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Diffstat (limited to 'lwip/src/include/lwip/ip6_zone.h')
-rw-r--r-- | lwip/src/include/lwip/ip6_zone.h | 304 |
1 files changed, 304 insertions, 0 deletions
diff --git a/lwip/src/include/lwip/ip6_zone.h b/lwip/src/include/lwip/ip6_zone.h new file mode 100644 index 0000000..525790e --- /dev/null +++ b/lwip/src/include/lwip/ip6_zone.h @@ -0,0 +1,304 @@ +/** + * @file + * + * IPv6 address scopes, zones, and scoping policy. + * + * This header provides the means to implement support for IPv6 address scopes, + * as per RFC 4007. An address scope can be either global or more constrained. + * In lwIP, we say that an address "has a scope" or "is scoped" when its scope + * is constrained, in which case the address is meaningful only in a specific + * "zone." For unicast addresses, only link-local addresses have a scope; in + * that case, the scope is the link. For multicast addresses, there are various + * scopes defined by RFC 4007 and others. For any constrained scope, a system + * must establish a (potentially one-to-many) mapping between zones and local + * interfaces. For example, a link-local address is valid on only one link (its + * zone). That link may be attached to one or more local interfaces. The + * decisions on which scopes are constrained and the mapping between zones and + * interfaces is together what we refer to as the "scoping policy" - more on + * this in a bit. + * + * In lwIP, each IPv6 address has an associated zone index. This zone index may + * be set to "no zone" (IP6_NO_ZONE, 0) or an actual zone. We say that an + * address "has a zone" or "is zoned" when its zone index is *not* set to "no + * zone." In lwIP, in principle, each address should be "properly zoned," which + * means that if the address has a zone if and only if has a scope. As such, it + * is a rule that an unscoped (e.g., global) address must never have a zone. + * Even though one could argue that there is always one zone even for global + * scopes, this rule exists for implementation simplicity. Violation of the + * rule will trigger assertions or otherwise result in undesired behavior. + * + * Backward compatibility prevents us from requiring that applications always + * provide properly zoned addresses. We do enforce the rule that the in the + * lwIP link layer (everything below netif->output_ip6() and in particular ND6) + * *all* addresses are properly zoned. Thus, on the output paths down the + * stack, various places deal with the case of addresses that lack a zone. + * Some of them are best-effort for efficiency (e.g. the PCB bind and connect + * API calls' attempts to add missing zones); ultimately the IPv6 output + * handler (@ref ip6_output_if_src) will set a zone if necessary. + * + * Aside from dealing with scoped addresses lacking a zone, a proper IPv6 + * implementation must also ensure that a packet with a scoped source and/or + * destination address does not leave its zone. This is currently implemented + * in the input and forward functions. However, for output, these checks are + * deliberately omitted in order to keep the implementation lightweight. The + * routing algorithm in @ref ip6_route will take decisions such that it will + * not cause zone violations unless the application sets bad addresses, though. + * + * In terms of scoping policy, lwIP implements the default policy from RFC 4007 + * using macros in this file. This policy considers link-local unicast + * addresses and (only) interface-local and link-local multicast addresses as + * having a scope. For all these addresses, the zone is equal to the interface. + * As shown below in this file, it is possible to implement a custom policy. + */ + +/* + * Copyright (c) 2017 The MINIX 3 Project. + * 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. + * + * This file is part of the lwIP TCP/IP stack. + * + * Author: David van Moolenbroek <david@minix3.org> + * + */ +#ifndef LWIP_HDR_IP6_ZONE_H +#define LWIP_HDR_IP6_ZONE_H + +#ifdef __cplusplus +extern "C" { +#endif + +/** + * @defgroup ip6_zones IPv6 Zones + * @ingroup ip6 + * @{ + */ + +#if LWIP_IPV6 /* don't build if not configured for use in lwipopts.h */ + +/** Identifier for "no zone". */ +#define IP6_NO_ZONE 0 + +#if LWIP_IPV6_SCOPES + +/** Zone initializer for static IPv6 address initialization, including