document pitfall cases in argument parsing. sync with kame.

1 files changed, 64 insertions, 3 deletions

diff --git a/src/lib/libc/net/getaddrinfo.3 b/src/lib/libc/net/getaddrinfo.3
index 9aac4c32c7..bff0344848 100644
--- a/src/lib/libc/net/getaddrinfo.3
+++ b/src/lib/libc/net/getaddrinfo.3
@@ -1,5 +1,5 @@
-.\"     $OpenBSD: getaddrinfo.3,v 1.9 2000/06/30 16:52:44 itojun Exp $
-.\"     $KAME: getaddrinfo.3,v 1.15 2000/06/30 16:46:00 itojun Exp $
+.\"     $OpenBSD: getaddrinfo.3,v 1.10 2000/07/25 04:52:55 itojun Exp $
+.\"     $KAME: getaddrinfo.3,v 1.21 2000/07/25 04:49:42 itojun Exp $
 .\"
 .\" Copyright (c) 1983, 1987, 1991, 1993
 .\"     The Regents of the University of California.  All rights reserved.
@@ -251,6 +251,67 @@ is returned.
 This flag prevents any type of name resolution service (e.g., the DNS)
 from being called.
 .Pp
+The arguments to
+.Fn getaddrinfo
+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 ,
+.Fn 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
 All of the information returned by
 .Fn getaddrinfo
 is dynamically allocated:
@@ -498,7 +559,7 @@ 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