From: Alec Armbruster <alectrocute@gmail.com>
Date: Fri, 16 Jun 2023 14:34:36 +0000 (-0400)
Subject: refactor server, tidy up, use handlers/middleware/utils pattern
X-Git-Url: http://these/git/%7B%60%24%7BwebArchiveUrl%7D/%22%7B%7D/%22https:/hacktivis.me/README.es.md?a=commitdiff_plain;h=88780ba9abf07bce52bd83851b1d6c9b63501f45;p=lemmy-ui.git

refactor server, tidy up, use handlers/middleware/utils pattern
---

diff --git a/src/server/handlers/catch-all-handler.tsx b/src/server/handlers/catch-all-handler.tsx
new file mode 100644
index 0000000..bbcb689
--- /dev/null
+++ b/src/server/handlers/catch-all-handler.tsx
@@ -0,0 +1,115 @@
+import type { Request, Response } from "express";
+import { StaticRouter, matchPath } from "inferno-router";
+import { renderToString } from "inferno-server";
+import IsomorphicCookie from "isomorphic-cookie";
+import { GetSite, GetSiteResponse, LemmyHttp } from "lemmy-js-client";
+import { App } from "../../shared/components/app/app";
+import { getHttpBaseInternal } from "../../shared/env";
+import {
+  InitialFetchRequest,
+  IsoDataOptionalSite,
+} from "../../shared/interfaces";
+import { routes } from "../../shared/routes";
+import { RequestState, wrapClient } from "../../shared/services/HttpService";
+import { ErrorPageData, initializeSite, isAuthPath } from "../../shared/utils";
+import { createSsrHtml } from "../utils/create-ssr-html";
+import { getErrorPageData } from "../utils/get-error-page-data";
+import { setForwardedHeaders } from "../utils/set-forwarded-headers";
+
+export default async (req: Request, res: Response) => {
+  try {
+    const activeRoute = routes.find(route => matchPath(req.path, route));
+    let auth: string | undefined = IsomorphicCookie.load("jwt", req);
+
+    const getSiteForm: GetSite = { auth };
+
+    const headers = setForwardedHeaders(req.headers);
+    const client = wrapClient(new LemmyHttp(getHttpBaseInternal(), headers));
+
+    const { path, url, query } = req;
+
+    // Get site data first
+    // This bypasses errors, so that the client can hit the error on its own,
+    // in order to remove the jwt on the browser. Necessary for wrong jwts
+    let site: GetSiteResponse | undefined = undefined;
+    const routeData: RequestState<any>[] = [];
+    let errorPageData: ErrorPageData | undefined = undefined;
+    let try_site = await client.getSite(getSiteForm);
+    if (try_site.state === "failed" && try_site.msg == "not_logged_in") {
+      console.error(
+        "Incorrect JWT token, skipping auth so frontend can remove jwt cookie"
+      );
+      getSiteForm.auth = undefined;
+      auth = undefined;
+      try_site = await client.getSite(getSiteForm);
+    }
+
+    if (!auth && isAuthPath(path)) {
+      return res.redirect("/login");
+    }
+
+    if (try_site.state === "success") {
+      site = try_site.data;
+      initializeSite(site);
+
+      if (path !== "/setup" && !site.site_view.local_site.site_setup) {
+        return res.redirect("/setup");
+      }
+
+      if (site) {
+        const initialFetchReq: InitialFetchRequest = {
+          client,
+          auth,
+          path,
+          query,
+          site,
+        };
+
+        if (activeRoute?.fetchInitialData) {
+          routeData.push(
+            ...(await Promise.all([
+              ...activeRoute.fetchInitialData(initialFetchReq),
+            ]))
+          );
+        }
+      }
+    } else if (try_site.state === "failed") {
+      errorPageData = getErrorPageData(new Error(try_site.msg), site);
+    }
+
+    // Redirect to the 404 if there's an API error
+    if (routeData[0] && routeData[0].state === "failed") {
+      const error = routeData[0].msg;
+      console.error(error);
+      if (error === "instance_is_private") {
+        return res.redirect(`/signup`);
+      } else {
+        errorPageData = getErrorPageData(new Error(error), site);
+      }
+    }
+
