lokinet/llarp/handlers/exit.cpp
Jeff 388fc53380
match io loop event order on windows/apple to match linux.
on win32/apple reading packets from the interface does not count as an io operation.
manually trigger pump on win32/apple to pretend that it is an io event.
add platform quark function MaybeWakeUpperLayers on vpn::Interface to manaully wake up the other components on platforms that need that (ones on which packet io is not done via io events).
on non linux platforms, use uv_prepare_t instead of uv_check_t as the former triggers before blocking for io, instead of after. this better matches linux's order of operations in libuv.
2021-12-15 15:25:53 -05:00

877 lines
24 KiB
C++

#include "exit.hpp"
#include <llarp/dns/dns.hpp>
#include <llarp/net/net.hpp>
#include <llarp/path/path_context.hpp>
#include <llarp/router/abstractrouter.hpp>
#include <llarp/util/str.hpp>
#include <llarp/util/bits.hpp>
#include <llarp/quic/tunnel.hpp>
#include <llarp/router/i_rc_lookup_handler.hpp>
#include <cassert>
#include "service/protocol_type.hpp"
namespace llarp
{
namespace handlers
{
ExitEndpoint::ExitEndpoint(std::string name, AbstractRouter* r)
: m_Router(r)
, m_Resolver(std::make_shared<dns::Proxy>(r->loop(), this))
, m_Name(std::move(name))
, m_LocalResolverAddr{"127.0.0.1:53"}
, m_QUIC{std::make_shared<quic::TunnelManager>(*this)}
, m_InetToNetwork(name + "_exit_rx", r->loop(), r->loop())
{
m_ShouldInitTun = true;
m_QUIC = std::make_shared<quic::TunnelManager>(*this);
}
ExitEndpoint::~ExitEndpoint() = default;
void
ExitEndpoint::LookupNameAsync(
std::string, std::function<void(std::optional<AddressVariant_t>)> resultHandler)
{
// TODO: implement me
resultHandler(std::nullopt);
}
void
ExitEndpoint::LookupServiceAsync(
std::string, std::string, std::function<void(std::vector<dns::SRVData>)> resultHandler)
{
// TODO: implement me
resultHandler({});
}
std::optional<EndpointBase::AddressVariant_t>
ExitEndpoint::GetEndpointWithConvoTag(service::ConvoTag tag) const
{
for (const auto& [pathID, pk] : m_Paths)
{
if (pathID.as_array() == tag.as_array())
return RouterID{pk.as_array()};
}
for (const auto& [rid, session] : m_SNodeSessions)
{
PathID_t pathID{tag.as_array()};
if (session->GetPathByID(pathID))
return rid;
}
return std::nullopt;
}
std::optional<service::ConvoTag>
ExitEndpoint::GetBestConvoTagFor(AddressVariant_t addr) const
{
if (auto* rid = std::get_if<RouterID>(&addr))
{
service::ConvoTag tag{};
auto visit = [&tag](exit::Endpoint* const ep) -> bool {
if (not ep)
return false;
if (auto path = ep->GetCurrentPath())
tag = service::ConvoTag{path->RXID().as_array()};
return true;
};
if (VisitEndpointsFor(PubKey{*rid}, visit) and not tag.IsZero())
return tag;
auto itr = m_SNodeSessions.find(*rid);
if (itr == m_SNodeSessions.end())
{
return std::nullopt;
}
if (auto path = itr->second->GetPathByRouter(*rid))
{
tag = service::ConvoTag{path->RXID().as_array()};
return tag;
}
return std::nullopt;
}
return std::nullopt;
}
const EventLoop_ptr&
ExitEndpoint::Loop()
{
return m_Router->loop();
}
bool
ExitEndpoint::SendToOrQueue(
service::ConvoTag tag, const llarp_buffer_t& payload, service::ProtocolType type)
{
if (auto maybeAddr = GetEndpointWithConvoTag(tag))
