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If we hit a cache internal error, log the entry we failed to remove.

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This is code which should never run, but if it does,
we now log information useful for debugging.
This commit is contained in:
Simon Kelley
2022-12-22 23:19:05 +00:00
parent e6841ea2e0
commit 43a2a66531
1 changed files with 97 additions and 82 deletions
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179
src/cache.c
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@@ -28,6 +28,7 @@ static int bignames_left, hash_size;
static void make_non_terminals(struct crec *source);
static struct crec *really_insert(char *name, union all_addr *addr, unsigned short class,
time_t now, unsigned long ttl, unsigned int flags);
static void dump_cache_entry(struct crec *cache, time_t now);
/* type->string mapping: this is also used by the name-hash function as a mixing table. */
/* taken from https://www.iana.org/assignments/dns-parameters/dns-parameters.xhtml */
@@ -594,7 +595,7 @@ static struct crec *really_insert(char *name, union all_addr *addr, unsigned sho
struct crec *new, *target_crec = NULL;
union bigname *big_name = NULL;
int freed_all = (flags & F_REVERSE);
int free_avail = 0;
struct crec *free_avail = NULL;
unsigned int target_uid;
/* if previous insertion failed give up now. */
@@ -642,7 +643,7 @@ static struct crec *really_insert(char *name, union all_addr *addr, unsigned sho
/* Free entry at end of LRU list, use it. */
if (!(new->flags & (F_FORWARD | F_REVERSE)))
break;
break;
/* End of LRU list is still in use: if we didn't scan all the hash
chains for expired entries do that now. If we already tried that
@@ -658,6 +659,8 @@ static struct crec *really_insert(char *name, union all_addr *addr, unsigned sho
if (!warned)
{
my_syslog(LOG_ERR, _("Internal error in cache."));
/* Log the entry we tried to delete. */
dump_cache_entry(free_avail, now);
warned = 1;
}
insert_error = 1;
@@ -667,13 +670,13 @@ static struct crec *really_insert(char *name, union all_addr *addr, unsigned sho
if (freed_all)
{
/* For DNSSEC records, uid holds class. */
free_avail = 1; /* Must be free space now. */
free_avail = new; /* Must be free space now. */
/* condition valid when stale-caching */
if (difftime(now, new->ttd) < 0)
daemon->metrics[METRIC_DNS_CACHE_LIVE_FREED]++;
cache_scan_free(cache_get_name(new), &new->addr, new->uid, now, new->flags, NULL, NULL);
cache_scan_free(cache_get_name(new), &new->addr, new->uid, now, new->flags, NULL, NULL);
}
else
{
@@ -1760,6 +1763,94 @@ static char *sanitise(char *name)
return name;
}
static void dump_cache_entry(struct crec *cache, time_t now)
{
(void)now;
static char *buff = NULL;
char *p, *t = " ";
char *a = daemon->addrbuff, *n = cache_get_name(cache);
/* String length is limited below */
if (!buff && !(buff = whine_malloc(150)))
return;
p = buff;
*a = 0;
if (strlen(n) == 0 && !(cache->flags & F_REVERSE))
n = "<Root>";
p += sprintf(p, "%-30.30s ", sanitise(n));
if ((cache->flags & F_CNAME) && !is_outdated_cname_pointer(cache))
a = sanitise(cache_get_cname_target(cache));
else if ((cache->flags & F_SRV) && !(cache->flags & F_NEG))
{
int targetlen = cache->addr.srv.targetlen;
ssize_t len = sprintf(a, "%u %u %u ", cache->addr.srv.priority,
cache->addr.srv.weight, cache->addr.srv.srvport);
if (targetlen > (40 - len))
targetlen = 40 - len;
blockdata_retrieve(cache->addr.srv.target, targetlen, a + len);
a[len + targetlen] = 0;
}
#ifdef HAVE_DNSSEC
else if (cache->flags & F_DS)
{
if (!(cache->flags & F_NEG))
sprintf(a, "%5u %3u %3u", cache->addr.ds.keytag,
cache->addr.ds.algo, cache->addr.ds.digest);
}
else if (cache->flags & F_DNSKEY)
sprintf(a, "%5u %3u %3u", cache->addr.key.keytag,
cache->addr.key.algo, cache->addr.key.flags);
#endif
else if (!(cache->flags & F_NEG) || !(cache->flags & F_FORWARD))
{
a = daemon->addrbuff;
if (cache->flags & F_IPV4)
inet_ntop(AF_INET, &cache->addr, a, ADDRSTRLEN);
