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RequestServer+LibDNS: Don't .await() the DNS lookup promise

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...and make sure it will eventually complete (or fail) by adding a
timeout retry sequence.

Fixes an issue where RequestServer would stick around after exit,
waiting for piled up DNS requests for a long time.
This commit is contained in:
Ali Mohammad Pur 2024-11-25 01:04:29 +01:00 • committed by Andreas Kling
parent db29d248ad
commit ff311c1560
Notes: github-actions[bot] 2024-11-25 10:47:30 +00:00
2 changed files with 151 additions and 112 deletions
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79
Libraries/LibDNS/Resolver.h
View file

@ -16,6 +16,7 @@
#include <LibCore/DateTime.h>
#include <LibCore/Promise.h>
#include <LibCore/SocketAddress.h>
#include <LibCore/Timer.h>
#include <LibDNS/Message.h>
#include <LibThreading/MutexProtected.h>
#include <LibThreading/RWLockProtected.h>
@ -112,6 +113,15 @@ private:
};
class Resolver {
struct PendingLookup {
u16 id { 0 };
ByteString name;
WeakPtr<LookupResult> result;
NonnullRefPtr<Core::Promise<NonnullRefPtr<LookupResult const>>> promise;
NonnullRefPtr<Core::Timer> repeat_timer;
size_t times_repeated { 0 };
};
public:
enum class ConnectionMode {
TCP,
@ -203,11 +213,18 @@ public:
return lookup(move(name), class_, Array { Messages::ResourceType::A, Messages::ResourceType::AAAA });
}
NonnullRefPtr<Core::Promise<NonnullRefPtr<LookupResult const>>> lookup(ByteString name, Messages::Class class_, Span<Messages::ResourceType const> desired_types)
NonnullRefPtr<Core::Promise<NonnullRefPtr<LookupResult const>>> lookup(ByteString name, Messages::Class class_, Span<Messages::ResourceType const> desired_types, PendingLookup* repeating_lookup = nullptr)
{
flush_cache();
auto promise = Core::Promise<NonnullRefPtr<LookupResult const>>::construct();
if (repeating_lookup && repeating_lookup->times_repeated >= 5) {
auto promise = repeating_lookup->promise;
promise->reject(Error::from_string_literal("DNS lookup timed out"));
m_pending_lookups.with_write_locked([&](auto& lookups) { lookups->remove(repeating_lookup->id); });
return promise;
}
auto promise = repeating_lookup ? repeating_lookup->promise : Core::Promise<NonnullRefPtr<LookupResult const>>::construct();
if (auto maybe_ipv4 = IPv4Address::from_string(name); maybe_ipv4.has_value()) {
if (desired_types.contains_slow(Messages::ResourceType::A)) {
@ -302,11 +319,16 @@ public:
}
Messages::Message query;
m_pending_lookups.with_read_locked([&](auto& lookups) {
do
fill_with_random({ &query.header.id, sizeof(query.header.id) });
while (lookups->find(query.header.id) != nullptr);
});
if (repeating_lookup) {
query.header.id = repeating_lookup->id;
repeating_lookup->times_repeated++;
} else {
m_pending_lookups.with_read_locked([&](auto& lookups) {
do
fill_with_random({ &query.header.id, sizeof(query.header.id) });
while (lookups->find(query.header.id) != nullptr);
});
}
query.header.question_count = max(1u, desired_types.size());
query.header.options.set_response_code(Messages::Options::ResponseCode::NoError);
query.header.options.set_recursion_desired(true);
@ -327,21 +349,44 @@ public:
});
}
auto cached_entry = m_pending_lookups.with_write_locked([&](auto& pending_lookups) -> RefPtr<Core::Promise<NonnullRefPtr<LookupResult const>>> {
auto cached_entry = repeating_lookup ? nullptr : m_pending_lookups.with_write_locked([&](auto& pending_lookups) -> PendingLookup* {
// One more try to make sure we're not overwriting an existing lookup
if (cached_result_id.has_value()) {
