/* $OpenBSD: rde_trie.c,v 1.14 2022/02/06 09:51:19 claudio Exp $ */ /* * Copyright (c) 2018 Claudio Jeker * * Permission to use, copy, modify, and distribute this software for any * purpose with or without fee is hereby granted, provided that the above * copyright notice and this permission notice appear in all copies. * * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ #include #include #include #include #include #include #include "bgpd.h" #include "rde.h" /* * Bitwise compressed trie for prefix-sets. * Since the trie is path compressed the traversing function needs to check * that the lookup is still on path before taking a branch. * There are two types of nodes in the trie. Internal branch nodes and real * nodes. Internal nodes are added when needed because off path nodes are being * inserted and are just used for branching. * During lookup every node defines which bit is checked for branching. This * offset is strictly increasing. For IPv4 the maximum is therefor 32 levels. * Every node checks the bit at position plen to decide which branch to take. * The real nodes also include a prefixlen mask which represents the prefixlen * range that was defined. The prefixlen mask for IPv4 only has 32 bits but * the prefixlen range is from 0 - 32 which needs 33bits. Now prefixlen 0 is * special and only one element -- the default route -- can have prefixlen 0. * So this default route is added as a flag to the trie_head and needs to be * checked independent of the trie when doing a lookup. * On insertion a prefix is added with its prefixlen plen and a min & max * for the prefixlen range. The following precondition needs to hold * plen <= min <= max * To only match the prefix itself min and max are set to plen. * If a same prefix (addr/plen) is added to the trie but with different * min & max values then the masks of both nodes are merged with a binary OR. * The match function returns true the moment the first node is found which * covers the looked up prefix and where the prefixlen mask matches for the * looked up prefixlen. The moment the plen of a node is bigger than the * prefixlen of the looked up prefix the search can be stopped since * there will be no match. */ struct tentry_v4 { struct tentry_v4 *trie[2]; struct set_table *set; /* for roa source-as set */ struct in_addr addr; struct in_addr plenmask; uint8_t plen; uint8_t node; }; struct tentry_v6 { struct tentry_v6 *trie[2]; struct set_table *set; /* for roa source-as set */ struct in6_addr addr; struct in6_addr plenmask; uint8_t plen; uint8_t node; }; /* * Find first different bit between a & b starting from the MSB, * a & b have to be different. */ static int inet4findmsb(struct in_addr *a, struct in_addr *b) { int r = 0; uint32_t v; v = ntohl(a->s_addr ^ b->s_addr); if (v > 0xffff) { r += 16; v >>= 16; } if (v > 0x00ff) { r += 8; v >>= 8; } if (v > 0x000f) { r += 4; v >>= 4; } if (v > 0x0003) { r += 2; v >>= 2; } if (v > 0x0001) { r += 1; } return 31 - r; } /* * Find first different bit between a & b starting from the MSB, * a & b have to be different. */ static int inet6findmsb(struct in6_addr *a, struct in6_addr *b) { int r = 0; uint8_t i, x; for (i = 0; i < sizeof(*a) && a->s6_addr[i] == b->s6_addr[i]; i++) ; /* first different octet */ x = a->s6_addr[i] ^ b->s6_addr[i]; /* first different bit */ if (x > 0xf) { r += 4; x >>= 4; } if (x > 0x3) { r += 2; x >>= 2; } if (x > 0x1) { r += 1; } return i * 8 + 7 - r; } static int