refactor: rewrite GreenRhombus to be a SVR.JS 4.x mod

.gitignore

@@ -0,0 +1,11 @@
+# Build output
+/dist/
+
+# SVR.JS
+/svrjs/
+
+# Dependencies
+node_modules
+
+# ESLint cache
+.eslintcache

.husky/commit-msg

@@ -0,0 +1,2 @@
+#!/bin/sh
+npx --no -- commitlint --edit "$1"

.husky/pre-commit

@@ -0,0 +1,2 @@
+#!/bin/sh
+npx lint-staged

LICENSE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2018-2024 SVR.JS
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README

@@ -0,0 +1,29 @@
+This repository contains SVR.JS mod starter code and its build system
+The mod will work for SVR.JS Nightly-GitNext.
+
+Before doing anything, run "npm install".
+To build SVR.JS mod, run "npm run build".
+To check SVR.JS mod code for errors with ESLint, run "npm run lint".
+To fix and beautify SVR.JS mod code with ESLint and Prettier, run "npm run lint:fix".
+To perform unit tests with Jest, run "npm test".
+
+To test the mod:
+1. Clone the SVR.JS repository with "git clone https://git.svrjs.org/svrjs/svrjs.git" command.
+2. Change the working directory to "svrjs" using "cd svrjs".
+3. Build SVR.JS by first running "npm install" and then running "npm run build".
+4. Copy the mod into mods directory in the dist directory using "cp ../dist/mod.js dist/mods" (GNU/Linux, Unix, BSD) or "copy ..\dist\mod.js dist\mods" (Windows).
+5. Do the necessary mod configuration if the mod requires it.
+6. Run SVR.JS by running "npm start".
+7. Do some requests to the endpoints covered by the mod.
+
+Structure:
+ - dist - contains the built SVR.JS mod
+ - src - contains SVR.JS mod source code
+   - index.js - entry point
+   - utils - utility functions
+ - tests - Jest unit tests
+   - utils - unit tests for utility functions
+ - esbuild.config.js - the build script
+ - eslint.config.js - ESLint configuration
+ - jest.config.js - Jest configuration
+ - modInfo.json - SVR.JS mod name and version

commitlint.config.js

@@ -0,0 +1,3 @@
+module.exports = {
+  extends: ["@commitlint/config-conventional"]
+};

esbuild.config.js

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+const esbuild = require("esbuild");
+
+esbuild.build({
+  entryPoints: ["src/index.js"],
+  bundle: true,
+  outfile: "dist/mod.js", // Mod output file
+  platform: "node",
+  target: "es2017",
+}).catch((err) => {
+  throw err;
+});

eslint.config.js

@@ -0,0 +1,30 @@
+const globals = require("globals");
+const pluginJs = require("@eslint/js");
+const eslintPluginPrettierRecommended = require("eslint-plugin-prettier/recommended");
+const jest = require("eslint-plugin-jest");
+
+module.exports = [
+  {
+    files: ["**/*.js"],
+    languageOptions: {
+      sourceType: "commonjs"
+    }
+  },
+  {
+    files: ["tests/*.test.js", "tests/**/*.test.js"],
+    ...jest.configs['flat/recommended'],
+    rules: {
+      ...jest.configs['flat/recommended'].rules,
+      'jest/prefer-expect-assertions': 'off',
+    }
+  },
+  {
+    languageOptions: {
+      globals: {
+        ...globals.node
+      }
+    }
+  },
+  pluginJs.configs.recommended,
+  eslintPluginPrettierRecommended
+];

jest.config.js

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+module.exports = {
+  testEnvironment: 'node',
+  testMatch: ['**/tests/**/*.test.js'],
+  verbose: true,
+};

lint-staged.config.js

@@ -0,0 +1,4 @@
+module.exports = {
+  "tests/**/*.js": "eslint --cache --fix",
+  "src/**/*.js": "eslint --cache --fix"
+};

mod.info

@@ -1,4 +0,0 @@
-{
-  "name": "GreenRhombus FastCGI client for SVR.JS",
-  "version": "Nightly-GitMain"
-}

modInfo.json

@@ -0,0 +1,4 @@
+{
+  "name": "Example mod",
+  "version": "0.0.0"
+}

package.json

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+{
+  "name": "svrjs-mod-starter",
+  "version": "0.0.0",
+  "private": true,
+  "scripts": {
+    "build": "node esbuild.config.js",
+    "cz": "cz",
+    "lint": "eslint --no-error-on-unmatched-pattern src/**/*.js src/*.js tests/**/*.test.js tests/**/*.js",
+    "lint:fix": "npm run lint -- --fix",
+    "prepare": "husky",
+    "test": "jest"
+  },
+  "devDependencies": {
+    "@commitlint/cli": "^19.6.1",
+    "@commitlint/config-conventional": "^19.6.0",
+    "@eslint/js": "^9.9.1",
+    "commitizen": "^4.3.1",
+    "cz-conventional-changelog": "^3.3.0",
+    "esbuild": "^0.23.1",
+    "eslint": "^9.9.1",
+    "eslint-config-prettier": "^9.1.0",
+    "eslint-plugin-jest": "^28.8.0",
+    "eslint-plugin-prettier": "^5.2.1",
+    "globals": "^15.9.0",
+    "husky": "^9.1.7",
+    "jest": "^29.7.0",
+    "lint-staged": "^15.2.11",
+    "prettier": "^3.3.3"
+  },
+  "config": {
+    "commitizen": {
+      "path": "./node_modules/cz-conventional-changelog"
+    }
+  }
+}

prettier.config.js

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+// prettier.config.js, .prettierrc.js, prettier.config.cjs, or .prettierrc.cjs
+
+/**
+ * @see https://prettier.io/docs/en/configuration.html
+ * @type {import("prettier").Config}
+ */
+const config = {
+  trailingComma: "none",
+  tabWidth: 2,
+  semi: true,
+  singleQuote: false,
+  endOfLine: "lf"
+};
+  
+module.exports = config;

