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bird/filter/filter.c

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/*
* Filters: utility functions
*
* Copyright 1998 Pavel Machek <pavel@ucw.cz>
*
* Can be freely distributed and used under the terms of the GNU GPL.
*
*/
/**
* DOC: Filters
*
* Filter consists of tree of &f_inst structures, one structure per
* "instruction". Each &f_inst contains code, aux value which is
* usually type of data this instruction operates on, and two generic
* arguments (a1, a2). Some instructinos contain pointer(s) to other
* instructions in their (a1, a2) fields.
*
* Filters use structure &f_val for its variables. Each &f_val
* contains type and value. Types are constants prefixed with %T_. Few
* of types are special; %T_RETURN can be or-ed with type to indicate
* that return from function/from whole filter should be
* forced. Important thing about &f_val s is that they may be copied
* with simple =. That's fine for all currently defined types: strings
* are read-only (and therefore okay), paths are copied for each
* operation (okay too).
*/
#undef LOCAL_DEBUG
#include "nest/bird.h"
#include "lib/lists.h"
#include "lib/resource.h"
#include "lib/socket.h"
#include "lib/string.h"
#include "lib/unaligned.h"
#include "nest/route.h"
#include "nest/protocol.h"
#include "nest/iface.h"
#include "nest/attrs.h"
#include "conf/conf.h"
#include "filter/filter.h"
#define P(a,b) ((a<<8) | b)
#define CMP_ERROR 999
static int
pm_path_compare(struct f_path_mask *m1, struct f_path_mask *m2)
{
while (1) {
if ((!m1) || (!m2))
return !((!m1) && (!m2));
m1 = m1->next;
m2 = m2->next;
}
}
/* Compare two values, returns -1, 0, 1 compared, ERROR 999 */
int
val_compare(struct f_val v1, struct f_val v2)
{
if ((v1.type == T_VOID) && (v2.type == T_VOID))
return 0;
if (v1.type == T_VOID) /* Hack for else */
return -1;
if (v2.type == T_VOID)
return 1;
if (v1.type != v2.type) {
debug( "Types do not match in val_compare\n" );
return CMP_ERROR;
}
switch (v1.type) {
case T_ENUM:
case T_INT:
case T_PAIR:
if (v1.val.i == v2.val.i) return 0;
if (v1.val.i < v2.val.i) return -1;
return 1;
case T_IP:
case T_PREFIX:
return ipa_compare(v1.val.px.ip, v2.val.px.ip);
case T_PATH_MASK:
return pm_path_compare(v1.val.path_mask, v2.val.path_mask);
default:
debug( "Compare of unkown entities: %x\n", v1.type );
return CMP_ERROR;
}
}
int
val_simple_in_range(struct f_val v1, struct f_val v2)
{
if ((v1.type == T_PATH) && (v2.type == T_PATH_MASK))
return as_path_match(v1.val.ad, v2.val.path_mask);
if ((v1.type == T_PAIR) && (v2.type == T_CLIST))
return int_set_contains(v2.val.ad, v1.val.i);
if ((v1.type == T_IP) && (v2.type == T_PREFIX))
return !(ipa_compare(ipa_and(v2.val.px.ip, ipa_mkmask(v2.val.px.len)), ipa_and(v1.val.px.ip, ipa_mkmask(v2.val.px.len))));
if ((v1.type == T_PREFIX) && (v2.type == T_PREFIX)) {
ip_addr mask;
if (v1.val.px.len & (LEN_PLUS | LEN_MINUS | LEN_RANGE))
return CMP_ERROR;
mask = ipa_mkmask( v2.val.px.len & LEN_MASK );
if (ipa_compare(ipa_and(v2.val.px.ip, mask), ipa_and(v1.val.px.ip, mask)))
return 0;
if ((v2.val.px.len & LEN_MINUS) && (v1.val.px.len <= (v2.val.px.len & LEN_MASK)))
