diff options
Diffstat (limited to '')
| -rw-r--r-- | modules/hints/hints.c | 677 |
1 files changed, 677 insertions, 0 deletions
diff --git a/modules/hints/hints.c b/modules/hints/hints.c new file mode 100644 index 0000000..34c08b9 --- /dev/null +++ b/modules/hints/hints.c @@ -0,0 +1,677 @@ +/* Copyright (C) CZ.NIC, z.s.p.o. <knot-resolver@labs.nic.cz> + * SPDX-License-Identifier: GPL-3.0-or-later + */ + +/** + * @file hints.c + * @brief Constructed zone cut from the hosts-like file, see @zonecut.h + * + * The module provides an override for queried address records. + */ + +#include <libknot/packet/pkt.h> +#include <libknot/descriptor.h> +#include <ccan/json/json.h> +#include <ucw/mempool.h> +#include <contrib/cleanup.h> +#include <lauxlib.h> + +#include "daemon/engine.h" +#include "lib/zonecut.h" +#include "lib/module.h" +#include "lib/layer.h" + +#include <inttypes.h> +#include <math.h> + +/* Defaults */ +#define VERBOSE_MSG(qry, ...) kr_log_q(qry, HINT, __VA_ARGS__) +#define ERR_MSG(...) kr_log_error(HINT, "[ ]" __VA_ARGS__) + +struct hints_data { + struct kr_zonecut hints; + struct kr_zonecut reverse_hints; + bool use_nodata; /**< See hint_use_nodata() description, exposed via lua. */ + uint32_t ttl; /**< TTL used for the hints, exposed via lua. */ +}; +static const uint32_t HINTS_TTL_DEFAULT = 5; + +/** Useful for returning from module properties. */ +static char * bool2jsonstr(bool val) +{ + char *result = NULL; + if (-1 == asprintf(&result, "{ \"result\": %s }", val ? "true" : "false")) + result = NULL; + return result; +} + +static int put_answer(knot_pkt_t *pkt, struct kr_query *qry, knot_rrset_t *rr, bool use_nodata) +{ + int ret = 0; + if (!knot_rrset_empty(rr) || use_nodata) { + /* Update packet question */ + if (!knot_dname_is_equal(knot_pkt_qname(pkt), rr->owner)) { + kr_pkt_recycle(pkt); + knot_pkt_put_question(pkt, qry->sname, qry->sclass, qry->stype); + } + if (!knot_rrset_empty(rr)) { + /* Append to packet */ + ret = knot_pkt_put_rotate(pkt, KNOT_COMPR_HINT_QNAME, rr, + qry->reorder, KNOT_PF_FREE); + } else { + /* Return empty answer if name exists, but type doesn't match */ + knot_wire_set_aa(pkt->wire); + } + } else { + ret = kr_error(ENOENT); + } + /* Clear RR if failed */ + if (ret != 0) { + knot_rrset_clear(rr, &pkt->mm); + } + return ret; +} + +static int satisfy_reverse(/*const*/ struct hints_data *data, + knot_pkt_t *pkt, struct kr_query *qry) +{ + /* Find a matching name */ + pack_t *addr_set = kr_zonecut_find(&data->reverse_hints, qry->sname); + if (!addr_set || addr_set->len == 0) { + return kr_error(ENOENT); + } + knot_dname_t *qname = knot_dname_copy(qry->sname, &pkt->mm); + knot_rrset_t rr; + knot_rrset_init(&rr, qname, KNOT_RRTYPE_PTR, KNOT_CLASS_IN, data->ttl); + + /* Append address records from hints */ + uint8_t *addr = pack_last(*addr_set); + if (addr != NULL) { + size_t len = pack_obj_len(addr); + void *addr_val = pack_obj_val(addr); + knot_rrset_add_rdata(&rr, addr_val, len, &pkt->mm); + } + + return put_answer(pkt, qry, &rr, data->use_nodata); +} + +static int satisfy_forward(/*const*/ struct hints_data *data, + knot_pkt_t *pkt, struct kr_query *qry) +{ + /* Find a matching name */ + pack_t *addr_set = kr_zonecut_find(&data->hints, qry->sname); + if (!addr_set || addr_set->len == 0) { + return kr_error(ENOENT); + } + knot_dname_t *qname = knot_dname_copy(qry->sname, &pkt->mm); + knot_rrset_t rr; + knot_rrset_init(&rr, qname, qry->stype, qry->sclass, data->ttl); + + size_t family_len; + switch (rr.type) { + case KNOT_RRTYPE_A: + family_len = sizeof(struct in_addr); + break; + case KNOT_RRTYPE_AAAA: + family_len = sizeof(struct in6_addr); + break; + default: + goto finish; + }; + + /* Append address records from hints */ + uint8_t *addr = pack_head(*addr_set); + while (addr != pack_tail(*addr_set)) { + size_t len = pack_obj_len(addr); + void *addr_val = pack_obj_val(addr); + if (len == family_len) { + knot_rrset_add_rdata(&rr, addr_val, len, &pkt->mm); + } + addr = pack_obj_next(addr); + } +finish: + return put_answer(pkt, qry, &rr, data->use_nodata); +} + +static int query(kr_layer_t *ctx, knot_pkt_t *pkt) +{ + struct kr_query *qry = ctx->req->current_query; + if (!qry || (ctx->state & KR_STATE_FAIL)) { + return ctx->state; + } + + struct kr_module *module = ctx->api->data; + struct hints_data *data = module->data; + if (!data) { /* No valid file. */ + return ctx->state; + } + /* We can optimize for early return like this: */ + if (!data->use_nodata && qry->stype != KNOT_RRTYPE_A + && qry->stype != KNOT_RRTYPE_AAAA && qry->stype != KNOT_RRTYPE_PTR) { + return ctx->state; + } + /* FIXME: putting directly into packet breaks ordering in case the hint + * is applied after a CNAME jump. */ + if (knot_dname_in_bailiwick(qry->sname, (const uint8_t *)"\4arpa\0") >= 0) { + if (satisfy_reverse(data, pkt, qry) != 0) + return ctx->state; + } else { + if (satisfy_forward(data, pkt, qry) != 0) + return ctx->state; + } + + VERBOSE_MSG(qry, "<= answered from hints\n"); + qry->flags.DNSSEC_WANT = false; /* Never authenticated */ + qry->flags.CACHED = true; + qry->flags.NO_MINIMIZE = true; + pkt->parsed = pkt->size; + knot_wire_set_qr(pkt->wire); + return KR_STATE_DONE; +} + +static int parse_addr_str(union kr_sockaddr *sa, const char *addr) +{ + int family = strchr(addr, ':') ? AF_INET6 : AF_INET; + memset(sa, 0, sizeof(*sa)); + sa->ip.sa_family = family; + char *addr_bytes = (/*const*/char *)kr_inaddr(&sa->ip); + if (inet_pton(family, addr, addr_bytes) != 1) { + return kr_error(EILSEQ); + } + return 0; +} + +/** @warning _NOT_ thread-safe; returns a pointer to static data! */ +static const knot_dname_t * raw_addr2reverse(const uint8_t *raw_addr, int family) +{ + #define REV_MAXLEN (4*16 + 16 /* the suffix, terminator, etc. */) + char reverse_addr[REV_MAXLEN]; + static knot_dname_t dname[REV_MAXLEN]; + #undef REV_MAXLEN + + if (family == AF_INET) { + snprintf(reverse_addr, sizeof(reverse_addr), + "%d.%d.%d.%d.in-addr.arpa.", + raw_addr[3], raw_addr[2], raw_addr[1], raw_addr[0]); + } else if (family == AF_INET6) { + char *ra_it = reverse_addr; + for (int i = 15; i >= 0; --i) { + ssize_t free_space = reverse_addr + sizeof(reverse_addr) - ra_it; + int written = snprintf(ra_it, free_space, "%x.%x.", + raw_addr[i] & 0x0f, raw_addr[i] >> 4); + if (kr_fails_assert(written < free_space)) + return NULL; + ra_it += written; + } + ssize_t free_space = reverse_addr + sizeof(reverse_addr) - ra_it; + if (snprintf(ra_it, free_space, "ip6.arpa.") >= free_space) { + return NULL; + } + } else { + return NULL; + } + + if (!knot_dname_from_str(dname, reverse_addr, sizeof(dname))) { + return NULL; + } + return dname; +} + +static const knot_dname_t * addr2reverse(const char *addr) +{ + /* Parse address string */ + union kr_sockaddr ia; + if (parse_addr_str(&ia, addr) != 0) { + return NULL; + } + return raw_addr2reverse((const /*sign*/uint8_t *)kr_inaddr(&ia.ip), + kr_inaddr_family(&ia.ip)); +} + +static int add_pair(struct kr_zonecut *hints, const char *name, const char *addr) +{ + /* Build key */ + knot_dname_t key[KNOT_DNAME_MAXLEN]; + if (!knot_dname_from_str(key, name, sizeof(key))) { + return kr_error(EINVAL); + } + knot_dname_to_lower(key); + + union kr_sockaddr ia; + if (parse_addr_str(&ia, addr) != 0) { + return kr_error(EINVAL); + } + + return kr_zonecut_add(hints, key, kr_inaddr(&ia.ip), kr_inaddr_len(&ia.ip)); +} + +static int add_reverse_pair(struct kr_zonecut *hints, const char *name, const char *addr) +{ + const knot_dname_t *key = addr2reverse(addr); + + if (key == NULL) { + return kr_error(EINVAL); + } + + knot_dname_t