diff options
Diffstat (limited to 'lib/resolve.c')
| -rw-r--r-- | lib/resolve.c | 1695 |
1 files changed, 1695 insertions, 0 deletions
diff --git a/lib/resolve.c b/lib/resolve.c new file mode 100644 index 0000000..aa3d521 --- /dev/null +++ b/lib/resolve.c @@ -0,0 +1,1695 @@ +/* Copyright (C) CZ.NIC, z.s.p.o. <knot-resolver@labs.nic.cz> + * SPDX-License-Identifier: GPL-3.0-or-later + */ + +#include <ctype.h> +#include <inttypes.h> +#include <stdio.h> +#include <fcntl.h> +#include <arpa/inet.h> +#include <libknot/rrtype/rdname.h> +#include <libknot/descriptor.h> +#include <ucw/mempool.h> +#include <sys/socket.h> +#include "lib/resolve.h" +#include "lib/layer.h" +#include "lib/rplan.h" +#include "lib/layer/iterate.h" +#include "lib/dnssec/ta.h" +#include "lib/dnssec.h" +#if ENABLE_COOKIES +#include "lib/cookies/control.h" +#include "lib/cookies/helper.h" +#include "lib/cookies/nonce.h" +#else /* Define compatibility macros */ +#define KNOT_EDNS_OPTION_COOKIE 10 +#endif /* ENABLE_COOKIES */ + +#define VERBOSE_MSG(qry, ...) kr_log_q((qry), RESOLVER, __VA_ARGS__) + +bool kr_rank_check(uint8_t rank) +{ + switch (rank & ~KR_RANK_AUTH) { + case KR_RANK_INITIAL: + case KR_RANK_OMIT: + case KR_RANK_TRY: + case KR_RANK_INDET: + case KR_RANK_BOGUS: + case KR_RANK_MISMATCH: + case KR_RANK_MISSING: + case KR_RANK_INSECURE: + case KR_RANK_SECURE: + return true; + default: + return false; + } +} + +bool kr_rank_test(uint8_t rank, uint8_t kr_flag) +{ + if (kr_fails_assert(kr_rank_check(rank) && kr_rank_check(kr_flag))) + return false; + if (kr_flag == KR_RANK_AUTH) { + return rank & KR_RANK_AUTH; + } + if (kr_fails_assert(!(kr_flag & KR_RANK_AUTH))) + return false; + /* The rest are exclusive values - exactly one has to be set. */ + return (rank & ~KR_RANK_AUTH) == kr_flag; +} + +/** @internal Set @a yielded to all RRs with matching @a qry_uid. */ +static void set_yield(ranked_rr_array_t *array, const uint32_t qry_uid, const bool yielded) +{ + for (unsigned i = 0; i < array->len; ++i) { + ranked_rr_array_entry_t *entry = array->at[i]; + if (entry->qry_uid == qry_uid) { + entry->yielded = yielded; + } + } +} + +/** + * @internal Defer execution of current query. + * The current layer state and input will be pushed to a stack and resumed on next iteration. + */ +static int consume_yield(kr_layer_t *ctx, knot_pkt_t *pkt) +{ + struct kr_request *req = ctx->req; + size_t pkt_size = pkt->size; + if (knot_pkt_has_tsig(pkt)) { + pkt_size += pkt->tsig_wire.len; + } + knot_pkt_t *pkt_copy = knot_pkt_new(NULL, pkt_size, &req->pool); + struct kr_layer_pickle *pickle = mm_alloc(&req->pool, sizeof(*pickle)); + if (pickle && pkt_copy && knot_pkt_copy(pkt_copy, pkt) == 0) { + struct kr_query *qry = req->current_query; + pickle->api = ctx->api; + pickle->state = ctx->state; + pickle->pkt = pkt_copy; + pickle->next = qry->deferred; + qry->deferred = pickle; + set_yield(&req->answ_selected, qry->uid, true); + set_yield(&req->auth_selected, qry->uid, true); + return kr_ok(); + } + return kr_error(ENOMEM); +} +static int begin_yield(kr_layer_t *ctx) { return kr_ok(); } +static int reset_yield(kr_layer_t *ctx) { return kr_ok(); } +static int finish_yield(kr_layer_t *ctx) { return kr_ok(); } +static int produce_yield(kr_layer_t *ctx, knot_pkt_t *pkt) { return kr_ok(); } +static int checkout_yield(kr_layer_t *ctx, knot_pkt_t *packet, struct sockaddr *dst, int type) { return kr_ok(); } +static int answer_finalize_yield(kr_layer_t *ctx) { return kr_ok(); } + +/** @internal Macro for iterating module layers. */ +#define RESUME_LAYERS(from, r, qry, func, ...) \ + (r)->current_query = (qry); \ + for (size_t i = (from); i < (r)->ctx->modules->len; ++i) { \ + struct kr_module *mod = (r)->ctx->modules->at[i]; \ + if (mod->layer) { \ + struct kr_layer layer = {.state = (r)->state, .api = mod->layer, .req = (r)}; \ + if (layer.api && layer.api->func) { \ + (r)->state = layer.api->func(&layer, ##__VA_ARGS__); \ + /* It's an easy mistake to return error code, for example. */ \ + /* (though we could allow such an overload later) */ \ + if (kr_fails_assert(kr_state_consistent((r)->state))) { \ + (r)->state = KR_STATE_FAIL; \ + } else \ + if ((r)->state == KR_STATE_YIELD) { \ + func ## _yield(&layer, ##__VA_ARGS__); \ + break; \ + } \ + } \ + } \ + } /* Invalidate current query. */ \ + (r)->current_query = NULL + +/** @internal Macro for starting module iteration. */ +#define ITERATE_LAYERS(req, qry, func, ...) RESUME_LAYERS(0, req, qry, func, ##__VA_ARGS__) + +/** @internal Find layer id matching API. */ +static inline size_t layer_id(struct kr_request *req, const struct kr_layer_api *api) { + module_array_t *modules = req->ctx->modules; + for (size_t i = 0; i < modules->len; ++i) { + if (modules->at[i]->layer == api) { + return i; + } + } + return 0; /* Not found, try all. */ +} + +/* @internal We don't need to deal with locale here */ +KR_CONST static inline bool isletter(unsigned chr) +{ return (chr | 0x20 /* tolower */) - 'a' <= 'z' - 'a'; } + +/* Randomize QNAME letter case. + * This adds 32 bits of randomness at maximum, but that's more than an average domain name length. + * https://tools.ietf.org/html/draft-vixie-dnsext-dns0x20-00 + */ +static void randomized_qname_case(knot_dname_t * restrict qname, uint32_t secret) +{ + if (secret == 0) + return; + if (kr_fails_assert(qname)) + return; + const int len = knot_dname_size(qname) - 2; /* Skip first, last label. First is length, last is always root */ + for (int i = 0; i < len; ++i) { + /* Note: this relies on the fact that correct label lengths + * can't pass the isletter() test (by "luck"). */ + if (isletter(*++qname)) { + *qname ^= ((secret >> (i & 31)) & 1) * 0x20; + } + } +} + +/** This turns of QNAME minimisation if there is a non-terminal between current zone cut, and name target. + * It save several minimization steps, as the zone cut is likely final one. + */ +static void check_empty_nonterms(struct kr_query *qry, knot_pkt_t *pkt, struct kr_cache *cache, uint32_t timestamp) +{ + // FIXME cleanup, etc. +#if 0 + if (qry->flags.NO_MINIMIZE) { + return; + } + + const knot_dname_t *target = qry->sname; + const knot_dname_t *cut_name = qry->zone_cut.name; + if (!target || !cut_name) + return; + + struct kr_cache_entry *entry = NULL; + /* @note: The non-terminal must be direct child of zone cut (e.g. label distance <= 2), + * otherwise this would risk leaking information to parent if the NODATA TTD > zone cut TTD. */ + int labels = knot_dname_labels(target, NULL) - knot_dname_labels(cut_name, NULL); + while (target[0] && labels > 2) { + target = knot_wire_next_label(target, NULL); + --labels; + } + for (int i = 0; i < labels; ++i) { + int ret = kr_cache_peek(cache, KR_CACHE_PKT, target, KNOT_RRTYPE_NS, &entry, ×tamp); + if (ret == 0) { /* Either NXDOMAIN or NODATA, start here. */ + /* @todo We could stop resolution here for NXDOMAIN, but we can't because of broken CDNs */ + qry->flags.NO_MINIMIZE = true; + kr_make_query(qry, pkt); + break; + } + kr_assert(target[0]); + target = knot_wire_next_label(target, NULL); + } + kr_cache_commit(cache); +#endif +} + +static int ns_fetch_cut(struct kr_query *qry, const knot_dname_t *requested_name, + struct kr_request *req, knot_pkt_t *pkt) +{ + /* It can occur that here parent query already have + * provably insecure zonecut which not in the cache yet. */ + struct kr_qflags pflags; + if (qry->parent) { + pflags = qry->parent->flags; + } + const bool is_insecure = qry->parent != NULL + && !