python implementation of getpeereid() and getpeerpid() for darwin

get_unix_socket_peer_info.py

#!/usr/bin/python
# vim: set ts=4 sw=4 et ai si:

import socket
import struct

def getpeereid(sock):
    LOCAL_PEERCRED = 0x001
    fmt = struct.Struct('2Ih16I') # see /usr/include/sys/ucred.h struct xucred
    res = tuple(fmt.unpack(sock.getsockopt(0, LOCAL_PEERCRED, fmt.size)))
    return (res[1], res[3:3+res[2]]) # return peer's uid and gids

def getpeerpid(sock):
    LOCAL_PEERPID = 0x002
    fmt = struct.Struct('I')
    res = fmt.unpack(sock.getsockopt(0, LOCAL_PEERPID, fmt.size))
    return (res[0]) # return peer's pid

path = '/var/run/mDNSResponder'
sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
sock.connect(path)
uid, gids = getpeereid(sock)
pid = getpeerpid(sock)
print("socket: %s" % path)
print("peer uid = %s" % uid)
print("peer pid = %s" % pid)