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#!/usr/bin/env python3
""" Alter the socket options of a running process """
import argparse
import subprocess
import logging
import pprint
SO_SOCKET = 1
SO_TCP = 6
SO_KEEPALIVE = 9
TCP_KEEPIDLE = 4
TCP_KEEPINTVL = 5
TCP_KEEPCNT = 6
MSG_NOSIGNAL = 0x4000
def _get_commands_enable_disable_keepalive(sockfd: int, enable: bool, **kwargs):
""" Return GDB instructions to enable or disable keepalive on a given socket """
return (
"set $rsp -= sizeof(int)",
f"set {{int}}$rsp = {1 if enable else 0}",
f"call (int)setsockopt({sockfd}, {SO_SOCKET}, {SO_KEEPALIVE}, $rsp, sizeof(int))",
"set $rsp += sizeof(int)",
)
def _get_commands_change_tcp_option(sockfd: int, value: int, param: int, **kwargs):
""" Return GDB instructions to change a given TCP option on a given socket """
return (
"set $rsp -= sizeof(int)",
f"set {{int}}$rsp = {value}",
f"call (int)setsockopt({sockfd}, {SO_TCP}, {param}, $rsp, sizeof(int))",
"set $rsp += sizeof(int)",
)
def get_commands_send_data(sockfd: int, data: str, **kwargs):
""" Return GDB instructions to send raw data through a socket """
if '"' in data or "\n" in data:
raise ValueError("Double-quotes and newlines are not supported")
return [f'call (int)send({sockfd}, "{data}", {len(data)}, {MSG_NOSIGNAL})']
def get_commands_enable_keepalive(**kwargs):
""" Return GDB commands to enable keepalive on a given socket """
return _get_commands_enable_disable_keepalive(enable=True, **kwargs)
def get_commands_disable_keepalive(**kwargs):
""" Return GDB commands to disable keepalive on a given socket """
return _get_commands_enable_disable_keepalive(enable=False, **kwargs)
def get_commands_change_keepalive_time(**kwargs):
""" Return GDB commands to set the TCP keepalive time on a given socket """
return _get_commands_change_tcp_option(param=TCP_KEEPIDLE, **kwargs)
def get_commands_change_keepalive_intvl(**kwargs):
""" Return GDB commands to set the TCP keepalive interval on a given socket """
return _get_commands_change_tcp_option(param=TCP_KEEPINTVL, **kwargs)
def get_commands_change_keepalive_count(**kwargs):
""" Return GDB commands to set the TCP keepalive count on a given socket """
return _get_commands_change_tcp_option(param=TCP_KEEPCNT, **kwargs)
def main(args):
numeric_level = getattr(logging, args["loglevel"].upper(), None)
if not isinstance(numeric_level, int):
raise ValueError(f"Invalid log level: {args['loglevel']}")
logging.basicConfig(level=numeric_level)
cmd = ["gdb", "--pid", str(args["pid"]), "--batch-silent"]
gdb_cmds = list()
gdb_cmds.extend(args["command"](**args))
logging.debug("gdb commands: %s", pprint.pformat(gdb_cmds))
cmd.extend(map(lambda gdb_cmd: f"--eval-command={gdb_cmd}", gdb_cmds))
logging.debug("Executing: %s", pprint.pformat(cmd))
subprocess.run(cmd, check=True)
if __name__ == "__main__":
parser = argparse.ArgumentParser()
parser.add_argument("--pid", type=int, required=True,
help="PID of the running process to alter")
parser.add_argument("--sockfd", type=int, required=True,
help="Socket file-descriptor number to alter")
parser.add_argument("--loglevel", default="info",
help="Change log level")
subparsers = parser.add_subparsers(help="Command")
# Enable TCP keepalive
subparser = subparsers.add_parser("enable-keepalive", aliases=["enable-ka"],
help="Enable TCP keepalive on the specified socket")
subparser.set_defaults(command=get_commands_enable_keepalive)
# Disable TCP keepalive
subparser = subparsers.add_parser("disable-keepalive", aliases=["disable-ka"],
help="Disable TCP keepalive on the specified socket")
subparser.set_defaults(command=get_commands_disable_keepalive)
# Set TCP keepalive time
subparser = subparsers.add_parser("set-keepalive-time", aliases=["set-ka-time"],
help="Set TCP keepalive time (i.e. net.ipv4.tcp_keepalive_time)")
subparser.add_argument("value", type=int)
subparser.set_defaults(command=get_commands_change_keepalive_time)
# Set TCP keepalive interval
subparser = subparsers.add_parser("set-keepalive-interval", aliases=["set-ka-intvl", "set-ka-interval"],
help="Set TCP keepalive interval (i.e. net.ipv4.tcp_keepalive_intvl)")
subparser.add_argument("value", type=int)
subparser.set_defaults(command=get_commands_change_keepalive_intvl)
# Set TCP keepalive count
subparser = subparsers.add_parser("set-keepalive-count", aliases=["set-ka-count"],
help="Set TCP keepalive count (i.e. net.ipv4.tcp_keepalive_probes)")
subparser.add_argument("value", type=int)
subparser.set_defaults(command=get_commands_change_keepalive_count)
# Send data
subparser = subparsers.add_parser("send-data", aliases=["send"],
help="Send data through the socket")
subparser.add_argument("data", help="Raw data")
subparser.set_defaults(command=get_commands_send_data)
main(vars(parser.parse_args()))
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