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>