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/*
* Copyright (C) 2008 Big Muscle, http://strongdc.sourceforge.net/
*
* 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; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
#include "stdafx.h"
#include "Utils.h"
#include "Constants.h"
#include "dcpp/AdcCommand.h"
#include "dcpp/CID.h"
#include "dcpp/MerkleTree.h"
#include "dcpp/TimerManager.h"
#include "dcpp/SettingsManager.h"
namespace dht
{
CriticalSection Utils::cs;
std::unordered_map< string, std::unordered_multiset<uint32_t> > Utils::receivedPackets;
std::list<Utils::OutPacket> Utils::sentPackets;
CID Utils::getDistance(const CID& cid1, const CID& cid2)
{
uint8_t distance[CID::SIZE];
for(int i = 0; i < CID::SIZE; ++i)
{
distance[i] = cid1.data()[i] ^ cid2.data()[i];
}
return CID(distance);
}
/*
* Detect whether it is correct to use IP:port in DHT network
*/
bool Utils::isGoodIPPort(const string& ip, const string& port)
{
// don't allow empty IP and port lower than 1024
// ports below 1024 are known service ports, so they shouldn't be used for DHT else it could be used for attacks
if(ip.empty() || Util::toInt(port) < 1024)
return false;
// don't allow private IPs
if(Util::isPrivateIp(ip))
return false;
return true;
}
/*
* General flooding protection
*/
bool Utils::checkFlood(const string& ip, const AdcCommand& cmd)
{
// ignore empty commands
if(cmd.getParameters().empty())
return false;
// there maximum allowed request packets from one IP per minute
// response packets are allowed only if request has been sent to the IP address
size_t maxAllowedPacketsPerMinute = 0;
uint32_t requestCmd = AdcCommand::CMD_SCH;
switch(cmd.getCommand())
{
// request packets
case AdcCommand::CMD_SCH: maxAllowedPacketsPerMinute = 20; break;
case AdcCommand::CMD_PUB: maxAllowedPacketsPerMinute = 10; break;
case AdcCommand::CMD_INF: maxAllowedPacketsPerMinute = 3; break;
case AdcCommand::CMD_CTM: maxAllowedPacketsPerMinute = 2; break;
case AdcCommand::CMD_RCM: maxAllowedPacketsPerMinute = 2; break;
case AdcCommand::CMD_GET: maxAllowedPacketsPerMinute = 2; break;
case AdcCommand::CMD_PSR: maxAllowedPacketsPerMinute = 3; break;
// response packets
case AdcCommand::CMD_STA:
return true; // STA can be response for more commands, but since it is for informative purposes only, there shouldn't be no way to abuse it
case AdcCommand::CMD_SND: requestCmd = AdcCommand::CMD_GET;
case AdcCommand::CMD_RES: // default value of requestCmd
Lock l(cs);
for(std::list<OutPacket>::iterator i = sentPackets.begin(); i != sentPackets.end(); ++i)
{
if(i->cmd == requestCmd && i->ip == ip)
{
sentPackets.erase(i);
return true;
}
}
dcdebug("Received unwanted response from %s. Packet dropped.\n", ip.c_str());
return false;
}
Lock l(cs);
std::unordered_multiset<uint32_t>& packetsPerIp = receivedPackets[ip];
packetsPerIp.insert(cmd.getCommand());
if(packetsPerIp.count(cmd.getCommand()) > maxAllowedPacketsPerMinute)
{
dcdebug("Request flood detected (%li) from %s. Packet dropped.\n", (long int)packetsPerIp.count(cmd.getCommand()), ip.c_str());
return false;
}
return true;
}
/*
* Removes tracked packets. Called once a minute.
*/
void Utils::cleanFlood()
{
Lock l(cs);
receivedPackets.clear();
}
/*
* Stores outgoing request to avoid receiving invalid responses
*/
void Utils::trackOutgoingPacket(const string& ip, const AdcCommand& cmd)
{
Lock l(cs);
uint64_t now = GET_TICK();
switch(cmd.getCommand())
{
// request packets
case AdcCommand::CMD_SCH:
case AdcCommand::CMD_PUB:
case AdcCommand::CMD_INF:
case AdcCommand::CMD_CTM:
case AdcCommand::CMD_GET:
case AdcCommand::CMD_PSR:
OutPacket p = { ip, now, cmd.getCommand() };
sentPackets.push_back(p);
break;
}
// clean up old items
// list is sorted by time, so the first unmatched item can break the loop
while(!sentPackets.empty())
{
uint64_t diff = now - sentPackets.front().time;
if(diff >= TIME_FOR_RESPONSE)
sentPackets.pop_front();
else
break;
}
}
/*
* Generates UDP key for specified IP address
*/
CID Utils::getUdpKey(const string& targetIp)
{
CID myUdpKey = CID(SETTING(DHT_KEY));
TigerTree th;
th.update(myUdpKey.data(), sizeof(CID));
th.update(targetIp.c_str(), targetIp.size());
return CID(th.finalize());
}
bool IsInvalid(char ch) { return ch == '\r' || ch == '\n' || ch == '\t'; }
const string& Utils::compressXML(string& xml)
{
xml.erase(std::remove_if(xml.begin(), xml.end(), IsInvalid), xml.end());
return xml;
}
} // namespace dht
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