refactor: socket.js

app/server/socket.js

@@ -15,25 +15,15 @@ const dnsPromises = require('dns').promises;
 let termCols;
 let termRows;
 
-// public
-module.exports = function appSocket(socket) {
-  async function setupConnection() {
-    // if websocket connection arrives without an express session, kill it
-    if (!socket.request.session) {
-      socket.emit('401 UNAUTHORIZED');
-      debugWebSSH2('SOCKET: No Express Session / REJECTED');
-      socket.disconnect(true);
-      return;
-    }
-
-    /**
+/**
  * Error handling for various events. Outputs error to client, logs to
  * server, destroys session and disconnects socket.
+ * @param {object} socket Socket information
  * @param {string} myFunc Function calling this function
  * @param {object} err    error object or error message
  */
-    // eslint-disable-next-line complexity
-    function SSHerror(myFunc, err) {
+// eslint-disable-next-line complexity
+function SSHerror(socket, myFunc, err) {
   let theError;
   if (socket.request.session) {
     // we just want the first error of the session to pass to the client
@@ -66,12 +56,9 @@ module.exports = function appSocket(socket) {
     socket.disconnect(true);
   }
   debugWebSSH2(`SSHerror ${myFunc}${theError}`);
-    }
-    // If configured, check that requsted host is in a permitted subnet
-    if (
-      (((socket.request.session || {}).ssh || {}).allowedSubnets || {}).length &&
-      socket.request.session.ssh.allowedSubnets.length > 0
-    ) {
+}
+
+async function checkSubnet(socket) {
   let ipaddress = socket.request.session.ssh.host;
   if (!validator.isIP(`${ipaddress}`)) {
     try {
@@ -98,8 +85,23 @@ module.exports = function appSocket(socket) {
     );
     socket.emit('ssherror', '401 UNAUTHORIZED');
     socket.disconnect(true);
+  }
+}
+
+// public
+module.exports = function appSocket(socket) {
+  async function setupConnection() {
+    // if websocket connection arrives without an express session, kill it
+    if (!socket.request.session) {
+      socket.emit('401 UNAUTHORIZED');
+      debugWebSSH2('SOCKET: No Express Session / REJECTED');
+      socket.disconnect(true);
       return;
     }
+
+    // If configured, check that requsted host is in a permitted subnet
+    if (socket.request.session?.ssh?.allowedSubnets?.length > 0) {
+      checkSubnet(socket);
     }
 
     const conn = new SSH();
@@ -139,7 +141,7 @@ module.exports = function appSocket(socket) {
         },
         (err, stream) => {
           if (err) {
-            SSHerror(`EXEC ERROR${err}`);
+            SSHerror(socket, `EXEC ERROR`, err);
             conn.end();
             return;
           }
@@ -161,12 +163,12 @@ module.exports = function appSocket(socket) {
           socket.on('disconnect', (reason) => {
             debugWebSSH2(`SOCKET DISCONNECT: ${reason}`);
             const errMsg = { message: reason };
-            SSHerror('CLIENT SOCKET DISCONNECT', errMsg);
+            SSHerror(socket, 'CLIENT SOCKET DISCONNECT', errMsg);
             conn.end();
             // socket.request.session.destroy()
           });
           socket.on('error', (errMsg) => {
-            SSHerror('SOCKET ERROR', errMsg);
+            SSHerror(socket, 'SOCKET ERROR', errMsg);
             conn.end();
           });
 
@@ -174,15 +176,7 @@ module.exports = function appSocket(socket) {
             socket.emit('data', data.toString('utf-8'));
           });
           stream.on('close', (code, signal) => {
-            const errMsg = {
-              message:
-                code || signal
-                  ? (code ? `CODE: ${code}` : '') +
-                    (code && signal ? ', ' : '') +
-                    (signal ? `SIGNAL: ${signal}` : '')
-                  : undefined,
-            };
-            SSHerror('STREAM CLOSE', errMsg);
+            SSHerror(socket, 'STREAM CLOSE', { message: code, signal });
             conn.end();
           });
           stream.stderr.on('data', (data) => {
@@ -193,15 +187,15 @@ module.exports = function appSocket(socket) {
     });
 
     conn.on('end', (err) => {
-      SSHerror('CONN END BY HOST', err);
+      SSHerror(socket, 'CONN END BY HOST', err);
     });
     conn.on('close', (err) => {
-      SSHerror('CONN CLOSE', err);
+      SSHerror(socket, 'CONN CLOSE', err);
     });
     conn.on('error', (err) => {
-      SSHerror('CONN ERROR', err);
+      SSHerror(socket, 'CONN ERROR', err);
     });
-    conn.on('keyboard-interactive', (name, instructions, instructionsLang, prompts, finish) => {
+    conn.on('keyboard-interactive', (_name, _instructions, _instructionsLang, _prompts, finish) => {
       debugWebSSH2("conn.on('keyboard-interactive')");
       finish([socket.request.session.userpassword]);
     });