fix: an answer whose client went away ends quietly, and a shell whose client left before it opened is stopped.

debian-package/debian/changelog

@@ -1,3 +1,15 @@
+vpn-router (0.37.3-1) unstable; urgency=medium
+
+  fix: an answer whose client went away ends quietly, and a shell whose client left before it opened is stopped.
+
+  * The web service, the metrics service and the bootstrap server stop
+    writing an answer when its client closes the connection, and a site
+    file whose download is left no longer gets a second answer.
+  * A shell whose client closed the connection before it opened is
+    stopped and its end is logged, instead of running on.
+
+ -- Slawomir Koszewski <slawek@koszewscy.waw.pl>  Fri, 30 Oct 2026 02:03:26 +0100
+
 vpn-router (0.37.2-1) unstable; urgency=medium
 
   fix: the web service, the metrics service and the bootstrap server log a failure in one line instead of a traceback, and nothing when a client goes away.

debian-package/src/usr/lib/vpn-router/bootstrap

@@ -43,13 +43,17 @@ def report():
 class Handler(BaseHTTPRequestHandler):
     def do_GET(self):
         body = report().encode()
-        self.send_response(200)
-        self.send_header('Content-Type', 'text/plain; charset=utf-8')
-        self.send_header('Content-Length', str(len(body)))
-        self.send_header('Cache-Control', 'no-store')
-        self.send_header('Refresh', '10')
-        self.end_headers()
-        self.wfile.write(body)
+        try:
+            self.send_response(200)
+            self.send_header('Content-Type', 'text/plain; charset=utf-8')
+            self.send_header('Content-Length', str(len(body)))
+            self.send_header('Cache-Control', 'no-store')
+            self.send_header('Refresh', '10')
+            self.end_headers()
+            self.wfile.write(body)
+        except ConnectionError:
+            # The client went away before the answer was written.
+            self.close_connection = True
 
 
 def failed(request, client_address):

debian-package/src/usr/lib/vpn-router/metrics

@@ -405,15 +405,19 @@ class Handler(BaseHTTPRequestHandler):
                     registry = CollectorRegistry()
                     registry.register(Sample(current))
                     body, kind, code = generate_latest(registry), CONTENT_TYPE_LATEST, 200
-        self.send_response(code)
-        self.send_header('Content-Type', kind)
-        self.send_header('Content-Length', str(len(body)))
-        self.send_header('Cache-Control', 'no-store')
-        for name, value in extra:
-            self.send_header(name, value)
-        self.end_headers()
-        if send_body:
-            self.wfile.write(body)
+        try:
+            self.send_response(code)
+            self.send_header('Content-Type', kind)
+            self.send_header('Content-Length', str(len(body)))
+            self.send_header('Cache-Control', 'no-store')
+            for name, value in extra:
+                self.send_header(name, value)
+            self.end_headers()
+            if send_body:
+                self.wfile.write(body)
+        except ConnectionError:
+            # The client went away before the answer was written.
+            self.close_connection = True
 
     def do_GET(self):
         self.answer(True)

debian-package/src/usr/lib/vpn-router/vpnrouter_web/handler.py

@@ -188,15 +188,19 @@ class Handler(BaseHTTPRequestHandler):
             code = 200
         else:
             body, kind, code = b'Not found\n', 'text/plain; charset=utf-8', 404
-        self.send_response(code)
-        self.send_header('Content-Type', kind)
-        self.send_header('Content-Length', str(len(body)))
-        self.send_header('Cache-Control', 'no-store')
-        for name, value in extra:
-            self.send_header(name, value)
-        self.end_headers()
-        if send_body:
-            self.wfile.write(body)
+        try:
+            self.send_response(code)
+            self.send_header('Content-Type', kind)
+            self.send_header('Content-Length', str(len(body)))
+            self.send_header('Cache-Control', 'no-store')
+            for name, value in extra:
+                self.send_header(name, value)
+            self.end_headers()
+            if send_body:
+                self.wfile.write(body)
+        except ConnectionError:
+            # The client went away before the answer was written.
+            self.close_connection = True
 
     def raw_body(self):
         """The request body's bytes, b'' without one or over BODY_LIMIT."""

