connect(2) [netbsd man page]
CONNECT(2) BSD System Calls Manual CONNECT(2) NAME
connect -- initiate a connection on a socket LIBRARY
Standard C Library (libc, -lc) SYNOPSIS
#include <sys/socket.h> int connect(int s, const struct sockaddr *name, socklen_t namelen); DESCRIPTION
The parameter s 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 name, which is an address in the communications space of the socket. namelen indicates the amount of space pointed to by name, in bytes. Each communications space inter- prets the name 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 a connect() call is interrupted by a signal, it will return with errno set to EINTR and the connection attempt will proceed as if the socket was non-blocking. Subsequent calls to connect() will set errno to EALREADY. RETURN VALUES
If the connection or binding succeeds, 0 is returned. Otherwise a -1 is returned, and a more specific error code is stored in errno. ERRORS
The connect() call fails if: [EBADF] s is not a valid descriptor. [ENOTSOCK] s is a descriptor for a file, not a socket. [EADDRNOTAVAIL] The specified address is not available on this machine. [EAFNOSUPPORT] Addresses in the specified address family cannot be used with this socket. [EISCONN] The socket is already connected. [ETIMEDOUT] Connection establishment timed out without establishing a connection. [ECONNREFUSED] The attempt to connect was forcefully rejected. [ENETUNREACH] The network isn't reachable from this host. [EADDRINUSE] The address is already in use. [EFAULT] The name parameter specifies an area outside the process address space. [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 or polling the socket for writing. The success or failure of the connect operation may be deter- mined by using getsockopt(2) to read the socket error status with the SO_ERROR option at the SOL_SOCKET level. The returned socket error status is zero on success, or one of the error codes listed here on failure. [EALREADY] Either the socket is non-blocking mode or a previous call to connect() was interrupted by a signal, and the connection attempt has not yet been completed. [EINTR] The connection attempt was interrupted by a signal. The following errors are specific to connecting names in the UNIX domain. These errors may not apply in future versions of the UNIX IPC domain. [ENOTDIR] A component of the path prefix is not a directory. [ENAMETOOLONG] A component of a pathname exceeded {NAME_MAX} characters, or an entire path name exceeded {PATH_MAX} characters. [ENOENT] The named socket does not exist. [EACCES] Search permission is denied for a component of the path prefix, or write access to the named socket is denied. [ELOOP] Too many symbolic links were encountered in translating the pathname. SEE ALSO
accept(2), getsockname(2), getsockopt(2), poll(2), select(2), socket(2) HISTORY
The connect() function call appeared in 4.2BSD. BSD
May 18, 2004 BSD
Check Out this Related Man Page
connect(3SOCKET) connect(3SOCKET) NAME
connect - initiate a connection on a socket SYNOPSIS
cc [ flag ... ] file ... -lsocket -lnsl [ library ... ] #include <sys/types.h> #include <sys/socket.h> int connect(int s, const struct sockaddr *name, int namelen); The parameter s is a socket. If it is of type SOCK_DGRAM, connect() specifies the peer with which the socket is to be associated. This address is the address to which datagrams are to be sent if a receiver is not explicitly designated. This address is the only address from which datagrams are to be received. If the socket s is of type SOCK_STREAM, connect() attempts to make a connection to another socket. The other socket is specified by name. name is an address in the communication space of the socket. Each communication space interprets the name parameter in its own way. If s is not bound, then s will be bound to an address selected by the underlying transport provider. Gener- ally, stream sockets can successfully connect() only once. Datagram sockets can use connect() multiple times to change their association. Datagram sockets can dissolve the association by connecting to a null address. If the connection or binding succeeds, 0 is returned. Otherwise, -1 is returned and sets errno to indicate the error. The call fails if: EACCES Search permission is denied for a component of the path prefix of the pathname in name. EADDRINUSE The address is already in use. EADDRNOTAVAIL The specified address is not available on the remote machine. EAFNOSUPPORT Addresses in the specified address family cannot be used with this socket. EALREADY The socket is non-blocking, and a previous connection attempt has not yet been completed. EBADF s is not a valid descriptor. ECONNREFUSED The attempt to connect was forcefully rejected. The calling program should close(2) the socket descriptor, and issue another socket(3SOCKET) call to obtain a new descriptor before attempting another connect() call. EINPROGRESS The socket is non-blocking, and the connection cannot be completed immediately. You can use select(3C) to com- plete the connection by selecting the socket for writing. EINTR The connection attempt was interrupted before any data arrived by the delivery of a signal. The connection, how- ever, will be established asynchronously. EINVAL namelen is not the size of a valid address for the specified address family. EIO An I/O error occurred while reading from or writing to the file system. EISCONN The socket is already connected. ELOOP Too many symbolic links were encountered in translating the pathname in name. ENETUNREACH The network is not reachable from this host. EHOSTUNREACH The remote host is not reachable from this host. ENOENT A component of the path prefix of the pathname in name does not exist. ENOENT The socket referred to by the pathname in name does not exist. ENOSR There were insufficient STREAMS resources available to complete the operation. ENXIO The server exited before the connection was complete. ETIMEDOUT Connection establishment timed out without establishing a connection. EWOULDBLOCK The socket is marked as non-blocking, and the requested operation would block. The following errors are specific to connecting names in the UNIX domain. These errors might not apply in future versions of the UNIX IPC domain. ENOTDIR A component of the path prefix of the pathname in name is not a directory. ENOTSOCK s is not a socket. ENOTSOCK name is not a socket. EPROTOTYPE The file that is referred to by name is a socket of a type other than type s. For example, s is a SOCK_DGRAM socket, while name refers to a SOCK_STREAM socket. See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |MT-Level |Safe | +-----------------------------+-----------------------------+ close(2), accept(3SOCKET), getsockname(3SOCKET), select(3C), socket(3SOCKET), socket.h(3HEAD), attributes(5) 08 Mar 2005 connect(3SOCKET)