inet4isset(struct in_addr *addr, uint8_t bit) { return addr->s_addr & htonl(1U << (31 - bit)); } static int inet6isset(struct in6_addr *addr, uint8_t bit) { return addr->s6_addr[bit / 8] & (0x80 >> (bit % 8)); } static void inet4setbit(struct in_addr *addr, uint8_t bit) { /* bit 0 sets the MSB and 31 sets the LSB */ addr->s_addr |= htonl(1U << (31 - bit)); } static void inet6setbit(struct in6_addr *addr, uint8_t bit) { addr->s6_addr[bit / 8] |= (0x80 >> (bit % 8)); } static struct tentry_v4 * trie_add_v4(struct trie_head *th, struct in_addr *prefix, uint8_t plen) { struct tentry_v4 *n, *new, *b, **prev; struct in_addr p; inet4applymask(&p, prefix, plen); /* walk tree finding spot to insert */ prev = &th->root_v4; n = *prev; while (n) { struct in_addr mp; uint8_t minlen; minlen = n->plen > plen ? plen : n->plen; inet4applymask(&mp, &p, minlen); if (n->addr.s_addr != mp.s_addr) { /* * out of path, insert intermediary node between * np and n, then insert n and new node there */ if ((b = calloc(1, sizeof(*b))) == NULL) return NULL; rdemem.pset_cnt++; rdemem.pset_size += sizeof(*b); b->plen = inet4findmsb(&n->addr, &mp); inet4applymask(&b->addr, &n->addr, b->plen); *prev = b; if (inet4isset(&n->addr, b->plen)) { b->trie[1] = n; prev = &b->trie[0]; } else { b->trie[0] = n; prev = &b->trie[1]; } n = NULL; break; } if (n->plen > plen) { /* n is more specific, just insert new in between */ break; } if (n->plen == plen) { /* matching node, adjust */ if (n->node == 0) th->v4_cnt++; n->node = 1; return n; } /* no need to check for n->plen == 32 because of above if */ if (inet4isset(&p, n->plen)) prev = &n->trie[1]; else prev = &n->trie[0]; n = *prev; } /* create new node */ if ((new = calloc(1, sizeof(*new))) == NULL) return NULL; th->v4_cnt++; rdemem.pset_cnt++; rdemem.pset_size += sizeof(*new); new->addr = p; new->plen = plen; new->node = 1; /* link node */ *prev = new; if (n) { if (inet4isset(&n->addr, new->plen)) new->trie[1] = n; else new->trie[0] = n; } return new; } static struct tentry_v6 * trie_add_v6(struct trie_head *th, struct in6_addr *prefix, uint8_t plen) { struct tentry_v6 *n, *new, *b, **prev; struct in6_addr p; inet6applymask(&p, prefix, plen); /* walk tree finding spot to insert */ prev = &th->root_v6; n = *prev; while (n) { struct in6_addr mp; uint8_t minlen; minlen = n->plen > plen ? plen : n->plen; inet6applymask(&mp, &p, minlen); if (memcmp(&n->addr, &mp, sizeof(mp)) != 0) { /* * out of path, insert intermediary node between * np and n, then insert n and new node there */ if ((b = calloc(1, sizeof(*b))) == NULL) return NULL; rdemem.pset_cnt++; rdemem.pset_size += sizeof(*b); b->plen = inet6findmsb(&n->addr, &mp); inet6applymask(&b->addr, &n->addr, b->plen); *prev = b; if (inet6isset(&n->addr, b->plen)) { b->trie[1] = n; prev = &b->trie[0]; } else { b->trie[0] = n; prev = &b->trie[1]; } n = NULL; break; } if (n->plen > plen) { /* n is more specific, just insert new in between */ break; } if (n->plen == plen) { /* matching node, adjust */ if (n->node == 0) th->v6_cnt++; n->node = 1; return n; } /* no need to check for n->plen == 128 because of above if */ if (inet6isset(&p, n->plen)) prev = &n->trie[1]; else prev = &n->trie[0]; n = *prev; } /* create new node */ if ((new = calloc(1, sizeof(*new))) == NULL) return NULL; th->v6_cnt++; rdemem.pset_cnt++; rdemem.pset_size += sizeof(*new); new->addr = p; new->plen = plen; new->node = 1; /* link node */ *prev = new; if (n) { if (inet6isset(&n->addr, new->plen)) new->trie[1] = n; else new->trie[0] = n; } return new; } /* * Insert prefix/plen into the trie with a prefixlen mask covering min - max. * If plen == min == max then only the prefix/plen will match and no longer * match is possible. Else all prefixes under prefix/plen with a prefixlen * between min and max will match. */ int trie_add(struct trie_head *th, struct bgpd_addr *prefix, uint8_t plen, uint8_t min, uint8_t max) { struct tentry_v4 *n4; struct tentry_v6 *n6; uint8_t i; /* precondition plen <= min <= max */ if (plen > min || min > max) return -1; if (prefix->aid != AID_INET && prefix->aid != AID_INET6) return -1; /* * Check for default route, this is special cased since prefixlen 0 * can't be checked in the prefixlen mask plenmask. Also there is * only one default route so using a flag for this works. */ if (min == 0) { if (prefix->aid == AID_INET) th->match_default_v4 = 1; else th->match_default_v6 = 1; if (max == 0) /* just the default route */ return 0; min = 1; } switch (prefix->aid) { case AID_INET: if (max > 32) return -1; n4 = trie_add_v4(th, &prefix->v4, plen); if (n4 == NULL) return -1; /* * The prefixlen min - max goes from 1 to 32 but the bitmask * starts at 0 and so all bits are set with an offset of -1. * The default /0 route is handled specially above. */ for (i = min; i <= max; i++) inet4setbit(&n4->plenmask, i - 1); break; case AID_INET6: if (max > 128) return -1; n6 = trie_add_v6(th, &prefix->v6, plen); if (n6 == NULL) return -1; /* See above for the - 1 reason. */ for (i = min; i <= max; i++) inet6setbit(&n6->plenmask, i - 1); break; } return 0; } /* * Insert a ROA entry for prefix/plen. The prefix will insert a set with * source_as and the maxlen as data. This makes it possible to validate if a * prefix is matching this ROA record. It is possible to insert prefixes with * source_as = 0. These entries will never return ROA_VALID on check and can * be used to cover a large prefix as ROA_INVALID unless a more specific route * is a match. */ int trie_roa_add(struct trie_head *th, struct roa *roa) { struct tentry_v4 *n4; struct tentry_v6 *n6; struct set_table **stp; struct roa_set rs, *rsp; /* ignore possible default route since it does not make sense */ switch (roa->aid) { case AID_INET: if (roa->prefixlen > 32) return -1; n4 = trie_add_v4(th, &roa->prefix.inet, roa->prefixlen); if (n4 == NULL) return -1; stp = &n4->set; break; case AID_INET6: if (roa->prefixlen > 128) return -1; n6 = trie_add_v6(th, &roa->prefix.inet6, roa->prefixlen); if (n6 == NULL) return -1; stp = &n6->set; break; default: /* anything else fails */ return -1; } if (*stp == NULL) if ((*stp = set_new(1, sizeof(rs))) == NULL) return -1; /* merge sets with same key, longer maxlen wins */ if ((rsp = set_match(*stp, roa->asnum)) != NULL) { if (rsp->maxlen < roa->maxlen) rsp->maxlen = roa->maxlen; } else { rs.as = roa->asnum; rs.maxlen = roa->maxlen; if (set_add(*stp, &rs, 1) != 0) return -1; /* prep data so that set_match works */ set_prep(*stp); } return 0; } static void trie_free_v4(struct tentry_v4 *n) { if (n == NULL) return; trie_free_v4(n->trie[0]); trie_free_v4(n->trie[1]); set_free(n->set); free(n); rdemem.pset_cnt--; rdemem.pset_size -= sizeof(*n); } static void trie_free_v6(struct tentry_v6 *n) { if (n == NULL) return; trie_free_v6(n->trie[0]); trie_free_v6(n->trie[1]); set_free(n->set); free(n); rdemem.pset_cnt--; rdemem.pset_size -= sizeof(*n); } void trie_free(struct