Use provided buffer in dns_resource_key_to_string

When the buffer is allocated on the stack we do not have to check for
failure everywhere. This is especially useful in debug statements, because
we can put dns_resource_key_to_string() call in the debug statement, and
we do not need a seperate if (log_level >= LOG_DEBUG) for the conversion.

dns_resource_key_to_string() is changed not to provide any whitespace
padding. Most callers were stripping the whitespace with strstrip(),
and it did not look to well anyway. systemd-resolve output is not column
aligned anymore.

The result of the conversion is not stored in DnsTransaction object
anymore. It is used only for debugging, so it seems fine to generate it
when needed.

Various debug statements are extended to provide more information.

1 files changed, 50 insertions, 88 deletions

diff --git a/src/resolve/resolved-dns-cache.c b/src/resolve/resolved-dns-cache.c
index b8e4bd3dd2..4b7672fbbf 100644
--- a/src/resolve/resolved-dns-cache.c
+++ b/src/resolve/resolved-dns-cache.c
@@ -17,6 +17,9 @@
   along with systemd; If not, see <http://www.gnu.org/licenses/>.
 ***/
 
+#include <net/if.h>
+
+#include "af-list.h"
 #include "alloc-util.h"
 #include "dns-domain.h"
 #include "resolved-dns-answer.h"
@@ -180,6 +183,7 @@ void dns_cache_prune(DnsCache *c) {
 
         for (;;) {
                 DnsCacheItem *i;
+                char key_str[DNS_RESOURCE_KEY_STRING_MAX];
 
                 i = prioq_peek(c->by_expiry);
                 if (!i)
@@ -192,8 +196,12 @@ void dns_cache_prune(DnsCache *c) {
                         break;
 
                 /* Depending whether this is an mDNS shared entry
-                 * either remove only this one RR or the whole
-                 * RRset */
+                 * either remove only this one RR or the whole RRset */
+                log_debug("Removing %scache entry for %s (expired "USEC_FMT"s ago)",
+                          i->shared_owner ? "shared " : "",
+                          dns_resource_key_to_string(i->key, key_str, sizeof key_str),
+                          (t - i->until) / USEC_PER_SEC);
+
                 if (i->shared_owner)
                         dns_cache_item_unlink_and_free(c, i);
                 else {
@@ -375,8 +383,8 @@ static int dns_cache_put_positive(
                 const union in_addr_union *owner_address) {
 
         _cleanup_(dns_cache_item_freep) DnsCacheItem *i = NULL;
-        _cleanup_free_ char *key_str = NULL;
         DnsCacheItem *existing;
+        char key_str[DNS_RESOURCE_KEY_STRING_MAX], ifname[IF_NAMESIZE];
         int r, k;
 
         assert(c);
@@ -392,18 +400,9 @@ static int dns_cache_put_positive(
         /* New TTL is 0? Delete this specific entry... */
         if (rr->ttl <= 0) {
                 k = dns_cache_remove_by_rr(c, rr);
-
-                if (log_get_max_level() >= LOG_DEBUG) {
-                        r = dns_resource_key_to_string(rr->key, &key_str);
-                        if (r < 0)
-                                return r;
-
-                        if (k > 0)
-                                log_debug("Removed zero TTL entry from cache: %s", key_str);
-                        else
-                                log_debug("Not caching zero TTL cache entry: %s", key_str);
-                }
-
+                log_debug("%s: %s",
+                          k > 0 ? "Removed zero TTL entry from cache" : "Not caching zero TTL cache entry",
+                          dns_resource_key_to_string(i->key, key_str, sizeof key_str));
                 return 0;
         }
 