src/index.js

@@ -0,0 +1,542 @@
+const fs = require("fs");
+const os = require("os");
+const path = require("path");
+const { FastCGIHandler } = require("./utils/fastCgi.js"); // FastCGI handler
+const createCGIParser = require("./utils/cgiParser.js"); // CGI parser
+const modInfo = require("../modInfo.json"); // SVR.JS mod information
+
+let fastcgiConfigFromSeparateFile = {};
+try {
+  fastcgiConfigFromSeparateFile = JSON.parse(
+    fs.readFileSync(process.dirname + "/greenrhombus-config.json")
+  );
+  // eslint-disable-next-line
+} catch (ex) {
+  // Use defaults
+}
+
+let scriptExtsFromSeparateFile = [];
+try {
+  scriptExtsFromSeparateFile = JSON.parse(
+    fs.readFileSync(process.dirname + "/greenrhombus-scriptexts.json")
+  );
+  // eslint-disable-next-line
+} catch (ex) {
+
+}
+
+const executeFastCGI = (
+  req,
+  res,
+  logFacilities,
+  defaultHeaders,
+  customEnv,
+  fastCGIConfig
+) => {
+  const environment = Object.assign({}, process.env, customEnv);
+  let errorBuffer = "";
+
+  const options = {
+    host: fastCGIConfig.host,
+    port: fastCGIConfig.port,
+    path: fastCGIConfig.socketPath,
+    env: environment
+  };
+
+  const handler = new FastCGIHandler(options);
+
+  const handleData = createCGIParser(
+    req,
+    res,
+    handler,
+    defaultHeaders,
+    `GreenRhombus/${modInfo.version}`
+  );
+
+  handler.on("error", (error) => {
+    if (handler.headersParsed) return; // Don't call res.writeHead multiple times
+    const errorCode = ["ENOTFOUND", "EHOSTUNREACH", "ECONNREFUSED"].includes(
+      error.code
+    )
+      ? 503
+      : error.code === "EMFILE"
+        ? 429
+        : 500;
+    res.error(errorCode, `GreenRhombus/${modInfo.version}`, error);
+  });
+
+  res.prependListener("close", () => {
+    if (handler.stdout) handler.stdout.unpipe(res);
+  });
+
+  res.on("error", () => {}); // Suppress response stream errors
+
+  const handleConnection = () => {
+    handler.stdout.on("data", handleData);
+    handler.stderr.on("data", (data) => {
+      errorBuffer += data.toString();
+    });
+    handler.init();
+    req.pipe(handler.stdin);
+
+    handler.on("exit", (exitCode, signal) => {
+      if (!handler.headersParsed && (signal || exitCode !== 0)) {
+        const error = new Error(
+          `Process execution failed!${errorBuffer ? ` Reason: ${errorBuffer.trim()}` : ""}`
+        );
+        res.error(500, `GreenRhombus/${modInfo.version}`, error);
+      } else if (errorBuffer.trim()) {
+        logFacilities.errmessage("There were FastCGI application errors:");
+        logFacilities.errmessage(errorBuffer.trim());
+      }
+
+      handler.stdout.removeListener("data", handleData);
+      handler.stdout.unpipe(res);
+      if (!res.finished) res.end();
+    });
+  };
+
+  if (handler.socket.connecting === undefined || handler.socket.connecting) {
+    handler.on("connect", handleConnection);
+  } else if (!handler.socket.destroyed) {
+    handleConnection();
+  }
+};
+
+function executeFastCGIWithEnv(
+  scriptPath,
+  pathInfo,
+  req,
+  res,
+  logFacilities,
+  serverSoftware,
+  defaultHeaders,
+  fastCGIConfig,
+  wwwroot,
+  svrjsConfig
+) {
+  // Function to set up environment variables and execute FastCGI scripts
+  const environmentVariables = {};
+
+  // Authentication details
+  if (req.authUser) {
+    if (req.headers.authorization) {
+      environmentVariables.AUTH_TYPE = req.headers.authorization.split(" ")[0];
+    }
+    environmentVariables.REMOTE_USER = req.authUser;
+  }
+
+  // Query string
+  const queryString = req.url.split("?")[1] || "";
+  environmentVariables.QUERY_STRING = queryString;
+
+  // Server details
+  environmentVariables.SERVER_SOFTWARE = serverSoftware;
+  environmentVariables.SERVER_PROTOCOL = `HTTP/${req.httpVersion}`;
+
+  if (req.socket.localAddress && req.socket.localPort) {
+    environmentVariables.SERVER_PORT = req.socket.localPort;
+    let localAddress = req.socket.localAddress.replace(/^::ffff:/i, "");
+    if (localAddress.includes(":")) {
+      localAddress = `[${localAddress}]`;
+    }
+    environmentVariables.SERVER_ADDR = localAddress;
+  }
+
+  if (
+    svrjsConfig.serverAdministratorEmail &&
+    svrjsConfig.serverAdministratorEmail !== "[no contact information]"
+  ) {
+    environmentVariables.SERVER_ADMIN = svrjsConfig.serverAdministratorEmail;
+  }
+
+  environmentVariables.SERVER_NAME = req.headers.host;
+  environmentVariables.DOCUMENT_ROOT = wwwroot;
+
+  // Script details
+  const platform = os.platform();
+  const normalizePath = (path) =>
+    platform === "win32" ? path.replace(/\//g, "\\") : path;
+
+  environmentVariables.SCRIPT_NAME = scriptPath;
+  environmentVariables.SCRIPT_FILENAME = normalizePath(
+    `${wwwroot}${scriptPath}`
+  )
+    .replace(/\\+/g, "\\")
+    .replace(/\/\/+/, "/");
+  environmentVariables.PATH_INFO = decodeURIComponent(pathInfo);
+  environmentVariables.PATH_TRANSLATED = pathInfo
+    ? normalizePath(`${wwwroot}${decodeURIComponent(pathInfo)}`)
+    : "";
+
+  // Request details
+  environmentVariables.REQUEST_METHOD = req.method;
+  environmentVariables.REQUEST_URI =
+    req.originalParsedURL &&
+    req.parsedURL &&
+    req.originalParsedURL.pathname === req.parsedURL.pathname
+      ? req.url
+      : `${req.originalParsedURL.pathname}${req.parsedURL.search ? `?${req.parsedURL.search}` : ""}`;
+
+  const remoteAddress =
+    req.socket.realRemoteAddress ||
+    (svrjsConfig.enableIPSpoofing &&
+      req.headers["x-forwarded-for"] &&
+      req.headers["x-forwarded-for"].split(",")[0].trim()) ||
+    req.socket.remoteAddress;
+
+  environmentVariables.REMOTE_ADDR = remoteAddress.replace(/^::ffff:/i, "");
+  environmentVariables.REMOTE_PORT =
+    req.socket.realRemotePort || req.socket.remotePort;
+
+  if (req.socket.encrypted) {
+    environmentVariables.HTTPS = "ON";
+  }
+
+  // Content headers
+  if (req.headers["content-type"]) {
+    environmentVariables.CONTENT_TYPE = req.headers["content-type"];
+  }
+
+  environmentVariables.CONTENT_LENGTH = req.headers["content-length"] || "0";
+
+  // HTTP headers
+  const headersCopy = Object.assign({}, req.headers);
+  delete headersCopy["content-type"];
+  delete headersCopy["content-length"];
+
+  Object.keys(headersCopy).forEach((key) => {
+    const normalizedKey = key.replace(/[^0-9A-Za-z]+/g, "_").toUpperCase();
+    environmentVariables[`HTTP_${normalizedKey}`] = headersCopy[key];
+  });
+
+  executeFastCGI(
+    req,
+    res,
+    logFacilities,
+    defaultHeaders,
+    environmentVariables,
+    fastCGIConfig
+  );
+}
+
+const normalizedWebrootSupported =
+  process.versions.svrjs &&
+  process.versions.svrjs.match(
+    /^(?:Nightly-|(?:[5-9]|[1234][0-9])[0-9]*\.|4\.(?:(?:[1][0-9]|[2-9])+\.))/i
+  );
+
+// Exported SVR.JS mod callback
+module.exports = (req, res, logFacilities, config, next) => {
+  let scriptExts = config.fastCGIScriptExtensions
+    ? config.fastCGIScriptExtensions
+    : scriptExtsFromSeparateFile;
+  let fastCGIConfig = config.fastCGIConfiguration
+    ? config.fastCGIConfiguration
+    : fastcgiConfigFromSeparateFile;
+  const detectedWwwroot = normalizedWebrootSupported
+    ? config.wwwroot
+    : process.cwd();
+
+  let ext = req.parsedURL.pathname.match(/[^/]\.([^.]+)$/);
+  if (!ext) ext = "";
+  else ext = ext[1].toLowerCase();
+
+  const isScriptExt = scriptExts.indexOf("." + ext) != -1;
+
+  let preparedFastCGIConfig = {};
+  if (fastCGIConfig.multiConfig) {
+    const hostnames = Object.keys(fastCGIConfig.multiConfig);
+    for (let i = 0; i < hostnames.length; i++) {
+      if (hostnames[i] == "*") {
+        preparedFastCGIConfig = Object.assign(
+          {},
+          fastCGIConfig.multiConfig["*"]
+        );
+        break;
+      } else if (
+        req.headers.host &&
+        hostnames[i].indexOf("*.") == 0 &&
+        hostnames[i] != "*."
+      ) {
+        const hostnamesRoot = hostnames[i].substring(2);
+        if (
+          req.headers.host == hostnamesRoot ||
+          (req.headers.host.length > hostnamesRoot.length &&
+            req.headers.host.indexOf("." + hostnamesRoot) ==
+              req.headers.host.length - hostnamesRoot.length - 1)
+        ) {
+          preparedFastCGIConfig = Object.assign(
+            {},
+            fastCGIConfig.multiConfig[hostnames[i]]
+          );
+          break;
+        }
+      } else if (req.headers.host && req.headers.host == hostnames[i]) {
+        preparedFastCGIConfig = Object.assign(
+          {},
+          fastCGIConfig.multiConfig[hostnames[i]]
+        );
+        break;
+      }
+    }
+  } else {
+    preparedFastCGIConfig = Object.assign({}, fastCGIConfig);
+    delete preparedFastCGIConfig.multiConfig;
+  }
+
+  if (preparedFastCGIConfig.path !== undefined)
+    preparedFastCGIConfig.path = preparedFastCGIConfig.path.replace(
+      /([^/])\/+$/,
+      "$1"
+    );
+  if (preparedFastCGIConfig.socketPath === undefined) {
+    if (preparedFastCGIConfig.host === undefined)
+      preparedFastCGIConfig.host = "localhost";
+    if (preparedFastCGIConfig.port === undefined)
+      preparedFastCGIConfig.port = 4000;
+  }
+
+  if (
+    preparedFastCGIConfig.path !== undefined &&
