Feature: homepage auth (#6769)

src/pages/api/auth/[...nextauth].js

@@ -0,0 +1,114 @@
+import { timingSafeEqual } from "node:crypto";
+
+import NextAuth from "next-auth";
+import CredentialsProvider from "next-auth/providers/credentials";
+
+const authEnabled = Boolean(process.env.HOMEPAGE_AUTH_ENABLED);
+const issuer = process.env.HOMEPAGE_OIDC_ISSUER;
+const clientId = process.env.HOMEPAGE_OIDC_CLIENT_ID;
+const clientSecret = process.env.HOMEPAGE_OIDC_CLIENT_SECRET;
+const homepageAuthSecret = process.env.HOMEPAGE_AUTH_SECRET;
+const homepageExternalUrl = process.env.HOMEPAGE_EXTERNAL_URL;
+const homepageAuthPassword = process.env.HOMEPAGE_AUTH_PASSWORD;
+
+// Map HOMEPAGE_* envs to what NextAuth expects
+if (!process.env.NEXTAUTH_SECRET && homepageAuthSecret) {
+  process.env.NEXTAUTH_SECRET = homepageAuthSecret;
+}
+if (!process.env.NEXTAUTH_URL && homepageExternalUrl) {
+  process.env.NEXTAUTH_URL = homepageExternalUrl;
+}
+
+const defaultScope = process.env.HOMEPAGE_OIDC_SCOPE || "openid email profile";
+const cleanedIssuer = issuer ? issuer.replace(/\/+$/, "") : issuer;
+const hasOidcConfig = Boolean(issuer && clientId && clientSecret);
+const hasAnyOidcConfig = Boolean(issuer || clientId || clientSecret);
+
+if (authEnabled) {
+  if (hasOidcConfig) {
+    if (!process.env.NEXTAUTH_SECRET || !process.env.NEXTAUTH_URL) {
+      throw new Error("OIDC auth is enabled but required settings are missing.");
+    }
+  } else if (hasAnyOidcConfig) {
+    throw new Error("OIDC auth is enabled but required settings are missing.");
+  } else if (!homepageAuthPassword || !process.env.NEXTAUTH_SECRET) {
+    throw new Error("Password auth is enabled but required settings are missing.");
+  }
+}
+
+let providers = [];
+if (authEnabled) {
+  if (hasOidcConfig) {
+    providers = [
+      {
+        id: "homepage-oidc",
+        name: process.env.HOMEPAGE_OIDC_NAME || "Homepage OIDC",
+        type: "oauth",
+        idToken: true,
+        issuer: cleanedIssuer,
+        wellKnown: `${cleanedIssuer}/.well-known/openid-configuration`,
+        clientId,
+        clientSecret,
+        authorization: {
+          params: {
+            scope: defaultScope,
+          },
+        },
+        profile(profile) {
+          return {
+            id: profile.sub ?? profile.id ?? profile.user_id ?? profile.uid ?? profile.email,
+            name: profile.name ?? profile.preferred_username ?? profile.nickname ?? profile.email,
+            email: profile.email ?? null,
+            image: profile.picture ?? null,
+          };
+        },
+      },
+    ];
+  } else {
+    providers = [
+      CredentialsProvider({
+        name: "Password",
+        credentials: {
+          password: { label: "Password", type: "password" },
+        },
+        async authorize(credentials) {
+          const provided = credentials?.password ?? "";
+          const expected = homepageAuthPassword ?? "";
+          if (!expected || provided.length !== expected.length) {
+            return null;
+          }
+          const isMatch = timingSafeEqual(Buffer.from(provided), Buffer.from(expected));
+          if (!isMatch) {
+            return null;
+          }
+          return {
+            id: "homepage",
+            name: "Homepage",
+          };
+        },
+      }),
+    ];
+  }
+}
+
+export default NextAuth({
+  providers,
+  session: {
+    strategy: "jwt",
+  },
+  secret: process.env.NEXTAUTH_SECRET,
+  pages: {
+    signIn: "/auth/signin",
+  },
+  debug: true,
+  logger: {
+    error: (...args) => console.error("[nextauth][error]", ...args),
+    warn: (...args) => console.warn("[nextauth][warn]", ...args),
+    debug: (...args) => console.debug("[nextauth][debug]", ...args),
+  },
+  events: {
+    signIn: async (message) => console.debug("[nextauth][event][signIn]", message),
+    signOut: async (message) => console.debug("[nextauth][event][signOut]", message),
+    error: async (message) => console.error("[nextauth][event][error]", message),
+  },
+});