+    const isoData: IsoDataOptionalSite = {
+      path,
+      site_res: site,
+      routeData,
+      errorPageData,
+    };
+
+    const wrapper = (
+      <StaticRouter location={url} context={isoData}>
+        <App />
+      </StaticRouter>
+    );
+
+    const root = renderToString(wrapper);
+
+    res.send(await createSsrHtml(root, isoData));
+  } catch (err) {
+    // If an error is caught here, the error page couldn't even be rendered
+    console.error(err);
+    res.statusCode = 500;
+    return res.send(
+      process.env.NODE_ENV === "development" ? err.message : "Server error"
+    );
+  }
+};
diff --git a/src/server/handlers/robots-handler.tsx b/src/server/handlers/robots-handler.tsx
new file mode 100644
index 0000000..7271095
--- /dev/null
+++ b/src/server/handlers/robots-handler.tsx
@@ -0,0 +1,18 @@
+import type { Response } from "express";
+
+export default async ({ res }: { res: Response }) => {
+  res.setHeader("content-type", "text/plain; charset=utf-8");
+
+  res.send(`User-Agent: *
+  Disallow: /login
+  Disallow: /settings
+  Disallow: /create_community
+  Disallow: /create_post
+  Disallow: /create_private_message
+  Disallow: /inbox
+  Disallow: /setup
+  Disallow: /admin
+  Disallow: /password_change
+  Disallow: /search/
+  `);
+};
diff --git a/src/server/handlers/service-worker-handler.tsx b/src/server/handlers/service-worker-handler.tsx
new file mode 100644
index 0000000..886aa09
--- /dev/null
+++ b/src/server/handlers/service-worker-handler.tsx
@@ -0,0 +1,14 @@
+import type { Response } from "express";
+import path from "path";
+
+export default async ({ res }: { res: Response }) => {
+  res.setHeader("Content-Type", "application/javascript");
+
+  res.sendFile(
+    path.resolve(
+      `./dist/service-worker${
+        process.env.NODE_ENV === "development" ? "-development" : ""
+      }.js`
+    )
+  );
+};
diff --git a/src/server/handlers/theme-handler.tsx b/src/server/handlers/theme-handler.tsx
new file mode 100644
index 0000000..9f1046d
--- /dev/null
+++ b/src/server/handlers/theme-handler.tsx
@@ -0,0 +1,32 @@
+import type { Request, Response } from "express";
+import { existsSync } from "fs";
+import path from "path";
+
+const extraThemesFolder =
+  process.env["LEMMY_UI_EXTRA_THEMES_FOLDER"] || "./extra_themes";
+
+export default async (req: Request, res: Response) => {
+  res.contentType("text/css");
+
+  const theme = req.params.name;
+
+  if (!theme.endsWith(".css")) {
+    res.statusCode = 400;
+    res.send("Theme must be a css file");
+  }
+
+  const customTheme = path.resolve(`./${extraThemesFolder}/${theme}`);
+
+  if (existsSync(customTheme)) {
+    res.sendFile(customTheme);
+  } else {
+    const internalTheme = path.resolve(`./dist/assets/css/themes/${theme}`);
+
+    // If the theme doesn't exist, just send litely
+    if (existsSync(internalTheme)) {
+      res.sendFile(internalTheme);
+    } else {
+      res.sendFile(path.resolve("./dist/assets/css/themes/litely.css"));
+    }
+  }
+};
diff --git a/src/server/handlers/themes-list-handler.tsx b/src/server/handlers/themes-list-handler.tsx
new file mode 100644
index 0000000..1a54f92
--- /dev/null
+++ b/src/server/handlers/themes-list-handler.tsx
@@ -0,0 +1,7 @@
+import type { Response } from "express";
+import { buildThemeList } from "../utils/build-themes-list";
+
+export default async ({ res }: { res: Response }) => {
+  res.type("json");
+  res.send(JSON.stringify(await buildThemeList()));
+};
diff --git a/src/server/index.tsx b/src/server/index.tsx
index 3a12ad7..f109fc1 100644
--- a/src/server/index.tsx
+++ b/src/server/index.tsx
@@ -1,465 +1,38 @@
 import express from "express";
-import { existsSync } from "fs";
-import { readdir, readFile } from "fs/promises";
-import { IncomingHttpHeaders } from "http";
-import { Helmet } from "inferno-helmet";
-import { matchPath, StaticRouter } from "inferno-router";
