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-rw-r--r--src/lib/crypt/keyrot.c741
1 files changed, 741 insertions, 0 deletions
diff --git a/src/lib/crypt/keyrot.c b/src/lib/crypt/keyrot.c
new file mode 100644
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--- /dev/null
+++ b/src/lib/crypt/keyrot.c
@@ -0,0 +1,741 @@
+/*
+ * Ouroboros - Copyright (C) 2016 - 2026
+ *
+ * Data-plane key-rotation schedule (node/leaf keys, selector)
+ *
+ * Dimitri Staessens <dimitri@ouroboros.rocks>
+ * Sander Vrijders <sander@ouroboros.rocks>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public License
+ * version 2.1 as published by the Free Software Foundation.
+ *
+ * This library 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
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., http://www.fsf.org/about/contact/.
+ */
+
+#define _POSIX_C_SOURCE 200809L
+
+#include <config.h>
+
+#include <ouroboros/atomics.h>
+#include <ouroboros/crypt.h>
+#include <ouroboros/pthread.h>
+#include <ouroboros/rcu.h>
+
+#include "crypt/keyrot.h"
+
+#include <assert.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <string.h>
+
+/*
+ * Per-flow keys are addressed by (epoch, node, leaf) and derived as:
+ * root = per-batch HKDF PRK from the OAP exchange, wiped once expanded
+ * nodes = HKDF-Expand(root, "o7s-keyrot-node") -> KEY_NODE_COUNT keys
+ * leaf = HKDF-Expand(node, "o7s-keyrot-leaf"|dir|leaf) -> AEAD key
+ * The epoch is a small wrapping counter, carried in the selector, that picks
+ * the live batch; a Tier-2 OAP re-key advances it. The "dir" byte forks the
+ * leaf keys per direction.
+ *
+ * Concurrency: cur/prev batch pointers are published by a re-key and read on
+ * the data path under an rcu_guard (lock-free RCU with liburcu, else a per-
+ * keyrot rwlock). The per-batch TX counter is atomic, so the (epoch, counter)
+ * nonce is unique without serialising TX. Leaf caches are THREAD-LOCAL (an app
+ * writer and the FRCT retransmit timer never share cache state), keyed on a
+ * global batch id and direct-mapped.
+ */
+
+#define KR_WITHIN_BITS (KEY_LEAF_BITS + KEY_NODE_BITS)
+#define KR_WITHIN_MASK (((uint64_t) 1 << KR_WITHIN_BITS) - 1)
+#define KR_N (KEY_NODE_COUNT)
+#define KR_LEAVES (1u << KEY_NODE_BITS)
+#define KR_BATCH_MAX ((uint64_t) KR_N << KR_WITHIN_BITS)
+#define KR_NODES_SZ ((size_t) KR_N * SYMMKEYSZ)
+#define KR_TCACHE_WAYS 16 /* per-thread cache slots per direction (pow2) */
+#define KR_EPOCHS 16 /* 4-bit wire epoch: gens before wrap */
+
+#define KR_RP_WORDS (KEY_REPLAY_WINDOW / 64) /* pow2; RFC 6479 bitmap */
+#define KR_RP_SHIFT 6
+#define KR_RP_MASK 63
+#define KR_RP_WINDOW (KEY_REPLAY_WINDOW - 64) /* reserve 1 slack word */
+
+static const char kr_node_label[] = "o7s-keyrot-node";
+static const char kr_leaf_label[] = "o7s-keyrot-leaf";
+
+struct kr_batch {
+ uint64_t id; /* process-global, unique; cache key (no ABA) */
+ uint8_t epoch; /* 4-bit wire selector */
+ uint8_t * nodes; /* KR_NODES_SZ in secure heap; NULL if empty */
+ uint64_t tx_ctr; /* atomic; per-batch so nonces never collide */
+
+ struct { /* RFC 6479-like anti-replay window */
