(split) LDP_man-pages: release ioctl.2 [JM:00378]

[linuxjm/LDP_man-pages.git] / draft / man3 / gethostbyname.3

.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
.\"
.\" Permission is granted to make and distribute verbatim copies of this
.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
.\"
.\" Permission is granted to copy and distribute modified versions of this
.\" manual under the conditions for verbatim copying, provided that the
.\" entire resulting derived work is distributed under the terms of a
.\" permission notice identical to this one.
.\"
.\" Since the Linux kernel and libraries are constantly changing, this
.\" manual page may be incorrect or out-of-date.  The author(s) assume no
.\" responsibility for errors or omissions, or for damages resulting from
.\" the use of the information contained herein.  The author(s) may not
.\" have taken the same level of care in the production of this manual,
.\" which is licensed free of charge, as they might when working
.\" professionally.
.\"
.\" Formatted or processed versions of this manual, if unaccompanied by
.\" the source, must acknowledge the copyright and authors of this work.
.\"
.\" References consulted:
.\"     Linux libc source code
.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
.\"     386BSD man pages
.\" Modified 1993-05-22, David Metcalfe
.\" Modified 1993-07-25, Rik Faith (faith@cs.unc.edu)
.\" Modified 1997-02-16, Andries Brouwer (aeb@cwi.nl)
.\" Modified 1998-12-21, Andries Brouwer (aeb@cwi.nl)
.\" Modified 2000-08-12, Andries Brouwer (aeb@cwi.nl)
.\" Modified 2001-05-19, Andries Brouwer (aeb@cwi.nl)
.\" Modified 2002-08-05, Michael Kerrisk
.\" Modified 2004-10-31, Andries Brouwer
.\"
.\" Japanese Version Copyright (c) 1998-2000 NAKANO Takeo all rights reserved.
.\" Translated 1998-04-30, NAKANO Takeo <nakano@apm.seikei.ac.jp>
.\" Modified 1998-12-06, NAKANO Takeo
.\" Updated & Modified 1999-10-12, NAKANO Takeo
.\" Updated & Modified 2001-07-01, Yuichi SATO <ysato@h4.dion.ne.jp>
.\" Updated & Modified 2002-01-03, Yuichi SATO
.\" Updated & Modified 2003-11-27, Yuichi SATO <ysato444@yahoo.co.jp>
.\" Updated & Modified 2005-01-10, Yuichi SATO
.\" Updated 2006-01-18, Akihiro MOTOKI <amotoki@dd.iij4u.or.jp>
.\" Updated 2007-06-11, Akihiro MOTOKI, LDP v2.54
.\" Updated 2008-08-08, Akihiro MOTOKI, LDP v3.05
.\"
.TH GETHOSTBYNAME 3 2010-10-04 "" "Linux Programmer's Manual"
.\"O .SH NAME
.\"O gethostbyname, gethostbyaddr, sethostent, gethostent, endhostent,
.\"O h_errno,
.\"O herror, hstrerror,
.\"O gethostbyaddr_r,
.\"O gethostbyname2, gethostbyname2_r, gethostbyname_r,
.\"O gethostent_r \- get network host entry
.SH ̾Á°
gethostbyname, gethostbyaddr, sethostent, gethostent, endhostent,
h_errno,
herror, hstrerror,
gethostbyaddr_r,
gethostbyname2, gethostbyname2_r, gethostbyname_r,
gethostent_r \- ¥Í¥Ã¥È¥ï¡¼¥¯¾å¤Î¥Û¥¹¥È¤Î¥¨¥ó¥È¥ê¤ò¼èÆÀ¤¹¤ë
.\"O .SH SYNOPSIS
.SH ½ñ¼°
.nf
.B #include <netdb.h>
.B extern int h_errno;
.sp
.BI "struct hostent *gethostbyname(const char *" name );
.sp
.\"O .BR "#include <sys/socket.h>" "       /* for AF_INET */"
.BR "#include <sys/socket.h>" "       /* AF_INET ¤ò»È¤¦¾ì¹ç */"
.BI "struct hostent *gethostbyaddr(const void *" addr ,
