/*
* Copyright (c) 2013-2022, The PurpleI2P Project
*
* This file is part of Purple i2pd project and licensed under BSD3
*
* See full license text in LICENSE file at top of project tree
*/

#include <string.h>
#include <inttypes.h>
#include <string>
#include <map>
#include <fstream>
#include <chrono>
#include <condition_variable>
#include <openssl/rand.h>
#include <boost/algorithm/string.hpp>
#include <boost/filesystem.hpp>
#include "Base.h"
#include "util.h"
#include "Identity.h"
#include "FS.h"
#include "Log.h"
#include "HTTP.h"
#include "NetDb.hpp"
#include "ClientContext.h"
#include "AddressBook.h"
#include "Config.h"

namespace i2p {
    namespace client {
        // TODO: this is actually proxy class
        class AddressBookFilesystemStorage : public AddressBookStorage {
        public:

            AddressBookFilesystemStorage() : storage("addressbook", "b", "", "b32") {
                i2p::config::GetOption("persist.addressbook", m_IsPersist);
                if (m_IsPersist)
                    i2p::config::GetOption("addressbook.hostsfile", m_HostsFile);
            }

            std::shared_ptr<const i2p::data::IdentityEx> GetAddress(const i2p::data::IdentHash &ident) const;

            void AddAddress(std::shared_ptr<const i2p::data::IdentityEx> address);

            void RemoveAddress(const i2p::data::IdentHash &ident);

            bool Init();

            int Load(std::map <std::string, std::shared_ptr<Address>> &addresses);

            int LoadLocal(std::map <std::string, std::shared_ptr<Address>> &addresses);

            int Save(const std::map <std::string, std::shared_ptr<Address>> &addresses);

            void
            SaveEtag(const i2p::data::IdentHash &subsciption, const std::string &etag, const std::string &lastModified);

            bool GetEtag(const i2p::data::IdentHash &subscription, std::string &etag, std::string &lastModified);

            void ResetEtags();

        private:

            int LoadFromFile(const std::string &filename,
                             std::map <std::string, std::shared_ptr<Address>> &addresses); // returns -1 if can't open file, otherwise number of records

        private:

            i2p::fs::HashedStorage storage;
            std::string etagsPath, indexPath, localPath;
            bool m_IsPersist;
            std::string m_HostsFile; // file to dump hosts.txt, empty if not used
        };

        bool AddressBookFilesystemStorage::Init() {
            storage.SetPlace(i2p::fs::GetDataDir());
            // init storage
            if (storage.Init(i2p::data::GetBase32SubstitutionTable(), 32)) {
                // init ETags
                etagsPath = i2p::fs::StorageRootPath(storage, "etags");
                if (!i2p::fs::Exists(etagsPath))
                    i2p::fs::CreateDirectory(etagsPath);
                // init address files
                indexPath = i2p::fs::StorageRootPath(storage, "addresses.csv");
                localPath = i2p::fs::StorageRootPath(storage, "local.csv");
                return true;
            }
            return false;
        }

        std::shared_ptr<const i2p::data::IdentityEx>
        AddressBookFilesystemStorage::GetAddress(const i2p::data::IdentHash &ident) const {
            if (!m_IsPersist) {
                LogPrint(eLogDebug, "Addressbook: Persistence is disabled");
                return nullptr;
            }
            std::string filename = storage.Path(ident.ToBase32());
            std::ifstream f(filename, std::ifstream::binary);
            if (!f.is_open()) {
                LogPrint(eLogDebug, "Addressbook: Requested, but not found: ", filename);
                return nullptr;
            }

            f.seekg(0, std::ios::end);
            size_t len = f.tellg();
            if (len < i2p::data::DEFAULT_IDENTITY_SIZE) {
                LogPrint(eLogError, "Addressbook: File ", filename, " is too short: ", len);
                return nullptr;
            }
            f.seekg(0, std::ios::beg);
            uint8_t *buf = new uint8_t[len];
            f.read((char *) buf, len);
            auto address = std::make_shared<i2p::data::IdentityEx>(buf, len);
            delete[] buf;
            return address;
        }

        void AddressBookFilesystemStorage::AddAddress(std::shared_ptr<const i2p::data::IdentityEx> address) {
            if (!m_IsPersist) return;
            std::string path = storage.Path(address->GetIdentHash().ToBase32());
            std::ofstream f(path, std::ofstream::binary | std::ofstream::out);
            if (!f.is_open()) {
                LogPrint(eLogError, "Addressbook: Can't open file ", path);
                return;
            }
            size_t len = address->GetFullLen();
            uint8_t *buf = new uint8_t[len];
            address->ToBuffer(buf, len);
            f.write((char *) buf, len);
            delete[] buf;
        }

