NetVM: CDP via userspace relay (REDIRECT to loopback did not establish)

bin/netvm-cdp-relay.py

@@ -0,0 +1,44 @@
+#!/usr/bin/env python3
+"""TCP relay: listen on the netns veth IP:CDP_PORT, forward to 127.0.0.1:CDP_PORT.
+Chromium binds DevTools to loopback only; this exposes it on the veth IP for
+the host (and SSH-forwarded operators). Runs inside the netns. No dependencies.
+Usage: netvm-cdp-relay.py <listen_ip> <listen_port> <target_ip> <target_port>
+"""
+import socket, threading, sys
+
+def pipe(src, dst):
+    try:
+        while True:
+            data = src.recv(65536)
+            if not data:
+                break
+            dst.sendall(data)
+    except OSError:
+        pass
+    finally:
+        for s in (src, dst):
+            try: s.shutdown(socket.SHUT_RDWR)
+            except OSError: pass
+            s.close()
+
+def handle(client, target):
+    try:
+        upstream = socket.create_connection(target, timeout=10)
+    except OSError:
+        client.close()
+        return
+    threading.Thread(target=pipe, args=(client, upstream), daemon=True).start()
+    pipe(upstream, client)
+
+def main():
+    listen_ip, listen_port, target_ip, target_port = sys.argv[1], int(sys.argv[2]), sys.argv[3], int(sys.argv[4])
+    srv = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+    srv.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+    srv.bind((listen_ip, listen_port))
+    srv.listen(16)
+    while True:
+        client, _ = srv.accept()
+        threading.Thread(target=handle, args=(client, (target_ip, target_port)), daemon=True).start()
+
+if __name__ == "__main__":
+    main()