(pflags.AWAIT_IPV4 || pflags.AWAIT_IPV6) + && (pflags.DNSSEC_INSECURE || pflags.DNSSEC_NODS); + + /* Want DNSSEC if it's possible to secure this name + * (e.g. is covered by any TA) */ + if (is_insecure) { + /* If parent is insecure we don't want DNSSEC + * even if cut name is covered by TA. */ + qry->flags.DNSSEC_WANT = false; + qry->flags.DNSSEC_INSECURE = true; + VERBOSE_MSG(qry, "=> going insecure because parent query is insecure\n"); + } else if (kr_ta_closest(req->ctx, qry->zone_cut.name, KNOT_RRTYPE_NS)) { + qry->flags.DNSSEC_WANT = true; + } else { + qry->flags.DNSSEC_WANT = false; + VERBOSE_MSG(qry, "=> going insecure because there's no covering TA\n"); + } + + struct kr_zonecut cut_found; + kr_zonecut_init(&cut_found, requested_name, req->rplan.pool); + /* Cut that has been found can differs from cut that has been requested. + * So if not already insecure, + * try to fetch ta & keys even if initial cut name not covered by TA */ + bool secure = !is_insecure; + int ret = kr_zonecut_find_cached(req->ctx, &cut_found, requested_name, + qry, &secure); + if (ret == kr_error(ENOENT)) { + /* No cached cut found, start from SBELT + * and issue priming query. */ + kr_zonecut_deinit(&cut_found); + ret = kr_zonecut_set_sbelt(req->ctx, &qry->zone_cut); + if (ret != 0) { + return KR_STATE_FAIL; + } + VERBOSE_MSG(qry, "=> using root hints\n"); + qry->flags.AWAIT_CUT = false; + return KR_STATE_DONE; + } else if (ret != kr_ok()) { + kr_zonecut_deinit(&cut_found); + return KR_STATE_FAIL; + } + + /* Find out security status. + * Go insecure if the zone cut is provably insecure */ + if ((qry->flags.DNSSEC_WANT) && !secure) { + VERBOSE_MSG(qry, "=> NS is provably without DS, going insecure\n"); + qry->flags.DNSSEC_WANT = false; + qry->flags.DNSSEC_INSECURE = true; + } + /* Zonecut name can change, check it again + * to prevent unnecessary DS & DNSKEY queries */ + if (!(qry->flags.DNSSEC_INSECURE) && + kr_ta_closest(req->ctx, cut_found.name, KNOT_RRTYPE_NS)) { + qry->flags.DNSSEC_WANT = true; + } else { + qry->flags.DNSSEC_WANT = false; + } + /* Check if any DNSKEY found for cached cut */ + if (qry->flags.DNSSEC_WANT && cut_found.key == NULL && + kr_zonecut_is_empty(&cut_found)) { + /* Cut found and there are no proofs of zone insecurity. + * But no DNSKEY found and no glue fetched. + * We have got circular dependency - must fetch A\AAAA + * from authoritative, but we have no key to verify it. */ + kr_zonecut_deinit(&cut_found); + if (requested_name[0] != '\0' ) { + /* If not root - try next label */ + return KR_STATE_CONSUME; + } + /* No cached cut & keys found, start from SBELT */ + ret = kr_zonecut_set_sbelt(req->ctx, &qry->zone_cut); + if (ret != 0) { + return KR_STATE_FAIL; + } + VERBOSE_MSG(qry, "=> using root hints\n"); + qry->flags.AWAIT_CUT = false; + return KR_STATE_DONE; + } + /* Use the found zone cut. */ + kr_zonecut_move(&qry->zone_cut, &cut_found); + /* Check if there's a non-terminal between target and current cut. */ + struct kr_cache *cache = &req->ctx->cache; + check_empty_nonterms(qry, pkt, cache, qry->timestamp.tv_sec); + /* Cut found */ + return KR_STATE_PRODUCE; +} + +static int edns_put(knot_pkt_t *pkt, bool reclaim) +{ + if (!pkt->opt_rr) { + return kr_ok(); + } + if (reclaim) { + /* Reclaim reserved size. */ + int ret = knot_pkt_reclaim(pkt, knot_edns_wire_size(pkt->opt_rr)); + if (ret != 0) { + return ret; + } + } + /* Write to packet. */ + if (kr_fails_assert(pkt->current == KNOT_ADDITIONAL)) + return kr_error(EINVAL); + return knot_pkt_put(pkt, KNOT_COMPR_HINT_NONE, pkt->opt_rr, KNOT_PF_FREE); +} + +/** Removes last EDNS OPT RR written to the packet. */ +static int edns_erase_and_reserve(knot_pkt_t *pkt) +{ + /* Nothing to be done. */ + if (!pkt || !pkt->opt_rr) { + return 0; + } + + /* Fail if the data are located elsewhere than at the end of packet. */ + if (pkt->current != KNOT_ADDITIONAL || + pkt->opt_rr != &pkt->rr[pkt->rrset_count - 1]) { + return -1; + } + + size_t len = knot_rrset_size(pkt->opt_rr); + int16_t rr_removed = pkt->opt_rr->rrs.count; + /* Decrease rrset counters. */ + pkt->rrset_count -= 1; + pkt->sections[pkt->current].count -= 1; + pkt->size -= len; + knot_wire_add_arcount(pkt->wire, -rr_removed); /* ADDITIONAL */ + + pkt->opt_rr = NULL; + + /* Reserve the freed space. */ + return knot_pkt_reserve(pkt, len); +} + +static inline size_t edns_padding_option_size(int32_t tls_padding) +{ + if (tls_padding == -1) + /* FIXME: we do not know how to reserve space for the + * default padding policy, since we can't predict what + * it will select. So i'm just guessing :/ */ + return KNOT_EDNS_OPTION_HDRLEN + 512; + if (tls_padding >= 2) + return KNOT_EDNS_OPTION_HDRLEN + tls_padding; + + return 0; +} + +static int edns_create(knot_pkt_t *pkt, const struct kr_request *req) +{ + pkt->opt_rr = knot_rrset_copy(req->ctx->upstream_opt_rr, &pkt->mm); + size_t wire_size = knot_edns_wire_size(pkt->opt_rr); +#if ENABLE_COOKIES + if (req->ctx->cookie_ctx.clnt.enabled || + req->ctx->cookie_ctx.srvr.enabled) { + wire_size += KR_COOKIE_OPT_MAX_LEN; + } +#endif /* ENABLE_COOKIES */ + if (req->qsource.flags.tls || req->qsource.comm_flags.tls) { + wire_size += edns_padding_option_size(req->ctx->tls_padding); + } + return knot_pkt_reserve(pkt, wire_size); +} + +/** + * @param all_secure optionally &&-combine security of written RRs into its value. + * (i.e. if you pass a pointer to false, it will always remain) + * @param all_cname optionally output if all written RRs are CNAMEs and RRSIGs of CNAMEs + * @return error code, ignoring if forced to truncate the packet. + */ +static int write_extra_ranked_records(const ranked_rr_array_t *arr, uint16_t reorder, + knot_pkt_t *answer, bool *all_secure, bool *all_cname) +{ + const bool has_dnssec = knot_pkt_has_dnssec(answer); + bool all_sec = true; + bool all_cn = (all_cname != NULL); /* optim.: init as false if not needed */ + int err = kr_ok(); + + for (size_t i = 0; i < arr->len; ++i) { + ranked_rr_array_entry_t * entry = arr->at[i]; + kr_assert(!entry->in_progress); + if (!entry->to_wire) { + continue; + } + knot_rrset_t *rr = entry->rr; + if (!has_dnssec) { + if (rr->type != knot_pkt_qtype(answer) && knot_rrtype_is_dnssec(rr->type)) { + continue; + } + } + err = knot_pkt_put_rotate(answer, 