/*
* InspIRCd -- Internet Relay Chat Daemon
*
* Copyright (C) 2018-2020 Matt Schatz <genius3000@g3k.solutions>
* Copyright (C) 2018-2019 linuxdaemon <linuxdaemon.irc@gmail.com>
* Copyright (C) 2013, 2017-2021 Sadie Powell <sadie@witchery.services>
* Copyright (C) 2013, 2015-2016 Adam <Adam@anope.org>
* Copyright (C) 2012-2016 Attila Molnar <attilamolnar@hush.com>
* Copyright (C) 2012, 2018 Robby <robby@chatbelgie.be>
* Copyright (C) 2009-2010 Daniel De Graaf <danieldg@inspircd.org>
* Copyright (C) 2007, 2010 Craig Edwards <brain@inspircd.org>
* Copyright (C) 2007 Dennis Friis <peavey@inspircd.org>
* Copyright (C) 2006-2009 Robin Burchell <robin+git@viroteck.net>
*
* This file is part of InspIRCd. InspIRCd 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, version 2.
*
* 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 <http://www.gnu.org/licenses/>.
*/
#include "inspircd.h"
#include "xline.h"
#include "modules/dns.h"
#include "modules/stats.h"
class DNSBLEntry final
{
public:
enum class Action : uint8_t
{
// G-line users who's IP address is in the DNSBL.
GLINE,
// Kill users who's IP address is in the DNSBL.
KILL,
// K-line users who's IP address is in the DNSBL.
KLINE,
// Mark users who's IP address is in the DNSBL.
MARK,
// Z-line users who's IP address is in the DNSBL.
ZLINE,
};
enum class Type : uint8_t
{
// DNSBL results will be compared against the specified bit mask.
BITMASK,
// DNSBL results will be compared against a numeric range of values.
RECORD,
};
// The action to take against users who's IP address is in this DNSBL.
Action action;
// A bitmask of DNSBL result types to match against.
unsigned int bitmask;
// The domain name of this DNSBL.
std::string domain;
// If action is set to mark then a new username (ident) to set on users who's IP address is in this DNSBL.
std::string markhost;
// If action is set to mark then a new hostname to set on users who's IP address is in this DNSBL.
std::string markident;
// The human readable name of this DNSBL.
std::string name;
// A range of DNSBL result types to match against.
std::bitset<UCHAR_MAX + 1> records;
// The message to send to users who's IP address is in a DNSBL.
std::string reason;
// The number of seconds to wait for a DNSBL request before assuming it has failed.
unsigned int timeout;
// The type of result that this DNSBL will provide.
Type type;
// The number of errors which have occurred when querying this DNSBL.
unsigned long stats_errors = 0;
// The number of hits which have occurred when querying this DNSBL.
unsigned long stats_hits = 0;
// The number of misses which have occurred when querying this DNSBL.
unsigned long stats_misses = 0;
// If action is set to gline, kline, or zline then the duration for an X-line to last for.
unsigned long xlineduration;
DNSBLEntry(std::shared_ptr<ConfigTag> tag)
{
name = tag->getString("name");
if (name.empty())
throw ModuleException("<dnsbl:name> can not be empty at " + tag->source.str());
domain = tag->getString("domain");
if (domain.empty())
throw ModuleException("<dnsbl:domain> can not be empty at " + tag->source.str());
action = tag->getEnum("action", Action::KILL, {
{ "gline", Action::GLINE },
{ "kill", Action::KILL },
{ "kline", Action::KLINE },
{ "mark", Action::MARK },
{ "zline", Action::ZLINE },
});
const std::string typestr = tag->getString("type");
if (stdalgo::string::equalsci(typestr, "bitmask"))
{
type = Type::BITMASK;
bitmask = static_cast<unsigned int>(tag->getUInt("bitmask", 0, 0, UINT_MAX));
records = 0;
}
else if (stdalgo::string::equalsci(typestr, "record"))
{
type = Type::RECORD;
irc::portparser recordrange(tag->getString("records"), false);
for (long record = 0; (record = recordrange.GetToken()); )
{
if (record < 0 || record > UCHAR_MAX)
