Resolver.h

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/*
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 */
 
#ifndef FACEBOOK_NETWORK_RESOLVER_H
#define FACEBOOK_NETWORK_RESOLVER_H
 
#include "ocean/network/Network.h"
#include "ocean/network/Address4.h"
 
#include "ocean/base/Lock.h"
#include "ocean/base/Singleton.h"
 
namespace Ocean
{
 
namespace Network
{
 
/**
 * This class implements an address resolver.
 * @ingroup network
 */
class OCEAN_NETWORK_EXPORT Resolver : public Singleton<Resolver>
{
    friend class Singleton<Resolver>;
 
    public:
 
        /**
         * Definition of a vector holding addresses.
         */
        typedef std::vector<Address4> Addresses4;
 
        /**
         * Definition of an unordered set holding addresses.
         */
        typedef std::unordered_set<Address4, Address4> AddressSet4;
 
    public:
 
        /**
         * Returns all current local addresses.
         * @return The local addresses of the system, empty if unknown
         */
        Addresses4 localAddresses() const;
 
        /**
         * Adds an explicit local address.
         * @param localAddress The explicit local address to be set, must be valid
         */
        void addLocalAddress(const Address4& localAddress);
 
        /**
         * Resolves a given host name to it's first found ip4 address.
         * @param host Name of the host to resolve
         * @return Resolved address, a zero address is returned if the host could not be resolved
         */
        static Address4 resolveFirstIp4(const std::string& host);
 
        /**
         * Resolves a given host name to all possible ip4 addresses.
         * @param host Name of the host to resolve
         * @return Resolved addresses
         */
        static Addresses4 resolveIp4(const std::string& host);
 
        /**
         * Resolves a given address to it's host name.
         * If the address could not be resolved an empty string is returned.
         * @param address Address4 to resolve
         * @return Resolved host name
         */
        static std::string resolve(const Address4& address);
 
    protected:
 
        /**
         * Creates a new resolver object.
         */
        Resolver();
 
    protected:
 
        /// The local addresses explicitly set.
        AddressSet4 explicitLocalAddresses_;
 
        /// The resolver's lock.
        mutable Lock lock_;
};
 
}
 
}
 
#endif // FACEBOOK_NETWORK_RESOLVER_H