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LookupServer: Cache DNS answers for TTL seconds

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We now keep DNS answers around in a cache for TTL seconds after getting
them the first time. The cache is capped at 256 responses for now.

Suggested by @zecke in #10.
This commit is contained in:
Andreas Kling 2020-01-26 15:42:03 +01:00
parent 90a5907b44
commit 5e47508672
5 changed files with 71 additions and 17 deletions
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22
Servers/LookupServer/LookupServer.cpp
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@ -157,8 +157,16 @@ Vector<String> LookupServer::lookup(const String& hostname, bool& did_timeout, u
{
if (auto it = m_lookup_cache.find(hostname); it != m_lookup_cache.end()) {
auto& cached_lookup = it->value;
if (cached_lookup.record_type == record_type && cached_lookup.timestamp < (time(nullptr) + 60)) {
return it->value.responses;
if (cached_lookup.question.record_type() == record_type) {
Vector<String> responses;
for (auto& cached_answer : cached_lookup.answers) {
dbg() << "Cache hit: " << hostname << " -> " << cached_answer.record_data() << ", expired: " << cached_answer.has_expired();
if (!cached_answer.has_expired()) {
responses.append(cached_answer.record_data());
}
}
if (!responses.is_empty())
return responses;
}
m_lookup_cache.remove(it);
}
@ -232,11 +240,13 @@ Vector<String> LookupServer::lookup(const String& hostname, bool& did_timeout, u
return {};
}
Vector<String> addresses;
Vector<String> responses;
for (auto& answer : response.answers()) {
addresses.append(answer.record_data());
responses.append(answer.record_data());
}
m_lookup_cache.set(hostname, { time(nullptr), record_type, addresses });
return addresses;
if (m_lookup_cache.size() >= 256)
m_lookup_cache.remove(m_lookup_cache.begin());
m_lookup_cache.set(hostname, { request.questions()[0], response.answers() });
return responses;
}