计算机网络自顶向下方法 第四章 套接字编程作业 ICMP ping 答案
https://github.com/jzplp/Computer-Network-A-Top-Down-Approach-Answer
作业5： ICMP ping
- 官方文档 文档翻译
- 编程作业答案
# 对代码进行了少部分改动
import socket
import os
import sys
import struct
import time
import select
import binascii
ICMP_ECHO_REQUEST = 8
def checksum(strCheck):
csum = 0
countTo = (len(strCheck) / 2) * 2
count = 0
while count < countTo:
thisVal = strCheck[count + 1] * 256 + strCheck[count]
csum = csum + thisVal
csum = csum & 0xffffffff
count = count + 2
if countTo < len(strCheck):
csum = csum + strCheck[len(strCheck) - 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.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)
header = recPacket[20:28]
header_type, header_code, header_checksum, header_packet_ID, header_sequence = struct.unpack("bbHHh", header)
if(header_type != 0 or header_code != 0 or header_packet_ID != ID or header_sequence != 1):
return "Receive error."
timeLeft = timeLeft - howLongInSelect
if timeLeft <= 0:
return "Request timed out."
return timeLeft
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.
# 创建一个带有0校验和的伪头。
# struct -- Interpret strings as packed binary data
# struct-将字符串解释为打包的二进制数据
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.
# 计算数据和虚拟头的校验和。
myChecksum = checksum(header + data)
# Get the right checksum, and put in the header
if sys.platform == 'darwin':
myChecksum = socket.htons(myChecksum) & 0xffff
# Convert 16-bit integers from host to network byte order.
# 将主机的16位整数转换为网络字节顺序。
else:
myChecksum = socket.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 = socket.getprotobyname("icmp")
mySocket = socket.socket(socket.AF_INET, socket.SOCK_RAW, icmp)
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
# timeout = 1 表示：如果一秒钟没有收到服务器的答复，则客户端会认为客户端的ping或服务器的pong丢失了
dest = socket.gethostbyname(host)
print("Pinging " + dest + " using Python:")
print("")
# Send ping requests to a server separated by approximately one second
# 将ping请求发送到间隔约一秒钟的服务器
while 1:
delay = doOnePing(dest, timeout)
print(1 - delay)
time.sleep(1) # one second
ping("baidu.com")- 可选练习1答案
# 对代码进行了少部分改动
import socket
import os
import sys
import struct
import time
import select
import binascii
ICMP_ECHO_REQUEST = 8
def checksum(strCheck):
csum = 0
countTo = (len(strCheck) / 2) * 2
count = 0
while count < countTo:
thisVal = strCheck[count + 1] * 256 + strCheck[count]
csum = csum + thisVal
csum = csum & 0xffffffff
count = count + 2
if countTo < len(strCheck):
csum = csum + strCheck[len(strCheck) - 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.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)
header = recPacket[20:28]
header_type, header_code, header_checksum, header_packet_ID, header_sequence = struct.unpack("bbHHh", header)
if(header_type != 0 or header_code != 0 or header_packet_ID != ID or header_sequence != 1):
return "Receive error."
timeLeft = timeLeft - howLongInSelect
if timeLeft <= 0:
return "Request timed out."
return 1 - timeLeft
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.
# 创建一个带有0校验和的伪头。
# struct -- Interpret strings as packed binary data
# struct-将字符串解释为打包的二进制数据
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.
# 计算数据和虚拟头的校验和。
myChecksum = checksum(header + data)
# Get the right checksum, and put in the header
if sys.platform == 'darwin':
