lokinet/llarp/path/pathbuilder.cpp
2021-03-05 13:36:31 -04:00

446 lines
12 KiB
C++

#include <path/pathbuilder.hpp>
#include <crypto/crypto.hpp>
#include <messages/relay_commit.hpp>
#include <nodedb.hpp>
#include <path/path_context.hpp>
#include <profiling.hpp>
#include <router/abstractrouter.hpp>
#include <util/buffer.hpp>
#include <tooling/path_event.hpp>
#include <functional>
namespace llarp
{
struct AsyncPathKeyExchangeContext : std::enable_shared_from_this<AsyncPathKeyExchangeContext>
{
using WorkFunc_t = std::function<void(void)>;
using WorkerFunc_t = std::function<void(WorkFunc_t)>;
using Path_t = path::Path_ptr;
using PathSet_t = path::PathSet_ptr;
PathSet_t pathset = nullptr;
Path_t path = nullptr;
using Handler = std::function<void(std::shared_ptr<AsyncPathKeyExchangeContext>)>;
Handler result;
size_t idx = 0;
AbstractRouter* router = nullptr;
WorkerFunc_t work;
EventLoop_ptr loop;
LR_CommitMessage LRCM;
void
GenerateNextKey()
{
// current hop
auto& hop = path->hops[idx];
auto& frame = LRCM.frames[idx];
auto crypto = CryptoManager::instance();
// generate key
crypto->encryption_keygen(hop.commkey);
hop.nonce.Randomize();
// do key exchange
if (!crypto->dh_client(hop.shared, hop.rc.enckey, hop.commkey, hop.nonce))
{
LogError(pathset->Name(), " Failed to generate shared key for path build");
return;
}
// generate nonceXOR valueself->hop->pathKey
crypto->shorthash(hop.nonceXOR, llarp_buffer_t(hop.shared));
++idx;
bool isFarthestHop = idx == path->hops.size();
LR_CommitRecord record;
if (isFarthestHop)
{
hop.upstream = hop.rc.pubkey;
}
else
{
hop.upstream = path->hops[idx].rc.pubkey;
record.nextRC = std::make_unique<RouterContact>(path->hops[idx].rc);
}
// build record
record.lifetime = path::default_lifetime;
record.version = LLARP_PROTO_VERSION;
record.txid = hop.txID;
record.rxid = hop.rxID;
record.tunnelNonce = hop.nonce;
record.nextHop = hop.upstream;
record.commkey = seckey_topublic(hop.commkey);
llarp_buffer_t buf(frame.data(), frame.size());
buf.cur = buf.base + EncryptedFrameOverheadSize;
// encode record
if (!record.BEncode(&buf))
{
// failed to encode?
LogError(pathset->Name(), " Failed to generate Commit Record");
DumpBuffer(buf);
return;
}
// use ephemeral keypair for frame
SecretKey framekey;
crypto->encryption_keygen(framekey);
if (!frame.EncryptInPlace(framekey, hop.rc.enckey))
{
LogError(pathset->Name(), " Failed to encrypt LRCR");
return;
}
if (isFarthestHop)
{
// farthest hop
// TODO: encrypt junk frames because our public keys are not eligator
loop->call([self = shared_from_this()] { self->result(self); });
}
else
{
// next hop
work([self = shared_from_this()] { self->GenerateNextKey(); });
}
}
/// Generate all keys asynchronously and call handler when done
void
AsyncGenerateKeys(Path_t p, EventLoop_ptr l, WorkerFunc_t worker, Handler func)
{
path = p;
loop = std::move(l);
result = func;
work = worker;
for (size_t i = 0; i < path::max_len; ++i)
{
LRCM.frames[i].Randomize();
}
work([self = shared_from_this()] { self->GenerateNextKey(); });
}
};
static void
PathBuilderKeysGenerated(std::shared_ptr<AsyncPathKeyExchangeContext> ctx)
{
if (!ctx->pathset->IsStopped())
{
ctx->router->NotifyRouterEvent<tooling::PathAttemptEvent>(ctx->router->pubkey(), ctx->path);
const RouterID remote = ctx->path->Upstream();
const ILinkMessage* msg = &ctx->LRCM;
