bsd/man/man2/connect.2

   1 .\"     $NetBSD: connect.2,v 1.8 1995/10/12 15:40:48 jtc Exp $
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  33 .\"
  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 .Fo connect
  47 .Fa "int socket"
  48 .Fa "const struct sockaddr *address"
  49 .Fa "socklen_t address_len"
  50 .Fc
  51 .Sh DESCRIPTION
  52 The parameter
  53 .Fa socket
  54 is a socket.
  55 If it is of type
  56 .Dv SOCK_DGRAM ,
  57 this call specifies the peer with which the socket is to be associated;
  58 this address is that to which datagrams are to be sent,
  59 and the only address from which datagrams are to be received.
  60 If the socket is of type
  61 .Dv SOCK_STREAM ,
  62 this call attempts to make a connection to
  63 another socket.
  64 The other socket is specified by
  65 .Fa address ,
  66 which is an address in the communications space of the socket.
  67 .Pp
  68 Each communications space interprets the
  69 .Fa address
  70 parameter in its own way.
  71 Generally, stream sockets may successfully
  72 .Fn connect
  73 only once; datagram sockets may use
  74 .Fn connect
  75 multiple times to change their association.
  76 Datagram sockets may dissolve the association
  77 by connecting to an invalid address, such as a null address
  78 or an address with
  79 the address family set to
  80 .Dv AF_UNSPEC
  81 (the error
  82 .Dv EAFNOSUPPORT
  83 will be harmlessly returned).
  84 .Sh RETURN VALUES
  85 Upon successful completion, a value of 0 is returned.
  86 Otherwise, a value of -1 is returned and the global integer variable
  87 .Va errno
  88 is set to indicate the error.
  89 .Sh ERRORS
  90 The
  91 .Fn connect
  92 system call will fail if:
  93 .Bl -tag -width Er
  94 .\" ==========
  95 .It Bq Er EACCES
  96 The destination address is a broadcast address and the
  97 socket option
  98 .Dv SO_BROADCAST
  99 is not set.
 100 .\" ==========
 101 .It Bq Er EADDRINUSE
 102 The address is already in use.
 103 .\" ==========
 104 .It Bq Er EADDRNOTAVAIL
 105 The specified address is not available on this machine.
 106 .\" ==========
 107 .It Bq Er EAFNOSUPPORT
 108 Addresses in the specified address family cannot be used with this socket.
 109 .\" ==========
 110 .It Bq Er EALREADY
 111 The socket is non-blocking
 112 and a previous connection attempt
 113 has not yet been completed.
 114 .\" ==========
 115 .It Bq Er EBADF
 116 .Fa socket
 117 is not a valid descriptor.
 118 .\" ==========
 119 .It Bq Er ECONNREFUSED
 120 The attempt to connect was ignored
 121 (because the target is not listening for connections)
 122 or explicitly rejected.
 123 .\" ==========
 124 .It Bq Er EFAULT
 125 The
 126 .Fa address
 127 parameter specifies an area outside
 128 the process address space.
 129 .\" ==========
 130 .It Bq Er EHOSTUNREACH
 131 The target host cannot be reached (e.g., down, disconnected).
 132 .\" ==========
 133 .It Bq Er EINPROGRESS
 134 The socket is non-blocking
 135 and the connection cannot
 136 be completed immediately.
 137 It is possible to
 138 .Xr select 2
 139 for completion by selecting the socket for writing.
 140 .\" ==========
 141 .It Bq Er EINTR
 142 Its execution was interrupted by a signal.
 143 .\" ==========
 144 .It Bq Er EINVAL
 145 An invalid argument was detected
 146 (e.g.,
 147 .Fa address_len
 148 is not valid for the address family,
 149 the specified address family is invalid).
 150 .\" ==========
 151 .It Bq Er EISCONN
 152 The socket is already connected.
 153 .\" ==========
 154 .It Bq Er ENETDOWN
 155 The local network interface is not functioning.
 156 .\" ==========
 157 .It Bq Er ENETUNREACH
 158 The network isn't reachable from this host.
 159 .\" ==========
 160 .It Bq Er ENOBUFS
 161 The system call was unable to allocate a needed memory buffer.
 162 .\" ==========
 163 .It Bq Er ENOTSOCK
 164 .Fa socket
 165 is not a file descriptor for a socket.
 166 .\" ==========
 167 .It Bq Er EOPNOTSUPP
 168 Because
 169 .Fa socket
 170 is listening, no connection is allowed.
 171 .\" ==========
 172 .It Bq Er EPROTOTYPE
 173 .Fa address
 174 has a different type than the socket
 175 that is bound to the specified peer address.
 176 .\" ==========
 177 .It Bq Er ETIMEDOUT
 178 Connection establishment timed out without establishing a connection.
 179 .El
 180 .Pp
 181 The following errors are specific to connecting names in the UNIX domain.
 182 These errors may not apply in future versions of the UNIX IPC domain.
 183 .Bl -tag -width Er
 184 .\" ==========
 185 .It Bq Er EACCES
 186 Search permission is denied for a component of the path prefix.
 187 .\" ==========
 188 .It Bq Er EACCES
 189 Write access to the named socket is denied.
 190 .\" ==========
 191 .It Bq Er EIO
 192 An I/O error occurred while reading from or writing to the file system.
 193 .\" ==========
 194 .It Bq Er ELOOP
 195 Too many symbolic links were encountered in translating the pathname.
 196 This is taken to be indicative of a looping symbolic link.
 197 .\" ==========
 198 .It Bq Er ENAMETOOLONG
 199 A component of a pathname exceeded
 200 .Dv {NAME_MAX}
 201 characters, or an entire path name exceeded
 202 .Dv {PATH_MAX}
 203 characters.
 204 .\" ==========
 205 .It Bq Er ENOENT
 206 The named socket does not exist.
 207 .\" ==========
 208 .It Bq Er ENOTDIR
 209 A component of the path prefix is not a directory.
 210 .El
 211 .Sh LEGACY SYNOPSIS
 212 .Fd #include <sys/types.h>
 213 .Fd #include <sys/socket.h>
 214 .Pp
 215 The include file
 216 .In sys/types.h
 217 is necessary.
 218 .Sh SEE ALSO
 219 .Xr accept 2 ,
 220 .Xr getsockname 2 ,
 221 .Xr select 2 ,
 222 .Xr socket 2 ,
 223 .Xr compat 5
 224 .Sh HISTORY
 225 The
 226 .Fn connect
 227 function call appeared in
 228 .Bx 4.2 .