v0.7.7 - Prevent sql attacks and rate limiting on subscriptions

src/websockets.h

@@ -14,7 +14,7 @@
 #define CHALLENGE_MAX_LENGTH 128
 #define AUTHENTICATED_PUBKEY_MAX_LENGTH 65  // 64 hex + null
 
-// Enhanced per-session data with subscription management and NIP-42 authentication
+// Enhanced per-session data with subscription management, NIP-42 authentication, and rate limiting
 struct per_session_data {
     int authenticated;
     struct subscription* subscriptions;      // Head of this session's subscription list
@@ -30,6 +30,12 @@ struct per_session_data {
     int nip42_auth_required_events;          // Whether NIP-42 auth is required for EVENT submission
     int nip42_auth_required_subscriptions;   // Whether NIP-42 auth is required for REQ operations
     int auth_challenge_sent;                 // Whether challenge has been sent (0/1)
+
+    // Rate limiting for subscription attempts
+    int failed_subscription_attempts;        // Count of failed subscription attempts
+    time_t last_failed_attempt;              // Timestamp of last failed attempt
+    time_t rate_limit_until;                 // Time until rate limiting expires
+    int consecutive_failures;                // Consecutive failed attempts for backoff
 };
 
 // NIP-11 HTTP session data structure for managing buffer lifetime