auto sentHandler = [ctx](auto status) {
if (status == SendStatus::Success)
{
ctx->router->pathContext().AddOwnPath(ctx->pathset, ctx->path);
ctx->pathset->PathBuildStarted(std::move(ctx->path));
}
else
{
LogError(ctx->pathset->Name(), " failed to send LRCM to ", ctx->path->Upstream());
ctx->path->EnterState(path::ePathFailed, ctx->router->Now());
}
ctx->path = nullptr;
ctx->pathset = nullptr;
};
if (ctx->router->SendToOrQueue(remote, msg, sentHandler))
{
// persist session with router until this path is done
ctx->router->PersistSessionUntil(remote, ctx->path->ExpireTime());
}
else
{
LogError(ctx->pathset->Name(), " failed to queue LRCM to ", remote);
sentHandler(SendStatus::NoLink);
}
}
}
namespace path
{
Builder::Builder(AbstractRouter* p_router, size_t pathNum, size_t hops)
: path::PathSet(pathNum), _run(true), m_router(p_router), numHops(hops)
{
CryptoManager::instance()->encryption_keygen(enckey);
}
void
Builder::ResetInternalState()
{
buildIntervalLimit = MIN_PATH_BUILD_INTERVAL;
lastBuild = 0s;
}
void Builder::Tick(llarp_time_t)
{
const auto now = llarp::time_now_ms();
ExpirePaths(now, m_router);
if (ShouldBuildMore(now))
BuildOne();
TickPaths(m_router);
if (m_BuildStats.attempts > 50)
{
if (m_BuildStats.SuccessRatio() <= BuildStats::MinGoodRatio && now - m_LastWarn > 5s)
{
LogWarn(Name(), " has a low path build success. ", m_BuildStats);
m_LastWarn = now;
}
}
}
util::StatusObject
Builder::ExtractStatus() const
{
util::StatusObject obj{
{"buildStats", m_BuildStats.ExtractStatus()},
{"numHops", uint64_t(numHops)},
{"numPaths", uint64_t(numDesiredPaths)}};
std::transform(
m_Paths.begin(),
m_Paths.end(),
std::back_inserter(obj["paths"]),
[](const auto& item) -> util::StatusObject { return item.second->ExtractStatus(); });
return obj;
}
std::optional<RouterContact>
Builder::SelectFirstHop(const std::set<RouterID>& exclude) const
{
std::optional<RouterContact> found = std::nullopt;
m_router->ForEachPeer(
[&](const ILinkSession* s, bool isOutbound) {
if (s && s->IsEstablished() && isOutbound && not found.has_value())
{
const RouterContact rc = s->GetRemoteRC();
#ifndef TESTNET
if (m_router->IsBootstrapNode(rc.pubkey))
return;
#endif
if (exclude.count(rc.pubkey))
return;
found = rc;
}
},
true);
return found;
}
std::optional<std::vector<RouterContact>>
Builder::GetHopsForBuild()
{
auto filter = [r = m_router](const auto& rc) -> bool {
return not r->routerProfiling().IsBadForPath(rc.pubkey);
};
if (const auto maybe = m_router->nodedb()->GetRandom(filter))
{
return GetHopsAlignedToForBuild(maybe->pubkey);
}
return std::nullopt;
}
bool
Builder::Stop()
{
_run = false;
return true;
}
bool
Builder::IsStopped() const
{
return !_run.load();
}
bool
Builder::ShouldRemove() const
{
return IsStopped();
}
const SecretKey&
Builder::GetTunnelEncryptionSecretKey() const
{
return enckey;
}
bool
Builder::BuildCooldownHit(llarp_time_t now) const
{
return now < lastBuild + buildIntervalLimit;
}
bool
Builder::ShouldBuildMore(llarp_time_t now) const
{
if (IsStopped())
return false;
if (BuildCooldownHit(now))
return false;
return PathSet::ShouldBuildMore(now);
}
void
Builder::BuildOne(PathRole roles)
{
if (const auto maybe = GetHopsForBuild(); maybe.has_value())
Build(*maybe, roles);
}
bool Builder::UrgentBuild(llarp_time_t) const
{
return buildIntervalLimit > MIN_PATH_BUILD_INTERVAL * 4;
}
