.\" Copyright (c) 1983, 1990, 1991 The Regents of the University of California.
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"	This product includes software developed by the University of
.\"	California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\"     $Id: recv.2,v 1.8 2001/08/15 18:00:48 hanataka Exp $
.\"
.\" Modified Sat Jul 24 00:22:20 1993 by Rik Faith <faith@cs.unc.edu>
.\" Modified Tue Oct 22 17:45:19 1996 by Eric S. Raymond <esr@thyrsus.com>
.\" Modified 1998,1999 by Andi Kleen
.\" 2001-06-19 corrected SO_EE_OFFENDER, bug report by James Hawtin
.\"
.\" Japanese Version Copyright (c) 1996 Akira Yoshiyama
.\"         all rights reserved.
.\" Translated Thu Jul 18 01:24:02 JST 1996
.\"         by Akira Yoshiyama <yosshy@jedi.seg.kobe-u.ac.jp>
.\" Modified Sun Dec 14 22:37:11 JST 1997
.\"         by HANATAKA Shinya <hanataka@abyss.rim.or.jp>
.\" Modified Sat Aug 14 10:48:41 JST 1999
.\"         by HANATAKA Shinya <hanataka@abyss.rim.or.jp>
.\" Updated & Modified Thu Oct 12 2000
.\"         by HAYAKAWA Hitoshi <cz8cb01@linux.or.jp>
.\"        and NAKANO Takeo <nakano@apm.seikei.ac.jp>
.\" Updated & Modified Fri Feb 9 2001 by NAKANO Takeo
.\" Updated Sat Oct 11 JST 2003 by Kentaro Shirakata <argrath@ub32.org>
.\"
.\"WORD:	ancillary data		ǡ
.\"WORD:	ancillary message	å
.\"WORD:	invalid			
.\"
.TH RECV 2 2002-12-31 "Linux Man Page" "Linux Programmer's Manual"
.SH ̾
recv, recvfrom, recvmsg \- åȤå
.SH 
.\" .B #include <sys/uio.h>
.\" .br
.B #include <sys/types.h>
.br
.B #include <sys/socket.h>
.sp
.BI "ssize_t recv(int " s ", void *" buf ", size_t " len ", int " flags );
.sp
.BI "ssize_t recvfrom(int " s ", void *" buf ", size_t " len ,
.BI "int " flags ", struct sockaddr *" from ", socklen_t *" fromlen );
.sp
.BI "ssize_t recvmsg(int " s ", struct msghdr *" msg ", int " flags );
.SH 
.B recvfrom

.B recvmsg
ϥåȤå뤿Ѥ롣
ޤåȤΥǡˤѤ뤳Ȥǽǡ
ΤȤåȤ³ظ (connection-oriened) ǤäƤʤƤ褤
.PP
.I from
 NULL ʳǡåȤ³ظǤʤ硢
.I from
ˤϥåɥ쥹롣

.I fromlen
ξѤΥѥ᡼ǡǽ
.IR from 
˳ƤХåե礭Ƥ֤äƤˤ
.I from 
˼ºݤ줿ɥ쥹礭˽֤롣
.PP
.B recv
̾
.I ³Ѥߤ (connected)
å
.RB ( connect (2)
򻲾) ˤĤƤΤ߻Ѥ졢
.I from
ѥ᡼ NULL 
.B recvfrom
Ǥ롣
.PP
λĤΥ롼Ϥ٤ơˤϥåĹ֤
åĹ᤮Ϳ줿ХåեǼޤʤäˤϡ
ååȤμˤäƤ;ʬΥХȤΤƤ
⤷ʤ
.RB ( socket (2)
򻲾)
.PP
åȤ˼å¸ߤʤä硢
ѤΥϥå夹ޤԤġ
åȤ (nonblocking)
ꤵƤ
.RB ( fcntl (2)
򻲾)  \-1 ֤ѿ
.I errno

.B EAGAIN
ꤵ롣
μϡ׵ᤷãʤƤ
ǡ򥨥顼ʤ֤
׵ᤷäѤޤԤĤȤϤʤ
.PP
.BR select (2)

