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-rw-r--r--lib/cache/entry_list.c293
1 files changed, 293 insertions, 0 deletions
diff --git a/lib/cache/entry_list.c b/lib/cache/entry_list.c
new file mode 100644
index 0000000..6a5001c
--- /dev/null
+++ b/lib/cache/entry_list.c
@@ -0,0 +1,293 @@
+/* Copyright (C) 2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+
+ This program is free software: you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation, either version 3 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see <https://www.gnu.org/licenses/>.
+ */
+
+/** @file
+ * Implementation of chaining in struct entry_h. Prototypes in ./impl.h
+ */
+
+#include "lib/cache/impl.h"
+#include "lib/utils.h"
+
+
+static int entry_h_len(knot_db_val_t val);
+
+
+void entry_list_memcpy(struct entry_apex *ea, entry_list_t list)
+{
+ assert(ea);
+ memset(ea, 0, offsetof(struct entry_apex, data));
+ ea->has_ns = list[EL_NS ].len;
+ ea->has_cname = list[EL_CNAME ].len;
+ ea->has_dname = list[EL_DNAME ].len;
+ for (int i = 0; i < ENTRY_APEX_NSECS_CNT; ++i) {
+ ea->nsecs[i] = list[i].len == 0 ? 0 :
+ (list[i].len == 4 ? 1 : 3);
+ }
+ uint8_t *it = ea->data;
+ for (int i = 0; i < EL_LENGTH; ++i) {
+ if (list[i].data) {
+ memcpy(it, list[i].data, list[i].len);
+ /* LATER(optim.): coalesce consecutive writes? */
+ } else {
+ list[i].data = it;
+ }
+ it += to_even(list[i].len);
+ }
+}
+
+int entry_list_parse(const knot_db_val_t val, entry_list_t list)
+{
+ const bool ok = val.data && val.len && list;
+ if (!ok) {
+ assert(!EINVAL);
+ return kr_error(EINVAL);
+ }
+ /* Parse the apex itself (nsec parameters). */
+ const struct entry_apex *ea = entry_apex_consistent(val);
+ if (!ea) {
+ return kr_error(EILSEQ);
+ }
+ const uint8_t *it = ea->data,
+ *it_bound = knot_db_val_bound(val);
+ for (int i = 0; i < ENTRY_APEX_NSECS_CNT; ++i) {
+ if (it > it_bound) {
+ return kr_error(EILSEQ);
+ }
+ list[i].data = (void *)it;
+ switch (ea->nsecs[i]) {
+ case 0:
+ list[i].len = 0;
+ break;
+ case 1:
+ list[i].len = sizeof(uint32_t); /* just timestamp */
+ break;
+ case 3: { /* timestamp + NSEC3PARAM wire */
+ if (it + sizeof(uint32_t) + 4 > it_bound) {
+ return kr_error(EILSEQ);
+ }
+ list[i].len = sizeof(uint32_t)
+ + nsec_p_rdlen(it + sizeof(uint32_t));
+ break;
+ }
+ default:
+ return kr_error(EILSEQ);
+ };
+ it += to_even(list[i].len);
+ }
+ /* Parse every entry_h. */
+ for (int i = ENTRY_APEX_NSECS_CNT; i < EL_LENGTH; ++i) {
+ list[i].data = (void *)it;
+ bool has_type;
+ switch (i) {
+ case EL_NS: has_type = ea->has_ns; break;
+ case EL_CNAME: has_type = ea->has_cname; break;
+ case EL_DNAME: has_type = ea->has_dname; break;
+ default: assert(false); return kr_error(EINVAL); /* something very bad */
+ }
+ if (!has_type) {
+ list[i].len = 0;
+ continue;
+ }
+ if (it >= it_bound) {
+ assert(!EILSEQ);
+ return kr_error(EILSEQ);
+ }
+ const int len = entry_h_len(
+ (knot_db_val_t){ .data = (void *)it, .len = it_bound - it });
+ if (len < 0) {
+ assert(false);
+ return kr_error(len);
+ }
+ list[i].len = len;
+ it += to_even(len);
+ }
+ assert(it == it_bound);
+ return kr_ok();
+}
+
+/** Given a valid entry header, find its length (i.e. offset of the next entry).
+ * \param val The beginning of the data and the bound (read only).
+ */
+static int entry_h_len(const knot_db_val_t val)
+{
+ const bool ok = val.data && ((ssize_t)val.len) > 0;
+ if (!ok) return kr_error(EINVAL);
+ const struct entry_h *eh = val.data;
+ const uint8_t *d = eh->data; /* iterates over the data in entry */
+ const uint8_t *data_bound = knot_db_val_bound(val);
+ if (d >= data_bound) return kr_error(EILSEQ);
+ if (!eh->is_packet) { /* Positive RRset + its RRsig set (may be empty). */
+ int sets = 2;
+ while (sets-- > 0) {
+ d += rdataset_dematerialized_size(d);
+ if (d > data_bound) {
+ assert(!EILSEQ);
+ return kr_error(EILSEQ);
+ }
+ }
+ } else { /* A "packet" (opaque ATM). */
+ uint16_t len;
+ if (d + sizeof(len) > data_bound) return kr_error(EILSEQ);
+ memcpy(&len, d, sizeof(len));
+ d += 2 + to_even(len);
+ }
+ if (d > data_bound) {
+ assert(!EILSEQ);
+ return kr_error(EILSEQ);
+ }
+ return d - (uint8_t *)val.data;
+}
+
+struct entry_apex * entry_apex_consistent(knot_db_val_t val)
+{
+ //XXX: check lengths, etc.
