NAME

       vde_open,  vde_recv,  vde_send,  vde_send,  vde_recv,  vde_close  -  connect  clients  to  a VDE (virtual
       distributed ethernet) network

SYNOPSIS

       #include <libvdeplug.h>
       VDECONN *vde_open(char *vde_url,char *descr, struct vde_open_args *open_args);
       ssize_t vde_recv(VDECONN *conn,void *buf,size_t len,int flags);
       ssize_t vde_send(VDECONN *conn,const void *buf,size_t len,int flags);
       int vde_datafd(VDECONN *conn);
       int vde_ctlfd(VDECONN *conn);
       int vde_close(VDECONN *conn);

       These functions are provided by libvdeplug. Link with -lvdeplug.

DESCRIPTION

       Libvdeplug is the library used by clients to join a VDE network. It is a generic library  which  can  use
       several  different  implementations  for  virtual  distributed  networks.  In fact vde_url has the syntax
       module://specific_address.  e.g. vde:///home/user/myswitch or vxvde://239.0.0.1.  The default  module  is
       libvdeplug_vde(1)  (connection  to  a  vde_switch(1))  and can be omitted. e.g. /home/user/myswitch means
       vde:///home/user/myswitch

       vde_open opens a VDE connection: vde_url is the vde network identifier as described here above and  descr
       is  a  description of this connection (it can be useful to identify this connection in the port list of a
       switch). open_args has been left for backwards compatibility but can be safely set to  NULL  as  all  the
       options previosly defined as fields of struct vde_open_args are now parameters of the VDE modules (can be
       defined using a module specific syntax in vde_url).

       vde_recv receives a packet from the VDE connection.

       vde_send sends a packet to the VDE connection.

       vde_datafd returns the data file descriptor of the connection: this descriptor can be used in poll(2)  or
       select(2)  (or  similar)  system  calls. When this descriptor signals data available for reading vde_recv
       will not block.

       vde_ctlfd returns the control file descriptor of the connection. Not  all  the  modules  support  control
       descritors,  but when it is valid descriptor (greater or equal than 0) can be used to check if the remote
       endpoint (switch or peer) hanged up. No data can be sent or received using the control  file  descriptor,
       it returns an end-of-file condition when the connection get closed (zero length on reading).

       vde_close closes a vde connections.

RETURN VALUE

       vde_open  returns  the  descriptor  of  the  VDE connection which is used as a parameter of all the other
       functions.  NULL is returned in case of error.

       vde_recv returns the length of the packet received. It should never be less then 14 bytes (the length  of
                 an  ethernet  header).  It returns -1 in case of error, it may return 1 to notify that a packet
       has been received but it must be dropped (e.g. the sender was not allowed to send that packet).

       vde_send returns the number of bytes sent. It returns -1 in case of error.

       vde_datafd and vde_ctlfd returns a file descriptor and  -1 in case of error.

       vde_datafd returns 0 in case of success and  -1 in case of error.

NOTICE

       Virtual Distributed Ethernet is not related in any way with  www.vde.com  ("Verband  der  Elektrotechnik,
       Elektronik und Informationstechnik" i.e. the German "Association for Electrical, Electronic & Information
       Technologies").

SEE ALSO

       vde_plug(1), vde_switch(1)

BUGS

       Bug reports should be addressed to <info@virtualsquare.org>

AUTHOR

       Renzo Davoli <renzo@cs.unibo.it>