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give pitfall examples. 

in response to couple of PRs including 10666.  sync with kame.
This commit is contained in:
itojun 2000-07-25 02:33:29 +00:00
parent a6d6bce652
commit e3256888e3
1 changed files with 70 additions and 3 deletions
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73
lib/libc/net/getaddrinfo.3
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@ -1,5 +1,5 @@
.\" $NetBSD: getaddrinfo.3,v 1.12 2000/06/30 16:48:47 itojun Exp $
.\" $KAME: getaddrinfo.3,v 1.15 2000/06/30 16:46:00 itojun Exp $
.\" $NetBSD: getaddrinfo.3,v 1.13 2000/07/25 02:33:30 itojun Exp $
.\" $KAME: getaddrinfo.3,v 1.19 2000/07/25 02:27:44 itojun Exp $
.\"
.\" Copyright (c) 1983, 1987, 1991, 1993
.\" The Regents of the University of California. All rights reserved.
@ -169,6 +169,73 @@ structure initialized to zero with
set to
.Dv PF_UNSPEC .
.Pp
Though the
.Fa hints
argument allows you to leave
.Fa ai_socktype
or
.Fa ai_protocol
unspecified
.Pq by setting those members to zero ,
the arguments must sufficiently be consistent and unambiguous.
Here are pitfall cases you may encounter:
.Bl -bullet
.It
.Fn getaddrinfo
will raise error if members in
.Fa hints
structure is not consistent.
For example, for internet address families,
.Fn getaddrinfo
will raise error if you specify
.Dv SOCK_STREAM
to
.Fa ai_socktype
while you specify
.Dv IPPROTO_UDP
to
.Fa ai_protocol .
.It
If you specify a
.Fa servname
which is defined only for certain
.Fa ai_socktype ,
.Fn getaddrinfo
will raise error because the arguments are not consistent.
For example,
.Fn getaddrinfo
will raise error if you ask for
.Dq Li tftp
service on
.Dv SOCK_STREAM .
.It
For internet address families, if you specify
.Fa servname
while you set
.Fa ai_socktype
to
.Dv SOCK_RAW ,
.Fa getaddrinfo
will raise error, because service names are not defined for the internet
.Dv SOCK_RAW
space.
.It
If you specify numeric
.Fa servname ,
while leaving
.Fa ai_socktype
and
.Fa ai_protocol
unspecified,
.Fn getaddrinfo
will raise error.
This is because the numeric
.Fa servname
does not identify any socket type, and
.Fn getaddrinfo
is not allowed to glob the argument in such case.
.El
.Pp
Upon successful return a pointer to a linked list of one or more
.Li addrinfo
structures is returned through the final argument.
@ -518,7 +585,7 @@ indicate an unknown error.
.%A Atsushi Onoe
.%T "An Extension of Format for IPv6 Scoped Addresses"
.%R internet draft
.%N draft-ietf-ipngwg-scopedaddr-format-01.txt
.%N draft-ietf-ipngwg-scopedaddr-format-02.txt
.%O work in progress material
.Re
.Rs