Skip to content

Commit

Permalink
Gives seednode priority over dnsseed if both are provided
Browse files Browse the repository at this point in the history
  • Loading branch information
@sr-gi
sr-gi committed Feb 2, 2024
1 parent 5b8c597 commit 206094a
Show file tree
Hide file tree
Showing 2 changed files with 119 additions and 82 deletions.
199 changes: 117 additions & 82 deletions src/net.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -2189,7 +2189,30 @@ void CConnman::ThreadDNSAddressSeed()
std::vector<std::string> seeds = m_params.DNSSeeds();
Shuffle(seeds.begin(), seeds.end(), rng);
int seeds_right_now = 0; // Number of seeds left before testing if we have enough connections
int found = 0;
int target_outbound_connections = 2;
int outbound_connection_count = 0;

auto start = NodeClock::now();
if (gArgs.IsArgSet("-seednode")) {
LogPrintf("-seednode enabled. Trying the provided seeds before defaulting to the dnsseeds.\n");
while (!interruptNet) {
if (!interruptNet.sleep_for(std::chrono::milliseconds(500)))
return;

// Abort if we have spent enough time without reaching our target.
// Giving seed nodes 30 seconds so this does not become a race against fixedseeds (which triggers after 1 min)
if (NodeClock::now() > start + 30s) {
LogPrintf("Couldn't connect to enough peers via seed nodes. Handing fetch logic to the DNS seeds.\n");
break;
}

outbound_connection_count = GetFullOutboundConnCount();
if (outbound_connection_count >= target_outbound_connections) {
LogPrintf("P2P peers available. Finished fetching data from seed nodes.\n");
break;
}
}
}

if (gArgs.GetBoolArg("-forcednsseed", DEFAULT_FORCEDNSSEED)) {
// When -forcednsseed is provided, query all.
Expand All @@ -2201,98 +2224,97 @@ void CConnman::ThreadDNSAddressSeed()
seeds_right_now = seeds.size();
}

// goal: only query DNS seed if address need is acute
// * If we have a reasonable number of peers in addrman, spend
// some time trying them first. This improves user privacy by
// creating fewer identifying DNS requests, reduces trust by
// giving seeds less influence on the network topology, and
// reduces traffic to the seeds.
// * When querying DNS seeds query a few at once, this ensures
// that we don't give DNS seeds the ability to eclipse nodes
// that query them.
// * If we continue having problems, eventually query all the
// DNS seeds, and if that fails too, also try the fixed seeds.
// (done in ThreadOpenConnections)
const std::chrono::seconds seeds_wait_time = (addrman.Size() >= DNSSEEDS_DELAY_PEER_THRESHOLD ? DNSSEEDS_DELAY_MANY_PEERS : DNSSEEDS_DELAY_FEW_PEERS);

for (const std::string& seed : seeds) {
if (seeds_right_now == 0) {
seeds_right_now += DNSSEEDS_TO_QUERY_AT_ONCE;

if (addrman.Size() > 0) {
LogPrintf("Waiting %d seconds before querying DNS seeds.\n", seeds_wait_time.count());
std::chrono::seconds to_wait = seeds_wait_time;
while (to_wait.count() > 0) {
// if sleeping for the MANY_PEERS interval, wake up
// early to see if we have enough peers and can stop
// this thread entirely freeing up its resources
std::chrono::seconds w = std::min(DNSSEEDS_DELAY_FEW_PEERS, to_wait);
if (!interruptNet.sleep_for(w)) return;
to_wait -= w;

int nRelevant = 0;
{
LOCK(m_nodes_mutex);
for (const CNode* pnode : m_nodes) {
if (pnode->fSuccessfullyConnected && pnode->IsFullOutboundConn()) ++nRelevant;
// Proceed with dnsseeds if seednodes hasn't reached the target or if forcednsseed is set
if (outbound_connection_count < target_outbound_connections || seeds_right_now) {
// goal: only query DNS seed if address need is acute
// * If we have a reasonable number of peers in addrman, spend
// some time trying them first. This improves user privacy by
// creating fewer identifying DNS requests, reduces trust by
// giving seeds less influence on the network topology, and
// reduces traffic to the seeds.
// * When querying DNS seeds query a few at once, this ensures
// that we don't give DNS seeds the ability to eclipse nodes
// that query them.
// * If we continue having problems, eventually query all the
// DNS seeds, and if that fails too, also try the fixed seeds.
// (done in ThreadOpenConnections)
int found = 0;
const std::chrono::seconds seeds_wait_time = (addrman.Size() >= DNSSEEDS_DELAY_PEER_THRESHOLD ? DNSSEEDS_DELAY_MANY_PEERS : DNSSEEDS_DELAY_FEW_PEERS);

for (const std::string& seed : seeds) {
if (seeds_right_now == 0) {
seeds_right_now += DNSSEEDS_TO_QUERY_AT_ONCE;

if (addrman.Size() > 0) {
LogPrintf("Waiting %d seconds before querying DNS seeds.\n", seeds_wait_time.count());
std::chrono::seconds to_wait = seeds_wait_time;
while (to_wait.count() > 0) {
// if sleeping for the MANY_PEERS interval, wake up
// early to see if we have enough peers and can stop
// this thread entirely freeing up its resources
std::chrono::seconds w = std::min(DNSSEEDS_DELAY_FEW_PEERS, to_wait);
if (!interruptNet.sleep_for(w)) return;
to_wait -= w;

if (GetFullOutboundConnCount() >= target_outbound_connections) {
if (found > 0) {
LogPrintf("%d addresses found from DNS seeds\n", found);
LogPrintf("P2P peers available. Finished DNS seeding.\n");
} else {
LogPrintf("P2P peers available. Skipped DNS seeding.\n");
}
return;
}
}
if (nRelevant >= 2) {
if (found > 0) {
LogPrintf("%d addresses found from DNS seeds\n", found);
LogPrintf("P2P peers available. Finished DNS seeding.\n");
} else {
LogPrintf("P2P peers available. Skipped DNS seeding.\n");
}
return;
}
}
}
}

if (interruptNet) return;

