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package main
import (
"bytes"
"crypto/hmac"
"crypto/sha256"
"crypto/tls"
"encoding/binary"
"flag"
"fmt"
"io"
"log"
"net"
"os"
"strconv"
"strings"
"time"
//BSD 3
uuid "github.com/satori/go.uuid"
)
const (
// Version Size
VERSION_SIZE = 1
// Type Size
TYPE_SIZE = 1
// UUID v4 Size
UUID_SIZE = 16
// Timestamp Size
TIMESTAMP_SIZE = 8
// HMAC-SHA256 MAC Size
HMAC_SIZE = 32
// Payload size Size
SSIZE = 4
HDR_SIZE = VERSION_SIZE + TYPE_SIZE + UUID_SIZE + HMAC_SIZE + TIMESTAMP_SIZE + SSIZE
)
type (
// A d4 writer implements the io.Writer Interface by implementing Write() and Close()
// it accepts an io.Writer as sink
d4Writer struct {
w io.Writer
key []byte
fb []byte
pb []byte
}
d4S struct {
src io.Reader
dst d4Writer
confdir string
d4error uint8
errnoCopy uint8
debug bool
conf d4params
}
d4params struct {
uuid []byte
snaplen uint32
key []byte
version uint8
source string
destination string
ttype uint8
}
)
var (
// verbose
buf bytes.Buffer
logger = log.New(&buf, "INFO: ", log.Lshortfile)
infof = func(info string) {
logger.Output(2, info)
}
confdir = flag.String("c", "", "configuration directory")
debug = flag.Bool("v", false, "Set to True, true, TRUE, 1, or t to enable verbose output on stdout")
)
func main() {
var d4 d4S
d4p := &d4
flag.Usage = func() {
fmt.Printf("d4 - d4 client\n")
fmt.Printf("Read data from the configured <source> and send it to <destination>\n")
fmt.Printf("\n")
fmt.Printf("Usage: d4 -c config_directory\n")
fmt.Printf("\n")
fmt.Printf("Configuration\n\n")
fmt.Printf("The configuration settings are stored in files in the configuration directory\n")
fmt.Printf("specified with the -c command line switch.\n\n")
fmt.Printf("Files in the configuration directory\n")
fmt.Printf("\n")
fmt.Printf("key - is the private HMAC-SHA-256-128 key.\n")
fmt.Printf(" The HMAC is computed on the header with a HMAC value set to 0\n")
fmt.Printf(" which is updated later.\n")
fmt.Printf("snaplen - the length of bytes that is read from the <source>\n")
fmt.Printf("version - the version of the d4 client\n")
fmt.Printf("type - the type of data that is send. pcap, netflow, ...\n")
fmt.Printf("source - the source where the data is read from\n")
fmt.Printf("destination - the destination where the data is written to\n")
fmt.Printf("\n")
fmt.Printf("-v [TRUE] for verbose output on stdout")
flag.PrintDefaults()
}
flag.Parse()
if flag.NFlag() == 0 || *confdir == "" {
flag.Usage()
os.Exit(1)
}
d4.confdir = *confdir
// Output logging before closing if debug is enabled
if *debug == true {
d4.debug = true
defer fmt.Print(&buf)
}
// TODO add flags for timeouts / fail on disconnect
c := make(chan string)
for {
if set(d4p) {
go d4Copy(d4p, c)
} else {
go func() {
time.Sleep(5 * time.Second)
fmt.Println("Sleeping.. before retry")
c <- "done waiting"
}()
}
<-c
}
}
func set(d4 *d4S) bool {
if d4loadConfig(d4) {
if setReaderWriters(d4) {
if d4.dst.initHeader(d4) {
return true
}
}
}
return false
}
func d4Copy(d4 *d4S, c chan string) {
_, err := io.CopyBuffer(&d4.dst, d4.src, d4.dst.pb)
if err != nil {
c <- fmt.Sprintf("%s", err)
}
}
func readConfFile(d4 *d4S, fileName string) []byte {
f, err := os.Open((*d4).confdir + "/" + fileName)
defer f.Close()
if err != nil {
log.Fatal(err)
}
data := make([]byte, 100)
count, err := f.Read(data)
if err != nil {
if err != io.EOF {
log.Fatal(err)
}
}
infof(fmt.Sprintf("read %d bytes: %q\n", count, data[:count]))
if err := f.Close(); err != nil {
log.Fatal(err)
}
// removes 1 for \n
return bytes.TrimSuffix(data[:count], []byte("\n"))
}
func d4loadConfig(d4 *d4S) bool {
// populate the map
(*d4).conf = d4params{}
(*d4).conf.source = string(readConfFile(d4, "source"))
(*d4).conf.destination = string(readConfFile(d4, "destination"))
tmpu, err := uuid.FromBytes(readConfFile(d4, "uuid"))
if err != nil {
// generate new uuid
(*d4).conf.uuid = generateUUIDv4()
// And push it into the conf file
f, err := os.OpenFile((*d4).confdir+"/uuid", os.O_WRONLY|os.O_CREATE, 0666)
defer f.Close()
if err != nil {
log.Fatal(err)
}
// store as canonical representation
f.WriteString(fmt.Sprintf("%s", uuid.FromBytesOrNil((*d4).conf.uuid)) + "\n")
} else {
(*d4).conf.uuid = tmpu.Bytes()
}
// parse snaplen to uint32
tmp, _ := strconv.ParseUint(string(readConfFile(d4, "snaplen")), 10, 32)
(*d4).conf.snaplen = uint32(tmp)
(*d4).conf.key = readConfFile(d4, "key")
// parse version to uint8
tmp, _ = strconv.ParseUint(string(readConfFile(d4, "version")), 10, 8)
(*d4).conf.version = uint8(tmp)
// parse type to uint8
tmp, _ = strconv.ParseUint(string(readConfFile(d4, "type")), 10, 8)
(*d4).conf.ttype = uint8(tmp)
return true
}
func newD4Writer(writer io.Writer, key []byte) d4Writer {
return d4Writer{w: writer, key: key}
}
// TODO QUICK IMPLEM, REVISE
func setReaderWriters(d4 *d4S) bool {
//TODO implement other destination file, fifo unix_socket ...