+    (req.parsedURL.pathname == preparedFastCGIConfig.path ||
+      req.parsedURL.pathname.indexOf(preparedFastCGIConfig.path + "/") == 0)
+  ) {
+    try {
+      executeFastCGIWithEnv(
+        decodeURIComponent(req.parsedURL.pathname),
+        req.parsedURL.pathname.replace(preparedFastCGIConfig.path, ""),
+        req,
+        res,
+        logFacilities,
+        config.getCustomHeaders()["Server"] +
+          (config.exposeModsInErrorPages ||
+          config.exposeModsInErrorPages === undefined
+            ? " GreenRhombus/" + modInfo.version
+            : ""),
+        config.getCustomHeaders(),
+        preparedFastCGIConfig,
+        detectedWwwroot,
+        config
+      );
+    } catch (ex) {
+      res.error(500, `GreenRhombus/${modInfo.version}`, ex);
+    }
+  } else if (
+    ((req.parsedURL.pathname == "/greenrhombus-config.json" ||
+      (os.platform() == "win32" &&
+        req.parsedURL.pathname.toLowerCase() == "/greenrhombus-config.json")) &&
+      path.normalize(__dirname + "/../../..") == detectedWwwroot) ||
+    ((req.parsedURL.pathname == "/greenrhombus-scriptexts.json" ||
+      (os.platform() == "win32" &&
+        req.parsedURL.pathname.toLowerCase() ==
+          "/greenrhombus-scriptexts.json")) &&
+      path.normalize(__dirname + "/../../..") == detectedWwwroot)
+  ) {
+    res.error(403, `GreenRhombus/${modInfo.version}`);
+  } else {
+    fs.stat(
+      detectedWwwroot + decodeURIComponent(req.parsedURL.pathname),
+      (err, stats) => {
+        if (!err) {
+          if (!stats.isFile()) {
+            if (scriptExts.indexOf(".php") != -1) {
+              fs.stat(
+                detectedWwwroot +
+                  decodeURIComponent(req.parsedURL.pathname) +
+                  "/index.php",
+                (e2, s2) => {
+                  if (!e2 && s2.isFile()) {
+                    try {
+                      executeFastCGIWithEnv(
+                        (
+                          decodeURIComponent(req.parsedURL.pathname) +
+                          "/index.php"
+                        ).replace(/\/+/g, "/"),
+                        "",
+                        req,
+                        res,
+                        logFacilities,
+                        config.getCustomHeaders()["Server"] +
+                          (config.exposeModsInErrorPages ||
+                          config.exposeModsInErrorPages === undefined
+                            ? " GreenRhombus/" + modInfo.version
+                            : ""),
+                        config.getCustomHeaders(),
+                        preparedFastCGIConfig,
+                        detectedWwwroot,
+                        config
+                      );
+                    } catch (ex) {
+                      res.error(500, `GreenRhombus/${modInfo.version}`, ex);
+                    }
+                  } else {
+                    next();
+                  }
+                }
+              );
+            } else if (scriptExts.indexOf(".cgi") != -1) {
+              fs.stat(
+                detectedWwwroot +
+                  decodeURIComponent(req.parsedURL.pathname) +
+                  "/index.cgi",
+                (e3, s3) => {
+                  if (!e3 && s3.isFile()) {
+                    try {
+                      executeFastCGIWithEnv(
+                        (
+                          decodeURIComponent(req.parsedURL.pathname) +
+                          "/index.cgi"
+                        ).replace(/\/+/g, "/"),
+                        "",
+                        req,
+                        res,
+                        logFacilities,
+                        config.getCustomHeaders()["Server"] +
+                          (config.exposeModsInErrorPages ||
+                          config.exposeModsInErrorPages === undefined
+                            ? " GreenRhombus/" + modInfo.version
+                            : ""),
+                        config.getCustomHeaders(),
+                        preparedFastCGIConfig,
+                        detectedWwwroot,
+                        config
+                      );
+                    } catch (ex) {
+                      res.error(500, `GreenRhombus/${modInfo.version}`, ex);
+                    }
+                  } else {
+                    next();
+                  }
+                }
+              );
+            } else {
+              next();
+            }
+          } else {
+            if (isScriptExt) {
+              try {
+                executeFastCGIWithEnv(
+                  decodeURIComponent(req.parsedURL.pathname),
+                  "",
+                  req,
+                  res,
+                  logFacilities,
+                  config.getCustomHeaders()["Server"] +
+                    (config.exposeModsInErrorPages ||
+                    config.exposeModsInErrorPages === undefined
+                      ? " GreenRhombus/" + modInfo.version
+                      : ""),
+                  config.getCustomHeaders(),
+                  preparedFastCGIConfig,
+                  detectedWwwroot,
+                  config
+                );
+              } catch (ex) {
+                res.error(500, `GreenRhombus/${modInfo.version}`, ex);
+              }
+            } else {
+              next();
+            }
+          }
+        } else if (err && err.code == "ENOTDIR") {
+          const checkPath = (pth, cb, a) => {
+            // Function to check the path of the file and connect to the FastCGI server
+            const cpth = pth.split("/");
+            if (cpth.length < 2) {
+              cb(false);
+              return;
+            }
+            let b = [];
+            if (a) b = a.split("/");
+            fs.stat(detectedWwwroot + "/" + pth, function (err, stats) {
+              if (!err && stats.isFile()) {
+                cb({
+                  scriptPath: pth,
+                  pathInfo: a !== undefined ? "/" + a : ""
+                });
+              } else {
+                b.unshift(cpth.pop());
+                return checkPath(cpth.join("/"), cb, b.join("/"));
+              }
+            });
+          };
+          checkPath(
+            "." + decodeURIComponent(req.parsedURL.pathname),
+            function (pathp) {
+              if (!pathp) {
+                next();
+              } else {
+                let newext = pathp.scriptPath.match(/[^/]\.([^.]+)$/);
+                if (!newext) newext = "";
+                else newext = newext[1].toLowerCase();
+                if (scriptExts.indexOf(newext) != -1) {
+                  try {
+                    executeFastCGIWithEnv(
+                      pathp.scriptPath.substring(1),
+                      pathp.pathInfo,
+                      req,
+                      res,
+                      logFacilities,
+                      config.getCustomHeaders()["Server"] +
+                        (config.exposeModsInErrorPages ||
+                        config.exposeModsInErrorPages === undefined
+                          ? " GreenRhombus/" + modInfo.version
+                          : ""),
+                      config.getCustomHeaders(),
+                      preparedFastCGIConfig,
+                      detectedWwwroot,
+                      config
+                    );
+                  } catch (ex) {
+                    res.error(500, `GreenRhombus/${modInfo.version}`, ex);
+                  }
+                } else {
+                  next();
+                }
+              }
+            }
+          );
+        } else {
+          next(); //Invoke default error handler
+        }
+      }
+    );
+  }
+};
+
+module.exports.configValidators = {
+  fastCGIConfiguration: (value) =>
+    typeof value === "object" &&
+    value !== null &&
+    (value.path === undefined || typeof value.path === "string") &&
+    (value.socketPath === undefined || typeof value.socketPath === "string") &&
+    (value.host === undefined || typeof value.host === "string") &&
+    (value.port === undefined ||
+      (typeof value.port === "number" &&
+        value.port >= 0 &&
+        value.port <= 65535)) &&
+    (value.multiConfig === undefined ||
+      (typeof value.multiConfig === "object" &&
+        value.multiConfig !== null &&
+        Object.keys(value.multiConfig).every((host) => {
+          const hostValue = value.multiConfig[host];
+          return (
+            (hostValue.path === undefined ||
+              typeof hostValue.path === "string") &&
+            (hostValue.socketPath === undefined ||
+              typeof hostValue.socketPath === "string") &&
+            (hostValue.host === undefined ||
+              typeof hostValue.host === "string") &&
+            (hostValue.port === undefined ||
+              (typeof hostValue.port === "number" &&
+                hostValue.port >= 0 &&
+                hostValue.port <= 65535))
+          );
+        }))),
+
+  fastCGIScriptExtensions: (value) =>
+    Array.isArray(value) && value.every((ext) => typeof ext === "string")
+};
+
+module.exports.modInfo = modInfo;

