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Use an upper and lower bound for bridge weights

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When picking bridges (or other nodes without a consensus entry (and
thus no bandwidth weights)) we shouldn't just trust the node's
descriptor. So far we believed anything between 0 and 10MB/s, where 0
would mean that a node doesn't get any use from use unless it is our
only one, and 10MB/s would be a quite siginficant weight. To make this
situation better, we now believe weights in the range from 20kB/s to
100kB/s. This should allow new bridges to get use more quickly, and
means that it will be harder for bridges to see almost all our traffic.
This commit is contained in:
Sebastian Hahn
2010-09-30 06:10:56 +02:00
parent 45c51e3238
commit 73def430e3
1 changed files with 25 additions and 2 deletions
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src/or/routerlist.c
+25 -2
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@@ -1572,6 +1572,29 @@ router_get_advertised_bandwidth_capped(routerinfo_t *router)
return result;
}
/** When weighting bridges, enforce these values as lower and upper
* bound for believable bandwidth, because there is no way for us
* to verify a bridge's bandwidth currently. */
#define BRIDGE_MIN_BELIEVABLE_BANDWIDTH 20000 /* 20 kB/sec */
#define BRIDGE_MAX_BELIEVABLE_BANDWIDTH 100000 /* 100 kB/sec */
/** Return the smaller of the router's configured BandwidthRate
* and its advertised capacity, making sure to stay within the
* interval between bridge-min-believe-bw and
* bridge-max-believe-bw. */
static uint32_t
bridge_get_advertised_bandwidth_bounded(routerinfo_t *router)
{
uint32_t result = router->bandwidthcapacity;
if (result > router->bandwidthrate)
result = router->bandwidthrate;
if (result > BRIDGE_MAX_BELIEVABLE_BANDWIDTH)
result = BRIDGE_MAX_BELIEVABLE_BANDWIDTH;
else if (result < BRIDGE_MIN_BELIEVABLE_BANDWIDTH)
result = BRIDGE_MIN_BELIEVABLE_BANDWIDTH;
return result;
}
/** Return bw*1000, unless bw*1000 would overflow, in which case return
* INT32_MAX. */
static INLINE int32_t
@@ -1726,7 +1749,7 @@ smartlist_choose_by_bandwidth_weights(smartlist_t *sl,
if (rs && rs->has_bandwidth) {
this_bw = kb_to_bytes(rs->bandwidth);
} else { /* bridge or other descriptor not in our consensus */
this_bw = router_get_advertised_bandwidth_capped(router);
this_bw = bridge_get_advertised_bandwidth_bounded(router);
have_unknown = 1;
}
if (router_digest_is_me(router->cache_info.identity_digest))
@@ -1897,7 +1920,7 @@ smartlist_choose_by_bandwidth(smartlist_t *sl, bandwidth_weight_rule_t rule,
flags |= is_exit ? 2 : 0;
flags |= is_guard ? 4 : 0;
} else /* bridge or other descriptor not in our consensus */
this_bw = router_get_advertised_bandwidth_capped(router);
this_bw = bridge_get_advertised_bandwidth_bounded(router);
}
if (is_exit)
bitarray_set(exit_bits, i);