myChecksum = socket.htons(myChecksum) & 0xffff
# Convert 16-bit integers from host to network byte order.
# 将主机的16位整数转换为网络字节顺序。
else:
myChecksum = socket.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 = socket.getprotobyname("icmp")
mySocket = socket.socket(socket.AF_INET, socket.SOCK_RAW, icmp)
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
# timeout = 1 表示：如果一秒钟没有收到服务器的答复，则客户端会认为客户端的ping或服务器的pong丢失了
dest = socket.gethostbyname(host)
print("正在 Ping", host, "[", dest, "] :")
# Send ping requests to a server separated by approximately one second
# 将ping请求发送到间隔约一秒钟的服务器
num = 4
lost = 0
delayList = []
for i in range(num):
delay = doOnePing(dest, timeout)
if(type(delay) == str):
print(delay)
lost = lost + 1
continue
delay = int(delay * 1000)
delayList.append(delay)
print("来自", dest, "的回复: 时间=", delay, "ms")
time.sleep(1) # one second
print(dest, "的 Ping 统计信息:")
print("\t数据包: 已发送 =", num, "，已接收 =", num - lost, "，丢失 =", lost, "(", lost/num * 100, "% 丢失)")
if(delayList):
print("往返行程的估计时间(以毫秒为单位):")
print("\t最短 =", min(delayList), "ms，最长 =", max(delayList), "ms，平均 =", sum(delayList)/len(delayList), "ms")
ping("qq.com")- 可选练习2答案
# 对代码进行了少部分改动
import socket
import os
import sys
import struct
import time
import select
import binascii
ICMP_ECHO_REQUEST = 8
def checksum(strCheck):
csum = 0
countTo = (len(strCheck) / 2) * 2
count = 0
while count < countTo:
thisVal = strCheck[count + 1] * 256 + strCheck[count]
csum = csum + thisVal
csum = csum & 0xffffffff
count = count + 2
if countTo < len(strCheck):
csum = csum + strCheck[len(strCheck) - 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.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)
header = recPacket[20:28]
header_type, header_code, header_checksum, header_packet_ID, header_sequence = struct.unpack("bbHHh", header)
if(header_type != 0 or header_code != 0 or header_packet_ID != ID or header_sequence != 1):
if(header_type == 3 and header_code == 0):
return "目的网络不可达"
if(header_type == 3 and header_code == 1):
return "目的主机不可达"
if(header_type == 3 and header_code == 2):
return "目的协议不可达"
if(header_type == 3 and header_code == 3):
return "目的端口不可达"
if(header_type == 3 and header_code == 6):
return "目的网络未知"
if(header_type == 3 and header_code == 7):
return "目的主机未知"
if(header_type == 4 and header_code == 0):
return "源抑制"
if(header_type == 12 and header_code == 0):
return "IP首部损坏"
return "Request error."
timeLeft = timeLeft - howLongInSelect
if timeLeft <= 0:
return "Request timed out."
return 1 - timeLeft
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.
# 创建一个带有0校验和的伪头。
# struct -- Interpret strings as packed binary data
# struct-将字符串解释为打包的二进制数据
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.
# 计算数据和虚拟头的校验和。
myChecksum = checksum(header + data)
# Get the right checksum, and put in the header
if sys.platform == 'darwin':
myChecksum = socket.htons(myChecksum) & 0xffff
# Convert 16-bit integers from host to network byte order.
# 将主机的16位整数转换为网络字节顺序。
else:
myChecksum = socket.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 = socket.getprotobyname("icmp")
mySocket = socket.socket(socket.AF_INET, socket.SOCK_RAW, icmp)
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
# timeout = 1 表示：如果一秒钟没有收到服务器的答复，则客户端会认为客户端的ping或服务器的pong丢失了
dest = socket.gethostbyname(host)
print("正在 Ping", host, "[", dest, "] :")
# Send ping requests to a server separated by approximately one second
# 将ping请求发送到间隔约一秒钟的服务器
num = 4
lost = 0
delayList = []
for i in range(num):
delay = doOnePing(dest, timeout)
if(type(delay) == str):
print(delay)
lost = lost + 1
continue
delay = int(delay * 1000)
delayList.append(delay)
print("来自", dest, "的回复: 时间=", delay, "ms")
time.sleep(1) # one second
print(dest, "的 Ping 统计信息:")
print("\t数据包: 已发送 =", num, "，已接收 =", num - lost, "，丢失 =", lost, "(", lost/num * 100, "% 丢失)")
if(delayList):
print("往返行程的估计时间(以毫秒为单位):")
print("\t最短 =", min(delayList), "ms，最长 =", max(delayList), "ms，平均 =", sum(delayList)/len(delayList), "ms")
ping("www.12306.cn")