+ return val.data;
+}
+
+/* See the header file. */
+int entry_h_seek(knot_db_val_t *val, uint16_t type)
+{
+ int i = -1;
+ switch (type) {
+ case KNOT_RRTYPE_NS: i = EL_NS; break;
+ case KNOT_RRTYPE_CNAME: i = EL_CNAME; break;
+ case KNOT_RRTYPE_DNAME: i = EL_DNAME; break;
+ default: return kr_ok();
+ }
+
+ entry_list_t el;
+ int ret = entry_list_parse(*val, el);
+ if (ret) return ret;
+ *val = el[i];
+ return val->len ? kr_ok() : kr_error(ENOENT);
+}
+
+static int cache_write_or_clear(struct kr_cache *cache, const knot_db_val_t *key,
+ knot_db_val_t *val, const struct kr_query *qry)
+{
+ int ret = cache_op(cache, write, key, val, 1);
+ if (!ret) return kr_ok();
+ /* Clear cache if overfull. It's nontrivial to do better with LMDB.
+ * LATER: some garbage-collection mechanism. */
+ if (ret == kr_error(ENOSPC)) {
+ ret = kr_cache_clear(cache);
+ const char *msg = "[cache] clearing because overfull, ret = %d\n";
+ if (ret) {
+ kr_log_error(msg, ret);
+ } else {
+ kr_log_info(msg, ret);
+ ret = kr_error(ENOSPC);
+ }
+ return ret;
+ }
+ VERBOSE_MSG(qry, "=> failed backend write, ret = %d\n", ret);
+ return kr_error(ret ? ret : ENOSPC);
+}
+
+
+/* See the header file. */
+int entry_h_splice(
+ knot_db_val_t *val_new_entry, uint8_t rank,
+ const knot_db_val_t key, const uint16_t ktype, const uint16_t type,
+ const knot_dname_t *owner/*log only*/,
+ const struct kr_query *qry, struct kr_cache *cache, uint32_t timestamp)
+{
+ //TODO: another review, perhaps incuding the API
+ const bool ok = val_new_entry && val_new_entry->len > 0;
+ if (!ok) {
+ assert(!EINVAL);
+ return kr_error(EINVAL);
+ }
+
+ int i_type;
+ switch (type) {
+ case KNOT_RRTYPE_NS: i_type = EL_NS; break;
+ case KNOT_RRTYPE_CNAME: i_type = EL_CNAME; break;
+ case KNOT_RRTYPE_DNAME: i_type = EL_DNAME; break;
+ default: i_type = 0;
+ }
+
+ /* Get eh_orig (original entry), and also el list if multi-entry case. */
+ const struct entry_h *eh_orig = NULL;
+ entry_list_t el;
+ int ret = -1;
+ if (!kr_rank_test(rank, KR_RANK_SECURE) || ktype == KNOT_RRTYPE_NS) {
+ knot_db_val_t val;
+ ret = cache_op(cache, read, &key, &val, 1);
+ if (i_type) {
+ if (!ret) ret = entry_list_parse(val, el);
+ if (ret) memset(el, 0, sizeof(el));
+ val = el[i_type];
+ }
+ /* val is on the entry, in either case (or error) */
+ if (!ret) {
+ eh_orig = entry_h_consistent(val, type);
+ }
+ } else {
+ /* We want to fully overwrite the entry, so don't even read it. */
+ memset(el, 0, sizeof(el));
+ }
+
+ if (!kr_rank_test(rank, KR_RANK_SECURE) && eh_orig) {
+ /* If equal rank was accepted, spoofing a *single* answer would be
+ * enough to e.g. override NS record in AUTHORITY section.
+ * This way they would have to hit the first answer
+ * (whenever TTL nears expiration).
+ * Stale-serving is NOT considered, but TTL 1 would be considered
+ * as expiring anyway, ... */
+ int32_t old_ttl = get_new_ttl(eh_orig, qry, NULL, 0, timestamp);
+ if (old_ttl > 0 && !is_expiring(eh_orig->ttl, old_ttl)
+ && rank <= eh_orig->rank) {
+ WITH_VERBOSE(qry) {
+ auto_free char *type_str = kr_rrtype_text(type),
+ *owner_str = kr_dname_text(owner);
+ VERBOSE_MSG(qry, "=> not overwriting %s %s\n",
+ type_str, owner_str);
+ }
+ return kr_error(EEXIST);
+ }
+ }
+
+ if (!i_type) {
+ /* The non-list types are trivial now. */
+ return cache_write_or_clear(cache, &key, val_new_entry, qry);
+ }
+ /* Now we're in trouble. In some cases, parts of data to be written
+ * is an lmdb entry that may be invalidated by our write request.
+ * (lmdb does even in-place updates!) Therefore we copy all into a buffer.
+ * (We don't bother deallocating from the mempool.)
+ * LATER(optim.): do this only when neccessary, or perhaps another approach.
+ * This is also complicated by the fact that the val_new_entry part
+ * is to be written *afterwards* by the caller.
+ */
+ el[i_type] = (knot_db_val_t){
+ .len = val_new_entry->len,
+ .data = NULL, /* perhaps unclear in the entry_h_splice() API */
+ };
+ knot_db_val_t val = {
+ .len = entry_list_serial_size(el),
+ .data = NULL,
+ };
+ void *buf = mm_alloc(&qry->request->pool, val.len);
+ entry_list_memcpy(buf, el);
+ ret = cache_write_or_clear(cache, &key, &val, qry);
+ if (ret) return kr_error(ret);
+ memcpy(val.data, buf, val.len); /* we also copy the "empty" space, but well... */
+ val_new_entry->data = (uint8_t *)val.data
+ + ((uint8_t *)el[i_type].data - (uint8_t *)buf);
+ return kr_ok();
+}
+
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