interface RateLimitBucket {
timestamps: number[];
}
export class RateLimiter {
private buckets = new Map<string, RateLimitBucket>();
private globalBucket: RateLimitBucket = { timestamps: [] };
private globalMaxRequests: number;
private globalWindowMs: number;
private toolLimits = new Map<string, { maxRequests: number; windowMs: number }>();
constructor(
globalMaxRequests = 100,
globalWindowMs = 60_000
) {
this.globalMaxRequests = globalMaxRequests;
this.globalWindowMs = globalWindowMs;
// Stricter limits for destructive operations
const destructiveLimits = { maxRequests: 5, windowMs: 60_000 };
const mutateLimits = { maxRequests: 10, windowMs: 60_000 };
for (const tool of ["dns_delete_zone", "dns_delete_record", "dns_flush_cache"]) {
this.toolLimits.set(tool, destructiveLimits);
}
for (const tool of [
"dns_create_zone", "dns_add_record", "dns_update_record",
"dns_block_domain", "dns_allow_domain",
]) {
this.toolLimits.set(tool, mutateLimits);
}
}
check(toolName: string): { allowed: boolean; retryAfterMs?: number } {
const now = Date.now();
// Check global limit
this.pruneTimestamps(this.globalBucket, now, this.globalWindowMs);
if (this.globalBucket.timestamps.length >= this.globalMaxRequests) {
const oldest = this.globalBucket.timestamps[0];
return {
allowed: false,
retryAfterMs: oldest + this.globalWindowMs - now,
};
}
// Check per-tool limit
const limit = this.toolLimits.get(toolName);
if (limit) {
if (!this.buckets.has(toolName)) {
this.buckets.set(toolName, { timestamps: [] });
}
const bucket = this.buckets.get(toolName)!;
this.pruneTimestamps(bucket, now, limit.windowMs);
if (bucket.timestamps.length >= limit.maxRequests) {
const oldest = bucket.timestamps[0];
return {
allowed: false,
retryAfterMs: oldest + limit.windowMs - now,
};
}
bucket.timestamps.push(now);
}
this.globalBucket.timestamps.push(now);
return { allowed: true };
}
private pruneTimestamps(
bucket: RateLimitBucket,
now: number,
windowMs: number
): void {
const cutoff = now - windowMs;
while (bucket.timestamps.length > 0 && bucket.timestamps[0] < cutoff) {
bucket.timestamps.shift();
}
}
}
