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Rate limit connections and enforce read deadline on handshake

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This commit is contained in:
Geoff Bourne 2019-07-08 19:07:36 -05:00
parent 9e64ab2ab2
commit 7c7f0e1b3c
1 changed files with 33 additions and 2 deletions
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35
server/connector.go
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@ -7,8 +7,16 @@ import (
"github.com/sirupsen/logrus"
"io"
"net"
"time"
)
const (
connectionsLimitPerSec = 1
handshakeTimeout = 30 * time.Second
)
var noDeadline time.Time
type IConnector interface {
StartAcceptingConnections(ctx context.Context, listenAddress string) error
}
@ -33,14 +41,17 @@ func (c *connectorImpl) StartAcceptingConnections(ctx context.Context, listenAdd
}
func (c *connectorImpl) acceptConnections(ctx context.Context, ln net.Listener) {
//noinspection GoUnhandledErrorResult
defer ln.Close()
limiter := time.Tick(time.Second / connectionsLimitPerSec)
for {
select {
case <-ctx.Done():
return
default:
case <-limiter:
conn, err := ln.Accept()
if err != nil {
logrus.WithError(err).Error("Failed to accept connection")
@ -52,6 +63,7 @@ func (c *connectorImpl) acceptConnections(ctx context.Context, ln net.Listener)
}
func (c *connectorImpl) HandleConnection(ctx context.Context, frontendConn net.Conn) {
//noinspection GoUnhandledErrorResult
defer frontendConn.Close()
clientAddr := frontendConn.RemoteAddr()
@ -61,6 +73,13 @@ func (c *connectorImpl) HandleConnection(ctx context.Context, frontendConn net.C
inspectionReader := io.TeeReader(frontendConn, inspectionBuffer)
if err := frontendConn.SetReadDeadline(time.Now().Add(handshakeTimeout)); err != nil {
logrus.
WithError(err).
WithField("client", frontendConn).
Error("Failed to set read deadline")
return
}
packet, err := mcproto.ReadPacket(inspectionReader, clientAddr)
if err != nil {
logrus.WithError(err).WithField("clientAddr", clientAddr).Error("Failed to read packet")
@ -106,13 +125,25 @@ func (c *connectorImpl) HandleConnection(ctx context.Context, frontendConn net.C
}
logrus.WithField("amount", amount).Debug("Relayed handshake to backend")
if err = frontendConn.SetReadDeadline(noDeadline); err != nil {
logrus.
WithError(err).
WithField("client", frontendConn).
Error("Failed to clear read deadline")
return
}
pumpConnections(ctx, frontendConn, backendConn)
} else {
logrus.WithField("packetID", packet.PacketID).Error("Unexpected packetID, expected handshake")
logrus.
WithField("client", frontendConn).
WithField("packetID", packet.PacketID).
Error("Unexpected packetID, expected handshake")
return
}
}
func pumpConnections(ctx context.Context, frontendConn, backendConn net.Conn) {
//noinspection GoUnhandledErrorResult
defer backendConn.Close()
errors := make(chan error, 2)