src/utils/cgiParser.js

@@ -0,0 +1,101 @@
+function createCGIParser(req, res, handler, defaultHeaders, software) {
+  let responseBuffer = "";
+  let headerEndIndex = -1;
+
+  const dataHandler = (data) => {
+    if (!dataHandler.headersParsed) {
+      responseBuffer += data.toString("latin1");
+      const headerMatch = responseBuffer.match(
+        /(?:\r\n\r\n|\n\r\n\r|\n\n|\r\r)/
+      );
+
+      if (headerMatch) {
+        dataHandler.headersParsed = true;
+        const endOfHeaders = headerMatch[0];
+        headerEndIndex = headerMatch.index;
+
+        const rawHeaders = responseBuffer
+          .substring(0, headerEndIndex)
+          .split(/(?:\r\n|\n\r|\n|\r)/);
+
+        let parsedHeaders = defaultHeaders || {};
+        let statusCode = 200;
+        let statusMessage = "OK";
+
+        if (rawHeaders[0].match(/^HTTP\//)) {
+          // eslint-disable-next-line no-unused-vars
+          const [ignore, code, message] =
+            rawHeaders.shift().match(/^[^ ]+ *([0-9]{3}) *(.*)/) || [];
+          if (code) {
+            statusCode = parseInt(code);
+            statusMessage = message;
+          }
+        } else if (rawHeaders[0].indexOf(":") === -1) {
+          // eslint-disable-next-line no-unused-vars
+          const [ignore, code, message] =
+            rawHeaders.shift().match(/^([0-9]{3}) *(.*)/) || [];
+          if (code) {
+            statusCode = parseInt(code);
+            statusMessage = message;
+          }
+        }
+
+        let hasLocationHeader = false;
+
+        rawHeaders.forEach((headerLine) => {
+          // eslint-disable-next-line no-unused-vars
+          const [ignore, name, value] =
+            headerLine.match(/^([^:]+): *(.*)/) || [];
+
+          if (name) {
+            if (name.toLowerCase() === "status") {
+              // eslint-disable-next-line no-unused-vars
+              const [ignore, code, message] =
+                value.match(/^([0-9]{3}) *(.*)/) || [];
+              if (code) {
+                statusCode = parseInt(code);
+                statusMessage = message;
+              }
+            } else if (name.toLowerCase() === "set-cookie") {
+              parsedHeaders["Set-Cookie"] = parsedHeaders["Set-Cookie"] || [];
+              parsedHeaders["Set-Cookie"].push(value);
+            } else {
+              if (name.toLowerCase() === "location") hasLocationHeader = true;
+              parsedHeaders[name] = value;
+            }
+          }
+        });
+
+        if ((statusCode < 300 || statusCode > 399) && hasLocationHeader) {
+          statusCode = 302;
+          statusMessage = "Found";
+        }
+
+        try {
+          res.writeHead(statusCode, statusMessage, parsedHeaders);
+          res.write(
+            Buffer.from(
+              responseBuffer.substring(headerEndIndex + endOfHeaders.length),
+              "latin1"
+            )
+          );
+        } catch (error) {
+          handler.removeAllListeners("exit");
+          handler.stdout.removeAllListeners("data");
+          res.error(500, software, error);
+          return;
+        }
+      }
+    } else if (!res.finished) {
+      res.write(data);
+      handler.stdout.removeListener("data", dataHandler);
+      handler.stdout.pipe(res, { end: false });
+    }
+  };
+
+  dataHandler.headersParsed = false;
+
+  return dataHandler;
+}
+
+module.exports = createCGIParser;

