diff options
| -rw-r--r-- | filter/data.h | 23 | ||||
| -rw-r--r-- | filter/trie.c | 245 | ||||
| -rw-r--r-- | filter/trie_test.c | 158 |
3 files changed, 413 insertions, 13 deletions
diff --git a/filter/data.h b/filter/data.h index 21967deb..4a0ee865 100644 --- a/filter/data.h +++ b/filter/data.h @@ -140,7 +140,8 @@ struct f_tree { void *data; }; -#define TRIE_STEP 4 +#define TRIE_STEP 4 +#define TRIE_STACK_LENGTH 33 struct f_trie_node4 { @@ -175,6 +176,16 @@ struct f_trie struct f_trie_node root; /* Root trie node */ }; +struct f_trie_walk_state +{ + u8 ipv4; + u8 accept_length; /* Current inter-node prefix position */ + u8 start_pos; /* Initial prefix position in stack[0] */ + u8 local_pos; /* Current intra-node prefix position */ + u8 stack_pos; /* Current node in stack below */ + const struct f_trie_node *stack[TRIE_STACK_LENGTH]; +}; + struct f_tree *f_new_tree(void); struct f_tree *build_tree(struct f_tree *); const struct f_tree *find_tree(const struct f_tree *t, const struct f_val *val); @@ -185,9 +196,19 @@ void tree_walk(const struct f_tree *t, void (*hook)(const struct f_tree *, void struct f_trie *f_new_trie(linpool *lp, uint data_size); void *trie_add_prefix(struct f_trie *t, const net_addr *n, uint l, uint h); int trie_match_net(const struct f_trie *t, const net_addr *n); +void trie_walk_init(struct f_trie_walk_state *s, const struct f_trie *t, const net_addr *from); +int trie_walk_next(struct f_trie_walk_state *s, net_addr *net); int trie_same(const struct f_trie *t1, const struct f_trie *t2); void trie_format(const struct f_trie *t, buffer *buf); +#define TRIE_WALK(trie, net, from) ({ \ + net_addr net; \ + struct f_trie_walk_state tws_; \ + trie_walk_init(&tws_, trie, from); \ + while (trie_walk_next(&tws_, &net)) + +#define TRIE_WALK_END }) + #define F_CMP_ERROR 999 const char *f_type_name(enum f_type t); diff --git a/filter/trie.c b/filter/trie.c index 5d9cc952..21b5b5d7 100644 --- a/filter/trie.c +++ b/filter/trie.c @@ -1,8 +1,8 @@ /* * Filters: Trie for prefix sets * - * (c) 2009--2020 Ondrej Zajicek <santiago@crfreenet.org> - * (c) 2009--2020 CZ.NIC z.s.p.o. + * (c) 2009--2021 Ondrej Zajicek <santiago@crfreenet.org> + * (c) 2009--2021 CZ.NIC z.s.p.o. * * Can be freely distributed and used under the terms of the GNU GPL. */ @@ -82,6 +82,24 @@ * - we are still on path and keep walking (node length < &plen) * * The walking code in trie_match_net() is structured according to these cases. + * + * Iteration over prefixes in a trie can be done using TRIE_WALK() macro, or + * directly using trie_walk_init() and trie_walk_next() functions. The second + * approeach allows suspending the iteration and continuing in it later. + * Prefixes are enumerated in the usual lexicographic order and may be + * restricted to a subset of the trie (all subnets of a specified prefix). + * + * Note that the trie walk does not reliably enumerate `implicit' prefixes + * defined by &low and &high fields in prefix patterns, it is supposed to be + * used on tries constructed from `explicit' prefixes (&low == &plen == &high + * in call to trie_add_prefix()). + * + * The trie walk has three basic state variables stored in the struct + * &f_trie_walk_state -- the current node in &stack[stack_pos], &accept_length + * for iteration over inter-node prefixes (non-branching prefixes on compressed + * path between the current node and