Files
letro-ios/ElementX/Sources/Screens/Authentication/OIDCAuthenticationPresenter.swift

119 lines
5.0 KiB
Swift

//
// Copyright 2023 New Vector Ltd
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
import AuthenticationServices
/// Presents a web authentication session for an OIDC request.
@MainActor
class OIDCAuthenticationPresenter: NSObject {
private let authenticationService: AuthenticationServiceProxyProtocol
private let oidcRedirectURL: URL
private let presentationAnchor: UIWindow
/// The data required to complete a request.
struct Request {
let session: ASWebAuthenticationSession
let oidcData: OIDCAuthenticationDataProxy
let continuation: CheckedContinuation<Result<UserSessionProtocol, AuthenticationServiceError>, Never>
}
/// The current request in progress. This is a single use value and will be moved on access.
@Consumable private var request: Request?
init(authenticationService: AuthenticationServiceProxyProtocol, oidcRedirectURL: URL, presentationAnchor: UIWindow) {
self.authenticationService = authenticationService
self.oidcRedirectURL = oidcRedirectURL
self.presentationAnchor = presentationAnchor
super.init()
}
/// Presents a web authentication session for the supplied data.
func authenticate(using oidcData: OIDCAuthenticationDataProxy) async -> Result<UserSessionProtocol, AuthenticationServiceError> {
await withCheckedContinuation { continuation in
let session = ASWebAuthenticationSession(url: oidcData.url,
callbackURLScheme: oidcRedirectURL.scheme) { [weak self] url, error in
// This closure won't be called if the scheme is https, see handleUniversalLinkCallback for more info.
guard let self else { return }
guard let url else {
// Check for user cancellation to avoid showing an alert in that instance.
if let nsError = error as? NSError,
nsError.domain == ASWebAuthenticationSessionErrorDomain,
nsError.code == ASWebAuthenticationSessionError.canceledLogin.rawValue {
self.completeAuthentication(throwing: .oidcError(.userCancellation))
return
}
self.completeAuthentication(throwing: .oidcError(.unknown))
return
}
completeAuthentication(callbackURL: url)
}
session.prefersEphemeralWebBrowserSession = false
session.presentationContextProvider = self
request = Request(session: session, oidcData: oidcData, continuation: continuation)
session.start()
}
}
/// This method will be used if the `appSettings.oidcRedirectURL`'s scheme is `https`.
/// When using a custom scheme, the redirect will be handled by the web auth session's closure.
func handleUniversalLinkCallback(_ url: URL) {
completeAuthentication(callbackURL: url)
}
/// Completes the authentication by exchanging the callback URL for a user session.
private func completeAuthentication(callbackURL: URL) {
guard let request else {
MXLog.error("Failed to complete authentication. Missing request.")
return
}
if callbackURL.scheme?.starts(with: "http") == true {
request.session.cancel()
}
Task {
switch await authenticationService.loginWithOIDCCallback(callbackURL, data: request.oidcData) {
case .success(let userSession):
request.continuation.resume(returning: .success(userSession))
case .failure(let error):
request.continuation.resume(returning: .failure(error))
}
}
}
/// Aborts the authentication with the supplied error.
private func completeAuthentication(throwing error: AuthenticationServiceError) {
guard let request else {
MXLog.error("Failed to throw authentication error. Missing request.")
return
}
request.continuation.resume(returning: .failure(error))
}
}
// MARK: ASWebAuthenticationPresentationContextProviding
extension OIDCAuthenticationPresenter: ASWebAuthenticationPresentationContextProviding {
func presentationAnchor(for session: ASWebAuthenticationSession) -> ASPresentationAnchor { presentationAnchor }
}