feat: add no-proxy support (#1482)

src/ProxyResolver.ts

@@ -0,0 +1,70 @@
+// Based on https://github.com/Rob--W/proxy-from-env/tree/caf8c32301afdac8b5feaf346028bd8240690144
+// See https://github.com/Rob--W/proxy-from-env/blob/caf8c32301afdac8b5feaf346028bd8240690144/LICENSE
+import type * as http from 'node:http';
+
+const DEFAULT_PORTS: Record<string, number> = {
+  http: 80,
+  https: 443,
+};
+export interface ProxyOptions {
+  readonly noProxy?: string;
+  readonly httpsProxy?: string;
+  readonly httpProxy?: string;
+}
+
+export class ProxyResolver {
+  options: ProxyOptions;
+  constructor(options: ProxyOptions) {
+    this.options = options;
+  }
+
+  getProxyForUrl(url: string, _req: http.ClientRequest): string {
+    return this.getProxyForUrlOptions(url, this.options);
+  }
+
+  private getProxyForUrlOptions(url: string | URL, options?: ProxyOptions): string {
+    let parsedUrl: URL;
+    try {
+      parsedUrl = typeof url === 'string' ? new URL(url) : url;
+    } catch (_) {
+      return ''; // Don't proxy invalid URLs.
+    }
+    const proto = parsedUrl.protocol.split(':', 1)[0];
+    if (!proto) return ''; // Don't proxy URLs without a protocol.
+    const hostname = parsedUrl.host;
+    const port = parseInt(parsedUrl.port || '') || DEFAULT_PORTS[proto] || 0;
+
+    if (options?.noProxy && !this.shouldProxy(hostname, port, options.noProxy)) return '';
+    if (proto === 'http' && options?.httpProxy) return options.httpProxy;
+    if (proto === 'https' && options?.httpsProxy) return options.httpsProxy;
+    return ''; // No proxy configured for this protocol or unknown protocol
+  }
+
+  private shouldProxy(hostname: string, port: number, noProxy: string): boolean {
+    if (!noProxy) return true;
+    if (noProxy === '*') return false; // Never proxy if wildcard is set.
+
+    return noProxy.split(/[,\s]/).every((proxy) => {
+      if (!proxy) return true; // Skip zero-length hosts.
+
+      const parsedProxy = proxy.match(/^(.+):(\d+)$/);
+      const parsedProxyHostname = parsedProxy ? parsedProxy[1] : proxy;
+      const parsedProxyPort = parsedProxy?.[2] ? parseInt(parsedProxy[2]) : 0;
+
+      if (parsedProxyPort && parsedProxyPort !== port) return true; // Skip if ports don't match.
+
+      if (parsedProxyHostname && !/^[.*]/.test(parsedProxyHostname)) {
+        // No wildcards, so stop proxying if there is an exact match.
+        return hostname !== parsedProxyHostname;
+      }
+
+      let cleanProxyHostname = parsedProxyHostname;
+      if (parsedProxyHostname && parsedProxyHostname.charAt(0) === '*') {
+        // Remove leading wildcard.
+        cleanProxyHostname = parsedProxyHostname.slice(1);
+      }
+      // Stop proxying if the hostname ends with the no_proxy host.
+      return !cleanProxyHostname || !hostname.endsWith(cleanProxyHostname);
+    });
+  }
+}