trie_head *th) { trie_free_v4(th->root_v4); trie_free_v6(th->root_v6); } static int trie_match_v4(struct trie_head *th, struct in_addr *prefix, uint8_t plen, int orlonger) { struct tentry_v4 *n; if (plen == 0) { /* special handling for default route */ return th->match_default_v4; } n = th->root_v4; while (n) { struct in_addr mp; if (n->plen > plen) break; /* too specific, no match possible */ inet4applymask(&mp, prefix, n->plen); if (n->addr.s_addr != mp.s_addr) break; /* off path, no match possible */ /* the match covers all larger prefixlens */ if (n->node && orlonger) return 1; /* plen is from 1 - 32 but the bitmask starts with 0 */ if (n->node && inet4isset(&n->plenmask, plen - 1)) return 1; /* prefixlen allowed, match */ if (n->plen == 32) break; /* can't go deeper */ if (inet4isset(prefix, n->plen)) n = n->trie[1]; else n = n->trie[0]; } return 0; } static int trie_match_v6(struct trie_head *th, struct in6_addr *prefix, uint8_t plen, int orlonger) { struct tentry_v6 *n; if (plen == 0) { /* special handling for default route */ return th->match_default_v6; } n = th->root_v6; while (n) { struct in6_addr mp; if (n->plen > plen) break; /* too specific, no match possible */ inet6applymask(&mp, prefix, n->plen); if (memcmp(&n->addr, &mp, sizeof(mp)) != 0) break; /* off path, no match possible */ /* the match covers all larger prefixlens */ if (n->node && orlonger) return 1; /* plen is from 1 - 128 but the bitmask starts with 0 */ if (n->node && inet6isset(&n->plenmask, plen - 1)) return 1; /* prefixlen allowed, match */ if (n->plen == 128) break; /* can't go deeper */ if (inet6isset(prefix, n->plen)) n = n->trie[1]; else n = n->trie[0]; } return 0; } /* find first matching element in the trie for prefix "prefix/plen" */ int trie_match(struct trie_head *th, struct bgpd_addr *prefix, uint8_t plen, int orlonger) { switch (prefix->aid) { case AID_INET: return trie_match_v4(th, &prefix->v4, plen, orlonger); case AID_INET6: return trie_match_v6(th, &prefix->v6, plen, orlonger); default: /* anything else is no match */ return 0; } } static int trie_roa_check_v4(struct trie_head *th, struct in_addr *prefix, uint8_t plen, uint32_t as) { struct tentry_v4 *n; struct roa_set *rs; int validity = ROA_NOTFOUND; /* ignore possible default route since it does not make sense */ n = th->root_v4; while (n) { struct in_addr mp; if (n->plen > plen) break; /* too specific, no match possible */ inet4applymask(&mp, prefix, n->plen); if (n->addr.s_addr != mp.s_addr) break; /* off path, no other match possible */ if (n->node) { /* * The prefix is covered by this roa node * therefor invalid unless roa_set matches. */ validity = ROA_INVALID; /* AS_NONE can never match, so don't try */ if (as != AS_NONE) { if ((rs = set_match(n->set, as)) != NULL) { if (plen == n->plen || plen <= rs->maxlen) return ROA_VALID; } } } if (n->plen == 32) break; /* can't go deeper */ if (inet4isset(prefix, n->plen)) n = n->trie[1]; else n = n->trie[0]; } return validity; } static int trie_roa_check_v6(struct trie_head *th, struct in6_addr *prefix, uint8_t plen, uint32_t as) { struct tentry_v6 *n; struct roa_set *rs; int validity = ROA_NOTFOUND; /* ignore possible default route since it does not make sense */ n = th->root_v6; while (n) { struct in6_addr mp; if (n->plen > plen) break; /* too specific, no match possible */ inet6applymask(&mp, prefix, n->plen); if (memcmp(&n->addr, &mp, sizeof(mp)) != 0) break; /* off path, no other match