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 or an address with
  74 the address family set to AF_UNPSEC (the error
  75 EAFNOSUPPORT will be harmlessly returned).
  76 .Sh RETURN VALUES
  77 If the connection or binding succeeds, 0 is returned.
  78 Otherwise a -1 is returned, and a more specific error
  79 code is stored in
  80 .Va errno .
  81 .Sh ERRORS
  82 The
  83 .Fn connect
  84 call fails if:
  85 .Bl -tag -width Er
  86 .It Bq Er EBADF
  87 .Fa S
  88 is not a valid descriptor.
  89 .It Bq Er ENOTSOCK
  90 .Fa S
  91 is a descriptor for a file, not a socket.
  92 .It Bq Er EADDRNOTAVAIL
  93 The specified address is not available on this machine.
  94 .It Bq Er EAFNOSUPPORT
  95 Addresses in the specified address family cannot be used with this socket.
  96 .It Bq Er EISCONN
  97 The socket is already connected.
  98 .It Bq Er ETIMEDOUT
  99 Connection establishment timed out without establishing a connection.
 100 .It Bq Er ECONNREFUSED
 101 The attempt to connect was forcefully rejected.
 102 .It Bq Er ENETUNREACH
 103 The network isn't reachable from this host.
 104 .It Bq Er EADDRINUSE
 105 The address is already in use.
 106 .It Bq Er EFAULT
 107 The
 108 .Fa name
 109 parameter specifies an area outside
 110 the process address space.
 111 .It Bq Er EINPROGRESS
 112 The socket is non-blocking
 113 and the connection cannot
 114 be completed immediately.
 115 It is possible to
 116 .Xr select 2
 117 for completion by selecting the socket for writing.
 118 .It Bq Er EALREADY
 119 The socket is non-blocking
 120 and a previous connection attempt
 121 has not yet been completed.
 122 .El
 123 .Pp
 124 The following errors are specific to connecting names in the UNIX domain.
 125 These errors may not apply in future versions of the UNIX IPC domain.
 126 .Bl -tag -width Er
 127 .It Bq Er ENOTDIR
 128 A component of the path prefix is not a directory.
 129 .It Bq Er ENAMETOOLONG
 130 A component of a pathname exceeded
 131 .Dv {NAME_MAX}
 132 characters, or an entire path name exceeded
 133 .Dv {PATH_MAX}
 134 characters.
 135 .It Bq Er ENOENT
 136 The named socket does not exist.
 137 .It Bq Er EACCES
 138 Search permission is denied for a component of the path prefix.
 139 .It Bq Er EACCES
 140 Write access to the named socket is denied.
 141 .It Bq Er ELOOP
 142 Too many symbolic links were encountered in translating the pathname.
 143 .El
 144 .Sh SEE ALSO
 145 .Xr accept 2 ,
 146 .Xr select 2 ,
 147 .Xr socket 2 ,
 148 .Xr getsockname 2
 149 .Sh HISTORY
 150 The
 151 .Fn connect
 152 function call appeared in
 153 .Bx 4.2 .