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Speed up the execution of exit_policy_is_general_exit_helper()

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It isn't necessary to walk through all possible subnets when the policy
we're looking at doesn't touch that subnet.
This commit is contained in:
Sebastian Hahn
2010-02-05 16:58:24 +01:00
parent 01030a4db2
commit 1e49c908f7
1 changed files with 21 additions and 15 deletions
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src/or/policies.c
+21 -15
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@@ -870,7 +870,7 @@ policies_set_router_exitpolicy_to_reject_all(routerinfo_t *r)
static int
exit_policy_is_general_exit_helper(smartlist_t *policy, int port)
{
uint32_t j;
uint32_t mask, ip, i;
/* Is this /8 rejected (1), or undecided (0)? */
char subnet_status[256];
@@ -878,24 +878,30 @@ exit_policy_is_general_exit_helper(smartlist_t *policy, int port)
SMARTLIST_FOREACH(policy, addr_policy_t *, p, {
if (p->prt_min > port || p->prt_max < port)
continue; /* Doesn't cover our port. */
for (j = 0; j < 256; ++j) {
mask = 0;
tor_assert(p->maskbits <= 32);
if (p->maskbits)
mask = UINT32_MAX<<(32-p->maskbits);
ip = tor_addr_to_ipv4h(&p->addr);
/* Calculate the first and last subnet that this exit policy touches
* and set it as loop boundaries. */
for (i = ((mask & ip)>>24); i <= (~((mask & ip) ^ mask)>>24); ++i) {
tor_addr_t addr;
if (subnet_status[j] != 0)
if (subnet_status[i] != 0)
continue; /* We already reject some part of this /8 */
tor_addr_from_ipv4h(&addr, j<<24);
tor_addr_from_ipv4h(&addr, i<<24);
if (tor_addr_is_internal(&addr, 0))
continue; /* Local or non-routable addresses */
if (tor_addr_compare_masked(&addr, &p->addr, p->maskbits,
CMP_EXACT) == 0) {
if (p->policy_type == ADDR_POLICY_ACCEPT) {
if (p->maskbits > 8)
continue; /* Narrower than a /8. */
/* We found an allowed subnet of at least size /8. Done
* for this port! */
return 1;
} else if (p->policy_type == ADDR_POLICY_REJECT) {
subnet_status[j] = 1;
}
if (p->policy_type == ADDR_POLICY_ACCEPT) {
if (p->maskbits > 8)
continue; /* Narrower than a /8. */
/* We found an allowed subnet of at least size /8. Done
* for this port! */
return 1;
} else if (p->policy_type == ADDR_POLICY_REJECT) {
subnet_status[i] = 1;
}
}
});