Python实现PING命令的示例代码
作者:Small_Teenager
一、PING简介
PING(Packet Internet Grope),也称因特网包探索器。PING使用ICMP回送(ECHO)请求和回送(ECHO)应答报文,一般用于测试网络连通性,统计往返时间、丢包率等。PING UNIX命令格式如下:
ping [ - Rdfnqrv ] [ - c count ] [ - i wait ] [ - l preload ] [ - p pattern ] [ - s packetsize ] host
如果目标主机正在运行并连在网络上,它就会对ICMP ECHO请求报文进行应答。每个ICMP ECHO请求报文包含一个IP和ICMP报文收不,后紧跟一个timeval结构,以及用来填充这个报文的填充字节。
缺省情况下,PING连续发送ICMP ECHO请求报文,直到收到中断信号(Ctrl - C)。PING命令每秒发送一个报文,并且在程序结束是显示一个简要总结。PING命令在程序超时或接收到中断信号时结束。host参数可以是有效的主机名或IP地址。
报文结构如下:
二、代码实现
# encoding:utf-8 import time import struct import socket import select def chesksum(data): n = len(data) m = n % 2 sum = 0 for i in range(0, n - m ,2): sum += (data[i]) + ((data[i+1]) << 8)#传入data以每两个字节(十六进制)通过ord转十进制,第一字节在低位,第二个字节在高位 if m: sum += (data[-1]) #将高于16位与低16位相加 sum = (sum >> 16) + (sum & 0xffff) sum += (sum >> 16) #如果还有高于16位,将继续与低16位相加 answer = ~sum & 0xffff # 主机字节序转网络字节序列(参考小端序转大端序) answer = answer >> 8 | (answer << 8 & 0xff00) return answer def request_ping(data_type,data_code,data_checksum,data_ID,data_Sequence,payload_body): # 把字节打包成二进制数据 icmp_packet = struct.pack('>BBHHH32s',data_type,data_code,data_checksum,data_ID,data_Sequence,payload_body) icmp_chesksum = chesksum(icmp_packet) #获取校验和 # 把校验和传入,再次打包 icmp_packet = struct.pack('>BBHHH32s',data_type,data_code,icmp_chesksum,data_ID,data_Sequence,payload_body) return icmp_packet def raw_socket(dst_addr,icmp_packet): ''' 连接套接字,并将数据发送到套接字 ''' #实例化一个socket对象,ipv4,原套接字,分配协议端口 rawsocket = socket.socket(socket.AF_INET,socket.SOCK_RAW,socket.getprotobyname("icmp")) #记录当前请求时间 send_request_ping_time = time.time() #发送数据到网络 rawsocket.sendto(icmp_packet,(dst_addr,80)) #返回数据 return send_request_ping_time,rawsocket,dst_addr def reply_ping(send_request_ping_time,rawsocket,data_Sequence,timeout = 2): while True: #开始时间 started_select = time.time() #实例化select对象,可读rawsocket,可写为空,可执行为空,超时时间 what_ready = select.select([rawsocket], [], [], timeout) #等待时间 wait_for_time = (time.time() - started_select) #没有返回可读的内容,判断超时 if what_ready[0] == []: # Timeout return -1 #记录接收时间 time_received = time.time() #设置接收的包的字节为1024 received_packet, addr = rawsocket.recvfrom(1024) #获取接收包的icmp头 #print(icmpHeader) icmpHeader = received_packet[20:28] #反转编码 type, code, checksum, packet_id, sequence = struct.unpack( ">BBHHH", icmpHeader ) if type == 0 and sequence == data_Sequence: return time_received - send_request_ping_time #数据包的超时时间判断 timeout = timeout - wait_for_time if timeout <= 0: return -1 def dealtime(dst_addr,sumtime,shorttime,longtime,accept,i,time): sumtime += time print(sumtime) if i == 4: print("{0}的Ping统计信息:".format(dst_addr)) print("数据包:已发送={0},接收={1},丢失={2}({3}%丢失),\n往返行程的估计时间(以毫秒为单位):\n\t最短={4}ms,最长={5}ms,平均={6}ms".format(i+1,accept,i+1-accept,(i+1-accept)/(i+1)*100,shorttime,longtime,sumtime)) def ping(host): send, accept, lost = 0, 0, 0 sumtime, shorttime, longtime, avgtime = 0, 1000, 0, 0 #TODO icmp数据包的构建 data_type = 8 # ICMP Echo Request data_code = 0 # must be zero data_checksum = 0 # "...with value 0 substituted for this field..." data_ID = 0 #Identifier data_Sequence = 1 #Sequence number payload_body = b'abcdefghijklmnopqrstuvwabcdefghi' #data # 将主机名转ipv4地址格式,返回以ipv4地址格式的字符串,如果主机名称是ipv4地址,则它将保持不变 dst_addr = socket.gethostbyname(host) print("正在 Ping {0} [{1}] 具有 32 字节的数据:".format(host,dst_addr)) for i in range(0,4): send = i + 1 #请求ping数据包的二进制转换 icmp_packet = request_ping(data_type,data_code,data_checksum,data_ID,data_Sequence + i,payload_body) #连接套接字,并将数据发送到套接字 send_request_ping_time,rawsocket,addr = raw_socket(dst_addr,icmp_packet) #数据包传输时间 times = reply_ping(send_request_ping_time,rawsocket,data_Sequence + i) if times > 0: print("来自 {0} 的回复: 字节=32 时间={1}ms".format(addr,int(times*1000))) accept += 1 return_time = int(times * 1000) sumtime += return_time if return_time > longtime: longtime = return_time if return_time < shorttime: shorttime = return_time time.sleep(0.7) else: lost += 1 print("请求超时。") if send == 4: print("{0}的Ping统计信息:".format(dst_addr)) print("\t数据包:已发送={0},接收={1},丢失={2}({3}%丢失),\n往返行程的估计时间(以毫秒为单位):\n\t最短={4}ms,最长={5}ms,平均={6}ms".format( i + 1, accept, i + 1 - accept, (i + 1 - accept) / (i + 1) * 100, shorttime, longtime, sumtime/send)) if __name__ == "__main__": i = input("请输入要ping的主机或域名\n") ping(i)
三、结果显示
D:\Miniconda3\python.exe D:/网络协议分析与设计/实验/ping/ping.py
请输入要ping的主机或域名
www.baidu.com
正在 Ping www.baidu.com [14.215.177.39] 具有 32 字节的数据:
来自 14.215.177.39 的回复: 字节=32 时间=34ms
来自 14.215.177.39 的回复: 字节=32 时间=26ms
来自 14.215.177.39 的回复: 字节=32 时间=32ms
来自 14.215.177.39 的回复: 字节=32 时间=28ms
14.215.177.39的Ping统计信息:
数据包:已发送=4,接收=4,丢失=0(0.0%丢失),
往返行程的估计时间(以毫秒为单位):
最短=26ms,最长=34ms,平均=30.0ms
Process finished with exit code 0
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