Move npm and pip mitm interception to separate files

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

@@ -0,0 +1,119 @@
+import { isMalwarePackage } from "../../scanning/audit/index.js";
+import { createInterceptorBuilder } from "./interceptorBuilder.js";
+
+const knownPipRegistries = [
+  "files.pythonhosted.org",
+  "pypi.org",
+  "pypi.python.org",
+  "pythonhosted.org",
+];
+
+/**
+ * @param {string} url
+ * @returns {import("./interceptorBuilder.js").Interceptor | undefined}
+ */
+export function pipInterceptorForUrl(url) {
+  const registry = knownPipRegistries.find((reg) => url.includes(reg));
+
+  if (registry) {
+    return buildPipInterceptor(registry);
+  }
+
+  return undefined;
+}
+
+/**
+ * @param {string} registry
+ * @returns {import("./interceptorBuilder.js").Interceptor | undefined}
+ */
+function buildPipInterceptor(registry) {
+  const builder = createInterceptorBuilder();
+
+  builder.onRequest(async (req) => {
+    const { packageName, version } = parsePipPackageFromUrl(
+      req.targetUrl,
+      registry
+    );
+    if (await isMalwarePackage(packageName, version)) {
+      req.blockRequest(403, "Forbidden - blocked by safe-chain");
+    }
+  });
+
+  return builder.build();
+}
+
+/**
+ * @param {string} url
+ * @param {string} registry
+ * @returns {{packageName: string | undefined, version: string | undefined}}
+ */
+function parsePipPackageFromUrl(url, registry) {
+  let packageName, version;
+
+  // Basic validation
+  if (!registry || typeof url !== "string") {
+    return { packageName, version };
+  }
+
+  // Quick sanity check on the URL + parse
+  let urlObj;
+  try {
+    urlObj = new URL(url);
+  } catch {
+    return { packageName, version };
+  }
+
+  // Get the last path segment (filename) and decode it (strip query & fragment automatically)
+  const lastSegment = urlObj.pathname.split("/").filter(Boolean).pop();
+  if (!lastSegment) {
+    return { packageName, version };
+  }
+
+  const filename = decodeURIComponent(lastSegment);
+
+  // Parse Python package downloads from PyPI/pythonhosted.org
+  // Example wheel: https://files.pythonhosted.org/packages/xx/yy/requests-2.28.1-py3-none-any.whl
+  // Example sdist: https://files.pythonhosted.org/packages/xx/yy/requests-2.28.1.tar.gz
+
+  // Wheel (.whl)
+  if (filename.endsWith(".whl")) {
+    const base = filename.slice(0, -4); // remove ".whl"
+    const firstDash = base.indexOf("-");
+    if (firstDash > 0) {
+      const dist = base.slice(0, firstDash); // may contain underscores
+      const rest = base.slice(firstDash + 1); // version + the rest of tags
+      const secondDash = rest.indexOf("-");
+      const rawVersion = secondDash >= 0 ? rest.slice(0, secondDash) : rest;
+      packageName = dist; // preserve underscores
+      version = rawVersion;
+      // Reject "latest" as it's a placeholder, not a real version
+      // When version is "latest", this signals the URL doesn't contain actual version info
+      // Returning undefined allows the request (see registryProxy.js isAllowedUrl)
+      if (version === "latest" || !packageName || !version) {
+        return { packageName: undefined, version: undefined };
+      }
+      return { packageName, version };
+    }
+  }
+
+  // Source dist (sdist)
+  const sdistExtMatch = filename.match(/\.(tar\.gz|zip|tar\.bz2|tar\.xz)$/i);
+  if (sdistExtMatch) {
+    const base = filename.slice(0, -sdistExtMatch[0].length);
+    const lastDash = base.lastIndexOf("-");
+    if (lastDash > 0 && lastDash < base.length - 1) {
+      packageName = base.slice(0, lastDash);
+      version = base.slice(lastDash + 1);
+      // Reject "latest" as it's a placeholder, not a real version
+      // When version is "latest", this signals the URL doesn't contain actual version info
+      // Returning undefined allows the request (see registryProxy.js isAllowedUrl)
+      if (version === "latest" || !packageName || !version) {
+        return { packageName: undefined, version: undefined };
+      }
+      return { packageName, version };
+    }
+  }
+
+  // Unknown file type or invalid
+  return { packageName: undefined, version: undefined };
+}