[mpls-linux-devel] Quagga interface vty(sh)

[Julien B. <jul...@gm...>]

Hello sir,


The more I dive into the code (of quagga, not ldp) the more I found it
really really tricky. The most difficult part was to understand how
the interface worked. And I figured out that DEFUN was used :

/* DEFUN for vty command interafce. Little bit hacky ;-). */
#define DEFUN(funcname, cmdname, cmdstr, helpstr) \
  DEFUN_CMD_FUNC_DECL(funcname) \
  DEFUN_CMD_ELEMENT(funcname, cmdname, cmdstr, helpstr, 0, 0) \
  DEFUN_CMD_FUNC_TEXT(funcname)

Which means :

#define DEFUN_CMD_FUNC_DECL(funcname) \
  static int funcname (struct cmd_element *, struct vty *, int, const char *[]);

#define DEFUN_CMD_ELEMENT(funcname, cmdname, cmdstr, helpstr, attrs, dnum) \
  struct cmd_element cmdname = \
  { \
    .string = cmdstr, \
    .func = funcname, \
    .doc = helpstr, \
    .attr = attrs, \
    .daemon = dnum, \
  };

#define DEFUN_CMD_FUNC_TEXT(funcname) \
  static int funcname \
    (struct cmd_element *self __attribute__ ((unused)), \
     struct vty *vty __attribute__ ((unused)), \
     int argc __attribute__ ((unused)), \
     const char *argv[] __attribute__ ((unused)) )


To see how the macro is used according to the interface for quagga's
usage of ldp-portable, maybe an example would be nice :
This is the first example you can find in quagga-mpls/ldpd/ldp_vty.c

DEFUN (mpls_ldp,
       mpls_ldp_cmd,
       "mpls ldp",
       "Global MPLS configuration\n"
       "Dynamic Label distribution via LDP\n")
{
    vty->node = LDP_NODE;
    vty->index = ldp_get();
    if (!vty->index) {
        if (!(vty->index = ldp_new())) {
            vty_out (vty, "Unable to create LDP instance.%s", VTY_NEWLINE);
            return CMD_WARNING;
        }
    }
    return CMD_SUCCESS;
}

And my question is : what is "mpls_ldp" or any other functions
declared by the DEFUN macro? Is this a command we can use on the
interface?

Thank you for your help.

Julien

-- 
--------------------------------------------
Julien BISCONTI <julien.bisconti(at)student.fundp.ac.be>
M.Sc. student in Computer Science, University of Namur
FUNDP, Belgium
Traineeship: UPC (Barcelona, Spain)