rate_limit.h

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#pragma once
 
#include "../../asciichat_errno.h"
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>

typedef enum {
  // ACDS discovery server events
  RATE_EVENT_SESSION_CREATE = 0, 
  RATE_EVENT_SESSION_LOOKUP = 1, 
  RATE_EVENT_SESSION_JOIN = 2,   
 
  // ascii-chat server events
  RATE_EVENT_CONNECTION = 3,   
  RATE_EVENT_IMAGE_FRAME = 4,  
  RATE_EVENT_AUDIO = 5,        
  RATE_EVENT_PING = 6,         
  RATE_EVENT_CLIENT_JOIN = 7,  
  RATE_EVENT_CONTROL = 8,      
  RATE_EVENT_HTTP_REQUEST = 9, 
 
  RATE_EVENT_MAX 
} rate_event_type_t;

typedef struct {
  uint32_t max_events;  
  uint32_t window_secs; 
} rate_limit_config_t;

typedef struct rate_limiter_s rate_limiter_t;

typedef struct {
  asciichat_error_t (*check)(void *backend_data, const char *ip_address, rate_event_type_t event_type,
                             const rate_limit_config_t *config, bool *allowed);
 
  asciichat_error_t (*record)(void *backend_data, const char *ip_address, rate_event_type_t event_type);
 
  asciichat_error_t (*cleanup)(void *backend_data, uint32_t max_age_secs);
 
  void (*destroy)(void *backend_data);
} rate_limiter_backend_ops_t;

extern const rate_limit_config_t DEFAULT_RATE_LIMITS[RATE_EVENT_MAX];
 
// ============================================================================
// Rate Limiter Creation
// ============================================================================

rate_limiter_t *rate_limiter_create_memory(void);

rate_limiter_t *rate_limiter_create_sqlite(const char *db_path);

void rate_limiter_set_sqlite_db(rate_limiter_t *limiter, void *db);

void rate_limiter_destroy(rate_limiter_t *limiter);
 
// ============================================================================
// Rate Limiting Operations
// ============================================================================

asciichat_error_t rate_limiter_check(rate_limiter_t *limiter, const char *ip_address, rate_event_type_t event_type,
                                     const rate_limit_config_t *config, bool *allowed);

asciichat_error_t rate_limiter_record(rate_limiter_t *limiter, const char *ip_address, rate_event_type_t event_type);

asciichat_error_t rate_limiter_prune(rate_limiter_t *limiter, uint32_t max_age_secs);
 
// ============================================================================
// Utility Functions
// ============================================================================

const char *rate_limiter_event_type_string(rate_event_type_t event_type);