        void AddressBookFilesystemStorage::RemoveAddress(const i2p::data::IdentHash &ident) {
            if (!m_IsPersist) return;
            storage.Remove(ident.ToBase32());
        }

        int AddressBookFilesystemStorage::LoadFromFile(const std::string &filename,
                                                       std::map <std::string, std::shared_ptr<Address>> &addresses) {
            int num = 0;
            std::ifstream f(filename, std::ifstream::in); // in text mode
            if (!f) return -1;

            addresses.clear();
            while (!f.eof()) {
                std::string s;
                getline(f, s);
                if (!s.length()) continue; // skip empty line

                std::size_t pos = s.find(',');
                if (pos != std::string::npos) {
                    std::string name = s.substr(0, pos++);
                    std::string addr = s.substr(pos);

                    addresses[name] = std::make_shared<Address>(addr);
                    num++;
                }
            }
            return num;
        }

        int AddressBookFilesystemStorage::Load(std::map <std::string, std::shared_ptr<Address>> &addresses) {
            int num = LoadFromFile(indexPath, addresses);
            if (num < 0) {
                LogPrint(eLogWarning, "Addressbook: Can't open ", indexPath);
                return 0;
            }
            LogPrint(eLogInfo, "Addressbook: Using index file ", indexPath);
            LogPrint(eLogInfo, "Addressbook: ", num, " addresses loaded from storage");

            return num;
        }

        int AddressBookFilesystemStorage::LoadLocal(std::map <std::string, std::shared_ptr<Address>> &addresses) {
            int num = LoadFromFile(localPath, addresses);
            if (num < 0) return 0;
            LogPrint(eLogInfo, "Addressbook: ", num, " local addresses loaded");
            return num;
        }

        int AddressBookFilesystemStorage::Save(const std::map <std::string, std::shared_ptr<Address>> &addresses) {
            if (addresses.empty()) {
                LogPrint(eLogWarning, "Addressbook: Not saving empty addressbook");
                return 0;
            }

            int num = 0;
            {
                // save index file
                std::ofstream f(indexPath, std::ofstream::out); // in text mode
                if (f.is_open()) {
                    for (const auto &it: addresses) {
                        if (it.second->IsValid()) {
                            f << it.first << ",";
                            if (it.second->IsIdentHash())
                                f << it.second->identHash.ToBase32();
                            else
                                f << it.second->blindedPublicKey->ToB33();
                            f << std::endl;
                            num++;
                        } else
                            LogPrint(eLogWarning, "Addressbook: Invalid address ", it.first);
                    }
                    LogPrint(eLogInfo, "Addressbook: ", num, " addresses saved");
                } else
                    LogPrint(eLogWarning, "Addressbook: Can't open ", indexPath);
            }
            if (!m_HostsFile.empty()) {
                // dump full hosts.txt
                std::ofstream f(m_HostsFile, std::ofstream::out); // in text mode
                if (f.is_open()) {
                    for (const auto &it: addresses) {
                        std::shared_ptr<const i2p::data::IdentityEx> addr;
                        if (it.second->IsIdentHash()) {
                            addr = GetAddress(it.second->identHash);
                            if (addr)
                                f << it.first << "=" << addr->ToBase64() << std::endl;
                        }
                    }
                } else
                    LogPrint(eLogWarning, "Addressbook: Can't open ", m_HostsFile);
            }

            return num;
        }

        void AddressBookFilesystemStorage::SaveEtag(const i2p::data::IdentHash &subscription, const std::string &etag,
                                                    const std::string &lastModified) {
            std::string fname = etagsPath + i2p::fs::dirSep + subscription.ToBase32() + ".txt";
            std::ofstream f(fname, std::ofstream::out | std::ofstream::trunc);
            if (f) {
                f << etag << std::endl;
                f << lastModified << std::endl;
            }
        }

        bool AddressBookFilesystemStorage::GetEtag(const i2p::data::IdentHash &subscription, std::string &etag,
                                                   std::string &lastModified) {
            std::string fname = etagsPath + i2p::fs::dirSep + subscription.ToBase32() + ".txt";
            std::ifstream f(fname, std::ofstream::in);
            if (!f || f.eof()) return false;
            std::getline(f, etag);
            if (f.eof()) return false;
            std::getline(f, lastModified);
            return true;
        }

        void AddressBookFilesystemStorage::ResetEtags() {
            LogPrint(eLogError, "Addressbook: Resetting eTags");
            for (boost::filesystem::directory_iterator it(etagsPath);
                 it != boost::filesystem::directory_iterator(); ++it) {
                if (!boost::filesystem::is_regular_file(it->status()))
                    continue;
                boost::filesystem::remove(it->path());
            }
        }