.BI "                              socklen_t " len ", int " type );
.sp
.BI "void sethostent(int " stayopen );
.sp
.B void endhostent(void);
.sp
.BI "void herror(const char *" s );
.sp
.BI "const char *hstrerror(int " err );
.sp
.\"O /* System V/POSIX extension */
/* System V/POSIX ³ÈÄ¥ */
.br
.B struct hostent *gethostent(void);
.sp
.\"O /* GNU extensions */
/* GNU ³ÈÄ¥ */
.br
.BI "struct hostent *gethostbyname2(const char *" name ", int " af );
.sp
.B "int gethostent_r("
.BI "        struct hostent *" ret ", char *" buf ", size_t " buflen ,
.BI "        struct hostent **" result ", int *" h_errnop );
.sp
.BI "int gethostbyaddr_r(const void *" addr ", socklen_t " len ", int " type ,
.BI "        struct hostent *" ret ", char *" buf ", size_t " buflen ,
.BI "        struct hostent **" result ", int *" h_errnop );
.sp
.BI "int gethostbyname_r(const char *" name ,
.BI "        struct hostent *" ret ", char *" buf ", size_t " buflen ,
.BI "        struct hostent **" result ", int *" h_errnop );
.sp
.BI "int gethostbyname2_r(const char *" name ", int " af,
.BI "        struct hostent *" ret ", char *" buf ", size_t " buflen ,
.BI "        struct hostent **" result ", int *" h_errnop );
.fi
.sp
.in -4n
.\"O Feature Test Macro Requirements for glibc (see
.\"O .BR feature_test_macros (7)):
glibc ¸þ¤±¤Îµ¡Ç½¸¡ºº¥Þ¥¯¥í¤ÎÍ×·ï
.RB ( feature_test_macros (7)
»²¾È):
.in
.sp
.PD 0
.ad l
.BR gethostbyname2 (),
.BR gethostent_r (),
.BR gethostbyaddr_r (),
.BR gethostbyname_r (),
.BR gethostbyname2_r ():
.RS 4
_BSD_SOURCE || _SVID_SOURCE
.RE

.BR herror (),
.BR hstrerror ():
.RS 4
.TP 4
.\"O Since glibc 2.8:
glibc 2.8 °Ê¹ß:
_BSD_SOURCE || _SVID_SOURCE || _GNU_SOURCE
.TP
.\"O Before glibc 2.8:
.\"O none
glibc 2.8 ¤è¤êÁ°:
¤Ê¤·
.RE
.ad b
.PD
.\"O .SH DESCRIPTION
.SH ÀâÌÀ
.\"O The
.\"O .BR gethostbyname* ()
.\"O and
.\"O .BR gethostbyaddr* ()
.\"O functions are obsolete.
.\"O Applications should use
.\"O .BR getaddrinfo (3)
.\"O and
.\"O .BR getnameinfo (3)
.\"O instead.
.BR gethostbyname* ()
¤È
.BR gethostbyaddr* ()
¤Ï²áµî¤Î¤â¤Î¤Ç¤¢¤ë¡£
¥¢¥×¥ê¥±¡¼¥·¥ç¥ó¤Ç¤Ï¡¢Âå¤ï¤ê¤Ë
.BR getaddrinfo (3)
¤È
.BR getnameinfo (3)
¤ò»ÈÍѤ¹¤ë¤³¤È¡£

.\"O The
.\"O .BR gethostbyname ()
.\"O function returns a structure of type
.\"O .I hostent
.\"O for the given host
.\"O .IR name .
.\"O Here
.\"O .I name
.\"O is either a hostname, or an IPv4 address in standard dot notation (as for
.\"O .BR inet_addr (3)),
.\"O or an IPv6 address in colon (and possibly dot) notation.
.\"O (See RFC\ 1884 for the description of IPv6 addresses.)
.BR gethostbyname ()
´Ø¿ô¤ÏÍ¿¤¨¤é¤ì¤¿¥Û¥¹¥È̾
.I name
¤ËÂбþ¤¹¤ë¹½Â¤ÂÎ
.I hostent
¤òÊÖ¤¹¡£
.I name
¤Ë¤Ï¥Û¥¹¥È̾¡¢¥É¥Ã¥È¶èÀÚ¤ê¤Î IPv4 ¥¢¥É¥ì¥¹
.RB ( inet_addr (3)
»²¾È)¡¢¥³¥í¥ó¶èÀÚ¤ê¤Î IPv6 ¥¢¥É¥ì¥¹ (¤ª¤½¤é¤¯¥É¥Ã¥È¶èÀÚ¤ê¤Ç¤âÂç¾æÉ×)
¤Î¤¤¤º¤ì¤«¤ò»ØÄꤹ¤ë
(IPv6 ¥¢¥É¥ì¥¹¤Îµ­½ÒÊýË¡¤Ë¤Ä¤¤¤Æ¤Ï RFC\ 1884 ¤ò»²¹Í¤Ë¤·¤Æ¤Û¤·¤¤)¡£
.\"O If
.\"O .I name
.\"O is an IPv4 or IPv6 address, no lookup is performed and
.\"O .BR gethostbyname ()
.\"O simply copies
.\"O .I name
.\"O into the
.\"O .I h_name
.\"O field and its
.\"O .I struct in_addr
.\"O equivalent into the
.\"O .I h_addr_list[0]
.\"O field of the returned
.\"O .I hostent
.\"O structure.
