bsd/man/man2/connect.2

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  34 .\"     @(#)connect.2   8.1 (Berkeley) 6/4/93
  35 .\"
  36 .Dd June 4, 1993
  37 .Dt CONNECT 2
  38 .Os BSD 4.2
  39 .Sh NAME
  40 .Nm connect
  41 .Nd initiate a connection on a socket
  42 .Sh SYNOPSIS
  43 .Fd #include <sys/types.h>
  44 .Fd #include <sys/socket.h>
  45 .Ft int
  46 .Fn connect "int s" "const struct sockaddr *name" "int namelen"
  47 .Sh DESCRIPTION
  48 The parameter
  49 .Fa s
  50 is a socket.
  51 If it is of type
  52 .Dv SOCK_DGRAM ,
  53 this call specifies the peer with which the socket is to be associated;
  54 this address is that to which datagrams are to be sent,
  55 and the only address from which datagrams are to be received.
  56 If the socket is of type
  57 .Dv SOCK_STREAM ,
  58 this call attempts to make a connection to
  59 another socket.
  60 The other socket is specified by
  61 .Fa name ,
  62 which is an address in the communications space of the socket.
  63 Each communications space interprets the
  64 .Fa name
  65 parameter in its own way.
  66 Generally, stream sockets may successfully
  67 .Fn connect
  68 only once; datagram sockets may use
  69 .Fn connect
  70 multiple times to change their association.
  71 Datagram sockets may dissolve the association
  72 by connecting to an invalid address, such as a null address.
  73 .Sh RETURN VALUES
  74 If the connection or binding succeeds, 0 is returned.
  75 Otherwise a -1 is returned, and a more specific error
  76 code is stored in
  77 .Va errno .
  78 .Sh ERRORS
  79 The
  80 .Fn connect
  81 call fails if:
  82 .Bl -tag -width Er
  83 .It Bq Er EBADF
  84 .Fa S
  85 is not a valid descriptor.
  86 .It Bq Er ENOTSOCK
  87 .Fa S
  88 is a descriptor for a file, not a socket.
  89 .It Bq Er EADDRNOTAVAIL
  90 The specified address is not available on this machine.
  91 .It Bq Er EAFNOSUPPORT
  92 Addresses in the specified address family cannot be used with this socket.
  93 .It Bq Er EISCONN
  94 The socket is already connected.
  95 .It Bq Er ETIMEDOUT
  96 Connection establishment timed out without establishing a connection.
  97 .It Bq Er ECONNREFUSED
  98 The attempt to connect was forcefully rejected.
  99 .It Bq Er ENETUNREACH
 100 The network isn't reachable from this host.
 101 .It Bq Er EADDRINUSE
 102 The address is already in use.
 103 .It Bq Er EFAULT
 104 The
 105 .Fa name
 106 parameter specifies an area outside
 107 the process address space.
 108 .It Bq Er EINPROGRESS
 109 The socket is non-blocking
 110 and the connection cannot
 111 be completed immediately.
 112 It is possible to
 113 .Xr select 2
 114 for completion by selecting the socket for writing.
 115 .It Bq Er EALREADY
 116 The socket is non-blocking
 117 and a previous connection attempt
 118 has not yet been completed.
 119 .El
 120 .Pp
 121 The following errors are specific to connecting names in the UNIX domain.
 122 These errors may not apply in future versions of the UNIX IPC domain.
 123 .Bl -tag -width Er
 124 .It Bq Er ENOTDIR
 125 A component of the path prefix is not a directory.
 126 .It Bq Er ENAMETOOLONG
 127 A component of a pathname exceeded
 128 .Dv {NAME_MAX}
 129 characters, or an entire path name exceeded
 130 .Dv {PATH_MAX}
 131 characters.
 132 .It Bq Er ENOENT
 133 The named socket does not exist.
 134 .It Bq Er EACCES
 135 Search permission is denied for a component of the path prefix.
 136 .It Bq Er EACCES
 137 Write access to the named socket is denied.
 138 .It Bq Er ELOOP
 139 Too many symbolic links were encountered in translating the pathname.
 140 .El
 141 .Sh SEE ALSO
 142 .Xr accept 2 ,
 143 .Xr select 2 ,
 144 .Xr socket 2 ,
 145 .Xr getsockname 2
 146 .Sh HISTORY
 147 The
 148 .Fn connect
 149 function call appeared in
 150 .Bx 4.2 .