import { ENR } from "../enr";
export declare type SearchContext = {
    domain: string;
    publicKey: string;
    visits: {
        [key: string]: boolean;
    };
};
export interface DnsClient {
    resolveTXT: (domain: string) => Promise<string[]>;
}
export interface NodeCapabilityCount {
    relay: number;
    store: number;
    filter: number;
    lightPush: number;
}
export declare class DnsNodeDiscovery {
    private readonly dns;
    private readonly _DNSTreeCache;
    private readonly _errorTolerance;
    static dnsOverHttp(dnsClient?: DnsClient): DnsNodeDiscovery;
    /**
     * Returns a list of verified peers listed in an EIP-1459 DNS tree. Method may
     * return fewer peers than requested if [[wantedNodeCapabilityCount]] requires
     * larger quantity of peers than available or the number of errors/duplicate
     * peers encountered by randomized search exceeds the sum of the fields of
     * [[wantedNodeCapabilityCount]] plus the [[_errorTolerance]] factor.
     */
    getPeers(enrTreeUrls: string[], wantedNodeCapabilityCount: Partial<NodeCapabilityCount>): Promise<ENR[]>;
    constructor(dns: DnsClient);
    /**
     * {@docInherit getPeers}
     */
    getNextPeer(enrTreeUrls: string[], wantedNodeCapabilityCount: Partial<NodeCapabilityCount>): AsyncGenerator<ENR>;
    /**
     * Runs a recursive, randomized descent of the DNS tree to retrieve a single
     * ENR record as an ENR. Returns null if parsing or DNS resolution fails.
     */
    private _search;
    /**
     * Retrieves the TXT record stored at a location from either
     * this DNS tree cache or via DNS query.
     *
     * @throws if the TXT Record contains non-UTF-8 values.
     */
    private _getTXTRecord;
}