0, rr, reorder, 0); + if (err != KNOT_EOK) { + if (err == KNOT_ESPACE) { + err = kr_ok(); + } + break; + } + + if (rr->type != KNOT_RRTYPE_RRSIG) { + all_sec = all_sec && kr_rank_test(entry->rank, KR_RANK_SECURE); + } + all_cn = all_cn && kr_rrset_type_maysig(entry->rr) == KNOT_RRTYPE_CNAME; + } + + if (all_secure) { + *all_secure = *all_secure && all_sec; + } + if (all_cname) { + *all_cname = all_cn; + } + return err; +} + +static int pkt_padding(knot_pkt_t *packet, int32_t padding) +{ + knot_rrset_t *opt_rr = packet->opt_rr; + int32_t pad_bytes = -1; + + if (padding == -1) { /* use the default padding policy from libknot */ + pad_bytes = knot_pkt_default_padding_size(packet, opt_rr); + } + if (padding >= 2) { + int32_t max_pad_bytes = knot_edns_get_payload(opt_rr) - (packet->size + knot_rrset_size(opt_rr)); + pad_bytes = MIN(knot_edns_alignment_size(packet->size, knot_rrset_size(opt_rr), padding), + max_pad_bytes); + } + + if (pad_bytes >= 0) { + uint8_t zeros[MAX(1, pad_bytes)]; + memset(zeros, 0, sizeof(zeros)); + int r = knot_edns_add_option(opt_rr, KNOT_EDNS_OPTION_PADDING, + pad_bytes, zeros, &packet->mm); + if (r != KNOT_EOK) { + knot_rrset_clear(opt_rr, &packet->mm); + return kr_error(r); + } + } + return kr_ok(); +} + +/** @internal Add an EDNS padding RR into the answer if requested and required. */ +static int answer_padding(struct kr_request *request) +{ + if (kr_fails_assert(request && request->answer && request->ctx)) + return kr_error(EINVAL); + if (!request->qsource.flags.tls && !request->qsource.comm_flags.tls) { + /* Not meaningful to pad without encryption. */ + return kr_ok(); + } + return pkt_padding(request->answer, request->ctx->tls_padding); +} + +/* Make a clean SERVFAIL answer. */ +static void answer_fail(struct kr_request *request) +{ + /* Note: OPT in SERVFAIL response is still useful for cookies/additional info. */ + if (kr_log_is_debug(RESOLVER, request)) /* logging optimization */ + kr_log_req(request, 0, 0, RESOLVER, + "request failed, answering with empty SERVFAIL\n"); + knot_pkt_t *answer = request->answer; + knot_rrset_t *opt_rr = answer->opt_rr; /* it gets NULLed below */ + int ret = kr_pkt_clear_payload(answer); + knot_wire_clear_ad(answer->wire); + knot_wire_clear_aa(answer->wire); + knot_wire_set_rcode(answer->wire, KNOT_RCODE_SERVFAIL); + if (ret == 0 && opt_rr) { + knot_pkt_begin(answer, KNOT_ADDITIONAL); + answer->opt_rr = opt_rr; + answer_padding(request); /* Ignore failed padding in SERVFAIL answer. */ + edns_put(answer, false); + } +} + +/* Append EDNS records into the answer. */ +static int answer_append_edns(struct kr_request *request) +{ + knot_pkt_t *answer = request->answer; + if (!answer->opt_rr) + return kr_ok(); + int ret = answer_padding(request); + if (!ret) ret = knot_pkt_begin(answer, KNOT_ADDITIONAL); + if (!ret) ret = knot_pkt_put(answer, KNOT_COMPR_HINT_NONE, + answer->opt_rr, KNOT_PF_FREE); + return ret; +} + +static void answer_finalize(struct kr_request *request) +{ + struct kr_rplan *rplan = &request->rplan; + knot_pkt_t *answer = request->answer; + const uint8_t *q_wire = request->qsource.packet->wire; + + if (answer->rrset_count != 0) { + /* Non-standard: we assume the answer had been constructed. + * Let's check we don't have a "collision". */ + const ranked_rr_array_t *selected[] = kr_request_selected(request); + for (int psec = KNOT_ANSWER; psec <= KNOT_ADDITIONAL; ++psec) { + const ranked_rr_array_t *arr = selected[psec]; + for (ssize_t i = 0; i < arr->len; ++i) { + if (kr_fails_assert(!arr->at[i]->to_wire)) { + answer_fail(request); + return; + } + } + } + /* We only add EDNS, and we even assume AD bit was correct. */ + if (answer_append_edns(request)) { + answer_fail(request); + return; + } + return; + } + + struct kr_query *const last = + rplan->resolved.len > 0 ? array_tail(rplan->resolved) : NULL; + /* TODO ^^^^ this is slightly fragile */ + + if (!last) { + /* Suspicious: no kr_query got resolved (not even from cache), + * so let's (defensively) SERVFAIL the request. + * ATM many checks below depend on `last` anyway, + * so this helps to avoid surprises. */ + answer_fail(request); + return; + } + /* TODO: clean this up in !660 or followup, and it isn't foolproof anyway. */ + if (last->flags.DNSSEC_BOGUS + || (rplan->pending.len > 0 && array_tail(rplan->pending)->flags.DNSSEC_BOGUS)) { + if (!knot_wire_get_cd(q_wire)) { + answer_fail(request); + return; + } + } + + /* AD flag. We can only change `secure` from true to false. + * Be conservative. Primary approach: check ranks of all RRs in wire. + * Only "negative answers" need special handling. */ + bool secure = request->state == KR_STATE_DONE /*< suspicious otherwise */ + && knot_pkt_qtype(answer) != KNOT_RRTYPE_RRSIG; + if (last->flags.STUB) { + secure = false; /* don't trust forwarding for now */ + } + if (last->flags.DNSSEC_OPTOUT) { + VERBOSE_MSG(last, "insecure because of opt-out\n"); + secure = false; /* the last answer is insecure due to opt-out */ + } + + /* Write all RRsets meant for the answer. */ + bool answ_all_cnames = false/*arbitrary*/; + if (knot_pkt_begin(answer, KNOT_ANSWER) + || write_extra_ranked_records(&request->answ_selected, last->reorder, + answer, &secure, &answ_all_cnames) + || knot_pkt_begin(answer, KNOT_AUTHORITY) + || write_extra_ranked_records(&request->auth_selected, last->reorder, + answer, &secure, NULL) + || knot_pkt_begin(answer, KNOT_ADDITIONAL) + || write_extra_ranked_records(&request->add_selected, last->reorder, + answer, NULL/*not relevant to AD*/, NULL) + || answer_append_edns(request) + ) + { + answer_fail(request); + return; + } + + /* AD: "negative answers" need more handling. */ + if (kr_response_classify(answer) != PKT_NOERROR + /* Additionally check for CNAME chains that "end in NODATA", + * as those would also be PKT_NOERROR. */ + || (answ_all_cnames && knot_pkt_qtype(answer) != KNOT_RRTYPE_CNAME)) { + + secure = secure && last->flags.DNSSEC_WANT + && !last->flags.DNSSEC_BOGUS && !last->flags.DNSSEC_INSECURE; + } + + if (secure) { + struct kr_query *cname_parent = last->cname_parent; + while (cname_parent != NULL) { + if (cname_parent->flags.DNSSEC_OPTOUT) { + secure = false; + break; + } + cname_parent = cname_parent->cname_parent; + } + } + + /* No detailed analysis ATM, just _SECURE or not. + * LATER: request->rank might better be computed in validator's finish phase. */ + VERBOSE_MSG(last, "AD: request%s classified as SECURE\n", secure ? "" : " NOT"); + request->rank = secure ? KR_RANK_SECURE : KR_RANK_INITIAL; + + /* Set AD if secure and AD bit "was requested". */ + if (secure && !knot_wire_get_cd(q_wire) + && (knot_pkt_has_dnssec(answer) || knot_wire_get_ad(q_wire))) { + knot_wire_set_ad(answer->wire); + } +} + +static int query_finalize(struct kr_request *request, struct kr_query *qry, knot_pkt_t *pkt) +{ + knot_pkt_begin(pkt, KNOT_ADDITIONAL); + if (qry->flags.NO_EDNS) + return