//---------------------------------------------------------------------

        Address::Address(const std::string &b32) :
                addressType(eAddressInvalid) {
            if (b32.length() <= B33_ADDRESS_THRESHOLD) {
                if (identHash.FromBase32(b32) > 0)
                    addressType = eAddressIndentHash;
            } else {
                blindedPublicKey = std::make_shared<i2p::data::BlindedPublicKey>(b32);
                if (blindedPublicKey->IsValid())
                    addressType = eAddressBlindedPublicKey;
            }
        }

        Address::Address(const i2p::data::IdentHash &hash) {
            addressType = eAddressIndentHash;
            identHash = hash;
        }

        AddressBook::AddressBook() : m_Storage(nullptr), m_IsLoaded(false), m_IsDownloading(false),
                                     m_NumRetries(0), m_DefaultSubscription(nullptr),
                                     m_SubscriptionsUpdateTimer(nullptr),
                                     m_IsEnabled(true) {
        }

        AddressBook::~AddressBook() {
            Stop();
        }

        void AddressBook::Start() {
            i2p::config::GetOption("addressbook.enabled", m_IsEnabled);
            if (m_IsEnabled) {
                if (!m_Storage)
                    m_Storage = new AddressBookFilesystemStorage;
                m_Storage->Init();
                LoadHosts(); /* try storage, then hosts.txt, then download */
                StartSubscriptions();
                StartLookups();
            }
        }

        void AddressBook::StartResolvers() {
            LoadLocal();
        }

        void AddressBook::Stop() {
            StopLookups();
            StopSubscriptions();
            if (m_SubscriptionsUpdateTimer) {
                delete m_SubscriptionsUpdateTimer;
                m_SubscriptionsUpdateTimer = nullptr;
            }
            if (m_IsDownloading) {
                LogPrint(eLogInfo, "Addressbook: Subscriptions are downloading, abort");
                for (int i = 0; i < 30; i++) {
                    if (!m_IsDownloading) {
                        LogPrint(eLogInfo, "Addressbook: Subscriptions download complete");
                        break;
                    }
                    std::this_thread::sleep_for(std::chrono::seconds(1)); // wait for 1 seconds
                }
                LogPrint(eLogError, "Addressbook: Subscription download timeout");
                m_IsDownloading = false;
            }
            if (m_Storage) {
                m_Storage->Save(m_Addresses);
                delete m_Storage;
                m_Storage = nullptr;
            }
            m_DefaultSubscription = nullptr;
            m_Subscriptions.clear();
        }

        std::shared_ptr<const Address> AddressBook::GetAddress(const std::string &address) {
            auto pos = address.find(".b32.i2p");
            if (pos != std::string::npos) {
                auto addr = std::make_shared<const Address>(address.substr(0, pos));
                return addr->IsValid() ? addr : nullptr;
            } else {
                pos = address.find(".i2p");
                if (pos != std::string::npos) {
                    if (!m_IsEnabled) return nullptr;
                    auto addr = FindAddress(address);
                    if (!addr)
                        LookupAddress(address); // TODO:
                    return addr;
                }
            }
            // if not .b32 we assume full base64 address
            i2p::data::IdentityEx dest;
            if (!dest.FromBase64(address))
                return nullptr;
            return std::make_shared<const Address>(dest.GetIdentHash());
        }

        std::shared_ptr<const Address> AddressBook::FindAddress(const std::string &address) {
            auto it = m_Addresses.find(address);
            if (it != m_Addresses.end())
                return it->second;
            return nullptr;
        }

        void AddressBook::InsertAddress(const std::string &address, const std::string &jump) {
            auto pos = jump.find(".b32.i2p");
            if (pos != std::string::npos) {
                m_Addresses[address] = std::make_shared<Address>(jump.substr(0, pos));
                LogPrint(eLogInfo, "Addressbook: Added ", address, " -> ", jump);
            } else {
                // assume base64
                auto ident = std::make_shared<i2p::data::IdentityEx>();
                if (ident->FromBase64(jump)) {
                    m_Storage->AddAddress(ident);
                    m_Addresses[address] = std::make_shared<Address>(ident->GetIdentHash());
                    LogPrint(eLogInfo, "Addressbook: Added ", address, " -> ", ToAddress(ident->GetIdentHash()));
                } else
                    LogPrint(eLogError, "Addressbook: Malformed address ", jump);
            }
        }

        void AddressBook::InsertFullAddress(std::shared_ptr<const i2p::data::IdentityEx> address) {
            m_Storage->AddAddress(address);
        }

        std::shared_ptr<const i2p::data::IdentityEx> AddressBook::GetFullAddress(const std::string &address) {
            auto addr = GetAddress(address);
            if (!addr || !addr->IsIdentHash()) return nullptr;
            return m_Storage->GetAddress(addr->identHash);
        }

        void AddressBook::LoadHosts() {
            if (m_Storage->Load(m_Addresses) > 0) {
                m_IsLoaded = true;
                return;
            }

