bird/filter/filter.c

/*
 *	Filters: utility functions
 *
 *	Copyright 1998 Pavel Machek <pavel@ucw.cz>
 *
 *	Can be freely distributed and used under the terms of the GNU GPL.
 */

#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/signal.h>
#include <setjmp.h>

#include "nest/bird.h"
#include "lib/lists.h"
#include "lib/resource.h"
#include "lib/socket.h"
#include "nest/route.h"
#include "nest/protocol.h"
#include "nest/iface.h"
#include "conf/conf.h"
#include "filter/filter.h"

struct f_inst *startup_func = NULL;

#define runtime(x) do { \
    log( L_ERR x ); \
    res.type = T_RETURN; \
    res.val.i = F_ERROR; \
    return res; \
  } while(0)

#define ARG(x,y) \
	x = interpret(what->y); \
	if (x.type == T_RETURN) \
		return x;

#define ONEARG ARG(v1, a1.p)
#define TWOARGS ARG(v1, a1.p) \
		ARG(v2, a2.p)
#define TWOARGS_C TWOARGS \
                  if (v1.type != v2.type) \
		    runtime( "Can not operate with values of incompatible types" );

static struct f_val
interpret(struct f_inst *what)
{
  struct symbol *sym;
  struct f_val v1, v2, res;

  res.type = T_VOID;
  if (!what)
    return res;

  switch(what->code) {
  case ',':
    TWOARGS;
    break;

/* Binary operators */
  case '+':
    TWOARGS_C;
    switch (res.type = v1.type) {
    case T_VOID: runtime( "Can not operate with values of type void" );
    case T_INT: res.val.i = v1.val.i + v2.val.i; break;
    default: runtime( "Usage of unknown type" );
    }
    break;
  case '/':
    TWOARGS_C;
    switch (res.type = v1.type) {
    case T_VOID: runtime( "Can not operate with values of type void" );
    case T_INT: res.val.i = v1.val.i / v2.val.i; break;
    case T_IP: if (v2.type != T_INT)
                 runtime( "Operator / is <ip>/<int>" );
               break;
    default: runtime( "Usage of unknown type" );
    }
    break;

/* Relational operators */
  case '!=':
  case '==':
    TWOARGS_C;
    res.type = T_BOOL;
    switch (v1.type) {
    case T_VOID: runtime( "Can not operate with values of type void" );
    case T_INT: res.val.i = (v1.val.i == v2.val.i); break;
    default: runtime( "Usage of unknown type" );
    }
    if (what->code == '!=')
      res.val.i = !(res.val.i);
    break;
  case '<':
    TWOARGS_C;
    res.type = T_BOOL;
    switch (v1.type) {
    case T_VOID: runtime( "Can not operate with values of type void" );
    case T_INT: res.val.i = (v1.val.i < v2.val.i); break;
    default: runtime( "Usage of unknown type" );
    }
    break;
  case '<=':
    TWOARGS_C;
    res.type = T_BOOL;
    switch (v1.type) {
    case T_VOID: runtime( "Can not operate with values of type void" );
    case T_INT: res.val.i = (v1.val.i <= v2.val.i); break;
    default: runtime( "Usage of unknown type" );
    }
    break;

/* Set */
  case 's':
    ARG(v2, a2.p);
    sym = what->a1.p;
    switch (res.type = v2.type) {
    case T_VOID: runtime( "Can not assign void values" );
    case T_INT: 
      if (sym->class != (SYM_VARIABLE | T_INT))
	runtime( "Variable of bad type" );
      sym->aux = v2.val.i; 
      break;
    }
    break;

  case 'c':
    res.type = what->a1.i;
    res.val.i = (int) what->a2.p;
    break;
  case 'i':
    res.type = what->a1.i;
    res.val.i = * ((int *) what->a2.p);
    break;
  case 'p':
    ONEARG;
    switch (v1.type) {
    case T_VOID: printf( "(void)" ); break;
    case T_INT: printf( "%d ", v1.val.i ); break;
    case T_STRING: printf( "%s", v1.val.i ); break;
    default: runtime( "Print of variable of unknown type" );
    }
    break;
  case '?':	/* ? has really strange error value, so we can implement if ... else nicely :-) */
    ONEARG;
    if (v1.type != T_BOOL)
      runtime( "If requires bool expression" );
    if (v1.val.i) {
      ARG(res,a2.p);
      res.val.i = 0;
    } else res.val.i = 1;
    res.type = T_BOOL;
    break;
  case '0':
    printf( "No operation\n" );
    break;
  case 'p,':
    ONEARG;
    printf( "\n" );

    switch (what->a2.i) {
    case F_QUITBIRD:
      die( "Filter asked me to die" );
    case F_ACCEPT:
      /* Should take care about turning ACCEPT into MODIFY */
    case F_ERROR:
    case F_REJECT:
      res.type = T_RETURN;
      res.val.i = what->a1.i;
      break;
    case F_NOP:
      break;
    default:
      bug( "unknown return type: can not happen");
    }
    break;
  default:
    bug( "Unknown instruction %d (%c)", what->code, what->code & 0xff);
  }
  if (what->next)
    return interpret(what->next);
  return res;
}

int
f_run(struct filter *filter, struct rte **rte, struct ea_list **tmp_attrs, struct linpool *tmp_pool)
{
  struct f_inst *inst;
  struct f_val res;
  debug( "Running filter `%s'...", filter->name );

  inst = filter->root;
  res = interpret(inst);
  if (res.type != T_RETURN)
    return F_ERROR;
  debug( "done (%d)\n", res.val.i );
  return res.val.i;
}


void
filters_postconfig(void)
{
  struct f_val res;
  if (startup_func) {
    printf( "Launching startup function...\n" );
    res = interpret(startup_func);
    if (res.type == F_ERROR)
      die( "Startup function resulted in error." );
    printf( "done\n" );
  }
}