{
if (std::holds_alternative<service::Address>(*maybeAddr))
return false;
if (auto* rid = std::get_if<RouterID>(&*maybeAddr))
{
for (auto [itr, end] = m_ActiveExits.equal_range(PubKey{*rid}); itr != end; ++itr)
{
if (not itr->second->LooksDead(Now()))
{
if (itr->second->QueueInboundTraffic(ManagedBuffer{payload}, type))
return true;
}
}
if (not m_Router->PathToRouterAllowed(*rid))
return false;
ObtainSNodeSession(*rid, [data = payload.copy(), type](auto session) {
if (session and session->IsReady())
{
session->SendPacketToRemote(data, type);
}
});
}
return true;
}
return false;
}
bool
ExitEndpoint::EnsurePathTo(
AddressVariant_t addr,
std::function<void(std::optional<service::ConvoTag>)> hook,
llarp_time_t)
{
if (std::holds_alternative<service::Address>(addr))
return false;
if (auto* rid = std::get_if<RouterID>(&addr))
{
if (m_SNodeKeys.count(PubKey{*rid}) or m_Router->PathToRouterAllowed(*rid))
{
ObtainSNodeSession(
*rid, [hook, routerID = *rid](std::shared_ptr<exit::BaseSession> session) {
if (session and session->IsReady())
{
if (auto path = session->GetPathByRouter(routerID))
{
hook(service::ConvoTag{path->RXID().as_array()});
}
else
hook(std::nullopt);
}
else
hook(std::nullopt);
});
}
else
{
// probably a client
hook(GetBestConvoTagFor(addr));
}
}
return true;
}
util::StatusObject
ExitEndpoint::ExtractStatus() const
{
util::StatusObject obj{{"permitExit", m_PermitExit}, {"ip", m_IfAddr.ToString()}};
util::StatusObject exitsObj{};
for (const auto& item : m_ActiveExits)
{
exitsObj[item.first.ToString()] = item.second->ExtractStatus();
}
obj["exits"] = exitsObj;
return obj;
}
bool
ExitEndpoint::SupportsV6() const
{
return m_UseV6;
}
bool
ExitEndpoint::ShouldHookDNSMessage(const dns::Message& msg) const
{
if (msg.questions.size() == 0)
return false;
// always hook ptr for ranges we own
if (msg.questions[0].qtype == dns::qTypePTR)
{
huint128_t ip;
if (!dns::DecodePTR(msg.questions[0].qname, ip))
return false;
return m_OurRange.Contains(ip);
}
if (msg.questions[0].qtype == dns::qTypeA || msg.questions[0].qtype == dns::qTypeCNAME
|| msg.questions[0].qtype == dns::qTypeAAAA)
{
if (msg.questions[0].IsName("localhost.loki"))
return true;
if (msg.questions[0].HasTLD(".snode"))
return true;
}
return false;
}
bool
ExitEndpoint::HandleHookedDNSMessage(dns::Message msg, std::function<void(dns::Message)> reply)
{
if (msg.questions[0].qtype == dns::qTypePTR)
{
huint128_t ip;
if (!dns::DecodePTR(msg.questions[0].qname, ip))
return false;
if (ip == m_IfAddr)
{
RouterID us = GetRouter()->pubkey();
msg.AddAReply(us.ToString(), 300);
}
else
{
auto itr = m_IPToKey.find(ip);
if (itr != m_IPToKey.end() && m_SNodeKeys.find(itr->second) != m_SNodeKeys.end())
{
RouterID them = itr->second;
msg.AddAReply(them.ToString());
}
else
msg.AddNXReply();
}
}
else if (msg.questions[0].qtype == dns::qTypeCNAME)
{
if (msg.questions[0].IsName("random.snode"))
{
RouterID random;
if (GetRouter()->GetRandomGoodRouter(random))
msg.AddCNAMEReply(random.ToString(), 1);
else
msg.AddNXReply();
}
else if (msg.questions[0].IsName("localhost.loki"))
{
RouterID us = m_Router->pubkey();
msg.AddAReply(us.ToString(), 1);
}
else
msg.AddNXReply();
