Implement PROXY protocol v1 support in SmartProxy

- Added ProxyProtocolParser class for parsing and generating PROXY protocol v1 headers.
- Integrated PROXY protocol parsing into RouteConnectionHandler for handling incoming connections from trusted proxies.
- Implemented WrappedSocket class to encapsulate real client information.
- Configured SmartProxy to accept and send PROXY protocol headers in routing actions.
- Developed comprehensive unit tests for PROXY protocol parsing and generation.
- Documented usage patterns, configuration, and best practices for proxy chaining scenarios.
- Added security and performance considerations for PROXY protocol implementation.

test/test.proxy-protocol.ts

@@ -0,0 +1,133 @@
+import { expect, tap } from '@git.zone/tstest/tapbundle';
+import * as smartproxy from '../ts/index.js';
+import { ProxyProtocolParser } from '../ts/core/utils/proxy-protocol.js';
+
+tap.test('PROXY protocol v1 parser - valid headers', async () => {
+  // Test TCP4 format
+  const tcp4Header = Buffer.from('PROXY TCP4 192.168.1.1 10.0.0.1 56324 443\r\n', 'ascii');
+  const tcp4Result = ProxyProtocolParser.parse(tcp4Header);
+  
+  expect(tcp4Result.proxyInfo).property('protocol').toEqual('TCP4');
+  expect(tcp4Result.proxyInfo).property('sourceIP').toEqual('192.168.1.1');
+  expect(tcp4Result.proxyInfo).property('sourcePort').toEqual(56324);
+  expect(tcp4Result.proxyInfo).property('destinationIP').toEqual('10.0.0.1');
+  expect(tcp4Result.proxyInfo).property('destinationPort').toEqual(443);
+  expect(tcp4Result.remainingData.length).toEqual(0);
+  
+  // Test TCP6 format
+  const tcp6Header = Buffer.from('PROXY TCP6 2001:db8::1 2001:db8::2 56324 443\r\n', 'ascii');
+  const tcp6Result = ProxyProtocolParser.parse(tcp6Header);
+  
+  expect(tcp6Result.proxyInfo).property('protocol').toEqual('TCP6');
+  expect(tcp6Result.proxyInfo).property('sourceIP').toEqual('2001:db8::1');
+  expect(tcp6Result.proxyInfo).property('sourcePort').toEqual(56324);
+  expect(tcp6Result.proxyInfo).property('destinationIP').toEqual('2001:db8::2');
+  expect(tcp6Result.proxyInfo).property('destinationPort').toEqual(443);
+  
+  // Test UNKNOWN protocol
+  const unknownHeader = Buffer.from('PROXY UNKNOWN\r\n', 'ascii');
+  const unknownResult = ProxyProtocolParser.parse(unknownHeader);
+  
+  expect(unknownResult.proxyInfo).property('protocol').toEqual('UNKNOWN');
+  expect(unknownResult.proxyInfo).property('sourceIP').toEqual('');
+  expect(unknownResult.proxyInfo).property('sourcePort').toEqual(0);
+});
+
+tap.test('PROXY protocol v1 parser - with remaining data', async () => {
+  const headerWithData = Buffer.concat([
+    Buffer.from('PROXY TCP4 192.168.1.1 10.0.0.1 56324 443\r\n', 'ascii'),
+    Buffer.from('GET / HTTP/1.1\r\n', 'ascii')
+  ]);
+  
+  const result = ProxyProtocolParser.parse(headerWithData);
+  
+  expect(result.proxyInfo).property('protocol').toEqual('TCP4');
+  expect(result.proxyInfo).property('sourceIP').toEqual('192.168.1.1');
+  expect(result.remainingData.toString()).toEqual('GET / HTTP/1.1\r\n');
+});
+
+tap.test('PROXY protocol v1 parser - invalid headers', async () => {
+  // Not a PROXY protocol header
+  const notProxy = Buffer.from('GET / HTTP/1.1\r\n', 'ascii');
+  const notProxyResult = ProxyProtocolParser.parse(notProxy);
+  expect(notProxyResult.proxyInfo).toBeNull();
+  expect(notProxyResult.remainingData).toEqual(notProxy);
+  
+  // Invalid protocol
+  expect(() => {
+    ProxyProtocolParser.parse(Buffer.from('PROXY INVALID 1.1.1.1 2.2.2.2 80 443\r\n', 'ascii'));
+  }).toThrow();
+  
+  // Wrong number of fields
+  expect(() => {
+    ProxyProtocolParser.parse(Buffer.from('PROXY TCP4 192.168.1.1 10.0.0.1 56324\r\n', 'ascii'));
+  }).toThrow();
+  
+  // Invalid port
+  expect(() => {
+    ProxyProtocolParser.parse(Buffer.from('PROXY TCP4 192.168.1.1 10.0.0.1 99999 443\r\n', 'ascii'));
+  }).toThrow();
+  
+  // Invalid IP for protocol
+  expect(() => {
+    ProxyProtocolParser.parse(Buffer.from('PROXY TCP4 2001:db8::1 10.0.0.1 56324 443\r\n', 'ascii'));
+  }).toThrow();
+});
+
+tap.test('PROXY protocol v1 parser - incomplete headers', async () => {
+  // Header without terminator
+  const incomplete = Buffer.from('PROXY TCP4 192.168.1.1 10.0.0.1 56324 443', 'ascii');
+  const result = ProxyProtocolParser.parse(incomplete);
+  
+  expect(result.proxyInfo).toBeNull();
+  expect(result.remainingData).toEqual(incomplete);
+  
+  // Header exceeding max length - create a buffer that actually starts with PROXY
+  const longHeader = Buffer.from('PROXY TCP4 ' + '1'.repeat(100), 'ascii');
+  expect(() => {
+    ProxyProtocolParser.parse(longHeader);
+  }).toThrow();
+});
+
+tap.test('PROXY protocol v1 generator', async () => {
+  // Generate TCP4 header
+  const tcp4Info = {
+    protocol: 'TCP4' as const,
+    sourceIP: '192.168.1.1',
+    sourcePort: 56324,
+    destinationIP: '10.0.0.1',
+    destinationPort: 443
+  };
+  
+  const tcp4Header = ProxyProtocolParser.generate(tcp4Info);
+  expect(tcp4Header.toString('ascii')).toEqual('PROXY TCP4 192.168.1.1 10.0.0.1 56324 443\r\n');
+  
+  // Generate TCP6 header
+  const tcp6Info = {
+    protocol: 'TCP6' as const,
+    sourceIP: '2001:db8::1',
+    sourcePort: 56324,
+    destinationIP: '2001:db8::2',
+    destinationPort: 443
+  };
+  
+  const tcp6Header = ProxyProtocolParser.generate(tcp6Info);
+  expect(tcp6Header.toString('ascii')).toEqual('PROXY TCP6 2001:db8::1 2001:db8::2 56324 443\r\n');
+  
+  // Generate UNKNOWN header
+  const unknownInfo = {
+    protocol: 'UNKNOWN' as const,
+    sourceIP: '',
+    sourcePort: 0,
+    destinationIP: '',
+    destinationPort: 0
+  };
+  
+  const unknownHeader = ProxyProtocolParser.generate(unknownInfo);
+  expect(unknownHeader.toString('ascii')).toEqual('PROXY UNKNOWN\r\n');
+});
+
+// Skipping integration tests for now - focus on unit tests
+// Integration tests would require more complex setup and teardown
+
+tap.start();