            // then try hosts.txt
            std::ifstream f(i2p::fs::DataDirPath("hosts.txt"), std::ifstream::in); // in text mode
            if (f.is_open()) {
                LoadHostsFromStream(f, false);
                m_IsLoaded = true;
            }

            // reset eTags, because we don’t know how old hosts.txt is or can't load addressbook
            m_Storage->ResetEtags();
        }

        bool AddressBook::LoadHostsFromStream(std::istream &f, bool is_update) {
            std::unique_lock <std::mutex> l(m_AddressBookMutex);
            int numAddresses = 0;
            bool incomplete = false;
            std::string s;
            while (!f.eof()) {
                getline(f, s);

                if (!s.length() || s[0] == '#')
                    continue; // skip empty or comment line

                size_t pos = s.find('=');

                if (pos != std::string::npos) {
                    std::string name = s.substr(0, pos++);
                    std::string addr = s.substr(pos);

                    size_t pos = addr.find('#');
                    if (pos != std::string::npos)
                        addr = addr.substr(0, pos); // remove comments

                    pos = name.find(".b32.i2p");
                    if (pos != std::string::npos) {
                        LogPrint(eLogError, "Addressbook: Skipped adding of b32 address: ", name);
                        continue;
                    }

                    pos = name.find(".i2p");
                    if (pos == std::string::npos) {
                        LogPrint(eLogError, "Addressbook: Malformed domain: ", name);
                        continue;
                    }

                    auto ident = std::make_shared<i2p::data::IdentityEx>();
                    if (!ident->FromBase64(addr)) {
                        LogPrint(eLogError, "Addressbook: Malformed address ", addr, " for ", name);
                        incomplete = f.eof();
                        continue;
                    }
                    numAddresses++;
                    auto it = m_Addresses.find(name);
                    if (it != m_Addresses.end()) // already exists ?
                    {
                        if (it->second->IsIdentHash() && it->second->identHash != ident->GetIdentHash() &&
                            // address changed?
                            ident->GetSigningKeyType() != i2p::data::SIGNING_KEY_TYPE_DSA_SHA1) // don't replace by DSA
                        {
                            it->second->identHash = ident->GetIdentHash();
                            m_Storage->AddAddress(ident);
                            m_Storage->RemoveAddress(it->second->identHash);
                            LogPrint(eLogInfo, "Addressbook: Updated host: ", name);
                        }
                    } else {
                        m_Addresses.emplace(name, std::make_shared<Address>(ident->GetIdentHash()));
                        m_Storage->AddAddress(ident);
                        if (is_update)
                            LogPrint(eLogInfo, "Addressbook: Added new host: ", name);
                    }
                } else
                    incomplete = f.eof();
            }
            LogPrint(eLogInfo, "Addressbook: ", numAddresses, " addresses processed");
            if (numAddresses > 0) {
                if (!incomplete) m_IsLoaded = true;
                m_Storage->Save(m_Addresses);
            }
            return !incomplete;
        }

        void AddressBook::LoadSubscriptions() {
            if (!m_Subscriptions.size()) {
                std::ifstream f(i2p::fs::DataDirPath("subscriptions.txt"), std::ifstream::in); // in text mode
                if (f.is_open()) {
                    std::string s;
                    while (!f.eof()) {
                        getline(f, s);
                        if (s.empty() || s[0] == '#') continue; // skip empty line or comment
                        m_Subscriptions.push_back(std::make_shared<AddressBookSubscription>(*this, s));
                    }
                    LogPrint(eLogInfo, "Addressbook: ", m_Subscriptions.size(), " subscriptions urls loaded");
                    LogPrint(eLogWarning,
                             "Addressbook: subscriptions.txt usage is deprecated, use config file instead");
                } else {
                    LogPrint(eLogInfo, "Addressbook: Loading subscriptions from config file");
                    // using config file items
                    std::string subscriptionURLs;
                    i2p::config::GetOption("addressbook.subscriptions", subscriptionURLs);
                    std::vector <std::string> subsList;
                    boost::split(subsList, subscriptionURLs, boost::is_any_of(","), boost::token_compress_on);

                    for (const auto &s: subsList) {
                        m_Subscriptions.push_back(std::make_shared<AddressBookSubscription>(*this, s));
                    }
                    LogPrint(eLogInfo, "Addressbook: ", m_Subscriptions.size(), " subscriptions urls loaded");
                }
            } else
                LogPrint(eLogError, "Addressbook: Subscriptions already loaded");
        }