throw ModuleException("<dnsbl:records> can only hold records between 0 and 255 at " + tag->source.str());
records.set(record);
}
}
else
{
throw ModuleException(typestr + " is an invalid value for <dnsbl:type>; acceptable values are 'bitmask' or 'records' at "
+ tag->source.str());
}
reason = tag->getString("reason", "Your IP (%ip%) has been blacklisted by a DNSBL.", 1, ServerInstance->Config->Limits.MaxLine);
timeout = static_cast<unsigned int>(tag->getDuration("timeout", 0, 1, 60));
markident = tag->getString("ident");
markhost = tag->getString("host");
xlineduration = tag->getDuration("duration", 60*60, 1);
}
};
class DNSBLResolver : public DNS::Request
{
private:
irc::sockets::sockaddrs theirsa;
std::string theiruid;
StringExtItem& nameExt;
IntExtItem& countExt;
std::shared_ptr<DNSBLEntry> ConfEntry;
public:
DNSBLResolver(DNS::Manager *mgr, Module *me, StringExtItem& match, IntExtItem& ctr, const std::string &hostname, LocalUser* u, std::shared_ptr<DNSBLEntry> conf)
: DNS::Request(mgr, me, hostname, DNS::QUERY_A, true, conf->timeout)
, theirsa(u->client_sa)
, theiruid(u->uuid)
, nameExt(match)
, countExt(ctr)
, ConfEntry(conf)
{
}
/* Note: This may be called multiple times for multiple A record results */
void OnLookupComplete(const DNS::Query *r) override
{
/* Check the user still exists */
LocalUser* them = IS_LOCAL(ServerInstance->Users.FindUUID(theiruid));
if (!them || them->client_sa != theirsa)
{
ConfEntry->stats_misses++;
return;
}
intptr_t i = countExt.Get(them);
if (i)
countExt.Set(them, i - 1);
// The DNSBL reply must contain an A result.
const DNS::ResourceRecord* const ans_record = r->FindAnswerOfType(DNS::QUERY_A);
if (!ans_record)
{
ConfEntry->stats_errors++;
ServerInstance->SNO.WriteGlobalSno('d', "%s returned an result with no IPv4 address.",
ConfEntry->name.c_str());
return;
}
// The DNSBL reply must be a valid IPv4 address.
in_addr resultip;
if (inet_pton(AF_INET, ans_record->rdata.c_str(), &resultip) != 1)
{
ConfEntry->stats_errors++;
ServerInstance->SNO.WriteGlobalSno('d', "%s returned an invalid IPv4 address: %s",
ConfEntry->name.c_str(), ans_record->rdata.c_str());
return;
}
// The DNSBL reply should be in the 127.0.0.0/8 range.
if ((resultip.s_addr & 0xFF) != 127)
{
ConfEntry->stats_errors++;
ServerInstance->SNO.WriteGlobalSno('d', "%s returned an IPv4 address which is outside of the 127.0.0.0/8 subnet: %s",
ConfEntry->name.c_str(), ans_record->rdata.c_str());
return;
}
bool match = false;
unsigned int result = 0;
switch (ConfEntry->type)
{
case DNSBLEntry::Type::BITMASK:
{
result = (resultip.s_addr >> 24) & ConfEntry->bitmask;
match = (result != 0);
break;
}
case DNSBLEntry::Type::RECORD:
{
result = resultip.s_addr >> 24;
match = (ConfEntry->records[result] == 1);
break;
}
}
if (match)
{
std::string reason = ConfEntry->reason;
std::string::size_type x = reason.find("%ip%");
while (x != std::string::npos)
{
reason.erase(x, 4);
reason.insert(x, them->GetIPString());
x = reason.find("%ip%");
}
ConfEntry->stats_hits++;
switch (ConfEntry->action)
{
case DNSBLEntry::Action::KILL:
{
ServerInstance->Users.QuitUser(them, "Killed (" + reason + ")");
break;
}
case DNSBLEntry::Action::MARK:
{
if (!ConfEntry->markident.empty())
{
them->WriteNotice("Your ident has been set to " + ConfEntry->markident + " because you matched " + reason);
them->ChangeIdent(ConfEntry->markident);
}
if (!ConfEntry->markhost.empty())
{
them->WriteNotice("Your host has been set to " + ConfEntry->markhost + " because you matched " + reason);
them->ChangeDisplayedHost(ConfEntry->markhost);
}
nameExt.Set(them, ConfEntry->name);
break;
}
case DNSBLEntry::Action::KLINE:
{
KLine* kl = new KLine(ServerInstance->Time(), ConfEntry->xlineduration, ServerInstance->Config->ServerName.c_str(), reason.c_str(),
