标准ping程序的python实现

#!/usr/bin/env python# -*- coding: iso-8859-1 -*-"""ping.py  ping.py uses the ICMP protocol's mandatory ECHO_REQUEST datagram to elicit an ICMP ECHO_RESPONSE from a host or gateway. Copyright (C) 2004 - Lars Strand   This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.  This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more details.  You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA. Must be running as root, or write a suid-wrapper. Since newer *nix variants, the kernel ignores the set[ug]id flags on #! scripts for security reasons RFC792, echo/reply message:  0                   1                   2                   3  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |     Type      |     Code      |          Checksum             | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |           Identifier          |        Sequence Number        | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |     Data ... +-+-+-+-+-TODO: - do not create socket inside 'while' (but if not: ipv6 won't work) - add support for broadcast/multicast - add support for own payload stringCHANGELOG: DONE --> bugfix from Filip Van Raemdonck mechanix debian org DONE --> add more support for modules (raise instead of sys.exit) DONE --> locale func names DONE --> package def DONE --> some code cleanup """import sysimport osimport structimport arrayimport timeimport selectimport binasciiimport mathimport getoptimport stringimport socket# total size of data (payload)ICMP_DATA_STR = 56  # initial values of header variablesICMP_TYPE = 8ICMP_TYPE_IP6 = 128ICMP_CODE = 0ICMP_CHECKSUM = 0ICMP_ID = 0ICMP_SEQ_NR = 0# Package definitions.__program__   = 'ping'__version__   = '0.5a'__date__      = '2004/15/12'__author__    = 'Lars Strand '__licence__   = 'GPL'__copyright__ = 'Copyright (C) 2004 Lars Strand'def _construct(id, size, ipv6):    """Constructs a ICMP echo packet of variable size    """    # size must be big enough to contain time sent    if size         _error("packetsize to small, must be at least %d" % int(struct.calcsize("d")))        # construct header    if ipv6:        header = struct.pack('BbHHh', ICMP_TYPE_IP6, ICMP_CODE, ICMP_CHECKSUM, \                             ICMP_ID, ICMP_SEQ_NR+id)    else:        header = struct.pack('bbHHh', ICMP_TYPE, ICMP_CODE, ICMP_CHECKSUM, \                             ICMP_ID, ICMP_SEQ_NR+id)    # if size big enough, embed this payload    load = "-- IF YOU ARE READING THIS YOU ARE A NERD! --"        # space for time    size -= struct.calcsize("d")    # construct payload based on size, may be omitted :)    rest = ""    if size > len(load):        rest = load        size -= len(load)    # pad the rest of payload    rest += size * "X"    # pack    data = struct.pack("d", time.time()) + rest    packet = header + data          # ping packet without checksum    checksum = _in_cksum(packet)    # make checksum    # construct header with correct checksum    if ipv6:        header = struct.pack('BbHHh', ICMP_TYPE_IP6, ICMP_CODE, checksum, \                             ICMP_ID, ICMP_SEQ_NR+id)    else:        header = struct.pack('bbHHh', ICMP_TYPE, ICMP_CODE, checksum, ICMP_ID, \                             ICMP_SEQ_NR+id)    # ping packet *with* checksum    packet = header + data     # a perfectly formatted ICMP echo packet    return packetdef _in_cksum(packet):    """THE RFC792 states: 'The 16 bit one's complement of    the one's complement sum of all 16 bit words in the header.'    Generates a checksum of a (ICMP) packet. Based on in_chksum found    in ping.c on FreeBSD.    """    # add byte if not dividable by 2    if len(packet) & 1:                      packet = packet + '\0'    # split into 16-bit word and insert into a binary array    words = array.array('h', packet)     sum = 0    # perform ones complement arithmetic on 16-bit words    for word in words:        sum += (word & 0xffff)     hi = sum >> 16     lo = sum & 0xffff     sum = hi + lo    sum = sum + (sum >> 16)        return (~sum) & 0xffff # return ones complementdef pingNode(alive=0, timeout=1.0, ipv6=0, number=sys.maxint, node=None, \             flood=0, size=ICMP_DATA_STR):    """Pings a node based on input given to the function.    """    # if no node, exit    if not node:        _error("")    # if not a valid host, exit    if ipv6:        if socket.has_ipv6:            try:                info, port = socket.getaddrinfo(node, None)                host = info[4][0]                # do not print ipv6 twice if ipv6 address given as node                if host == node:                     noPrintIPv6adr = 1            except:                _error("cannot resolve %s: Unknow host" % node)        else:            _error("No support for IPv6 on this plattform")    else:    # IPv4        try:            host = socket.gethostbyname(node)        except:            _error("cannot resolve %s: Unknow host" % node)    # trying to ping a network?    if not ipv6:        if int(string.split(host, ".")