else if (cache->flags & F_IPV6)
inet_ntop(AF_INET6, &cache->addr, a, ADDRSTRLEN);
}
if (cache->flags & F_IPV4)
t = "4";
else if (cache->flags & F_IPV6)
t = "6";
else if (cache->flags & F_CNAME)
t = "C";
else if (cache->flags & F_SRV)
t = "V";
#ifdef HAVE_DNSSEC
else if (cache->flags & F_DS)
t = "S";
else if (cache->flags & F_DNSKEY)
t = "K";
#endif
else /* non-terminal */
t = "!";
p += sprintf(p, "%-40.40s %s%s%s%s%s%s%s%s%s%s ", a, t,
cache->flags & F_FORWARD ? "F" : " ",
cache->flags & F_REVERSE ? "R" : " ",
cache->flags & F_IMMORTAL ? "I" : " ",
cache->flags & F_DHCP ? "D" : " ",
cache->flags & F_NEG ? "N" : " ",
cache->flags & F_NXDOMAIN ? "X" : " ",
cache->flags & F_HOSTS ? "H" : " ",
cache->flags & F_CONFIG ? "C" : " ",
cache->flags & F_DNSSECOK ? "V" : " ");
#ifdef HAVE_BROKEN_RTC
p += sprintf(p, "%-24lu", cache->flags & F_IMMORTAL ? 0: (unsigned long)(cache->ttd - now));
#else
p += sprintf(p, "%-24.24s", cache->flags & F_IMMORTAL ? "" : ctime(&(cache->ttd)));
#endif
if(cache->flags & (F_HOSTS | F_CONFIG) && cache->uid > 0)
p += sprintf(p, " %-40.40s", record_source(cache->uid));
my_syslog(LOG_INFO, "%s", buff);
}
void dump_cache(time_t now)
{
@@ -1807,90 +1898,14 @@ void dump_cache(time_t now)
if (option_bool(OPT_DEBUG) || option_bool(OPT_LOG))
{
struct crec *cache ;
struct crec *cache;
int i;
my_syslog(LOG_INFO, "Host Address Flags Expires Source");
my_syslog(LOG_INFO, "------------------------------ ---------------------------------------- ---------- ------------------------ ------------");
for (i=0; i<hash_size; i++)
for (cache = hash_table[i]; cache; cache = cache->hash_next)
{
char *t = " ";
char *a = daemon->addrbuff, *p = daemon->namebuff, *n = cache_get_name(cache);
*a = 0;
if (strlen(n) == 0 && !(cache->flags & F_REVERSE))
n = "<Root>";
p += sprintf(p, "%-30.30s ", sanitise(n));
if ((cache->flags & F_CNAME) && !is_outdated_cname_pointer(cache))
a = sanitise(cache_get_cname_target(cache));
else if ((cache->flags & F_SRV) && !(cache->flags & F_NEG))
{
int targetlen = cache->addr.srv.targetlen;
ssize_t len = sprintf(a, "%u %u %u ", cache->addr.srv.priority,
cache->addr.srv.weight, cache->addr.srv.srvport);
if (targetlen > (40 - len))
targetlen = 40 - len;
blockdata_retrieve(cache->addr.srv.target, targetlen, a + len);
a[len + targetlen] = 0;
}
#ifdef HAVE_DNSSEC
else if (cache->flags & F_DS)
{
if (!(cache->flags & F_NEG))
sprintf(a, "%5u %3u %3u", cache->addr.ds.keytag,
cache->addr.ds.algo, cache->addr.ds.digest);
}
else if (cache->flags & F_DNSKEY)
sprintf(a, "%5u %3u %3u", cache->addr.key.keytag,
cache->addr.key.algo, cache->addr.key.flags);
#endif
else if (!(cache->flags & F_NEG) || !(cache->flags & F_FORWARD))
{
a = daemon->addrbuff;
if (cache->flags & F_IPV4)
inet_ntop(AF_INET, &cache->addr, a, ADDRSTRLEN);
else if (cache->flags & F_IPV6)
inet_ntop(AF_INET6, &cache->addr, a, ADDRSTRLEN);
}
if (cache->flags & F_IPV4)
t = "4";
else if (cache->flags & F_IPV6)
t = "6";
else if (cache->flags & F_CNAME)
t = "C";
else if (cache->flags & F_SRV)
t = "V";
#ifdef HAVE_DNSSEC
else if (cache->flags & F_DS)
t = "S";
else if (cache->flags & F_DNSKEY)
t = "K";
#endif
else /* non-terminal */
t = "!";
p += sprintf(p, "%-40.40s %s%s%s%s%s%s%s%s%s%s ", a, t,
cache->flags & F_FORWARD ? "F" : " ",
cache->flags & F_REVERSE ? "R" : " ",
cache->flags & F_IMMORTAL ? "I" : " ",
cache->flags & F_DHCP ? "D" : " ",
cache->flags & F_NEG ? "N" : " ",
cache->flags & F_NXDOMAIN ? "X" : " ",
cache->flags & F_HOSTS ? "H" : " ",
cache->flags & F_CONFIG ? "C" : " ",
cache->flags & F_DNSSECOK ? "V" : " ");
#ifdef HAVE_BROKEN_RTC
p += sprintf(p, "%-24lu", cache->flags & F_IMMORTAL ? 0: (unsigned long)(cache->ttd - now));
#else
p += sprintf(p, "%-24.24s", cache->flags & F_IMMORTAL ? "" : ctime(&(cache->ttd)));
#endif
if(cache->flags & (F_HOSTS | F_CONFIG) && cache->uid > 0)
p += sprintf(p, " %s", record_source(cache->uid));
my_syslog(LOG_INFO, "%s", daemon->namebuff);
}
dump_cache_entry(cache, now);
}
}