its parent node, stored in the bitmap + * &accept of the current node) and &local_pos for iteration over intra-node + * prefixes (stored in the bitmap &local). */ #include "nest/bird.h" @@ -224,7 +242,7 @@ trie_amask_to_local(ip_addr px, ip_addr amask, uint nlen) #define ADD_LOCAL(N,X,V) ({ uint v_ = (V); if (X) (N)->v4.local |= v_; else (N)->v6.local |= v_; }) -#define GET_CHILD(N,F,X,I) ((X) ? (struct f_trie_node *) (N)->v4.c[I] : (struct f_trie_node *) (N)->v6.c[I]) +#define GET_CHILD(N,X,I) ((X) ? (struct f_trie_node *) (N)->v4.c[I] : (struct f_trie_node *) (N)->v6.c[I]) static void * @@ -312,7 +330,7 @@ trie_add_node(struct f_trie *t, uint plen, ip_addr px, uint local, uint l, uint /* n->plen < plen and plen <= 32 (128) */ o = n; - n = GET_CHILD(n, c, v4, ipa_getbits(paddr, nlen, TRIE_STEP)); + n = GET_CHILD(n, v4, ipa_getbits(paddr, nlen, TRIE_STEP)); } /* We add new tail node 'a' after node 'o' */ @@ -522,6 +540,225 @@ trie_match_net(const struct f_trie *t, const net_addr *n) } } + +#define SAME_PREFIX(A,B,X,L) ((X) ? ip4_prefix_equal((A)->v4.addr, net4_prefix(B), (L)) : ip6_prefix_equal((A)->v6.addr, net6_prefix(B), (L))) +#define GET_NET_BITS(N,X,A,B) ((X) ? ip4_getbits(net4_prefix(N), (A), (B)) : ip6_getbits(net6_prefix(N), (A), (B))) + +/** + * trie_walk_init + * @s: walk state + * @t: trie + * @net: optional subnet for walk + * + * Initialize walk state for subsequent walk through nodes of the trie @t by + * trie_walk_next(). The argument @net allows to restrict walk to given subnet, + * otherwise full walk over all nodes is used. This is done by finding node at + * or below @net and starting position in it. + */ +void +trie_walk_init(struct f_trie_walk_state *s, const struct f_trie *t, const net_addr *net) +{ + *s = (struct f_trie_walk_state) { + .ipv4 = t->ipv4, + .accept_length = 0, + .start_pos = 1, + .local_pos = 1, + .stack_pos = 0, + .stack[0] = &t->root + }; + + if (!net) + return; + + /* We want to find node of level at least plen */ + int plen = ROUND_DOWN_POW2(net->pxlen, TRIE_STEP); + const struct f_trie_node *n = &t->root; + const int v4 = t->ipv4; + + while (n) + { + int nlen = v4 ? n->v4.plen : n->v6.plen; + + /* We are out of path */ + if (!SAME_PREFIX(n, net, v4, MIN(net->pxlen, nlen))) + break; + + /* We found final node */ + if (nlen >= plen) + { + if (nlen == plen) + { + /* Find proper local_pos, while accept_length is not used */ + int step = net->pxlen - plen; + s->start_pos = s->local_pos = (1u << step) + GET_NET_BITS(net, v4, plen, step); + s->accept_length = plen; + } + else + { + /* Start from pos 1 in local node, but first try accept mask */ + s->accept_length = net->pxlen; + } + + s->stack[0] = n; + return; + } + + /* Choose child */ + n = GET_CHILD(n, v4, GET_NET_BITS(net, v4, nlen, TRIE_STEP)); + } + + s->stack[0] = NULL; + return; +} + +#define GET_ACCEPT_BIT(N,X,B) ((X) ? ip4_getbit((N)->v4.accept, (B)) : ip6_getbit((N)->v6.accept, (B))) +#define GET_LOCAL_BIT(N,X,B) (((X) ? (N)->v4.local : (N)->v6.local) & (1u << (B))) + +/** + * trie_walk_next + * @s: walk state + * @net: return value + * + * Find the next prefix in the trie walk and return it in the buffer @net. + * Prefixes are walked in the usual lexicographic order and may be restricted + * to a subset of the trie during walk setup by trie_walk_init(). Note that the + * trie walk does not iterate reliably over 