}
else if (msg.questions[0].qtype == dns::qTypeA || msg.questions[0].qtype == dns::qTypeAAAA)
{
const bool isV6 = msg.questions[0].qtype == dns::qTypeAAAA;
const bool isV4 = msg.questions[0].qtype == dns::qTypeA;
if (msg.questions[0].IsName("random.snode"))
{
RouterID random;
if (GetRouter()->GetRandomGoodRouter(random))
{
msg.AddCNAMEReply(random.ToString(), 1);
auto ip = ObtainServiceNodeIP(random);
msg.AddINReply(ip, false);
}
else
msg.AddNXReply();
reply(msg);
return true;
}
if (msg.questions[0].IsName("localhost.loki"))
{
msg.AddINReply(GetIfAddr(), isV6);
reply(msg);
return true;
}
// forward dns for snode
RouterID r;
if (r.FromString(msg.questions[0].Name()))
{
huint128_t ip;
PubKey pubKey(r);
if (isV4 && SupportsV6())
{
msg.hdr_fields |= dns::flags_QR | dns::flags_AA | dns::flags_RA;
}
else if (m_SNodeKeys.find(pubKey) == m_SNodeKeys.end())
{
// we do not have it mapped, async obtain it
ObtainSNodeSession(
r,
[&, msg = std::make_shared<dns::Message>(msg), reply](
std::shared_ptr<exit::BaseSession> session) {
if (session && session->IsReady())
{
msg->AddINReply(m_KeyToIP[pubKey], isV6);
}
else
{
msg->AddNXReply();
}
reply(*msg);
});
return true;
}
else
{
// we have it mapped already as a service node
auto itr = m_KeyToIP.find(pubKey);
if (itr != m_KeyToIP.end())
{
ip = itr->second;
msg.AddINReply(ip, isV6);
}
else // fallback case that should never happen (probably)
msg.AddNXReply();
}
}
else
msg.AddNXReply();
}
reply(msg);
return true;
}
void
ExitEndpoint::ObtainSNodeSession(const RouterID& router, exit::SessionReadyFunc obtainCb)
{
if (not m_Router->rcLookupHandler().SessionIsAllowed(router))
{
obtainCb(nullptr);
return;
}
ObtainServiceNodeIP(router);
m_SNodeSessions[router]->AddReadyHook(obtainCb);
}
llarp_time_t
ExitEndpoint::Now() const
{
return m_Router->Now();
}
bool
ExitEndpoint::VisitEndpointsFor(
const PubKey& pk, std::function<bool(exit::Endpoint* const)> visit) const
{
for (auto [itr, end] = m_ActiveExits.equal_range(pk); itr != end; ++itr)
{
if (not visit(itr->second.get()))
return true;
}
return false;
}
void
ExitEndpoint::Flush()
{
m_InetToNetwork.Process([&](Pkt_t& pkt) {
PubKey pk;
{
auto itr = m_IPToKey.find(pkt.dstv6());
if (itr == m_IPToKey.end())
{
// drop
LogWarn(Name(), " dropping packet, has no session at ", pkt.dstv6());
return;
}
pk = itr->second;
}
// check if this key is a service node
if (m_SNodeKeys.count(pk))
{
// check if it's a service node session we made and queue it via our
// snode session that we made otherwise use an inbound session that
// was made by the other service node
auto itr = m_SNodeSessions.find(pk);
if (itr != m_SNodeSessions.end())
{
itr->second->SendPacketToRemote(pkt.ConstBuffer(), service::ProtocolType::TrafficV4);
return;
}
}
auto tryFlushingTraffic = [&](exit::Endpoint* const ep) -> bool {
if (!ep->QueueInboundTraffic(
ManagedBuffer{pkt.Buffer()}, service::ProtocolType::TrafficV4))
{
LogWarn(
Name(),
" dropped inbound traffic for session ",
pk,
" as we are overloaded (probably)");
// continue iteration
return true;
}
// break iteration
return false;
};
if (!VisitEndpointsFor(pk, tryFlushingTraffic))
{
// we may have all dead sessions, wtf now?
