http: ignore trailing dot when matching NO_PROXY

lib/internal/http.js

@@ -75,6 +75,11 @@ function ipToInt(ip) {
   return result >>> 0;
 }
 
+// Follow curl's behavior: ignore a trailing dot in both the host and the NO_PROXY entries.
+function stripTrailingDot(host) {
+  return host.length > 1 && host[host.length - 1] === '.' ? host.slice(0, -1) : host;
+}
+
 // There are two factors in play when proxying the request:
 // 1. What the request protocol is, that is, whether users are sending it via
 //    http.request or https.request, or whether they are sending
@@ -137,7 +142,7 @@ class ProxyConfig {
       this.auth = `Basic ${Buffer.from(auth).toString('base64')}`;
     }
     if (noProxyList) {
-      this.bypassList = noProxyList.split(',').map((entry) => entry.trim().toLowerCase());
+      this.bypassList = noProxyList.split(',').map((entry) => stripTrailingDot(entry.trim().toLowerCase()));
     } else {
       this.bypassList = []; // No bypass list provided.
     }
@@ -159,7 +164,7 @@ class ProxyConfig {
       return true; // No bypass list, always use the proxy.
     }
 
-    const host = hostname.toLowerCase();
+    const host = stripTrailingDot(hostname.toLowerCase());
     const hostWithPort = port ? `${host}:${port}` : host;
 
     for (let i = 0; i < bypassList.length; i++) {

test/client-proxy/test-http-proxy-request-no-proxy-domain.mjs

@@ -10,7 +10,7 @@ import { runProxiedRequest } from '../common/proxy-server.js';
 const server = http.createServer(common.mustCall((req, res) => {
   res.writeHead(200, { 'Content-Type': 'text/plain' });
   res.end('Hello World\n');
-}, 5));
+}, 7));
 server.on('error', common.mustNotCall((err) => { console.error('Server error', err); }));
 server.listen(0, '127.0.0.1');
 await once(server, 'listening');
@@ -78,6 +78,44 @@ await once(proxy, 'listening');
   assert.strictEqual(signal, null);
 }
 
+// Test NO_PROXY ignores a trailing dot in the request hostname.
+{
+  const { code, signal, stderr, stdout } = await runProxiedRequest({
+    NODE_USE_ENV_PROXY: 1,
+    REQUEST_URL: `http://test.example.com.:${server.address().port}/test`,
+    HTTP_PROXY: `http://localhost:${proxy.address().port}`,
+    RESOLVE_TO_LOCALHOST: 'test.example.com.',
+    NO_PROXY: 'test.example.com',
+  });
+
+  // The request should succeed and bypass proxy.
+  assert.match(stdout, /Status Code: 200/);
+  assert.match(stdout, /Hello World/);
+  assert.match(stdout, /Resolving lookup for test\.example\.com\./);
+  assert.strictEqual(stderr.trim(), '');
+  assert.strictEqual(code, 0);
+  assert.strictEqual(signal, null);
+}
+
+// Test NO_PROXY ignores a trailing dot in the entry.
+{
+  const { code, signal, stderr, stdout } = await runProxiedRequest({
+    NODE_USE_ENV_PROXY: 1,
+    REQUEST_URL: `http://test.example.com:${server.address().port}/test`,
+    HTTP_PROXY: `http://localhost:${proxy.address().port}`,
+    RESOLVE_TO_LOCALHOST: 'test.example.com',
+    NO_PROXY: 'test.example.com.',
+  });
+
+  // The request should succeed and bypass proxy.
+  assert.match(stdout, /Status Code: 200/);
+  assert.match(stdout, /Hello World/);
+  assert.match(stdout, /Resolving lookup for test\.example\.com/);
+  assert.strictEqual(stderr.trim(), '');
+  assert.strictEqual(code, 0);
+  assert.strictEqual(signal, null);
+}
+
 // Test NO_PROXY with leading-dot entry should NOT match partial domain names.
 // Regression test: .example.com must not match notexample.com or badexample.com.
 {