kr_ok(); + /* Remove any EDNS records from any previous iteration. */ + int ret = edns_erase_and_reserve(pkt); + if (ret) return ret; + ret = edns_create(pkt, request); + if (ret) return ret; + if (qry->flags.STUB) { + /* Stub resolution */ + knot_wire_set_rd(pkt->wire); + if (knot_wire_get_cd(request->qsource.packet->wire)) { + knot_wire_set_cd(pkt->wire); + } + } else { + /* Full resolution (ask for +cd and +do) */ + knot_edns_set_do(pkt->opt_rr); + knot_wire_set_cd(pkt->wire); + if (qry->flags.FORWARD) { + knot_wire_set_rd(pkt->wire); + } + } + return kr_ok(); +} + +int kr_resolve_begin(struct kr_request *request, struct kr_context *ctx) +{ + /* Initialize request */ + request->ctx = ctx; + request->answer = NULL; + request->options = ctx->options; + request->state = KR_STATE_CONSUME; + request->current_query = NULL; + array_init(request->answ_selected); + array_init(request->auth_selected); + array_init(request->add_selected); + request->answ_validated = false; + request->auth_validated = false; + request->rank = KR_RANK_INITIAL; + request->trace_log = NULL; + request->trace_finish = NULL; + + /* Expect first query */ + kr_rplan_init(&request->rplan, request, &request->pool); + return KR_STATE_CONSUME; +} + +static int resolve_query(struct kr_request *request, const knot_pkt_t *packet) +{ + struct kr_rplan *rplan = &request->rplan; + const knot_dname_t *qname = knot_pkt_qname(packet); + uint16_t qclass = knot_pkt_qclass(packet); + uint16_t qtype = knot_pkt_qtype(packet); + struct kr_query *qry = NULL; + struct kr_context *ctx = request->ctx; + struct kr_cookie_ctx *cookie_ctx = ctx ? &ctx->cookie_ctx : NULL; + + if (qname != NULL) { + qry = kr_rplan_push(rplan, NULL, qname, qclass, qtype); + } else if (cookie_ctx && cookie_ctx->srvr.enabled && + knot_wire_get_qdcount(packet->wire) == 0 && + knot_pkt_has_edns(packet) && + knot_pkt_edns_option(packet, KNOT_EDNS_OPTION_COOKIE)) { + /* Plan empty query only for cookies. */ + qry = kr_rplan_push_empty(rplan, NULL); + } + if (!qry) { + return KR_STATE_FAIL; + } + + if (qname != NULL) { + /* Deferred zone cut lookup for this query. */ + qry->flags.AWAIT_CUT = true; + /* Want DNSSEC if it's possible to secure this name (e.g. is covered by any TA) */ + if ((knot_wire_get_ad(packet->wire) || knot_pkt_has_dnssec(packet)) && + kr_ta_closest(request->ctx, qry->sname, qtype)) { + qry->flags.DNSSEC_WANT = true; + } + } + + /* Expect answer, pop if satisfied immediately */ + ITERATE_LAYERS(request, qry, begin); + if ((request->state & KR_STATE_DONE) != 0) { + kr_rplan_pop(rplan, qry); + } else if (qname == NULL) { + /* it is an empty query which must be resolved by + `begin` layer of cookie module. + If query isn't resolved, fail. */ + request->state = KR_STATE_FAIL; + } + return request->state; +} + +knot_rrset_t* kr_request_ensure_edns(struct kr_request *request) +{ + kr_require(request && request->answer && request->qsource.packet && request->ctx); + knot_pkt_t* answer = request->answer; + bool want_edns = knot_pkt_has_edns(request->qsource.packet); + if (!want_edns) { + kr_assert(!answer->opt_rr); + return answer->opt_rr; + } else if (answer->opt_rr) { + return answer->opt_rr; + } + + kr_assert(request->ctx->downstream_opt_rr); + answer->opt_rr = knot_rrset_copy(request->ctx->downstream_opt_rr, &answer->mm); + if (!answer->opt_rr) + return NULL; + if (knot_pkt_has_dnssec(request->qsource.packet)) + knot_edns_set_do(answer->opt_rr); + return answer->opt_rr; +} + +knot_pkt_t *kr_request_ensure_answer(struct kr_request *request) +{ + if (request->options.NO_ANSWER) { + kr_assert(request->state & KR_STATE_FAIL); + return NULL; + } + if (request->answer) + return request->answer; + + const knot_pkt_t *qs_pkt = request->qsource.packet; + if (kr_fails_assert(qs_pkt)) + goto fail; + // Find answer_max: limit on DNS wire length. + uint16_t answer_max; + const struct kr_request_qsource_flags *qs_flags = &request->qsource.flags; + const struct kr_request_qsource_flags *qs_cflags = &request->qsource.comm_flags; + if (kr_fails_assert(!(qs_flags->tls || qs_cflags->tls || qs_cflags->http) || qs_flags->tcp)) + goto fail; + if (!request->qsource.addr || qs_flags->tcp || qs_cflags->tcp) { + // not on UDP + answer_max = KNOT_WIRE_MAX_PKTSIZE; + } else if (knot_pkt_has_edns(qs_pkt)) { + // UDP with EDNS + answer_max = MIN(knot_edns_get_payload(qs_pkt->opt_rr), + knot_edns_get_payload(request->ctx->downstream_opt_rr)); + answer_max = MAX(answer_max, KNOT_WIRE_MIN_PKTSIZE); + } else { + // UDP without EDNS + answer_max = KNOT_WIRE_MIN_PKTSIZE; + } + + // Allocate the packet. + uint8_t *wire = NULL; + if (request->alloc_wire_cb) { + wire = request->alloc_wire_cb(request, &answer_max); + if (!wire) + goto enomem; + } + knot_pkt_t *answer = request->answer = + knot_pkt_new(wire, answer_max, &request->pool); + if (!answer || knot_pkt_init_response(answer, qs_pkt) != 0) { + kr_assert(!answer); // otherwise we messed something up + goto enomem; + } + if (!wire) + wire = answer->wire; + + // Much was done by knot_pkt_init_response() + knot_wire_set_ra(wire); + knot_wire_set_rcode(wire, KNOT_RCODE_NOERROR); + if (knot_wire_get_cd(qs_pkt->wire)) { + knot_wire_set_cd(wire); + } + + // Prepare EDNS if required. + if (knot_pkt_has_edns(qs_pkt) && kr_fails_assert(kr_request_ensure_edns(request))) + goto enomem; // answer is on mempool, so "leak" is OK + + return request->answer; +enomem: +fail: + request->state = KR_STATE_FAIL; // TODO: really combine with another flag? + return request->answer = NULL; +} + +int kr_resolve_consume(struct kr_request *request, struct kr_transport **transport, knot_pkt_t *packet) +{ + struct kr_rplan *rplan = &request->rplan; + + /* Empty resolution plan, push packet as the new query */ + if (packet && kr_rplan_empty(rplan)) { + return resolve_query(request, packet); + } + + /* Different processing for network error */ + struct kr_query *qry = array_tail(rplan->pending); + /* Check overall resolution time */ + if (kr_now() - qry->creation_time_mono >= KR_RESOLVE_TIME_LIMIT) { + kr_query_inform_timeout(request, qry); + return KR_STATE_FAIL; + } + bool tried_tcp = (qry->flags.TCP); + if (!packet || packet->size == 0) + return KR_STATE_PRODUCE; + + /* Packet cleared, derandomize QNAME. */ + knot_dname_t *qname_raw = kr_pkt_qname_raw(packet); + if (qname_raw && qry->secret != 0) { + randomized_qname_case(qname_raw, qry->secret); + } + request->state = KR_STATE_CONSUME; + if (qry->flags.CACHED) { + ITERATE_LAYERS(request, qry, consume, packet); + } else { + /* Fill in source and latency information. */ + request->upstream.rtt = kr_now() - qry->timestamp_mono; + request->upstream.transport = transport ? *transport : NULL; + ITERATE_LAYERS(request, qry, consume, packet); + /* Clear temporary information */ + request->upstream.transport = NULL; + request->upstream.rtt = 0; + } + + if (transport && !qry->flags.CACHED) { + if (!