@@ -450,11 +449,18 @@ static int dns_cache_put_positive(
                 return r;
 
         if (log_get_max_level() >= LOG_DEBUG) {
-                r = dns_resource_key_to_string(i->key, &key_str);
-                if (r < 0)
-                        return r;
-
-                log_debug("Added positive cache entry for %s", key_str);
+                _cleanup_free_ char *t = NULL;
+
+                (void) in_addr_to_string(i->owner_family, &i->owner_address, &t);
+
+                log_debug("Added positive %s%s cache entry for %s "USEC_FMT"s on %s/%s/%s",
+                          i->authenticated ? "authenticated" : "unauthenticated",
+                          i->shared_owner ? " shared" : "",
+                          dns_resource_key_to_string(i->key, key_str, sizeof key_str),
+                          (i->until - timestamp) / USEC_PER_SEC,
+                          i->ifindex == 0 ? "*" : strna(if_indextoname(i->ifindex, ifname)),
+                          af_to_name_short(i->owner_family),
+                          strna(t));
         }
 
         i = NULL;
@@ -473,7 +479,7 @@ static int dns_cache_put_negative(
                 const union in_addr_union *owner_address) {
 
         _cleanup_(dns_cache_item_freep) DnsCacheItem *i = NULL;
-        _cleanup_free_ char *key_str = NULL;
+        char key_str[DNS_RESOURCE_KEY_STRING_MAX];
         int r;
 
         assert(c);
@@ -490,14 +496,8 @@ static int dns_cache_put_negative(
                 return 0;
 
         if (nsec_ttl <= 0 || soa->soa.minimum <= 0 || soa->ttl <= 0) {
-                if (log_get_max_level() >= LOG_DEBUG) {
-                        r = dns_resource_key_to_string(key, &key_str);
-                        if (r < 0)
-                                return r;
-
-                        log_debug("Not caching negative entry with zero SOA/NSEC/NSEC3 TTL: %s", key_str);
-                }
-
+                log_debug("Not caching negative entry with zero SOA/NSEC/NSEC3 TTL: %s",
+                          dns_resource_key_to_string(i->key, key_str, sizeof key_str));
                 return 0;
         }
 
@@ -542,13 +542,10 @@ static int dns_cache_put_negative(
         if (r < 0)
                 return r;
 
-        if (log_get_max_level() >= LOG_DEBUG) {
-                r = dns_resource_key_to_string(i->key, &key_str);
-                if (r < 0)
-                        return r;
-
-                log_debug("Added %s cache entry for %s", i->type == DNS_CACHE_NODATA ? "NODATA" : "NXDOMAIN", key_str);
-        }
+        log_debug("Added %s cache entry for %s "USEC_FMT"s",
+                  i->type == DNS_CACHE_NODATA ? "NODATA" : "NXDOMAIN",
+                  dns_resource_key_to_string(i->key, key_str, sizeof key_str),
+                  (i->until - timestamp) / USEC_PER_SEC);
 
         i = NULL;
         return 0;
@@ -628,16 +625,10 @@ int dns_cache_put(
         dns_cache_remove_previous(c, key, answer);
 
         if (dns_answer_size(answer) <= 0) {
-                if (log_get_max_level() >= LOG_DEBUG) {
-                        _cleanup_free_ char *key_str = NULL;
-
-                        r = dns_resource_key_to_string(key, &key_str);
-                        if (r < 0)
-                                return r;
-
-                        log_debug("Not caching negative entry without a SOA record: %s", key_str);
-                }
+                char key_str[DNS_RESOURCE_KEY_STRING_MAX];
 
+                log_debug("Not caching negative entry without a SOA record: %s",
+                          dns_resource_key_to_string(key, key_str, sizeof key_str));
                 return 0;
         }
 
@@ -801,10 +792,10 @@ static DnsCacheItem *dns_cache_get_by_key_follow_cname_dname_nsec(DnsCache *c, D
 
 int dns_cache_lookup(DnsCache *c, DnsResourceKey *key, int *rcode, DnsAnswer **ret, bool *authenticated) {
         _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL;
+        char key_str[DNS_RESOURCE_KEY_STRING_MAX];
         unsigned n = 0;
         int r;
         bool nxdomain = false;
-        _cleanup_free_ char *key_str = NULL;
         DnsCacheItem *j, *first, *nsec = NULL;
         bool have_authenticated = false, have_non_authenticated = false;
 
@@ -814,19 +805,12 @@ int dns_cache_lookup(DnsCache *c, DnsResourceKey *key, int *rcode, DnsAnswer **r
         assert(ret);
         assert(authenticated);
 