+ uint64_t last; /* highest accepted ctr + 1 */
+ uint64_t bits[KR_RP_WORDS];
+ pthread_mutex_t mtx;
+ } rp;
+};
+
+struct kr_keycache {
+ uint8_t * key; /* SYMMKEYSZ, points into the per-thread slab */
+ uint64_t id; /* batch the cached key belongs to */
+ uint16_t node;
+ uint8_t leaf;
+ uint8_t dir;
+ bool valid;
+};
+
+struct keyrot {
+ struct kr_batch * cur; /* published; read on data path */
+ struct kr_batch * prev; /* NULL = none */
+ struct rcu_guard guard; /* re-key vs readers */
+ uint8_t role;
+ uint8_t tx_epoch; /* epoch TX currently stamps */
+ bool peer_switched; /* peer is on the cur epoch */
+};
+
+/* Per-thread leaf-key caches, freed by the thread-exit destructor. */
+struct kr_tcache {
+ struct kr_keycache tx[KR_TCACHE_WAYS];
+ struct kr_keycache rx[KR_TCACHE_WAYS];
+ uint8_t * slab; /* 2*KR_TCACHE_WAYS*SYMMKEYSZ secure heap */
+};
+
+static struct {
+ uint64_t next_id; /* batch-id allocator (atomic) */
+ pthread_key_t tcache_key; /* per-thread leaf-key caches */
+ pthread_once_t tcache_once;
+} kr_g = { 0, 0, PTHREAD_ONCE_INIT };
+
+static void kr_tcache_free(void * p)
+{
+ struct kr_tcache * t = p;
+
+ if (t == NULL)
+ return;
+
+ crypt_secure_free(t->slab, 2 * KR_TCACHE_WAYS * SYMMKEYSZ);
+ free(t);
+}
+
+static void kr_tcache_init(void)
+{
+ pthread_key_create(&kr_g.tcache_key, kr_tcache_free);
+}
+
+static struct kr_tcache * kr_tcache_get(void)
+{
+ struct kr_tcache * t;
+ size_t i;
+
+ pthread_once(&kr_g.tcache_once, kr_tcache_init);
+
+ t = pthread_getspecific(kr_g.tcache_key);
+ if (t != NULL)
+ return t;
+
+ t = malloc(sizeof(*t));
+ if (t == NULL)
+ goto fail_alloc;
+
+ memset(t, 0, sizeof(*t));
+
+ t->slab = crypt_secure_malloc(2 * KR_TCACHE_WAYS * SYMMKEYSZ);
+ if (t->slab == NULL)
+ goto fail_slab;
+
+ for (i = 0; i < KR_TCACHE_WAYS; i++) {
+ t->tx[i].key = t->slab + i * SYMMKEYSZ;
+ t->rx[i].key = t->slab + (KR_TCACHE_WAYS + i) * SYMMKEYSZ;
+ }
+
+ if (pthread_setspecific(kr_g.tcache_key, t) != 0)
+ goto fail_set;
+
+ return t;
+
+ fail_set:
+ crypt_secure_free(t->slab, 2 * KR_TCACHE_WAYS * SYMMKEYSZ);
+ fail_slab:
+ free(t);
+ fail_alloc:
+ return NULL;
+}
+
+static uint8_t * kr_expand_nodes(const uint8_t * root)
+{
+ uint8_t * nodes;
+ buffer_t prk;
+ buffer_t info;
+ buffer_t okm;
+
+ nodes = crypt_secure_malloc(KR_NODES_SZ);
+ if (nodes == NULL)
+ return NULL;
+
+ prk.len = SYMMKEYSZ;
+ prk.data = (uint8_t *) root;
+ info.len = sizeof(kr_node_label) - 1;
+ info.data = (uint8_t *) kr_node_label;
+ okm.len = KR_NODES_SZ;
+ okm.data = nodes;
+
+ if (crypt_hkdf_expand(prk, info, okm) != 0)
+ goto fail_expand;
+
+ return nodes;
+
+ fail_expand:
+ crypt_secure_free(nodes, KR_NODES_SZ);
+ return NULL;
+}
+
+static int kr_leaf_key(const uint8_t * node,
+ uint8_t leaf,
+ uint8_t dir,
+ uint8_t * out)
+{
+ uint8_t info_buf[sizeof(kr_leaf_label) - 1 + 2];
+ buffer_t prk;
+ buffer_t info;
+ buffer_t okm;
+ size_t n = sizeof(kr_leaf_label) - 1;
+
+ memcpy(info_buf, kr_leaf_label, n);
+ info_buf[n] = dir;
+ info_buf[n + 1] = leaf;
+
+ prk.len = SYMMKEYSZ;
+ prk.data = (uint8_t *) node;
+ info.len = n + 2;
+ info.data = info_buf;