return 0;
if ((v2.val.px.len & LEN_PLUS) && (v1.val.px.len < (v2.val.px.len & LEN_MASK)))
return 0;
if ((v2.val.px.len & LEN_RANGE) && ((v1.val.px.len < (0xff & (v2.val.px.len >> 16)))
|| (v1.val.px.len > (0xff & (v2.val.px.len >> 8)))))
return 0;
return 1;
}
return CMP_ERROR;
}
int
val_in_range(struct f_val v1, struct f_val v2)
{
int res;
res = val_simple_in_range(v1, v2);
if (res != CMP_ERROR)
return res;
if (((v1.type == T_INT) || ((v1.type == T_IP) || (v1.type == T_PREFIX)) && (v2.type == T_SET))) {
struct f_tree *n;
n = find_tree(v2.val.t, v1);
if (!n)
return 0;
return !! (val_simple_in_range(v1, n->from)); /* We turn CMP_ERROR into compared ok, and that's fine */
}
return CMP_ERROR;
}
static void
tree_print(struct f_tree *t)
{
if (!t) {
debug( "() " );
return;
}
debug( "[ " );
tree_print( t->left );
debug( ", " ); val_print( t->from ); debug( ".." ); val_print( t->to ); debug( ", " );
tree_print( t->right );
debug( "] " );
}
void
val_print(struct f_val v)
{
char buf[2048];
char buf2[1024];
#define PRINTF(a...) bsnprintf( buf, 2040, a )
buf[0] = 0;
switch (v.type) {
case T_VOID: PRINTF( "(void)" ); break;
case T_BOOL: PRINTF( v.val.i ? "TRUE" : "FALSE" ); break;
case T_INT: PRINTF( "%d ", v.val.i ); break;
case T_STRING: PRINTF( "%s", v.val.s ); break;
case T_IP: PRINTF( "%I", v.val.px.ip ); break;
case T_PREFIX: PRINTF( "%I/%d", v.val.px.ip, v.val.px.len ); break;
case T_PAIR: PRINTF( "(%d,%d)", v.val.i >> 16, v.val.i & 0xffff ); break;
case T_SET: tree_print( v.val.t ); PRINTF( "\n" ); break;
case T_ENUM: PRINTF( "(enum %x)%d", v.type, v.val.i ); break;
case T_PATH: as_path_format(v.val.ad, buf2, 1020); PRINTF( "(path %s)", buf2 ); break;
case T_CLIST: int_set_format(v.val.ad, buf2, 1020); PRINTF( "(clist %s)", buf2 ); break;
case T_PATH_MASK: debug( "(pathmask " ); { struct f_path_mask *p = v.val.s; while (p) { debug("%d ", p->val); p=p->next; } debug(")" ); } break;
default: PRINTF( "[unknown type %x]", v.type );
#undef PRINTF
}
debug( buf );
}
static struct rte **f_rte, *f_rte_old;
static struct linpool *f_pool;
static struct ea_list **f_tmp_attrs;
static int f_flags;
static rta *f_rta_copy;
#define runtime(x) do { \
log( L_ERR "filters, line %d: %s", what->lineno, 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;
int i,j,k;
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;
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;
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 */
#define COMPARE(x) \
TWOARGS_C; \
res.type = T_BOOL; \
i = val_compare(v1, v2); \
if (i==CMP_ERROR) \
runtime( "Error in comparation" ); \
res.val.i = (x); \
break;
case P('!','='): COMPARE(i!=0);
case P('=','='): COMPARE(i==0);
case '<': COMPARE(i==-1);
case P('<','='): COMPARE(i!=1);
case '!':
ONEARG;
if (v1.type != T_BOOL)
runtime( "not applied to non-boolean" );
res = v1;
res.val.i = !res.val.i;
break;
case '~':
TWOARGS;
res.type = T_BOOL;
res.val.i = val_in_range(v1, v2);
if (res.val.i == CMP_ERROR)
runtime( "~ applied on unknown type pair" );
break;
case P('d','e'):
ONEARG;
res.type = T_BOOL;
res.val.i = (v1.type != T_VOID);
break;
