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#pragma once
#include <Poco/Net/IPAddress.h>
#include <Poco/Net/SocketAddress.h>
#include <memory>
#include <base/types.h>
#include <Core/Names.h>
#include <boost/noncopyable.hpp>
#include <Common/LoggingFormatStringHelpers.h>
namespace Poco { class Logger; }
namespace DB
{
/// A singleton implementing DNS names resolving with optional DNS cache
/// The cache is being updated asynchronous in separate thread (see DNSCacheUpdater)
/// or it could be updated manually via drop() method.
class DNSResolver : private boost::noncopyable
{
public:
using IPAddresses = std::vector<Poco::Net::IPAddress>;
using IPAddressesPtr = std::shared_ptr<IPAddresses>;
static DNSResolver & instance();
DNSResolver(const DNSResolver &) = delete;
/// Accepts host names like 'example.com' or '127.0.0.1' or '::1' and resolves its IP
Poco::Net::IPAddress resolveHost(const std::string & host);
/// Accepts host names like 'example.com' or '127.0.0.1' or '::1' and resolves all its IPs
IPAddresses resolveHostAll(const std::string & host);
/// Accepts host names like 'example.com:port' or '127.0.0.1:port' or '[::1]:port' and resolves its IP and port
Poco::Net::SocketAddress resolveAddress(const std::string & host_and_port);
Poco::Net::SocketAddress resolveAddress(const std::string & host, UInt16 port);
std::vector<Poco::Net::SocketAddress> resolveAddressList(const std::string & host, UInt16 port);
/// Accepts host IP and resolves its host names
std::unordered_set<String> reverseResolve(const Poco::Net::IPAddress & address);
/// Get this server host name
String getHostName();
/// Disables caching
void setDisableCacheFlag(bool is_disabled = true);
/// Drops all caches
void dropCache();
/// Removes an entry from cache or does nothing
void removeHostFromCache(const std::string & host);
/// Updates all known hosts in cache.
/// Returns true if IP of any host has been changed or an element was dropped (too many failures)
bool updateCache(UInt32 max_consecutive_failures);
~DNSResolver();
private:
template <typename UpdateF, typename ElemsT>
bool updateCacheImpl(
UpdateF && update_func,
ElemsT && elems,
UInt32 max_consecutive_failures,
FormatStringHelper<String> notfound_log_msg,
FormatStringHelper<String> dropped_log_msg);
DNSResolver();
struct Impl;
std::unique_ptr<Impl> impl;
Poco::Logger * log;
/// Updates cached value and returns true it has been changed.
bool updateHost(const String & host);
bool updateAddress(const Poco::Net::IPAddress & address);
void addToNewHosts(const String & host);
void addToNewAddresses(const Poco::Net::IPAddress & address);
};
}
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