'implicit' prefixes defined by &low + * and &high fields in prefix patterns, it is supposed to be used on tries + * constructed from 'explicit' prefixes (&low == &plen == &high in call to + * trie_add_prefix()). + * + * Result: 1 if the next prefix was found, 0 for the end of walk. + */ +int +trie_walk_next(struct f_trie_walk_state *s, net_addr *net) +{ + const struct f_trie_node *n = s->stack[s->stack_pos]; + int len = s->accept_length; + int pos = s->local_pos; + int v4 = s->ipv4; + + /* + * The walk has three basic state variables -- n, len and pos. In each node n, + * we first walk superprefixes (by len in &accept bitmask), and then we walk + * internal positions (by pos in &local bitmask). These positions are: + * + * 1 + * 2 3 + * 4 5 6 7 + * 8 9 A B C D E F + * + * We walk them depth-first, including virtual positions 10-1F that are + * equivalent of position 1 in child nodes 0-F. + */ + + if (!n) + { + memset(net, 0, v4 ? sizeof(net_addr_ip4) : sizeof(net_addr_ip6)); + return 0; + } + +next_node:; + /* Current node prefix length */ + int nlen = v4 ? n->v4.plen : n->v6.plen; + + /* First, check for accept prefix */ + for (; len < nlen; len++) + if (GET_ACCEPT_BIT(n, v4, len - 1)) + { + if (v4) + net_fill_ip4(net, ip4_and(n->v4.addr, ip4_mkmask(len)), len); + else + net_fill_ip6(net, ip6_and(n->v6.addr, ip6_mkmask(len)), len); + + s->local_pos = pos; + s->accept_length = len + 1; + return 1; + } + +next_pos: + /* Bottom of this node */ + if (pos >= (1 << TRIE_STEP)) + { + const struct f_trie_node *child = GET_CHILD(n, v4, pos - (1 << TRIE_STEP)); + int dir = 0; + + /* No child node */ + if (!child) + { + /* Step up until return from left child (pos is even) */ + do + { + /* Step up from start node */ + if ((s->stack_pos == 0) && (pos == s->start_pos)) + { + s->stack[0] = NULL; + memset(net, 0, v4 ? sizeof(net_addr_ip4) : sizeof(net_addr_ip6)); + return 0; + } + + /* Top of this node */ + if (pos == 1) + { + ASSERT(s->stack_pos); + const struct f_trie_node *old = n; + + /* Move to parent node */ + s->stack_pos--; + n = s->stack[s->stack_pos]; + nlen = v4 ? n->v4.plen : n->v6.plen; + + pos = v4 ? + ip4_getbits(old->v4.addr, nlen, TRIE_STEP) : + ip6_getbits(old->v6.addr, nlen, TRIE_STEP); + pos += (1 << TRIE_STEP); + len = nlen; + + ASSERT(GET_CHILD(n, v4, pos - (1 << TRIE_STEP)) == old); + } + + /* Step up */ + dir = pos % 2; + pos = pos / 2; + } + while (dir); + + /* Continue with step down to the right child */ + pos = 2 * pos + 1; + goto next_pos; + } + + /* Move to child node */ + pos = 1; + len = nlen + TRIE_STEP; + + s->stack_pos++; + n = s->stack[s->stack_pos] = child; + goto next_node; + } + + /* Check for local prefix */ + if (GET_LOCAL_BIT(n, v4, pos)) + { + /* Convert pos to address of local network */ + int x = (pos >= 2) + (pos >= 4) + (pos >= 8); + int y = pos & ((1u << x) - 1); + + if (v4) + net_fill_ip4(net, !x ? n->v4.addr : ip4_setbits(n->v4.addr, nlen + x - 1, y), nlen + x); + else + net_fill_ip6(net, !x ? n->v6.addr : ip6_setbits(n->v6.addr, nlen + x - 1, y), nlen + x); + + s->local_pos = 2 * pos; + s->accept_length = len; + return 1; + } + + /* Step down */ + pos = 2 * pos; + goto next_pos; +} + + static int trie_node_same4(const struct f_trie_node4 *t1, const struct f_trie_node4 *t2) { diff --git a/filter/trie_test.c b/filter/trie_test.c index 3e8ce84d..bb9a2f26 100644 --- a/filter/trie_test.c +++ b/filter/trie_test.c @@ -45,6 +45,13 @@ get_exp_random(void) return n; } +static int +compare_prefixes(const void *a, const void *b) +{ + return net_compare(&((const struct f_prefix *) a)->net, + &((const struct f_prefix *) b)->net); +} + static inline int matching_ip4_nets(const net_addr_ip4 *a, const net_addr_ip4 *b) { @@ -106,11 +113,15 @@ get_random_net(net_addr *net, int v6) } static void -get_random_prefix(struct f_prefix *px, int v6) +get_random_prefix(struct f_prefix *px, int v6, int tight) { get_random_net(&px->net, v6); - if (bt_random() % 2) + if (tight) + { + px->lo = px->hi = px->net.pxlen; + } + else if (bt_random() % 2) { px->lo = 0; px->hi = px->net.pxlen; @@ -238,7 +249,7 @@ get_outer_net(net_addr *net, const struct f_prefix *src) } static list * -make_random_prefix_list(linpool *lp, int num, int v6) +make_random_prefix_list(linpool *lp, int num, int v6, int tight) { list *prefixes = lp_allocz(lp, sizeof(struct f_prefix_node)); init_list(prefixes); @@ -246,7 +257,7 @@ make_random_prefix_list(linpool *lp, int num, int v6) for (int i = 0; i < num; i++) { struct f_prefix_node *px = lp_allocz(lp, sizeof(struct f_prefix_node)); - get_random_prefix(&px->prefix, v6); + get_random_prefix(&px->prefix, v6, tight); add_tail(prefixes, &px->n); char buf[64]; @@ -429,7 +440,7 @@ t_match_random_net(void) linpool *lp = lp_new_default(&root_pool); for (int round = 0; round < TESTS_NUM; round++) { - list *prefixes = make_random_prefix_list(lp, PREFIXES_NUM, v6); + list *prefixes = make_random_prefix_list(lp, PREFIXES_NUM, v6, 0); struct f_trie *trie = make_trie_from_prefix_list(lp, prefixes); for (int i = 0; i < PREFIX_TESTS_NUM; i++) @@ -457,7 +468,7 @@ t_match_inner_net(void) linpool *lp = lp_new_default(&root_pool); for (int round = 0; round < TESTS_NUM; round++) { - list *prefixes = make_random_prefix_list(lp, PREFIXES_NUM, v6); + list *prefixes = make_random_prefix_list(lp, PREFIXES_NUM, v6, 0); struct f_trie *trie = make_trie_from_prefix_list(lp, prefixes); struct f_prefix_node *n = HEAD(*prefixes); @@ -488,7 +499,7 @@ t_match_outer_net(void) linpool *lp = lp_new_default(&root_pool); for (int round = 0; round < TESTS_NUM; round++) { - list *prefixes = make_random_prefix_list(lp, PREFIXES_NUM, v6); + list *prefixes = make_random_prefix_list(lp, PREFIXES_NUM, v6, 0); struct f_trie *trie = make_trie_from_prefix_list(lp, prefixes); struct f_prefix_node *n = HEAD(*prefixes); @@ -613,7 +624,7 @@ t_trie_same(void) linpool *lp = lp_new_default(&root_pool); for (int round = 0; round < TESTS_NUM*4; round++) { - list *prefixes = make_random_prefix_list(lp, 100 * PREFIXES_NUM, v6); + list *prefixes = make_random_prefix_list(lp, 100 * PREFIXES_NUM, v6, 0); struct f_trie *trie1 = f_new_trie(lp, 0); struct f_trie *trie2 = f_new_trie(lp, 0); @@ -630,6 +641,136 @@ t_trie_same(void) lp_flush(lp); } + bt_bird_cleanup(); + return 1; +} + +static inline void +log_networks(const net_addr *a, const net_addr *b) +{ + if (bt_verbose >= BT_VERBOSE_ABSOLUTELY_ALL) + { + char buf0[64]; + char buf1[64]; + bt_format_net(buf0, 64, a); + bt_format_net(buf1, 64, b); + bt_debug("Found %s expected %s\n", buf0, buf1); + } +} + +static int +t_trie_walk(void) +{ + bt_bird_init(); + bt_config_parse(BT_CONFIG_SIMPLE); + + linpool *lp = lp_new_default(&root_pool); + for (int round = 0; round < TESTS_NUM*8; round++) + { + int level = round / TESTS_NUM; + int