1#!/usr/bin/env python3 2# SPDX-License-Identifier: GPL-2.0 3 4""" 5tdc_gso.py - send a UDP GSO datagram 6 7Copyright (C) 2026 Xingquan Liu <b1n@b1n.io> 8""" 9 10import argparse 11import socket 12import struct 13import sys 14 15UDP_MAX_SEGMENTS = 1 << 7 16 17 18parser = argparse.ArgumentParser(description="UDP GSO datagram sender") 19parser.add_argument("src", help="source IPv4 address") 20parser.add_argument("dst", help="destination IPv4 address") 21parser.add_argument("port", type=int, help="destination UDP port") 22parser.add_argument("gso_size", type=int, help="UDP GSO segment payload size") 23parser.add_argument("payload_len", type=int, help="total UDP payload length") 24args = parser.parse_args() 25 26if args.gso_size <= 0 or args.gso_size > 0xFFFF: 27 parser.error("gso_size must fit in an unsigned 16-bit integer") 28if args.payload_len <= args.gso_size: 29 parser.error("payload_len must be larger than gso_size") 30if args.payload_len > args.gso_size * UDP_MAX_SEGMENTS: 31 parser.error("payload_len exceeds UDP_MAX_SEGMENTS") 32 33SOL_UDP = getattr(socket, "SOL_UDP", socket.IPPROTO_UDP) 34UDP_SEGMENT = getattr(socket, "UDP_SEGMENT", 103) 35 36sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) 37sock.bind((args.src, 0)) 38 39payload = b"b" * args.payload_len 40cmsg = [(SOL_UDP, UDP_SEGMENT, struct.pack("=H", args.gso_size))] 41 42sent = sock.sendmsg([payload], cmsg, 0, (args.dst, args.port)) 43sys.exit(sent != len(payload)) 44