/**
 * wsServer.ts — a minimal RFC 6455 WebSocket server, hand-rolled.
 *
 * The package ships three runtime dependencies and adding `ws` for one loopback
 * socket is not worth it, so this implements exactly the slice the bridge
 * needs: the upgrade handshake, text frames, ping/pong and close. Binary frames
 * are accepted and dropped; no extensions or subprotocols are negotiated.
 *
 * It binds the loopback interface only — never 0.0.0.0 — and refuses any
 * upgrade carrying a browser Origin, which is the first half of the defence
 * against cross-site WebSocket hijacking (the token check in bridge.ts is the
 * other half, because a non-browser client can forge any header it likes).
 */
import { type IncomingMessage } from 'http';
export interface WsConnection {
    id: number;
    send(text: string): void;
    close(code?: number, reason?: string): void;
    readonly closed: boolean;
    /** Per-connection state the owner attaches (auth status, timers). */
    meta: Record<string, unknown>;
}
export interface WsServerHandlers {
    onConnection(conn: WsConnection, req: IncomingMessage): void;
    onMessage(conn: WsConnection, text: string): void;
    onClose(conn: WsConnection): void;
}
/**
 * An Origin header proves a browser made the request. The nwjs game page loads
 * from file:// and sends either no Origin or "null"/"file://", so any http(s)
 * origin is a web page reaching for us and is refused outright.
 */
export declare function originAllowed(origin: string | undefined): boolean;
export declare function acceptKey(key: string): string;
/** Encode one server-to-client frame (never masked, per the RFC). */
export declare function encodeFrame(payload: Buffer, opcode?: number): Buffer;
export interface DecodedFrame {
    fin: boolean;
    opcode: number;
    payload: Buffer;
    /** Total bytes consumed from the input buffer. */
    size: number;
}
/**
 * Try to decode one frame off the front of `buf`. Returns null when the buffer
 * does not yet hold a complete frame, so the caller keeps accumulating. Throws
 * when the frame is malformed or oversized — the caller must then close.
 */
export declare function decodeFrame(buf: Buffer): DecodedFrame | null;
export interface WsServer {
    readonly port: number;
    close(): Promise<void>;
    connections(): WsConnection[];
}
/**
 * Start a loopback WebSocket server. Resolves once it is accepting
 * connections; rejects if the port cannot be bound.
 */
export declare function startWsServer(port: number, handlers: WsServerHandlers): Promise<WsServer>;