if (auto* lookup = pending_lookups->find(*cached_result_id))
return lookup->promise;
return lookup;
}
pending_lookups->insert(query.header.id, { query.header.id, name, result->make_weak_ptr(), promise });
pending_lookups->insert(query.header.id, { query.header.id, name, result->make_weak_ptr(), promise, Core::Timer::create(), 0 });
auto p = pending_lookups->find(query.header.id);
p->repeat_timer->set_single_shot(true);
p->repeat_timer->set_interval(1000);
p->repeat_timer->on_timeout = [=, this] {
(void)lookup(name, class_, desired_types, p);
};
return nullptr;
});
if (cached_entry) {
dbgln_if(DNS_DEBUG, "DNS::lookup({}) -> Already in cache", name);
return cached_entry.release_nonnull();
dbgln_if(DNS_DEBUG, "DNS::lookup({}) -> Lookup already underway", name);
auto user_promise = Core::Promise<NonnullRefPtr<LookupResult const>>::construct();
promise->on_resolution = [user_promise, cached_promise = cached_entry->promise](auto& result) {
user_promise->resolve(*result);
cached_promise->resolve(*result);
return ErrorOr<void> {};
};
promise->on_rejection = [user_promise, cached_promise = cached_entry->promise](auto& error) {
user_promise->reject(Error::copy(error));
cached_promise->reject(Error::copy(error));
};
cached_entry->promise = move(promise);
return user_promise;
}
auto pending_lookup = m_pending_lookups.with_write_locked([&](auto& lookups) -> PendingLookup* {
return lookups->find(query.header.id);
});
ByteBuffer query_bytes;
MUST(query.to_raw(query_bytes));
@ -361,17 +406,12 @@ public:
return promise;
}
pending_lookup->repeat_timer->start();
return promise;
}
private:
struct PendingLookup {
u16 id { 0 };
ByteString name;
WeakPtr<LookupResult> result;
NonnullRefPtr<Core::Promise<NonnullRefPtr<LookupResult const>>> promise;
};
ErrorOr<Messages::Message> parse_one_message()
{
if (m_mode == ConnectionMode::UDP)
@ -407,6 +447,7 @@ private:
if (!lookup)
return Error::from_string_literal("No pending lookup found for this message");
lookup->repeat_timer->stop();
if (lookup->result.is_null())
return {}; // Message is a response to a lookup that's been purged from the cache, ignore it

184
Services/RequestServer/ConnectionFromClient.cpp
View file

@ -344,120 +344,118 @@ void ConnectionFromClient::start_request(i32 request_id, ByteString const& metho
}
auto host = url.serialized_host().value().to_byte_string();
auto dns_promise = m_resolver->dns.lookup(host, DNS::Messages::Class::IN, Array { DNS::Messages::ResourceType::A, DNS::Messages::ResourceType::AAAA }.span());
auto resolve_result = dns_promise->await();
if (resolve_result.is_error()) {
dbgln("StartRequest: DNS lookup failed for '{}': {}", host, resolve_result.error());
async_request_finished(request_id, 0, Requests::NetworkError::UnableToResolveHost);
return;
}
m_resolver->dns.lookup(host, DNS::Messages::Class::IN, Array { DNS::Messages::ResourceType::A, DNS::Messages::ResourceType::AAAA }.span())
->when_rejected([this, request_id](auto const& error) {
dbgln("StartRequest: DNS lookup failed: {}", error);
async_request_finished(request_id, 0, Requests::NetworkError::UnableToResolveHost);
})
.when_resolved([this, request_id, host, url, method, request_body, request_headers, proxy_data](auto const& dns_result) {
if (dns_result->records().is_empty()) {
dbgln("StartRequest: DNS lookup failed for '{}'", host);
async_request_finished(request_id, 0, Requests::NetworkError::UnableToResolveHost);
return;
}
auto dns_result = resolve_result.release_value();
if (dns_result->records().is_empty()) {
dbgln("StartRequest: DNS lookup failed for '{}'", host);
async_request_finished(request_id, 0, Requests::NetworkError::UnableToResolveHost);
