LookupServer: Track the receive timestamp for DNS answers

Author: https://github.com/gunnarbeutner
Commit: edb21e02ea
Pull-request: https://github.com/SerenityOS/serenity/pull/6921
Reviewed-by: https://github.com/bugaevc

Userland/Services/LookupServer/DNSAnswer.cpp

@@ -18,15 +18,12 @@ DNSAnswer::DNSAnswer(const DNSName& name, DNSRecordType type, DNSRecordClass cla
     , m_record_data(record_data)
     , m_mdns_cache_flush(mdns_cache_flush)
 {
-    auto now = time(nullptr);
-    m_expiration_time = now + m_ttl;
-    if (m_expiration_time < now)
-        m_expiration_time = 0;
+    time(&m_received_time);
 }
 
 bool DNSAnswer::has_expired() const
 {
-    return time(nullptr) >= m_expiration_time;
+    return time(nullptr) >= m_received_time + m_ttl;
 }
 
 }

Userland/Services/LookupServer/DNSAnswer.h

@@ -40,6 +40,7 @@ public:
     DNSRecordClass class_code() const { return m_class_code; }
     u16 raw_class_code() const { return (u16)m_class_code | (m_mdns_cache_flush ? MDNS_CACHE_FLUSH : 0); }
     u32 ttl() const { return m_ttl; }
+    time_t received_time() const { return m_received_time; }
     const String& record_data() const { return m_record_data; }
     bool mdns_cache_flush() const { return m_mdns_cache_flush; }
 
@@ -50,7 +51,7 @@ private:
     DNSRecordType m_type { 0 };
     DNSRecordClass m_class_code { 0 };
     u32 m_ttl { 0 };
-    time_t m_expiration_time { 0 };
+    time_t m_received_time { 0 };
     String m_record_data;
     bool m_mdns_cache_flush { false };
 };