"*", them->GetIPString());
if (ServerInstance->XLines->AddLine(kl,NULL))
{
ServerInstance->SNO.WriteToSnoMask('x', "K-line added due to DNSBL match on *@%s to expire in %s (on %s): %s",
them->GetIPString().c_str(), InspIRCd::DurationString(kl->duration).c_str(),
InspIRCd::TimeString(kl->expiry).c_str(), reason.c_str());
ServerInstance->XLines->ApplyLines();
}
else
{
delete kl;
return;
}
break;
}
case DNSBLEntry::Action::GLINE:
{
GLine* gl = new GLine(ServerInstance->Time(), ConfEntry->xlineduration, ServerInstance->Config->ServerName.c_str(), reason.c_str(),
"*", them->GetIPString());
if (ServerInstance->XLines->AddLine(gl,NULL))
{
ServerInstance->SNO.WriteToSnoMask('x', "G-line added due to DNSBL match on *@%s to expire in %s (on %s): %s",
them->GetIPString().c_str(), InspIRCd::DurationString(gl->duration).c_str(),
InspIRCd::TimeString(gl->expiry).c_str(), reason.c_str());
ServerInstance->XLines->ApplyLines();
}
else
{
delete gl;
return;
}
break;
}
case DNSBLEntry::Action::ZLINE:
{
ZLine* zl = new ZLine(ServerInstance->Time(), ConfEntry->xlineduration, ServerInstance->Config->ServerName.c_str(), reason.c_str(),
them->GetIPString());
if (ServerInstance->XLines->AddLine(zl,NULL))
{
ServerInstance->SNO.WriteToSnoMask('x', "Z-line added due to DNSBL match on %s to expire in %s (on %s): %s",
them->GetIPString().c_str(), InspIRCd::DurationString(zl->duration).c_str(),
InspIRCd::TimeString(zl->expiry).c_str(), reason.c_str());
ServerInstance->XLines->ApplyLines();
}
else
{
delete zl;
return;
}
break;
}
}
ServerInstance->SNO.WriteGlobalSno('d', "Connecting user %s (%s) detected as being on the '%s' DNS blacklist with result %d",
them->GetFullRealHost().c_str(), them->GetIPString().c_str(), ConfEntry->name.c_str(), result);
}
else
ConfEntry->stats_misses++;
}
void OnError(const DNS::Query *q) override
{
bool is_miss = true;
switch (q->error)
{
case DNS::ERROR_NO_RECORDS:
case DNS::ERROR_DOMAIN_NOT_FOUND:
ConfEntry->stats_misses++;
break;
default:
ConfEntry->stats_errors++;
is_miss = false;
break;
}
LocalUser* them = IS_LOCAL(ServerInstance->Users.FindUUID(theiruid));
if (!them || them->client_sa != theirsa)
return;
intptr_t i = countExt.Get(them);
if (i)
countExt.Set(them, i - 1);
if (is_miss)
return;
ServerInstance->SNO.WriteGlobalSno('d', "An error occurred whilst checking whether %s (%s) is on the '%s' DNS blacklist: %s",
them->GetFullRealHost().c_str(), them->GetIPString().c_str(), ConfEntry->name.c_str(), this->manager->GetErrorStr(q->error).c_str());
}
};
typedef std::vector<std::shared_ptr<DNSBLEntry>> DNSBLConfList;
class ModuleDNSBL : public Module, public Stats::EventListener
{
DNSBLConfList DNSBLConfEntries;
dynamic_reference<DNS::Manager> DNS;
StringExtItem nameExt;
IntExtItem countExt;
public:
ModuleDNSBL()
: Module(VF_VENDOR, "Allows the server administrator to check the IP address of connecting users against a DNSBL.")
, Stats::EventListener(this)
, DNS(this, "DNS")
, nameExt(this, "dnsbl_match", ExtensionItem::EXT_USER)
, countExt(this, "dnsbl_pending", ExtensionItem::EXT_USER)
{
}
void init() override
{
ServerInstance->SNO.EnableSnomask('d', "DNSBL");
}
void Prioritize() override
{
Module* corexline = ServerInstance->Modules.Find("core_xline");
ServerInstance->Modules.SetPriority(this, I_OnSetUserIP, PRIORITY_AFTER, corexline);
}
void ReadConfig(ConfigStatus& status) override
{
DNSBLConfList newentries;
for (const auto& [_, tag] : ServerInstance->Config->ConfTags("dnsbl"))
{
auto entry = std::make_shared<DNSBLEntry>(tag);
newentries.push_back(entry);
}
DNSBLConfEntries.swap(newentries);
}
void OnSetUserIP(LocalUser* user) override
{
if (user->exempt || user->quitting || !DNS || !user->GetClass())
return;
// Clients can't be in a DNSBL if they aren't connected via IPv4 or IPv6.
