Avoid using the same handshake key to establish more than one session

This fix prevents a potential attack using intentional packet reordering to
initialize more than one session with using the same handshake keys, leading
to more that one session to be initialized with the same key data altogether,
allowing to decrypt some packets in the worst case.

1 files changed, 3 insertions, 1 deletions

diff --git a/src/fastd.h b/src/fastd.h
index 8a0fcce..ff7cab9 100644
--- a/src/fastd.h
+++ b/src/fastd.h
@@ -73,6 +73,8 @@ struct _fastd_protocol {
 	void (*handle_recv)(fastd_context *ctx, fastd_peer *peer, fastd_buffer buffer);
 	void (*send)(fastd_context *ctx, fastd_peer *peer, fastd_buffer buffer);
 
+	void (*init_peer_state)(fastd_context *ctx, fastd_peer *peer);
+	void (*reset_peer_state)(fastd_context *ctx, fastd_peer *peer);
 	void (*free_peer_state)(fastd_context *ctx, fastd_peer *peer);
 
 	void (*generate_key)(fastd_context *ctx);
@@ -86,7 +88,7 @@ struct _fastd_method {
 	size_t (*min_encrypt_head_space)(fastd_context *ctx);
 	size_t (*min_decrypt_head_space)(fastd_context *ctx);
 
-	fastd_method_session_state* (*session_init)(fastd_context *ctx, uint8_t *secret, size_t length, bool initiator, fastd_method_session_state *prev_session);
+	fastd_method_session_state* (*session_init)(fastd_context *ctx, uint8_t *secret, size_t length, bool initiator);
 	bool (*session_is_valid)(fastd_context *ctx, fastd_method_session_state *session);
 	bool (*session_is_initiator)(fastd_context *ctx, fastd_method_session_state *session);
 	bool (*session_want_refresh)(fastd_context *ctx, fastd_method_session_state *session);