Python实现ping命令
#!/usr/bin/env python# -*- coding: iso-8859-1 -*-"""ping.pyping.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 <lars strand at gnist org>;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, MA02111-1307, USA. Must be running as root, or write a suid-wrapper. Since newer *nix variants, the kernel ignores the setid flags on #! scripts for security reasons RFC792, echo/reply message:0 1 2 30 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 <lars at unik no>;'__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 < int(struct.calcsize("d")): _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 # 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 <= number: 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)) # 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)) 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(, [], [], 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) # fetch pong header pongHeader = pong pongType, pongCode, pongChksum, pongID, pongSeqnr = \ struct.unpack("bbHHh", pongHeader) # fetch starttime from pong starttime = struct.unpack("d", pong) # IPv4 else: # time to live rawPongHop = struct.unpack("s", pong) # convert TTL from 8 bit to 16 bit integer pongHop = int(binascii.hexlify(str(rawPongHop)), 16) # fetch pong header pongHeader = pong pongType, pongCode, pongChksum, pongID, pongSeqnr = \ struct.unpack("bbHHh", pongHeader) # fetch starttime from pong starttime = struct.unpack("d", pong) # 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 < number: 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^2for 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 < number: # 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), str(err)) print "Try `%s --help' for more information." % os.path.basename(sys.argv) sys.exit(1) else: raise Exception, str(err) def _usage(): """Print usage if run as a standalone program """ print """usage: %s 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=sSpecify a timeout, in seconds, before a ping packet is considered 'lost'.-h, --help Display this help and exitReport bugs to lars gnist org""" % os.path.basename(sys.argv)if __name__ == '__main__': """Main loop """ # version control version = string.split(string.split(sys.version)[: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, "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)) # test whether any host given if len(sys.argv) >= 2: node = sys.argv[-1:] # host to be pinged if node == '-' 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
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