SYS_CONNECT


Initiates a connection on a socket.

Arguments:

1st Socket descriptor.
2nd Pointer to a properly initialized sockaddr_* (depends on the address family) structure.

If the socket specified by 1st argument is of type SOCK_DGRAM then sockaddr_* 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 the socket that is bound to the address specified by 2nd argument.
3rd Size of the structure pointed by 2nd argument.

Return values

If the system call succeeds the return value is 0.
If the system call fails the return value is one of the following errno values:

-EACCES For Unix domain sockets, which are identified by pathname: Write permission is denied on the socket file, or search permission is denied for one of the directories in the path prefix.
-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.
-EADDRINUSE Local address is already in use.
-EAFNOSUPPORT The passed address didn't have the correct address family in its sa_family field.
-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 (man 7 ip) on how to increase the number of local ports.
-EALREADY The socket is non-blocking and a previous connection attempt has not yet been completed.
-EBADF The file descriptor is not a valid index in the descriptor table.
-ECONNREFUSED No one listening on the remote address.
-EFAULT The socket structure address is outside the user's address space.
-EINPROGRESS The socket is non-blocking and the connection cannot be completed immediately. It is possible to sys_select or sys_poll for completion by selecting the socket for writing. After sys_select indicates writability, use SYS_SETSOCKOPT to read the SO_ERROR option at level SOL_SOCKET to determine whether SYS_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).
-EINTR The system call was interrupted by a signal that was caught.
-EISCONN The socket is already connected.
-ENETUNREACH Network is unreachable.
-ENOTSOCK The file descriptor is not associated with a socket.
-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.

Remarks

Generally, connection-based protocol sockets may successfully SYS_CONNECT only once; connectionless protocol sockets may use SYS_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.

Compatibility

n/a