src/utils/fastCgi.js

@@ -0,0 +1,370 @@
+const EventEmitter = require("events");
+const stream = require("stream");
+const net = require("net");
+
+const constants = {
+  BEGIN_REQUEST: 1,
+  ABORT_REQUEST: 2,
+  END_REQUEST: 3,
+  PARAMS: 4,
+  STDIN: 5,
+  STDOUT: 6,
+  STDERR: 7,
+  DATA: 8,
+  GET_VALUES: 9,
+  GET_VALUES_RESULT: 10,
+  UNKNOWN_TYPE: 11,
+  RESPONDER: 1,
+  REQUEST_COMPLETE: 0,
+  CANT_MPX_CONN: 1,
+  OVERLOADED: 2,
+  UNKNOWN_ROLE: 3
+};
+
+function buildFastCGIPacket(type, requestID, content) {
+  const packet = Buffer.alloc(content.length + (content.length % 8) + 8);
+  packet.writeUInt8(1, 0); // version
+  packet.writeUInt8(type, 1); // type
+  packet.writeUInt16BE(requestID, 2); // requestId
+  packet.writeUInt16BE(content.length, 4); // contentLength
+  packet.writeUInt8(content.length % 8, 6); // paddingLength
+  packet.writeUInt8(0, 7); // reserved
+  Buffer.from(content).copy(packet, 8); // content
+  return packet;
+}
+
+function buildNameValuePair(name, value) {
+  if (typeof name == "undefined" || typeof value == "undefined")
+    return Buffer.alloc(0);
+  name = String(name);
+  value = String(value);
+  const nameLength = name.length;
+  const valueLength = value.length;
+  const nameLengthBytes = nameLength > 127 ? 4 : 1;
+  const valueLengthBytes = valueLength > 127 ? 4 : 1;
+  const pair = Buffer.alloc(
+    nameLength + valueLength + nameLengthBytes + valueLengthBytes
+  );
+
+  // nameLength
+  if (nameLengthBytes == 4) {
+    pair.writeUInt32BE(Math.min(0xffffffff, 0x80000000 + nameLength), 0);
+  } else {
+    pair.writeUInt8(nameLength, 0);
+  }
+
+  // valueLength
+  if (valueLengthBytes == 4) {
+    pair.writeUInt32BE(
+      Math.min(0xffffffff, 0x80000000 + valueLength),
+      nameLengthBytes
+    );
+  } else {
+    pair.writeUInt8(valueLength, nameLengthBytes);
+  }
+
+  Buffer.from(name).copy(pair, nameLengthBytes + valueLengthBytes); // nameData
+  Buffer.from(value).copy(
+    pair,
+    nameLengthBytes + valueLengthBytes + nameLength
+  ); // valueData
+
+  return pair;
+}
+
+function writeFastCGIPacket(socket, type, requestID, content) {
+  if (content.length != 0) {
+    const contentSlices = Math.ceil(content.length / 65535);
+    let chunk = Buffer.alloc(0);
+    for (let i = 0; i < contentSlices; i++) {
+      let chunkOffset = 65536 * i;
+      const chunkSize = Math.min(65535, content.length - chunkOffset);
+      chunk = Buffer.alloc(chunkSize);
+      content.copy(chunk, 0, chunkOffset, chunkOffset + chunkSize);
+      socket.write(buildFastCGIPacket(type, requestID, chunk));
+    }
+  } else {
+    socket.write(buildFastCGIPacket(type, requestID, Buffer.alloc(0)));
+  }
+}
+
+function parseFastCGIPacket(packet) {
+  return {
+    fcgiVersion: packet.readUInt8(0), // version
+    type: packet.readUInt8(1), // type
+    requestID: packet.readUInt16BE(2), // requestId
+    content: packet.subarray(8, 8 + packet.readUInt16BE(4)) // contentLength
+  };
+}
+
+function FastCGIHandler(options) {
+  let requestID = options.requestID;
+  if (!requestID) requestID = 1;
+
+  const fastCGISocketHandler = (chunk) => {
+    let chunkIndex = 0;
+
+    while (
+      chunkIndex < chunk.length ||
+      (headerIndex == 8 && bodyIndex == packetBody.length && paddingLength == 0)
+    ) {
+      if (headerIndex < 8) {
+        chunk.copy(
+          packetHeader,
+          headerIndex,
+          chunkIndex,
+          Math.min(chunk.length, chunkIndex + 8 - headerIndex)
+        );
+        const ic = Math.min(chunk.length - chunkIndex, 8 - headerIndex);
+        headerIndex += ic;
+        chunkIndex += ic;
+        if (headerIndex == 8) {
+          packetBody = Buffer.alloc(packetHeader.readUInt16BE(4));
+          paddingLength = packetHeader.readUInt8(6);
+        }
+      } else if (headerIndex == 8 && bodyIndex < packetBody.length) {
+        chunk.copy(
+          packetBody,
+          bodyIndex,
+          chunkIndex,
+          Math.min(chunk.length, chunkIndex + packetBody.length - bodyIndex)
+        );
+        const ic = Math.min(
+          chunk.length - chunkIndex,
+          packetBody.length - bodyIndex
+        );
+        bodyIndex += ic;
+        chunkIndex += ic;
+      } else if (
+        headerIndex == 8 &&
+        bodyIndex == packetBody.length &&
+        paddingIndex <= paddingLength
+      ) {
+        const ic = Math.min(
+          chunk.length - chunkIndex,
+          paddingLength - paddingIndex
+        );
+        paddingIndex += ic;
+        chunkIndex += ic;
+        if (paddingIndex == paddingLength) {
+          headerIndex = 0;
+          bodyIndex = 0;
+          paddingIndex = 0;
+          const packet = Buffer.alloc(8 + packetBody.length + paddingLength);
+          packetHeader.copy(packet);
+          packetBody.copy(packet, 8);
+          processFastCGIPacket(packet);
+        }
+      }
+    }
+  };
+
+  let processFastCGIPacket = (packet) => {
+    const processedPacket = parseFastCGIPacket(packet);
+    if (processedPacket.requestID != requestID) return; // Drop the packet
+    if (processedPacket.type == constants.STDOUT) {
+      try {
+        if (processedPacket.content.length > 0)
+          stdoutPush(processedPacket.content);
+        // eslint-disable-next-line no-unused-vars
+      } catch (err) {
+        // STDOUT will be lost instead of crashing the server
+      }
+    } else if (processedPacket.type == constants.STDERR) {
+      try {
+        if (processedPacket.content.length > 0)
+          emulatedStderr.push(processedPacket.content);
+        // eslint-disable-next-line no-unused-vars
+      } catch (err) {
+        // STDERR will be lost anyway...
+      }
+    } else if (
+      processedPacket.type == constants.END_REQUEST &&
+      processedPacket.content.length > 5