(request->state & KR_STATE_FAIL)) { + /* Do not complete NS address resolution on soft-fail. */ + const int rcode = knot_wire_get_rcode(packet->wire); + if (rcode != KNOT_RCODE_SERVFAIL && rcode != KNOT_RCODE_REFUSED) { + qry->flags.AWAIT_IPV6 = false; + qry->flags.AWAIT_IPV4 = false; + } + } + } + + if (request->state & KR_STATE_FAIL) { + qry->flags.RESOLVED = false; + } + + if (!qry->flags.CACHED) { + if (request->state & KR_STATE_FAIL) { + if (++request->count_fail_row > KR_CONSUME_FAIL_ROW_LIMIT) { + if (kr_log_is_debug(RESOLVER, request)) { /* logging optimization */ + kr_log_req(request, 0, 2, RESOLVER, + "=> too many failures in a row, " + "bail out (mitigation for NXNSAttack " + "CVE-2020-12667)\n"); + } + if (!qry->flags.NO_NS_FOUND) { + qry->flags.NO_NS_FOUND = true; + return KR_STATE_PRODUCE; + } + return KR_STATE_FAIL; + } + } else { + request->count_fail_row = 0; + } + } + + /* Pop query if resolved. */ + if (request->state == KR_STATE_YIELD) { + return KR_STATE_PRODUCE; /* Requery */ + } else if (qry->flags.RESOLVED) { + kr_rplan_pop(rplan, qry); + } else if (!tried_tcp && (qry->flags.TCP)) { + return KR_STATE_PRODUCE; /* Requery over TCP */ + } else { /* Clear query flags for next attempt */ + qry->flags.CACHED = false; + if (!request->options.TCP) { + qry->flags.TCP = false; + } + } + + ITERATE_LAYERS(request, qry, reset); + + /* Do not finish with bogus answer. */ + if (qry->flags.DNSSEC_BOGUS) { + if (qry->flags.FORWARD || qry->flags.STUB) { + return KR_STATE_FAIL; + } + /* Other servers might not have broken DNSSEC. */ + qry->flags.DNSSEC_BOGUS = false; + return KR_STATE_PRODUCE; + } + + return kr_rplan_empty(&request->rplan) ? KR_STATE_DONE : KR_STATE_PRODUCE; +} + +/** @internal Spawn subrequest in current zone cut (no minimization or lookup). */ +static struct kr_query *zone_cut_subreq(struct kr_rplan *rplan, struct kr_query *parent, + const knot_dname_t *qname, uint16_t qtype) +{ + struct kr_query *next = kr_rplan_push(rplan, parent, qname, parent->sclass, qtype); + if (!next) { + return NULL; + } + kr_zonecut_set(&next->zone_cut, parent->zone_cut.name); + if (kr_zonecut_copy(&next->zone_cut, &parent->zone_cut) != 0 || + kr_zonecut_copy_trust(&next->zone_cut, &parent->zone_cut) != 0) { + return NULL; + } + next->flags.NO_MINIMIZE = true; + if (parent->flags.DNSSEC_WANT) { + next->flags.DNSSEC_WANT = true; + } + return next; +} + +static int forward_trust_chain_check(struct kr_request *request, struct kr_query *qry, bool resume) +{ + struct kr_rplan *rplan = &request->rplan; + trie_t *trust_anchors = request->ctx->trust_anchors; + trie_t *negative_anchors = request->ctx->negative_anchors; + + if (qry->parent != NULL && + !(qry->forward_flags.CNAME) && + !(qry->flags.DNS64_MARK) && + knot_dname_in_bailiwick(qry->zone_cut.name, qry->parent->zone_cut.name) >= 0) { + return KR_STATE_PRODUCE; + } + + if (kr_fails_assert(qry->flags.FORWARD)) + return KR_STATE_FAIL; + + if (!trust_anchors) { + qry->flags.AWAIT_CUT = false; + return KR_STATE_PRODUCE; + } + + if (qry->flags.DNSSEC_INSECURE) { + qry->flags.AWAIT_CUT = false; + return KR_STATE_PRODUCE; + } + + if (qry->forward_flags.NO_MINIMIZE) { + qry->flags.AWAIT_CUT = false; + return KR_STATE_PRODUCE; + } + + const knot_dname_t *start_name = qry->sname; + if ((qry->flags.AWAIT_CUT) && !resume) { + qry->flags.AWAIT_CUT = false; + const knot_dname_t *longest_ta = kr_ta_closest(request->ctx, qry->sname, qry->stype); + if (longest_ta) { + start_name = longest_ta; + qry->zone_cut.name = knot_dname_copy(start_name, qry->zone_cut.pool); + qry->flags.DNSSEC_WANT = true; + } else { + qry->flags.DNSSEC_WANT = false; + return KR_STATE_PRODUCE; + } + } + + bool has_ta = (qry->zone_cut.trust_anchor != NULL); + knot_dname_t *ta_name = (has_ta ? qry->zone_cut.trust_anchor->owner : NULL); + bool refetch_ta = (!has_ta || !knot_dname_is_equal(qry->zone_cut.name, ta_name)); + bool is_dnskey_subreq = kr_rplan_satisfies(qry, ta_name, KNOT_CLASS_IN, KNOT_RRTYPE_DNSKEY); + bool refetch_key = has_ta && (!qry->zone_cut.key || !knot_dname_is_equal(ta_name, qry->zone_cut.key->owner)); + if (refetch_key && !is_dnskey_subreq) { + struct kr_query *next = zone_cut_subreq(rplan, qry, ta_name, KNOT_RRTYPE_DNSKEY); + if (!next) { + return KR_STATE_FAIL; + } + return KR_STATE_DONE; + } + + int name_offset = 1; + const knot_dname_t *wanted_name; + bool nods, ds_req, ns_req, minimized, ns_exist; + do { + wanted_name = start_name; + ds_req = false; + ns_req = false; + ns_exist = true; + + int cut_labels = knot_dname_labels(qry->zone_cut.name, NULL); + int wanted_name_labels = knot_dname_labels(wanted_name, NULL); + while (wanted_name[0] && wanted_name_labels > cut_labels + name_offset) { + wanted_name = knot_wire_next_label(wanted_name, NULL); + wanted_name_labels -= 1; + } + minimized = (wanted_name != qry->sname); + + for (int i = 0; i < request->rplan.resolved.len; ++i) { + struct kr_query *q = request->rplan.resolved.at[i]; + if (q->parent == qry && + q->sclass == qry->sclass && + (q->stype == KNOT_RRTYPE_DS || q->stype == KNOT_RRTYPE_NS) && + knot_dname_is_equal(q->sname, wanted_name)) { + if (q->stype == KNOT_RRTYPE_DS) { + ds_req = true; + if (q->flags.CNAME) { + ns_exist = false; + } else if (!(q->flags.DNSSEC_OPTOUT)) { + int ret = kr_dnssec_matches_name_and_type(&request->auth_selected, q->uid, + wanted_name, KNOT_RRTYPE_NS); + ns_exist = (ret == kr_ok()); + } + } else { + if (q->flags.CNAME) { + ns_exist = false; + } + ns_req = true; + } + } + } + + if (ds_req && ns_exist && !ns_req && (minimized || resume)) { + struct kr_query *next = zone_cut_subreq(rplan, qry, wanted_name, + KNOT_RRTYPE_NS); + if (!next) { + return KR_STATE_FAIL; + } + return KR_STATE_DONE; + } + + if (qry->parent == NULL && (qry->flags.CNAME) && + ds_req && ns_req) { + return KR_STATE_PRODUCE; + } + + /* set `nods` */ + if ((qry->stype == KNOT_RRTYPE_DS) && + knot_dname_is_equal(wanted_name, qry->sname)) { + nods = true; + } else if (resume && !ds_req) { + nods = false; + } else if (!minimized && qry->stype != KNOT_RRTYPE_DNSKEY) { + nods = true; + } else { + nods = ds_req; + } + name_offset += 1; + } while (ds_req && (ns_req || !ns_exist) && minimized); + + /* Disable DNSSEC if it enters NTA. */ + if (kr_ta_get(negative_anchors, wanted_name)){ + VERBOSE_MSG(qry, ">< negative TA, going insecure\n"); + qry->flags.DNSSEC_WANT = false; + } + + /* Enable DNSSEC if enters a new island of trust. */ + bool want_secure = (qry->flags.DNSSEC_WANT) && + !knot_wire_get_cd(request->qsource.packet->wire); + if (!