switch (*d4).conf.source {
case "stdin":
(*d4).src = os.Stdin
case "pcap":
f, _ := os.Open("capture.pcap")
(*d4).src = f
}
isn, dstnet := isNet((*d4).conf.destination)
if isn {
dial := net.Dialer{
DualStack: true,
Timeout: 5 * time.Second,
KeepAlive: 2 * time.Hour,
FallbackDelay: 0,
}
conn, errc := tls.DialWithDialer(&dial, "tcp", dstnet[0]+":"+dstnet[1], &tls.Config{InsecureSkipVerify: true})
if errc != nil {
return false
}
(*d4).dst = newD4Writer(conn, (*d4).conf.key)
} else {
switch (*d4).conf.destination {
case "stdout":
(*d4).dst = newD4Writer(os.Stdout, (*d4).conf.key)
case "file":
f, _ := os.Create("test.txt")
(*d4).dst = newD4Writer(f, (*d4).conf.key)
}
}
// Create the copy buffer
(*d4).dst.fb = make([]byte, HDR_SIZE+(*d4).conf.snaplen)
(*d4).dst.pb = make([]byte, (*d4).conf.snaplen)
return true
}
func isNet(d string) (bool, []string) {
ss := strings.Split(string(d), ":")
if len(ss) != 1 {
if net.ParseIP(ss[0]) != nil {
infof(fmt.Sprintf("Server IP: %s, Server Port: %s\n", ss[0], ss[1]))
return true, ss
}
}
return false, make([]string, 0)
}
func generateUUIDv4() []byte {
uuid, err := uuid.NewV4()
if err != nil {
log.Fatal(err)
}
infof(fmt.Sprintf("UUIDv4: %s\n", uuid))
return uuid.Bytes()
}
func (d4w *d4Writer) Write(bs []byte) (int, error) {
// bs is pb
// zero out moving parts of the frame
copy(d4w.fb[18:62], make([]byte, 44))
copy(d4w.fb[62:], make([]byte, 62+len(bs)))
// update headers
d4w.updateHeader(len(bs))
// Copy payload after the header
copy(d4w.fb[62:62+len(bs)], bs)
// Now that the packet is complete, compute hmac
d4w.updateHMAC(len(bs))
// Eventually write binary in the sink
err := binary.Write(d4w.w, binary.LittleEndian, d4w.fb[:62+len(bs)])
return len(bs), err
}
// TODO write go idiomatic err return values
func (d4w *d4Writer) updateHeader(lenbs int) bool {
timeUnix := time.Now().Unix()
binary.LittleEndian.PutUint64(d4w.fb[18:26], uint64(timeUnix))
binary.LittleEndian.PutUint32(d4w.fb[58:62], uint32(lenbs))
return true
}
func (d4w *d4Writer) updateHMAC(ps int) bool {
h := hmac.New(sha256.New, d4w.key)
h.Write(d4w.fb[0:1])
h.Write(d4w.fb[1:2])
h.Write(d4w.fb[2:18])
h.Write(d4w.fb[18:26])
h.Write(make([]byte, 32))
h.Write(d4w.fb[58:62])
h.Write(d4w.fb[62 : 62+ps])
copy(d4w.fb[26:58], h.Sum(nil))
return true
}
func (d4w *d4Writer) initHeader(d4 *d4S) bool {
// zero out the header
copy(d4w.fb[:HDR_SIZE], make([]byte, HDR_SIZE))
// put version a type into the header
d4w.fb[0] = (*d4).conf.version
d4w.fb[1] = (*d4).conf.ttype
// put uuid into the header
copy(d4w.fb[2:18], (*d4).conf.uuid)
// timestamp
timeUnix := time.Now().UnixNano()
binary.LittleEndian.PutUint64(d4w.fb[18:26], uint64(timeUnix))
// hmac is set to zero during hmac operations, so leave it alone
// init size of payload at 0
binary.LittleEndian.PutUint32(d4w.fb[58:62], uint32(0))
infof(fmt.Sprintf("Initialized a %d bytes header:\n", HDR_SIZE))
infof(fmt.Sprintf("%b\n", d4w.fb[:HDR_SIZE]))
return true
}