generalbots/botbook/src/09-security/system-limits.md

System Limits & Rate Limiting

General Bots enforces strict system limits to ensure fair resource usage, prevent abuse, and maintain platform stability for all users.

Overview

All limits are defined in botlib/src/limits.rs and enforced throughout the platform. When limits are exceeded, the system returns HTTP 429 (Too Many Requests) with appropriate Retry-After headers.

Resource Limits

Loop & Recursion Protection

Limit	Value	Purpose
MAX_LOOP_ITERATIONS	100,000	Prevents infinite loops in BASIC scripts
MAX_RECURSION_DEPTH	100	Prevents stack overflow from deep recursion
MAX_SCRIPT_EXECUTION_SECONDS	300	Maximum script runtime (5 minutes)

File & Data Limits

Limit	Value	Purpose
MAX_FILE_SIZE_BYTES	100 MB	Maximum file size for processing
MAX_UPLOAD_SIZE_BYTES	50 MB	Maximum upload size per request
MAX_REQUEST_BODY_BYTES	10 MB	Maximum HTTP request body
MAX_STRING_LENGTH	10 MB	Maximum string length in scripts
MAX_ARRAY_LENGTH	1,000,000	Maximum array elements

Connection Limits

Limit	Value	Purpose
MAX_CONCURRENT_REQUESTS_PER_USER	100	Per-user concurrent request limit
MAX_CONCURRENT_REQUESTS_GLOBAL	10,000	Platform-wide concurrent limit
MAX_WEBSOCKET_CONNECTIONS_PER_USER	10	WebSocket connections per user
MAX_WEBSOCKET_CONNECTIONS_GLOBAL	50,000	Platform-wide WebSocket limit
MAX_DB_CONNECTIONS_PER_TENANT	20	Database connections per tenant

API Rate Limits

Limit	Value	Purpose
MAX_API_CALLS_PER_MINUTE	1,000	Requests per user per minute
MAX_API_CALLS_PER_HOUR	10,000	Requests per user per hour
MAX_LLM_REQUESTS_PER_MINUTE	60	LLM API calls per minute

LLM & Knowledge Base Limits

Limit	Value	Purpose
MAX_LLM_TOKENS_PER_REQUEST	128,000	Maximum tokens per LLM request
MAX_KB_DOCUMENTS_PER_BOT	100,000	Documents per bot knowledge base
MAX_KB_DOCUMENT_SIZE_BYTES	50 MB	Maximum document size for KB
MAX_DB_QUERY_RESULTS	10,000	Maximum query result rows

Tenant & Resource Limits

Limit	Value	Purpose
MAX_DRIVE_STORAGE_BYTES	10 GB	Storage per tenant
MAX_SESSIONS_PER_USER	10	Concurrent sessions per user
MAX_SESSION_IDLE_SECONDS	3,600	Session timeout (1 hour)
MAX_BOTS_PER_TENANT	100	Bots per tenant
MAX_TOOLS_PER_BOT	500	Tools per bot
MAX_PENDING_TASKS	1,000	Pending automation tasks

Rate Limiting Implementation

Using the Rate Limiter

use botlib::{RateLimiter, SystemLimits, format_limit_error_response};

let rate_limiter = RateLimiter::new(SystemLimits::default());

async fn handle_request(user_id: &str) -> Response {
    if let Err(limit_error) = rate_limiter.check_rate_limit(user_id).await {
        let (status, body) = format_limit_error_response(&limit_error);
        return (StatusCode::TOO_MANY_REQUESTS, body);
    }
    
    // Process request...
}

Checking Loop Limits in Scripts

use botlib::{check_loop_limit, MAX_LOOP_ITERATIONS};

let mut iterations = 0;
loop {
    check_loop_limit(iterations, MAX_LOOP_ITERATIONS)?;
    iterations += 1;
    
    // Loop body...
    
    if done {
        break;
    }
}

Response Format

When a limit is exceeded, the API returns:

{
    "error": "rate_limit_exceeded",
    "message": "Limit exceeded for api_calls_minute: 1001 > 1000 (max)",
    "limit_type": "api_calls_minute",
    "current": 1001,
    "maximum": 1000,
    "retry_after_secs": 60
}

HTTP Headers:

• Status: 429 Too Many Requests
• Retry-After: 60
• X-RateLimit-Limit: 1000
• X-RateLimit-Remaining: 0
• X-RateLimit-Reset: 1234567890

BASIC Script Limits

Scripts written in .gbdialog files are automatically protected:

' This loop is safe - system enforces MAX_LOOP_ITERATIONS
WHILE condition
    ' Loop body
WEND

' FOR loops are also protected
FOR i = 1 TO 1000000
    ' Will stop at MAX_LOOP_ITERATIONS
NEXT

If a script exceeds limits:

• Loop iterations: Script terminates with "Maximum iterations exceeded" error
• Execution time: Script terminates after MAX_SCRIPT_EXECUTION_SECONDS
• Memory/string size: Script terminates with "Limit exceeded" error

Customizing Limits

Administrators can customize limits per tenant via environment variables or configuration:

[limits]
max_api_calls_per_minute = 2000
max_drive_storage_bytes = 21474836480  # 20 GB
max_bots_per_tenant = 200

Best Practices

For Bot Developers

1. Avoid unbounded loops - Always include exit conditions
2. Paginate queries - Don't fetch unlimited results
3. Cache responses - Reduce API calls with caching
4. Use webhooks - Instead of polling, use event-driven patterns
5. Batch operations - Combine multiple operations when possible

For System Administrators

1. Monitor rate limit hits - Track 429 responses in analytics
2. Set appropriate limits - Balance security with usability
3. Configure burst allowance - Use RATE_LIMIT_BURST_MULTIPLIER for temporary spikes
4. Clean up stale entries - Rate limiter auto-cleans after 2 hours

Error Handling

use botlib::{LimitExceeded, LimitType};

match result {
    Err(LimitExceeded { limit_type, current, maximum, retry_after_secs }) => {
        match limit_type {
            LimitType::ApiCallsMinute => {
                // Handle minute rate limit
            }
            LimitType::LoopIterations => {
                // Handle infinite loop detection
            }
            _ => {
                // Handle other limits
            }
        }
    }
    Ok(value) => {
        // Success
    }
}

Security Considerations

• DDoS Protection: Rate limits prevent resource exhaustion attacks
• Abuse Prevention: Per-user limits prevent single-user abuse
• Fair Usage: Ensures resources are shared fairly across all users
• Cost Control: LLM token limits prevent unexpected costs

See Also

• Security Features - Overall security architecture
• API Endpoints - API documentation
• Compliance Requirements - Regulatory compliance