+    ) {
+      if (typeof socket !== "undefined") {
+        socket.removeListener("data", fastCGISocketHandler);
+        socket.removeAllListeners("error");
+        socket.addListener("error", () => {});
+        processFastCGIPacket = function () {};
+        try {
+          socket.end(); // Fixes connection not closing properly in Bun
+          // eslint-disable-next-line no-unused-vars
+        } catch (err) {
+          // It is already closed
+        }
+      }
+      const appStatus = processedPacket.content.readUInt32BE(0);
+      const protocolStatus = processedPacket.content.readUInt8(4);
+      if (protocolStatus != constants.REQUEST_COMPLETE) {
+        let err = new Error("Unknown error");
+        if (protocolStatus == constants.OVERLOADED) {
+          err = new Error("FastCGI server overloaded");
+          err.code = "EMFILE";
+          err.errno = 24;
+        } else if (protocolStatus == constants.UNKNOWN_ROLE) {
+          err = new Error("Role not supported by the FastCGI application");
+        } else if (protocolStatus == constants.CANT_MPX_CONN) {
+          err = new Error(
+            "Multiplexed connections not supported by the FastCGI application"
+          );
+        }
+        stdoutPush(null);
+        if (
+          emulatedStdout._readableState &&
+          emulatedStdout._readableState.flowing !== null &&
+          !emulatedStdout.endEmitted
+        ) {
+          emulatedStdout.on("end", function () {
+            emulatedStderr.push(null);
+            eventEmitter.emit("error", err);
+          });
+        } else {
+          emulatedStderr.push(null);
+          eventEmitter.emit("error", err);
+        }
+      } else {
+        stdoutPush(null);
+        if (
+          emulatedStdout._readableState &&
+          emulatedStdout._readableState.flowing !== null &&
+          !emulatedStdout.endEmitted
+        ) {
+          emulatedStdout.on("end", function () {
+            emulatedStderr.push(null);
+            eventEmitter.emit("exit", appStatus, null);
+          });
+        } else {
+          emulatedStderr.push(null);
+          eventEmitter.emit("exit", appStatus, null);
+        }
+      }
+    }
+  };
+
+  const eventEmitter = new EventEmitter();
+  let packetHeader = Buffer.alloc(8);
+  let packetBody = Buffer.alloc(0);
+  let paddingLength = 0;
+  let headerIndex = 0;
+  let bodyIndex = 0;
+  let paddingIndex = 0;
+
+  const emulatedStdin = new stream.Writable({
+    write: function (chunk, encoding, callback) {
+      try {
+        if (chunk.length != 0) {
+          writeFastCGIPacket(socket, constants.STDIN, requestID, chunk);
+        }
+        callback(null);
+      } catch (err) {
+        callback(err);
+      }
+    },
+    final: function (callback) {
+      try {
+        writeFastCGIPacket(socket, constants.STDIN, requestID, Buffer.alloc(0));
+        // eslint-disable-next-line no-unused-vars
+      } catch (err) {
+        // writing failed
+      }
+      callback();
+    }
+  });
+
+  function stdoutPush(data) {
+    if (data === null) {
+      stdoutToEnd = true;
+    } else {
+      stdoutBuffer = Buffer.concat([stdoutBuffer, Buffer.from(data)]);
+    }
+    for (let i = 0; i < hp.length; i++) {
+      const func = hp.shift();
+      if (func) func();
+    }
+    emulatedStdout.resume();
+  }
+
+  let stdoutBuffer = Buffer.alloc(0);
+  let stdoutToEnd = false;
+  const hp = [];
+  const emulatedStdout = new stream.Readable({
+    read: (n) => {
+      const s = emulatedStdout;
+      const handler = () => {
+        if (stdoutBuffer.length == 0) {
+          if (!stdoutToEnd) {
+            hp.push(handler);
+            s.pause();
+          } else {
+            s.push(null);
+          }
+        } else {
+          const bytesToPush = Math.min(stdoutBuffer.length, n);
+          const bufferToPush = stdoutBuffer.subarray(0, bytesToPush);
+          stdoutBuffer = stdoutBuffer.subarray(bytesToPush);
+          s.push(bufferToPush);
+        }
+      };
+      if (n != 0) handler();
+    }
+  });
+  emulatedStdout.pause(); // Reduce backpressure
+
+  const emulatedStderr = new stream.Readable({
+    read: function () {}
+  });
+
+  const init = () => {
+    // Begin the request
+    const beginPacket = Buffer.alloc(8);
+    beginPacket.writeUInt16BE(constants.RESPONDER, 0); // FastCGI responder
+    beginPacket.writeUInt8(0, 2); // Don't keep alive
+    writeFastCGIPacket(socket, constants.BEGIN_REQUEST, requestID, beginPacket);
+
+    // Environment variables
+    let envPacket = Buffer.alloc(0);
+    Object.keys(options.env).forEach((key) => {
+      envPacket = Buffer.concat([
+        envPacket,
+        buildNameValuePair(key, options.env[key])
+      ]);
+    });
+    if (envPacket.length > 0)
+      writeFastCGIPacket(socket, constants.PARAMS, requestID, envPacket);
+    writeFastCGIPacket(socket, constants.PARAMS, requestID, Buffer.alloc(0));
+  };
+
+  eventEmitter.stdin = emulatedStdin;
+  eventEmitter.stdout = emulatedStdout;
+  eventEmitter.stderr = emulatedStderr;
+  eventEmitter.init = init;
+
+  // Create socket
+  const socket = net
+    .createConnection(options, () => {
+      eventEmitter.emit("connect");
+    })
+    .on("error", (err) => {
+      stdoutPush(null);
+      emulatedStderr.push(null);
+      eventEmitter.removeAllListeners("exit");
+      eventEmitter.emit("error", err);
+    })
+    .on("data", fastCGISocketHandler);
+
+  eventEmitter.socket = socket;
+
+  eventEmitter.requestID = requestID;
+
+  return eventEmitter;
+}
+
+module.exports = {
+  FastCGIHandler: FastCGIHandler,
+  constants: constants,
+  buildFastCGIPacket: buildFastCGIPacket,
+  buildNameValuePair: buildNameValuePair,
+  writeFastCGIPacket: writeFastCGIPacket,
+  parseFastCGIPacket: parseFastCGIPacket
+};