LogWarn(
Name(),
" dropped inbound traffic for session ",
pk,
" as we have no working endpoints");
}
});
for (auto& [pubkey, endpoint] : m_ActiveExits)
{
if (!endpoint->Flush())
{
LogWarn("exit session with ", pubkey, " dropped packets");
}
}
for (auto& [id, session] : m_SNodeSessions)
{
session->FlushUpstream();
session->FlushDownstream();
}
}
bool
ExitEndpoint::Start()
{
// map our address
const PubKey us(m_Router->pubkey());
const huint128_t ip = GetIfAddr();
m_KeyToIP[us] = ip;
m_IPToKey[ip] = us;
m_IPActivity[ip] = std::numeric_limits<llarp_time_t>::max();
m_SNodeKeys.insert(us);
if (m_ShouldInitTun)
{
vpn::InterfaceInfo info;
info.ifname = m_ifname;
info.addrs.emplace(m_OurRange);
m_NetIf = GetRouter()->GetVPNPlatform()->ObtainInterface(std::move(info), m_Router);
if (not m_NetIf)
{
llarp::LogError("Could not create interface");
return false;
}
if (not GetRouter()->loop()->add_network_interface(
m_NetIf, [this](net::IPPacket pkt) { OnInetPacket(std::move(pkt)); }))
{
llarp::LogWarn("Could not create tunnel for exit endpoint");
return false;
}
GetRouter()->loop()->add_ticker([this] { Flush(); });
llarp::LogInfo("Trying to start resolver ", m_LocalResolverAddr);
return m_Resolver->Start(m_LocalResolverAddr, m_UpstreamResolvers, {});
}
return true;
}
AbstractRouter*
ExitEndpoint::GetRouter()
{
return m_Router;
}
huint128_t
ExitEndpoint::GetIfAddr() const
{
return m_IfAddr;
}
bool
ExitEndpoint::Stop()
{
for (auto& item : m_SNodeSessions)
item.second->Stop();
return true;
}
bool
ExitEndpoint::ShouldRemove() const
{
for (auto& item : m_SNodeSessions)
if (!item.second->ShouldRemove())
return false;
return true;
}
bool
ExitEndpoint::HasLocalMappedAddrFor(const PubKey& pk) const
{
return m_KeyToIP.find(pk) != m_KeyToIP.end();
}
huint128_t
ExitEndpoint::GetIPForIdent(const PubKey pk)
{
huint128_t found{};
if (!HasLocalMappedAddrFor(pk))
{
// allocate and map
found = AllocateNewAddress();
if (!m_KeyToIP.emplace(pk, found).second)
{
LogError(Name(), "failed to map ", pk, " to ", found);
return found;
}
if (!m_IPToKey.emplace(found, pk).second)
{
LogError(Name(), "failed to map ", found, " to ", pk);
return found;
}
if (HasLocalMappedAddrFor(pk))
LogInfo(Name(), " mapping ", pk, " to ", found);
else
LogError(Name(), "failed to map ", pk, " to ", found);
}
else
found = m_KeyToIP[pk];
MarkIPActive(found);
m_KeyToIP.rehash(0);
assert(HasLocalMappedAddrFor(pk));
return found;
}
huint128_t
ExitEndpoint::AllocateNewAddress()
{
if (m_NextAddr < m_HigestAddr)
return ++m_NextAddr;
// find oldest activity ip address
huint128_t found = {0};
llarp_time_t min = std::numeric_limits<llarp_time_t>::max();
for (const auto& [addr, time] : m_IPActivity)
{
if (time < min)
{
found.h = addr.h;
min = time;
}
}
// kick old ident off exit
// TODO: DoS
PubKey pk = m_IPToKey[found];
KickIdentOffExit(pk);
return found;
}
EndpointBase::AddressVariant_t
ExitEndpoint::LocalAddress() const
{
return RouterID{m_Router->pubkey()};
}
void
ExitEndpoint::SRVRecordsChanged()
{
m_Router->ModifyOurRC(
[srvRecords = SRVRecords()](RouterContact rc) -> std::optional<RouterContact> {
// check if there are any new srv records
bool shouldUpdate = false;
for (const auto& rcSrv : rc.srvRecords)
{
