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Rate limit peer list requests

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Send an empty response if the request comes too soon
This commit is contained in:
SChernykh 2023-06-29 18:20:07 +02:00
parent 375bf56e2e
commit e5bf27030d
2 changed files with 31 additions and 39 deletions
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67
src/p2p_server.cpp
View file

@ -38,6 +38,7 @@ static const char* seed_nodes_mini[] = { "seeds-mini.p2pool.io", "" };
static constexpr int DEFAULT_BACKLOG = 16;
static constexpr uint64_t DEFAULT_BAN_TIME = 600;
static constexpr uint64_t PEER_REQUEST_DELAY = 60;
namespace p2pool {
@ -373,7 +374,7 @@ void P2PServer::update_peer_list()
void P2PServer::send_peer_list_request(P2PClient* client, uint64_t cur_time)
{
// Send peer list requests at random intervals (60-120 seconds)
client->m_nextOutgoingPeerListRequest = cur_time + (60 + (get_random64() % 61));
client->m_nextOutgoingPeerListRequest = cur_time + (PEER_REQUEST_DELAY + (get_random64() % (PEER_REQUEST_DELAY + 1)));
const bool result = send(client,
[client](uint8_t* buf, size_t buf_size)
@ -1227,8 +1228,7 @@ P2PServer::P2PClient::P2PClient()
, m_handshakeComplete(false)
, m_handshakeInvalid(false)
, m_listenPort(-1)
, m_fastPeerListRequestCount(0)
, m_prevIncomingPeerListRequest(0)
, m_prevPeersSent(0)
, m_nextOutgoingPeerListRequest(0)
, m_lastPeerListRequestTime{}
, m_peerListPendingRequests(0)
@ -1329,8 +1329,7 @@ void P2PServer::P2PClient::reset()
m_handshakeComplete = false;
m_handshakeInvalid = false;
m_listenPort = -1;
m_fastPeerListRequestCount = 0;
m_prevIncomingPeerListRequest = 0;
m_prevPeersSent = 0;
m_nextOutgoingPeerListRequest = 0;
m_lastPeerListRequestTime = {};
m_peerListPendingRequests = 0;
@ -2118,46 +2117,40 @@ bool P2PServer::P2PClient::on_peer_list_request(const uint8_t*)
P2PServer* server = static_cast<P2PServer*>(m_owner);
server->check_event_loop_thread(__func__);
const uint64_t cur_time = seconds_since_epoch();
const bool first = (m_prevIncomingPeerListRequest == 0);
// Allow peer list requests no more than once every 30 seconds
if (cur_time - m_prevIncomingPeerListRequest < 30) {
++m_fastPeerListRequestCount;
if (m_fastPeerListRequestCount >= 3) {
LOGWARN(4, "peer " << static_cast<char*>(m_addrString) << " is sending PEER_LIST_REQUEST too often");
return false;
}
}
m_prevIncomingPeerListRequest = cur_time;
Peer peers[PEER_LIST_RESPONSE_MAX_PEERS];
uint32_t num_selected_peers = 0;
// Send every 4th peer on average, selected at random
const uint32_t peers_to_send_target = std::min<uint32_t>(PEER_LIST_RESPONSE_MAX_PEERS, std::max<uint32_t>(1, server->m_numConnections / 4));
uint32_t n = 0;
const uint64_t cur_time = seconds_since_epoch();
const bool first = (m_prevPeersSent == 0);
for (P2PClient* client = static_cast<P2PClient*>(server->m_connectedClientsList->m_next); client != server->m_connectedClientsList; client = static_cast<P2PClient*>(client->m_next)) {
if (!client->is_good() || (client->m_addr == m_addr)) {
continue;
}
// Rate limit peer list requests (send an empty response if the request comes too soon)
if (first || (cur_time >= m_prevPeersSent + PEER_REQUEST_DELAY)) {
m_prevPeersSent = cur_time;
const Peer p{ client->m_isV6, client->m_addr, client->m_listenPort, 0, 0 };
++n;
// Send every 4th peer on average, selected at random
const uint32_t peers_to_send_target = std::min<uint32_t>(PEER_LIST_RESPONSE_MAX_PEERS, std::max<uint32_t>(1, server->m_numConnections / 4));
uint32_t n = 0;
// Use https://en.wikipedia.org/wiki/Reservoir_sampling algorithm
if (num_selected_peers < peers_to_send_target) {
peers[num_selected_peers++] = p;
continue;
}
for (P2PClient* client = static_cast<P2PClient*>(server->m_connectedClientsList->m_next); client != server->m_connectedClientsList; client = static_cast<P2PClient*>(client->m_next)) {
if (!client->is_good() || (client->m_addr == m_addr)) {
continue;
}
uint64_t k;
umul128(server->get_random64(), n, &k);
const Peer p{ client->m_isV6, client->m_addr, client->m_listenPort, 0, 0 };
++n;
if (k < peers_to_send_target) {
peers[k] = p;
// Use https://en.wikipedia.org/wiki/Reservoir_sampling algorithm
if (num_selected_peers < peers_to_send_target) {
peers[num_selected_peers++] = p;
continue;
}
uint64_t k;
umul128(server->get_random64(), n, &k);
if (k < peers_to_send_target) {
peers[k] = p;
}
}
}

3
src/p2p_server.h
View file

@ -131,8 +131,7 @@ public:
bool m_handshakeInvalid;
int m_listenPort;
uint32_t m_fastPeerListRequestCount;
uint64_t m_prevIncomingPeerListRequest;
uint64_t m_prevPeersSent;
uint64_t m_nextOutgoingPeerListRequest;
std::chrono::high_resolution_clock::time_point m_lastPeerListRequestTime;
int m_peerListPendingRequests;