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packet.go
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packet.go
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package native
import (
"bufio"
"errors"
"io"
)
type pktReader struct {
rd *bufio.Reader
seq *byte
remain int
last bool
}
func (my *Conn) newPktReader() *pktReader {
return &pktReader{rd: my.rd, seq: &my.seq}
}
func (pr *pktReader) Read(buf []byte) (num int, err error) {
if len(buf) == 0 {
return 0, nil
}
defer catchError(&err)
if pr.remain == 0 {
// No data to read from current packet
if pr.last {
// No more packets
return 0, io.EOF
}
// Read next packet header
pr.remain = int(readU24(pr.rd))
seq := readByte(pr.rd)
// Chceck sequence number
if *pr.seq != seq {
return 0, SEQ_ERROR
}
*pr.seq++
// Last packet?
pr.last = (pr.remain != 0xffffff)
}
// Reading data
if len(buf) <= pr.remain {
num, err = pr.rd.Read(buf)
} else {
num, err = pr.rd.Read(buf[0:pr.remain])
}
pr.remain -= num
return
}
func (pr *pktReader) readAll() (buf []byte) {
buf = make([]byte, pr.remain)
nn := 0
for {
readFull(pr, buf[nn:])
if pr.last {
break
}
// There is next packet to read
new_buf := make([]byte, len(buf)+pr.remain)
copy(new_buf[nn:], buf)
nn += len(buf)
buf = new_buf
}
return
}
func (pr *pktReader) unreadByte() {
if err := pr.rd.UnreadByte(); err != nil {
panic(err)
}
pr.remain++
}
func (pr *pktReader) eof() bool {
return pr.remain == 0 && pr.last
}
func (pr *pktReader) checkEof() {
if !pr.eof() {
panic(PKT_LONG_ERROR)
}
}
type pktWriter struct {
wr *bufio.Writer
seq *byte
remain int
to_write int
last bool
}
func (my *Conn) newPktWriter(to_write int) *pktWriter {
return &pktWriter{wr: my.wr, seq: &my.seq, to_write: to_write}
}
/*func writePktHeader(wr io.Writer, seq byte, pay_len int) {
writeU24(wr, uint32(pay_len))
writeByte(wr, seq)
}*/
func (pw *pktWriter) Write(buf []byte) (num int, err error) {
if len(buf) == 0 {
return
}
defer catchError(&err)
var nn int
for len(buf) != 0 {
if pw.remain == 0 {
if pw.to_write == 0 {
err = errors.New("too many data for write as packet")
return
}
if pw.to_write >= 0xffffff {
pw.remain = 0xffffff
} else {
pw.remain = pw.to_write
pw.last = true
}
pw.to_write -= pw.remain
// Write packet header
writeU24(pw.wr, uint32(pw.remain))
writeByte(pw.wr, *pw.seq)
// Update sequence number
*pw.seq++
}
nn = len(buf)
if nn > pw.remain {
nn = pw.remain
}
nn, err = pw.wr.Write(buf[0:nn])
num += nn
pw.remain -= nn
if err != nil {
return
}
buf = buf[nn:]
}
if pw.remain+pw.to_write == 0 {
if !pw.last {
// Write header for empty packet
writeU24(pw.wr, 0)
writeByte(pw.wr, *pw.seq)
// Update sequence number
*pw.seq++
}
// Flush bufio buffers
err = pw.wr.Flush()
}
return
}