(qry->flags.DNSSEC_WANT) && + !knot_wire_get_cd(request->qsource.packet->wire) && + kr_ta_get(trust_anchors, wanted_name)) { + qry->flags.DNSSEC_WANT = true; + want_secure = true; + if (kr_log_is_debug_qry(RESOLVER, qry)) { + KR_DNAME_GET_STR(qname_str, wanted_name); + VERBOSE_MSG(qry, ">< TA: '%s'\n", qname_str); + } + } + + if (want_secure && !qry->zone_cut.trust_anchor) { + knot_rrset_t *ta_rr = kr_ta_get(trust_anchors, wanted_name); + if (!ta_rr) { + char name[] = "\0"; + ta_rr = kr_ta_get(trust_anchors, (knot_dname_t*)name); + } + if (ta_rr) { + qry->zone_cut.trust_anchor = knot_rrset_copy(ta_rr, qry->zone_cut.pool); + } + } + + has_ta = (qry->zone_cut.trust_anchor != NULL); + ta_name = (has_ta ? qry->zone_cut.trust_anchor->owner : NULL); + refetch_ta = (!has_ta || !knot_dname_is_equal(wanted_name, ta_name)); + if (!nods && want_secure && refetch_ta) { + struct kr_query *next = zone_cut_subreq(rplan, qry, wanted_name, + KNOT_RRTYPE_DS); + if (!next) { + return KR_STATE_FAIL; + } + return KR_STATE_DONE; + } + + /* Try to fetch missing DNSKEY. + * Do not fetch if this is a DNSKEY subrequest to avoid circular dependency. */ + is_dnskey_subreq = kr_rplan_satisfies(qry, ta_name, KNOT_CLASS_IN, KNOT_RRTYPE_DNSKEY); + refetch_key = has_ta && (!qry->zone_cut.key || !knot_dname_is_equal(ta_name, qry->zone_cut.key->owner)); + if (want_secure && refetch_key && !is_dnskey_subreq) { + struct kr_query *next = zone_cut_subreq(rplan, qry, ta_name, KNOT_RRTYPE_DNSKEY); + if (!next) { + return KR_STATE_FAIL; + } + return KR_STATE_DONE; + } + + return KR_STATE_PRODUCE; +} + +/* @todo: Validator refactoring, keep this in driver for now. */ +static int trust_chain_check(struct kr_request *request, struct kr_query *qry) +{ + struct kr_rplan *rplan = &request->rplan; + trie_t *trust_anchors = request->ctx->trust_anchors; + trie_t *negative_anchors = request->ctx->negative_anchors; + + /* Disable DNSSEC if it enters NTA. */ + if (kr_ta_get(negative_anchors, qry->zone_cut.name)){ + VERBOSE_MSG(qry, ">< negative TA, going insecure\n"); + qry->flags.DNSSEC_WANT = false; + qry->flags.DNSSEC_INSECURE = true; + } + if (qry->flags.DNSSEC_NODS) { + /* This is the next query iteration with minimized qname. + * At previous iteration DS non-existence has been proven */ + VERBOSE_MSG(qry, "<= DS doesn't exist, going insecure\n"); + qry->flags.DNSSEC_NODS = false; + qry->flags.DNSSEC_WANT = false; + qry->flags.DNSSEC_INSECURE = true; + } + /* Enable DNSSEC if entering a new (or different) island of trust, + * and update the TA RRset if required. */ + const bool has_cd = knot_wire_get_cd(request->qsource.packet->wire); + knot_rrset_t *ta_rr = kr_ta_get(trust_anchors, qry->zone_cut.name); + if (!has_cd && ta_rr) { + qry->flags.DNSSEC_WANT = true; + if (qry->zone_cut.trust_anchor == NULL + || !knot_dname_is_equal(qry->zone_cut.trust_anchor->owner, qry->zone_cut.name)) { + mm_free(qry->zone_cut.pool, qry->zone_cut.trust_anchor); + qry->zone_cut.trust_anchor = knot_rrset_copy(ta_rr, qry->zone_cut.pool); + + if (kr_log_is_debug_qry(RESOLVER, qry)) { + KR_DNAME_GET_STR(qname_str, ta_rr->owner); + VERBOSE_MSG(qry, ">< TA: '%s'\n", qname_str); + } + } + } + + /* Try to fetch missing DS (from above the cut). */ + const bool has_ta = (qry->zone_cut.trust_anchor != NULL); + const knot_dname_t *ta_name = (has_ta ? qry->zone_cut.trust_anchor->owner : NULL); + const bool refetch_ta = !has_ta || !knot_dname_is_equal(qry->zone_cut.name, ta_name); + const bool want_secure = qry->flags.DNSSEC_WANT && !has_cd; + if (want_secure && refetch_ta) { + /* @todo we could fetch the information from the parent cut, but we don't remember that now */ + struct kr_query *next = kr_rplan_push(rplan, qry, qry->zone_cut.name, qry->sclass, KNOT_RRTYPE_DS); + if (!next) { + return KR_STATE_FAIL; + } + next->flags.AWAIT_CUT = true; + next->flags.DNSSEC_WANT = true; + return KR_STATE_DONE; + } + /* Try to fetch missing DNSKEY (either missing or above current cut). + * Do not fetch if this is a DNSKEY subrequest to avoid circular dependency. */ + const bool is_dnskey_subreq = kr_rplan_satisfies(qry, ta_name, KNOT_CLASS_IN, KNOT_RRTYPE_DNSKEY); + const bool refetch_key = has_ta && (!qry->zone_cut.key || !knot_dname_is_equal(ta_name, qry->zone_cut.key->owner)); + if (want_secure && refetch_key && !is_dnskey_subreq) { + struct kr_query *next = zone_cut_subreq(rplan, qry, ta_name, KNOT_RRTYPE_DNSKEY); + if (!next) { + return KR_STATE_FAIL; + } + return KR_STATE_DONE; + } + + return KR_STATE_PRODUCE; +} + +/** @internal Check current zone cut status and credibility, spawn subrequests if needed. */ +static int zone_cut_check(struct kr_request *request, struct kr_query *qry, knot_pkt_t *packet) +/* TODO: using cache on this point in this way just isn't nice; remove in time */ +{ + /* Stub mode, just forward and do not solve cut. */ + if (qry->flags.STUB) { + return KR_STATE_PRODUCE; + } + + /* Forwarding to upstream resolver mode. + * Since forwarding targets already are in qry->ns - + * cut fetching is not needed. */ + if (qry->flags.FORWARD) { + return forward_trust_chain_check(request, qry, false); + } + if (!(qry->flags.AWAIT_CUT)) { + /* The query was resolved from cache. + * Spawn DS \ DNSKEY requests if needed and exit */ + return trust_chain_check(request, qry); + } + + /* The query wasn't resolved from cache, + * now it's the time to look up closest zone cut from cache. */ + struct kr_cache *cache = &request->ctx->cache; + if (!kr_cache_is_open(cache)) { + int ret = kr_zonecut_set_sbelt(request->ctx, &qry->zone_cut); + if (ret != 0) { + return KR_STATE_FAIL; + } + VERBOSE_MSG(qry, "=> no cache open, using root hints\n"); + qry->flags.AWAIT_CUT = false; + return KR_STATE_DONE; + } + + const knot_dname_t *requested_name = qry->sname; + /* If at/subdomain of parent zone cut, start from its encloser. + * This is for case when we get to a dead end + * (and need glue from parent), or DS refetch. */ + if (qry->parent) { + const knot_dname_t *parent = qry->parent->zone_cut.name; + if (parent[0] != '\0' + && knot_dname_in_bailiwick(qry->sname, parent) >= 0) { + requested_name = knot_wire_next_label(parent, NULL); + } + } else if ((qry->stype == KNOT_RRTYPE_DS) && (qry->sname[0] != '\0')) { + /* If this is explicit DS query, start from encloser too. */ + requested_name = knot_wire_next_label(requested_name, NULL); + } + + int state = KR_STATE_FAIL; + do { + state = ns_fetch_cut(qry, requested_name, request, packet); + if (state == KR_STATE_DONE || (state & KR_STATE_FAIL)) { + return state; + } else if (state == KR_STATE_CONSUME) { + requested_name = knot_wire_next_label(requested_name, NULL); + } + } while (state == KR_STATE_CONSUME); + + /* Update minimized QNAME if zone cut changed */ + if (qry->zone_cut.name && qry->zone_cut.name[0] != '\0' && !