[-1]) == 0:            _error("no support for network ping")    # do some sanity check    if number == 0:        _error("invalid count of packets to transmit: '%s'" % str(a))    if alive:        number = 1    # Send the ping(s)    start = 1; mint = 999; maxt = 0.0; avg = 0.0    lost = 0; tsum = 0.0; tsumsq = 0.0    # tell the user what we do    if not alive:        if ipv6:            # do not print the ipv6 twice if ip adress given as node            # (it can be to long in term window)            if noPrintIPv6adr == 1:                # add 40 (header) + 8 (icmp header) + payload                print "PING %s : %d data bytes (40+8+%d)" % (str(node), \                                                             40+8+size, size)            else:                # add 40 (header) + 8 (icmp header) + payload                print "PING %s (%s): %d data bytes (40+8+%d)" % (str(node), \                                                                 str(host), 40+8+size, size)        else:            # add 20 (header) + 8 (icmp header) + payload            print "PING %s (%s): %d data bytes (20+8+%d)" % (str(node), str(host), \                                                             20+8+size, size)            # trap ctrl-d and ctrl-c    try:                # send the number of ping packets as given        while start             lost += 1 # in case user hit ctrl-c                        # create the IPv6/IPv4 socket            if ipv6:                # can not create a raw socket if not root or setuid to root                try:                    pingSocket = socket.socket(socket.AF_INET6, socket.SOCK_RAW, \                                               socket.getprotobyname("ipv6-icmp"))                except socket.error, e:                    print "socket error: %s" % e                    _error("You must be root (uses raw sockets)" % os.path.basename(sys.argv[0]))                                # IPv4            else:                # can not create a raw socket if not root or setuid to root                try:                    pingSocket = socket.socket(socket.AF_INET, socket.SOCK_RAW, \                                               socket.getprotobyname("icmp"))                except socket.error, e:                    print "socket error: %s" % e                    _error("You must be root (%s uses raw sockets)" % os.path.basename(sys.argv[0]))                            packet = _construct(start, size, ipv6) # make a ping packet            # send the ping            try:                pingSocket.sendto(packet,(node,1))            except socket.error, e:                _error("socket error: %s" % e)            # reset values            pong = ""; iwtd = []            # wait until there is data in the socket            while 1:                # input, output, exceptional conditions                iwtd, owtd, ewtd = select.select([pingSocket], [], [], timeout)                break # no data and timout occurred             # data on socket - this means we have an answer            if iwtd:  # ok, data on socket                endtime = time.time()  # time packet received                # read data (we only need the header)                pong, address = pingSocket.recvfrom(size+48)                lost -= 1 # in case user hit ctrl-c                # examine packet                # fetch TTL from IP header                if ipv6:                    # since IPv6 header and any extension header are never passed                    # to a raw socket, we can *not* get hoplimit field..                    # I hoped that a socket option would help, but it's not                    # supported:                    #   pingSocket.setsockopt(IPPROTO_IPV6, IPV6_RECVHOPLIMIT, 1)                    # so we can't fetch hoplimit..                    # fetch hoplimit                    #rawPongHop = struct.unpack("c", pong[7])[0]                    # fetch pong header                    pongHeader = pong[0:8]                    pongType, pongCode, pongChksum, pongID, pongSeqnr = \                              struct.unpack("bbHHh", pongHeader)                    # fetch starttime from pong                    starttime = struct.unpack("d", pong[8:16])[0]                # IPv4                else:                    # time to live                    rawPongHop = struct.unpack("s", pong[8])[0]                    # convert TTL from 8 bit to 16 bit integer                    pongHop = int(binascii.hexlify(str(rawPongHop)), 16)                    # fetch pong header                    pongHeader = pong[20:28]                    pongType, pongCode, pongChksum, pongID, pongSeqnr = \                              struct.unpack("bbHHh", pongHeader)                    # fetch starttime from pong                    starttime = struct.unpack("d", pong[28:36])[0]                # valid ping packet received?                if not pongSeqnr == start:                    pong = None            # NO data on socket - timeout waiting for answer            if not pong:                if alive:                    print "no reply from %s (%s)" % (str(node), str(host))                else:                    print "ping timeout: %s (icmp_seq=%d) " % (host, start)                # do not wait if just sending one packet                if number != 1 and start                     time.sleep(flood ^ 1)                start += 1                continue  # lost a packet - try again            triptime  = endtime - starttime # compute RRT            tsum     += triptime            # triptime for all packets (stddev)            tsumsq   += triptime * triptime # triptime^2  for all packets (stddev)            # compute statistic            maxt = max ((triptime, maxt))            mint = min ((triptime, mint))            if alive:                print str(node) + " (" + str(host) +") is alive"            else:                if ipv6:                    # size + 8 = payload + header                    