Implement a proxy blocking tarball requests for packages containing malware.

packages/safe-chain/src/registryProxy/registryProxy.js

@@ -0,0 +1,119 @@
+import * as http from "http";
+import { tunnelRequest } from "./tunnelRequestHandler.js";
+import { mitmConnect } from "./mitmRequestHandler.js";
+import { getCaCertPath } from "./certUtils.js";
+import { auditChanges } from "../scanning/audit/index.js";
+import { knownRegistries, parsePackageFromUrl } from "./parsePackageFromUrl.js";
+
+const state = {
+  port: null,
+  blockedRequests: [],
+};
+
+export function createSafeChainProxy() {
+  const server = createProxyServer();
+  server.on("connect", handleConnect);
+
+  return {
+    startServer: () => startServer(server),
+    stopServer: () => stopServer(server),
+    getBlockedRequests: () => state.blockedRequests,
+  };
+}
+
+function getSafeChainProxyEnvironmentVariables() {
+  return {
+    HTTPS_PROXY: `http://localhost:${state.port}`,
+    GLOBAL_AGENT_HTTP_PROXY: `http://localhost:${state.port}`,
+    NODE_EXTRA_CA_CERTS: getCaCertPath(),
+  };
+}
+
+export function mergeSafeChainProxyEnvironmentVariables(env) {
+  const proxyEnv = getSafeChainProxyEnvironmentVariables();
+
+  for (const key of Object.keys(env)) {
+    // If we were to simply copy all env variables, we might overwrite
+    // the proxy settings set by safe-chain when casing varies (e.g. http_proxy vs HTTP_PROXY)
+    // So we only copy the variable if it's not already set in a different case
+    const upperKey = key.toUpperCase();
+
+    if (!proxyEnv[upperKey]) {
+      proxyEnv[upperKey] = env[key];
+    }
+  }
+
+  return proxyEnv;
+}
+
+function createProxyServer() {
+  const server = http.createServer((_, res) => {
+    res.writeHead(400, "Bad Request");
+    res.write(
+      "Safe-chain proxy: Direct http not supported. Only CONNECT requests are allowed."
+    );
+    res.end();
+  });
+
+  return server;
+}
+
+function startServer(server) {
+  return new Promise((resolve, reject) => {
+    server.listen(0, () => {
+      const address = server.address();
+      if (address && typeof address === "object") {
+        state.port = address.port;
+        resolve();
+      } else {
+        reject(new Error("Failed to start proxy server"));
+      }
+    });
+
+    server.on("error", (err) => {
+      reject(err);
+    });
+  });
+}
+
+function stopServer(server) {
+  return new Promise((resolve) => {
+    server.close(() => {
+      resolve();
+    });
+  });
+}
+
+function handleConnect(req, clientSocket, head) {
+  // CONNECT method is used for HTTPS requests
+  // It establishes a tunnel to the server identified by the request URL
+
+  if (knownRegistries.some((reg) => req.url.includes(reg))) {
+    // For npm and yarn registries, we want to intercept and inspect the traffic
+    // so we can block packages with malware
+    mitmConnect(req, clientSocket, isAllowedUrl);
+  } else {
+    // For other hosts, just tunnel the request to the destination tcp socket
+    tunnelRequest(req, clientSocket, head);
+  }
+}
+
+async function isAllowedUrl(url) {
+  const { packageName, version } = parsePackageFromUrl(url);
+
+  // This happens when the URL is not a tarball download url.
+  if (!packageName || !version) {
+    return true;
+  }
+
+  const auditResult = await auditChanges([
+    { name: packageName, version, type: "add" },
+  ]);
+
+  if (!auditResult.isAllowed) {
+    state.blockedRequests.push({ packageName, version, url });
+    return false;
+  }
+
+  return true;
+}