tests/utils/cgiParser.test.js

@@ -0,0 +1,130 @@
+const createCGIParser = require("../../src/utils/cgiParser.js");
+
+jest.mock("http"); // Mocking HTTP to simulate the response behavior
+
+describe("createCGIParser", () => {
+  let req, res, handler, defaultHeaders, software, dataHandler;
+
+  beforeEach(() => {
+    req = {};
+    res = {
+      writeHead: jest.fn(),
+      write: jest.fn(),
+      finished: false,
+      error: jest.fn()
+    };
+    handler = {
+      stdout: {
+        removeAllListeners: jest.fn(),
+        pipe: jest.fn(),
+        on: jest.fn()
+      },
+      removeAllListeners: jest.fn()
+    };
+    defaultHeaders = { "X-Test-Header": "TestValue" };
+    software = "TestSoftware";
+  });
+
+  test("should parse headers and write response correctly", () => {
+    const inputHeaders =
+      "Status: 200 OK\r\nContent-Type: text/plain\r\nContent-Length: 13\r\n\r\nHello, world!";
+    const buffer = Buffer.from(inputHeaders, "latin1");
+
+    dataHandler = createCGIParser(req, res, handler, defaultHeaders, software);
+    dataHandler(buffer);
+
+    expect(res.writeHead).toHaveBeenCalledWith(200, "OK", {
+      "Content-Type": "text/plain",
+      "Content-Length": "13",
+      "X-Test-Header": "TestValue"
+    });
+    expect(res.write).toHaveBeenCalledWith(
+      Buffer.from("Hello, world!", "latin1")
+    );
+  });
+
+  test("should handle status headers without protocol", () => {
+    const inputHeaders =
+      "Status: 200 OK\r\nContent-Type: text/html\r\n\r\n<body>Success</body>";
+    const buffer = Buffer.from(inputHeaders, "latin1");
+
+    dataHandler = createCGIParser(req, res, handler, defaultHeaders, software);
+    dataHandler(buffer);
+
+    expect(res.writeHead).toHaveBeenCalledWith(200, "OK", {
+      "Content-Type": "text/html",
+      "X-Test-Header": "TestValue"
+    });
+    expect(res.write).toHaveBeenCalledWith(
+      Buffer.from("<body>Success</body>", "latin1")
+    );
+  });
+
+  test("should handle malformed status line", () => {
+    const inputHeaders =
+      "Content-Type: text/plain\r\n\r\nMalformed status line.";
+    const buffer = Buffer.from(inputHeaders, "latin1");
+
+    dataHandler = createCGIParser(req, res, handler, defaultHeaders, software);
+    dataHandler(buffer);
+
+    expect(res.writeHead).toHaveBeenCalledWith(200, "OK", {
+      "Content-Type": "text/plain",
+      "X-Test-Header": "TestValue"
+    });
+    expect(res.write).toHaveBeenCalledWith(
+      Buffer.from("Malformed status line.", "latin1")
+    );
+  });
+
+  test("should handle redirection logic for Location header", () => {
+    const inputHeaders = "Status: 302 Found\r\nLocation: /new-location\r\n\r\n";
+    const buffer = Buffer.from(inputHeaders, "latin1");
+
+    dataHandler = createCGIParser(req, res, handler, defaultHeaders, software);
+    dataHandler(buffer);
+
+    expect(res.writeHead).toHaveBeenCalledWith(302, "Found", {
+      Location: "/new-location",
+      "X-Test-Header": "TestValue"
+    });
+    expect(res.write).toHaveBeenCalledWith(Buffer.from("", "latin1"));
+  });
+
+  test("should handle Set-Cookie headers correctly", () => {
+    const inputHeaders =
+      "Status: 200 OK\r\nSet-Cookie: sessionId=abc123; HttpOnly\r\nSet-Cookie: theme=dark; Secure\r\n\r\nBody content";
+    const buffer = Buffer.from(inputHeaders, "latin1");
+
+    dataHandler = createCGIParser(req, res, handler, defaultHeaders, software);
+    dataHandler(buffer);
+
+    expect(res.writeHead).toHaveBeenCalledWith(200, "OK", {
+      "Set-Cookie": ["sessionId=abc123; HttpOnly", "theme=dark; Secure"],
+      "X-Test-Header": "TestValue"
+    });
+    expect(res.write).toHaveBeenCalledWith(
+      Buffer.from("Body content", "latin1")
+    );
+  });
+
+  test("should call res.error on failure to writeHead or write", () => {
+    res.writeHead.mockImplementation(() => {
+      throw new Error("writeHead error");
+    });
+    const inputHeaders =
+      "Status: 500 Internal Server Error\r\n\r\nError occurred.";
+    const buffer = Buffer.from(inputHeaders, "latin1");
+
+    dataHandler = createCGIParser(req, res, handler, defaultHeaders, software);
+    dataHandler(buffer);
+
+    expect(res.error).toHaveBeenCalledWith(
+      500,
+      "TestSoftware",
+      expect.any(Error)
+    );
+    expect(handler.removeAllListeners).toHaveBeenCalled();
+    expect(handler.stdout.removeAllListeners).toHaveBeenCalled();
+  });
+});

