Client: emit error on pre-handshake connection loss

Fixes: mscdex#610
alex3d · Nov 8, 2020 · 93666dc · 93666dc
1 parent 11f7d90
commit 93666dc
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Showing 2 changed files with 55 additions and 3 deletions.
diff --git a/lib/client.js b/lib/client.js
@@ -34,7 +34,7 @@ const {
 const Protocol = require('./protocol/Protocol.js');
 const { parseKey } = require('./protocol/keyParser.js');
 const { SFTP } = require('./protocol/SFTP.js');
-const { readUInt32BE } = require('./protocol/utils.js');
+const { makeError, readUInt32BE } = require('./protocol/utils.js');
 
 const agentQuery = require('./agent.js');
 const {
@@ -270,6 +270,7 @@ class Client extends EventEmitter {
 
     const sock = this._sock = (cfg.sock || new Socket());
     let ready = false;
+    let sawHeader = false;
     if (this._protocol)
       this._protocol.cleanup();
     const DEBUG_HANDLER = (!debug ? undefined : (p, display, msg) => {
@@ -292,6 +293,7 @@ class Client extends EventEmitter {
         } catch {}
       },
       onHeader: (header) => {
+        sawHeader = true;
         this._remoteVer = header.versions.software;
         if (header.greeting)
           this.emit('greeting', header.greeting);
@@ -680,6 +682,27 @@ class Client extends EventEmitter {
     }
     this._resetKA = resetKA;
 
+    {
+      let errorEmitted = false;
+      this.once('error', (err) => {
+        errorEmitted = true;
+        if (this.listenerCount('error') === 0)
+          this.emit('error', err);
+      });
+      let called = false;
+      // Intentional `var`
+      // eslint-disable-next-line no-var
+      var onDone = () => {
+        if (called)
+          return;
+        called = true;
+        if (!errorEmitted && !sawHeader) {
+          const err =
+            makeError('Connection lost before handshake', 'protocol', true);
+          this.emit('error', err);
+        }
+      };
+    }
     sock.on('connect', () => {
       debug && debug('Socket connected');
       this.emit('connect');
@@ -692,12 +715,16 @@ class Client extends EventEmitter {
       this.emit('error', err);
     }).on('end', () => {
       debug && debug('Socket ended');
+      // eslint-disable-next-line block-scoped-var
+      onDone();
       proto.cleanup();
       clearTimeout(this._readyTimeout);
       clearInterval(katimer);
       this.emit('end');
     }).on('close', () => {
       debug && debug('Socket closed');
+      // eslint-disable-next-line block-scoped-var
+      onDone();
       proto.cleanup();
       clearTimeout(this._readyTimeout);
       clearInterval(katimer);

diff --git a/test/test-misc-client-server.js b/test/test-misc-client-server.js
@@ -668,8 +668,7 @@ const setup = setupSimple.bind(undefined, debug);
   let cliError;
   client.on('ready', mustNotCall()).on('error', mustCall((err) => {
     if (cliError) {
-      assert(/all configured/i.test(err.message),
-             'Wrong error message');
+      assert(/all configured/i.test(err.message), 'Wrong error message');
     } else {
       cliError = err;
       assert(/signing/i.test(err.message), 'Wrong error message');
@@ -1246,3 +1245,29 @@ const setup = setupSimple.bind(undefined, debug);
     });
   }));
 }
+
+{
+  const { client } = setup_(
+    'Client error should be emitted on bad/nonexistent greeting',
+    {
+      client: clientCfg,
+      noClientError: true,
+      noForceClientReady: true,
+    },
+  );
+
+  const badServer = net.createServer(mustCall((s) => {
+    badServer.close();
+    s.end();
+  })).listen(0, 'localhost', mustCall(() => {
+    client.on('error', mustCall((err) => {
+      client.end();
+    })).on('ready', mustNotCall()).on('close', mustCall(() => {}));
+    client.connect({
+      host: 'localhost',
+      port: badServer.address().port,
+      user: 'foo',
+      password: 'bar',
+    });
+  }));
+}