.BR poll (2)
ȤäơΥǡϤȽǤǤ롣
.PP
recv 
.I flags
ϼͤΰİʾ
.I OR ()
äƻꤹ:
.TP
.B MSG_OOB
Υե饰̾Υǡȥ꡼ǼǤʤ
Ӱ賰 (out-of-band) ǡμ׵᤹롣
ץȥˤäƤϡ
̾Υǡ塼Ƭ®ãǡ֤Τ뤬
Τ褦ʥץȥǤϤΥե饰ϻѤǤʤ
.TP
.B MSG_PEEK
Υե饰ꤹȡ
塼κǽΥǡ֤Ȥ塼ǡʤ
äơʹߤμǤƱǡ֤뤳Ȥˤʤ롣
.TP
.B MSG_WAITALL
Υե饰ϡ׵ᤷ̤äѤΥǡ夹ޤǡ
 (block) 褦׵᤹롣
ʤ顢ʥꡢ顼 (disconnect) ȯꡢ
˼ǡۤʤ뷿äꤷˤϡ
׵ᤷ̤꾯ʤǡ֤Ȥ롣
.TP
.B MSG_NOSIGNAL 
Υե饰ϥȥ꡼ॽåȤ¦äȯ
.B SIGPIPE
ʥȯʤ褦ˤ롣
.TP
.B MSG_TRUNC
ѥåȤμºݤĹϤХåեĹäˤ⡢
Ĺ֤packet åȤФƤΤͭ
.TP
.B MSG_ERRQUEUE
Υե饰ꤹȡ
塼줿顼åȤΥ顼塼褦ˤʤ롣
Υ顼åȤ߹ޤϤ졢
åηϥץȥ˰¸Ƥ
(IPv4 ξ
.BR IP_RECVERR )
桼ϽʬʥΥХåեѰդʤФʤʤ
å˴ؤܺ٤ʾ
.BR cmsg (3)

.BR ip (7)
򻲾ȤΤȡ
顼򵯤ꥸʥѥåȤΥڥɤϡ
.B msg_iovec
ˤä̾ΥǡȤϤ롣
顼򵯤ǡΥꥸʥιԤ襢ɥ쥹ϡ
.B msg_name
ˤäͿ롣
.IP
ʥ顼ξϥɥ쥹Ϥʤ
(
.B cmsghdr

.I cmsg_len
СˤäƥåǤ)
顼ξ
.B MSG_ERRQUIE

.B msghdr
˥åȤ롣
顼Ϥ줿ˤϡ
ڥǥ󥰤Ƥåȡ顼
Υ塼줿顼˴Ťƺƺ졢
ΥåκݤϤ롣
.IP
Υ顼
.B sock_extended_err
¤Τ󶡤:
.IP
.RS
.ne 18
.nf
.ta 4n 20n 32n
#define SO_EE_ORIGIN_NONE	0
#define SO_EE_ORIGIN_LOCAL	1
#define SO_EE_ORIGIN_ICMP	2
#define SO_EE_ORIGIN_ICMP6	3

struct sock_extended_err
{
	u_int32_t	ee_errno;	/* error number */
	u_int8_t	ee_origin;	/* where the error originated */ 
	u_int8_t	ee_type;	/* type */
	u_int8_t	ee_code;	/* code */
	u_int8_t	ee_pad;
	u_int32_t	ee_info;	/* additional information */
	u_int32_t	ee_data;	/* other data */  
	/* More data may follow */ 
};

struct sockaddr *SO_EE_OFFENDER(struct sock_extended_err *);
.ta
.fi
.RE
.IP
.B ee_errno 
ˤϥ塼줿顼Υ顼ֹ椬äƤ롣
.B ee_origin
ˤϥ顼ȯΥꥸ󡦥 (origin code) äƤ롣
¾Υեɤϥץȥ¸Ǥ롣
.B SO_EE_OFFENDER
 ޥϤŪʥå˼ä
顼ȯͥåȥ֥ȤΥɥ쥹ؤΥݥ󥿤֤
ɥ쥹ξˤ
.B sockaddr 

.I sa_family 
С
.B AF_UNSPEC
ˤʤäƤ롣
.B sockaddr
¾Υեɤ̤Ǥ롣
顼ȯѥåȤΥڥɤ̾ΥǡȤϤ롣
.IP
ǤΥ顼ξˤϥɥ쥹Ϥʤ (
.B cmsghdr

.I cmsg_len 
СǥåǤ)
顼ä硢
.B MSG_ERRQUEUE 

.B msghdr
ꤵ롣
顼Ϥ줿ˤϡ
ڥǥ󥰤Ƥåȡ顼
Υ塼줿顼˴Ťƺƺ졢
ΥåκݤϤ롣
.PP
.B recvmsg
ľͿѥ᡼ο򸺤餹
.I msghdr
¤ΤѤ롣ι¤Τ
.I <sys/socket.h> 
ǰʲΤ褦Ƥ:
.IP
.RS
.nf
.ta 4n 17n 33n
struct msghdr {
	void	* msg_name;	/* optional address */
	socklen_t	msg_namelen;	/* size of address */
	struct iovec	* msg_iov;	/* scatter/gather array */
	size_t	msg_iovlen;	/* # elements in msg_iov */
	void	* msg_control;	/* ancillary data, see below */
	socklen_t	msg_controllen;	/* ancillary data buffer len */
	int	msg_flags;	/* flags on received message */
};
.ta
.fi
.RE
.PP