possible */ if (n->node) { /* * This prefix is covered by this roa node. * Therefor invalid unless proven otherwise. */ validity = ROA_INVALID; /* AS_NONE can never match, so don't try */ if (as != AS_NONE) { if ((rs = set_match(n->set, as)) != NULL) if (plen == n->plen || plen <= rs->maxlen) return ROA_VALID; } } if (n->plen == 128) break; /* can't go deeper */ if (inet6isset(prefix, n->plen)) n = n->trie[1]; else n = n->trie[0]; } return validity; } /* * Do a ROA (Route Origin Validation) check. Look for elements in the trie * which cover prefix "prefix/plen" and match the source-as as. * AS_NONE can be used when the source-as is unknown (e.g. AS_SET). * The check will then only return ROA_NOTFOUND or ROA_INVALID depending if * the prefix is covered by the ROA. */ int trie_roa_check(struct trie_head *th, struct bgpd_addr *prefix, uint8_t plen, uint32_t as) { /* valid, invalid, unknown */ switch (prefix->aid) { case AID_INET: return trie_roa_check_v4(th, &prefix->v4, plen, as); case AID_INET6: return trie_roa_check_v6(th, &prefix->v6, plen, as); default: /* anything else is not-found */ return ROA_NOTFOUND; } } static int trie_equal_v4(struct tentry_v4 *a, struct tentry_v4 *b) { if (a == NULL && b == NULL) return 1; if (a == NULL || b == NULL) return 0; if (a->addr.s_addr != b->addr.s_addr || a->plen != b->plen || a->node != b->node || a->plenmask.s_addr != b->plenmask.s_addr) return 0; if (set_equal(a->set, b->set) == 0) return 0; if (trie_equal_v4(a->trie[0], b->trie[0]) == 0 || trie_equal_v4(a->trie[1], b->trie[1]) == 0) return 0; return 1; } static int trie_equal_v6(struct tentry_v6 *a, struct tentry_v6 *b) { if (a == NULL && b == NULL) return 1; if (a == NULL || b == NULL) return 0; if (memcmp(&a->addr, &b->addr, sizeof(a->addr)) != 0 || a->plen != b->plen || a->node != b->node || memcmp(&a->plenmask, &b->plenmask, sizeof(a->plenmask)) != 0) return 0; if (set_equal(a->set, b->set) == 0) return 0; if (trie_equal_v6(a->trie[0], b->trie[0]) == 0 || trie_equal_v6(a->trie[1], b->trie[1]) == 0) return 0; return 1; } /* Compare two tries and return 1 if they are the same else 0. */ int trie_equal(struct trie_head *a, struct trie_head *b) { if (a->match_default_v4 != b->match_default_v4 || a->match_default_v6 != b->match_default_v6) return 0; if (trie_equal_v4(a->root_v4, b->root_v4) == 0) return 0; if (trie_equal_v6(a->root_v6, b->root_v6) == 0) return 0; return 1; } /* debugging functions for printing the trie */ static void trie_dump_v4(struct tentry_v4 *n) { if (n == NULL) return; if (n->node) fprintf(stderr, "%s/%u plenmask %08x\n", inet_ntoa(n->addr), n->plen, n->plenmask.s_addr); else fprintf(stderr, " %s/%u\n", inet_ntoa(n->addr), n->plen); trie_dump_v4(n->trie[0]); trie_dump_v4(n->trie[1]); } static void trie_dump_v6(struct tentry_v6 *n) { char buf[48]; unsigned int i; if (n == NULL) return; if (n->node) { fprintf(stderr, "%s/%u plenmask ", inet_ntop(AF_INET6, &n->addr, buf, sizeof(buf)), n->plen); for (i = 0; i < sizeof(n->plenmask); i++) fprintf(stderr, "%02x", n->plenmask.s6_addr[i]); fprintf(stderr, "\n"); } else fprintf(stderr, " %s/%u\n", inet_ntop(AF_INET6, &n->addr, buf, sizeof(buf)), n->plen); trie_dump_v6(n->trie[0]); trie_dump_v6(n->trie[1]); } void trie_dump(struct trie_head *th) { if (th->match_default_v4) fprintf(stderr, "0.0.0.0/0 plenmask 0\n"); trie_dump_v4(th->root_v4); if (th->match_default_v6) fprintf(stderr, "::/0 plenmask 0\n"); trie_dump_v6(th->root_v6); }