// hold off on querying seeds if P2P network deactivated
if (!fNetworkActive) {
LogPrintf("Waiting for network to be reactivated before querying DNS seeds.\n");
do {
if (!interruptNet.sleep_for(std::chrono::seconds{1})) return;
} while (!fNetworkActive);
}
if (interruptNet) return;

LogPrintf("Loading addresses from DNS seed %s\n", seed);
// If -proxy is in use, we make an ADDR_FETCH connection to the DNS resolved peer address
// for the base dns seed domain in chainparams
if (HaveNameProxy()) {
AddAddrFetch(seed);
} else {
std::vector<CAddress> vAdd;
constexpr ServiceFlags requiredServiceBits{SeedsServiceFlags()};
std::string host = strprintf("x%x.%s", requiredServiceBits, seed);
CNetAddr resolveSource;
if (!resolveSource.SetInternal(host)) {
continue;
// hold off on querying seeds if P2P network deactivated
if (!fNetworkActive) {
LogPrintf("Waiting for network to be reactivated before querying DNS seeds.\n");
do {
if (!interruptNet.sleep_for(std::chrono::seconds{1})) return;
} while (!fNetworkActive);
}
unsigned int nMaxIPs = 256; // Limits number of IPs learned from a DNS seed
const auto addresses{LookupHost(host, nMaxIPs, true)};
if (!addresses.empty()) {
for (const CNetAddr& ip : addresses) {
CAddress addr = CAddress(CService(ip, m_params.GetDefaultPort()), requiredServiceBits);
addr.nTime = rng.rand_uniform_delay(Now<NodeSeconds>() - 3 * 24h, -4 * 24h); // use a random age between 3 and 7 days old
vAdd.push_back(addr);
found++;
}
addrman.Add(vAdd, resolveSource);
} else {
// If the seed does not support a subdomain with our desired service bits,
// we make an ADDR_FETCH connection to the DNS resolved peer address for the
// base dns seed domain in chainparams

LogPrintf("Loading addresses from DNS seed %s\n", seed);
// If -proxy is in use, we make an ADDR_FETCH connection to the DNS resolved peer address
// for the base dns seed domain in chainparams
if (HaveNameProxy()) {
AddAddrFetch(seed);
} else {
std::vector<CAddress> vAdd;
constexpr ServiceFlags requiredServiceBits{SeedsServiceFlags()};
std::string host = strprintf("x%x.%s", requiredServiceBits, seed);
CNetAddr resolveSource;
if (!resolveSource.SetInternal(host)) {
continue;
}
unsigned int nMaxIPs = 256; // Limits number of IPs learned from a DNS seed
const auto addresses{LookupHost(host, nMaxIPs, true)};
if (!addresses.empty()) {
for (const CNetAddr& ip : addresses) {
CAddress addr = CAddress(CService(ip, m_params.GetDefaultPort()), requiredServiceBits);
addr.nTime = rng.rand_uniform_delay(Now<NodeSeconds>() - 3 * 24h, -4 * 24h); // use a random age between 3 and 7 days old
vAdd.push_back(addr);
found++;
}
addrman.Add(vAdd, resolveSource);
} else {
// If the seed does not support a subdomain with our desired service bits,
// we make an ADDR_FETCH connection to the DNS resolved peer address for the
// base dns seed domain in chainparams
AddAddrFetch(seed);
}
}
--seeds_right_now;
}
--seeds_right_now;
LogPrintf("%d addresses found from DNS seeds\n", found);
} else {
LogPrintf("Skipping DNS seeds. Enough peers have been found\n");
}
LogPrintf("%d addresses found from DNS seeds\n", found);
}

void CConnman::DumpAddresses()
Expand Down Expand Up @@ -2343,6 +2365,19 @@ void CConnman::StartExtraBlockRelayPeers()
m_start_extra_block_relay_peers = true;
}

// Return the number of outbound connections that are full relay (not blocks only)
int CConnman::GetFullOutboundConnCount() const
{
int nRelevant = 0;
{
LOCK(m_nodes_mutex);
for (const CNode* pnode : m_nodes) {
if (pnode->fSuccessfullyConnected && pnode->IsFullOutboundConn()) ++nRelevant;
}
}
return nRelevant;
}

// Return the number of peers we have over our outbound connection limit
// Exclude peers that are marked for disconnect, or are going to be
// disconnected soon (eg ADDR_FETCH and FEELER)
Expand Down
2 changes: 2 additions & 0 deletions src/net.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1174,6 +1174,8 @@ class CConnman

void StartExtraBlockRelayPeers();

// Count the number of full-relay peer we have.
int GetFullOutboundConnCount() const;
// Return the number of outbound peers we have in excess of our target (eg,
// if we previously called SetTryNewOutboundPeer(true), and have since set
// to false, we may have extra peers that we wish to disconnect). This may
Expand Down

0 comments on commit 206094a

Please sign in to comment.