if (user->client_sa.family() != AF_INET && user->client_sa.family() != AF_INET6)
return;
if (!user->GetClass()->config->getBool("usednsbl", true))
return;
std::string reversedip;
if (user->client_sa.family() == AF_INET)
{
unsigned int a, b, c, d;
d = (unsigned int) (user->client_sa.in4.sin_addr.s_addr >> 24) & 0xFF;
c = (unsigned int) (user->client_sa.in4.sin_addr.s_addr >> 16) & 0xFF;
b = (unsigned int) (user->client_sa.in4.sin_addr.s_addr >> 8) & 0xFF;
a = (unsigned int) user->client_sa.in4.sin_addr.s_addr & 0xFF;
reversedip = ConvToStr(d) + "." + ConvToStr(c) + "." + ConvToStr(b) + "." + ConvToStr(a);
}
else if (user->client_sa.family() == AF_INET6)
{
const unsigned char* ip = user->client_sa.in6.sin6_addr.s6_addr;
const std::string buf = Hex::Encode(ip, 16);
for (const auto& chr : insp::reverse_range(buf))
{
reversedip.push_back(chr);
reversedip.push_back('.');
}
reversedip.erase(reversedip.length() - 1, 1);
}
else
return;
ServerInstance->Logs.Log(MODNAME, LOG_DEBUG, "Reversed IP %s -> %s", user->GetIPString().c_str(), reversedip.c_str());
countExt.Set(user, DNSBLConfEntries.size());
// For each DNSBL, we will run through this lookup
for (unsigned i = 0; i < DNSBLConfEntries.size(); ++i)
{
// Fill hostname with a dnsbl style host (d.c.b.a.domain.tld)
std::string hostname = reversedip + "." + DNSBLConfEntries[i]->domain;
/* now we'd need to fire off lookups for `hostname'. */
DNSBLResolver *r = new DNSBLResolver(*this->DNS, this, nameExt, countExt, hostname, user, DNSBLConfEntries[i]);
try
{
this->DNS->Process(r);
}
catch (DNS::Exception &ex)
{
delete r;
ServerInstance->Logs.Log(MODNAME, LOG_DEBUG, ex.GetReason());
}
if (user->quitting)
break;
}
}
ModResult OnSetConnectClass(LocalUser* user, std::shared_ptr<ConnectClass> myclass) override
{
std::string dnsbl;
if (!myclass->config->readString("dnsbl", dnsbl))
return MOD_RES_PASSTHRU;
std::string* match = nameExt.Get(user);
if (!match)
{
ServerInstance->Logs.Log("CONNECTCLASS", LOG_DEBUG, "The %s connect class is not suitable as it requires a DNSBL mark",
myclass->GetName().c_str());
return MOD_RES_DENY;
}
if (!InspIRCd::Match(*match, dnsbl))
{
ServerInstance->Logs.Log("CONNECTCLASS", LOG_DEBUG, "The %s connect class is not suitable as the DNSBL mark (%s) does not match %s",
myclass->GetName().c_str(), match->c_str(), dnsbl.c_str());
return MOD_RES_DENY;
}
return MOD_RES_PASSTHRU;
}
ModResult OnCheckReady(LocalUser *user) override
{
if (countExt.Get(user))
return MOD_RES_DENY;
return MOD_RES_PASSTHRU;
}
ModResult OnStats(Stats::Context& stats) override
{
if (stats.GetSymbol() != 'd')
return MOD_RES_PASSTHRU;
unsigned long total_hits = 0;
unsigned long total_misses = 0;
unsigned long total_errors = 0;
for (const auto& e : DNSBLConfEntries)
{
total_hits += e->stats_hits;
total_misses += e->stats_misses;
total_errors += e->stats_errors;
stats.AddRow(304, InspIRCd::Format("DNSBLSTATS \"%s\" had %lu hits, %lu misses, and %lu errors",
e->name.c_str(), e->stats_hits, e->stats_misses, e->stats_errors));
}
stats.AddRow(304, "DNSBLSTATS Total hits: " + ConvToStr(total_hits));
stats.AddRow(304, "DNSBLSTATS Total misses: " + ConvToStr(total_misses));
stats.AddRow(304, "DNSBLSTATS Total errors: " + ConvToStr(total_errors));
return MOD_RES_PASSTHRU;
}
};
MODULE_INIT(ModuleDNSBL)
