Add support for passing a custom http agent

There are times that you'd need to have a custom http agent for making
the authentication requests (via openid-client). This can allow a user
to provide their own agent so that they can proxy or do other things
that they'd like to do.

src/auth0-session/client/node-client.ts

@@ -61,7 +61,8 @@ export class NodeClient extends AbstractClient {
             }
           : undefined)
       },
-      timeout: config.httpTimeout
+      timeout: config.httpTimeout,
+      agent: config.httpAgent
     });
     const applyHttpOptionsCustom = (entity: Issuer<Client> | typeof Issuer | Client) => {
       entity[custom.http_options] = defaultHttpOptions;

src/auth0-session/config.ts

@@ -2,6 +2,7 @@ import type {
   AuthorizationParameters as OidcAuthorizationParameters,
   ClientAuthMethod
 } from './client/abstract-client';
+import type { Agent } from 'https';
 import { SessionStore } from './session/stateful-session';
 
 /**
@@ -100,6 +101,11 @@ export interface Config {
    */
   httpTimeout: number;
 
+  /**
+   * Instance of an HTTP agent for authentication requests.
+   */
+  httpAgent?: Agent;
+
   /**
    * Boolean value to opt-out of sending the library and Node.js version to your authorization server
    * via the `Auth0-Client` header. Defaults to `true`.

src/config.ts

@@ -1,3 +1,4 @@
+import type { Agent } from 'https';
 import type { LoginOptions, AuthorizationParameters as OidcAuthorizationParameters } from './auth0-session/config';
 import { SessionStore } from './auth0-session/session/stateful-session';
 import Session from './session/session';
@@ -96,6 +97,11 @@ export interface BaseConfig {
    */
   httpTimeout: number;
 
+  /**
+   * Instance of an HTTP agent for authentication requests.
+   */
+  httpAgent?: Agent;
+
   /**
    * Boolean value to opt-out of sending the library and node version to your authorization server
    * via the `Auth0-Client` header. Defaults to `true`.