/* Set to indirect value, a1 = variable, a2 = value */
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_ENUM:
case T_INT:
case T_IP:
case T_PREFIX:
case T_PAIR:
case T_PATH:
case T_CLIST:
case T_PATH_MASK:
if (sym->class != (SYM_VARIABLE | v2.type))
runtime( "Variable of bad type" );
* (struct f_val *) sym->aux2 = v2;
break;
default:
bug( "Set to invalid type" );
}
break;
case 'c': /* integer (or simple type) constant */
res.type = what->aux;
res.val.i = what->a2.i;
break;
case 'C':
res = * ((struct f_val *) what->a1.p);
break;
case 'p':
ONEARG;
val_print(v1);
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':
debug( "No operation\n" );
break;
case P('p',','):
ONEARG;
if (what->a2.i == F_NOP || (what->a2.i != F_NONL && what->a1.p))
debug( "\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: /* FIXME (noncritical) Should print complete route along with reason to reject route */
res.type = T_RETURN;
res.val.i = what->a2.i;
return res; /* We have to return now, no more processing. */
case F_NONL:
case F_NOP:
break;
default:
bug( "unknown return type: can not happen");
}
break;
case 'a': /* rta access */
{
struct rta *rta = (*f_rte)->attrs;
res.type = what->aux;
switch(res.type) {
case T_IP:
res.val.px.ip = * (ip_addr *) ((char *) rta + what->a2.i);
break;
case T_ENUM:
res.val.i = * ((char *) rta + what->a2.i);
break;
case T_PREFIX: /* Warning: this works only for prefix of network */
{
res.val.px.ip = (*f_rte)->net->n.prefix;
res.val.px.len = (*f_rte)->net->n.pxlen;
break;
}
default:
bug( "Invalid type for rta access (%x)", res.type );
}
}
break;
case P('e','a'): /* Access to extended attributes */
{
eattr *e = NULL;
if (!(f_flags & FF_FORCE_TMPATTR))
e = ea_find( (*f_rte)->attrs->eattrs, what->a2.i );
if (!e)
e = ea_find( (*f_tmp_attrs), what->a2.i );
if ((!e) && (f_flags & FF_FORCE_TMPATTR))
e = ea_find( (*f_rte)->attrs->eattrs, what->a2.i );
switch (what->aux & EAF_TYPE_MASK) {
case EAF_TYPE_INT:
if (!e) {
res.type = T_VOID;
break;
}
res.type = T_INT;
res.val.i = e->u.data;
break;
case EAF_TYPE_AS_PATH:
if (!e) {
res.type = T_VOID;
break;
}
res.type = T_PATH;
res.val.ad = e->u.ptr;
break;
case EAF_TYPE_INT_SET:
if (!e) {
res.type = T_CLIST;
res.val.ad = adata_empty(f_pool);
break;
}
res.type = T_CLIST;
res.val.ad = e->u.ptr;
break;
default:
bug("Unknown type in e,a\n");
}
}
break;
case P('e','S'):
ONEARG;
{
struct ea_list *l = lp_alloc(f_pool, sizeof(struct ea_list) + sizeof(eattr));
l->next = NULL;
l->flags = EALF_SORTED;
l->count = 1;
l->attrs[0].id = what->a2.i;
l->attrs[0].flags = 0;
l->attrs[0].type = what->aux | EAF_ORIGINATED;
switch (what->aux & EAF_TYPE_MASK) {
case EAF_TYPE_INT:
if (v1.type != T_INT)
runtime( "Setting int attribute to non-int value" );
l->attrs[0].u.data = v1.val.i;
break;
case EAF_TYPE_AS_PATH:
if (v1.type != T_PATH)
runtime( "Setting path attribute to non-path value" );
l->attrs[0].u.ptr = v1.val.ad;
break;
case EAF_TYPE_INT_SET:
if (v1.type != T_CLIST)
runtime( "Setting int set attribute to non-clist value" );
l->attrs[0].u.ptr = v1.val.ad;
break;
case EAF_TYPE_UNDEF:
if (v1.type != T_VOID)
runtime( "Setting void attribute to non-void value" );