tests/utils/fastCgi.test.js

@@ -0,0 +1,150 @@
+const {
+  FastCGIHandler,
+  constants,
+  buildFastCGIPacket,
+  buildNameValuePair,
+  writeFastCGIPacket
+} = require("../../src/utils/fastCgi.js");
+const net = require("net");
+const EventEmitter = require("events");
+
+jest.mock("net");
+
+describe("FastCGI module", () => {
+  let mockSocket;
+
+  beforeEach(() => {
+    mockSocket = {
+      write: jest.fn(),
+      on: jest.fn().mockImplementation((event, handler) => {
+        if (event === "data") {
+          mockSocket.dataHandler = handler;
+        }
+        return mockSocket; // Enable method chaining
+      }),
+      removeListener: jest.fn().mockImplementation((event, handler) => {
+        if (event === "data" && mockSocket.dataHandler == handler) {
+          mockSocket.dataHandler = () => {};
+        }
+        return mockSocket; // Enable method chaining
+      }),
+      dataHandler: () => {}
+    };
+
+    net.createConnection.mockReturnValue(mockSocket);
+  });
+
+  afterEach(() => {
+    jest.clearAllMocks();
+  });
+
+  test("should create a socket and connect", () => {
+    const handler = new FastCGIHandler({ host: "localhost", port: 9000 });
+
+    expect(net.createConnection).toHaveBeenCalledWith(
+      { host: "localhost", port: 9000 },
+      expect.any(Function)
+    );
+
+    expect(mockSocket.on).toHaveBeenCalledWith("error", expect.any(Function));
+    expect(mockSocket.on).toHaveBeenCalledWith("data", expect.any(Function));
+    expect(handler).toBeInstanceOf(EventEmitter);
+  });
+
+  test("should build a FastCGI packet", () => {
+    const content = Buffer.from("test");
+
+    const packet = buildFastCGIPacket(1, 1, content);
+    expect(packet.length).toBe(16); // Header + padded content
+    expect(packet.readUInt8(0)).toBe(1); // version
+    expect(packet.readUInt8(1)).toBe(1); // type
+    expect(packet.readUInt16BE(2)).toBe(1); // requestID
+    expect(packet.readUInt16BE(4)).toBe(4); // content length
+    expect(packet.readUInt8(6)).toBe(4); // padding length
+  });
+
+  test("should write FastCGI packets to the socket", () => {
+    const handler = new FastCGIHandler({});
+    const content = Buffer.from("test");
+
+    writeFastCGIPacket(handler.socket, 1, handler.requestID, content);
+    expect(mockSocket.write).toHaveBeenCalledTimes(1);
+    expect(mockSocket.write).toHaveBeenCalledWith(expect.any(Buffer));
+  });
+
+  // eslint-disable-next-line jest/no-done-callback
+  test("should handle socket data and emit events", (done) => {
+    const handler = new FastCGIHandler({});
+    handler.stdout.on("data", (chunk) => {
+      expect(chunk).toStrictEqual(Buffer.from("Hello World"));
+      done();
+    });
+
+    // Simulate a FastCGI STDOUT packet
+    const packet = buildFastCGIPacket(
+      constants.STDOUT,
+      handler.requestID,
+      Buffer.from("Hello World")
+    );
+
+    mockSocket.dataHandler(packet);
+  });
+
+  // eslint-disable-next-line jest/no-done-callback
+  test("should handle END_REQUEST and emit 'exit' event", (done) => {
+    const handler = new FastCGIHandler({});
+
+    handler.on("exit", (code, signal) => {
+      expect(code).toBe(0);
+      expect(signal).toBeNull();
+      done();
+    });
+
+    // Simulate an END_REQUEST packet
+    const content = Buffer.alloc(8);
+    content.writeUInt32BE(0, 0); // appStatus
+    content.writeUInt8(0, 4); // protocolStatus
+    const packet = buildFastCGIPacket(
+      constants.END_REQUEST,
+      handler.requestID,
+      content
+    );
+
+    mockSocket.dataHandler(packet);
+  });
+
+  test("should handle UNKNOWN_TYPE and discard it", () => {
+    const handler = new FastCGIHandler({});
+    const dataListener = jest.fn();
+    handler.stdout.on("data", dataListener);
+
+    // Simulate an UNKNOWN_TYPE packet
+    const packet = buildFastCGIPacket(
+      constants.UNKNOWN_TYPE,
+      handler.requestID,
+      Buffer.alloc(0)
+    );
+
+    mockSocket.dataHandler(packet);
+    expect(dataListener).not.toHaveBeenCalledWith();
+  });
+
+  test("should build name-value pairs correctly", () => {
+    const pair = buildNameValuePair("key", "value");
+    expect(pair.length).toBe(10); // 1 byte for key length, 1 for value length, and key-value content
+    expect(pair.toString("utf8", 2)).toBe("keyvalue");
+  });
+
+  test("should send environment variables on init", () => {
+    const env = { FOO: "BAR", BAZ: "QUX" };
+    const handler = new FastCGIHandler({ env });
+
+    handler.init();
+
+    expect(mockSocket.write).toHaveBeenCalled();
+    const calls = mockSocket.write.mock.calls;
+
+    const envPacket = calls.find(([arg]) => arg.includes(Buffer.from("FOO")));
+    expect(envPacket).toBeTruthy();
+  });
+});