(qry->flags.NO_MINIMIZE)) { + if (kr_make_query(qry, packet) != 0) { + return KR_STATE_FAIL; + } + } + qry->flags.AWAIT_CUT = false; + + /* Check trust chain */ + return trust_chain_check(request, qry); +} + + +static int ns_resolve_addr(struct kr_query *qry, struct kr_request *param, struct kr_transport *transport, uint16_t next_type) +{ + struct kr_rplan *rplan = ¶m->rplan; + struct kr_context *ctx = param->ctx; + + + /* Start NS queries from root, to avoid certain cases + * where a NS drops out of cache and the rest is unavailable, + * this would lead to dependency loop in current zone cut. + */ + + /* Bail out if the query is already pending or dependency loop. */ + if (!next_type || kr_rplan_satisfies(qry->parent, transport->ns_name, KNOT_CLASS_IN, next_type)) { + /* Fall back to SBELT if root server query fails. */ + if (!next_type && qry->zone_cut.name[0] == '\0') { + VERBOSE_MSG(qry, "=> fallback to root hints\n"); + kr_zonecut_set_sbelt(ctx, &qry->zone_cut); + return kr_error(EAGAIN); + } + /* No IPv4 nor IPv6, flag server as unusable. */ + VERBOSE_MSG(qry, "=> unresolvable NS address, bailing out\n"); + kr_zonecut_del_all(&qry->zone_cut, transport->ns_name); + return kr_error(EHOSTUNREACH); + } + /* Push new query to the resolution plan */ + struct kr_query *next = + kr_rplan_push(rplan, qry, transport->ns_name, KNOT_CLASS_IN, next_type); + if (!next) { + return kr_error(ENOMEM); + } + next->flags.NONAUTH = true; + + /* At the root level with no NS addresses, add SBELT subrequest. */ + int ret = 0; + if (qry->zone_cut.name[0] == '\0') { + ret = kr_zonecut_set_sbelt(ctx, &next->zone_cut); + if (ret == 0) { /* Copy TA and key since it's the same cut to avoid lookup. */ + kr_zonecut_copy_trust(&next->zone_cut, &qry->zone_cut); + kr_zonecut_set_sbelt(ctx, &qry->zone_cut); /* Add SBELT to parent in case query fails. */ + } + } else { + next->flags.AWAIT_CUT = true; + } + + if (ret == 0) { + if (next_type == KNOT_RRTYPE_AAAA) { + qry->flags.AWAIT_IPV6 = true; + } else { + qry->flags.AWAIT_IPV4 = true; + } + } + + return ret; +} + +int kr_resolve_produce(struct kr_request *request, struct kr_transport **transport, knot_pkt_t *packet) +{ + struct kr_rplan *rplan = &request->rplan; + + /* No query left for resolution */ + if (kr_rplan_empty(rplan)) { + return KR_STATE_FAIL; + } + + struct kr_query *qry = array_tail(rplan->pending); + + /* Initialize server selection */ + if (!qry->server_selection.initialized) { + kr_server_selection_init(qry); + } + + /* If we have deferred answers, resume them. */ + if (qry->deferred != NULL) { + /* @todo: Refactoring validator, check trust chain before resuming. */ + int state = 0; + if (((qry->flags.FORWARD) == 0) || + ((qry->stype == KNOT_RRTYPE_DS) && (qry->flags.CNAME))) { + state = trust_chain_check(request, qry); + } else { + state = forward_trust_chain_check(request, qry, true); + } + + switch(state) { + case KR_STATE_FAIL: return KR_STATE_FAIL; + case KR_STATE_DONE: return KR_STATE_PRODUCE; + default: break; + } + VERBOSE_MSG(qry, "=> resuming yielded answer\n"); + struct kr_layer_pickle *pickle = qry->deferred; + request->state = KR_STATE_YIELD; + set_yield(&request->answ_selected, qry->uid, false); + set_yield(&request->auth_selected, qry->uid, false); + RESUME_LAYERS(layer_id(request, pickle->api), request, qry, consume, pickle->pkt); + if (request->state != KR_STATE_YIELD) { + /* No new deferred answers, take the next */ + qry->deferred = pickle->next; + } + } else { + /* Caller is interested in always tracking a zone cut, even if the answer is cached + * this is normally not required, and incurs another cache lookups for cached answer. */ + if (qry->flags.ALWAYS_CUT) { + if (!(qry->flags.STUB)) { + switch(zone_cut_check(request, qry, packet)) { + case KR_STATE_FAIL: return KR_STATE_FAIL; + case KR_STATE_DONE: return KR_STATE_PRODUCE; + default: break; + } + } + } + /* Resolve current query and produce dependent or finish */ + request->state = KR_STATE_PRODUCE; + ITERATE_LAYERS(request, qry, produce, packet); + if (!(request->state & KR_STATE_FAIL) && knot_wire_get_qr(packet->wire)) { + /* Produced an answer from cache, consume it. */ + qry->secret = 0; + request->state = KR_STATE_CONSUME; + ITERATE_LAYERS(request, qry, consume, packet); + } + } + switch(request->state) { + case KR_STATE_FAIL: return request->state; + case KR_STATE_CONSUME: break; + case KR_STATE_DONE: + default: /* Current query is done */ + if (qry->flags.RESOLVED && request->state != KR_STATE_YIELD) { + kr_rplan_pop(rplan, qry); + } + ITERATE_LAYERS(request, qry, reset); + return kr_rplan_empty(rplan) ? KR_STATE_DONE : KR_STATE_PRODUCE; + } + + + /* This query has RD=0 or is ANY, stop here. */ + if (qry->stype == KNOT_RRTYPE_ANY || + !knot_wire_get_rd(request->qsource.packet->wire)) { + VERBOSE_MSG(qry, "=> qtype is ANY or RD=0, bail out\n"); + return KR_STATE_FAIL; + } + + /* Update zone cut, spawn new subrequests. */ + if (!(qry->flags.STUB)) { + int state = zone_cut_check(request, qry, packet); + switch(state) { + case KR_STATE_FAIL: return KR_STATE_FAIL; + case KR_STATE_DONE: return KR_STATE_PRODUCE; + default: break; + } + } + + + const struct kr_qflags qflg = qry->flags; + const bool retry = qflg.TCP || qflg.BADCOOKIE_AGAIN; + if (!qflg.FORWARD && !qflg.STUB && !retry) { /* Keep NS when requerying/stub/badcookie. */ + /* Root DNSKEY must be fetched from the hints to avoid chicken and egg problem. */ + if (qry->sname[0] == '\0' && qry->stype == KNOT_RRTYPE_DNSKEY) { + kr_zonecut_set_sbelt(request->ctx, &qry->zone_cut); + } + } + + qry->server_selection.choose_transport(qry, transport); + + if (*transport == NULL) { + /* Properly signal to serve_stale module. */ + if (qry->flags.NO_NS_FOUND) { + ITERATE_LAYERS(request, qry, reset); + kr_rplan_pop(rplan, qry); + return KR_STATE_FAIL; + } else { + /* FIXME: This is probably quite inefficient: + * we go through the whole qr_task_step loop just because of the serve_stale + * module which might not even be loaded. */ + qry->flags.NO_NS_FOUND = true; + return KR_STATE_PRODUCE; + } + } + + if ((*transport)->protocol == KR_TRANSPORT_RESOLVE_A || (*transport)->protocol == KR_TRANSPORT_RESOLVE_AAAA) { + uint16_t type = (*transport)->protocol == KR_TRANSPORT_RESOLVE_A ? KNOT_RRTYPE_A : KNOT_RRTYPE_AAAA; + ns_resolve_addr(qry, qry->request, *transport, type); + ITERATE_LAYERS(request, qry, reset); + return KR_STATE_PRODUCE; + } + + /* Randomize query case (if not in not turned off) */ + qry->secret = qry->flags.NO_0X20 ? 