NAME

       vde_addstack, vde_delstack, vde_stackcmd, vde_msocket - vde network namespace as a user library

SYNOPSIS

       #include *vdestack.h*

       struct vdestack *vde_addstack(char *vdenet, char *ifname);

       void vde_delstack(struct vdestack *stack);

       int vde_stackcmd(struct vdestack *stack, char *stackcmd);

       int vde_msocket(struct vdestack *stack,int domain, int type, int protocol);

       void vde_default_stack(struct vdestack *stack);

DESCRIPTION

       Libvdestack implements the idea of Internet of Threads through network namespaces.  By libvdestack a pro‐
       gram  can  use one (or even several) private networking protocol stack(s), thus a program can be assigned
       its own IP address(es), routing etc.

       vde_addstack
              create a private network namespace: vdenet is the URL-like specification of a vde network  as  de‐
              scribed  in :vde_plug(1).  ifname is the name of the interface in the network namespace.  When if‐
              name is NULL, the default interface :name is vde0.

       vde_delstack
              destroy a vdestack when it is no longer needed.

       vde_stackcmd
              run a command or a comma separated sequence of commands in the  private  network  namespace.   The
              purpose  of  this function is to configure the networking parameters and options (e.g. IP address,
              routing).  For security reasons, commands must be specified using full pathnames.  Do not use this
              function to start long lasting or non terminating programs, the caller waits for  the  termination
              of the command sequence.

       vde_msocket
              it  has the same semantics of socket(2) except that the socket is defined in the scope of the net‐
              work namespace whose descriptor is the first argument.  The remaining arguments are those  defined
              in socket(2).

       vde_default_stack
              define  the default stack: any successive socket(2) call will use the stack passed as parameter to
              vde_default_stack.  Use NULL to undefine the default stack.

RETURN VALUE

       vde_addstack returns a struct vdestack pointer which is used as a descriptor and thus passed as an  argu‐
       ment to the other functions of this library.  NULL is returned in case of error.

       vde_stackcmd  returns  the exit status of the command.  If the stackcmd argument is a comma separated se‐
       quence of commands, the execution terminates upon the first command whose exit status is  not  zero,  and
       the  exit  status  of  that command is returned.  Therefore when vde_stackcmd returns zero the entire se‐
       quence was successfully executed.

       On success, vde_msocket returns a valid file descriptor.  -1 is returned elseways and errno is set appro‐
       priately as described in socket(2).

NOTES

       Libvdestack fails if user namespaces have not been configured in  the  running  kernel  and  enabled  for
       users.  In Debian the sysctl knob kernel.unprivileged_userns_clone must be set to 1.

EXAMPLE

       The following excerpt of C code shows the use of libvdestack:

              ...
              int fd;
              int exit_status;
              struct vdestack *stack = vde_addstack("vde://", NULL);
              if (stack == NULL)
                  ... error management
              exit_status = vde_stackcmd(stack,
                        "/bin/ip link set vde0 up;"
                        "/bin/ip addr add 10.0.0.1/24 dev vde0;"
                        "/bin/ip route add default via 10.0.0.254");
              if (exit_status != 0)
                 ... error management
              fd = vde_msocket(stack, AF_INET, SOCK_STREAM, 0);
                 ... fd can be used in any context in which a file descriptor returned by socket(2) can.
              e.g. bind, accept, connect, read/write, send/recv ...
              vde_delstack(stack);

SEE ALSO

       socket(2), vde_plug(1)

BUGS

       Bug reports should be addressed to info@virtualsquare.org

AUTHOR

       VirtualSquare.  Project leader: Renzo Davoli.

VirtualSquare                                     December 2022                                   LIBVDESTACK(3)