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geoip: Increment and decrement functions for the geoip client cache

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These functions protect againts over and underflow. They BUG() in case we
overflow the counter.

Signed-off-by: David Goulet <dgoulet@torproject.org>
This commit is contained in:
David Goulet 2018-02-02 13:14:50 -05:00
parent 51839f4765
commit 4d812e29b9
1 changed files with 30 additions and 2 deletions
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32
src/or/geoip.c
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@ -76,6 +76,34 @@ static char geoip6_digest[DIGEST_LEN];
* handler. */
static size_t geoip_client_history_cache_size;
/* Increment the geoip client history cache size counter with the given bytes.
* This prevents an overflow and set it to its maximum in that case. */
static inline void
geoip_increment_client_history_cache_size(size_t bytes)
{
/* This is shockingly high, lets log it so it can be reported. */
IF_BUG_ONCE(geoip_client_history_cache_size > (SIZE_MAX - bytes)) {
geoip_client_history_cache_size = SIZE_MAX;
return;
}
geoip_client_history_cache_size += bytes;
}
/* Decrement the geoip client history cache size counter with the given bytes.
* This prevents an underflow and set it to 0 in that case. */
static inline void
geoip_decrement_client_history_cache_size(size_t bytes)
{
/* Going below 0 means that we either allocated an entry without
* incrementing the counter or we have different sizes when allocating and
* freeing. It shouldn't happened so log it. */
IF_BUG_ONCE(geoip_client_history_cache_size < bytes) {
geoip_client_history_cache_size = 0;
return;
}
geoip_client_history_cache_size -= bytes;
}
/** Return the index of the <b>country</b>'s entry in the GeoIP
* country list if it is a valid 2-letter country code, otherwise
* return -1. */
@ -546,7 +574,7 @@ clientmap_entry_free(clientmap_entry_t *ent)
if (!ent)
return;
geoip_client_history_cache_size -= clientmap_entry_size(ent);
geoip_decrement_client_history_cache_size(clientmap_entry_size(ent));
tor_free(ent->transport_name);
tor_free(ent);
@ -610,7 +638,7 @@ geoip_note_client_seen(geoip_client_action_t action,
ent->transport_name = tor_strdup(transport_name);
ent->action = (int)action;
HT_INSERT(clientmap, &client_history, ent);
geoip_client_history_cache_size += clientmap_entry_size(ent);
geoip_increment_client_history_cache_size(clientmap_entry_size(ent));
}
if (now / 60 <= (int)MAX_LAST_SEEN_IN_MINUTES && now >= 0)
ent->last_seen_in_minutes = (unsigned)(now/60);