connect.2

<B>Digital的Unix操作系统VAX 4.2源码</B>

.\" SCCSID: @(#)connect.2	4.1	12/9/88
.TH connect 2
.SH Name
connect \- initiate a connection on a socket
.SH Syntax
.nf
.ft B
#include <sys/types.h>
#include <sys/socket.h>
.PP
.ft B
connect(s, name, namelen)
int s;
struct sockaddr *name;
int namelen;
.fi
.SH Description
.NXR "connect system call"
.NXA "connect system call" "shutdown system call"
.NXR "socket" "initiating a connection"
The
.PN connect 
call initiates a connection on a socket.
The parameter
.I s
is a socket.
If the socket is of type SOCK_DGRAM,
this call permanently specifies the peer to which
datagrams are sent.
If it is of type SOCK_STREAM,
this call attempts to make a connection to
another socket.
The other socket is specified by
.I name,
which is an address in the communications space of the socket.
Each communications space interprets the
.I name
parameter in its own way.
The size of the structure 
.I sockaddr 
is
.I namelen.
.SH Return Values
If the connection or binding succeeds, then 0 is returned.
Otherwise, a \-1 is returned, and a more specific error
code is stored in \fIerrno\fP.
.SH Diagnostics
The call fails under the following conditions:
.TP 15
[EBADF]
The
.I s
is not a valid descriptor.
.TP 15
[ENOTSOCK]
The
.I s
is a descriptor for a file, not a socket.
.TP 15
[EADDRNOTAVAIL]
The specified address is not available on this machine.
.TP 15
[EAFNOSUPPORT]
Addresses in the specified address family cannot be used with this socket.
.TP 15
[EINPROGRESS]
The connection is requested on a socket with FNDELAY set
(using
.MS fcntl 2 ).
.TP 15
[EISCONN]
The socket is already connected.
.TP 15
[ETIMEDOUT]
Connection establishment timed out without establishing a connection.
.TP 15
[ECONNREFUSED]
The attempt to connect was forcefully rejected.
.TP 15
[ENETUNREACH]
The network is not reachable from this host.
.TP 15
[EADDRINUSE]
The address is already in use.
.TP 15
[EFAULT]
The \fIname\fP parameter specifies an area outside
the process address space.
.br
.ne 3
.TP 15
[EWOULDBLOCK]
The socket is nonblocking, and the
connection cannot
be completed immediately.
You can select the socket for writing by using the
.PN select
system call
while it is connecting.
.PP
The following errors are specific to connecting names in the
ULTRIX domain:
.TP 15
[ENOTDIR]
A component of the path prefix is not a directory.
.TP 15
[ENAMETOOLONG]
A component of a pathname exceeded 255 characters, or an
entire path name exceeded 1023 characters.
.TP 15
[ENOENT]
The named socket does not exist.
.TP 15
[EACCES]
Search permission is denied for a component of the path
prefix.
.TP 15
[ELOOP]
Too many symbolic links were encountered in translating
the pathname.
.SH See Also
accept(2), fcntl(2), getsockname(2), select(2), shutdown(2), socket(2)