Add Read function

pcap.go

@@ -15,20 +15,13 @@ const MAXFRAME = 9000
 const LINKTYPE_ETHERNET = 1
 const LINKTYPE_RAW = 101
 
-type Frame struct {
-	ts time.Time
-	caplen uint32
-	framelen uint32
-	payload string
-}
-
 type FileHeader struct {
 	VersionMajor uint16
 	VersionMinor uint16
 	ThisZone int32
 	SigFigs uint32
-	SnapLen int32
+	SnapLen uint32
-	LinkType int32
+	LinkType uint32
 }
 
 type PcapFile struct {
@@ -36,6 +29,17 @@ type PcapFile struct {
 	header FileHeader
 }
 
+type FrameHeader struct {
+	ts time.Time
+	caplen uint32
+	framelen uint32
+}
+
+type Frame struct {
+	FrameHeader
+	payload []byte
+}
+
 type Reader struct {
 	PcapFile
 	r io.Reader
@@ -67,6 +71,26 @@ func NewReader(r io.Reader) (*Reader, error) {
 	return ret, nil
 }
 
+func (r *Reader) Read() (*Frame, error) {
+	var h FrameHeader
+
+	if err := binary.Read(r.r, r.order, &h); err != nil {
+		return nil, err
+	}
+
+	payload := make([]byte, h.caplen)
+	l, err := r.r.Read(payload)
+	if err != nil {
+		return nil, err
+	}
+	if uint32(l) < h.caplen {
+		return nil, fmt.Errorf("Short read: %d (wanted %d)", l, h.caplen)
+	}
+
+	ret := &Frame{h, payload}
+	return ret, nil
+}
+
 func main() {
 	r, err := NewReader(os.Stdin)
 	if err != nil {