ptr_name[KNOT_DNAME_MAXLEN]; + if (!knot_dname_from_str(ptr_name, name, sizeof(ptr_name))) { + return kr_error(EINVAL); + } + + return kr_zonecut_add(hints, key, ptr_name, knot_dname_size(ptr_name)); +} + +/** For a given name, remove either one address or all of them (if == NULL). + * + * Also remove the corresponding reverse records. + */ +static int del_pair(struct hints_data *data, const char *name, const char *addr) +{ + /* Build key */ + knot_dname_t key[KNOT_DNAME_MAXLEN]; + if (!knot_dname_from_str(key, name, sizeof(key))) { + return kr_error(EINVAL); + } + int key_len = knot_dname_size(key); + + if (addr) { + /* Remove the pair. */ + union kr_sockaddr ia; + if (parse_addr_str(&ia, addr) != 0) { + return kr_error(EINVAL); + } + + const knot_dname_t *reverse_key = addr2reverse(addr); + kr_zonecut_del(&data->reverse_hints, reverse_key, key, key_len); + return kr_zonecut_del(&data->hints, key, + kr_inaddr(&ia.ip), kr_inaddr_len(&ia.ip)); + } + /* We're removing everything for the name; + * first find the name's pack */ + pack_t *addr_set = kr_zonecut_find(&data->hints, key); + if (!addr_set || addr_set->len == 0) { + return kr_error(ENOENT); + } + + /* Remove address records in hints from reverse_hints. */ + + for (uint8_t *a = pack_head(*addr_set); a != pack_tail(*addr_set); + a = pack_obj_next(a)) { + void *addr_val = pack_obj_val(a); + int family = pack_obj_len(a) == kr_family_len(AF_INET) + ? AF_INET : AF_INET6; + const knot_dname_t *reverse_key = raw_addr2reverse(addr_val, family); + if (reverse_key != NULL) { + kr_zonecut_del(&data->reverse_hints, reverse_key, key, key_len); + } + } + + /* Remove the whole name. */ + return kr_zonecut_del_all(&data->hints, key); +} + +static int load_file(struct kr_module *module, const char *path) +{ + auto_fclose FILE *fp = fopen(path, "r"); + if (fp == NULL) { + ERR_MSG("reading '%s' failed: %s\n", path, strerror(errno)); + return kr_error(errno); + } else { + VERBOSE_MSG(NULL, "reading '%s'\n", path); + } + + /* Load file to map */ + struct hints_data *data = module->data; + size_t line_len_unused = 0; + size_t count = 0; + size_t line_count = 0; + auto_free char *line = NULL; + int ret = kr_ok(); + + while (getline(&line, &line_len_unused, fp) > 0) { + ++line_count; + /* Ingore #comments as described in man hosts.5 */ + char *comm = strchr(line, '#'); + if (comm) { + *comm = '\0'; + } + + char *saveptr = NULL; + const char *addr = strtok_r(line, " \t\n", &saveptr); + if (addr == NULL || strlen(addr) == 0) { + continue; + } + const char *canonical_name = strtok_r(NULL, " \t\n", &saveptr); + if (canonical_name == NULL) { + ret = -1; + goto error; + } + /* Since the last added PTR records takes preference, + * we add canonical name as the last one. */ + const char *name_tok; + while ((name_tok = strtok_r(NULL, " \t\n", &saveptr)) != NULL) { + ret = add_pair(&data->hints, name_tok, addr); + if (!ret) { + ret = add_reverse_pair(&data->reverse_hints, name_tok, addr); + } + if (ret) { + ret = -1; + goto error; + } + count += 1; + } + ret = add_pair(&data->hints, canonical_name, addr); + if (!ret) { + ret = add_reverse_pair(&data->reverse_hints, canonical_name, addr); + } + if (ret) { + ret = -1; + goto error; + } + count += 1; + } +error: + if (ret) { + ret = kr_error(ret); + ERR_MSG("%s:%zu: invalid syntax\n", path, line_count); + } + VERBOSE_MSG(NULL, "loaded %zu hints\n", count); + return ret; +} + +static char* hint_add_hosts(void *env, struct kr_module *module, const char *args) +{ + if (!args) + args = "/etc/hosts"; + int err = load_file(module, args); + return bool2jsonstr(err == kr_ok()); +} + +/** + * Set name => address hint. + * + * Input: { name, address } + * Output: { result: bool } + * + */ +static char* hint_set(void *env, struct kr_module *module, const