return;
}
auto* easy = curl_easy_init();
if (!easy) {
dbgln("StartRequest: Failed to initialize curl easy handle");
return;
}
auto* easy = curl_easy_init();
if (!easy) {
dbgln("StartRequest: Failed to initialize curl easy handle");
return;
}
auto fds_or_error = Core::System::pipe2(O_NONBLOCK);
if (fds_or_error.is_error()) {
dbgln("StartRequest: Failed to create pipe: {}", fds_or_error.error());
return;
}
auto fds_or_error = Core::System::pipe2(O_NONBLOCK);
if (fds_or_error.is_error()) {
dbgln("StartRequest: Failed to create pipe: {}", fds_or_error.error());
return;
}
auto fds = fds_or_error.release_value();
auto writer_fd = fds[1];
auto reader_fd = fds[0];
async_request_started(request_id, IPC::File::adopt_fd(reader_fd));
auto fds = fds_or_error.release_value();
auto writer_fd = fds[1];
auto reader_fd = fds[0];
async_request_started(request_id, IPC::File::adopt_fd(reader_fd));
auto request = make<ActiveRequest>(*this, m_curl_multi, easy, request_id, writer_fd);
request->url = url.to_string().value();
auto request = make<ActiveRequest>(*this, m_curl_multi, easy, request_id, writer_fd);
request->url = url.to_string().value();
auto set_option = [easy](auto option, auto value) {
auto result = curl_easy_setopt(easy, option, value);
if (result != CURLE_OK) {
dbgln("StartRequest: Failed to set curl option: {}", curl_easy_strerror(result));
return false;
}
return true;
};
auto set_option = [easy](auto option, auto value) {
auto result = curl_easy_setopt(easy, option, value);
if (result != CURLE_OK) {
dbgln("StartRequest: Failed to set curl option: {}", curl_easy_strerror(result));
return false;
}
return true;
};
set_option(CURLOPT_PRIVATE, request.ptr());
set_option(CURLOPT_PRIVATE, request.ptr());
if (!g_default_certificate_path.is_empty())
set_option(CURLOPT_CAINFO, g_default_certificate_path.characters());
if (!g_default_certificate_path.is_empty())
set_option(CURLOPT_CAINFO, g_default_certificate_path.characters());
set_option(CURLOPT_ACCEPT_ENCODING, "gzip, deflate, br");
set_option(CURLOPT_URL, url.to_string().value().to_byte_string().characters());
set_option(CURLOPT_PORT, url.port_or_default());
set_option(CURLOPT_CONNECTTIMEOUT, s_connect_timeout_seconds);
set_option(CURLOPT_ACCEPT_ENCODING, "gzip, deflate, br");
set_option(CURLOPT_URL, url.to_string().value().to_byte_string().characters());
set_option(CURLOPT_PORT, url.port_or_default());
set_option(CURLOPT_CONNECTTIMEOUT, s_connect_timeout_seconds);
bool did_set_body = false;
bool did_set_body = false;
if (method == "GET"sv) {
set_option(CURLOPT_HTTPGET, 1L);
} else if (method.is_one_of("POST"sv, "PUT"sv, "PATCH"sv, "DELETE"sv)) {
request->body = request_body;
set_option(CURLOPT_POSTFIELDSIZE, request->body.size());
set_option(CURLOPT_POSTFIELDS, request->body.data());
did_set_body = true;
} else if (method == "HEAD") {
set_option(CURLOPT_NOBODY, 1L);
}
set_option(CURLOPT_CUSTOMREQUEST, method.characters());
if (method == "GET"sv) {
set_option(CURLOPT_HTTPGET, 1L);
} else if (method.is_one_of("POST"sv, "PUT"sv, "PATCH"sv, "DELETE"sv)) {
request->body = request_body;
set_option(CURLOPT_POSTFIELDSIZE, request->body.size());
set_option(CURLOPT_POSTFIELDS, request->body.data());
did_set_body = true;
} else if (method == "HEAD") {
set_option(CURLOPT_NOBODY, 1L);
}
set_option(CURLOPT_CUSTOMREQUEST, method.characters());
set_option(CURLOPT_FOLLOWLOCATION, 0);
set_option(CURLOPT_FOLLOWLOCATION, 0);
struct curl_slist* curl_headers = nullptr;
struct curl_slist* curl_headers = nullptr;
// NOTE: CURLOPT_POSTFIELDS automatically sets the Content-Type header.
