/
ringcap.go
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/
ringcap.go
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/*
* Ringcap - pcap ringbuffer
* Copyright (c) 2015 Shannon Wynter, Ladbrokes Digital Australia Pty Ltd.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* Author: Shannon Wynter <http://fremnet.net/contact>
*/
package main
import (
"flag"
"fmt"
"github.com/google/gopacket/pcap"
"github.com/google/gopacket/layers"
"github.com/op/go-logging"
"github.com/pivotal-golang/bytefmt"
"io"
"net"
"os"
"path"
"time"
)
var (
bindAddr = "127.0.0.1:4231"
dumpHost = "127.0.0.1:4231"
packetLimit = 10000
snapLen = 65535
iface = "eth0"
filter = ""
listener = false
savePath = ""
printVersion = false
)
var log = logging.MustGetLogger("ringcap")
func init() {
savePath, _ = os.Getwd()
flag.StringVar(&bindAddr, "bind-addr", bindAddr, "Address to bind to")
flag.StringVar(&dumpHost, "dump-host", dumpHost, "Host Address to dump to")
flag.IntVar(&packetLimit, "packet-limit", packetLimit, "Maximum packet count")
flag.IntVar(&snapLen, "snaplen", snapLen, "Maximum packet size in bytes")
flag.StringVar(&iface, "interface", iface, "interface to monitor")
flag.StringVar(&filter, "filter", filter, "Optional filter")
flag.BoolVar(&printVersion, "version", printVersion, "Display the current version")
flag.BoolVar(&listener, "listen", listener, "Listen for dumps")
flag.StringVar(&savePath, "save-path", savePath, "Where to store dumps (when listening)")
}
func initTrigger() (chan bool, error) {
ch := make(chan bool, 1)
addr, err := net.ResolveUDPAddr("udp4", bindAddr)
if err != nil {
return nil, err
}
conn, err := net.ListenUDP("udp4", addr)
if err != nil {
return nil, err
}
b := make([]byte, UDP_PACKET_SIZE)
go func() {
for {
_, _, err := conn.ReadFromUDP(b)
if err != nil {
log.Warning("%s", err)
continue
}
ch <- true
}
}()
return ch, nil
}
func runDumper() {
consoleBackend := logging.NewLogBackend(os.Stderr, "", 0)
syslogBackend, err := logging.NewSyslogBackend("")
if err != nil {
log.Fatal(err)
}
logging.SetBackend(consoleBackend, syslogBackend)
logging.SetFormatter(logging.MustStringFormatter("%{color}%{time:15:04:05.000000} ▶ %{level:.4s} %{id:03x}%{color:reset} %{message}"))
log := logging.MustGetLogger("main")
maxMemory := bytefmt.ByteSize(uint64(packetLimit * snapLen))
log.Info("Preparing to capture on %s with a buffer of %d and snaplen of %d - Maximum memory usage %s", iface, packetLimit, snapLen, maxMemory)
log.Info("On any udp packet sent to %s pcap formatted data will be sent to tcp://%s", bindAddr, dumpHost)
triggerChan, err := initTrigger()
if err != nil {
log.Fatal(err)
}
handle, err := pcap.OpenLive(iface, int32(snapLen), false, pcap.BlockForever)
if err != nil {
log.Fatal(err)
}
defer handle.Close()
if filter != "" {
log.Info("Using filter \"%s\"", filter)
if err := handle.SetBPFFilter(filter); err != nil { // optional
log.Fatal("Unable to compile and set filter: ", err)
}
}
pr := NewPacketRing(handle, handle.LinkType(), packetLimit)
go pr.Run()
for {
select {
case <-triggerChan:
sendDump(pr, handle.LinkType())
}
}
}
func sendDump(pr *PacketRing, linkType layers.LinkType) {
log.Info("Dumping %d captured packets to %s", pr.Count(), dumpHost)
conn, err := net.Dial("tcp", dumpHost)
if err != nil {
log.Error("Unable to connect to %s: %s", dumpHost, err)
return
}
defer conn.Close()
err = pr.WritePackets(conn, snapLen, linkType)
if err != nil {
log.Error("Failed to dump to %s: %s", dumpHost, err)
return
}
}
func handleDump(conn net.Conn) {
defer conn.Close()
remote := conn.RemoteAddr().(*net.TCPAddr)
remoteIP := remote.IP.String()
port := remote.Port
log.Info("Connection from %s:%d", remoteIP, port)
filename := path.Join(savePath, fmt.Sprintf("%s-%d-%d.pcap", remoteIP, time.Now().Unix(), port))
file, err := os.Create(filename)
if err != nil {
log.Error("Unable to create ", filename, ": ", err)
return
}
defer file.Close()
bytes, err := io.Copy(file, conn)
if err != nil {
log.Error("Problem saving dump to ", filename, ": ", err)
return
}
log.Info("Dump \"%s\" created - %s", path.Base(filename), bytefmt.ByteSize(uint64(bytes)))
}
func runListener() {
l, err := net.Listen("tcp4", bindAddr)
if err != nil {
log.Fatal("Error listening: ", err)
}
defer l.Close()
log.Info("Listening on %s for dumps", bindAddr)
for {
conn, err := l.Accept()
if err != nil {
log.Error("Error accepting: ", err)
continue
}
go handleDump(conn)
}
}
func main() {
flag.Parse()
if printVersion {
fmt.Printf("ringcap %s\n", VERSION)
os.Exit(0)
}
if listener {
runListener()
} else {
runDumper()
}
}