        void AddressBook::LoadLocal() {
            std::map <std::string, std::shared_ptr<Address>> localAddresses;
            m_Storage->LoadLocal(localAddresses);
            for (const auto &it: localAddresses) {
                if (!it.second->IsIdentHash()) continue; // skip blinded for now
                auto dot = it.first.find('.');
                if (dot != std::string::npos) {
                    auto domain = it.first.substr(dot + 1);
                    auto it1 = m_Addresses.find(domain); // find domain in our addressbook
                    if (it1 != m_Addresses.end() && it1->second->IsIdentHash()) {
                        auto dest = context.FindLocalDestination(it1->second->identHash);
                        if (dest) {
                            // address is ours
                            std::shared_ptr <AddressResolver> resolver;
                            auto it2 = m_Resolvers.find(it1->second->identHash);
                            if (it2 != m_Resolvers.end())
                                resolver = it2->second; // resolver exists
                            else {
                                // create new resolver
                                resolver = std::make_shared<AddressResolver>(dest);
                                m_Resolvers.insert(std::make_pair(it1->second->identHash, resolver));
                            }
                            resolver->AddAddress(it.first, it.second->identHash);
                        }
                    }
                }
            }
        }

        bool
        AddressBook::GetEtag(const i2p::data::IdentHash &subscription, std::string &etag, std::string &lastModified) {
            if (m_Storage)
                return m_Storage->GetEtag(subscription, etag, lastModified);
            else
                return false;
        }

        void
        AddressBook::DownloadComplete(bool success, const i2p::data::IdentHash &subscription, const std::string &etag,
                                      const std::string &lastModified) {
            m_IsDownloading = false;
            m_NumRetries++;
            int nextUpdateTimeout = m_NumRetries * CONTINIOUS_SUBSCRIPTION_RETRY_TIMEOUT;
            if (m_NumRetries > CONTINIOUS_SUBSCRIPTION_MAX_NUM_RETRIES ||
                nextUpdateTimeout > CONTINIOUS_SUBSCRIPTION_UPDATE_TIMEOUT)
                nextUpdateTimeout = CONTINIOUS_SUBSCRIPTION_UPDATE_TIMEOUT;
            if (success) {
                m_NumRetries = 0;
                if (m_DefaultSubscription) m_DefaultSubscription = nullptr;
                if (m_IsLoaded)
                    nextUpdateTimeout = CONTINIOUS_SUBSCRIPTION_UPDATE_TIMEOUT;
                else
                    m_IsLoaded = true;
                if (m_Storage) m_Storage->SaveEtag(subscription, etag, lastModified);
            }
            if (m_SubscriptionsUpdateTimer) {
                m_SubscriptionsUpdateTimer->expires_from_now(boost::posix_time::minutes(nextUpdateTimeout));
                m_SubscriptionsUpdateTimer->async_wait(std::bind(&AddressBook::HandleSubscriptionsUpdateTimer,
                                                                 this, std::placeholders::_1));
            }
        }

        void AddressBook::StartSubscriptions() {
            LoadSubscriptions();
            if (m_IsLoaded && m_Subscriptions.empty()) return;

            auto dest = i2p::client::context.GetSharedLocalDestination();
            if (dest) {
                m_SubscriptionsUpdateTimer = new boost::asio::deadline_timer(dest->GetService());
                m_SubscriptionsUpdateTimer->expires_from_now(
                        boost::posix_time::minutes(INITIAL_SUBSCRIPTION_UPDATE_TIMEOUT));
                m_SubscriptionsUpdateTimer->async_wait(std::bind(&AddressBook::HandleSubscriptionsUpdateTimer,
                                                                 this, std::placeholders::_1));
            } else
                LogPrint(eLogError, "Addressbook: Can't start subscriptions: missing shared local destination");
        }

        void AddressBook::StopSubscriptions() {
            if (m_SubscriptionsUpdateTimer)
                m_SubscriptionsUpdateTimer->cancel();
        }

