python 网络编程——客户端
python 网络编程——客户端
网络通信的基本接口是socket，它扩展了操作系统的基本I/O到网络网络通信。socket可以通过socket()函数来建立，通过connect()函数来连接。得到了socket，可以确定本地和远程端点的IP地址和端口号。socket对不同的协议来说都是一种通用的接口，它可以处理TCP和UDP通信。建立socket需要两步：建立socket对象、连接到远程服务器上
import socket
print "Creating socket"
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) #指明通信类型和协议家族
print "Done!"
print "Connecting to remote host..."
s.connect(("www.baidu.com", 80))
print "Done"
运行结果
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Creating socket
Done!
Connecting to remote host...
Done
查找端口号
通过协议名和端口名查找端口号（unix系统可以在etc/services中找到对应的端口号）
import socket
print "Creating socket"
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
print "Done!"
print "Looking up port number..."
port = socket.getservbyname("http", "tcp")
print port
print "done!"
print "Connecting to remote host..."
s.connect(("www.baidu.com", port))
print "Done!!"
运行结果
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Creating socket
Done!
Looking up port number...
80
done!
Connecting to remote host...
Done!!
从socket获得信息
import socket
print "Creating socket"
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
print "Done!"
print "Looking up port number..."
port = socket.getservbyname("http", "tcp")
print port
print "done!"
print "Connecting to remote host..."
s.connect(("www.baidu.com", port))
print "Done!!"
print "Connected from", s.getsockname() #获得本地机器的ip和端口号（端口号由操作系统随机分配，每次都不一样）
print "Connected to", s.getpeername() #获得连接机器的ip和端口号
一次运行结果
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Creating socket
Done!
Looking up port number...
80
done!
Connecting to remote host...
Done!!
Connected from ('192.168.209.129', 56245)
Connected to ('220.181.112.244', 80)
利用socket通信
socket对象：send()、sendto()、recv()、recvfrom()
文件类对象：read()、write()、readline()
处理错误
import socket, sys
host = sys.argv[1]
textport = sys.argv[2]
filename = sys.argv[3]
try:
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
except socket.error, e:
print "Strange error creating socket: %s" % e
sys.exit(1)
try:
port = int(textport)
except ValueError:
try:
port = socket.getservbyname(textport, 'tcp')
except socket.error, e:
print "Couldn't find your port: %s" % e
sys.exit(1)
try:
s.connect((host, port))
except socket.gaierror, e:
print "Address-related error connecting to server: %s" %e
sys.exit(1)
except socket.error, e:
print "Connection error: %s" %e
sys.exit(1)
try:
s.sendall("GET %s HTTP/1.0\r\n\r\n" % filename)
except socket.error, e:
print "Error sending data: %s" %e
sys.exit(1)
print "---------------------------------------"
while 1:
try:
buf = s.recv(2048)
except socket.error, e:
print "========Error receving data: %s=======" %e
sys.exit(1)
if not len(buf):
break
sys.stdout.write(buf)
print "---------------------------------------"
改进
#coding: utf-8
import socket
import sys
import time
host = sys.argv[1]
textport = sys.argv[2]
filename = sys.argv[3]
try:
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
except socket.error, e:
print "Strange error creating socket: %s" % e
sys.exit(1)
try:
port = int(textport)
except ValueError:
print "ValueError"
try:
port = socket.getservbyname(textport, 'tcp')
except socket.error, e:
print "Couldn't find your port: %s" % e
sys.exit(1)
try:
s.connect((host, port))
except socket.gaierror, e: #主机名不对
print "Address-related error connecting to server: %s" %e
sys.exit(1)
except socket.error, e: #连接远程主机有问题
print "Connection error: %s" %e
sys.exit(1)
print "Sleepping........."
time.sleep(10)
print "Continuing."
try:
s.sendall("GET %s HTTP/1.0\r\n\r\n" % filename)
except socket.error, e:
print "Error sending data: %s" % e
sys.exit(1)
try:
s.shutdown(1)
except socket.error, e:
print "Error sending data (detected by shutdown):%s" % e
sys.exit(1)
print "---------------------------------------"
while 1:
try:
buf = s.recv(2048)
print "try"
except socket.error, e:
print "========Error receving data: %s=======" %e
sys.exit(1)
if not len(buf): #接受的为空
print "breaK"
break
sys.stdout.write(buf)
print "---------------------------------------"
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