comma. */ +#define IPADDR6_ZONE_INIT , IP6_NO_ZONE + +/** Return the zone index of the given IPv6 address; possibly "no zone". */ +#define ip6_addr_zone(ip6addr) ((ip6addr)->zone) + +/** Does the given IPv6 address have a zone set? (0/1) */ +#define ip6_addr_has_zone(ip6addr) (ip6_addr_zone(ip6addr) != IP6_NO_ZONE) + +/** Set the zone field of an IPv6 address to a particular value. */ +#define ip6_addr_set_zone(ip6addr, zone_idx) ((ip6addr)->zone = (zone_idx)) + +/** Clear the zone field of an IPv6 address, setting it to "no zone". */ +#define ip6_addr_clear_zone(ip6addr) ((ip6addr)->zone = IP6_NO_ZONE) + +/** Copy the zone field from the second IPv6 address to the first one. */ +#define ip6_addr_copy_zone(ip6addr1, ip6addr2) ((ip6addr1).zone = (ip6addr2).zone) + +/** Is the zone field of the given IPv6 address equal to the given zone index? (0/1) */ +#define ip6_addr_equals_zone(ip6addr, zone_idx) ((ip6addr)->zone == (zone_idx)) + +/** Are the zone fields of the given IPv6 addresses equal? (0/1) + * This macro must only be used on IPv6 addresses of the same scope. */ +#define ip6_addr_cmp_zone(ip6addr1, ip6addr2) ((ip6addr1)->zone == (ip6addr2)->zone) + +/** Symbolic constants for the 'type' parameters in some of the macros. + * These exist for efficiency only, allowing the macros to avoid certain tests + * when the address is known not to be of a certain type. Dead code elimination + * will do the rest. IP6_MULTICAST is supported but currently not optimized. + * @see ip6_addr_has_scope, ip6_addr_assign_zone, ip6_addr_lacks_zone. + */ +enum lwip_ipv6_scope_type +{ + /** Unknown */ + IP6_UNKNOWN = 0, + /** Unicast */ + IP6_UNICAST = 1, + /** Multicast */ + IP6_MULTICAST = 2 +}; + +/** IPV6_CUSTOM_SCOPES: together, the following three macro definitions, + * @ref ip6_addr_has_scope, @ref ip6_addr_assign_zone, and + * @ref ip6_addr_test_zone, completely define the lwIP scoping policy. + * The definitions below implement the default policy from RFC 4007 Sec. 6. + * Should an implementation desire to implement a different policy, it can + * define IPV6_CUSTOM_SCOPES to 1 and supply its own definitions for the three + * macros instead. + */ +#ifndef IPV6_CUSTOM_SCOPES +#define IPV6_CUSTOM_SCOPES 0 +#endif /* !IPV6_CUSTOM_SCOPES */ + +#if !IPV6_CUSTOM_SCOPES + +/** + * Determine whether an IPv6 address has a constrained scope, and as such is + * meaningful only if accompanied by a zone index to identify the scope's zone. + * The given address type may be used to eliminate at compile time certain + * checks that will evaluate to false at run time anyway. + * + * This default implementation follows the default model of RFC 4007, where + * only interface-local and link-local scopes are defined. + * + * Even though the unicast loopback address does have an implied link-local + * scope, in this implementation it does not have an explicitly assigned zone + * index. As such it should not be tested for in this macro. + * + * @param ip6addr the IPv6 address (const); only its address part is examined. + * @param type address type; see @ref lwip_ipv6_scope_type. + * @return 1 if the address has a constrained scope, 0 if it does not. + */ +#define ip6_addr_has_scope(ip6addr, type) \ + (ip6_addr_islinklocal(ip6addr) || (((type) != IP6_UNICAST) && \ + (ip6_addr_ismulticast_iflocal(ip6addr) || \ + ip6_addr_ismulticast_linklocal(ip6addr)))) + +/** + * Assign a zone index to an IPv6 address, based on a network interface. If the + * given address has a scope, the assigned zone index is that scope's zone of + * the given netif; otherwise, the assigned zone index is "no zone". + * + * This default implementation follows the default model of RFC 4007, where + * only interface-local and link-local scopes are defined, and the zone index + * of both of those scopes always equals the index of the network interface. + * As such, this default implementation need not distinguish between different + * constrained scopes when assigning the zone. + * + * @param ip6addr the IPv6 address; its address part is examined, and its zone + * index is assigned. + * @param type address type; see @ref lwip_ipv6_scope_type. + * @param netif the network interface (const). + */ +#define ip6_addr_assign_zone(ip6addr, type, netif) \ + (ip6_addr_set_zone((ip6addr), \ + ip6_addr_has_scope((ip6addr), (type)) ? netif_get_index(netif) : 