/**
 * Utility functions for URL building, header manipulation, and query string handling
 */
import { URL } from "url";
import { ProxyLogger } from "./logger";
/**
 * Builds a URL from source and optional base with security validation
 */
export declare function buildURL(source: string, base?: string, logger?: ProxyLogger, requestId?: string, req?: Request): URL;
/**
 * Filters out a specific header (case-insensitive)
 */
export declare function filterHeaders(headers: Record<string, string>, filter: string): Record<string, string>;
/**
 * Converts Headers object to plain object
 */
export declare function headersToRecord(headers: Headers): Record<string, string>;
/**
 * Converts plain object to Headers object with security validation
 */
export declare function recordToHeaders(record: Record<string, string>, logger?: ProxyLogger, requestId?: string, req?: Request): Headers;
/**
 * Builds query string from parameters with security validation
 */
export declare function buildQueryString(params: Record<string, any> | string, logger?: ProxyLogger, requestId?: string, req?: Request): string;
/**
 * Validates HTTP method for security issues
 */
export declare function validateHttpMethod(method: string, logger?: ProxyLogger, requestId?: string, req?: Request): void;
/**
 * Securely normalizes a path by removing directory traversal sequences and ensuring it stays within allowed bounds
 * @param inputPath - The input path that may contain traversal sequences
 * @param allowedPrefix - The prefix that the normalized path must start with (e.g., "/files/")
 * @returns The normalized path that is safe from directory traversal
 * @throws Error if the path attempts to escape the allowed prefix
 */
export declare function normalizeSecurePath(inputPath: string, allowedPrefix: string): string;
/**
 * Security configuration constants for DoS prevention
 */
export declare const SECURITY_LIMITS: {
    readonly MAX_ITERATIONS: 1000;
    readonly MAX_CONCURRENCY: 50;
    readonly MAX_FILE_SIZE: number;
    readonly MAX_STRING_LENGTH: 1000;
    readonly MAX_TIMEOUT: 60000;
    readonly MAX_QUERY_PARAMS: 100;
    readonly MAX_HEADERS: 50;
    readonly MAX_URL_LENGTH: 2048;
};
/**
 * Validates and limits numeric parameters to prevent DoS attacks
 * @param value - The numeric value to validate
 * @param max - Maximum allowed value
 * @param paramName - Name of the parameter for error messages
 * @returns The validated and limited value
 */
export declare function validateNumericLimit(value: number, max: number, paramName: string): number;
/**
 * Validates string length to prevent memory exhaustion attacks
 * @param value - The string to validate
 * @param maxLength - Maximum allowed length
 * @param paramName - Name of the parameter for error messages
 * @returns The validated string
 */
export declare function validateStringLength(value: string, maxLength: number, paramName: string): string;
/**
 * Validates file size to prevent resource exhaustion
 * @param size - The file size in bytes
 * @param maxSize - Maximum allowed size in bytes
 * @returns The validated size
 */
export declare function validateFileSize(size: number, maxSize?: number): number;
/**
 * Validates URL length to prevent memory exhaustion
 * @param url - The URL string to validate
 * @returns The validated URL string
 */
export declare function validateUrlLength(url: string): string;
/**
 * Creates a rate limiter function to prevent DoS attacks
 * @param maxRequests - Maximum requests allowed per window
 * @param windowMs - Time window in milliseconds
 * @returns Rate limiter function
 */
export declare function createRateLimiter(maxRequests: number, windowMs: number): (identifier: string) => boolean;
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