        void AddressBook::HandleSubscriptionsUpdateTimer(const boost::system::error_code &ecode) {
            if (ecode != boost::asio::error::operation_aborted) {
                auto dest = i2p::client::context.GetSharedLocalDestination();
                if (!dest) {
                    LogPrint(eLogWarning, "Addressbook: Missing local destination, skip subscription update");
                    return;
                }
                if (!m_IsDownloading && dest->IsReady()) {
                    if (!m_IsLoaded) {
                        // download it from default subscription
                        LogPrint(eLogInfo, "Addressbook: Trying to download it from default subscription.");
                        std::string defaultSubURL;
                        i2p::config::GetOption("addressbook.defaulturl", defaultSubURL);
                        if (!m_DefaultSubscription)
                            m_DefaultSubscription = std::make_shared<AddressBookSubscription>(*this, defaultSubURL);
                        m_IsDownloading = true;
                        std::thread
                        load_hosts(std::bind(&AddressBookSubscription::CheckUpdates, m_DefaultSubscription));
                        load_hosts.detach(); // TODO: use join
                    } else if (!m_Subscriptions.empty()) {
                        // pick random subscription
                        auto ind = rand() % m_Subscriptions.size();
                        m_IsDownloading = true;
                        std::thread
                        load_hosts(std::bind(&AddressBookSubscription::CheckUpdates, m_Subscriptions[ind]));
                        load_hosts.detach(); // TODO: use join
                    }
                } else {
                    // try it again later
                    m_SubscriptionsUpdateTimer->expires_from_now(
                            boost::posix_time::minutes(INITIAL_SUBSCRIPTION_RETRY_TIMEOUT));
                    m_SubscriptionsUpdateTimer->async_wait(std::bind(&AddressBook::HandleSubscriptionsUpdateTimer,
                                                                     this, std::placeholders::_1));
                }
            }
        }

        void AddressBook::StartLookups() {
            auto dest = i2p::client::context.GetSharedLocalDestination();
            if (dest) {
                auto datagram = dest->GetDatagramDestination();
                if (!datagram)
                    datagram = dest->CreateDatagramDestination();
                datagram->SetReceiver(std::bind(&AddressBook::HandleLookupResponse, this,
                                                std::placeholders::_1, std::placeholders::_2, std::placeholders::_3,
                                                std::placeholders::_4, std::placeholders::_5),
                                      ADDRESS_RESPONSE_DATAGRAM_PORT);
            }
        }

        void AddressBook::StopLookups() {
            auto dest = i2p::client::context.GetSharedLocalDestination();
            if (dest) {
                auto datagram = dest->GetDatagramDestination();
                if (datagram) datagram->ResetReceiver(ADDRESS_RESPONSE_DATAGRAM_PORT);
            }
        }

        void AddressBook::LookupAddress(const std::string &address) {
            std::shared_ptr<const Address> addr;
            auto dot = address.find('.');
            if (dot != std::string::npos)
                addr = FindAddress(address.substr(dot + 1));
            if (!addr || !addr->IsIdentHash()) // TODO:
            {
                LogPrint(eLogError, "Addressbook: Can't find domain for ", address);
                return;
            }

            auto dest = i2p::client::context.GetSharedLocalDestination();
            if (dest) {
                auto datagram = dest->GetDatagramDestination();
                if (datagram) {
                    uint32_t nonce;
                    RAND_bytes((uint8_t * ) & nonce, 4);
                    {
                        std::unique_lock <std::mutex> l(m_LookupsMutex);
                        m_Lookups[nonce] = address;
                    }
                    LogPrint(eLogDebug, "Addressbook: Lookup of ", address, " to ", addr->identHash.ToBase32(),
                             " nonce=", nonce);
                    size_t len = address.length() + 9;
                    uint8_t *buf = new uint8_t[len];
                    memset(buf, 0, 4);
                    htobe32buf(buf + 4, nonce);
                    buf[8] = address.length();
                    memcpy(buf + 9, address.c_str(), address.length());
                    datagram->SendDatagramTo(buf, len, addr->identHash, ADDRESS_RESPONSE_DATAGRAM_PORT,
                                             ADDRESS_RESOLVER_DATAGRAM_PORT);
                    delete[] buf;
                }
            }
        }

        void AddressBook::HandleLookupResponse(const i2p::data::IdentityEx &from, uint16_t fromPort, uint16_t toPort,
                                               const uint8_t *buf, size_t len) {
            if (len < 44) {
                LogPrint(eLogError, "Addressbook: Lookup response is too short ", len);
                return;
            }
            uint32_t nonce = bufbe32toh(buf + 4);
            LogPrint(eLogDebug, "Addressbook: Lookup response received from ", from.GetIdentHash().ToBase32(),
                     " nonce=", nonce);
            std::string address;
            {
                std::unique_lock <std::mutex> l(m_LookupsMutex);
                auto it = m_Lookups.find(nonce);
                if (it != m_Lookups.end()) {
                    address = it->second;
                    m_Lookups.erase(it);
                }
            }
            if (address.length() > 0) {
                // TODO: verify from
                i2p::data::IdentHash hash(buf + 8);
                if (!hash.IsZero())
                    m_Addresses[address] = std::make_shared<Address>(hash);
                else
                    LogPrint(eLogInfo, "AddressBook: Lookup response: ", address, " not found");
            }
        }