// Set it to empty if the headers passed in don't contain a content type.
if (did_set_body && !request_headers.contains("Content-Type"))
curl_headers = curl_slist_append(curl_headers, "Content-Type:");
// NOTE: CURLOPT_POSTFIELDS automatically sets the Content-Type header.
// Set it to empty if the headers passed in don't contain a content type.
if (did_set_body && !request_headers.contains("Content-Type"))
curl_headers = curl_slist_append(curl_headers, "Content-Type:");
for (auto const& header : request_headers.headers()) {
auto header_string = ByteString::formatted("{}: {}", header.name, header.value);
curl_headers = curl_slist_append(curl_headers, header_string.characters());
}
set_option(CURLOPT_HTTPHEADER, curl_headers);
for (auto const& header : request_headers.headers()) {
auto header_string = ByteString::formatted("{}: {}", header.name, header.value);
curl_headers = curl_slist_append(curl_headers, header_string.characters());
}
set_option(CURLOPT_HTTPHEADER, curl_headers);
// FIXME: Set up proxy if applicable
(void)proxy_data;
// FIXME: Set up proxy if applicable
(void)proxy_data;
set_option(CURLOPT_WRITEFUNCTION, &on_data_received);
set_option(CURLOPT_WRITEDATA, reinterpret_cast<void*>(request.ptr()));
set_option(CURLOPT_WRITEFUNCTION, &on_data_received);
set_option(CURLOPT_WRITEDATA, reinterpret_cast<void*>(request.ptr()));
set_option(CURLOPT_HEADERFUNCTION, &on_header_received);
set_option(CURLOPT_HEADERDATA, reinterpret_cast<void*>(request.ptr()));
set_option(CURLOPT_HEADERFUNCTION, &on_header_received);
set_option(CURLOPT_HEADERDATA, reinterpret_cast<void*>(request.ptr()));
StringBuilder resolve_opt_builder;
resolve_opt_builder.appendff("{}:{}:", host, url.port_or_default());
auto first = true;
for (auto& addr : dns_result->cached_addresses()) {
auto formatted_address = addr.visit(
[&](IPv4Address const& ipv4) { return ipv4.to_byte_string(); },
[&](IPv6Address const& ipv6) { return MUST(ipv6.to_string()).to_byte_string(); });
if (!first)
resolve_opt_builder.append(',');
first = false;
resolve_opt_builder.append(formatted_address);
}
StringBuilder resolve_opt_builder;
resolve_opt_builder.appendff("{}:{}:", host, url.port_or_default());
auto first = true;
for (auto& addr : dns_result->cached_addresses()) {
auto formatted_address = addr.visit(
[&](IPv4Address const& ipv4) { return ipv4.to_byte_string(); },
[&](IPv6Address const& ipv6) { return MUST(ipv6.to_string()).to_byte_string(); });
if (!first)
resolve_opt_builder.append(',');
first = false;
resolve_opt_builder.append(formatted_address);
}
auto formatted_address = resolve_opt_builder.to_byte_string();
g_dns_cache.set(host, formatted_address);
curl_slist* resolve_list = curl_slist_append(nullptr, formatted_address.characters());
curl_easy_setopt(easy, CURLOPT_RESOLVE, resolve_list);
auto formatted_address = resolve_opt_builder.to_byte_string();
g_dns_cache.set(host, formatted_address);
curl_slist* resolve_list = curl_slist_append(nullptr, formatted_address.characters());
curl_easy_setopt(easy, CURLOPT_RESOLVE, resolve_list);
auto result = curl_multi_add_handle(m_curl_multi, easy);
VERIFY(result == CURLM_OK);
auto result = curl_multi_add_handle(m_curl_multi, easy);
VERIFY(result == CURLM_OK);
m_active_requests.set(request_id, move(request));
m_active_requests.set(request_id, move(request));
});
}
static Requests::NetworkError map_curl_code_to_network_error(CURLcode const& code)