+ okm.len = SYMMKEYSZ;
+ okm.data = out;
+
+ return crypt_hkdf_expand(prk, info, okm);
+}
+
+static __inline__ bool kr_kc_hit(const struct kr_keycache * kc,
+ const struct kr_batch * b,
+ uint16_t node,
+ uint8_t leaf,
+ uint8_t dir)
+{
+ if (!kc->valid)
+ return false;
+
+ if (kc->id != b->id)
+ return false;
+
+ if (kc->node != node)
+ return false;
+
+ if (kc->leaf != leaf)
+ return false;
+
+ return kc->dir == dir;
+}
+
+/* Fetch the leaf key; derive into the (direct-mapped) slot on a miss. */
+static const uint8_t * kr_kc_get(struct kr_keycache * cache,
+ const struct kr_batch * b,
+ uint16_t node,
+ uint8_t leaf,
+ uint8_t dir)
+{
+ struct kr_keycache * kc;
+ uint8_t * nkey;
+
+ kc = &cache[b->id & (KR_TCACHE_WAYS - 1)];
+
+ if (kr_kc_hit(kc, b, node, leaf, dir))
+ return kc->key;
+
+ nkey = b->nodes + (size_t) node * SYMMKEYSZ;
+ if (kr_leaf_key(nkey, leaf, dir, kc->key) != 0)
+ return NULL;
+
+ kc->valid = true;
+ kc->id = b->id;
+ kc->node = node;
+ kc->leaf = leaf;
+ kc->dir = dir;
+
+ return kc->key;
+}
+
+static void kr_sel_enc(uint8_t epoch,
+ uint16_t node,
+ uint32_t seq,
+ uint8_t sel[KR_SELECTOR_LEN])
+{
+ sel[0] = (uint8_t) ((epoch << 4) | ((node >> 8) & 0x0F));
+ sel[1] = (uint8_t) (node & 0xFF);
+ sel[2] = (uint8_t) (seq >> 24);
+ sel[3] = (uint8_t) (seq >> 16);
+ sel[4] = (uint8_t) (seq >> 8);
+ sel[5] = (uint8_t) (seq);
+}
+
+static void kr_sel_dec(const uint8_t sel[KR_SELECTOR_LEN],
+ uint8_t * epoch,
+ uint16_t * node,
+ uint32_t * seq)
+{
+ *epoch = (uint8_t) (sel[0] >> 4);
+ *node = (uint16_t) (((sel[0] & 0x0F) << 8) | sel[1]);
+ *seq = ((uint32_t) sel[2] << 24) | ((uint32_t) sel[3] << 16) |
+ ((uint32_t) sel[4] << 8) | (uint32_t) sel[5];
+}
+
+static uint64_t kr_ctr(uint16_t node,
+ uint32_t seq)
+{
+ return ((uint64_t) node << KR_WITHIN_BITS) |
+ ((uint64_t) seq & KR_WITHIN_MASK);
+}
+
+static void kr_nonce(uint64_t ctr,
+ uint8_t * nonce)
+{
+ size_t i;
+
+ memset(nonce, 0, KR_NONCE_LEN);
+
+ /* ctr big-endian in the low 8 bytes; high bytes stay zero */
+ for (i = 0; i < 8; i++)
+ nonce[i] = (uint8_t) (ctr >> (56 - 8 * i));
+}
+
+static struct kr_batch * kr_batch_create(uint8_t epoch,
+ const uint8_t * root)
+{
+ struct kr_batch * b;
+
+ b = malloc(sizeof(*b));
+ if (b == NULL)
+ goto fail_alloc;
+
+ b->nodes = kr_expand_nodes(root);
+ if (b->nodes == NULL)
+ goto fail_nodes;
+
+ b->id = FETCH_ADD_RELAXED(&kr_g.next_id, 1);
+ b->epoch = epoch;
+ b->tx_ctr = 0;
+ if (pthread_mutex_init(&b->rp.mtx, NULL) != 0)
+ goto fail_lock;
+
+ b->rp.last = 0;
+ memset(b->rp.bits, 0, sizeof(b->rp.bits));
+
+ return b;
+
+ fail_lock:
+ crypt_secure_free(b->nodes, KR_NODES_SZ);
+ free(b);
+ return NULL;
+ fail_nodes:
+ free(b);
+ fail_alloc:
+ return NULL;
+}
+
+static void kr_batch_free(struct kr_batch * b)
+{
+ if (b == NULL)
+ return;
+
+ pthread_mutex_destroy(&b->rp.mtx);
+ crypt_secure_free(b->nodes, KR_NODES_SZ);
+ free(b);
+}
+
+/*
+ * RFC 6479 anti-replay window keyed on the per-batch counter, with
+ * seq = ctr + 1 so 0 means "nothing accepted yet". Returns 0 if the
+ * packet is fresh (and records it), -1 on a replay or a too-old ctr.