char *args) +{ + struct hints_data *data = module->data; + if (!args) + return NULL; + auto_free char *args_copy = strdup(args); + if (!args_copy) + return NULL; + + int ret = -1; + char *addr = strchr(args_copy, ' '); + if (addr) { + *addr = '\0'; + ++addr; + ret = add_reverse_pair(&data->reverse_hints, args_copy, addr); + if (ret) { + del_pair(data, args_copy, addr); + } else { + ret = add_pair(&data->hints, args_copy, addr); + } + } + + return bool2jsonstr(ret == 0); +} + +static char* hint_del(void *env, struct kr_module *module, const char *args) +{ + struct hints_data *data = module->data; + if (!args) + return NULL; + auto_free char *args_copy = strdup(args); + if (!args_copy) + return NULL; + + int ret = -1; + char *addr = strchr(args_copy, ' '); + if (addr) { + *addr = '\0'; + ++addr; + } + ret = del_pair(data, args_copy, addr); + + return bool2jsonstr(ret == 0); +} + +/** @internal Pack address list into JSON array. */ +static JsonNode *pack_addrs(pack_t *pack) +{ + char buf[INET6_ADDRSTRLEN]; + JsonNode *root = json_mkarray(); + uint8_t *addr = pack_head(*pack); + while (addr != pack_tail(*pack)) { + size_t len = pack_obj_len(addr); + int family = len == sizeof(struct in_addr) ? AF_INET : AF_INET6; + if (!inet_ntop(family, pack_obj_val(addr), buf, sizeof(buf))) { + break; + } + json_append_element(root, json_mkstring(buf)); + addr = pack_obj_next(addr); + } + return root; +} + +static char* pack_hints(struct kr_zonecut *hints); +/** + * Retrieve address hints, either for given name or for all names. + * + * Input: name + * Output: NULL or "{ address1, address2, ... }" + */ +static char* hint_get(void *env, struct kr_module *module, const char *args) +{ + struct kr_zonecut *hints = &((struct hints_data *) module->data)->hints; + if (kr_fails_assert(hints)) + return NULL; + + if (!args) { + return pack_hints(hints); + } + + knot_dname_t key[KNOT_DNAME_MAXLEN]; + pack_t *pack = NULL; + if (knot_dname_from_str(key, args, sizeof(key))) { + pack = kr_zonecut_find(hints, key); + } + if (!pack || pack->len == 0) { + return NULL; + } + + char *result = NULL; + JsonNode *root = pack_addrs(pack); + if (root) { + result = json_encode(root); + json_delete(root); + } + return result; +} + +/** @internal Pack all hints into serialized JSON. */ +static char* pack_hints(struct kr_zonecut *hints) { + char *result = NULL; + JsonNode *root_node = json_mkobject(); + trie_it_t *it; + for (it = trie_it_begin(hints->nsset); !trie_it_finished(it); trie_it_next(it)) { + KR_DNAME_GET_STR(nsname_str, (const knot_dname_t *)trie_it_key(it, NULL)); + JsonNode *addr_list = pack_addrs((pack_t *)*trie_it_val(it)); + if (!addr_list) goto error; + json_append_member(root_node, nsname_str, addr_list); + } + result = json_encode(root_node); +error: + trie_it_free(it); + json_delete(root_node); + return result; +} + +static void unpack_hint(struct kr_zonecut *root_hints, JsonNode *table, const char *name) +{ + JsonNode *node = NULL; + json_foreach(node, table) { + switch(node->tag) { + case JSON_STRING: add_pair(root_hints, name ? name : node->key, node->string_); break; + case JSON_ARRAY: unpack_hint(root_hints, node, name ? name : node->key); break; + default: continue; + } + } +} + +/** + * Get/set root hints set. + * + * Input: { name: [addr_list], ... } + * Output: current list + * + */ +static char* hint_root(void *env, struct kr_module *module, const char *args) +{ + struct engine *engine = env; + struct kr_context *ctx = &engine->resolver; + struct kr_zonecut *root_hints = &ctx->root_hints; + /* Replace root hints if parameter is set */ + if (args && args[0] != '\0') { + JsonNode *root_node = json_decode(args); + kr_zonecut_set(root_hints, (const uint8_t *)""); + unpack_hint(root_hints, root_node, NULL); + json_delete(root_node); + } + /* Return