-import { renderToString } from "inferno-server";
-import IsomorphicCookie from "isomorphic-cookie";
-import { GetSite, GetSiteResponse, LemmyHttp } from "lemmy-js-client";
 import path from "path";
 import process from "process";
-import serialize from "serialize-javascript";
-import sharp from "sharp";
-import { App } from "../shared/components/app/app";
-import { getHttpBaseExternal, getHttpBaseInternal } from "../shared/env";
-import {
-  ILemmyConfig,
-  InitialFetchRequest,
-  IsoDataOptionalSite,
-} from "../shared/interfaces";
-import { routes } from "../shared/routes";
-import { RequestState, wrapClient } from "../shared/services/HttpService";
-import {
-  ErrorPageData,
-  favIconPngUrl,
-  favIconUrl,
-  initializeSite,
-  isAuthPath,
-} from "../shared/utils";
+import CatchAllHandler from "./handlers/catch-all-handler";
+import RobotsHandler from "./handlers/robots-handler";
+import ServiceWorkerHandler from "./handlers/service-worker-handler";
+import ThemeHandler from "./handlers/theme-handler";
+import ThemesListHandler from "./handlers/themes-list-handler";
+import setDefaultCsp from "./middleware/set-default-csp";
 
 const server = express();
+
 const [hostname, port] = process.env["LEMMY_UI_HOST"]
   ? process.env["LEMMY_UI_HOST"].split(":")
   : ["0.0.0.0", "1234"];
-const extraThemesFolder =
-  process.env["LEMMY_UI_EXTRA_THEMES_FOLDER"] || "./extra_themes";
-
-if (!process.env["LEMMY_UI_DISABLE_CSP"] && !process.env["LEMMY_UI_DEBUG"]) {
-  server.use(function (_req, res, next) {
-    res.setHeader(
-      "Content-Security-Policy",
-      `default-src 'self'; manifest-src *; connect-src *; img-src * data:; script-src 'self' 'unsafe-inline' 'unsafe-eval'; style-src 'self' 'unsafe-inline'; form-action 'self'; base-uri 'self'; frame-src *; media-src *`
-    );
-    next();
-  });
-}
-const customHtmlHeader = process.env["LEMMY_UI_CUSTOM_HTML_HEADER"] || "";
 
 server.use(express.json());
 server.use(express.urlencoded({ extended: false }));
 server.use("/static", express.static(path.resolve("./dist")));
 
-const robotstxt = `User-Agent: *
-Disallow: /login
-Disallow: /settings
-Disallow: /create_community
-Disallow: /create_post
-Disallow: /create_private_message
-Disallow: /inbox
-Disallow: /setup
-Disallow: /admin
-Disallow: /password_change
-Disallow: /search/
-`;
-
-server.get("/service-worker.js", async (_req, res) => {
-  res.setHeader("Content-Type", "application/javascript");
-  res.sendFile(
-    path.resolve(
-      `./dist/service-worker${
-        process.env.NODE_ENV === "development" ? "-development" : ""
-      }.js`
-    )
-  );
-});
-
-server.get("/robots.txt", async (_req, res) => {
-  res.setHeader("content-type", "text/plain; charset=utf-8");
-  res.send(robotstxt);
-});
-
-server.get("/css/themes/:name", async (req, res) => {
-  res.contentType("text/css");
-  const theme = req.params.name;
-  if (!theme.endsWith(".css")) {
-    res.statusCode = 400;
-    res.send("Theme must be a css file");
-  }
-
-  const customTheme = path.resolve(`./${extraThemesFolder}/${theme}`);
-  if (existsSync(customTheme)) {
-    res.sendFile(customTheme);
-  } else {
-    const internalTheme = path.resolve(`./dist/assets/css/themes/${theme}`);
-
-    // If the theme doesn't exist, just send litely
-    if (existsSync(internalTheme)) {
-      res.sendFile(internalTheme);
-    } else {
-      res.sendFile(path.resolve("./dist/assets/css/themes/litely.css"));
-    }
-  }
-});
-
-async function buildThemeList(): Promise<string[]> {
-  const themes = ["darkly", "darkly-red", "litely", "litely-red"];
-  if (existsSync(extraThemesFolder)) {
-    const dirThemes = await readdir(extraThemesFolder);
-    const cssThemes = dirThemes
-      .filter(d => d.endsWith(".css"))
-      .map(d => d.replace(".css", ""));
-    themes.push(...cssThemes);
-  }
-  return themes;
+if (!process.env["LEMMY_UI_DISABLE_CSP"] && !process.env["LEMMY_UI_DEBUG"]) {
