http: use 0 as default for requests limit

doc/api/http.md

@@ -1357,12 +1357,12 @@ explicitly.
 added: v16.10.0
 -->
 
-* {number} Requests per socket. **Default:** null (no limit)
+* {number} Requests per socket. **Default:** 0 (no limit)
 
 The maximum number of requests socket can handle
 before closing keep alive connection.
 
-A value of `null` will disable the limit.
+A value of `0` will disable the limit.
 
 When the limit is reached it will set the `Connection` header value to `close`,
 but will not actually close the connection, subsequent requests sent

lib/_http_server.js

@@ -394,7 +394,7 @@ function Server(options, requestListener) {
   this.timeout = 0;
   this.keepAliveTimeout = 5000;
   this.maxHeadersCount = null;
-  this.maxRequestsPerSocket = null;
+  this.maxRequestsPerSocket = 0;
   this.headersTimeout = 60 * 1000; // 60 seconds
   this.requestTimeout = 0;
 }
@@ -908,13 +908,18 @@ function parserOnIncoming(server, socket, state, req, keepAlive) {
   let handled = false;
 
   if (req.httpVersionMajor === 1 && req.httpVersionMinor === 1) {
-    if (typeof server.maxRequestsPerSocket === 'number') {
+    const isRequestsLimitSet = (
+      typeof server.maxRequestsPerSocket === 'number' &&
+      server.maxRequestsPerSocket > 0
+    );
+
+    if (isRequestsLimitSet) {
       state.requestsCount++;
       res.maxRequestsOnConnectionReached = (
         server.maxRequestsPerSocket <= state.requestsCount);
     }
 
-    if (typeof server.maxRequestsPerSocket === 'number' &&
+    if (isRequestsLimitSet &&
       (server.maxRequestsPerSocket < state.requestsCount)) {
       handled = true;
 

test/parallel/test-http-server-keep-alive-defaults.js

@@ -0,0 +1,76 @@
+'use strict';
+
+const common = require('../common');
+const net = require('net');
+const http = require('http');
+const assert = require('assert');
+
+const bodySent = 'This is my request';
+
+function assertResponse(headers, body, expectClosed) {
+  assert.match(headers, /Connection: keep-alive\r\n/m);
+  assert.match(headers, /Keep-Alive: timeout=5\r\n/m);
+  assert.match(body, /Hello World!/m);
+}
+
+function writeRequest(socket) {
+  socket.write('POST / HTTP/1.1\r\n');
+  socket.write('Connection: keep-alive\r\n');
+  socket.write('Content-Type: text/plain\r\n');
+  socket.write(`Content-Length: ${bodySent.length}\r\n\r\n`);
+  socket.write(`${bodySent}\r\n`);
+  socket.write('\r\n\r\n');
+}
+
+const server = http.createServer((req, res) => {
+  let body = '';
+  req.on('data', (data) => {
+    body += data;
+  });
+
+  req.on('end', () => {
+    if (req.method === 'POST') {
+      assert.strictEqual(bodySent, body);
+    }
+
+    res.writeHead(200, { 'Content-Type': 'text/plain' });
+    res.write('Hello World!');
+    res.end();
+  });
+});
+
+server.listen(0, common.mustCall((res) => {
+  assert.strictEqual(server.maxRequestsPerSocket, 0);
+
+  const socket = new net.Socket();
+
+  socket.on('end', common.mustCall(() => {
+    server.close();
+  }));
+
+  socket.on('ready', common.mustCall(() => {
+    writeRequest(socket);
+    writeRequest(socket);
+    writeRequest(socket);
+    writeRequest(socket);
+  }));
+
+  let buffer = '';
+
+  socket.on('data', (data) => {
+    buffer += data;
+
+    const responseParts = buffer.trim().split('\r\n\r\n');
+
+    if (responseParts.length === 8) {
+      assertResponse(responseParts[0], responseParts[1]);
+      assertResponse(responseParts[2], responseParts[3]);
+      assertResponse(responseParts[4], responseParts[5]);
+      assertResponse(responseParts[6], responseParts[7]);
+
+      socket.end();
+    }
+  });
+
+  socket.connect({ port: server.address().port });
+}));

test/parallel/test-http-server-keep-alive-max-requests-null.js

@@ -0,0 +1,75 @@
+'use strict';
+
+const common = require('../common');
+const net = require('net');
+const http = require('http');
+const assert = require('assert');
+
+const bodySent = 'This is my request';
+
+function assertResponse(headers, body, expectClosed) {
+  assert.match(headers, /Connection: keep-alive\r\n/m);
+  assert.match(headers, /Keep-Alive: timeout=5\r\n/m);
+  assert.match(body, /Hello World!/m);
+}
+
+function writeRequest(socket) {
+  socket.write('POST / HTTP/1.1\r\n');
+  socket.write('Connection: keep-alive\r\n');
+  socket.write('Content-Type: text/plain\r\n');
+  socket.write(`Content-Length: ${bodySent.length}\r\n\r\n`);
+  socket.write(`${bodySent}\r\n`);
+  socket.write('\r\n\r\n');
+}
+
+const server = http.createServer((req, res) => {
+  let body = '';
+  req.on('data', (data) => {
+    body += data;
+  });
+
+  req.on('end', () => {
+    if (req.method === 'POST') {
+      assert.strictEqual(bodySent, body);
+    }
+
+    res.writeHead(200, { 'Content-Type': 'text/plain' });
+    res.write('Hello World!');
+    res.end();
+  });
+});
+
+server.maxRequestsPerSocket = null;
+server.listen(0, common.mustCall((res) => {
+  const socket = new net.Socket();
+
+  socket.on('end', common.mustCall(() => {
+    server.close();
+  }));
+
+  socket.on('ready', common.mustCall(() => {
+    writeRequest(socket);
+    writeRequest(socket);
+    writeRequest(socket);
+    writeRequest(socket);
+  }));
+
+  let buffer = '';
+
+  socket.on('data', (data) => {
+    buffer += data;
+
+    const responseParts = buffer.trim().split('\r\n\r\n');
+
+    if (responseParts.length === 8) {
+      assertResponse(responseParts[0], responseParts[1]);
+      assertResponse(responseParts[2], responseParts[3]);
+      assertResponse(responseParts[4], responseParts[5]);
+      assertResponse(responseParts[6], responseParts[7]);
+
+      socket.end();
+    }
+  });
+
+  socket.connect({ port: server.address().port });
+}));