1 files changed, 137 insertions, 0 deletions
diff --git a/src/hashtables.c b/src/hashtables.c
new file mode 100644
index 0000000..8911625
--- /dev/null
+++ b/src/hashtables.c
@@ -0,0 +1,137 @@
+/* Copyright 2015-2016 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved. */
+
+#include "wireguard.h"
+#include "hashtables.h"
+#include "peer.h"
+#include "crypto/siphash24.h"
+#include "noise.h"
+#include <linux/hashtable.h>
+
+static inline struct hlist_head *pubkey_bucket(struct pubkey_hashtable *table, const uint8_t pubkey[NOISE_PUBLIC_KEY_LEN])
+{
+	/* siphash24 gives us a secure 64bit number based on a random key. Since the bits are
+	 * uniformly distributed, we can then mask off to get the bits we need. */
+	return &table->hashtable[siphash24(pubkey, NOISE_PUBLIC_KEY_LEN, table->key) & (HASH_SIZE(table->hashtable) - 1)];
+}
+
+void pubkey_hashtable_init(struct pubkey_hashtable *table)
+{
+	get_random_bytes(table->key, SIPHASH24_KEY_LEN);
+	hash_init(table->hashtable);
+	mutex_init(&table->lock);
+}
+
+void pubkey_hashtable_add(struct pubkey_hashtable *table, struct wireguard_peer *peer)
+{
+	mutex_lock(&table->lock);
+	hlist_add_head_rcu(&peer->pubkey_hash, pubkey_bucket(table, peer->handshake.remote_static));
+	mutex_unlock(&table->lock);
+}
+
+void pubkey_hashtable_remove(struct pubkey_hashtable *table, struct wireguard_peer *peer)
+{
+	mutex_lock(&table->lock);
+	hlist_del_init_rcu(&peer->pubkey_hash);
+	mutex_unlock(&table->lock);
+}
+
+/* Returns a strong reference to a peer */
+struct wireguard_peer *pubkey_hashtable_lookup(struct pubkey_hashtable *table, const uint8_t pubkey[NOISE_PUBLIC_KEY_LEN])
+{
+	struct wireguard_peer *iter_peer, *peer = NULL;
+	rcu_read_lock();
+	hlist_for_each_entry_rcu(iter_peer, pubkey_bucket(table, pubkey), pubkey_hash) {
+		if (!memcmp(pubkey, iter_peer->handshake.remote_static, NOISE_PUBLIC_KEY_LEN)) {
+			peer = iter_peer;
+			break;
+		}
+	}
+	peer = peer_get(peer);
+	rcu_read_unlock();
+	return peer;
+}
+
+static inline struct hlist_head *index_bucket(struct index_hashtable *table, const __le32 index)
+{
+	/* Since the indices are random and thus all bits are uniformly distributed,
+	 * we can find its bucket simply by masking. */
+	return &table->hashtable[(__force u32)index & (HASH_SIZE(table->hashtable) - 1)];
+}
+
+void index_hashtable_init(struct index_hashtable *table)
+{
+	hash_init(table->hashtable);
+	spin_lock_init(&table->lock);
+}
+
+__le32 index_hashtable_insert(struct index_hashtable *table, struct index_hashtable_entry *entry)
+{
+	struct index_hashtable_entry *existing_entry;
+
+	spin_lock(&table->lock);
+	hlist_del_init_rcu(&entry->index_hash);
+	spin_unlock(&table->lock);
+
+	rcu_read_lock();
+
+search_unused_slot:
+	/* First we try to find an unused slot, randomly, while unlocked. */
+	get_random_bytes(&entry->index, sizeof(entry->index));
+	hlist_for_each_entry_rcu(existing_entry, index_bucket(table, entry->index), index_hash) {
+		if (existing_entry->index == entry->index)
+			goto search_unused_slot; /* If it's already in use, we continue searching. */
+	}
+
+	/* Once we've found an unused slot, we lock it, and then double-check
+	 * that nobody else stole it from us. */
+	spin_lock(&table->lock);
+	hlist_for_each_entry_rcu(existing_entry, index_bucket(table, entry->index), index_hash) {
+		if (existing_entry->index == entry->index) {
+			spin_unlock(&table->lock);
+			goto search_unused_slot; /* If it was stolen, we start over. */
+		}
+	}
+	/* Otherwise, we know we have it exclusively (since we're locked), so we insert. */
+	hlist_add_head_rcu(&entry->index_hash, index_bucket(table, entry->index));
+	spin_unlock(&table->lock);
+
+	rcu_read_unlock();
+
+	return entry->index;
+}
+
+void index_hashtable_replace(struct index_hashtable *table, struct index_hashtable_entry *old, struct index_hashtable_entry *new)
+{
+	spin_lock(&table->lock);
+	new->index = old->index;
+	hlist_replace_rcu(&old->index_hash, &new->index_hash);
+	INIT_HLIST_NODE(&old->index_hash);
+	spin_unlock(&table->lock);
+}
+
+void index_hashtable_remove(struct index_hashtable *table, struct index_hashtable_entry *entry)
+{
+	spin_lock(&table->lock);
+	hlist_del_init_rcu(&entry->index_hash);
+	spin_unlock(&table->lock);
+}
+
+/* Returns a strong reference to a entry->peer */
+struct index_hashtable_entry *index_hashtable_lookup(struct index_hashtable *table, const enum index_hashtable_type type_mask, const __le32 index)
+{
+	struct index_hashtable_entry *iter_entry, *entry = NULL;
+	rcu_read_lock();
+	hlist_for_each_entry_rcu(iter_entry, index_bucket(table, index), index_hash) {
+		if (iter_entry->index == index && (iter_entry->type & type_mask)) {
+			entry = iter_entry;
+			break;
+		}
+	}
+	if (likely(entry)) {
+		entry->peer = peer_get(entry->peer);
+		if (unlikely(!entry->peer))
+			entry = NULL;
+	}
+	rcu_read_unlock();
+	return entry;
+}