+  server.use(setDefaultCsp);
 }
 
-server.get("/css/themelist", async (_req, res) => {
-  res.type("json");
-  res.send(JSON.stringify(await buildThemeList()));
-});
-
-// server.use(cookieParser());
-server.get("/*", async (req, res) => {
-  try {
-    const activeRoute = routes.find(route => matchPath(req.path, route));
-    let auth: string | undefined = IsomorphicCookie.load("jwt", req);
-
-    const getSiteForm: GetSite = { auth };
-
-    const headers = setForwardedHeaders(req.headers);
-    const client = wrapClient(new LemmyHttp(getHttpBaseInternal(), headers));
-
-    const { path, url, query } = req;
-
-    // Get site data first
-    // This bypasses errors, so that the client can hit the error on its own,
-    // in order to remove the jwt on the browser. Necessary for wrong jwts
-    let site: GetSiteResponse | undefined = undefined;
-    const routeData: RequestState<any>[] = [];
-    let errorPageData: ErrorPageData | undefined = undefined;
-    let try_site = await client.getSite(getSiteForm);
-    if (try_site.state === "failed" && try_site.msg == "not_logged_in") {
-      console.error(
-        "Incorrect JWT token, skipping auth so frontend can remove jwt cookie"
-      );
-      getSiteForm.auth = undefined;
-      auth = undefined;
-      try_site = await client.getSite(getSiteForm);
-    }
-
-    if (!auth && isAuthPath(path)) {
-      return res.redirect("/login");
-    }
-
-    if (try_site.state === "success") {
-      site = try_site.data;
-      initializeSite(site);
-
-      if (path !== "/setup" && !site.site_view.local_site.site_setup) {
-        return res.redirect("/setup");
-      }
-
-      if (site) {
-        const initialFetchReq: InitialFetchRequest = {
-          client,
-          auth,
-          path,
-          query,
-          site,
-        };
-
-        if (activeRoute?.fetchInitialData) {
-          routeData.push(
-            ...(await Promise.all([
-              ...activeRoute.fetchInitialData(initialFetchReq),
-            ]))
-          );
-        }
-      }
-    } else if (try_site.state === "failed") {
-      errorPageData = getErrorPageData(new Error(try_site.msg), site);
-    }
-
-    // Redirect to the 404 if there's an API error
-    if (routeData[0] && routeData[0].state === "failed") {
-      const error = routeData[0].msg;
-      console.error(error);
-      if (error === "instance_is_private") {
-        return res.redirect(`/signup`);
-      } else {
-        errorPageData = getErrorPageData(new Error(error), site);
-      }
-    }
-
-    const isoData: IsoDataOptionalSite = {
-      path,
-      site_res: site,
-      routeData,
-      errorPageData,
-    };
-
-    const wrapper = (
-      <StaticRouter location={url} context={isoData}>
-        <App />
-      </StaticRouter>
-    );
-
-    const root = renderToString(wrapper);
-
-    res.send(await createSsrHtml(root, isoData));
-  } catch (err) {
-    // If an error is caught here, the error page couldn't even be rendered
-    console.error(err);
-    res.statusCode = 500;
-    return res.send(
-      process.env.NODE_ENV === "development" ? err.message : "Server error"
-    );
-  }
-});
+server.get("/robots.txt", RobotsHandler);
+server.get("/service-worker.js", ServiceWorkerHandler);
+server.get("/css/themes/:name", ThemeHandler);
+server.get("/css/themelist", ThemesListHandler);
+server.get("/*", CatchAllHandler);
 
 server.listen(Number(port), hostname, () => {
   console.log(`http://${hostname}:${port}`);
 });
 
-function setForwardedHeaders(headers: IncomingHttpHeaders): {
-  [key: string]: string;
-} {
-  const out: { [key: string]: string } = {};
-  if (headers.host) {
-    out.host = headers.host;
-  }
-  const realIp = headers["x-real-ip"];
-  if (realIp) {
-    out["x-real-ip"] = realIp as string;
-  }
-  const forwardedFor = headers["x-forwarded-for"];
-  if (forwardedFor) {
