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