httplib and socket.getaddrinfo

[Gabriel Genellina]

At Saturday 23/12/2006 04:21, mirandacascade at yahoo.com wrote:

>I noticed the following lines from the connect() method of the
>HTTPConnection class within httplib:
>
>         for res in socket.getaddrinfo(self.host, self.port, 0,
>                                       socket.SOCK_STREAM):
>             af, socktype, proto, canonname, sa = res
>
>This led me to the docs that describe the socket.getaddrinfo() method:
>
>http://www.python.org/doc/2.4.1/lib/module-socket.html
>
>Which leads me to these questions:
>1) Is it correct to infer from the "Resolves the host/port argument,
>into a sequence of 5-tuples that contain all the necessary argument for
>the sockets manipulation" description in the docs (in particular the
>reference to 'sequence of 5-tuples') that a single host/port
>combination may be associated with multiple sets of address
>information?

Yes. By example, multiple addresses for the same service are used for 
load balancing. Or an IPv4 address plus an IPv6 address.

>2) In the very limited applications on which I've used
>socket.getaddrinfo(), each a host/port combination that my application
>passes to socket.getaddrinfo() has always returned a 1-entry list where
>the list is a 5-tuple, in other words, each host/port combination has
>always been associated with one set of address information.  Can
>someone point me to a host/port combination that, when passed to
>socket.getaddrinfo() will result in socket.getaddrinfo() returning a
>list of > 1 entry, where each entry is a 5-tuple?

Try to relax your restrictions.

import socket
host = 'www.microsoft.com'
port = 'ftp'
for res in socket.getaddrinfo(host, port):
     print res

Got 8 results:
(2, 1, 0, '', ('207.46.198.30', 21))
(2, 1, 0, '', ('207.46.198.60', 21))
(2, 1, 0, '', ('207.46.199.30', 21))
(2, 1, 0, '', ('207.46.225.60', 21))
(2, 1, 0, '', ('207.46.19.30', 21))
(2, 1, 0, '', ('207.46.19.60', 21))
(2, 1, 0, '', ('207.46.20.30', 21))
(2, 1, 0, '', ('207.46.20.60', 21))


-- 
Gabriel Genellina
Softlab SRL 


	

	
		
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