1 files changed, 164 insertions, 0 deletions
diff --git a/api/auth/authentication.ts b/api/auth/authentication.ts
new file mode 100644
index 0000000..80966bc
--- /dev/null
+++ b/api/auth/authentication.ts
@@ -0,0 +1,164 @@
+import type { AuthenticationResponseJSON } from '@simplewebauthn/server/script/deps';
+import type { VercelRequest, VercelResponse } from '@vercel/node';
+import generateAuthenticationOptions from './_generateAuthenticationOptions';
+import { getFirstQueryParam } from '_getFirstQueryParam';
+import getUser from 'db/_getUser';
+import setCurrentChallenge from 'db/_setCurrentChallenge';
+import getCurrentChallenge from 'db/_getCurrentChallenge';
+import verifyAuthenticationResponse from './_verifyAuthenticationResponse';
+import updateAuthenticator from 'db/_updateAuthenticator';
+import getAuthenticators from 'db/_getAuthenticators';
+
+/**
+  * # authentication
+  * 
+  * ## GET
+  *
+  * Generates authentication options.
+  *
+  * ### Parameters
+  *
+  * - `userId: string`. A user must exist with this ID.
+  *
+  * ### Responses
+  *
+  * - `200 OK`: Authentication options. Client should consume these using
+  *   \@simplewebauthn/browser’s `startAuthentication()` method.
+  * - `400 BAD REQUEST`: No `userId` was provided.
+  * - `404 NOT FOUND`: No user exists with the provided `userId`.
+  *
+  * ## POST
+  *
+  * Verifies authentication response from \@simplewebauthn/browser’s
+  * `startAuthentication()` method.
+  *
+  * ### Parameters
+  *
+  * - `userId: string`. A user must exist with this ID, and must have an
+  *   existing challenge and at least one authenticator in the database.
+  * - `authenticationResponse: AuthenticationResponseJSON`. The response from
+  *   \@simplewebauthn/browser’s `startAuthentication()` method.
+  *
+  * ### Responses
+  *
+  * - `200 OK`: Returns a boolean string. `'true'` if verification was
+  *   successful, and `'false'` otherwise.
+  * - `400 BAD REQUEST`: No `userId` was provided.
+  * - `404 NOT FOUND`: No user exists with the provided `userId`.
+  * - `500 INTERNAL SERVER ERROR`: The user with the provided `userId` did not
+  *   have any existing challenges or authenticators in the database.
+  * - `501 NOT IMPLEMENTED`: The user with the provided `userId` had more than
+  *   one authenticator in the database. This is not yet supported.
+  */
+export default async function handler(request: VercelRequest, response: VercelResponse): Promise<void> {
+  if (request.method === 'GET') {
+    (await handleGet(request))(response);
+    return;
+  }
+
+  else if (request.method === 'POST') {
+    (await handlePost(request))(response);
+    return;
+  }
+}
+
+async function handleGet(request: VercelRequest): Promise<(r: VercelResponse) => void> {
+  const userId = getFirstQueryParam('userId', request.query);
+
+  if (!userId) {
+    return (response) => void (
+      response.status(400).send('Expected body to contain userId, but none provided.')
+    );
+  }
+
+  const user = await getUser(userId);
+  if (!user) {
+    return (response) => void (
+      response.status(404).send(`
+        Failed to generate authentication options because there was no user
+        with the ID ${userId}.
+      `)
+    );
+  }
+
+  const options = await generateAuthenticationOptions(user);
+  
+  await setCurrentChallenge(user.id, options.challenge);
+  return (response) => void response.json(options);
+}
+
+async function handlePost(request: VercelRequest): Promise<(r: VercelResponse) => void> {
+  type Body = {
+    userId: string;
+    authenticationResponse: AuthenticationResponseJSON;
+  };
+  const { userId, authenticationResponse }: Body = request.body;
+
+  if (!userId) {
+    return (response) => void (
+      response.status(400).send('Expected body to contain userId, but none provided.')
+    );
+  }
+
+  if (!authenticationResponse) {
+    return (response) => void (
+      response.status(400).send('Expected body to contain authenticationResponse, but none provided.')
+    );
+  }
+
+  const user = await getUser(userId);
+  if (!user) {
+    return (response) => void (
+      response.status(404).send(`
+        Failed to verify authentication response because no user existed with
+        ID ${userId}.
+      `)
+    );
+  }
+
+  const expectedChallenge = await getCurrentChallenge(userId);
+  if (!expectedChallenge) {
+    return (response) => void (
+      response.status(500).send(`
+      Failed to verify authentication response because user with ID ${userId}
+      did not have any existing challenges in the database.
+    `)
+    );
+  }
+
+  const authenticators = await getAuthenticators(user.id, ['id', 'publicKey', 'counter', 'transports']);
+  if (!authenticators || authenticators.length === 0) {
+    return (response) => void (
+      response.status(500).send(`
+        Failed to verify authentication response because user with ID ${userId}
+        did not have any authenticators in the database.
+      `)
+    );
+  } else if (authenticators.length > 1) {
+    // TODO: implement support for multiple authenticators
+    return (response) => void (
+      response.status(501).send(`
+        Failed to verify authentication response because user with ID ${userId}
+        had more than one authenticator in the database. We only currently
+        support a single authenticator per user.
+      `)
+    );
+  }
+
+  const isVerified = await verifyAuthenticationResponse(
+    authenticators[0],
+    authenticationResponse,
+    expectedChallenge
+  );
+
+  if (isVerified) {
+    for (const authenticator of authenticators) {
+      updateAuthenticator(authenticator.id, { counter: authenticator.counter + 1 });
+    }
+  }
+
+  return (response) => void (
+    response.status(200).send(isVerified ? 'true' : 'false')
+  );
+}
+