ban.cpp

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/*
    Copyright (C) 2008 - 2024
    by Pauli Nieminen <paniemin@cc.hut.fi>
    Part of the Battle for Wesnoth Project https://www.wesnoth.org/
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.
    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY.
 
    See the COPYING file for more details.
*/
 
#include "config.hpp"
#include "filesystem.hpp"
#include "lexical_cast.hpp"
#include "log.hpp"
#include "serialization/binary_or_text.hpp"
#include "serialization/chrono.hpp"
#include "serialization/parser.hpp"
#include "serialization/string_utils.hpp"
#include "serialization/unicode.hpp"
#include "utils/general.hpp"
 
#include "server/wesnothd/ban.hpp"
 
#include <functional>
 
namespace wesnothd
{
static lg::log_domain log_server("server");
#define ERR_SERVER LOG_STREAM(err, log_server)
#define LOG_SERVER LOG_STREAM(info, log_server)
#define DBG_SERVER LOG_STREAM(debug, log_server)
 
std::ostream& operator<<(std::ostream& o, const banned& n)
{
    return o << "IP: " << n.get_ip() <<
        (n.get_nick().empty() ? "" : "  nick: " + n.get_nick()) <<
        "  reason: '" << n.get_reason() << "'"
        "  start_time: " << n.get_human_start_time() <<
        "  end_time: " << n.get_human_end_time() <<
        "  issuer: " <<  n.get_who_banned();
}
 
bool banned_compare::operator()(const banned_ptr& a, const banned_ptr& b) const
{
    return (*a) > (*b);
}
 
banned_compare_subnet::compare_fn banned_compare_subnet::active_ = &banned_compare_subnet::less;
 
bool banned_compare_subnet::operator()(const banned_ptr& a, const banned_ptr& b) const
{
    return (this->*(active_))(a,b);
}
 
bool banned_compare_subnet::less(const banned_ptr& a, const banned_ptr& b) const
{
    return a->get_int_ip() < b->get_int_ip();
}
 
const std::string banned::who_banned_default_ = "system";
 
banned::banned(const std::string& ip)
    : ip_(0)
    , mask_(0)
    , ip_text_()
    , end_time_()
    , start_time_()
    , reason_()
    , who_banned_(who_banned_default_)
    , group_()
    , nick_()
{
    ip_mask pair = parse_ip(ip);
    ip_ = pair.first;
    mask_ = 0xFFFFFFFF;
}
 
banned::banned(const std::string& ip,
        const utils::optional<std::chrono::system_clock::time_point>& end_time,
        const std::string& reason,
        const std::string& who_banned,
        const std::string& group,
        const std::string& nick)
    : ip_(0)
    , mask_(0)
    , ip_text_(ip)
    , end_time_(end_time)
    , start_time_(std::chrono::system_clock::now())
    , reason_(reason)
    , who_banned_(who_banned)
    , group_(group)
    , nick_(nick)
{
    ip_mask pair = parse_ip(ip_text_);
    ip_ = pair.first;
    mask_ = pair.second;
}
 
banned::banned(const config& cfg)
    : ip_(0)
    , mask_(0)
    , ip_text_()
    , end_time_()
    , start_time_()
    , reason_()
    , who_banned_(who_banned_default_)
    , group_()
    , nick_()
{
    read(cfg);
}
 
ip_mask parse_ip(const std::string& ip)
{
    // We use bit operations to construct the integer
    // ip_mask is a pair: first is ip and second is mask
    ip_mask ret;
    ret.first = 0;
    ret.second = 0;
    std::vector<std::string> split_ip = utils::split(ip, '.');
    if (split_ip.size() > 4) throw banned::error("Malformed ip address: " + ip);
 
    unsigned int shift = 4*8; // start shifting from the highest byte
    //unsigned int mask = 0xFF000000;
    const unsigned int complete_part_mask = 0xFF;
    auto part = split_ip.begin();
    bool wildcard = false;
    do {
        shift -= 8;
        //mask >>= 8;
        if(part == split_ip.end()) {
            if(!wildcard)
                throw banned::error("Malformed ip address: '" + ip + "'");
            // Adding 0 to ip and mask is nop
            // we can then break out of loop
            break;
        } else {
            if(*part == "*") {
                wildcard = true;
                // Adding 0 to ip and mask is nop
            } else {
                // wildcard = false;
                unsigned int part_ip = lexical_cast_default<unsigned int>(*part, complete_part_mask + 1);
                if(part_ip > complete_part_mask) {
                    throw banned::error("Malformed ip address: '" + ip + "'");
                }
 
