export type ProxyResolution = {
    kind: 'direct';
} | {
    kind: 'proxy';
    proxy: URL;
} | {
    kind: 'unusable';
    variable: string;
    value: string;
    reason: string;
};
export declare function resolveProxyForUrl(url: URL, env?: NodeJS.ProcessEnv, npmConfigProxy?: boolean): ProxyResolution;
/**
 * The proxy `env` configures for `protocol`, before any `no_proxy` exclusion:
 * `<protocol>_proxy`, falling back to `all_proxy`, normalized as the probe
 * would use it (a value with no scheme takes the target's protocol). With
 * `npmConfigProxy`, `npm_config_<protocol>_proxy` comes first and
 * `npm_config_proxy` sits between the two.
 */
export declare function resolveProxyForProtocol(protocol: string, env?: NodeJS.ProcessEnv, npmConfigProxy?: boolean): ProxyResolution;
/**
 * The `no_proxy` entries `env` configures (`npm_config_no_proxy` first with
 * `npmConfigProxy`), lowercased and with the empty entries a separator run
 * leaves dropped. Each entry excludes hosts on its own, so their order carries
 * no meaning.
 */
export declare function noProxyEntries(env: NodeJS.ProcessEnv, npmConfigProxy?: boolean): string[];
export declare function withoutCredentials(value: string): string;