std::optional<std::vector<RouterContact>>
Builder::GetHopsAlignedToForBuild(RouterID endpoint, const std::set<RouterID>& exclude)
{
const auto pathConfig = m_router->GetConfig()->paths;
std::vector<RouterContact> hops;
{
const auto maybe = SelectFirstHop(exclude);
if (not maybe.has_value())
return std::nullopt;
hops.emplace_back(*maybe);
};
RouterContact endpointRC;
if (const auto maybe = m_router->nodedb()->Get(endpoint))
{
endpointRC = *maybe;
}
else
return std::nullopt;
for (size_t idx = hops.size(); idx < numHops; ++idx)
{
if (idx + 1 == numHops)
{
hops.emplace_back(endpointRC);
}
else
{
auto filter =
[&hops, r = m_router, endpointRC, pathConfig, exclude](const auto& rc) -> bool {
if (exclude.count(rc.pubkey))
return false;
std::set<RouterContact> hopsSet;
hopsSet.insert(endpointRC);
hopsSet.insert(hops.begin(), hops.end());
if (r->routerProfiling().IsBadForPath(rc.pubkey))
return false;
for (const auto& hop : hopsSet)
{
if (hop.pubkey == rc.pubkey)
return false;
}
hopsSet.insert(rc);
if (not pathConfig.Acceptable(hopsSet))
return false;
return rc.pubkey != endpointRC.pubkey;
};
if (const auto maybe = m_router->nodedb()->GetRandom(filter))
hops.emplace_back(*maybe);
else
return std::nullopt;
}
}
return hops;
}
bool
Builder::BuildOneAlignedTo(const RouterID remote)
{
if (const auto maybe = GetHopsAlignedToForBuild(remote); maybe.has_value())
{
LogInfo(Name(), " building path to ", remote);
Build(*maybe);
return true;
}
return false;
}
llarp_time_t
Builder::Now() const
{
return m_router->Now();
}
void
Builder::Build(std::vector<RouterContact> hops, PathRole roles)
{
if (IsStopped())
return;
lastBuild = Now();
// async generate keys
auto ctx = std::make_shared<AsyncPathKeyExchangeContext>();
ctx->router = m_router;
auto self = GetSelf();
ctx->pathset = self;
std::string path_shortName = "[path " + m_router->ShortName() + "-";
path_shortName = path_shortName + std::to_string(m_router->NextPathBuildNumber()) + "]";
auto path = std::make_shared<path::Path>(hops, self.get(), roles, std::move(path_shortName));
LogInfo(Name(), " build ", path->ShortName(), ": ", path->HopsString());
path->SetBuildResultHook([self](Path_ptr p) { self->HandlePathBuilt(p); });
ctx->AsyncGenerateKeys(
path,
m_router->loop(),
[r = m_router](auto func) { r->QueueWork(std::move(func)); },
&PathBuilderKeysGenerated);
}
void
Builder::HandlePathBuilt(Path_ptr p)
{
buildIntervalLimit = MIN_PATH_BUILD_INTERVAL;
m_router->routerProfiling().MarkPathSuccess(p.get());
LogInfo(p->Name(), " built latency=", p->intro.latency);
m_BuildStats.success++;
}
void
Builder::HandlePathBuildFailed(Path_ptr p)
{
m_router->routerProfiling().MarkPathFail(p.get());
PathSet::HandlePathBuildFailed(p);
DoPathBuildBackoff();
}
void
Builder::DoPathBuildBackoff()
{
static constexpr std::chrono::milliseconds MaxBuildInterval = 30s;
// linear backoff
buildIntervalLimit = std::min(MIN_PATH_BUILD_INTERVAL + buildIntervalLimit, MaxBuildInterval);
LogWarn(Name(), " build interval is now ", buildIntervalLimit);
}
void
Builder::HandlePathBuildTimeout(Path_ptr p)
{
m_router->routerProfiling().MarkPathTimeout(p.get());
PathSet::HandlePathBuildTimeout(p);
DoPathBuildBackoff();
}
void
Builder::ManualRebuild(size_t num, PathRole roles)
{
LogDebug(Name(), " manual rebuild ", num);
while (num--)
BuildOne(roles);
}
} // namespace path
} // namespace llarp