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udp.go
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udp.go
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// Copyright 2014 JPH <jph@hackworth.be>
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package main
import (
"github.com/sirupsen/logrus"
"net"
"os"
"syscall"
)
const (
UDP_MAX_PACKET_SIZE = 8192
UDP_PADDING = 512
UDP_MAX_PACKET_PAYLOAD = UDP_MAX_PACKET_SIZE - UDP_PADDING
)
func (c *ServerConfig) newUDPServer() *UDPServer {
u := new(UDPServer)
u.bufsz = UDP_MAX_PACKET_SIZE
u.padsz = UDP_PADDING
u.config = c
u.log = logrus.New()
//u.log.
u.log.Out = os.Stderr
u.log.Level = logrus.DebugLevel
return u
}
func (u *UDPServer) start() {
u.log.Debug("Starting UDP Interface on %s", u.config.Listen)
u.listen()
}
func (u *UDPServer) listen() {
localAddr, err := net.ResolveUDPAddr("udp4", u.config.Listen)
checkFatal(err)
u.conn, err = net.ListenUDP("udp4", localAddr)
checkFatal(err)
f, err := u.conn.File()
defer f.Close()
checkFatal(err)
fd := int(f.Fd())
// This one makes sure all packets we send out do not have DF set on them.
err = syscall.SetsockoptInt(fd, syscall.IPPROTO_IP, syscall.IP_MTU_DISCOVER, syscall.IP_PMTUDISC_DONT)
checkFatal(err)
u.log.Debug("UDPServer.listen(): going into read loop")
go u.readLoop()
}
func (u *UDPServer) readLoop() {
defer u.conn.Close()
payload := make([]byte, u.bufsz) // TODO: optimize
oob := make([]byte, 4096) // TODO: optimize
for {
n, oobn, _, _, err := u.conn.ReadMsgUDP(payload, oob)
u.log.Debug("UDPServer.readLoop(): payload[%d], oob[%d]", n, oobn)
checkFatal(err)
}
}