drgn/examples/linux/tcp_sock.py

"""List all TCP sockets and their cgroup v2 paths"""

import ipaddress
import os
import socket
import struct

from drgn import Object, cast, container_of
from drgn.helpers import enum_type_to_class
from drgn.helpers.linux import (
    hlist_for_each,
    hlist_nulls_empty,
    sk_fullsock,
    sk_nulls_for_each,
    sk_tcpstate,
)


TcpState = enum_type_to_class(
    prog["TCP_ESTABLISHED"].type_,
    "TcpState",
    exclude=("TCP_MAX_STATES",),
    prefix="TCP_",
)


def inet_sk(sk):
    return cast("struct inet_sock *", sk)


def _ipv4(be32):
    return ipaddress.IPv4Address(struct.pack("I", be32.value_()))


def _ipv6(in6_addr):
    return ipaddress.IPv6Address(struct.pack("IIII", *in6_addr.in6_u.u6_addr32))


def _brackets(ip):
    if ip.version == 4:
        return "{}".format(ip.compressed)
    elif ip.version == 6:
        return "[{}]".format(ip.compressed)
    return ""


def _ip_port(ip, port):
    return "{:>40}:{:<6}".format(_brackets(ip), port)


def _cgroup_path(cgroup):
    cgroup_path = ""

    while cgroup.level > 0:
        cgroup_name = cgroup.kn.name.string_().decode()
        if cgroup_path:
            cgroup_path = os.path.join(cgroup_name, cgroup_path)
        else:
            cgroup_path = cgroup_name

        parent_css = cgroup.self.parent
        if not parent_css:
            break

        cgroup = container_of(parent_css, "struct cgroup", "self")

    return cgroup_path


def _print_sk(sk):
    inet = inet_sk(sk)

    tcp_state = TcpState(sk_tcpstate(sk))

    if sk.__sk_common.skc_family == socket.AF_INET:
        src_ip = _ipv4(sk.__sk_common.skc_rcv_saddr)
        dst_ip = _ipv4(sk.__sk_common.skc_daddr)
    elif sk.__sk_common.skc_family == socket.AF_INET6:
        src_ip = _ipv6(sk.__sk_common.skc_v6_rcv_saddr)
        dst_ip = _ipv6(sk.__sk_common.skc_v6_daddr)
    else:
        return

    src_port = socket.ntohs(inet.inet_sport)
    dst_port = socket.ntohs(sk.__sk_common.skc_dport)

    cgroup_path = ""
    if sk_fullsock(sk):
        cgroup = Object(prog, "struct cgroup", address=sk.sk_cgrp_data.val)
        cgroup_path = _cgroup_path(cgroup)

    print(
        "{:<12} {} {} {}".format(
            tcp_state.name,
            _ip_port(src_ip, src_port),
            _ip_port(dst_ip, dst_port),
            cgroup_path,
        )
    )

    # Uncomment to print whole struct:
    #   print(sk)
    #   print(inet)
    #   print(cgroup)


tcp_hashinfo = prog.object("tcp_hashinfo")

# 1. Iterate over all TCP sockets in TCP_LISTEN state.
for ilb in tcp_hashinfo.listening_hash:
    for pos in hlist_for_each(ilb.head):
        sk = container_of(pos, "struct sock", "__sk_common.skc_node")
        _print_sk(sk)

# 2. And all other TCP sockets.
for i in range(tcp_hashinfo.ehash_mask + 1):
    head = tcp_hashinfo.ehash[i].chain
    if hlist_nulls_empty(head):
        continue
    for sk in sk_nulls_for_each(head):
        _print_sk(sk)