.I name
¤¬ IPv4 ¤« IPv6 ¤Î¥¢¥É¥ì¥¹¤À¤Ã¤¿¾ì¹ç¡¢
̾Á°²ò·è (lookup) ¤Ï¹Ô¤ï¤ì¤Ê¤¤¡£¤½¤Î¾ì¹ç¤Ë¤Ï¡¢
.BR gethostbyname ()
¤Ï
.I name
¤ò¤½¤Î¤Þ¤Þ
.I hostent
¹½Â¤ÂΤÎ
.I h_name
¥Õ¥£¡¼¥ë¥É¤Ë¥³¥Ô¡¼¤·¡¢
¤µ¤é¤Ë
.I name
¤ò
.I struct in_addr
·Á¼°¤Çɽ¤·¤¿¥Ç¡¼¥¿¤ò
.I hostent
¹½Â¤ÂΤÎ
.I h_addr_list[0]
¥Õ¥£¡¼¥ë¥É¤ËÆþ¤ì¤Æ¡¢¤½¤Î
.I hostent
¹½Â¤ÂΤòÊÖ¤¹¡£
.\"O If
.\"O .I name
.\"O doesn't end in a dot and the environment variable
.\"O .B HOSTALIASES
.\"O is set, the alias file pointed to by
.\"O .B HOSTALIASES
.\"O will first be searched for
.\"O .I name
.\"O (see
.\"O .BR hostname (7)
.\"O for the file format).
.I name
¤¬¥É¥Ã¥È¤Ç½ªÎ»¤·¤Æ¤¤¤Æ¡¢¤«¤Ä´Ä¶­ÊÑ¿ô
.B HOSTALIASES
¤¬ÀßÄꤵ¤ì¤Æ¤¤¤ë¾ì¹ç¡¢¤Þ¤º
.B HOSTALIASES
¤Ç»ØÄꤵ¤ì¤Æ¤¤¤ë¥¨¥¤¥ê¥¢¥¹¥Õ¥¡¥¤¥ë¤«¤é
.I name
¤Î¥¨¥ó¥È¥ê¤¬¸¡º÷¤µ¤ì¤ë (¥Õ¥¡¥¤¥ë¤Î¥Õ¥©¡¼¥Þ¥Ã¥È¤Ë¤Ä¤¤¤Æ¤Ï
.BR hostname (7)
¤ò»²¾È¤Î¤³¤È)¡£
.\"O The current domain and its parents are searched unless \fIname\fP
.\"O ends in a dot.
.I name
¤¬¥É¥Ã¥È¤Ç½ªÎ»¤·¤Æ¤¤¤Ê¤±¤ì¤Ð¡¢¸½ºß¤Î¥É¥á¥¤¥ó¤È¤½¤Î¿Æ¥É¥á¥¤¥ó¤¬¸¡º÷¤µ¤ì¤ë¡£
.PP
.\"O The
.\"O .BR gethostbyaddr ()
.\"O function returns a structure of type \fIhostent\fP
.\"O for the given host address \fIaddr\fP of length \fIlen\fP and address type
.\"O \fItype\fP.
.\"O Valid address types are
.\"O .B AF_INET
.\"O and
.\"O .BR AF_INET6 .
.BR gethostbyaddr ()
´Ø¿ô¤ÏÍ¿¤¨¤é¤ì¤¿¥Û¥¹¥È¥¢¥É¥ì¥¹
.I addr
(Ťµ \fIlen\fP¡¢ ¥¿¥¤¥× \fItype\fP) ¤ËÂбþ¤¹¤ë¹½Â¤ÂÎ
.I hostent
¤òÊÖ¤¹¡£
ÍѤ¤¤ë¤³¤È¤Î¤Ç¤­¤ë¥¿¥¤¥×¤Ï
.B AF_INET
¤È
.B AF_INET6
¤Ç¤¢¤ë¡£
.\"O The host address argument is a pointer to a struct of a type depending
.\"O on the address type, for example a \fIstruct in_addr *\fP (probably
.\"O obtained via a call to
.\"O .BR inet_addr (3))
.\"O for address type
.\"O .BR AF_INET .
