The connect() function requests a connection to be made on a socket. The function takes the following arguments:
-
socket
- Specifies the file descriptor associated with the socket.
-
address
- Points to a sockaddr structure containing the peer address. The length and format of the address depend on the address family of the socket.
-
address_len
- Specifies the length of the sockaddr structure pointed to by the address argument.
If the socket has not already been bound to a local address, connect() will bind it to an address which, unless the socket's address family is AF_UNIX, is an unused local address.
If the initiating socket is not connection-mode, then connect() sets the socket's peer address, but no connection is made. For SOCK_DGRAM sockets, the peer address identifies where all datagrams are sent on subsequent send(3XNET) calls, and limits the remote sender for subsequent recv(3XNET) calls. If address is a null address
for the protocol, the socket's peer address will be reset.
If the initiating socket is connection-mode, then connect() attempts to establish a connection to the address specified by the address argument.
If the connection cannot be established immediately and O_NONBLOCK is not set for the file descriptor for the socket, connect() will block for up to an unspecified timeout interval until the connection is established. If the timeout interval expires before the connection is established, connect() will fail and the connection attempt will be aborted. If connect() is interrupted by a signal that is caught while blocked waiting to establish a connection, connect() will fail and set errno to EINTR,
but the connection request will not be aborted, and the connection will be established asynchronously.
If the connection cannot be established immediately and O_NONBLOCK is set for the file descriptor for the socket, connect() will fail and set errno to EINPROGRESS, but the connection request will not be aborted, and the connection will
be established asynchronously. Subsequent calls to connect() for the same socket, before the connection is established, will fail and set errno to EALREADY.
When the connection has been established asynchronously, select(3C) and poll(2) will indicate that the file descriptor for the socket is ready for writing.
The socket in use may require the process to have appropriate privileges to use the connect() function.
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