LIBVDESTACK(3)

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 program 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 creates a private network namespace: vdenet is the URL-like specification of a vde network as described in vde_plug(1). ifname is the name of the interface in the network namespace. When ifname is NULL, the default interface name is vde0.

vde_delstack destroys 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 has the same semantics of socket(2) except that the socket is defined in the scope of the network namespace whose descriptor is the first argument. The remaining arguments are those defined in socket(2).

vde_default_stack defines 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 argument 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 sequence 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 sequence was successfully executed.

On success, vde_msocket returns a valid file descriptor. -1 is returned elseways and errno is set appropriately 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.