define ip6_addr_select_zone(ip6addr, src)
|
---|
275 |
|
---|
276 | #endif /* LWIP_IPV6_SCOPES */
|
---|
277 |
|
---|
278 | #if LWIP_IPV6_SCOPES && LWIP_IPV6_SCOPES_DEBUG
|
---|
279 |
|
---|
280 | /** Verify that the given IPv6 address is properly zoned. */
|
---|
281 | #define IP6_ADDR_ZONECHECK(ip6addr) LWIP_ASSERT("IPv6 zone check failed", \
|
---|
282 | ip6_addr_has_scope(ip6addr, IP6_UNKNOWN) == ip6_addr_has_zone(ip6addr))
|
---|
283 |
|
---|
284 | /** Verify that the given IPv6 address is properly zoned for the given netif. */
|
---|
285 | #define IP6_ADDR_ZONECHECK_NETIF(ip6addr, netif) LWIP_ASSERT("IPv6 netif zone check failed", \
|
---|
286 | ip6_addr_has_scope(ip6addr, IP6_UNKNOWN) ? \
|
---|
287 | (ip6_addr_has_zone(ip6addr) && \
|
---|
288 | (((netif) == NULL) || ip6_addr_test_zone((ip6addr), (netif)))) : \
|
---|
289 | !ip6_addr_has_zone(ip6addr))
|
---|
290 |
|
---|
291 | #else /* LWIP_IPV6_SCOPES && LWIP_IPV6_SCOPES_DEBUG */
|
---|
292 |
|
---|
293 | #define IP6_ADDR_ZONECHECK(ip6addr)
|
---|
294 | #define IP6_ADDR_ZONECHECK_NETIF(ip6addr, netif)
|
---|
295 |
|
---|
296 | #endif /* LWIP_IPV6_SCOPES && LWIP_IPV6_SCOPES_DEBUG */
|
---|
297 |
|
---|
298 | #endif /* LWIP_IPV6 */
|
---|
299 |
|
---|
300 | #ifdef __cplusplus
|
---|
301 | }
|
---|
302 | #endif
|
---|
303 |
|
---|
304 | #endif /* LWIP_HDR_IP6_ZONE_H */
|
---|