l->attrs[0].u.data = 0;
break;
default: bug("Unknown type in e,S");
}
if (!(what->aux & EAF_TEMP) && (!(f_flags & FF_FORCE_TMPATTR))) {
if (!f_rta_copy) {
f_rta_copy = lp_alloc(f_pool, sizeof(rta));
memcpy(f_rta_copy, (*f_rte)->attrs, sizeof(rta));
f_rta_copy->aflags = 0;
*f_rte = rte_cow(*f_rte);
(*f_rte)->attrs = f_rta_copy;
}
l->next = f_rta_copy->eattrs;
f_rta_copy->eattrs = l;
} else {
l->next = (*f_tmp_attrs);
(*f_tmp_attrs) = l;
}
}
break;
case 'L': /* Get length of */
ONEARG;
res.type = T_INT;
switch(v1.type) {
case T_PREFIX: res.val.i = v1.val.px.len; break;
case T_PATH: res.val.i = as_path_getlen(v1.val.ad); break;
default: bug( "Length of what?" );
}
break;
case P('c','p'): /* Convert prefix to ... */
ONEARG;
if (v1.type != T_PREFIX)
runtime( "Can not convert non-prefix this way" );
res.type = what->aux;
switch(res.type) {
/* case T_INT: res.val.i = v1.val.px.len; break; Not needed any more */
case T_IP: res.val.px.ip = v1.val.px.ip; break;
default: bug( "Unknown prefix to conversion" );
}
break;
case 'r':
ONEARG;
res = v1;
res.type |= T_RETURN;
break;
case P('c','a'): /* CALL: this is special: if T_RETURN and returning some value, mask it out */
ONEARG;
res = interpret(what->a2.p);
if (res.type == T_RETURN)
return res;
res.type &= ~T_RETURN;
break;
case P('S','W'):
ONEARG;
{
struct f_tree *t = find_tree(what->a2.p, v1);
if (!t) {
v1.type = T_VOID;
t = find_tree(what->a2.p, v1);
if (!t) {
debug( "No else statement?\n ");
break;
}
}
if (!t->data)
bug( "Impossible: no code associated!" );
return interpret(t->data);
}
break;
case P('i','M'): /* IP.MASK(val) */
TWOARGS;
if (v2.type != T_INT)
runtime( "Can not use this type for mask.");
if (v1.type != T_IP)
runtime( "You can mask only IP addresses." );
{
ip_addr mask = ipa_mkmask(v2.val.i);
res.type = T_IP;
res.val.px.ip = ipa_and(mask, v1.val.px.ip);
}
break;
case 'E': /* Create empty attribute */
res.type = what->aux;
res.val.ad = adata_empty(f_pool);
break;
case P('A','p'): /* Path prepend */
TWOARGS;
if (v1.type != T_PATH)
runtime("Can't prepend to non-path");
if (v2.type != T_INT)
runtime("Can't prepend non-integer");
res.type = T_PATH;
res.val.ad = as_path_prepend(f_pool, v1.val.ad, v2.val.i);
break;
case P('C','a'): /* Community list add or delete */
TWOARGS;
if (v1.type != T_CLIST)
runtime("Can't add/delete to non-clist");
if (v2.type != T_PAIR)
runtime("Can't add/delete non-pair");
res.type = T_CLIST;
switch (what->aux) {
case 'a': res.val.ad = int_set_add(f_pool, v1.val.ad, v2.val.i); break;
case 'd': res.val.ad = int_set_del(f_pool, v1.val.ad, v2.val.i); break;
default: bug("unknown Ca operation");
}
break;
default:
bug( "Unknown instruction %d (%c)", what->code, what->code & 0xff);
}
if (what->next)
return interpret(what->next);
return res;
}
#undef ARG
#define ARG(x,y) \
if (!i_same(f1->y, f2->y)) \
return 0;
#define ONEARG ARG(v1, a1.p)
#define TWOARGS ARG(v1, a1.p) \
ARG(v2, a2.p)
#define A2_SAME if (f1->a2.i != f2->a2.i) return 0;
int
i_same(struct f_inst *f1, struct f_inst *f2)
{
if ((!!f1) != (!!f2))
return 0;
if (!f1)
return 1;
if (f1->aux != f2->aux)
return 0;
if (f1->code != f2->code)
return 0;