.I msg_name

.I msg_namelen
ϥåȤ³ƤʤΥɥ쥹ꤹ롣
̾ɬפʤˤ
.I msg_name
 null ݥ󥿤뤳ȤǤ롣
.I msg_iov

.I msg_iovlen
եɤ
.BR readv (2)
˵ҤƤ褦ʬ/ѤΥ٥ꤹ롣
.IR msg_control 
եɤ
.IR msg_controllen
Ĺ¾Υץȥå
ǡΤΥХåեؤΥݥ󥿤Ǥ롣
.B recvmsg 
ƤФ줿
.I msg_controllen
ˤ
.I msg_control
ΥХåե˳ǼǽĹäƤɬפ롣
뤫֤äƤ硢åĹäƤ롣
åη:
.PP
.RS
.nf
.ta 4n 16n 28n
struct cmsghdr {
	socklen_t	cmsg_len;	/* data byte count, including hdr */
	int	cmsg_level;	/* originating protocol */
	int	cmsg_type;	/* protocol-specific type */
/* followed by
	u_char	cmsg_data[]; */
};
.ta
.fi
.RE
.PP
ǡ
.BR cmsg (3)
줿ޥǤΤߥ٤Ǥ롣
.PP
򤢤ȡ Linux ϤǡΥᥫ˥
Unix åȾǤγĥ顼 IP ץ
ե롦ǥץμϤѤƤ롣
.PP
msghdr 
.I msg_flags
եɤ
.BR recvmsg ()
Υ꥿ꤵ롣ˤϤĤΥե饰ޤޤ롣
.TP
.B MSG_EOR
ϥ쥳ɤν (end-of-record) 򼨤
Υǡϴʥ쥳ɤ֤Ȥ򼨤 (Ūˤ
.BR SOCK_SEQPACKET 
ΥåȤǻѤ)
.TP
.B MSG_TRUNC
ǡबͿ줿Хåե礭äˡ
ǡΤϤ߽ФʬΤƤ줿Ȥ򼨤
.TP
.B MSG_CTRUNC
ǡΤΥХåե­ˡ
ǡΰΤƤ줿Ȥ򼨤
.TP
.B MSG_OOB
®ãǡӰ賰ǡȤ򼨤
.TP
.B MSG_ERRQUEUE
ǡϼʤä
åȤΥ顼塼ĥ顼Ȥ򼨤
.TP
.B MSG_DONTWAIT
֥åͭˤ롣
֥å
.B EAGAIN
֤ (
.B O_NONBLOCK

.B F_SETFL
.BR fcntl (2)
Ѥ뤳ȤˤäƤͭˤǤ)
.SH ֤
ΥϼХȿ֤
顼ξ \-1 ֤
.SH 顼
ϥåؤȯŪʥ顼Ǥ롣
¾Υ顼ؤΥץȥ롦⥸塼졢
֤뤫⤷ʤ
Υޥ˥奢򻲾Ȥ뤳ȡ
.TP
.B EBADF

.I s
ʥǥץǤ롣
.TP
.B ECONNREFUSED
⡼ȤΥۥȤǥͥåȥ³ݤ줿
(褯ͳȤƤϡ׵ᤷӥưƤʤʤ)
.TP
.B ENOTCONN
åȤ³ظץȥ뤬ƤƤꡢ
ޤ³Ƥʤ
.RB ( connect (2)

.BR accept (2)
򻲾Ȥ뤳)
.TP
.B ENOTSOCK

.I s
åȤ򻲾ȤƤʤ
.TP
.B EAGAIN
åȤ (non-blocking) ꤵƤ
ߤ褦ʾˤʤä
˻ڤ (timeout) ꤵƤ
ǡ˻ڤˤʤä
.TP
.B EINTR
ǡ˥ʥ (signal) Ƴޤ줿
.TP
.B EFAULT
ХåեؤΥݥ󥿤ץΥɥ쥹ֳؤƤ롣
.TP
.B EINVAL
ʰϤ줿
.TP
.B ENOMEM
recvmsg ΤΥ꤬ݤǤʤä
.SH 
4.4BSD (δؿ 4.2BSD Ǹ줿)
.SH 
嵭Υץȥפ glibc2 ˤäƤ롣
Single Unix Specification Ʊͤ
֤ͤη ssize_t ȤʤäƤ
( BSD 4.*  libc4  libc5  `int' ѤƤ)
.I flags
 BSD 4.* Ǥ `int' libc4  libc5 Ǥ `unsigned int' Ǥ롣
.I len
 BSD 4.* Ǥ `int'  libc4  libc5 Ǥ `size_t' Ǥ롣
.I fromlen
 BSD 4.*, libc4, libc5 Ǥ `int *' Ǥ롣
ߤ `socklen_t *'  POSIX ȯƤ줿
.BR accept (2)
⻲Ȥ뤳ȡ
.SH Ϣ
.BR fcntl (2),
.BR read (2),
.BR select (2),
.BR getsockopt (2),
.BR socket (2),
.BR cmsg (3)