Python 使用指定的网卡发送HTTP请求的实例

2023-08-16 20:25:04 65

需求:一台机器上有多个网卡,如何访问指定的URL时使用指定的网卡发送数据呢?

$curl--interfaceeth0www.baidu.com#curlinterface可以指定网卡

阅读urllib.py的源码,追述到open_http–>httplib.HTTP–>httplib.HTTP._connection_class=HTTPConnection

HTTPConnection在创建的时候会指定一个source_address.

HTTPConnection.connect时调用HTTPConnection._create_connection=socket.create_connection

#先看一下本地网卡信息
$ifconfig
lo0:flags=8049mtu16384
options=3
inet6::1prefixlen128
inet127.0.0.1netmask0xff000000
inet6fe80::1%lo0prefixlen64scopeid0x1
nd6options=1
en0:flags=8863mtu1500
etherc8:e0:eb:17:3a:73
inet6fe80::cae0:ebff:fe17:3a73%en0prefixlen64scopeid0x4
inet192.168.20.2netmask0xffffff00broadcast192.168.20.255
nd6options=1
media:autoselect
status:active
en1:flags=8863mtu1500
options=4
ether0c:5b:8f:27:9a:64
inet6fe80::e5b:8fff:fe27:9a64%en8prefixlen64scopeid0xa
inet192.168.8.100netmask0xffffff00broadcast192.168.8.255
nd6options=1
media:autoselect(100baseTX)
status:active

可以看到en0和en1,这两块网卡都可以访问公网.lo0是本地回环.

直接修改socket.py做测试.

defcreate_connection(address,timeout=_GLOBAL_DEFAULT_TIMEOUT,
source_address=None):
"""If*source_address*issetitmustbeatupleof(host,port)
forthesockettobindasasourceaddressbeforemakingtheconnection.
Anhostof''orport0tellstheOStousethedefault.
source_address如果设置,必须是传递元组(host,port),默认是("",0)
"""

host,port=address
err=None
forresingetaddrinfo(host,port,0,SOCK_STREAM):
af,socktype,proto,canonname,sa=res
sock=None
try:
sock=socket(af,socktype,proto)
#sock.bind(("192.168.20.2",0))#en0
#sock.bind(("192.168.8.100",0))#en1
#sock.bind(("127.0.0.1",0))#lo0
iftimeoutisnot_GLOBAL_DEFAULT_TIMEOUT:
sock.settimeout(timeout)
ifsource_address:
print"socketbindsource_address:%s"%source_address
sock.bind(source_address)
sock.connect(sa)
returnsock

excepterroras_:
err=_
ifsockisnotNone:
sock.close()
iferrisnotNone:
raiseerr
else:
raiseerror("getaddrinforeturnsanemptylist")

参考说明文档,直接分三次绑定不通网卡的IP地址,端口设置为0.

#测试en0
$python-c'importurllibasu;printu.urlopen("http://ip.haschek.at").read()'
.148.245.16

#测试en1
$python-c'importurllibasu;printu.urlopen("http://ip.haschek.at").read()'
.94.115.227

#测试lo0
$python-c'importurllibasu;printu.urlopen("http://ip.haschek.at").read()'
Traceback(mostrecentcalllast):
File"",line1,in
File"/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/urllib.py",line87,inurlopen
returnopener.open(url)
File"/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/urllib.py",line213,inopen
returngetattr(self,name)(url)
File"/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/urllib.py",line350,inopen_http
h.endheaders(data)
File"/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/httplib.py",line1049,inendheaders
self._send_output(message_body)
File"/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/httplib.py",line893,in_send_output
self.send(msg)
File"/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/httplib.py",line855,insend
self.connect()
File"/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/httplib.py",line832,inconnect
self.timeout,self.source_address)
File"/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/socket.py",line578,increate_connection
raiseerr
IOError:[Errnosocketerror][Errno49]Can'tassignrequestedaddress

测试通过,说明在多网卡情况下,创建socket时绑定某块网卡的IP就可以,端口需要设置为0.如果端口不设置为0,第二次请求时,可以看到抛异常,端口被占用.

Traceback(mostrecentcalllast):
File"",line1,in
File"/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/urllib.py",line87,inurlopen
returnopener.open(url)
File"/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/urllib.py",line213,inopen
returngetattr(self,name)(url)
File"/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/urllib.py",line350,inopen_http
h.endheaders(data)
File"/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/httplib.py",line1049,inendheaders
self._send_output(message_body)
File"/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/httplib.py",line893,in_send_output
self.send(msg)
File"/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/httplib.py",line855,insend
self.connect()
File"/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/httplib.py",line832,inconnect
self.timeout,self.source_address)
File"/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/socket.py",line577,increate_connection
raiseerr
IOError:[Errnosocketerror][Errno48]Addressalreadyinuse

如果是在项目中,只需要把socket.create_connection这个函数的形参source_address设置为对应网卡的(IP,0)就可以.