print "%d bytes from %s: icmp_seq=%d time=%.5f ms" % \                          (size+8, host, pongSeqnr, triptime*1000)                else:                    print "%d bytes from %s: icmp_seq=%d ttl=%s time=%.5f ms" % \                          (size+8, host, pongSeqnr, pongHop, triptime*1000)            # do not wait if just sending one packet            if number != 1 and start                 # if flood = 1; do not sleep - just ping                                time.sleep(flood ^ 1) # wait before send new packet            # the last thing to do is update the counter - else the value            # (can) get wrong when computing summary at the end (if user            # hit ctrl-c when pinging)            start += 1            # end ping send/recv while    # if user ctrl-d or ctrl-c    except (EOFError, KeyboardInterrupt):        # if user disrupts ping, it is most likly done before        # the counter get updates - if do not update it here, the        # summary get all wrong.        start += 1        pass    # compute and print som stats    # stddev computation based on ping.c from FreeBSD    if start != 0 or lost > 0:  # do not print stats if 0 packet sent        start -= 1              # since while is '        avg = tsum / start      # avg round trip        vari = tsumsq / start - avg * avg         # %-packet lost        if start == lost:            plost = 100        else:            plost = (lost/start)*100        if not alive:            print "\n--- %s ping statistics ---" % node            print "%d packets transmitted, %d packets received, %d%% packet loss" % \                  (start, start-lost, plost)            # don't display summary if 100% packet-loss            if plost != 100:                print "round-trip min/avg/max/stddev = %.3f/%.3f/%.3f/%.3f ms" % \                      (mint*1000, (tsum/start)*1000, maxt*1000, math.sqrt(vari)*1000)    pingSocket.close()    def _error(err):    """Exit if running standalone, else raise an exception    """    if __name__ == '__main__':        print "%s: %s" % (os.path.basename(sys.argv[0]), str(err))        print "Try `%s --help' for more information." % os.path.basename(sys.argv[0])        sys.exit(1)    else:        raise Exception, str(err)    def _usage():    """Print usage if run as a standalone program    """    print """usage: %s [OPTIONS] HOSTSend ICMP ECHO_REQUEST packets to network hosts.Mandatory arguments to long options are mandatory for short options too.  -c, --count=N    Stop after sending (and receiving) 'N' ECHO_RESPONSE                   packets.  -s, --size=S     Specify the number of data bytes to be sent. The default                   is 56, which translates into 64 ICMP data bytes when                   combined with the 8 bytes of ICMP header data.  -f, --flood      Flood ping. Outputs packets as fast as they come back. Use                   with caution!  -6, --ipv6       Ping using IPv6.  -t, --timeout=s  Specify a timeout, in seconds, before a ping packet is                   considered 'lost'.  -h, --help       Display this help and exitReport bugs to lars [at] gnist org""" % os.path.basename(sys.argv[0])if __name__ == '__main__':    """Main loop    """    # version control    version = string.split(string.split(sys.version)[0][:3], ".")    if map(int, version)         _error("You need Python ver 2.3 or higher to run!")    try:        # opts = arguments recognized,        # args = arguments NOT recognized (leftovers)        opts, args = getopt.getopt(sys.argv[1:-1], "hat:6c:fs:", \                                   ["help", "alive", "timeout=", "ipv6", \                                    "count=", "flood", "packetsize="])    except getopt.GetoptError:        # print help information and exit:        _error("illegal option(s) -- " + str(sys.argv[1:]))    # test whether any host given    if len(sys.argv) >= 2:        node = sys.argv[-1:][0]   # host to be pinged        if node[0] == '-' or node == '-h' or node == '--help' :              _usage()    else:        _error("No arguments given")    if args:        _error("illegal option -- %s" % str(args))            # default variables    alive = 0; timeout = 1.0; ipv6 = 0; count = sys.maxint;    flood = 0; size = ICMP_DATA_STR    # run through arguments and set variables    for o, a in opts:        if o == "-h" or o == "--help":    # display help and exit            _usage()            sys.exit(0)        if o == "-t" or o == "--timeout": # timeout before "lost"            try:                timeout = float(a)            except:                _error("invalid timout: '%s'" % str(a))        if o == "-6" or o == "--ipv6":    # ping ipv6            ipv6 = 1        if o == "-c" or o == "--count":   # how many pings?            try:                count = int(a)            except:                _error("invalid count of packets to transmit: '%s'" % str(a))        if o == "-f" or o == "--flood":   # no delay between ping send            flood = 1        if o == "-s" or o == "--packetsize":  # set the ping payload size            try:                size = int(a)            except:                _error("invalid packet size: '%s'" % str(a))        # just send one packet and say "it's alive"        if o == "-a" or o == "--alive":               alive = 1    # here we send    pingNode(alive=alive, timeout=timeout, ipv6=ipv6, number=count, \             node=node, flood=flood, size=size)    # if we made it this far, do a clean exit    sys.exit(0)### end