connect - initiate a connection on a socket
int connect(int sockfd, struct sockaddr *serv_addr, int
The parameter sockfd is a socket. If it is of type
SOCK_DGRAM, this call specifies the peer with which the
socket is to be associated; this address is that to which
datagrams are to be sent, and the only address from which
datagrams are to be received. If the socket is of type
SOCK_STREAM , this call attempts to make a connection to
another socket. The other socket is specified by serv_addr,
which is an address in the communications space of the
socket. Each communications space interprets the serv_addr,
parameter in its own way. Generally, stream sockets may
successfully connect only once; datagram sockets may use
connect multiple times to change their association.
Datagram sockets may dissolve the association by connecting
to an invalid address, such as a null address.
If the connection or binding succeeds, zero is returned. On
error, -1 is returned, and errno is set appropriately.
The following are general socket errors only. There may be
other domain-specific error codes.
EBADF Bad descriptor.
EFAULT The socket structure address is outside your address
The descriptor is not associated with a socket.
EISCONN The socket is already connected.
Connection refused at server.
Timeout while attempting connection.
Network is unreachable.
Address is already in use.
The socket is non-blocking and the connection cannot
be completed immediately. It is possible to
select(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
above, explaining the reason for the failure).
The socket is non-blocking and a previous connection
attempt has not yet been completed.
SVr4, 4.4BSD (the connect function first appeared in BSD
4.2). SVr4 documents additional general error codes EAD-
DRNOTAVAIL, EINVAL, EAFNOSUPPORT, EALREADY, EINTR, EPROTO-
TYPE, ENOSR. It also documents many additional error condi-
tions not described here.
accept(2), bind(2), listen(2), socket(2), getsockname(2)