[Python-3000] IPv6 address tuple (original) (raw)

Jun-ichiro itojun Hagino itojun at itojun.org
Tue Apr 3 08:54:57 CEST 2007

| > i understand your concern. current 4-tuple is direct mapping from | > struct sockaddrin6 (which has those two additional members). | | note however, you must rewrite DNS resolving from gethostby* to | get*info anyways, so i'm not too sure if the number of tuple members in | sockaddr matters that much.

This is true when using explicit DNS resolving, but Python socket API allows you to pass in a string in place of the address in the tuple, and then resolves it to an address behind your back. This is probably the most common way of using DNS in Python. It seems that when you have an AFINET6 socket, it looks for an AAAA record, and when you have an AFINET socket, it goes for A.

hmm.  how would Python behave when there are multiple AAAA (or A)
records?  just pick the first one?

Unfortunately this bumps the address family-agnostic get*info API to second place in the convenience-of-use competition (getaddrinfo example at <http://docs.python.org/lib/socket-example.html>).

with mixed IPv4/v6 environment (this would be the network environment
for today and coming decade(s)), a program should try to connect both
A and AAAA records, since connectivity situation varies by
configuration such as network configuration, kernel compilation options
and so forth.
for this reason it would be better (or i might say we have to)
for all libraries (like HTTP, FTP, and stuff) as well as user
applications to use get*info API, instead of just building a tuple and
then use AF_INET/6 socket.

itojun

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