+ */
+static int kr_rp_commit(struct kr_batch * b,
+ uint64_t ctr)
+{
+ uint64_t seq;
+ uint64_t idx;
+ uint64_t cur;
+ uint64_t diff;
+
+ seq = ctr + 1;
+
+ pthread_mutex_lock(&b->rp.mtx);
+
+ if (seq > b->rp.last) {
+ idx = seq >> KR_RP_SHIFT;
+ cur = b->rp.last >> KR_RP_SHIFT;
+ diff = idx - cur;
+ if (diff > KR_RP_WORDS)
+ diff = KR_RP_WORDS;
+
+ while (diff-- > 0) {
+ cur++;
+ b->rp.bits[cur & (KR_RP_WORDS - 1)] = 0;
+ }
+
+ b->rp.bits[idx & (KR_RP_WORDS - 1)] |=
+ (uint64_t) 1 << (seq & KR_RP_MASK);
+ b->rp.last = seq;
+ goto finish;
+ }
+
+ if (b->rp.last - seq >= KR_RP_WINDOW)
+ goto fail;
+
+ idx = seq >> KR_RP_SHIFT;
+ if (b->rp.bits[idx & (KR_RP_WORDS - 1)]
+ & ((uint64_t) 1 << (seq & KR_RP_MASK)))
+ goto fail;
+
+ b->rp.bits[idx & (KR_RP_WORDS - 1)] |=
+ (uint64_t) 1 << (seq & KR_RP_MASK);
+ finish:
+ pthread_mutex_unlock(&b->rp.mtx);
+
+ return 0;
+ fail:
+ pthread_mutex_unlock(&b->rp.mtx);
+
+ return -1;
+}
+
+struct keyrot * keyrot_create(const uint8_t * root,
+ uint8_t epoch,
+ uint8_t role)
+{
+ struct keyrot * kr;
+
+ assert(root != NULL);
+ assert(role <= 1);
+
+ if (epoch >= KR_EPOCHS)
+ goto fail_kr;
+
+ kr = malloc(sizeof(*kr));
+ if (kr == NULL)
+ goto fail_kr;
+
+ memset(kr, 0, sizeof(*kr));
+
+ kr->role = role;
+ kr->tx_epoch = epoch;
+ kr->peer_switched = true;
+ kr->prev = NULL;
+
+ kr->cur = kr_batch_create(epoch, root);
+ if (kr->cur == NULL)
+ goto fail_cur;
+
+ if (rcu_guard_init(&kr->guard))
+ goto fail_guard;
+
+ return kr;
+
+ fail_guard:
+ kr_batch_free(kr->cur);
+ fail_cur:
+ free(kr);
+ fail_kr:
+ return NULL;
+}
+
+void keyrot_destroy(struct keyrot * kr)
+{
+ if (kr == NULL)
+ return;
+
+ /* Wait out any in-flight reader before freeing batches. */
+ rcu_drain(&kr->guard);
+
+ kr_batch_free(kr->cur);
+ kr_batch_free(kr->prev);
+
+ rcu_guard_fini(&kr->guard);
+
+ free(kr);
+}
+
+int keyrot_rekey(struct keyrot * kr,
+ const uint8_t * root,
+ uint8_t epoch)
+{
+ struct kr_batch * nb;
+ struct kr_batch * old_prev;
+
+ assert(kr != NULL);
+ assert(root != NULL);
+
+ if (epoch >= KR_EPOCHS)
+ return -1;
+
+ nb = kr_batch_create(epoch, root);
+ if (nb == NULL)
+ return -1;
+
+ rcu_wrlock(&kr->guard);
+
+ old_prev = kr->prev;
+ rcu_assign(kr->prev, kr->cur);
+ rcu_publish(nb);
+ rcu_assign(kr->cur, nb);
+
+ /* TX keeps the old epoch until the peer is seen on the new one. */
+ STORE_RELEASE(&kr->peer_switched, false);
+
+ rcu_wrunlock(&kr->guard);
+
+ /* old_prev is unreachable now; reclaim past any live reader. */