        AddressBookSubscription::AddressBookSubscription(AddressBook &book, const std::string &link) :
                m_Book(book), m_Link(link) {
        }

        void AddressBookSubscription::CheckUpdates() {
            i2p::util::SetThreadName("Addressbook");

            bool result = MakeRequest();
            m_Book.DownloadComplete(result, m_Ident, m_Etag, m_LastModified);
        }

        bool AddressBookSubscription::MakeRequest() {
            i2p::http::URL url;
            // must be run in separate thread
            LogPrint(eLogInfo, "Addressbook: Downloading hosts database from ", m_Link);
            if (!url.parse(m_Link)) {
                LogPrint(eLogError, "Addressbook: Failed to parse url: ", m_Link);
                return false;
            }
            auto addr = m_Book.GetAddress(url.host);
            if (!addr || !addr->IsIdentHash()) {
                LogPrint(eLogError, "Addressbook: Can't resolve ", url.host);
                return false;
            } else
                m_Ident = addr->identHash;
            /* this code block still needs some love */
            std::condition_variable newDataReceived;
            std::mutex newDataReceivedMutex;
            auto leaseSet = i2p::client::context.GetSharedLocalDestination()->FindLeaseSet(m_Ident);
            if (!leaseSet) {
                std::unique_lock <std::mutex> l(newDataReceivedMutex);
                i2p::client::context.GetSharedLocalDestination()->RequestDestination(m_Ident,
                                                                                     [&newDataReceived, &leaseSet, &newDataReceivedMutex](
                                                                                             std::shared_ptr <i2p::data::LeaseSet> ls) {
                                                                                         leaseSet = ls;
                                                                                         std::unique_lock <std::mutex> l1(
                                                                                                 newDataReceivedMutex);
                                                                                         newDataReceived.notify_all();
                                                                                     });
                if (newDataReceived.wait_for(l, std::chrono::seconds(SUBSCRIPTION_REQUEST_TIMEOUT)) ==
                    std::cv_status::timeout) {
                    LogPrint(eLogError, "Addressbook: Subscription LeaseSet request timeout expired");
                    i2p::client::context.GetSharedLocalDestination()->CancelDestinationRequest(m_Ident,
                                                                                               false); // don't notify, because we know it already
                    return false;
                }
            }
            if (!leaseSet) {
                /* still no leaseset found */
                LogPrint(eLogError, "Addressbook: LeaseSet for address ", url.host, " not found");
                return false;
            }
            if (m_Etag.empty() && m_LastModified.empty()) {
                m_Book.GetEtag(m_Ident, m_Etag, m_LastModified);
                LogPrint(eLogDebug, "Addressbook: Loaded for ", url.host, ": ETag: ", m_Etag, ", Last-Modified: ",
                         m_LastModified);
            }
            /* save url parts for later use */
            std::string dest_host = url.host;
            int dest_port = url.port ? url.port : 80;
            /* create http request & send it */
            i2p::http::HTTPReq req;
            req.AddHeader("Host", dest_host);
            req.AddHeader("User-Agent", "Wget/1.11.4");
            req.AddHeader("Accept-Encoding", "gzip");
            req.AddHeader("X-Accept-Encoding", "x-i2p-gzip;q=1.0, identity;q=0.5, deflate;q=0, gzip;q=0, *;q=0");
            req.AddHeader("Connection", "close");
            if (!m_Etag.empty())
                req.AddHeader("If-None-Match", m_Etag);
            if (!m_LastModified.empty())
                req.AddHeader("If-Modified-Since", m_LastModified);
            /* convert url to relative */
            url.schema = "";
            url.host = "";
            req.uri = url.to_string();
            req.version = "HTTP/1.1";
            auto stream = i2p::client::context.GetSharedLocalDestination()->CreateStream(leaseSet, dest_port);
            std::string request = req.to_string();
            stream->Send((const uint8_t *) request.data(), request.length());
            /* read response */
            std::string response;
            uint8_t recv_buf[4096];
            bool end = false;
            int numAttempts = 0;
            while (!end) {
                stream->AsyncReceive(boost::asio::buffer(recv_buf, 4096),
                                     [&](const boost::system::error_code &ecode, std::size_t bytes_transferred) {
                                         if (bytes_transferred)
                                             response.append((char *) recv_buf, bytes_transferred);
                                         if (ecode == boost::asio::error::timed_out || !stream->IsOpen())
                                             end = true;
                                         newDataReceived.notify_all();
                                     },
                                     SUBSCRIPTION_REQUEST_TIMEOUT);
                std::unique_lock <std::mutex> l(newDataReceivedMutex);
                // wait 1 more second
                if (newDataReceived.wait_for(l, std::chrono::seconds(SUBSCRIPTION_REQUEST_TIMEOUT + 1)) ==
                    std::cv_status::timeout) {
                    LogPrint(eLogError, "Addressbook: Subscriptions request timeout expired");
                    numAttempts++;
                    if (numAttempts > 5) end = true;
                }
            }
            // process remaining buffer
            while (size_t len = stream->ReadSome(recv_buf, sizeof(recv_buf)))
                response.append((char *) recv_buf, len);
            /* parse response */
            i2p::http::HTTPRes res;
            int res_head_len = res.parse(response);
            if (res_head_len < 0) {
                LogPrint(eLogError, "Addressbook: Can't parse http response from ", dest_host);
                return false;
            }
            if (res_head_len == 0) {
                LogPrint(eLogError, "Addressbook: Incomplete http response from ", dest_host,
                         ", interrupted by timeout");
                return false;
            }
            /* assert: res_head_len > 0 */
            response.erase(0, res_head_len);
            if (res.code == 304) {
                LogPrint(eLogInfo, "Addressbook: No updates from ", dest_host, ", code 304");
                return false;
            }
            if (res.code != 200) {
                LogPrint(eLogWarning, "Adressbook: Can't get updates from ", dest_host, ", response code ", res.code);
                return false;
            }
            int len = res.content_length();
            if (response.empty()) {
                LogPrint(eLogError, "Addressbook: Empty response from ", dest_host, ", expected ", len, " bytes");
                return false;
            }
            if (!res.is_gzipped() && len > 0 && len != (int) response.length()) {
                LogPrint(eLogError, "Addressbook: Response size mismatch, expected: ", len, ", got: ",
                         response.length(), "bytes");
                return false;
            }
            /* assert: res.code == 200 */
            auto it = res.headers.find("ETag");
            if (it != res.headers.end()) m_Etag = it->second;
            it = res.headers.find("Last-Modified");
            if (it != res.headers.end()) m_LastModified = it->second;
            if (res.is_chunked()) {
                std::stringstream in(response), out;
                i2p::http::MergeChunkedResponse(in, out);
                response = out.str();
            }
            if (res.is_gzipped()) {
                std::stringstream out;
                i2p::data::GzipInflator inflator;
                inflator.Inflate((const uint8_t *) response.data(), response.length(), out);
                if (out.fail()) {
                    LogPrint(eLogError, "Addressbook: Can't gunzip http response");
                    return false;
                }
                response = out.str();
            }
            std::stringstream ss(response);
            LogPrint(eLogInfo, "Addressbook: Got update from ", dest_host);
            m_Book.LoadHostsFromStream(ss, true);
            return true;
        }