-    out["x-forwarded-for"] = forwardedFor as string;
-  }
-
-  return out;
-}
-
 process.on("SIGINT", () => {
   console.info("Interrupted");
   process.exit(0);
 });
-
-const iconSizes = [72, 96, 144, 192, 512];
-const defaultLogoPathDirectory = path.join(
-  process.cwd(),
-  "dist",
-  "assets",
-  "icons"
-);
-
-export async function generateManifestBase64({
-  my_user,
-  site_view: {
-    site,
-    local_site: { community_creation_admin_only },
-  },
-}: GetSiteResponse) {
-  const url = getHttpBaseExternal();
-
-  const icon = site.icon ? await fetchIconPng(site.icon) : null;
-
-  const manifest = {
-    name: site.name,
-    description: site.description ?? "A link aggregator for the fediverse",
-    start_url: url,
-    scope: url,
-    display: "standalone",
-    id: "/",
-    background_color: "#222222",
-    theme_color: "#222222",
-    icons: await Promise.all(
-      iconSizes.map(async size => {
-        let src = await readFile(
-          path.join(defaultLogoPathDirectory, `icon-${size}x${size}.png`)
-        ).then(buf => buf.toString("base64"));
-
-        if (icon) {
-          src = await sharp(icon)
-            .resize(size, size)
-            .png()
-            .toBuffer()
-            .then(buf => buf.toString("base64"));
-        }
-
-        return {
-          sizes: `${size}x${size}`,
-          type: "image/png",
-          src: `data:image/png;base64,${src}`,
-          purpose: "any maskable",
-        };
-      })
-    ),
-    shortcuts: [
-      {
-        name: "Search",
-        short_name: "Search",
-        description: "Perform a search.",
-        url: "/search",
-      },
-      {
-        name: "Communities",
-        url: "/communities",
-        short_name: "Communities",
-        description: "Browse communities",
-      },
-    ]
-      .concat(
-        my_user
-          ? [
-              {
-                name: "Create Post",
-                url: "/create_post",
-                short_name: "Create Post",
-                description: "Create a post.",
-              },
-            ]
-          : []
-      )
-      .concat(
-        my_user?.local_user_view.person.admin || !community_creation_admin_only
-          ? [
-              {
-                name: "Create Community",
-                url: "/create_community",
-                short_name: "Create Community",
-                description: "Create a community",
-              },
-            ]
-          : []
-      ),
-    related_applications: [
-      {
-        platform: "f-droid",
-        url: "https://f-droid.org/packages/com.jerboa/",
-        id: "com.jerboa",
-      },
-    ],
-  };
-
-  return Buffer.from(JSON.stringify(manifest)).toString("base64");
-}
-
-async function fetchIconPng(iconUrl: string) {
-  return await fetch(iconUrl)
-    .then(res => res.blob())
-    .then(blob => blob.arrayBuffer());
-}
-
-function getErrorPageData(error: Error, site?: GetSiteResponse) {
-  const errorPageData: ErrorPageData = {};
-
-  if (site) {
-    errorPageData.error = error.message;
-  }
-
-  const adminMatrixIds = site?.admins
-    .map(({ person: { matrix_user_id } }) => matrix_user_id)
-    .filter(id => id) as string[] | undefined;
-  if (adminMatrixIds && adminMatrixIds.length > 0) {
-    errorPageData.adminMatrixIds = adminMatrixIds;
-  }
-
-  return errorPageData;
-}
-
-async function createSsrHtml(root: string, isoData: IsoDataOptionalSite) {
-  const site = isoData.site_res;
-  const appleTouchIcon = site?.site_view.site.icon
-    ? `data:image/png;base64,${sharp(
-        await fetchIconPng(site.site_view.site.icon)
-      )
-        .resize(180, 180)
-        .extend({
-          bottom: 20,
-          top: 20,
-          left: 20,
-          right: 20,
-          background: "#222222",
-        })
-        .png()
-        .toBuffer()
-        .then(buf => buf.toString("base64"))}`
-    : favIconPngUrl;
