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CONNECT
!!!CONNECT
NAME
SYNOPSIS
DESCRIPTION
RETURN VALUE
ERRORS
CONFORMING TO
NOTE
BUGS
SEE ALSO
----
!!NAME


connect - initiate a connection on a socket
!!SYNOPSIS


__#include __
#include __


__int connect(int__ ''sockfd''__, const struct
sockaddr *__''serv_addr''__, socklen_t__
''addrlen''__);__
!!DESCRIPTION


The file descriptor ''sockfd'' must refer to a socket. If
the socket is of type __SOCK_DGRAM__ then the
''serv_addr'' address is the address to which datagrams
are sent by default, and the only address from which
datagrams are received. If the socket is of type
__SOCK_STREAM__ or __SOCK_SEQPACKET__, this call
attempts to make a connection to another socket. The other
socket is specified by ''serv_addr'', which is an address
(of length ''addrlen'') in the communications space of
the socket. Each communications space interprets the
''serv_addr'' parameter in its own way.


Generally, connection-based protocol sockets may
successfully __connect__ only once; connectionless
protocol sockets may use __connect__ multiple times to
change their association. Connectionless sockets may
dissolve the association by connecting to an address with
the ''sa_family'' member of __sockaddr__ set to
__AF_UNSPEC__.
!!RETURN VALUE


If the connection or binding succeeds, zero is returned. On
error, -1 is returned, and ''errno'' is set
appropriately.
!!ERRORS


The following are general socket errors only. There may be
other domain-specific error codes.


__EBADF__


The file descriptor is not a valid index in the descriptor
table.


__EFAULT__


The socket structure address is outside the user's address
space.


__ENOTSOCK__


The file descriptor is not associated with a
socket.


__EISCONN__


The socket is already connected.


__ECONNREFUSED__


No one listening on the remote address.


__ETIMEDOUT__


Timeout while attempting connection. The server may be too
busy to accept new connections. Note that for IP sockets the
timeout may be very long when syncookies are enabled on the
server.


__ENETUNREACH__


Network is unreachable.


__EADDRINUSE__


Local address is already in use.


__EINPROGRESS__


The socket is non-blocking and the connection cannot be
completed immediately. It is possible to select(2) or
poll(2) for completion by selecting the socket for
writing. After __select__ indicates writability, use
getsockopt(2) to read the __SO_ERROR__ option at
level __SOL_SOCKET__ to determine whether __connect__
completed successfully (__SO_ERROR__ is zero) or
unsuccessfully (__SO_ERROR__ is one of the usual error
codes listed here, explaining the reason for the
failure).


__EALREADY__


The socket is non-blocking and a previous connection attempt
has not yet been completed.


__EAGAIN__


No more free local ports or insufficient entries in the
routing cache. For __PF_INET__ see the
__net.ipv4.ip_local_port_range__ sysctl in ip(7)
on how to increase the number of local ports.


__EAFNOSUPPORT__


The passed address didn't have the correct address family in
its ''sa_family'' field.


__EACCES, EPERM__


The user tried to connect to a broadcast address without
having the socket broadcast flag enabled or the connection
request failed because of a local firewall
rule.
!!CONFORMING TO


SVr4, 4.4BSD (the __connect__ function first appeared in
BSD 4.2). SVr4 documents the additional general error codes
__EADDRNOTAVAIL__, __EINVAL__, __EAFNOSUPPORT__,
__EALREADY__, __EINTR__, __EPROTOTYPE__, and
__ENOSR__. It also documents many additional error
conditions not described here.
!!NOTE


The third argument of __connect__ is in reality an int
(and this is what BSD 4.* and libc4 and libc5 have). Some
POSIX confusion resulted in the present socklen_t. The draft
standard has not been adopted yet, but glibc2 already
follows it and also has socklen_t. See also
accept(2).
!!BUGS


Unconnecting a socket by calling __connect__ with a
__AF_UNSPEC__ address is not yet
implemented.
!!SEE ALSO


accept(2), bind(2), listen(2),
socket(2), getsockname(2)
----
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Version 1, saved on Tuesday, June 4, 2002 12:23:40 am by "perry"
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