¥Û¥¹¥È¥¢¥É¥ì¥¹°ú¤­¿ô¤Ï¥¢¥É¥ì¥¹¥¿¥¤¥×¤Ë°Í¸¤·¤¿
¹½Â¤ÂΤؤΥݥ¤¥ó¥¿¤Ç¤¢¤ë¡£
Î㤨¤Ð¡¢¥¢¥É¥ì¥¹¥¿¥¤¥×
.B AF_INET
¤ËÂФ·¤Æ¤Ï
.RB ( inet_addr (3)
¤Î¸Æ¤Ó½Ð¤·¤ÇÆÀ¤é¤ì¤ë)
\fIstruct in_addr *\fP ¤Ç¤¢¤ë¡£
.PP
.\"O The
.\"O .BR sethostent ()
.\"O function specifies, if \fIstayopen\fP is true (1),
.\"O that a connected TCP socket should be used for the name server queries and
.\"O that the connection should remain open during successive queries.
.\"O Otherwise, name server queries will use UDP datagrams.
.BR sethostent ()
´Ø¿ô¤Ï¡¢¥Í¡¼¥à¥µ¡¼¥Ð¤Ø¤ÎÀܳ·ÁÂÖ¤ò»ØÄꤹ¤ë¡£
.I stayopen
¤¬¿¿ (1) ¤Ê¤é¤Ð¡¢¥Í¡¼¥à¥µ¡¼¥Ð¤Ø¤ÎÌ䤤¹ç¤ï¤»¤Ë¤Ï¡¢
Àܳ¤µ¤ì¤¿ TCP ¥½¥±¥Ã¥È¤òÍѤ¤¡¢Ï¢Â³¤·¤¿Ì䤤¹ç¤ï¤»¤Î´Ö¤ËÀܳ¤ò°Ý»ý¤¹¤ë¡£
µ¶¤Ê¤é¤Ð¥Í¡¼¥à¥µ¡¼¥Ð¤Ø¤ÎÌ䤤¹ç¤ï¤»¤Ë UDP ¥Ç¡¼¥¿¥°¥é¥à¤òÍѤ¤¤ë¡£
.PP
.\"O The
.\"O .BR endhostent ()
.\"O function ends the use of a TCP connection for name
.\"O server queries.
.BR endhostent ()
´Ø¿ô¤Ï¥Í¡¼¥à¥µ¡¼¥Ð¤Ø¤ÎÌ䤤¹ç¤ï¤»¤ËÍѤ¤¤¿ TCP Àܳ¤ÎÍøÍѤò½ªÎ»¤¹¤ë¡£
.PP
.\"O The (obsolete)
.\"O .BR herror ()
.\"O function prints the error message associated
.\"O with the current value of \fIh_errno\fP on \fIstderr\fP.
(ÇÑ»ßͽÄê¤Î)
.BR herror ()
´Ø¿ô¤Ï¸½ºß¤Î
.I h_errno
¤ËÂбþ¤¹¤ë¥¨¥é¡¼¥á¥Ã¥»¡¼¥¸¤òɸ½à¥¨¥é¡¼ \fIstderr\fP ¤Ë½ÐÎϤ¹¤ë¡£
.PP
.\"O The (obsolete)
.\"O .BR hstrerror ()
.\"O function takes an error number
.\"O (typically \fIh_errno\fP) and returns the corresponding message string.
(ÇÑ»ßͽÄê¤Î)
.BR hstrerror ()
´Ø¿ô¤Ï¥¨¥é¡¼ÈÖ¹æ (Ä̾ï¤Ï \fIh_errno\fP) ¤ò°ú¤­¿ô¤Ë¼è¤ê¡¢
Âбþ¤¹¤ë¥¨¥é¡¼¥á¥Ã¥»¡¼¥¸Ê¸»úÎó¤òÊÖ¤¹¡£
.PP
.\"O The domain name queries carried out by
.\"O .BR gethostbyname ()
.\"O and
.\"O .BR gethostbyaddr ()
.\"O use a combination of any or all of the name server
.\"O .BR named (8),
.\"O a broken out line from \fI/etc/hosts\fP, and the Network
.\"O Information Service (NIS or YP), depending upon the contents of the
.\"O \fIorder\fP line in
.\"O .IR /etc/host.conf .