if (f1 == f2) /* It looks strange, but it is possible with call rewriting trickery */
return 1;
switch(f1->code) {
case ',': /* fall through */
case '+':
case '-':
case '*':
case '/':
case P('!','='):
case P('=','='):
case '<':
case P('<','='): TWOARGS; break;
case '!': ONEARG; break;
case '~': TWOARGS; break;
case P('d','e'): ONEARG; break;
case 's':
ARG(v2, a2.p);
{
struct symbol *s1, *s2;
s1 = f1->a1.p;
s2 = f2->a1.p;
if (strcmp(s1->name, s2->name))
return 0;
if (s1->class != s2->class)
return 0;
}
break;
case 'c': A2_SAME; break;
case 'C':
if (val_compare(* (struct f_val *) f1->a1.p, * (struct f_val *) f2->a1.p))
return 0;
break;
case 'p': case 'L': ONEARG; break;
case '?': TWOARGS; break;
case '0': case 'E': break;
case P('p',','): ONEARG; A2_SAME; break;
case 'a': A2_SAME; break;
case P('e','a'): A2_SAME; break;
case P('e','S'): ONEARG; A2_SAME; break;
case 'r': ONEARG; break;
case P('c','p'): ONEARG; break;
case P('c','a'): /* Call rewriting trickery to avoid exponential behaviour */
ONEARG;
if (!i_same(f1->a2.p, f2->a2.p))
return 0;
f2->a2.p = f1->a2.p;
break;
case P('S','W'): ONEARG; if (!same_tree(f1->a2.p, f2->a2.p)) return 0; break;
case P('i','M'): TWOARGS; break;
case P('A','p'): TWOARGS; break;
case P('C','a'): TWOARGS; break;
default:
bug( "Unknown instruction %d in same (%c)", f1->code, f1->code & 0xff);
}
return i_same(f1->next, f2->next);
}
/**
* f_run - external entry point to filters
* @filter: pointer to filter to run
* @rte: pointer to pointer to rte being filtered. When route is modified, this is changed with rte_cow.
* @tmp_pool: all filter allocations go from this pool
*/
int
f_run(struct filter *filter, struct rte **rte, struct ea_list **tmp_attrs, struct linpool *tmp_pool, int flags)
{
struct f_inst *inst;
struct f_val res;
DBG( "Running filter `%s'...", filter->name );
f_flags = flags;
f_tmp_attrs = tmp_attrs;
f_rte = rte;
f_rte_old = *rte;
f_rta_copy = NULL;
f_pool = tmp_pool;
inst = filter->root;
res = interpret(inst);
if (res.type != T_RETURN)
return F_ERROR;
DBG( "done (%d)\n", res.val.i );
return res.val.i;
}
int
f_eval_int(struct f_inst *expr)
{
struct f_val res;
f_flags = 0;
f_tmp_attrs = NULL;
f_rte = NULL;
f_rte_old = NULL;
f_rta_copy = NULL;
f_pool = cfg_mem;
res = interpret(expr);
if (res.type != T_INT)
cf_error("Integer expression expected");
return res.val.i;
}
/**
* filter_same - compare two filters
* @new: first filter to be compared
* @old: second filter to be compared, notice that this filter is
* damaged while comparing.
*
* Returns 1 in case filters are same, otherwise 0. If there are
* underlying bugs, it will rather say 0 on same filters than say
* 1 on different.
*/
int
filter_same(struct filter *new, struct filter *old)
{
if (old == new) /* Handle FILTER_ACCEPT and FILTER_REJECT */
return 1;
if (old == FILTER_ACCEPT || old == FILTER_REJECT ||
new == FILTER_ACCEPT || new == FILTER_REJECT)
return 0;
return i_same(new->root, old->root);
}
struct adata *
adata_empty(struct linpool *pool)
{
struct adata *res = lp_alloc(pool, sizeof(struct adata));
res->length = 0;
return res;
}
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