        AddressResolver::AddressResolver(std::shared_ptr <ClientDestination> destination) :
                m_LocalDestination(destination) {
            if (m_LocalDestination) {
                auto datagram = m_LocalDestination->GetDatagramDestination();
                if (!datagram)
                    datagram = m_LocalDestination->CreateDatagramDestination();
                datagram->SetReceiver(std::bind(&AddressResolver::HandleRequest, this,
                                                std::placeholders::_1, std::placeholders::_2, std::placeholders::_3,
                                                std::placeholders::_4, std::placeholders::_5),
                                      ADDRESS_RESOLVER_DATAGRAM_PORT);
            }
        }

        AddressResolver::~AddressResolver() {
            if (m_LocalDestination) {
                auto datagram = m_LocalDestination->GetDatagramDestination();
                if (datagram)
                    datagram->ResetReceiver(ADDRESS_RESOLVER_DATAGRAM_PORT);
            }
        }

        void AddressResolver::HandleRequest(const i2p::data::IdentityEx &from, uint16_t fromPort, uint16_t toPort,
                                            const uint8_t *buf, size_t len) {
            if (len < 9 || len < buf[8] + 9U) {
                LogPrint(eLogError, "Addressbook: Address request is too short ", len);
                return;
            }
            // read requested address
            uint8_t l = buf[8];
            char address[255];
            memcpy(address, buf + 9, l);
            address[l] = 0;
            LogPrint(eLogDebug, "Addressbook: Address request ", address);
            // send response
            uint8_t response[44];
            memset(response, 0, 4); // reserved
            memcpy(response + 4, buf + 4, 4); // nonce
            auto it = m_LocalAddresses.find(address); // address lookup
            if (it != m_LocalAddresses.end())
                memcpy(response + 8, it->second, 32); // ident
            else
                memset(response + 8, 0, 32); // not found
            memset(response + 40, 0, 4); // set expiration time to zero
            m_LocalDestination->GetDatagramDestination()->SendDatagramTo(response, 44, from.GetIdentHash(), toPort,
                                                                         fromPort);
        }

        void AddressResolver::AddAddress(const std::string &name, const i2p::data::IdentHash &ident) {
            m_LocalAddresses[name] = ident;
        }

    }
}