-
-  const erudaStr =
-    process.env["LEMMY_UI_DEBUG"] === "true"
-      ? renderToString(
-          <>
-            <script src="//cdn.jsdelivr.net/npm/eruda"></script>
-            <script>eruda.init();</script>
-          </>
-        )
-      : "";
-
-  const helmet = Helmet.renderStatic();
-
-  const config: ILemmyConfig = { wsHost: process.env.LEMMY_UI_LEMMY_WS_HOST };
-
-  return `
-  <!DOCTYPE html>
-  <html ${helmet.htmlAttributes.toString()}>
-  <head>
-  <script>window.isoData = ${serialize(isoData)}</script>
-  <script>window.lemmyConfig = ${serialize(config)}</script>
-
-  <!-- A remote debugging utility for mobile -->
-  ${erudaStr}
-
-  <!-- Custom injected script -->
-  ${customHtmlHeader}
-
-  ${helmet.title.toString()}
-  ${helmet.meta.toString()}
-
-  <!-- Required meta tags -->
-  <meta name="Description" content="Lemmy">
-  <meta charset="utf-8">
-  <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no, user-scalable=no">
-  <link
-     id="favicon"
-     rel="shortcut icon"
-     type="image/x-icon"
-     href=${site?.site_view.site.icon ?? favIconUrl}
-   />
-
-  <!-- Web app manifest -->
-  ${
-    site &&
-    `<link
-        rel="manifest"
-        href=${`data:application/manifest+json;base64,${await generateManifestBase64(
-          site
-        )}`}
-      />`
-  }
-  <link rel="apple-touch-icon" href=${appleTouchIcon} />
-  <link rel="apple-touch-startup-image" href=${appleTouchIcon} />
-
-  <!-- Styles -->
-  <link rel="stylesheet" type="text/css" href="/static/styles/styles.css" />
-
-  <!-- Current theme and more -->
-  ${helmet.link.toString()}
-  
-  </head>
-
-  <body ${helmet.bodyAttributes.toString()}>
-    <noscript>
-      <div class="alert alert-danger rounded-0" role="alert">
-        <b>Javascript is disabled. Actions will not work.</b>
-      </div>
-    </noscript>
-
-    <div id='root'>${root}</div>
-    <script defer src='/static/js/client.js'></script>
-  </body>
-</html>
-`;
-}
diff --git a/src/server/middleware/set-default-csp.ts b/src/server/middleware/set-default-csp.ts
new file mode 100644
index 0000000..5b6f72a
--- /dev/null
+++ b/src/server/middleware/set-default-csp.ts
@@ -0,0 +1,9 @@
+import type { NextFunction, Response } from "express";
+
+export default function ({ res, next }: { res: Response; next: NextFunction }) {
+  res.setHeader(
+    "Content-Security-Policy",
+    `default-src 'self'; manifest-src *; connect-src *; img-src * data:; script-src 'self' 'unsafe-inline' 'unsafe-eval'; style-src 'self' 'unsafe-inline'; form-action 'self'; base-uri 'self'; frame-src *; media-src *`
+  );
+  next();
+}
diff --git a/src/server/utils/build-themes-list.ts b/src/server/utils/build-themes-list.ts
new file mode 100644
index 0000000..c6aa770
--- /dev/null
+++ b/src/server/utils/build-themes-list.ts
@@ -0,0 +1,17 @@
+import { existsSync } from "fs";
+import { readdir } from "fs/promises";
+
+const extraThemesFolder =
+  process.env["LEMMY_UI_EXTRA_THEMES_FOLDER"] || "./extra_themes";
+
+export async function buildThemeList(): Promise<string[]> {
+  const themes = ["darkly", "darkly-red", "litely", "litely-red"];
+  if (existsSync(extraThemesFolder)) {
+    const dirThemes = await readdir(extraThemesFolder);
+    const cssThemes = dirThemes
+      .filter(d => d.endsWith(".css"))
+      .map(d => d.replace(".css", ""));
+    themes.push(...cssThemes);
+  }
+  return themes;
+}
diff --git a/src/server/utils/create-ssr-html.tsx b/src/server/utils/create-ssr-html.tsx
new file mode 100644
index 0000000..d23c6da
--- /dev/null
+++ b/src/server/utils/create-ssr-html.tsx
@@ -0,0 +1,108 @@
+import { Helmet } from "inferno-helmet";
+import { renderToString } from "inferno-server";
+import serialize from "serialize-javascript";
+import sharp from "sharp";
+import { ILemmyConfig, IsoDataOptionalSite } from "../../shared/interfaces";
+import { favIconPngUrl, favIconUrl } from "../../shared/utils";
