Implement the Writer interface + io.CopyBuffer
Jean-Louis Huynen
parent
066f29e8d1
commit
3d5feca4e7
126
d4-goclient.go
126
d4-goclient.go
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@ -39,10 +39,10 @@ type (
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// A d4 writer implements the io.Writer Interface by implementing Write() and Close()
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// it accepts an io.Writer as sink
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d4Writer struct {
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w io.Writer
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key []byte
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d4header []byte
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payload []byte
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w io.Writer
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key []byte
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fb []byte
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pb []byte
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}
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d4S struct {
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@ -122,7 +122,7 @@ func main() {
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if d4loadConfig(d4p) == true {
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if d4.dst.initHeader(d4p) == true {
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d4transfer(d4p)
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io.CopyBuffer(&d4.dst, d4.src, d4.dst.pb)
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}
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}
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}
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@ -202,6 +202,10 @@ func d4checkConfig(d4 *d4S) bool {
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f.Close()
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}
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// Create the copy buffer
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(*d4).dst.fb = make([]byte, HDR_SIZE+(*d4).conf.snaplen)
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(*d4).dst.pb = make([]byte, (*d4).conf.snaplen)
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return true
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}
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@ -214,107 +218,61 @@ func generateUUIDv4() []byte {
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return []byte(uuid[:])
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}
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func d4transfer(d4 *d4S) {
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src := (*d4).src
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dst := (*d4).dst
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buf := make([]byte, (*d4).conf.snaplen)
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varybuf := make([]byte, 0)
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for {
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// Take a slice of snaplen
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nread, err := src.Read(buf)
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if err != nil {
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// if EOF, we just wait for more data
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if err != io.EOF {
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log.Fatal(err)
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} else if (*d4).debug {
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os.Exit(0)
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}
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}
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// And push it into the d4writer -> sink chain
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switch {
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case uint32(nread) == (*d4).conf.snaplen:
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dst.Write(buf)
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case nread > 0 && uint32(nread) < (*d4).conf.snaplen:
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varybuf = append(buf[:nread])
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dst.Write(varybuf)
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}
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}
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}
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func (d4w *d4Writer) Write(bs []byte) (int, error) {
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d4w.updateHeader(bs)
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d4w.payload = bs
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d4w.updateHMAC()
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// bs is pb
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// zero out moving parts of the frame
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copy(d4w.fb[18:62], make([]byte, 44))
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copy(d4w.fb[62:], make([]byte, 62+len(bs)))
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// update headers
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d4w.updateHeader(len(bs))
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// Copy payload after the header
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copy(d4w.fb[62:62+len(bs)], bs)
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// Now that the packet is complete, compute hmac
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d4w.updateHMAC(len(bs))
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// Eventually write binary in the sink
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binary.Write(d4w.w, binary.LittleEndian, append(d4w.d4header, d4w.payload...))
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err := binary.Write(d4w.w, binary.LittleEndian, d4w.fb[:62+len(bs)])
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if err != nil {
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log.Fatal(err)
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}
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return len(bs), nil
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}
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// TODO write go idiomatic err return values
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func (d4w *d4Writer) updateHeader(bs []byte) bool {
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// zero out moving parts
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copy(d4w.d4header[18:], make([]byte, 44))
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func (d4w *d4Writer) updateHeader(lenbs int) bool {
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timeUnix := time.Now().Unix()
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ps := 18
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pe := ps + TIMESTAMP_SIZE
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binary.LittleEndian.PutUint64(d4w.d4header[ps:pe], uint64(timeUnix))
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// hmac is set to zero during hmac operations, so leave it alone
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// still, we move the pointers
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ps = pe
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pe = ps + HMAC_SIZE
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ps = pe
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pe = ps + 4
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// Set payload size
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binary.LittleEndian.PutUint32(d4w.d4header[ps:pe], uint32(len(bs)))
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binary.LittleEndian.PutUint64(d4w.fb[18:26], uint64(timeUnix))
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binary.LittleEndian.PutUint32(d4w.fb[58:62], uint32(lenbs))
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return true
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}
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func (d4w *d4Writer) updateHMAC() bool {
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func (d4w *d4Writer) updateHMAC(ps int) bool {
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h := hmac.New(sha256.New, d4w.key)
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// version
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h.Write(d4w.d4header[0:1])
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// type
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h.Write(d4w.d4header[1:2])
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// uuid
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h.Write(d4w.d4header[2:18])
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// timestamp
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h.Write(d4w.d4header[18:26])
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// hmac (0)
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h.Write(d4w.fb[0:1])
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h.Write(d4w.fb[1:2])
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h.Write(d4w.fb[2:18])
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h.Write(d4w.fb[18:26])
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h.Write(make([]byte, 32))
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// size
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h.Write(d4w.d4header[58:])
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// payload
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h.Write(d4w.payload)
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// final hmac
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copy(d4w.d4header[26:58], h.Sum(nil))
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h.Write(d4w.fb[58:62])
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h.Write(d4w.fb[62 : 62+ps])
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copy(d4w.fb[26:58], h.Sum(nil))
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return true
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}
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func (d4w *d4Writer) initHeader(d4 *d4S) bool {
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// zero out the header
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d4w.d4header = make([]byte, HDR_SIZE)
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copy(d4w.fb[:HDR_SIZE], make([]byte, HDR_SIZE))
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// put version a type into the header
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d4w.d4header[0] = (*d4).conf.version
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d4w.d4header[1] = (*d4).conf.ttype
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d4w.fb[0] = (*d4).conf.version
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d4w.fb[1] = (*d4).conf.ttype
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// put uuid into the header
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ps := 2
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pe := ps + UUID_SIZE
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copy(d4w.d4header[ps:pe], (*d4).conf.uuid)
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copy(d4w.fb[2:18], (*d4).conf.uuid)
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// timestamp
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timeUnix := time.Now().UnixNano()
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ps = pe
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pe = ps + TIMESTAMP_SIZE
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binary.LittleEndian.PutUint64(d4w.d4header[ps:pe], uint64(timeUnix))
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binary.LittleEndian.PutUint64(d4w.fb[18:26], uint64(timeUnix))
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// hmac is set to zero during hmac operations, so leave it alone
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// still, we move the pointers
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ps = pe
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pe = ps + HMAC_SIZE
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ps = pe
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pe = ps + 4
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// init size of payload at 0
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binary.LittleEndian.PutUint32(d4w.d4header[ps:pe], uint32(0))
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infof(fmt.Sprintf("Initialized a %d bytes header:\n", len(d4w.d4header)))
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infof(fmt.Sprintf("%b\n", d4w.d4header))
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binary.LittleEndian.PutUint32(d4w.fb[58:62], uint32(0))
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infof(fmt.Sprintf("Initialized a %d bytes header:\n", HDR_SIZE))
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infof(fmt.Sprintf("%b\n", d4w.fb[:HDR_SIZE]))
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return true
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}
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