.\"O .\" (See
.\"O .\" .BR resolv+ (8)).
.\"O The default action is to query
.\"O .BR named (8),
.\"O followed by
.\"O .IR /etc/hosts .
.BR gethostbyname ()
¤È
.BR gethostbyaddr ()
¤Ë¤è¤Ã¤Æ¼Â¹Ô¤µ¤ì¤ë¥É¥á¥¤¥ó̾¤ÎÌ䤤¹ç¤ï¤»¤Ç¤Ï¡¢¥Í¡¼¥à¥µ¡¼¥Ð
.BR named (8)¡¢
.I /etc/hosts
¤Î¥Ç¡¼¥¿¹Ô¡¢¤ª¤è¤Ó
Network Information Service (NIS ¤Þ¤¿¤Ï YP)
¤¬ÁȤ߹ç¤ï¤»¤Æ»ÈÍѤµ¤ì¤ë¡£²¿¤¬»ÈÍѤµ¤ì¤ë¤«¤Ï¡¢
.I /etc/host.conf
¤Î
.I order
¹Ô¤ÎÆâÍƤˤè¤ê·è¤Þ¤ë¡£
.\" (¾Ü¤·¤¯¤Ï
.\" .BR resolv+ (8)
.\" ¤ò»²¾È)¡£
¥Ç¥Õ¥©¥ë¥È¤Ç¤Ï¡¢¤Þ¤º
.BR named (8)
¤ËÌ䤤¹ç¤ï¤»¤ò¹Ô¤¤¡¢¼¡¤¤¤Ç
.I /etc/hosts
¤ò»²¾È¤¹¤ë¡£
.PP
.\"O The \fIhostent\fP structure is defined in \fI<netdb.h>\fP as follows:
.I hostent
¹½Â¤ÂΤÏ
.I <netdb.h>
¤Ç°Ê²¼¤Î¤è¤¦¤ËÄêµÁ¤µ¤ì¤Æ¤¤¤ë:
.sp
.in +4n
.nf
.ne 7
struct hostent {
    char  *h_name;            /* official name of host */
    char **h_aliases;         /* alias list */
    int    h_addrtype;        /* host address type */
    int    h_length;          /* length of address */
    char **h_addr_list;       /* list of addresses */
}
.\"O #define h_addr h_addr_list[0] /* for backward compatibility */
#define h_addr h_addr_list[0] /* ²áµî¤È¤Î¸ß´¹À­¤Î¤¿¤á */
.fi
.in
.PP
.\"O The members of the \fIhostent\fP structure are:
.I hostent
¹½Â¤ÂΤΥá¥ó¥Ð¤Ï°Ê²¼¤ÎÄ̤ꡣ
.TP
.I h_name
.\"O The official name of the host.
¥Û¥¹¥È¤ÎÀµ¼°Ì¾ (official name)¡£
.TP
.I h_aliases
.\"O An array of alternative names for the host, terminated by a NULL pointer.
¥Û¥¹¥È¤ÎÊÌ̾¤ÎÇÛÎó¡£ÇÛÎó¤Ï NULL ¥Ý¥¤¥ó¥¿¤Ç½ªÃ¼¤µ¤ì¤ë¡£
.TP
.I h_addrtype
.\"O The type of address; always
.\"O .B AF_INET
.\"O or
.\"O .B AF_INET6
.\"O at present.
¥¢¥É¥ì¥¹¤Î¥¿¥¤¥×¡£¸½ºß¤Ï¤¹¤Ù¤Æ
.B AF_INET
¤Þ¤¿¤Ï
.B AF_INET6
¤Ç¤¢¤ë¡£
.TP
.I h_length
.\"O The length of the address in bytes.
¥Ð¥¤¥Èñ°Ì¤Çɽ¤·¤¿¥¢¥É¥ì¥¹¤ÎŤµ¡£
.TP
.I h_addr_list
.\"O An array of pointers to network addresses for the host (in network byte
.\"O order), terminated by a NULL pointer.