                ret.first |= (part_ip << shift);
                ret.second |= (complete_part_mask << shift);
            }
        }
        ++part;
    } while(shift);
 
    return ret;
}
 
void banned::read(const config& cfg)
{
    {
        // parse ip and mask
        ip_text_ = cfg["ip"].str();
        ip_mask pair = parse_ip(ip_text_);
        ip_ = pair.first;
        mask_ = pair.second;
    }
 
    nick_ = cfg["nick"].str();
 
    if(cfg.has_attribute("end_time")) {
        end_time_ = chrono::parse_timestamp(cfg["end_time"]);
    }
 
    if(cfg.has_attribute("start_time")) {
        start_time_ = chrono::parse_timestamp(cfg["start_time"]);
    }
 
    reason_ = cfg["reason"].str();
 
    // only overwrite defaults if exists
    if(cfg.has_attribute("who_banned")) {
        who_banned_ = cfg["who_banned"].str();
    }
 
    if(cfg.has_attribute("group")) {
        group_ = cfg["group"].str();
    }
}
 
void banned::write(config& cfg) const
{
    cfg["ip"] = get_ip();
    cfg["nick"] = get_nick();
 
    if(end_time_) {
        cfg["end_time"] = chrono::serialize_timestamp(*end_time_);
    }
 
    if(start_time_) {
        cfg["start_time"] = chrono::serialize_timestamp(*start_time_);
    }
 
    cfg["reason"] = reason_;
 
    if(who_banned_ != who_banned_default_) {
        cfg["who_banned"] = who_banned_;
    }
 
    if(!group_.empty()) {
        cfg["group"] = group_;
    }
}
 
std::string banned::get_human_start_time() const
{
    if(start_time_) {
        return chrono::format_local_timestamp(*start_time_);
    } else {
        return "unknown";
    }
}
 
std::string banned::get_human_end_time() const
{
    if(end_time_) {
        return chrono::format_local_timestamp(*end_time_);
    } else {
        return "permanent";
    }
}
 
std::string banned::get_human_time_span() const
{
    if(!end_time_) {
        return "permanent";
    }
 
    auto remaining = *end_time_ - std::chrono::system_clock::now();
    return lg::format_timespan(std::chrono::duration_cast<std::chrono::seconds>(remaining));
}
 
bool banned::operator>(const banned& b) const
{
    static constexpr std::chrono::system_clock::time_point epoch;
    return end_time_.value_or(epoch) > b.get_end_time().value_or(epoch);
}
 
unsigned int banned::get_mask_ip(unsigned int mask) const
{
    return ip_ & mask & mask_;
}
 
bool banned::match_ip(const ip_mask& pair) const
{
    return (ip_ & mask_) == (pair.first & mask_);
}
 
// Unlike match_ip this function takes both masks into account.
bool banned::match_ipmask(const ip_mask& pair) const
{
    return (ip_ & mask_ & pair.second) == (pair.first & pair.second & mask_);
}
 
void ban_manager::read()
{
    if(filename_.empty() || !filesystem::file_exists(filename_)) {
        return;
    }
 
    LOG_SERVER << "Reading bans from " <<  filename_;
    config cfg;
    dirty_ = false;
    filesystem::scoped_istream ban_file = filesystem::istream_file(filename_);
    read_gz(cfg, *ban_file);
 
    for(const config& b : cfg.child_range("ban")) {
        try {
            auto new_ban = std::make_shared<banned>(b);
            assert(bans_.insert(new_ban).second);
 
            if (new_ban->get_end_time())
                time_queue_.push(new_ban);
        } catch(const banned::error& e) {
            ERR_SERVER << e.message << " while reading bans";
        }
    }
 
    // load deleted too
    if(auto cfg_del = cfg.optional_child("deleted")) {
        for(const config& b : cfg_del->child_range("ban")) {
            try {
                auto new_ban = std::make_shared<banned>(b);
                deleted_bans_.push_back(new_ban);
            } catch(const banned::error& e) {
                ERR_SERVER << e.message << " while reading deleted bans";
            }
        }
    }
}
 
void ban_manager::write()
{
    if(filename_.empty() || !dirty_) {
        return;
    }
 