0 : kr_rand_bytes(sizeof(qry->secret)); + knot_dname_t *qname_raw = kr_pkt_qname_raw(packet); + randomized_qname_case(qname_raw, qry->secret); + + /* + * Additional query is going to be finalized when calling + * kr_resolve_checkout(). + */ + qry->timestamp_mono = kr_now(); + return request->state; +} + +#if ENABLE_COOKIES +/** Update DNS cookie data in packet. */ +static bool outbound_request_update_cookies(struct kr_request *req, + const struct sockaddr *src, + const struct sockaddr *dst) +{ + if (kr_fails_assert(req)) + return false; + + /* RFC7873 4.1 strongly requires server address. */ + if (!dst) + return false; + + struct kr_cookie_settings *clnt_sett = &req->ctx->cookie_ctx.clnt; + + /* Cookies disabled or packet has no EDNS section. */ + if (!clnt_sett->enabled) + return true; + + /* + * RFC7873 4.1 recommends using also the client address. The matter is + * also discussed in section 6. + */ + + kr_request_put_cookie(&clnt_sett->current, req->ctx->cache_cookie, + src, dst, req); + + return true; +} +#endif /* ENABLE_COOKIES */ + +int kr_resolve_checkout(struct kr_request *request, const struct sockaddr *src, + struct kr_transport *transport, knot_pkt_t *packet) +{ + /* @todo: Update documentation if this function becomes approved. */ + + struct kr_rplan *rplan = &request->rplan; + + if (knot_wire_get_qr(packet->wire) != 0) { + return kr_ok(); + } + + /* No query left for resolution */ + if (kr_rplan_empty(rplan)) { + return kr_error(EINVAL); + } + struct kr_query *qry = array_tail(rplan->pending); + +#if ENABLE_COOKIES + /* Update DNS cookies in request. */ + if (type == SOCK_DGRAM) { /* @todo: Add cookies also over TCP? */ + /* + * The actual server IP address is needed before generating the + * actual cookie. If we don't know the server address then we + * also don't know the actual cookie size. + */ + if (!outbound_request_update_cookies(request, src, &transport->address.ip)) { + return kr_error(EINVAL); + } + } +#endif /* ENABLE_COOKIES */ + + int ret = query_finalize(request, qry, packet); + if (ret != 0) { + return kr_error(EINVAL); + } + + /* Track changes in minimization secret to enable/disable minimization */ + uint32_t old_minimization_secret = qry->secret; + + /* Run the checkout layers and cancel on failure. + * The checkout layer doesn't persist the state, so canceled subrequests + * don't affect the resolution or rest of the processing. */ + int type = -1; + switch(transport->protocol) { + case KR_TRANSPORT_UDP: + type = SOCK_DGRAM; + break; + case KR_TRANSPORT_TCP: + case KR_TRANSPORT_TLS: + type = SOCK_STREAM; + break; + default: + kr_assert(false); + } + int state = request->state; + ITERATE_LAYERS(request, qry, checkout, packet, &transport->address.ip, type); + if (request->state & KR_STATE_FAIL) { + request->state = state; /* Restore */ + return kr_error(ECANCELED); + } + + /* Randomize query case (if secret changed) */ + knot_dname_t *qname_raw = kr_pkt_qname_raw(packet); + if (qry->secret != old_minimization_secret) { + randomized_qname_case(qname_raw, qry->secret); + } + + /* Write down OPT unless in safemode */ + if (!(qry->flags.NO_EDNS)) { + /* TLS padding */ + if (transport->protocol == KR_TRANSPORT_TLS) { + size_t padding_size = edns_padding_option_size(request->ctx->tls_padding); + ret = knot_pkt_reserve(packet, padding_size); + if (ret) + return kr_error(EINVAL); + ret = pkt_padding(packet, request->ctx->tls_padding); + if (ret) + return kr_error(EINVAL); + } + + ret = edns_put(packet, true); + if (ret != 0) { + return kr_error(EINVAL); + } + } + + if (kr_log_is_debug_qry(RESOLVER, qry)) { + KR_DNAME_GET_STR(qname_str, knot_pkt_qname(packet)); + KR_DNAME_GET_STR(ns_name, transport->ns_name); + KR_DNAME_GET_STR(zonecut_str, qry->zone_cut.name); + KR_RRTYPE_GET_STR(type_str, knot_pkt_qtype(packet)); + const char *ns_str = kr_straddr(&transport->address.ip); + + VERBOSE_MSG(qry, + "=> id: '%05u' querying: '%s'@'%s' zone cut: '%s' " + "qname: '%s' qtype: '%s' proto: '%s'\n", + qry->id, ns_name, ns_str ? ns_str : "", zonecut_str, + qname_str, type_str, (qry->flags.TCP) ? "tcp" : "udp"); + } + + return kr_ok(); +} + +int kr_resolve_finish(struct kr_request *request, int state) +{ + request->state = state; + /* Finalize answer and construct whole wire-format (unless dropping). */ + knot_pkt_t *answer = kr_request_ensure_answer(request); + if (answer) { + ITERATE_LAYERS(request, NULL, answer_finalize); + answer_finalize(request); + + /* Defensive style, in case someone has forgotten. + * Beware: non-empty answers do make sense even with SERVFAIL case, etc. */ + if (request->state != KR_STATE_DONE) { + uint8_t *wire = answer->wire; + switch (knot_wire_get_rcode(wire)) { + case KNOT_RCODE_NOERROR: + case KNOT_RCODE_NXDOMAIN: + knot_wire_clear_ad(wire); + knot_wire_clear_aa(wire); + knot_wire_set_rcode(wire, KNOT_RCODE_SERVFAIL); + } + } + } + + ITERATE_LAYERS(request, NULL, finish); + + struct kr_rplan *rplan = &request->rplan; + struct kr_query *last = kr_rplan_last(rplan); + VERBOSE_MSG(last, "finished in state: %d, queries: %zu, mempool: %zu B\n", + request->state, rplan->resolved.len, (size_t) mp_total_size(request->pool.ctx)); + + /* Trace request finish */ + if (request->trace_finish) { + request->trace_finish(request); + } + + /* Uninstall all tracepoints */ + request->trace_finish = NULL; + request->trace_log = NULL; + + return KR_STATE_DONE; +} + +struct kr_rplan *kr_resolve_plan(struct kr_request *request) +{ + if (request) { + return &request->rplan; + } + return NULL; +} + +knot_mm_t *kr_resolve_pool(struct kr_request *request) +{ + if (request) { + return &request->pool; + } + return NULL; +} + +static int ede_priority(int info_code) +{ + switch(info_code) { + case KNOT_EDNS_EDE_DNSKEY_BIT: + case KNOT_EDNS_EDE_DNSKEY_MISS: + case KNOT_EDNS_EDE_SIG_EXPIRED: + case KNOT_EDNS_EDE_SIG_NOTYET: + case KNOT_EDNS_EDE_RRSIG_MISS: + case KNOT_EDNS_EDE_NSEC_MISS: + return 900; /* Specific DNSSEC failures */ + case KNOT_EDNS_EDE_BOGUS: + return 800; /* Generic DNSSEC failure */ + case KNOT_EDNS_EDE_FORGED: + case KNOT_EDNS_EDE_FILTERED: + return 700; /* Considered hard fail by firefox */ + case KNOT_EDNS_EDE_PROHIBITED: + case KNOT_EDNS_EDE_BLOCKED: + case KNOT_EDNS_EDE_CENSORED: + return 600; /* Policy related */ + case KNOT_EDNS_EDE_DNSKEY_ALG: + case KNOT_EDNS_EDE_DS_DIGEST: + return 500; /* Non-critical DNSSEC issues */ + case KNOT_EDNS_EDE_STALE: + case KNOT_EDNS_EDE_STALE_NXD: + return 300; /* Serve-stale answers. */ + case KNOT_EDNS_EDE_INDETERMINATE: + case KNOT_EDNS_EDE_CACHED_ERR: + case KNOT_EDNS_EDE_NOT_READY: + case KNOT_EDNS_EDE_NOTAUTH: + case KNOT_EDNS_EDE_NOTSUP: + case KNOT_EDNS_EDE_NREACH_AUTH: + case KNOT_EDNS_EDE_NETWORK: + case KNOT_EDNS_EDE_INV_DATA: + return 200; /* Assorted codes */ + case KNOT_EDNS_EDE_OTHER: + return 100; /* Most generic catch-all error */ + case KNOT_EDNS_EDE_NONE: + return 0; /* No error - allow overriding */ + default: + kr_assert(false); /* Unknown info_code */ + return 50; + } +} + +int kr_request_set_extended_error(struct kr_request *request, int info_code, const char *extra_text) +{ + if (kr_fails_assert(request)) + return KNOT_EDNS_EDE_NONE; + + struct kr_extended_error *ede = &request->extended_error; + + /* Clear any previously set error. */ + if (info_code == KNOT_EDNS_EDE_NONE) { + kr_assert(extra_text == NULL); + ede->info_code = KNOT_EDNS_EDE_NONE; + ede->extra_text = NULL; + return KNOT_EDNS_EDE_NONE; + } + + if (ede_priority(info_code) >= ede_priority(ede->info_code)) { + ede->info_code = info_code; + ede->extra_text = extra_text; + } + + return ede->info_code; +} + +#undef VERBOSE_MSG |