/**
* trie_match
* @t: trie
* @px: prefix address
* @plen: prefix length
*
* Tries to find a matching prefix pattern in the trie such that
* prefix @px/@plen matches that prefix pattern. Returns 1 if there
* is such prefix pattern in the trie.
*/
int
trie_match_prefix(struct f_trie *t, ip_addr px, int plen)
{
ip_addr pmask = ipa_mkmask(plen);
ip_addr paddr = ipa_and(px, pmask);
if (plen == 0)
return t->zero;
int plentest = plen - 1;
struct f_trie_node *n = &t->root;
while(n)
{
ip_addr cmask = ipa_and(n->mask, pmask);
/* We are out of path */
if (ipa_compare(ipa_and(paddr, cmask), ipa_and(n->addr, cmask)))
return 0;
/* Check accept mask */
if (ipa_getbit(n->accept, plentest))
return 1;
/* We finished trie walk and still no match */
if (plen <= n->plen)
return 0;
/* Choose children */
n = n->c[(ipa_getbit(paddr, n->plen)) ? 1 : 0];
}
return 0;
}
/* Compare nexthops during merge.
We need to maintain nhs sorted to eliminate duplicities */
static int
cmp_nhs(struct mpnh *s1, struct mpnh *s2)
{
int r;
if (!s1)
return 1;
if (!s2)
return -1;
r = ((int) s2->weight) - ((int) s1->weight);
if (r)
return r;
r = ipa_compare(s1->gw, s2->gw);
if (r)
return r;
return ((int) s1->iface->index) - ((int) s2->iface->index);
}
void
trie_add_prefix(struct f_trie *t, ip_addr px, int plen, int l, int h)
{
if (l == 0)
t->zero = 1;
else
l--;
if (h < plen)
plen = h;
ip_addr amask = ipa_xor(ipa_mkmask(l), ipa_mkmask(h));
ip_addr pmask = ipa_mkmask(plen);
ip_addr paddr = ipa_and(px, pmask);
struct f_trie_node *o = NULL;
struct f_trie_node *n = &t->root;
while(n)
{
ip_addr cmask = ipa_and(n->mask, pmask);
if (ipa_compare(ipa_and(paddr, cmask), ipa_and(n->addr, cmask)))
{
/* We are out of path - we have to add branching node 'b'
between node 'o' and node 'n', and attach new node 'a'
as the other child of 'b'. */
int blen = ipa_pxlen(paddr, n->addr);
ip_addr bmask = ipa_mkmask(blen);
ip_addr baddr = ipa_and(px, bmask);
/* Merge accept masks from children to get accept mask for node 'b' */
ip_addr baccm = ipa_and(ipa_or(amask, n->accept), bmask);
struct f_trie_node *a = new_node(t, plen, paddr, pmask, amask);
struct f_trie_node *b = new_node(t, blen, baddr, bmask, baccm);
attach_node(o, b);
attach_node(b, n);
attach_node(b, a);
return;
}
if (plen < n->plen)
{
/* We add new node 'a' between node 'o' and node 'n' */
amask = ipa_or(amask, ipa_and(n->accept, pmask));
struct f_trie_node *a = new_node(t, plen, paddr, pmask, amask);
attach_node(o, a);
attach_node(a, n);
return;
}
if (plen == n->plen)
{
/* We already found added node in trie. Just update accept mask */
n->accept = ipa_or(n->accept, amask);
return;
}
/* Update accept mask part M2 and go deeper */
n->accept = ipa_or(n->accept, ipa_and(amask, n->mask));
/* n->plen < plen and plen <= 32 (128) */
o = n;
n = n->c[ipa_getbit(paddr, n->plen) ? 1 : 0];
}
/* We add new tail node 'a' after node 'o' */
struct f_trie_node *a = new_node(t, plen, paddr, pmask, amask);
attach_node(o, a);
}