¥Û¥¹¥È¤Î¥Í¥Ã¥È¥ï¡¼¥¯¥¢¥É¥ì¥¹¤Ø¤Î¥Ý¥¤¥ó¥¿¤ÎÇÛÎó¡£
ÇÛÎó¤Ï NULL ¥Ý¥¤¥ó¥¿¤Ç½ªÃ¼¤µ¤ì¤ë¡£
¥Í¥Ã¥È¥ï¡¼¥¯¥¢¥É¥ì¥¹¤Ï¥Í¥Ã¥È¥ï¡¼¥¯¥Ð¥¤¥È¥ª¡¼¥À·Á¼°¤Ç¤¢¤ë¡£
.TP
.I h_addr
.\"O The first address in \fIh_addr_list\fP for backward compatibility.
.I h_addr_list
¤ÎºÇ½é¤Î¥¢¥É¥ì¥¹¡£²áµî¤È¤Î¸ß´¹À­¤òÊݤĤ¿¤á¤Î¤â¤Î¤Ç¤¢¤ë¡£
.\"O .SH "RETURN VALUE"
.SH ÊÖ¤êÃÍ
.\"O The
.\"O .BR gethostbyname ()
.\"O and
.\"O .BR gethostbyaddr ()
.\"O functions return the
.\"O .I hostent
.\"O structure or a NULL pointer if an error occurs.
.\"O On error, the
.\"O .I h_errno
.\"O variable holds an error number.
.BR gethostbyname ()
¤ª¤è¤Ó
.BR gethostbyaddr ()
´Ø¿ô¤Ï
.I hostent
¹½Â¤ÂΤòÊÖ¤¹¡£¥¨¥é¡¼¤¬µ¯¤³¤Ã¤¿¤é NULL ¥Ý¥¤¥ó¥¿¤òÊÖ¤¹¡£¥¨¥é¡¼¤ÎºÝ¤Ë¤Ï
.I h_errno
ÊÑ¿ô¤¬¥¨¥é¡¼¤ÎÈÖ¹æ¤òÊÝ»ý¤¹¤ë¡£
.\"O When non-NULL, the return value may point at static data, see the notes below.
ÊÖ¤êÃͤ¬ NULL ¤Ç¤Ê¤¤¾ì¹ç¡¢ÀÅŪ¥Ç¡¼¥¿¤ò¥Ý¥¤¥ó¥¿¤Ç»Ø¤·¤Æ¤¤¤ë¤³¤È¤â¤¢¤ë¡£
°Ê²¼¤Î¡ÖÃí°Õ¡×¤ò»²¾È¤¹¤ë¤³¤È¡£
.\"O .SH "ERRORS"
.SH ¥¨¥é¡¼
.\"O The variable \fIh_errno\fP can have the following values:
.I h_errno
ÊÑ¿ô¤Ï°Ê²¼¤ÎÃͤò¼è¤ê¤¦¤ë¡£
.TP
.B HOST_NOT_FOUND
.\"O The specified host is unknown.
»ØÄꤷ¤¿¥Û¥¹¥È¤¬¸«¤Ä¤«¤é¤Ê¤¤¡£
.TP
.\"O .B NO_ADDRESS " or " NO_DATA
.B NO_ADDRESS " ¤Þ¤¿¤Ï " NO_DATA
.\"O The requested name is valid but does not have an IP address.
»ØÄꤷ¤¿Ì¾Á°¤ÏÍ­¸ú¤À¤¬ IP ¥¢¥É¥ì¥¹¤ò»ý¤Ã¤Æ¤¤¤Ê¤¤¡£
.TP
.B NO_RECOVERY
.\"O A nonrecoverable name server error occurred.
¥Í¡¼¥à¥µ¡¼¥Ð¤ÎÉüµìÉÔǽ¤Ê¥¨¥é¡¼¤¬µ¯¤³¤Ã¤¿¡£
.TP
.B TRY_AGAIN
.\"O A temporary error occurred on an authoritative name server.