if (srvRecords.count(rcSrv) == 0)
shouldUpdate = true;
}
// no new records so don't modify
if (not shouldUpdate)
return std::nullopt;
// we got new entries so we clear the whole vector on the rc and recreate it
rc.srvRecords.clear();
for (auto& record : srvRecords)
rc.srvRecords.emplace_back(record);
// set the version to 1 because we have srv records
rc.version = 1;
return rc;
});
}
std::optional<EndpointBase::SendStat> ExitEndpoint::GetStatFor(AddressVariant_t) const
{
/// TODO: implement me
return std::nullopt;
}
std::unordered_set<EndpointBase::AddressVariant_t>
ExitEndpoint::AllRemoteEndpoints() const
{
std::unordered_set<AddressVariant_t> remote;
for (const auto& [path, pubkey] : m_Paths)
{
remote.insert(RouterID{pubkey});
}
return remote;
}
bool
ExitEndpoint::QueueOutboundTraffic(net::IPPacket pkt)
{
return m_NetIf && m_NetIf->WritePacket(std::move(pkt));
}
void
ExitEndpoint::KickIdentOffExit(const PubKey& pk)
{
LogInfo(Name(), " kicking ", pk, " off exit");
huint128_t ip = m_KeyToIP[pk];
m_KeyToIP.erase(pk);
m_IPToKey.erase(ip);
for (auto [exit_itr, end] = m_ActiveExits.equal_range(pk); exit_itr != end;)
exit_itr = m_ActiveExits.erase(exit_itr);
}
void
ExitEndpoint::MarkIPActive(huint128_t ip)
{
m_IPActivity[ip] = GetRouter()->Now();
}
void
ExitEndpoint::OnInetPacket(net::IPPacket pkt)
{
m_InetToNetwork.Emplace(std::move(pkt));
}
bool
ExitEndpoint::QueueSNodePacket(const llarp_buffer_t& buf, huint128_t from)
{
net::IPPacket pkt;
if (!pkt.Load(buf))
return false;
// rewrite ip
if (m_UseV6)
pkt.UpdateIPv6Address(from, m_IfAddr);
else
pkt.UpdateIPv4Address(xhtonl(net::TruncateV6(from)), xhtonl(net::TruncateV6(m_IfAddr)));
return m_NetIf and m_NetIf->WritePacket(std::move(pkt));
}
exit::Endpoint*
ExitEndpoint::FindEndpointByPath(const PathID_t& path)
{
exit::Endpoint* endpoint = nullptr;
PubKey pk;
if (auto itr = m_Paths.find(path); itr != m_Paths.end())
pk = itr->second;
else
return nullptr;
if (auto itr = m_ActiveExits.find(pk); itr != m_ActiveExits.end())
{
if (itr->second->PubKey() == pk)
endpoint = itr->second.get();
}
return endpoint;
}
bool
ExitEndpoint::UpdateEndpointPath(const PubKey& remote, const PathID_t& next)
{
// check if already mapped
if (auto itr = m_Paths.find(next); itr != m_Paths.end())
return false;
m_Paths.emplace(next, remote);
return true;
}
void
ExitEndpoint::Configure(const NetworkConfig& networkConfig, const DnsConfig& dnsConfig)
{
/*
* TODO: pre-config refactor, this was checking a couple things that were extremely vague
* these could have appeared on either [dns] or [network], but they weren't documented
* anywhere
*
if (k == "type" && v == "null")
{
m_ShouldInitTun = false;
return true;
}
if (k == "exit")
{
m_PermitExit = IsTrueValue(v.c_str());
return true;
}
*/
if (networkConfig.m_endpointType == "null")
{
m_ShouldInitTun = false;
}
m_LocalResolverAddr = dnsConfig.m_bind;
m_UpstreamResolvers = dnsConfig.m_upstreamDNS;
m_OurRange = networkConfig.m_ifaddr;
if (!m_OurRange.addr.h)
{
const auto maybe = llarp::FindFreeRange();
if (not maybe.has_value())
throw std::runtime_error("cannot find free interface range");
m_OurRange = *maybe;
}
const auto host_str = m_OurRange.BaseAddressString();
// string, or just a plain char array?