-        if (key->type == DNS_TYPE_ANY ||
-            key->class == DNS_CLASS_ANY) {
-
+        if (key->type == DNS_TYPE_ANY || key->class == DNS_CLASS_ANY) {
                 /* If we have ANY lookups we don't use the cache, so
                  * that the caller refreshes via the network. */
 
-                if (log_get_max_level() >= LOG_DEBUG) {
-                        r = dns_resource_key_to_string(key, &key_str);
-                        if (r < 0)
-                                return r;
-
-                        log_debug("Ignoring cache for ANY lookup: %s", key_str);
-                }
+                log_debug("Ignoring cache for ANY lookup: %s",
+                          dns_resource_key_to_string(key, key_str, sizeof key_str));
 
                 c->n_miss++;
 
@@ -839,13 +823,8 @@ int dns_cache_lookup(DnsCache *c, DnsResourceKey *key, int *rcode, DnsAnswer **r
         if (!first) {
                 /* If one question cannot be answered we need to refresh */
 
-                if (log_get_max_level() >= LOG_DEBUG) {
-                        r = dns_resource_key_to_string(key, &key_str);
-                        if (r < 0)
-                                return r;
-
-                        log_debug("Cache miss for %s", key_str);
-                }
+                log_debug("Cache miss for %s",
+                          dns_resource_key_to_string(key, key_str, sizeof key_str));
 
                 c->n_miss++;
 
@@ -873,13 +852,8 @@ int dns_cache_lookup(DnsCache *c, DnsResourceKey *key, int *rcode, DnsAnswer **r
                 /* Note that we won't derive information for DS RRs from an NSEC, because we only cache NSEC RRs from
                  * the lower-zone of a zone cut, but the DS RRs are on the upper zone. */
 
-                if (log_get_max_level() >= LOG_DEBUG) {
-                        r = dns_resource_key_to_string(key, &key_str);
-                        if (r < 0)
-                                return r;
-
-                        log_debug("NSEC NODATA cache hit for %s", key_str);
-                }
+                log_debug("NSEC NODATA cache hit for %s",
+                          dns_resource_key_to_string(key, key_str, sizeof key_str));
 
                 /* We only found an NSEC record that matches our name.
                  * If it says the type doesn't exist report
@@ -900,16 +874,10 @@ int dns_cache_lookup(DnsCache *c, DnsResourceKey *key, int *rcode, DnsAnswer **r
                 return 0;
         }
 
-        if (log_get_max_level() >= LOG_DEBUG) {
-                r = dns_resource_key_to_string(key, &key_str);
-                if (r < 0)
-                        return r;
-
-                log_debug("%s cache hit for %s",
-                          n > 0    ? "Positive" :
-                          nxdomain ? "NXDOMAIN" : "NODATA",
-                          key_str);
-        }
+        log_debug("%s cache hit for %s",
+                  n > 0    ? "Positive" :
+                  nxdomain ? "NXDOMAIN" : "NODATA",
+                  dns_resource_key_to_string(key, key_str, sizeof key_str));
 
         if (n <= 0) {
                 c->n_hit++;
@@ -1031,7 +999,6 @@ int dns_cache_export_shared_to_packet(DnsCache *cache, DnsPacket *p) {
 void dns_cache_dump(DnsCache *cache, FILE *f) {
         Iterator iterator;
         DnsCacheItem *i;
-        int r;
 
         if (!cache)
                 return;
@@ -1057,14 +1024,9 @@ void dns_cache_dump(DnsCache *cache, FILE *f) {
                                 fputs(t, f);
                                 fputc('\n', f);
                         } else {
-                                _cleanup_free_ char *z = NULL;
-                                r = dns_resource_key_to_string(j->key, &z);
-                                if (r < 0) {
-                                        log_oom();
-                                        continue;
-                                }
+                                char key_str[DNS_RESOURCE_KEY_STRING_MAX];
 
-                                fputs(z, f);
+                                fputs(dns_resource_key_to_string(j->key, key_str, sizeof key_str), f);
                                 fputs(" -- ", f);
                                 fputs(j->type == DNS_CACHE_NODATA ? "NODATA" : "NXDOMAIN", f);
                                 fputc('\n', f);