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p2p: limit the number of incoming connections
to p2p.max_num_inbound_peers + len(p2p.unconditional_peer_ids)
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melekes authored and tessr committed Apr 9, 2020
1 parent ff87bd9 commit e2d6859
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Showing 3 changed files with 64 additions and 2 deletions.
5 changes: 5 additions & 0 deletions node/node.go
Expand Up @@ -471,6 +471,11 @@ func createTransport(
}

p2p.MultiplexTransportConnFilters(connFilters...)(transport)

// Limit the number of incoming connections.
max := config.P2P.MaxNumInboundPeers + len(splitAndTrimEmpty(config.P2P.UnconditionalPeerIDs, ",", " "))
p2p.MultiplexTransportMaxIncomingConnections(max)(transport)

return transport, peerFilters
}

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16 changes: 14 additions & 2 deletions p2p/transport.go
Expand Up @@ -7,6 +7,7 @@ import (
"time"

"github.com/pkg/errors"
"golang.org/x/net/netutil"

"github.com/tendermint/tendermint/crypto"
"github.com/tendermint/tendermint/p2p/conn"
Expand Down Expand Up @@ -122,11 +123,18 @@ func MultiplexTransportResolver(resolver IPResolver) MultiplexTransportOption {
return func(mt *MultiplexTransport) { mt.resolver = resolver }
}

// MultiplexTransportMaxIncomingConnections sets the maximum number of
// simultaneous connections (incoming). Default: 0 (unlimited)
func MultiplexTransportMaxIncomingConnections(n int) MultiplexTransportOption {
return func(mt *MultiplexTransport) { mt.maxIncomingConnections = n }
}

// MultiplexTransport accepts and dials tcp connections and upgrades them to
// multiplexed peers.
type MultiplexTransport struct {
netAddr NetAddress
listener net.Listener
netAddr NetAddress
listener net.Listener
maxIncomingConnections int // see MaxIncomingConnections

acceptc chan accept
closec chan struct{}
Expand Down Expand Up @@ -240,6 +248,10 @@ func (mt *MultiplexTransport) Listen(addr NetAddress) error {
return err
}

if mt.maxIncomingConnections > 0 {
ln = netutil.LimitListener(ln, mt.maxIncomingConnections)
}

mt.netAddr = addr
mt.listener = ln

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45 changes: 45 additions & 0 deletions p2p/transport_test.go
Expand Up @@ -5,6 +5,7 @@ import (
"math/rand"
"net"
"reflect"
"strings"
"testing"
"time"

Expand Down Expand Up @@ -134,6 +135,50 @@ func TestTransportMultiplexConnFilterTimeout(t *testing.T) {
}
}

func TestTransportMultiplexMaxIncomingConnections(t *testing.T) {
mt := newMultiplexTransport(
emptyNodeInfo(),
NodeKey{
PrivKey: ed25519.GenPrivKey(),
},
)
id := mt.nodeKey.ID()

MultiplexTransportMaxIncomingConnections(0)(mt)

addr, err := NewNetAddressString(IDAddressString(id, "127.0.0.1:0"))
if err != nil {
t.Fatal(err)
}

if err := mt.Listen(*addr); err != nil {
t.Fatal(err)
}

errc := make(chan error)

go func() {
addr := NewNetAddress(id, mt.listener.Addr())

_, err := addr.Dial()
if err != nil {
errc <- err
return
}

close(errc)
}()

if err := <-errc; err != nil {
t.Errorf("connection failed: %v", err)
}

_, err = mt.Accept(peerConfig{})
if err == nil || !strings.Contains(err.Error(), "connection reset by peer") {
t.Errorf("expected connection reset by peer error, got %v", err)
}
}

func TestTransportMultiplexAcceptMultiple(t *testing.T) {
mt := testSetupMultiplexTransport(t)
laddr := NewNetAddress(mt.nodeKey.ID(), mt.listener.Addr())
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