+ rcu_reclaim(&kr->guard);
+ kr_batch_free(old_prev);
+
+ return 0;
+}
+
+void keyrot_tx_promote(struct keyrot * kr)
+{
+ assert(kr != NULL);
+
+ /* Serialise with keyrot_rekey so tx_epoch tracks a consistent cur. */
+ rcu_wrlock(&kr->guard);
+ STORE_RELAXED(&kr->tx_epoch, rcu_deref(kr->cur)->epoch);
+ rcu_wrunlock(&kr->guard);
+}
+
+int keyrot_tx_next(struct keyrot * kr,
+ uint8_t sel[KR_SELECTOR_LEN],
+ const uint8_t ** key,
+ uint8_t nonce[KR_NONCE_LEN])
+{
+ struct kr_tcache * tc;
+ struct kr_batch * cur;
+ struct kr_batch * prev;
+ struct kr_batch * b;
+ uint64_t ctr;
+ uint16_t node;
+ uint8_t leaf;
+ uint8_t txe;
+ uint8_t epoch;
+ uint32_t seq;
+ const uint8_t * k;
+
+ assert(kr != NULL);
+ assert(key != NULL);
+
+ tc = kr_tcache_get();
+ if (tc == NULL)
+ return -1;
+
+ rcu_rdlock(&kr->guard);
+
+ cur = rcu_deref(kr->cur);
+ prev = rcu_deref(kr->prev);
+ rcu_consume(cur);
+ rcu_consume(prev);
+ txe = LOAD_RELAXED(&kr->tx_epoch);
+
+ if (cur->epoch == txe)
+ b = cur;
+ else if (prev != NULL && prev->epoch == txe)
+ b = prev;
+ else
+ b = NULL;
+
+ if (b == NULL) {
+ rcu_rdunlock(&kr->guard);
+ return -1; /* tx_epoch batch gone; next promote resyncs */
+ }
+
+ /* Slot reserved even if exhausted; tx_nodes_left clamps the count. */
+ ctr = FETCH_ADD_RELAXED(&b->tx_ctr, 1);
+ if (ctr >= KR_BATCH_MAX) {
+ rcu_rdunlock(&kr->guard);
+ return -1; /* batch exhausted */
+ }
+
+ node = (uint16_t) (ctr >> KR_WITHIN_BITS);
+ leaf = (uint8_t) ((ctr >> KEY_LEAF_BITS) & (KR_LEAVES - 1));
+ seq = (uint32_t) (ctr & KR_WITHIN_MASK);
+ epoch = b->epoch;
+
+ k = kr_kc_get(tc->tx, b, node, leaf, kr->role);
+
+ rcu_rdunlock(&kr->guard);
+
+ if (k == NULL)
+ return -1;
+
+ kr_sel_enc(epoch, node, seq, sel);
+ kr_nonce(ctr, nonce);
+
+ *key = k;
+
+ return 0;
+}
+
+int keyrot_rx_lookup(struct keyrot * kr,
+ const uint8_t sel[KR_SELECTOR_LEN],
+ const uint8_t ** key,
+ uint8_t nonce[KR_NONCE_LEN],
+ struct kr_rx * rx)
+{
+ struct kr_tcache * tc;
+ struct kr_batch * cur;
+ struct kr_batch * prev;
+ struct kr_batch * b;
+ uint8_t epoch;
+ uint16_t node;
+ uint32_t seq;
+ uint64_t ctr;
+ uint8_t leaf;
+ const uint8_t * k;
+
+ assert(kr != NULL);
+ assert(key != NULL);
+
+ kr_sel_dec(sel, &epoch, &node, &seq);
+
+ if (node >= KR_N)
+ return -1;
+
+ tc = kr_tcache_get();
+ if (tc == NULL)
+ return -1;
+
+ rcu_rdlock(&kr->guard);
+
+ cur = rcu_deref(kr->cur);
+ prev = rcu_deref(kr->prev);
+ rcu_consume(cur);
+ rcu_consume(prev);
+
