Python Ping，丢包率

Question

我刚刚修改了ping代码。第一个真正的Python程序。

我希望能够弄清楚每次ping中丢失的数据包数量。有没有我可以用来解决这个问题的指南，或者有没有人建议从哪里开始？

谢谢。

from socket import *
import os
import sys
import struct
import time
import select
import binascii

ICMP_ECHO_REQUEST = 8


def checksum(str):
    csum = 0
    countTo = (len(str) / 2) * 2

    count = 0
    while count < countTo:
        thisVal = ord(str[count + 1]) * 256 + ord(str[count])
        csum = csum + thisVal
        csum = csum & 0xffffffffL
        count = count + 2

    if countTo < len(str):
        csum = csum + ord(str[len(str) - 1])
        csum = csum & 0xffffffffL

    csum = (csum >> 16) + (csum & 0xffff)
    csum = csum + (csum >> 16)
    answer = ~csum
    answer = answer & 0xffff
    answer = answer >> 8 | (answer << 8 & 0xff00)
    return answer


def receiveOnePing(mySocket, ID, timeout, destAddr):
    timeLeft = timeout

    while 1:
        startedSelect = time.time()
        whatReady = select.select([mySocket], [], [], timeLeft)
        howLongInSelect = (time.time() - startedSelect)
        if whatReady[0] == []:  # Timeout
            return "Request timed out."

        timeReceived = time.time()
        recPacket, addr = mySocket.recvfrom(1024)

        icmpHeader = recPacket[20:28]
        type, code, checksum, packetID, sequence = struct.unpack("bbHHh", icmpHeader)

        if packetID == ID:
            bytesInDouble = struct.calcsize("d")
            timeSent = struct.unpack("d", recPacket[28:28 + bytesInDouble])[0]
            return timeReceived - timeSent

        timeLeft = timeLeft - howLongInSelect
        if timeLeft <= 0:
            return "Request timed out."


def sendOnePing(mySocket, destAddr, ID):
    # Header is type (8), code (8), checksum (16), id (16), sequence (16)

    myChecksum = 0
    # Make a dummy header with a 0 checksum
    # struct -- Interpret strings as packed binary data
    header = struct.pack("bbHHh", ICMP_ECHO_REQUEST, 0, myChecksum, ID, 1)
    data = struct.pack("d", time.time())
    # Calculate the checksum on the data and the dummy header.
    myChecksum = checksum(header + data)

    # Get the right checksum, and put in the header
    if sys.platform == 'darwin':
        # Convert 16-bit integers from host to network  byte order
        myChecksum = htons(myChecksum) & 0xffff
    else:
        myChecksum = htons(myChecksum)

    header = struct.pack("bbHHh", ICMP_ECHO_REQUEST, 0, myChecksum, ID, 1)
    packet = header + data

    mySocket.sendto(packet, (destAddr, 1))  # AF_INET address must be tuple, not str


# Both LISTS and TUPLES consist of a number of objects
# which can be referenced by their position number within the object.

def doOnePing(destAddr, timeout):
    icmp = getprotobyname("icmp")

    try:
        mySocket = socket(AF_INET, SOCK_RAW, icmp)
    except error, (errno, msg):
        if errno == 1:
            msg = msg + (" - ICMP messages can only be sent when running as root")
            raise error(msg)
        raise

    myID = os.getpid() & 0xFFFF  # Return the current process i

    sendOnePing(mySocket, destAddr, myID)
    delay = receiveOnePing(mySocket, myID, timeout, destAddr)

    mySocket.close()
    return delay


def ping(host, timeout=1):
    # timeout=1 means: If one second goes by without a reply from the server,
    # the client assumes that either the client's ping or the server's pong is lost
    dest = gethostbyname(host)
    print "Pinging " + dest + " using Python:"
    print ""

    # Fill in start
    min = 0
    minNotSet = True
    max = 0
    total = 0

    count = 100
    for i in xrange(count):
        delay = doOnePing(host, timeout)

        if delay == None:
            print "failed. (timeout within %ssec.)" % timeout
        else:
            delay = delay * 1000
            total = total + delay
            if delay > max:
                max = delay
            if delay < min or minNotSet == True:
                minNotSet = False
                min = delay

            #print "get ping in %0.4fms" % delay

    average = total / count
    print "The max is %0.4fms " % max
    print "The min is %0.4fms" % min
    print "The average is %0.4fms" % average

# In addition, calculate the packet loss rate (in percentage).

ping("google.com")