resolved: for a transaction, keep track where the answer data came from

Let's track where the data came from: from the network, the cache or the
local zone. This is not only useful for debugging purposes, but is also
useful when the zone probing wants to ensure it's not reusing
transactions that were answered from the cache or the zone itself.

1 files changed, 14 insertions, 1 deletions

diff --git a/src/resolve/resolved-dns-transaction.h b/src/resolve/resolved-dns-transaction.h
index a56bcdb6d6..ee80dcf5a9 100644
--- a/src/resolve/resolved-dns-transaction.h
+++ b/src/resolve/resolved-dns-transaction.h
@@ -23,6 +23,7 @@
 
 typedef struct DnsTransaction DnsTransaction;
 typedef enum DnsTransactionState DnsTransactionState;
+typedef enum DnsTransactionSource DnsTransactionSource;
 
 enum DnsTransactionState {
         DNS_TRANSACTION_NULL,
@@ -39,6 +40,14 @@ enum DnsTransactionState {
         _DNS_TRANSACTION_STATE_INVALID = -1
 };
 
+enum DnsTransactionSource {
+        DNS_TRANSACTION_NETWORK,
+        DNS_TRANSACTION_CACHE,
+        DNS_TRANSACTION_ZONE,
+        _DNS_TRANSACTION_SOURCE_MAX,
+        _DNS_TRANSACTION_SOURCE_INVALID = -1
+};
+
 #include "resolved-dns-answer.h"
 #include "resolved-dns-packet.h"
 #include "resolved-dns-question.h"
@@ -58,6 +67,7 @@ struct DnsTransaction {
 
         DnsAnswer *answer;
         int answer_rcode;
+        DnsTransactionSource answer_source;
 
         usec_t start_usec;
         sd_event_source *timeout_event_source;
@@ -98,6 +108,9 @@ void dns_transaction_complete(DnsTransaction *t, DnsTransactionState state);
 const char* dns_transaction_state_to_string(DnsTransactionState p) _const_;
 DnsTransactionState dns_transaction_state_from_string(const char *s) _pure_;
 
+const char* dns_transaction_source_to_string(DnsTransactionSource p) _const_;
+DnsTransactionSource dns_transaction_source_from_string(const char *s) _pure_;
+
 /* LLMNR Jitter interval, see RFC 4795 Section 7 */
 #define LLMNR_JITTER_INTERVAL_USEC (100 * USEC_PER_MSEC)
 
@@ -107,4 +120,4 @@ DnsTransactionState dns_transaction_state_from_string(const char *s) _pure_;
 /* Maximum attempts to send LLMNR requests, see RFC 4795 Section 2.7 */
 #define LLMNR_TRANSACTION_ATTEMPTS_MAX 3
 
-#define TRANSACTION_ATTEMPTS_MAX(p) (p == DNS_PROTOCOL_LLMNR ? LLMNR_TRANSACTION_ATTEMPTS_MAX : DNS_TRANSACTION_ATTEMPTS_MAX)
+#define TRANSACTION_ATTEMPTS_MAX(p) ((p) == DNS_PROTOCOL_LLMNR ? LLMNR_TRANSACTION_ATTEMPTS_MAX : DNS_TRANSACTION_ATTEMPTS_MAX)