.\"O Try again later.
authoritative ¤Ê¥Í¡¼¥à¥µ¡¼¥Ð¤Ç°ì»þŪ¤Ê¥¨¥é¡¼¤¬µ¯¤³¤Ã¤¿¡£
»þ´Ö¤ò¤ª¤¤¤Æ¤â¤¦°ìÅٻ¤³¤È¡£
.\"O .SH FILES
.SH ¥Õ¥¡¥¤¥ë
.TP
.I /etc/host.conf
.\"O resolver configuration file
̾Á°²ò·è¤ÎÀßÄê¥Õ¥¡¥¤¥ë
.TP
.I /etc/hosts
.\"O host database file
¥Û¥¹¥È¤Î¥Ç¡¼¥¿¥Ù¡¼¥¹¥Õ¥¡¥¤¥ë
.TP
.I /etc/nsswitch.conf
.\"O name service switch configuration
¥Í¡¼¥à¥µ¡¼¥Ó¥¹ÀÚÂØÀßÄê
.\"O .SH "CONFORMING TO"
.SH ½àµò
.\"O POSIX.1-2001 specifies
.\"O .BR gethostbyname (),
.\"O .BR gethostbyaddr (),
.\"O .BR sethostent (),
.\"O .BR endhostent (),
.\"O .BR gethostent (),
.\"O and
.\"O .IR h_errno ;
.\"O .BR gethostbyname (),
.\"O .BR gethostbyaddr (),
.\"O and
.\"O .IR h_errno
.\"O are marked obsolescent in that standard.
POSIX.1-2001 ¤Ç¤Ï¡¢
.BR gethostbyname (),
.BR gethostbyaddr (),
.BR sethostent (),
.BR endhostent (),
.BR gethostent (),
.I h_errno
¤¬µ¬Äꤵ¤ì¤Æ¤ª¤ê¡¢
.BR gethostbyaddr ()
¤È
.BR gethostbyname ()
¤ÏÇÑ»ßͽÄê¤Ç¤¢¤ë¤È¤µ¤ì¤Æ¤¤¤ë¡£
.\"O POSIX.1-2008 removes the specifications of
.\"O .BR gethostbyname (),
.\"O .BR gethostbyaddr (),
.\"O and
.\"O .IR h_errno ,
.\"O recommending the use of
.\"O .BR getaddrinfo (3)
.\"O and
.\"O .BR getnameinfo (3)
.\"O instead.
POSIX.1-2008 ¤Ç¤Ï
.BR gethostbyname (),
.BR gethostbyaddr (),
.I h_errno
¤Î»ÅÍͤ¬ºï½ü¤µ¤ì¤Æ¤¤¤ë¡£
Âå¤ï¤ê¤Ë¡¢
.BR getaddrinfo (3)
¤È
.BR getnameinfo (3)
¤Î»ÈÍѤ¬¿ä¾©¤µ¤ì¤Æ¤¤¤ë¡£
.\"O .SH NOTES
.SH Ãí°Õ
.\"O The functions
.\"O .BR gethostbyname ()
.\"O and
.\"O .BR gethostbyaddr ()
.\"O may return pointers to static data, which may be overwritten by
.\"O later calls.
.\"O Copying the
.\"O .I struct hostent
.\"O does not suffice, since it contains pointers; a deep copy is required.
.BR gethostbyname ()
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.BR gethostbyaddr ()
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.I hostent
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.LP
.\"O In the original BSD implementation the
.\"O .I len
.\"O argument
.\"O of
.\"O .BR gethostbyname ()
.\"O was an
.\"O .IR int .
¥ª¥ê¥¸¥Ê¥ë¤Î BSD ¤Î¼ÂÁõ¤Ç¤Ï¡¢
.BR gethostbyname ()
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.I len
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.\"O The SUSv2 standard is buggy and declares the
.\"O .I len
.\"O argument of
.\"O .BR gethostbyaddr ()
.\"O to be of type
.\"O .IR size_t .
.\"O (That is wrong, because it has to be
.\"O .IR int ,
.\"O and
.\"O .I size_t
.\"O is not.
.\"O POSIX.1-2001 makes it
.\"O .IR socklen_t ,
.\"O which is OK.)
.\"O See also
.\"O .BR accept (2).
SUSv2 ɸ½à¤Ï¥Ð¥°¤¬Â¿¤¯¡¢
.BR gethostbyaddr ()
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.I len
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.I size_t
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POSIX.1-2001 ¤Ç¤Ï¤³¤ì¤ò
.I socklen_t
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.BR accept (2)
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.LP
.\"O The BSD prototype for
.\"O .BR gethostbyaddr ()
.\"O uses
.\"O .I const char *
.\"O for the first argument.
.BR gethostbyaddr ()
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.I const char *
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.\"O .SS "System V/POSIX Extension"
.SS "System V/POSIX ³ÈÄ¥"
.\"O POSIX requires the
.\"O .BR gethostent ()
.\"O call, that should return the next entry in the host data base.
