rate_limit.c

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#include <ascii-chat/network/rate_limit/rate_limit.h>
#include <ascii-chat/network/rate_limit/memory.h>
#include <ascii-chat/network/rate_limit/sqlite.h>
#include <ascii-chat/log/logging.h>
#include <ascii-chat/util/time.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
 
// Event type strings for logging
static const char *event_type_strings[RATE_EVENT_MAX] = {
    [RATE_EVENT_SESSION_CREATE] = "session_create",
    [RATE_EVENT_SESSION_LOOKUP] = "session_lookup",
    [RATE_EVENT_SESSION_JOIN] = "session_join",
    [RATE_EVENT_CONNECTION] = "connection",
    [RATE_EVENT_IMAGE_FRAME] = "image_frame",
    [RATE_EVENT_AUDIO] = "audio",
    [RATE_EVENT_PING] = "ping",
    [RATE_EVENT_CLIENT_JOIN] = "client_join",
    [RATE_EVENT_CONTROL] = "control",
};
 
// Default rate limits: conservative defaults to prevent abuse
// Debug builds have relaxed limits for development/testing
const rate_limit_config_t DEFAULT_RATE_LIMITS[RATE_EVENT_MAX] = {
// ACDS discovery server limits
#ifdef NDEBUG
    // Release mode: production limits (144 FPS video, 172 FPS audio)
    [RATE_EVENT_SESSION_CREATE] = {.max_events = 10, .window_secs = 60}, // 10 creates per minute
    [RATE_EVENT_SESSION_LOOKUP] = {.max_events = 30, .window_secs = 60}, // 30 lookups per minute
    [RATE_EVENT_SESSION_JOIN] = {.max_events = 20, .window_secs = 60},   // 20 joins per minute
    [RATE_EVENT_CONNECTION] = {.max_events = 50, .window_secs = 60},     // 50 connections per minute
    [RATE_EVENT_IMAGE_FRAME] = {.max_events = 8640, .window_secs = 60},  // 8640 frames/min = 144 FPS
    [RATE_EVENT_AUDIO] = {.max_events = 10320, .window_secs = 60},       // 10320 packets/min = 172 FPS
    [RATE_EVENT_PING] = {.max_events = 120, .window_secs = 60},          // 120 pings/min = 2 Hz max
    [RATE_EVENT_CLIENT_JOIN] = {.max_events = 10, .window_secs = 60},    // 10 joins per minute
    [RATE_EVENT_CONTROL] = {.max_events = 100, .window_secs = 60},       // 100 control packets/min
#else
    // Debug mode: slightly relaxed limits for development/testing (1.5x production limits)
    [RATE_EVENT_SESSION_CREATE] = {.max_events = 15, .window_secs = 60}, // 15 creates per minute
    [RATE_EVENT_SESSION_LOOKUP] = {.max_events = 45, .window_secs = 60}, // 45 lookups per minute
    [RATE_EVENT_SESSION_JOIN] = {.max_events = 30, .window_secs = 60},   // 30 joins per minute
    [RATE_EVENT_CONNECTION] = {.max_events = 75, .window_secs = 60},     // 75 connections per minute
    [RATE_EVENT_IMAGE_FRAME] = {.max_events = 12960, .window_secs = 60}, // 12960 frames/min = 216 FPS
    [RATE_EVENT_AUDIO] = {.max_events = 15480, .window_secs = 60},       // 15480 packets/min = 258 FPS
    [RATE_EVENT_PING] = {.max_events = 180, .window_secs = 60},          // 180 pings/min = 3 Hz
    [RATE_EVENT_CLIENT_JOIN] = {.max_events = 25, .window_secs = 60},    // 25 joins per minute (for testing reconnects)
    [RATE_EVENT_CONTROL] = {.max_events = 150, .window_secs = 60},       // 150 control packets/min
#endif
};
 
// ============================================================================
// Backend Interface
// ============================================================================
 
struct rate_limiter_s {
  const rate_limiter_backend_ops_t *ops; 
  void *backend_data;                    
};
 
// ============================================================================
// Public API Implementation
// ============================================================================
 
rate_limiter_t *rate_limiter_create_memory(void) {
  rate_limiter_t *limiter = malloc(sizeof(rate_limiter_t));
  if (!limiter) {
    log_error("Failed to allocate rate limiter");
    return NULL;
  }
 
  limiter->backend_data = memory_backend_create();
  if (!limiter->backend_data) {
    free(limiter);
    return NULL;
  }
 
  limiter->ops = &memory_backend_ops;
  return limiter;
}
 
rate_limiter_t *rate_limiter_create_sqlite(const char *db_path) {
  rate_limiter_t *limiter = malloc(sizeof(rate_limiter_t));
  if (!limiter) {
    log_error("Failed to allocate rate limiter");
    return NULL;
  }
 
  limiter->backend_data = sqlite_backend_create(db_path);
  if (!limiter->backend_data) {
    free(limiter);
    return NULL;
  }
 
  limiter->ops = &sqlite_backend_ops;
  return limiter;
}
 
void rate_limiter_set_sqlite_db(rate_limiter_t *limiter, void *db) {
  if (!limiter || !limiter->backend_data) {
    return;
  }
 
  // Call the SQLite backend function to set the database handle
  sqlite_backend_set_db(limiter->backend_data, (sqlite3 *)db);
}
 
void rate_limiter_destroy(rate_limiter_t *limiter) {
  if (!limiter) {
    return;
  }
 
  if (limiter->ops && limiter->ops->destroy) {
    limiter->ops->destroy(limiter->backend_data);
  }
 
  free(limiter);
}
 
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) {
  if (!limiter || !limiter->ops || !limiter->ops->check) {
    return SET_ERRNO(ERROR_INVALID_PARAM, "Invalid rate limiter");
  }
 
  if (!ip_address || !allowed) {
    return SET_ERRNO(ERROR_INVALID_PARAM, "ip_address or allowed is NULL");
  }
 
  if (event_type >= RATE_EVENT_MAX) {
    return SET_ERRNO(ERROR_INVALID_PARAM, "Invalid event_type: %d", event_type);
  }
 
  return limiter->ops->check(limiter->backend_data, ip_address, event_type, config, allowed);
}
 
asciichat_error_t rate_limiter_record(rate_limiter_t *limiter, const char *ip_address, rate_event_type_t event_type) {
  if (!limiter || !limiter->ops || !limiter->ops->record) {
    return SET_ERRNO(ERROR_INVALID_PARAM, "Invalid rate limiter");
  }
 
  if (!ip_address) {
    return SET_ERRNO(ERROR_INVALID_PARAM, "ip_address is NULL");
  }
 
  if (event_type >= RATE_EVENT_MAX) {
    return SET_ERRNO(ERROR_INVALID_PARAM, "Invalid event_type: %d", event_type);
  }
 
  return limiter->ops->record(limiter->backend_data, ip_address, event_type);
}
 
asciichat_error_t rate_limiter_prune(rate_limiter_t *limiter, uint32_t max_age_secs) {
  if (!limiter || !limiter->ops || !limiter->ops->cleanup) {
    return SET_ERRNO(ERROR_INVALID_PARAM, "Invalid rate limiter");
  }
 
  return limiter->ops->cleanup(limiter->backend_data, max_age_secs);
}
 
// ============================================================================
// Helper Functions (available to backends)
// ============================================================================
 
const char *rate_limiter_event_type_string(rate_event_type_t event_type) {
  if (event_type >= RATE_EVENT_MAX) {
    return "unknown";
  }
  return event_type_strings[event_type];
}