debian-package/src/usr/lib/vpn-router/vpnrouter_web/shell.py

@@ -367,11 +367,14 @@ def shell(handler, name):
     def refuse(code, message):
         log(f'shell of {name} from {handler.client()} refused: {message}')
         body = json.dumps({'error': message}).encode() + b'\n'
-        handler.send_response(code)
-        handler.send_header('Content-Type', 'application/json')
-        handler.send_header('Content-Length', str(len(body)))
-        handler.end_headers()
-        handler.wfile.write(body)
+        try:
+            handler.send_response(code)
+            handler.send_header('Content-Type', 'application/json')
+            handler.send_header('Content-Length', str(len(body)))
+            handler.end_headers()
+            handler.wfile.write(body)
+        except ConnectionError:
+            handler.close_connection = True
 
     key = handler.headers.get('Sec-WebSocket-Key', '').strip()
     if handler.headers.get('Upgrade', '').lower() != 'websocket' or 'upgrade' not in handler.headers.get('Connection', '').lower() \
@@ -408,12 +411,21 @@ def shell(handler, name):
     finally:
         os.close(terminal)
     accept = base64.b64encode(hashlib.sha1((key + WEBSOCKET_GUID).encode()).digest()).decode()
-    handler.send_response(101, 'Switching Protocols')
-    handler.send_header('Upgrade', 'websocket')
-    handler.send_header('Connection', 'Upgrade')
-    handler.send_header('Sec-WebSocket-Accept', accept)
-    handler.end_headers()
     handler.close_connection = True
+    try:
+        handler.send_response(101, 'Switching Protocols')
+        handler.send_header('Upgrade', 'websocket')
+        handler.send_header('Connection', 'Upgrade')
+        handler.send_header('Sec-WebSocket-Accept', accept)
+        handler.end_headers()
+    except ConnectionError:
+        # The client went away before the shell opened; the shell started for it is stopped.
+        run('systemctl', 'stop', unit)
+        os.close(master)
+        process.kill()
+        process.wait()
+        log(f'shell of {name} from {handler.client()} ended before it opened: the client closed the connection')
+        return
     client, started, idle = handler.client(), time.monotonic(), options['shell_idle_minutes'] * 60
     log(f'shell of {name} from {client} opened as {account.pw_name} in {unit}')
 

debian-package/src/usr/lib/vpn-router/vpnrouter_web/sites.py

@@ -112,15 +112,19 @@ def site_files(handler, name, relative, query, payload, send_body):
                 return 404, {'error': f'{relative} does not exist'}
             with open(target, 'rb') as handle:
                 size = os.fstat(handle.fileno()).st_size
-                handler.send_response(200)
-                handler.send_header('Content-Type', mimetypes.guess_type(target.name)[0] or 'application/octet-stream')
-                handler.send_header('Content-Length', str(size))
-                handler.send_header('Content-Disposition',
-                                    f"attachment; filename*=UTF-8''{urllib.parse.quote(target.name)}")
-                handler.send_header('Cache-Control', 'no-store')
-                handler.end_headers()
-                if send_body:
-                    shutil.copyfileobj(handle, handler.wfile, vpnrouter_sites.CHUNK)
+                try:
+                    handler.send_response(200)
+                    handler.send_header('Content-Type', mimetypes.guess_type(target.name)[0] or 'application/octet-stream')
+                    handler.send_header('Content-Length', str(size))
+                    handler.send_header('Content-Disposition',
+                                        f"attachment; filename*=UTF-8''{urllib.parse.quote(target.name)}")
+                    handler.send_header('Cache-Control', 'no-store')
+                    handler.end_headers()
+                    if send_body:
+                        shutil.copyfileobj(handle, handler.wfile, vpnrouter_sites.CHUNK)
+                except ConnectionError:
+                    # The client went away before the file was sent.
+                    handler.close_connection = True
             return None
         if handler.command == 'PUT':
             length = handler.headers.get('Content-Length')