#test-interface_urllib.py
importsocket
importurllib,urllib2

_create_socket=socket.create_connection

SOURCE_ADDRESS=("127.0.0.1",0)
#SOURCE_ADDRESS=("172.28.153.121",0)
#SOURCE_ADDRESS=("172.16.30.41",0)

defcreate_connection(*args,**kwargs):
in_args=False
iflen(args)>=3:
args=list(args)
args[2]=SOURCE_ADDRESS
args=tuple(args)
in_args=True
ifnotin_args:
kwargs["source_address"]=SOURCE_ADDRESS
print"args",args
print"kwargs",str(kwargs)
return_create_socket(*args,**kwargs)

socket.create_connection=create_connection

printurllib.urlopen("http://ip.haschek.at").read()

通过测试,可以发现已经可以通过制定的网卡发送数据,并且IP地址对应网卡分配的IP.

问题,爬虫经常使用requests,requests是否支持呢.通过测试,可以发现,requests并没有使用python内置的socket模块.

看源码,requests是如果创建的socket连接呢.方法和查看urllib创建socket的方式一样.具体就不写了.

因为我用的是python2.7,所以可以定位到requests使用的socket模块是urllib3.utils.connection的.

修改方法和urllib相差不大.

importurllib3.connection
_create_socket=urllib3.connection.connection.create_connection
#pass

urllib3.connection.connection.create_connection=create_connection
#pass

运行后,可能会抛出异常.requests.exceptions.ConnectionError:Maxretriesexceededwith..Invalidargument

这个异常不是每次出现,跟IP段有关系,跳转递归层数太多导致,只需要将kwargs中的socket_options去掉即可.127.0.0.1肯定会出异常.

importsocket
importurllib
importurllib2
importurllib3.connection

importrequestsasreq

_default_create_socket=socket.create_connection
_urllib3_create_socket=urllib3.connection.connection.create_connection


SOURCE_ADDRESS=("127.0.0.1",0)
#SOURCE_ADDRESS=("172.28.153.121",0)
#SOURCE_ADDRESS=("172.16.30.41",0)

defdefault_create_connection(*args,**kwargs):
try:
delkwargs["socket_options"]
except:
pass
in_args=False
iflen(args)>=3:
args=list(args)
args[2]=SOURCE_ADDRESS
args=tuple(args)
in_args=True
ifnotin_args:
kwargs["source_address"]=SOURCE_ADDRESS
print"args",args
print"kwargs",str(kwargs)
return_default_create_socket(*args,**kwargs)

defurllib3_create_connection(*args,**kwargs):
in_args=False
iflen(args)>=3:
args=list(args)
args[2]=SOURCE_ADDRESS
in_args=True
args=tuple(args)
ifnotin_args:
kwargs["source_address"]=SOURCE_ADDRESS
print"args",args
print"kwargs",str(kwargs)
return_urllib3_create_socket(*args,**kwargs)

socket.create_connection=default_create_connection
#因为偶尔会出问题,所以使用默认的socket.create_connection
#urllib3.connection.connection.create_connection=urllib3_create_connection
urllib3.connection.connection.create_connection=default_create_connection

print"***testrequests:"+req.get("http://ip.haschek.at").content
print"***testurllib:"+urllib.urlopen("http://ip.haschek.at").read()
print"***testurllib2:"+urllib2.urlopen("http://ip.haschek.at").read()

注意:使用urllib3.utils.connection好像不起作用

稍微再完善一下,就是把根据网卡名自动获取IP.

importsubprocess

defget_all_net_devices():
sub=subprocess.Popen("ls/sys/class/net",shell=True,stdout=subprocess.PIPE)
sub.wait()
net_devices=sub.stdout.read().strip().splitlines()
#['eth0','eth1','lo']
#这里简单过滤一下网卡名字,根据需求改动
net_devices=[iforiinnet_devicesif"ppp"ini]
returnnet_devices
ALL_DEVICES=get_all_net_devices()

defget_local_ip(device_name):
sub=subprocess.Popen("/sbin/ifconfigen0|grep'%s'|awk'{print$2}'"%device_name,shell=True,stdout=subprocess.PIPE)
sub.wait()
ip=sub.stdout.read().strip()
returnip

defrandom_local_ip():
returnget_local_ip(random.choice(ALL_DEVICES))

#code...

只需要把args[2]=SOURCE_ADDRESS和kwargs["source_address"]=SOURCE_ADDRESS改成random_local_ip()或者get_local_ip("eth0")

至于有什么用途,就全凭想象了.

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Python 使用指定的网卡发送HTTP请求的实例

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