v6 = level % 2; + int num = PREFIXES_NUM * (int[]){1, 10, 100, 1000}[level / 2]; + int pos = 0, end = 0; + list *prefixes = make_random_prefix_list(lp, num, v6, 1); + struct f_trie *trie = make_trie_from_prefix_list(lp, prefixes); + struct f_prefix *pxset = malloc((num + 1) * sizeof(struct f_prefix)); + + struct f_prefix_node *n; + WALK_LIST(n, *prefixes) + pxset[pos++] = n->prefix; + memset(&pxset[pos], 0, sizeof (struct f_prefix)); + + qsort(pxset, num, sizeof(struct f_prefix), compare_prefixes); + + + /* Full walk */ + bt_debug("Full walk (round %d, %d nets)\n", round, num); + + pos = 0; + TRIE_WALK(trie, net, NULL) + { + log_networks(&net, &pxset[pos].net); + bt_assert(net_equal(&net, &pxset[pos].net)); + + /* Skip possible duplicates */ + while (net_equal(&pxset[pos].net, &pxset[pos + 1].net)) + pos++; + + pos++; + } + TRIE_WALK_END; + + bt_assert(pos == num); + bt_debug("Full walk done\n"); + + + /* Prepare net for subnet walk - start with random prefix */ + pos = bt_random() % num; + end = pos + (int[]){2, 2, 3, 4}[level / 2]; + end = MIN(end, num); + + struct f_prefix from = pxset[pos]; + + /* Find a common superprefix to several subsequent prefixes */ + for (; pos < end; pos++) + { + if (net_equal(&from.net, &pxset[pos].net)) + continue; + + int common = !v6 ? + ip4_pxlen(net4_prefix(&from.net), net4_prefix(&pxset[pos].net)) : + ip6_pxlen(net6_prefix(&from.net), net6_prefix(&pxset[pos].net)); + from.net.pxlen = MIN(from.net.pxlen, common); + + if (!v6) + ((net_addr_ip4 *) &from.net)->prefix = + ip4_and(net4_prefix(&from.net), net4_prefix(&pxset[pos].net)); + else + ((net_addr_ip6 *) &from.net)->prefix = + ip6_and(net6_prefix(&from.net), net6_prefix(&pxset[pos].net)); + } + + /* Fix irrelevant bits */ + if (!v6) + ((net_addr_ip4 *) &from.net)->prefix = + ip4_and(net4_prefix(&from.net), ip4_mkmask(net4_pxlen(&from.net))); + else + ((net_addr_ip6 *) &from.net)->prefix = + ip6_and(net6_prefix(&from.net), ip6_mkmask(net6_pxlen(&from.net))); + + + /* Find initial position for final prefix */ + for (pos = 0; pos < num; pos++) + if (compare_prefixes(&pxset[pos], &from) >= 0) + break; + + int p0 = pos; + char buf0[64]; + bt_format_net(buf0, 64, &from.net); + bt_debug("Subnet walk for %s (round %d, %d nets)\n", buf0, round, num); + + /* Subnet walk */ + TRIE_WALK(trie, net, &from.net) + { + log_networks(&net, &pxset[pos].net); + bt_assert(net_equal(&net, &pxset[pos].net)); + bt_assert(net_in_netX(&net, &from.net)); + + /* Skip possible duplicates */ + while (net_equal(&pxset[pos].net, &pxset[pos + 1].net)) + pos++; + + pos++; + } + TRIE_WALK_END; + + bt_assert((pos == num) || !net_in_netX(&pxset[pos].net, &from.net)); + bt_debug("Subnet walk done for %s (found %d nets)\n", buf0, pos - p0); + + lp_flush(lp); + } + + bt_bird_cleanup(); return 1; } @@ -642,6 +783,7 @@ main(int argc, char *argv[]) bt_test_suite(t_match_inner_net, "Testing random inner prefix matching"); bt_test_suite(t_match_outer_net, "Testing random outer prefix matching"); bt_test_suite(t_trie_same, "A trie filled forward should be same with a trie filled backward."); + bt_test_suite(t_trie_walk, "Testing TRIE_WALK() on random tries"); // bt_test_suite(t_bench_trie_datasets_subset, "Benchmark tries from datasets by random subset of nets"); // bt_test_suite(t_bench_trie_datasets_random, "Benchmark tries from datasets by generated addresses"); |