+ if (epoch == cur->epoch) {
+ b = cur;
+ } else if (prev != NULL && epoch == prev->epoch) {
+ b = prev;
+ } else {
+ rcu_rdunlock(&kr->guard);
+ return -1; /* unknown epoch */
+ }
+
+ ctr = kr_ctr(node, seq);
+ leaf = (uint8_t) ((ctr >> KEY_LEAF_BITS) & (KR_LEAVES - 1));
+
+ /* peer's tx direction */
+ k = kr_kc_get(tc->rx, b, node, leaf, (uint8_t) (kr->role ^ 1));
+
+ rx->id = b->id;
+ rx->ctr = ctr;
+
+ rcu_rdunlock(&kr->guard);
+
+ if (k == NULL)
+ return -1;
+
+ kr_nonce(ctr, nonce);
+
+ *key = k;
+
+ return 0;
+}
+
+/*
+ * Commit a packet that authenticated under the batch keyrot_rx_lookup
+ * selected. Re-finds that batch by id (epoch may have advanced) and,
+ * if still resident, advances the replay window and records that the
+ * peer is on the current batch. Runs only post-AEAD so a forged or
+ * replayed packet can mutate no receiver state. Returns -1 on replay.
+ */
+int keyrot_rx_commit(struct keyrot * kr,
+ const struct kr_rx * rx)
+{
+ struct kr_batch * cur;
+ struct kr_batch * prev;
+ struct kr_batch * b;
+ int rc;
+
+ assert(kr != NULL);
+ assert(rx != NULL);
+
+ rcu_rdlock(&kr->guard);
+
+ cur = rcu_deref(kr->cur);
+ prev = rcu_deref(kr->prev);
+ rcu_consume(cur);
+ rcu_consume(prev);
+
+ if (cur->id == rx->id)
+ b = cur;
+ else if (prev != NULL && prev->id == rx->id)
+ b = prev;
+ else
+ b = NULL;
+
+ if (b == NULL) {
+ rcu_rdunlock(&kr->guard);
+ return 0; /* batch evicted post-auth; nothing to protect */
+ }
+
+ rc = kr_rp_commit(b, rx->ctr);
+ if (rc == 0 && b == cur)
+ STORE_RELEASE(&kr->peer_switched, true);
+
+ rcu_rdunlock(&kr->guard);
+
+ return rc;
+}
+
+bool keyrot_peer_switched(const struct keyrot * kr)
+{
+ assert(kr != NULL);
+
+ return LOAD_ACQUIRE(&kr->peer_switched);
+}
+
+unsigned keyrot_tx_nodes_left(struct keyrot * kr)
+{
+ struct kr_batch * cur;
+ struct kr_batch * prev;
+ struct kr_batch * b;
+ uint64_t ctr;
+ unsigned used;
+ uint8_t txe;
+
+ assert(kr != NULL);
+
+ rcu_rdlock(&kr->guard);
+ cur = rcu_deref(kr->cur);
+ prev = rcu_deref(kr->prev);
+ rcu_consume(cur);
+ rcu_consume(prev);
+ txe = LOAD_RELAXED(&kr->tx_epoch);
+
+ if (cur->epoch == txe)
+ b = cur;
+ else if (prev != NULL && prev->epoch == txe)
+ b = prev;
+ else
+ b = NULL;
+
+ ctr = b != NULL ? LOAD_RELAXED(&b->tx_ctr) : KR_BATCH_MAX;
+ rcu_rdunlock(&kr->guard);
+
+ used = (unsigned) (ctr >> KR_WITHIN_BITS);
+ if (used >= KR_N)
+ return 0;
+
+ return KR_N - used;
+}
generated by cgit v1.2.3 (git 2.39.1) at 2026-07-01 21:40:06 +0000