+import { fetchIconPng } from "./fetch-icon-png";
+import { generateManifestBase64 } from "./generate-manifest-base64";
+
+const customHtmlHeader = process.env["LEMMY_UI_CUSTOM_HTML_HEADER"] || "";
+
+export async function createSsrHtml(
+  root: string,
+  isoData: IsoDataOptionalSite
+) {
+  const site = isoData.site_res;
+  const appleTouchIcon = site?.site_view.site.icon
+    ? `data:image/png;base64,${sharp(
+        await fetchIconPng(site.site_view.site.icon)
+      )
+        .resize(180, 180)
+        .extend({
+          bottom: 20,
+          top: 20,
+          left: 20,
+          right: 20,
+          background: "#222222",
+        })
+        .png()
+        .toBuffer()
+        .then(buf => buf.toString("base64"))}`
+    : favIconPngUrl;
+
+  const erudaStr =
+    process.env["LEMMY_UI_DEBUG"] === "true"
+      ? renderToString(
+          <>
+            <script src="//cdn.jsdelivr.net/npm/eruda"></script>
+            <script>eruda.init();</script>
+          </>
+        )
+      : "";
+
+  const helmet = Helmet.renderStatic();
+
+  const config: ILemmyConfig = { wsHost: process.env.LEMMY_UI_LEMMY_WS_HOST };
+
+  return `
+    <!DOCTYPE html>
+    <html ${helmet.htmlAttributes.toString()}>
+    <head>
+    <script>window.isoData = ${serialize(isoData)}</script>
+    <script>window.lemmyConfig = ${serialize(config)}</script>
+  
+    <!-- A remote debugging utility for mobile -->
+    ${erudaStr}
+  
+    <!-- Custom injected script -->
+    ${customHtmlHeader}
+  
+    ${helmet.title.toString()}
+    ${helmet.meta.toString()}
+  
+    <!-- Required meta tags -->
+    <meta name="Description" content="Lemmy">
+    <meta charset="utf-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no, user-scalable=no">
+    <link
+       id="favicon"
+       rel="shortcut icon"
+       type="image/x-icon"
+       href=${site?.site_view.site.icon ?? favIconUrl}
+     />
+  
+    <!-- Web app manifest -->
+    ${
+      site &&
+      `<link
+          rel="manifest"
+          href=${`data:application/manifest+json;base64,${await generateManifestBase64(
+            site
+          )}`}
+        />`
+    }
+    <link rel="apple-touch-icon" href=${appleTouchIcon} />
+    <link rel="apple-touch-startup-image" href=${appleTouchIcon} />
+  
+    <!-- Styles -->
+    <link rel="stylesheet" type="text/css" href="/static/styles/styles.css" />
+  
+    <!-- Current theme and more -->
+    ${helmet.link.toString()}
+    
+    </head>
+  
+    <body ${helmet.bodyAttributes.toString()}>
+      <noscript>
+        <div class="alert alert-danger rounded-0" role="alert">
+          <b>Javascript is disabled. Actions will not work.</b>
+        </div>
+      </noscript>
+  
+      <div id='root'>${root}</div>
+      <script defer src='/static/js/client.js'></script>
+    </body>
+  </html>
+  `;
+}
diff --git a/src/server/utils/fetch-icon-png.ts b/src/server/utils/fetch-icon-png.ts
new file mode 100644
index 0000000..12b09e7
--- /dev/null
+++ b/src/server/utils/fetch-icon-png.ts
@@ -0,0 +1,5 @@
+export async function fetchIconPng(iconUrl: string) {
+  return await fetch(iconUrl)
+    .then(res => res.blob())
+    .then(blob => blob.arrayBuffer());
+}
diff --git a/src/server/utils/generate-manifest-base64.ts b/src/server/utils/generate-manifest-base64.ts
new file mode 100644
index 0000000..e89b155
--- /dev/null
+++ b/src/server/utils/generate-manifest-base64.ts
@@ -0,0 +1,107 @@
+import { readFile } from "fs/promises";
+import { GetSiteResponse } from "lemmy-js-client";
+import path from "path";
+import sharp from "sharp";
+import { getHttpBaseExternal } from "../../shared/env";
+import { fetchIconPng } from "./fetch-icon-png";
+
+const iconSizes = [72, 96, 144, 192, 512];
+
+const defaultLogoPathDirectory = path.join(
+  process.cwd(),
+  "dist",
+  "assets",
+  "icons"
+);
+
+export async function generateManifestBase64({