m_IfAddr = m_OurRange.addr;
m_NextAddr = m_IfAddr;
m_HigestAddr = m_OurRange.HighestAddr();
m_UseV6 = not m_OurRange.IsV4();
m_ifname = networkConfig.m_ifname;
if (m_ifname.empty())
{
const auto maybe = llarp::FindFreeTun();
if (not maybe.has_value())
throw std::runtime_error("cannot find free interface name");
m_ifname = *maybe;
}
LogInfo(Name(), " set ifname to ", m_ifname);
if (auto* quic = GetQUICTunnel())
{
quic->listen([ifaddr = net::TruncateV6(m_IfAddr)](std::string_view, uint16_t port) {
return llarp::SockAddr{ifaddr, huint16_t{port}};
});
}
// TODO: "exit-whitelist" and "exit-blacklist"
// (which weren't originally implemented)
}
huint128_t
ExitEndpoint::ObtainServiceNodeIP(const RouterID& other)
{
const PubKey pubKey{other};
const PubKey us{m_Router->pubkey()};
// just in case
if (pubKey == us)
return m_IfAddr;
huint128_t ip = GetIPForIdent(pubKey);
if (m_SNodeKeys.emplace(pubKey).second)
{
auto session = std::make_shared<exit::SNodeSession>(
other,
[this, ip](const auto& buf) { return QueueSNodePacket(buf, ip); },
GetRouter(),
2,
1,
true,
this);
// this is a new service node make an outbound session to them
m_SNodeSessions[other] = session;
}
return ip;
}
quic::TunnelManager*
ExitEndpoint::GetQUICTunnel()
{
return m_QUIC.get();
}
bool
ExitEndpoint::AllocateNewExit(const PubKey pk, const PathID_t& path, bool wantInternet)
{
if (wantInternet && !m_PermitExit)
return false;
path::HopHandler_ptr handler =
m_Router->pathContext().GetByUpstream(m_Router->pubkey(), path);
if (handler == nullptr)
return false;
auto ip = GetIPForIdent(pk);
if (GetRouter()->pathContext().TransitHopPreviousIsRouter(path, pk.as_array()))
{
// we think this path belongs to a service node
// mark it as such so we don't make an outbound session to them
m_SNodeKeys.emplace(pk.as_array());
}
m_ActiveExits.emplace(
pk, std::make_unique<exit::Endpoint>(pk, handler, !wantInternet, ip, this));
m_Paths[path] = pk;
return HasLocalMappedAddrFor(pk);
}
std::string
ExitEndpoint::Name() const
{
return m_Name;
}
void
ExitEndpoint::DelEndpointInfo(const PathID_t& path)
{
m_Paths.erase(path);
}
void
ExitEndpoint::RemoveExit(const exit::Endpoint* ep)
{
for (auto [itr, end] = m_ActiveExits.equal_range(ep->PubKey()); itr != end; ++itr)
{
if (itr->second->GetCurrentPath() == ep->GetCurrentPath())
{
m_ActiveExits.erase(itr);
// now ep is gone af
return;
}
}
}
void
ExitEndpoint::Tick(llarp_time_t now)
{
{
auto itr = m_SNodeSessions.begin();
while (itr != m_SNodeSessions.end())
{
if (itr->second->IsExpired(now))
itr = m_SNodeSessions.erase(itr);
else
{
itr->second->Tick(now);
++itr;
}
}
}
{
// expire
auto itr = m_ActiveExits.begin();
while (itr != m_ActiveExits.end())
{
if (itr->second->IsExpired(now))
itr = m_ActiveExits.erase(itr);
else
++itr;
}
// pick chosen exits and tick
m_ChosenExits.clear();
itr = m_ActiveExits.begin();
while (itr != m_ActiveExits.end())
{
// do we have an exit set for this key?
if (m_ChosenExits.find(itr->first) != m_ChosenExits.end())
{
// yes
if (m_ChosenExits[itr->first]->createdAt < itr->second->createdAt)
{
// if the iterators's exit is newer use it for the chosen exit for
// key
if (!itr->second->LooksDead(now))
m_ChosenExits[itr->first] = itr->second.get();
}
}
else if (!itr->second->LooksDead(now)) // set chosen exit if not dead for key that
// doesn't have one yet
m_ChosenExits[itr->first] = itr->second.get();
// tick which clears the tx rx counters
itr->second->Tick(now);
++itr;
}
}
}
} // namespace handlers
} // namespace llarp