current root hints */ + return pack_hints(root_hints); +} + +static char* hint_root_file(void *env, struct kr_module *module, const char *args) +{ + struct engine *engine = env; + struct kr_context *ctx = &engine->resolver; + const char *err_msg = engine_hint_root_file(ctx, args); + if (err_msg) { + luaL_error(engine->L, "error when opening '%s': %s", args, err_msg); + } + return strdup(err_msg ? err_msg : ""); +} + +static char* hint_use_nodata(void *env, struct kr_module *module, const char *args) +{ + struct hints_data *data = module->data; + if (!args) { + return NULL; + } + + JsonNode *root_node = json_decode(args); + if (!root_node || root_node->tag != JSON_BOOL) { + json_delete(root_node); + return bool2jsonstr(false); + } + + data->use_nodata = root_node->bool_; + json_delete(root_node); + return bool2jsonstr(true); +} + +static char* hint_ttl(void *env, struct kr_module *module, const char *args) +{ + struct hints_data *data = module->data; + + /* Do no change on nonsense TTL values (incl. suspicious floats). */ + JsonNode *root_node = args ? json_decode(args) : NULL; + if (root_node && root_node->tag == JSON_NUMBER) { + double ttl_d = root_node->number_; + uint32_t ttl = (uint32_t)round(ttl_d); + if (ttl_d >= 0 && fabs(ttl_d - ttl) * 64 < 1) { + data->ttl = ttl; + } + } + json_delete(root_node); + + /* Always return the current TTL setting. Plain number is valid JSON. */ + char *result = NULL; + if (-1 == asprintf(&result, "%"PRIu32, data->ttl)) { + result = NULL; + } + return result; +} + +/** Basic initialization: get a memory pool, etc. */ +KR_EXPORT +int hints_init(struct kr_module *module) +{ + static kr_layer_api_t layer = { + .produce = &query, + }; + /* Store module reference */ + layer.data = module; + module->layer = &layer; + + static const struct kr_prop props[] = { + { &hint_set, "set", "Set {name, address} hint.", }, + { &hint_del, "del", "Delete one {name, address} hint or all addresses for the name.", }, + { &hint_get, "get", "Retrieve hint for given name.", }, + { &hint_ttl, "ttl", "Set/get TTL used for the hints.", }, + { &hint_add_hosts, "add_hosts", "Load a file with hosts-like formatting and add contents into hints.", }, + { &hint_root, "root", "Replace root hints set (empty value to return current list).", }, + { &hint_root_file, "root_file", "Replace root hints set from a zonefile.", }, + { &hint_use_nodata, "use_nodata", "Synthesise NODATA if name matches, but type doesn't. True by default.", }, + { NULL, NULL, NULL } + }; + module->props = props; + + knot_mm_t *pool = mm_ctx_mempool2(MM_DEFAULT_BLKSIZE); + if (!pool) { + return kr_error(ENOMEM); + } + struct hints_data *data = mm_alloc(pool, sizeof(struct hints_data)); + if (!data) { + mp_delete(pool->ctx); + return kr_error(ENOMEM); + } + kr_zonecut_init(&data->hints, (const uint8_t *)(""), pool); + kr_zonecut_init(&data->reverse_hints, (const uint8_t *)(""), pool); + data->use_nodata = true; + data->ttl = HINTS_TTL_DEFAULT; + module->data = data; + + return kr_ok(); +} + +/** Release all resources. */ +KR_EXPORT +int hints_deinit(struct kr_module *module) +{ + struct hints_data *data = module->data; + if (data) { + kr_zonecut_deinit(&data->hints); + kr_zonecut_deinit(&data->reverse_hints); + mp_delete(data->hints.pool->ctx); + module->data = NULL; + } + return kr_ok(); +} + +/** Drop all hints, and load a hosts file if any was specified. + * + * It seems slightly strange to drop all, but keep doing that for now. + */ +KR_EXPORT +int hints_config(struct kr_module *module, const char *conf) +{ + hints_deinit(module); + int err = hints_init(module); + if (err != kr_ok()) { + return err; + } + + if (conf && conf[0]) { + return load_file(module, conf); + } + return kr_ok(); +} + +KR_MODULE_EXPORT(hints) + +#undef VERBOSE_MSG |