POSIX ¤Ç¤Ï¡¢
.BR gethostent ()
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.\"O When using DNS/BIND this does not make much sense, but it may
.\"O be reasonable if the host data base is a file that can be read
.\"O line by line.
.\"O On many systems a routine of this name reads
.\"O from the file
.\"O .IR /etc/hosts .
DNS/BIND ¤ò»È¤¦¾ì¹ç¤Ï¤¢¤Þ¤ê°ÕÌ£¤ò»ý¤¿¤Ê¤¤¤¬¡¢
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.I /etc/hosts
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.\"O .\" e.g., Linux, FreeBSD, UnixWare, HP-UX
.\"O It may be available only when the library was built without DNS support.
.\"O .\" e.g., FreeBSD, AIX
.\"O The glibc version will ignore ipv6 entries.
.\"O This function is not reentrant,
.\"O and glibc adds a reentrant version
.\"O .BR gethostent_r ().
.\" Î㤨¤Ð¡¢Linux, FreeBSD, UnixWare, HP-UX
DNS ¥µ¥Ý¡¼¥È¤Ê¤·¤Ç¥é¥¤¥Ö¥é¥ê¤¬¥Ó¥ë¥É¤µ¤ì¤¿¾ì¹ç¤Ë¤Î¤ßÍøÍѲÄǽ¤Ç¤¢¤ë¡£
.\" Î㤨¤Ð¡¢FreeBSD, AIX
glibc ÈÇ¤Ï ipv6 ¥¨¥ó¥È¥ê¤ò̵»ë¤¹¤ë¡£
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glibc ¤Ë¤Ï¥ê¥¨¥ó¥È¥é¥ó¥ÈÈǤÎ
.BR gethostent_r ()
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.\"O .SS "GNU Extensions"
.SS "GNU ³ÈÄ¥"
.\"O Glibc2 also has a
.\"O .BR gethostbyname2 ()
.\"O that works like
.\"O .BR gethostbyname (),
.\"O but permits to specify the address family to which the address must belong.
glibc2 ¤Ë¤Ï
.BR gethostbyname2 ()
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.LP
.\"O Glibc2 also has reentrant versions
.\"O .BR gethostent_r (),
.\"O .BR gethostbyaddr_r (),
.\"O .BR gethostbyname_r ()
.\"O and
.\"O .BR gethostbyname2_r ().
glibc2 ¤Ë¤Ï¥ê¥¨¥ó¥È¥é¥ó¥È¤Ê
.BR gethostent_r (),
.BR gethostbyaddr_r (),
.BR gethostbyname_r ()
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.BR gethostbyname2_r ()
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.\"O The caller supplies a
.\"O .I hostent
.\"O structure
.\"O .I ret
.\"O which will be filled in on success, and a temporary work buffer
.\"O .I buf
.\"O of size
.\"O .IR buflen .
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.I hostent
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.I buf
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.\"O After the call,
.\"O .I result
.\"O will point to the result on success.
.\"O In case of an error
.\"O or if no entry is found
.\"O .I result
.\"O will be NULL.
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.I result
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.I result
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.\"O The functions return 0 on success and a nonzero error number on failure.
.\"O In addition to the errors returned by the nonreentrant
.\"O versions of these functions, if
.\"O .I buf
.\"O is too small, the functions will return
.\"O .BR ERANGE ,
.\"O and the call should be retried with a larger buffer.
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.\"O The global variable
.\"O .I h_errno
.\"O is not modified, but the address of a variable in which to store error numbers
.\"O is passed in
.\"O .IR h_errnop .
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.I h_errno
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.I h_errnop
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.\"O .SH BUGS
.SH ¥Ð¥°
.\"O .BR gethostbyname ()
.\"O does not recognize components of a dotted IPv4 address string
.\"O that are expressed in hexadecimal.
.BR gethostbyname ()
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.\" http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=482973
.\"O .SH "SEE ALSO"
.SH ´ØÏ¢¹àÌÜ
.BR getaddrinfo (3),
.\" .BR getipnodebyaddr (3),
.\" .BR getipnodebyname (3),
.BR getnameinfo (3),
.BR inet (3),
.BR inet_ntop (3),
.BR inet_pton (3),
.BR resolver (3),
.BR hosts (5),
.BR nsswitch.conf (5),
.BR hostname (7),
.BR named (8)
.\" .BR resolv+ (8)