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LookupServer: Store /etc/hosts as Vector<DNSAnswer>

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...just like we store m_lookup_cache, in other words.

This immediately lets us match on types: for instance we will now only resolve
1.0.0.127.in-addr.arpa to localhost if asked for type PTR, not for type A. In
the future, this could also let us have the same /etc/hosts name resolve
to *multiple* addresses.
This commit is contained in:
Sergey Bugaev 2021-02-14 16:41:43 +03:00 • committed by Andreas Kling
parent e9387e43db
commit af6aac8c55
2 changed files with 26 additions and 6 deletions
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30
Userland/Services/LookupServer/LookupServer.cpp
View file

@ -79,6 +79,19 @@ LookupServer::LookupServer()
void LookupServer::load_etc_hosts()
{
// The TTL we return for static data from /etc/hosts.
// The value here is 1 day.
static constexpr u32 static_ttl = 86400;
auto add_answer = [this](const DNSName& name, unsigned short record_type, String data) {
auto it = m_etc_hosts.find(name);
if (it == m_etc_hosts.end()) {
m_etc_hosts.set(name, {});
it = m_etc_hosts.find(name);
}
it->value.empend(name, record_type, (u16)C_IN, static_ttl, data);
};
auto file = Core::File::construct("/etc/hosts");
if (!file->open(Core::IODevice::ReadOnly))
return;
@ -98,7 +111,7 @@ void LookupServer::load_etc_hosts()
auto raw_addr = addr.to_in_addr_t();
DNSName name = fields[1];
m_etc_hosts.set(name, String { (const char*)&raw_addr, sizeof(raw_addr) });
add_answer(name, T_A, String { (const char*)&raw_addr, sizeof(raw_addr) });
IPv4Address reverse_addr {
(u8)atoi(sections[3].characters()),
@ -109,7 +122,7 @@ void LookupServer::load_etc_hosts()
StringBuilder builder;
builder.append(reverse_addr.to_string());
builder.append(".in-addr.arpa");
m_etc_hosts.set(builder.to_string(), name);
add_answer(builder.to_string(), T_PTR, name.as_string());
}
}
@ -121,9 +134,16 @@ Vector<String> LookupServer::lookup(const DNSName& name, unsigned short record_t
Vector<String> responses;
if (auto known_host = m_etc_hosts.get(name); known_host.has_value()) {
responses.append(known_host.value());
} else if (!name.as_string().is_empty()) {
if (auto local_answers = m_etc_hosts.get(name); local_answers.has_value()) {
for (auto& answer : local_answers.value()) {
if (answer.type() == record_type)
responses.append(answer.name().as_string());
}
if (!responses.is_empty())
return responses;
}
if (!name.as_string().is_empty()) {
for (auto& nameserver : m_nameservers) {
#if LOOKUPSERVER_DEBUG
dbgln("Doing lookup using nameserver '{}'", nameserver);

2
Userland/Services/LookupServer/LookupServer.h
View file

@ -52,7 +52,7 @@ private:
RefPtr<Core::LocalServer> m_local_server;
Vector<String> m_nameservers;
HashMap<DNSName, String, DNSName::Traits> m_etc_hosts;
HashMap<DNSName, Vector<DNSAnswer>, DNSName::Traits> m_etc_hosts;
HashMap<DNSName, Vector<DNSAnswer>, DNSName::Traits> m_lookup_cache;
};