+  my_user,
+  site_view: {
+    site,
+    local_site: { community_creation_admin_only },
+  },
+}: GetSiteResponse) {
+  const url = getHttpBaseExternal();
+
+  const icon = site.icon ? await fetchIconPng(site.icon) : null;
+
+  const manifest = {
+    name: site.name,
+    description: site.description ?? "A link aggregator for the fediverse",
+    start_url: url,
+    scope: url,
+    display: "standalone",
+    id: "/",
+    background_color: "#222222",
+    theme_color: "#222222",
+    icons: await Promise.all(
+      iconSizes.map(async size => {
+        let src = await readFile(
+          path.join(defaultLogoPathDirectory, `icon-${size}x${size}.png`)
+        ).then(buf => buf.toString("base64"));
+
+        if (icon) {
+          src = await sharp(icon)
+            .resize(size, size)
+            .png()
+            .toBuffer()
+            .then(buf => buf.toString("base64"));
+        }
+
+        return {
+          sizes: `${size}x${size}`,
+          type: "image/png",
+          src: `data:image/png;base64,${src}`,
+          purpose: "any maskable",
+        };
+      })
+    ),
+    shortcuts: [
+      {
+        name: "Search",
+        short_name: "Search",
+        description: "Perform a search.",
+        url: "/search",
+      },
+      {
+        name: "Communities",
+        url: "/communities",
+        short_name: "Communities",
+        description: "Browse communities",
+      },
+    ]
+      .concat(
+        my_user
+          ? [
+              {
+                name: "Create Post",
+                url: "/create_post",
+                short_name: "Create Post",
+                description: "Create a post.",
+              },
+            ]
+          : []
+      )
+      .concat(
+        my_user?.local_user_view.person.admin || !community_creation_admin_only
+          ? [
+              {
+                name: "Create Community",
+                url: "/create_community",
+                short_name: "Create Community",
+                description: "Create a community",
+              },
+            ]
+          : []
+      ),
+    related_applications: [
+      {
+        platform: "f-droid",
+        url: "https://f-droid.org/packages/com.jerboa/",
+        id: "com.jerboa",
+      },
+    ],
+  };
+
+  return Buffer.from(JSON.stringify(manifest)).toString("base64");
+}
diff --git a/src/server/utils/get-error-page-data.ts b/src/server/utils/get-error-page-data.ts
new file mode 100644
index 0000000..af5c811
--- /dev/null
+++ b/src/server/utils/get-error-page-data.ts
@@ -0,0 +1,19 @@
+import { GetSiteResponse } from "lemmy-js-client";
+import { ErrorPageData } from "../../shared/utils";
+
+export function getErrorPageData(error: Error, site?: GetSiteResponse) {
+  const errorPageData: ErrorPageData = {};
+
+  if (site) {
+    errorPageData.error = error.message;
+  }
+
+  const adminMatrixIds = site?.admins
+    .map(({ person: { matrix_user_id } }) => matrix_user_id)
+    .filter(id => id) as string[] | undefined;
+  if (adminMatrixIds && adminMatrixIds.length > 0) {
+    errorPageData.adminMatrixIds = adminMatrixIds;
+  }
+
+  return errorPageData;
+}
diff --git a/src/server/utils/set-forwarded-headers.ts b/src/server/utils/set-forwarded-headers.ts
new file mode 100644
index 0000000..d825c60
--- /dev/null
+++ b/src/server/utils/set-forwarded-headers.ts
@@ -0,0 +1,20 @@
+import { IncomingHttpHeaders } from "http";
+
+export function setForwardedHeaders(headers: IncomingHttpHeaders): {
+  [key: string]: string;
+} {
+  const out: { [key: string]: string } = {};
+  if (headers.host) {
+    out.host = headers.host;
+  }
+  const realIp = headers["x-real-ip"];
+  if (realIp) {
+    out["x-real-ip"] = realIp as string;
+  }
+  const forwardedFor = headers["x-forwarded-for"];
+  if (forwardedFor) {
+    out["x-forwarded-for"] = forwardedFor as string;
+  }
+
+  return out;
+}