    LOG_SERVER << "Writing bans to " << filename_;
    dirty_ = false;
 
    config cfg;
    for(const auto& b : bans_) {
        config& child = cfg.add_child("ban");
        b->write(child);
    }
 
    config& deleted = cfg.add_child("deleted");
    for(const auto& db : deleted_bans_) {
        config& child = deleted.add_child("ban");
        db->write(child);
    }
 
    filesystem::scoped_ostream ban_file = filesystem::ostream_file(filename_);
    config_writer writer(*ban_file, true);
    writer.write(cfg);
}
 
std::pair<bool, utils::optional<std::chrono::system_clock::time_point>> ban_manager::parse_time(
    const std::string& duration, std::chrono::system_clock::time_point start_time) const
{
    if(duration.substr(0, 4) == "TIME") {
        auto as_time_t = std::chrono::system_clock::to_time_t(start_time);
        std::tm* loc = std::localtime(&as_time_t);
 
        std::size_t number = 0;
        for(auto i = duration.begin() + 4; i != duration.end(); ++i) {
            if(is_digit(*i)) {
                number = number * 10 + to_digit(*i);
            } else {
                switch(*i) {
                case 'Y':
                    loc->tm_year = number;
                    break;
                case 'M':
                    loc->tm_mon = number;
                    break;
                case 'D':
                    loc->tm_mday = number;
                    break;
                case 'h':
                    loc->tm_hour = number;
                    break;
                case 'm':
                    loc->tm_min = number;
                    break;
                case 's':
                    loc->tm_sec = number;
                    break;
                default:
                    LOG_SERVER << "Invalid time modifier given: '" << *i << "'.";
                    break;
                }
                number = 0;
            }
        }
        return { true, std::chrono::system_clock::from_time_t(std::mktime(loc)) };
    }
 
    std::string dur_lower;
    try {
        dur_lower = utf8::lowercase(duration);
    } catch(const utf8::invalid_utf8_exception& e) {
        ERR_SERVER << "While parsing ban command duration string, caught an invalid utf8 exception: " << e.what();
        return { false, utils::nullopt };
    }
 
    if(dur_lower == "permanent" || duration == "0") {
        return { true, utils::nullopt };
    } else if(const auto time_itor = ban_times_.find(duration); time_itor != ban_times_.end()) {
        return { true, start_time + time_itor->second };
    } else {
        std::string::const_iterator i = duration.begin();
        int number = -1;
        for (std::string::const_iterator d_end = duration.end(); i != d_end; ++i) {
            if (is_digit(*i))
            {
                if (number == -1) number = 0;
                number = number * 10 + to_digit(*i);
            } else {
                if (number == -1) number = 1;
                switch(*i)
                {
                    case 'Y':
                    case 'y':
                        if (++i != d_end && tolower(*i) == 'e'
                        &&  ++i != d_end && tolower(*i) == 'a'
                        &&  ++i != d_end && tolower(*i) == 'r'
                        &&  ++i != d_end && tolower(*i) == 's') {
                        } else --i;
                        start_time += chrono::years{number};
                        break;
                    case 'M':
                        if (++i != d_end && tolower(*i) == 'i') {
                            if (++i != d_end && tolower(*i) == 'n'
                            &&  ++i != d_end && tolower(*i) == 'u'
                            &&  ++i != d_end && tolower(*i) == 't'
                            &&  ++i != d_end && tolower(*i) == 'e'
                            &&  ++i != d_end && tolower(*i) == 's') {
                            } else --i;
                            start_time += std::chrono::minutes{number};
                            break;
                        }
                        --i;
                        if (++i != d_end && tolower(*i) == 'o'
                        &&  ++i != d_end && tolower(*i) == 'n'
                        &&  ++i != d_end && tolower(*i) == 't'
                        &&  ++i != d_end && tolower(*i) == 'h'
                        &&  ++i != d_end && tolower(*i) == 's') {
                        } else --i;
                        start_time += chrono::months{number};
                        break;
                    case 'D':
                    case 'd':
                        if (++i != d_end && tolower(*i) == 'a'
                        &&  ++i != d_end && tolower(*i) == 'y'
                        &&  ++i != d_end && tolower(*i) == 's') {
                        } else --i;
                        start_time += chrono::days{number};
                        break;
                    case 'H':
                    case 'h':
                        if (++i != d_end && tolower(*i) == 'o'
                        &&  ++i != d_end && tolower(*i) == 'u'
                        &&  ++i != d_end && tolower(*i) == 'r'
                        &&  ++i != d_end && tolower(*i) == 's') {
                        } else --i;
                        start_time += std::chrono::hours{number};
                        break;
                    case 'm':
                        if (++i != d_end && tolower(*i) == 'o') {
                            if (++i != d_end && tolower(*i) == 'n'
                            &&  ++i != d_end && tolower(*i) == 't'
                            &&  ++i != d_end && tolower(*i) == 'h'
                            &&  ++i != d_end && tolower(*i) == 's') {
                            } else --i;
                            start_time += chrono::months{number};
                            break;
                        }
                        --i;
                        if (++i != d_end && tolower(*i) == 'i'
                        &&  ++i != d_end && tolower(*i) == 'n'
                        &&  ++i != d_end && tolower(*i) == 'u'
                        &&  ++i != d_end && tolower(*i) == 't'
                        &&  ++i != d_end && tolower(*i) == 'e'
                        &&  ++i != d_end && tolower(*i) == 's') {
                        } else --i;
                        start_time += std::chrono::minutes{number};
                        break;
                    case 'S':
                    case 's':
                        if (++i != d_end && tolower(*i) == 'e'
                        &&  ++i != d_end && tolower(*i) == 'c'
                        &&  ++i != d_end && tolower(*i) == 'o'
                        &&  ++i != d_end && tolower(*i) == 'n'
                        &&  ++i != d_end && tolower(*i) == 'd'
                        &&  ++i != d_end && tolower(*i) == 's') {
                        } else --i;
                        start_time += std::chrono::seconds{number};
                        break;
                    default:
                        return { false, utils::nullopt };
                        break;
                }
                number = -1;
            }
        }
 
