[Errno 56]: 如何修复已连接的套接字？

Question

我正在做一个 ICMP ping 程序，但遇到了问题。当我在终端运行程序时，首先输入了 sudo su，这样我就有了管理员权限，因为我们需要使用原始套接字。然后，当我运行程序时，出现了这个错误信息：

sh-3.2# python3 icmp.py
Pinging 31.13.66.112 using Python:

Traceback (most recent call last):
  File "icmp.py", line 149, in <module>
    ping("www.facebook.com")
  File "icmp.py", line 141, in ping
    delay = doOnePing(dest,timeout)
  File "icmp.py", line 123, in doOnePing
    sendOnePing(mySocket,destAddr,myID)
  File "icmp.py", line 111, in sendOnePing
    mySocket.sendto(packet,(destAddr,1))
OSError: [Errno 56] Socket is already connected

这是我正在运行的代码：

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

ICMP_ECHO_REQUEST = 8

def checksum (val):

    csum = 0
    countTo = (len(val) // 2) * 2

    count = 0

    while count < countTo:

        thisVal = val[count+1] * 256 + val[count]

        csum = csum + thisVal

        csum = csum & 0xffffffff

        count = count + 2

    if countTo < len(val):

        csum = csum + val[len(val) - 1]

        csum = csum & 0xffffffff

    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()

        whatReady = select([mySocket],[],[],timeLeft)

        howLongInSelect = (time() - startedSelect)

        if whatReady[0] == []: #Timeout

            return "Request timed out."

        timeReceived = time()

        recPacket, addr = mySocket.recvfrom(1024)

        icmpHeader = recPacket[20:28]

        kind,code,checksum,idNum,sequence = unpack("bbHHh",icmpHeader)

        if idNum == ID:

            sizeofdouble = calcsize("d")

            timeSent = unpack("d",recPacket[28:28+sizeofdouble])[0]

            print(("TYPE: %d CODE: %d CHECKSUM: 0x%08x ID: %d SEQ: %d TIME: %d ms\n" % (kind,code,checksum,idNum,sequence,timeReceived - timeSent)*1000))

        timeLeft = timeLeft - howLongInSelect

        if timeLeft <= 0:

            return "Request timed out."

        else:

            return "Reply from %s successfully." % destAddr

def sendOnePing(mySocket, destAddr, ID):

    myChecksum = 0

    header = pack("bbHHh", ICMP_ECHO_REQUEST, 0, myChecksum, ID, 1)

    data = pack("d",time())

    myChecksum = checksum(header + data)

    if platform == 'darwin':

        myChecksum = htons(myChecksum) & 0xffff

    else:

        myChecksum = htons(myChecksum)

    header = pack("bbHHh", ICMP_ECHO_REQUEST,0,myChecksum,ID,1)

    packet = header + data

    mySocket.sendto(packet,(destAddr,1))

def doOnePing(destAddr,timeout):

    icmp = getprotobyname("icmp")

    mySocket = socket(AF_INET,SOCK_RAW,icmp)

    mySocket.connect((destAddr,80))

    myID = os.getpid() & 0xFFFF

    sendOnePing(mySocket,destAddr,myID)

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

    mySocket.close()

    return delay

def ping(host,timeout = 1):

    dest = gethostbyname(host)

    print("Pinging " + dest + " using Python:")

    print()

    while 1:

        delay = doOnePing(dest,timeout)

        print(delay)

        sleep(1)

    return delay

ping("www.facebook.com")

我们得到了一个实验指导，上面有“骨架”程序的框架，我们需要填补缺失的部分。这是提供骨架代码的实验指导

注意：由于我为了修复之前出现的其他错误而不得不更改一些内容，所以骨架代码和我的程序不会完全匹配。

谢谢大家的帮助，

Tyler

Answer 1

你应该用“bind”，而不是“connect”。然后这个程序你需要以管理员身份运行，比如在Linux或Mac OS上用“sudo python3 icmp.py”来执行。希望这能帮到你。谢谢！

Answer 2

首先，你需要connect这个套接字，也就是告诉它要把数据发送到哪个地址。然后再调用sendto，这时候你又要提供一次对方的地址。即使这两个地址是一样的，套接字也会搞混。

所以，要么就不要connect，要么直接使用send。