0)) + +/** + * Test whether an IPv6 address is "zone-compatible" with a network interface. + * That is, test whether the network interface is part of the zone associated + * with the address. For efficiency, this macro is only ever called if the + * given address is either scoped or zoned, and thus, it need not test this. + * If an address is scoped but not zoned, or zoned and not scoped, it is + * considered not zone-compatible with any netif. + * + * This default implementation follows the default model of RFC 4007, where + * only interface-local and link-local scopes are defined, and the zone index + * of both of those scopes always equals the index of the network interface. + * As such, there is always only one matching netif for a specific zone index, + * but all call sites of this macro currently support multiple matching netifs + * as well (at no additional expense in the common case). + * + * @param ip6addr the IPv6 address (const). + * @param netif the network interface (const). + * @return 1 if the address is scope-compatible with the netif, 0 if not. + */ +#define ip6_addr_test_zone(ip6addr, netif) \ + (ip6_addr_equals_zone((ip6addr), netif_get_index(netif))) + +#endif /* !IPV6_CUSTOM_SCOPES */ + +/** Does the given IPv6 address have a scope, and as such should also have a + * zone to be meaningful, but does not actually have a zone? (0/1) */ +#define ip6_addr_lacks_zone(ip6addr, type) \ + (!ip6_addr_has_zone(ip6addr) && ip6_addr_has_scope((ip6addr), (type))) + +/** + * Try to select a zone for a scoped address that does not yet have a zone. + * Called from PCB bind and connect routines, for two reasons: 1) to save on + * this (relatively expensive) selection for every individual packet route + * operation and 2) to allow the application to obtain the selected zone from + * the PCB as is customary for e.g. getsockname/getpeername BSD socket calls. + * + * Ideally, callers would always supply a properly zoned address, in which case + * this function would not be needed. It exists both for compatibility with the + * BSD socket API (which accepts zoneless destination addresses) and for + * backward compatibility with pre-scoping lwIP code. + * + * It may be impossible to select a zone, e.g. if there are no netifs. In that + * case, the address's zone field will be left as is. + * + * @param dest the IPv6 address for which to select and set a zone. + * @param src source IPv6 address (const); may be equal to dest. + */ +#define ip6_addr_select_zone(dest, src) do { struct netif *selected_netif; \ + selected_netif = ip6_route((src), (dest)); \ + if (selected_netif != NULL) { \ + ip6_addr_assign_zone((dest), IP6_UNKNOWN, selected_netif); \ + } } while (0) + +/** + * @} + */ + +#else /* LWIP_IPV6_SCOPES */ + +#define IPADDR6_ZONE_INIT +#define ip6_addr_zone(ip6addr) (IP6_NO_ZONE) +#define ip6_addr_has_zone(ip6addr) (0) +#define ip6_addr_set_zone(ip6addr, zone_idx) +#define ip6_addr_clear_zone(ip6addr) +#define ip6_addr_copy_zone(ip6addr1, ip6addr2) +#define ip6_addr_equals_zone(ip6addr, zone_idx) (1) +#define ip6_addr_cmp_zone(ip6addr1, ip6addr2) (1) +#define IPV6_CUSTOM_SCOPES 0 +#define ip6_addr_has_scope(ip6addr, type) (0) +#define ip6_addr_assign_zone(ip6addr, type, netif) +#define ip6_addr_test_zone(ip6addr, netif) (1) +#define ip6_addr_lacks_zone(ip6addr, type) (0) +#define ip6_addr_select_zone(ip6addr, src) + +#endif /* LWIP_IPV6_SCOPES */ + +#if LWIP_IPV6_SCOPES && LWIP_IPV6_SCOPES_DEBUG + +/** Verify that the given IPv6 address is properly zoned. */ +#define IP6_ADDR_ZONECHECK(ip6addr) LWIP_ASSERT("IPv6 zone check failed", \ + ip6_addr_has_scope(ip6addr, IP6_UNKNOWN) == ip6_addr_has_zone(ip6addr)) + +/** Verify that the given IPv6 address is properly zoned for the given netif. */ +#define IP6_ADDR_ZONECHECK_NETIF(ip6addr, netif) LWIP_ASSERT("IPv6 netif zone check failed", \ + ip6_addr_has_scope(ip6addr, IP6_UNKNOWN) ? \ + (ip6_addr_has_zone(ip6addr) && \ + (((netif) == NULL) || ip6_addr_test_zone((ip6addr), (netif)))) : \ + !ip6_addr_has_zone(ip6addr)) + +#else /* LWIP_IPV6_SCOPES && LWIP_IPV6_SCOPES_DEBUG */ + +#define IP6_ADDR_ZONECHECK(ip6addr) +#define IP6_ADDR_ZONECHECK_NETIF(ip6addr, netif) + +#endif /* LWIP_IPV6_SCOPES && LWIP_IPV6_SCOPES_DEBUG */ + +#endif /* LWIP_IPV6 */ + +#ifdef __cplusplus +} +#endif + +#endif /* LWIP_HDR_IP6_ZONE_H */ |