        if(is_digit(*--i)) {
            start_time += std::chrono::minutes{number}; // default to minutes
        }
 
        return { true, start_time };
    }
}
 
std::string ban_manager::ban(const std::string& ip,
    const utils::optional<std::chrono::system_clock::time_point>& end_time,
    const std::string& reason,
    const std::string& who_banned,
    const std::string& group,
    const std::string& nick)
{
    std::ostringstream ret;
    try {
        ban_set::iterator ban;
        if((ban = bans_.find(std::make_shared<banned>(ip))) != bans_.end()) {
            // Already exsiting ban for ip. We have to first remove it
            ret << "Overwriting ban: " << (**ban) << "\n";
            bans_.erase(ban);
        }
    } catch(const banned::error& e) {
        ERR_SERVER << e.message << " while creating dummy ban for finding existing ban";
        return e.message;
    }
 
    try {
        auto new_ban = std::make_shared<banned>(ip, end_time, reason, who_banned, group, nick);
        bans_.insert(new_ban);
        if(end_time) {
            time_queue_.push(new_ban);
        }
        ret << *new_ban;
    } catch(const banned::error& e) {
        ERR_SERVER << e.message << " while banning";
        return e.message;
    }
 
    dirty_ = true;
    write();
    return ret.str();
}
 
void ban_manager::unban(std::ostringstream& os, const std::string& ip, bool immediate_write)
{
    ban_set::iterator ban;
    try {
        ban = bans_.find(std::make_shared<banned>(ip));
    } catch (const banned::error& e) {
        ERR_SERVER << e.message;
        os << e.message;
        return;
    }
 
    if(ban == bans_.end()) {
        os << "There is no ban on '" << ip << "'.";
        return;
    }
 
    // keep ban entry still in memory
    os << "Ban on '" << **ban << "' removed.";
    // group bans don't get saved
    if ((*ban)->get_group().empty()) deleted_bans_.push_back(*ban);
    bans_.erase(ban);
    dirty_ = true;
    if(immediate_write) {
        write();
    }
}
 
void ban_manager::unban_group(std::ostringstream& os, const std::string& group)
{
    ban_set temp;
    std::insert_iterator<ban_set> temp_inserter(temp, temp.begin());
    std::remove_copy_if(bans_.begin(), bans_.end(), temp_inserter, [&group](const banned_ptr& p) { return p->match_group(group); });
 
    os << "Removed " << (bans_.size() - temp.size()) << " bans";
    bans_.swap(temp);
    dirty_ = true;
    write();
}
 
void ban_manager::check_ban_times(const std::chrono::system_clock::time_point& time_now)
{
    while(!time_queue_.empty()) {
        banned_ptr ban = time_queue_.top();
        const auto& end_time = ban->get_end_time();
 
        if(!end_time || *end_time > time_now) {
            // No bans going to expire
            DBG_SERVER
                << "Ban on " << ban->get_ip() << " not removed."
                << " time: "     <<             chrono::format_local_timestamp(time_now)
                << " end_time: " << (end_time ? chrono::format_local_timestamp(*end_time) : "none");
            break;
        }
 
        // This ban is going to expire so delete it.
        LOG_SERVER
            << "Removing ban on " << ban->get_ip() << "."
            << " time: "     << chrono::format_local_timestamp(time_now)
            << " end_time: " << chrono::format_local_timestamp(*end_time);
        std::ostringstream os;
        unban(os, ban->get_ip(), false);
        time_queue_.pop();
    }
 
