Support login_hint in passport implementation

[dennemark]

Hi,
I would like to forward userId or mail to the oidc provider via login_hint for better user experience. However passport does not support query params for the authenticate route

openid-client/src/passport.ts

Line 441 in f020185

(req.method === 'GET' && currentUrl.searchParams.size === 0) ||

Would it be enough to add login_hint similar to prompt here?

openid-client/src/passport.ts

Line 192 in f020185

if (options?.prompt) {

I am just not sure how to forward this to passport. Since typescript is not even showing me the prompt on the authenticate function, but I think it would be like this, right? passport.authenticate(provider, { login_hint: '[email protected]', prompt: 'does not exist for intellisense' })

[panva]

Yes, you'll need to call passport exactly the way you described (minus the prompt) but to enrich the authorization request parameters you'll need to overload the authorizationRequestParams method that will then receive those arguments you passed to authenticate, you'll return the additional parameters you want included in the authorization request from mthe authorizationRequestParams function.

openid-client/src/passport.ts

Lines 172 to 197 in 626749b

	/**
	* Return extra parameters to be included an authorization request.
	*/
	authorizationRequestParams<
	TOptions extends
	passport.AuthenticateOptions = passport.AuthenticateOptions,
	>(
	// @ts-ignore
	req: express.Request, options: TOptions,
	): URLSearchParams | Record<string, string> | undefined {
	let params = new URLSearchParams()
	if (options?.scope) {
	if (Array.isArray(options?.scope) && options.scope.length) {
	params.set('scope', options.scope.join(' '))
	} else if (typeof options?.scope === 'string' && options.scope.length) {
	params.set('scope', options.scope)
	}
	}
	if (options?.prompt) {
	params.set('prompt', options.prompt)
	}
	return params
	}

Why this is the way passport is when it comes to types I don't know, I am not maintaining those types (assuming you mean and installed @types/passport).

[dennemark]

thanks! should i make a pr for login_hint?

[panva]

No, the only options that are in by default are the (albeit questionable) ones that are commonly used in other passport strategies, hence why they're part of the type definition, see @types/passport.

The function is to be overloaded by design if needed.

[dennemark]

no i dont mean the types, i mean the searchParams, since i currently cannot set custom search params, if i am not mistaken. only prompts and scope are set.

[panva]

Yes. And you are expected to overload the method on the Strategy instance to make it to do more that's not part of passport's "norm"

[dennemark]

Ah now i see. Sorry, in my passport instance it did not show prompt or scope in intellisense. Thats why i was sueprised. Maybe fastify-passport has different types.
Anyways, the solution is not pretty, but i guess it will work out.
Thanks!