From dbba7232469094f9061572a95a8a32254c45d5b6 Mon Sep 17 00:00:00 2001
From: Olivier MICHAUD <o.michaud@hsrv.fr>
Date: Wed, 30 Sep 2020 22:21:05 +0200
Subject: [PATCH] Add a range option to server to specify specific port client
 attribution

---
 bin/server           |  5 +++++
 lib/ClientManager.js |  4 ++++
 lib/TunnelAgent.js   | 15 +++++++++++----
 3 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/bin/server b/bin/server
index a6bba9d8..10fd77d0 100755
--- a/bin/server
+++ b/bin/server
@@ -31,6 +31,10 @@ const argv = optimist
         default: 10,
         describe: 'maximum number of tcp sockets each client is allowed to establish at one time (the tunnels)'
     })
+    .options('range', {
+        default: null,
+        describe: 'will bind incoming connections only on ports in range xxx:xxxx'
+    })
     .argv;
 
 if (argv.help) {
@@ -42,6 +46,7 @@ const server = CreateServer({
     max_tcp_sockets: argv['max-sockets'],
     secure: argv.secure,
     domain: argv.domain,
+    range: argv.range,
 });
 
 server.listen(argv.port, argv.address, () => {
diff --git a/lib/ClientManager.js b/lib/ClientManager.js
index e1a78386..6d97265c 100644
--- a/lib/ClientManager.js
+++ b/lib/ClientManager.js
@@ -3,6 +3,7 @@ import Debug from 'debug';
 
 import Client from './Client';
 import TunnelAgent from './TunnelAgent';
+import PortManager from "./PortManager";
 
 // Manage sets of clients
 //
@@ -13,6 +14,7 @@ class ClientManager {
 
         // id -> client instance
         this.clients = new Map();
+        this.portManager = new PortManager({range: this.opt.range||null})
 
         // statistics
         this.stats = {
@@ -39,6 +41,7 @@ class ClientManager {
 
         const maxSockets = this.opt.max_tcp_sockets;
         const agent = new TunnelAgent({
+            portManager: this.portManager,
             clientId: id,
             maxSockets: 10,
         });
@@ -79,6 +82,7 @@ class ClientManager {
         if (!client) {
             return;
         }
+        this.portManager.release(client.agent.port);
         --this.stats.tunnels;
         delete this.clients[id];
         client.close();
diff --git a/lib/TunnelAgent.js b/lib/TunnelAgent.js
index efc2231b..a953d726 100644
--- a/lib/TunnelAgent.js
+++ b/lib/TunnelAgent.js
@@ -20,6 +20,9 @@ class TunnelAgent extends Agent {
 
         // sockets we can hand out via createConnection
         this.availableSockets = [];
+        this.port = null;
+        this.clientId = options.clientId
+        this.portManager = options.portManager || null;
 
         // when a createConnection cannot return a socket, it goes into a queue
         // once a socket is available it is handed out to the next callback
@@ -63,13 +66,14 @@ class TunnelAgent extends Agent {
         });
 
         return new Promise((resolve) => {
-            server.listen(() => {
-                const port = server.address().port;
-                this.debug('tcp server listening on port: %d', port);
+            const port = this.portManager ? this.portManager.getNextAvailable(this.options.clientId) : null;
+            server.listen(port,() => {
+                this.port = server.address().port
+                this.debug('tcp server listening on port: %d (%s)', this.port, this.clientId);
 
                 resolve({
                     // port for lt client tcp connections
-                    port: port,
+                    port: this.port,
                 });
             });
         });
@@ -115,6 +119,9 @@ class TunnelAgent extends Agent {
         socket.once('error', (err) => {
             // we do not log these errors, sessions can drop from clients for many reasons
             // these are not actionable errors for our server
+            if(this.portManager){
+                this.portManager.release(this.port);
+            }
             socket.destroy();
         });