    // Save bans if there is any new ones
    write();
}
 
void ban_manager::list_deleted_bans(std::ostringstream& out, const std::string& mask) const
{
    if(deleted_bans_.empty()) {
        out << "No removed bans found.";
        return;
    }
 
    ip_mask pair;
    try {
        pair = parse_ip(mask);
    } catch(const banned::error& e) {
        out << "parse error: " << e.message;
        return;
    }
 
    out << "DELETED BANS LIST";
    for(deleted_ban_list::const_iterator i = deleted_bans_.begin(); i != deleted_bans_.end(); ++i) {
        if((*i)->match_ipmask(pair)) {
            out << "\n" << (**i);
        }
    }
}
 
void ban_manager::list_bans(std::ostringstream& out, const std::string& mask)
{
    expire_bans();
    if(bans_.empty()) {
        out << "No bans set.";
        return;
    }
 
    ip_mask pair;
    try {
        pair = parse_ip(mask);
    } catch(const banned::error& e) {
        out << "parse error: " << e.message;
        return;
    }
 
    out << "BAN LIST";
    std::set<std::string> groups;
 
    for(const auto& b : bans_) {
        if(b->get_group().empty()) {
            if(b->match_ipmask(pair)) {
                out << "\n" << *b;
            }
        } else {
            groups.insert(b->get_group());
        }
    }
 
    // Don't list ban groups when looking for specific bans.
    if(!groups.empty() && mask == "*") {
        out << "\nban groups: ";
 
        out << *groups.begin();
        std::ostream& (*fn)(std::ostream&, const std::string&) = &std::operator<<;
        std::for_each(++groups.begin(), groups.end(),
            std::bind(fn, std::bind(fn, std::ref(out), std::string(", ")), std::placeholders::_1));
    }
}
 
std::string ban_manager::is_ip_banned(const std::string& ip)
{
    expire_bans();
    ip_mask pair;
    try {
        pair = parse_ip(ip);
    } catch (const banned::error&) {
        return "";
    }
 
    auto ban = std::find_if(bans_.begin(), bans_.end(), [pair](const banned_ptr& p) { return p->match_ip(pair); });
    if (ban == bans_.end()) return "";
    const std::string& nick = (*ban)->get_nick();
    return (*ban)->get_reason() + (nick.empty() ? "" : " (" + nick + ")") + " (Remaining ban duration: " + (*ban)->get_human_time_span() + ")";
}
 
void ban_manager::init_ban_help()
{
    ban_help_ = "ban <mask> <time> <reason>\n"
            "The time format is: %d[%s[%d[%s[...]]]] where %s is a time"
            " modifier: s or S (seconds), m (minutes), h or H (hours), d"
            " or D (days), M (months) or y or Y (years) and %d is a number.\n"
            "Permanent bans can be set with 'permanent' or '0' as the time"
            " argument.\n";
    auto itor = ban_times_.begin();
    if(itor != ban_times_.end()) {
        ban_help_ += "You can also use " + itor->first;
        ++itor;
    }
    for(; itor != ban_times_.end(); ++itor) {
        ban_help_ += std::string(", ") + itor->first;
    }
    if(!ban_times_.empty()) {
        ban_help_ += " for standard ban times. (not combinable)\n";
    }
    ban_help_ += "ban 127.0.0.1 2h20m flooded lobby\n"
            "kban suokko 5D flooded again\n"
            "kban suokko Y One year ban for constant flooding";
}
 
void ban_manager::load_config(const config& cfg)
{
    ban_times_.clear();
    for(const config& bt : cfg.child_range("ban_time")) {
        // Use the zero time point so we can easily convert the end time point to a duration
        auto [success, end_time] = parse_time(bt["time"], {});
 
        if(success) {
            auto duration = end_time.value_or(decltype(end_time)::value_type{}).time_since_epoch();
            ban_times_.emplace(bt["name"], std::chrono::duration_cast<std::chrono::seconds>(duration));
        }
    }
 
    init_ban_help();
    if(filename_ != cfg["ban_save_file"]) {
        dirty_ = true;
        filename_ = cfg["ban_save_file"].str();
    }
}
 
ban_manager::~ban_manager()
{
    try {
        write();
    } catch(...) {
        DBG_SERVER << "Caught exception in ban_manager destructor: " << utils::get_unknown_exception_type();
    }
}
 
ban_manager::ban_manager()
    : bans_()
    , deleted_bans_()
    , time_queue_()
    , ban_times_()
    , ban_help_()
    , filename_()
    , dirty_(false)
{
    init_ban_help();
}
 
} // namespace wesnothd