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|
package tftp
import (
"encoding/binary"
"fmt"
"io"
"net"
)
// the struct embedded into sender{} as sendA
type senderAnticipate struct {
enabled bool
winsz uint /* init windows size in number of buffers */
num uint /* actual packets to send. */
sends [][]byte /* buffers for a number of packets */
sendslens []uint /* data lens in buffers */
}
const anticipateWindowDefMax = 60 /* 60 by 512 is about 30k */
const anticipateDebug bool = false
func sendAInit(sA *senderAnticipate, ln uint, winSz uint) {
var ksz uint
if winSz > anticipateWindowDefMax {
ksz = anticipateWindowDefMax
} else if winSz < 2 {
ksz = 2
} else {
ksz = winSz
}
sA.sends = make([][]byte, ksz)
sA.sendslens = make([]uint, ksz)
for k := uint(0); k < ksz; k++ {
sA.sends[k] = make([]byte, ln)
sA.sendslens[k] = 0
}
sA.winsz = ksz
//fmt.Printf(" Set packet buffer size %v\n", ln)
}
// derived from ReadFrom()
func readFromAnticipate(s *sender, r io.Reader) (n int64, err error) {
s.block = 1 // start data transmission with block 1
ksz := uint(len(s.sendA.sends))
for k := uint(0); k < ksz; k++ {
binary.BigEndian.PutUint16(s.sendA.sends[k][0:2], opDATA)
s.sendA.sendslens[k] = 0
}
s.sendA.num = 0
for {
nx := int64(0)
knum := uint(0)
kfillOk := true /* default ok */
kfillPartial := false
for k := uint(0); k < ksz; k++ {
lx, err := io.ReadFull(r, s.sendA.sends[k][4:])
nx += int64(lx)
if err != nil && err != io.ErrUnexpectedEOF {
if err == io.EOF {
if kfillPartial {
break /* short packet already sent in last loop */
}
binary.BigEndian.PutUint16(s.sendA.sends[k][2:4],
s.block+uint16(k))
s.sendA.sendslens[k] = 4
knum = k + 1
kfillPartial = true
break
}
kfillOk = false
break /* fail */
} else if err != nil /* has to be io.ErrUnexpectedEOF now */ {
kfillPartial = true /* set the flag and send the packet */
}
binary.BigEndian.PutUint16(s.sendA.sends[k][2:4],
s.block+uint16(k))
s.sendA.sendslens[k] = uint(4 + lx)
knum = k + 1
}
if !kfillOk {
s.abort(err)
return n, err
}
s.sendA.num = knum
n += int64(nx)
if anticipateDebug {
fmt.Printf(" **** sends s.block %v pkts %v ", s.block, knum)
for k := uint(0); k < ksz; k++ {
fmt.Printf(" %v ", s.sendA.sendslens[k])
}
fmt.Println("")
}
_, err = s.sendWithRetryAnticipate()
if err != nil {
s.abort(err)
return n, err
}
if kfillPartial {
s.conn.close()
return n, nil
}
s.block += uint16(knum)
}
}
// derived from sendWithRetry()
func (s *sender) sendWithRetryAnticipate() (*net.UDPAddr, error) {
s.retry.reset()
for {
addr, err := s.sendDatagramAnticipate()
if _, ok := err.(net.Error); ok && s.retry.count() < s.retries {
s.retry.backoff()
continue
}
return addr, err
}
}
// derived from sendDatagram()
func (s *sender) sendDatagramAnticipate() (*net.UDPAddr, error) {
err1 := s.conn.setDeadline(s.timeout)
if err1 != nil {
return nil, err1
}
var err error
ksz := uint(len(s.sendA.sends))
knum := s.sendA.num
if knum > ksz {
err = fmt.Errorf("knum %v bigger than ksz %v", knum, ksz)
return nil, err
}
for k := uint(0); k < knum; k++ {
lx := s.sendA.sendslens[k]
if lx < 4 {
err = fmt.Errorf("lx smaller than 4")
break
}
errx := s.conn.sendTo(s.sendA.sends[k][:lx], s.addr)
if errx != nil {
err = fmt.Errorf("k %v errx %v", k, errx.Error())
break
}
}
if err != nil {
return nil, err
}
k := uint(0)
for {
n, addr, err := s.conn.readFrom(s.receive)
if err != nil {
return nil, err
}
if !addr.IP.Equal(s.addr.IP) || (s.tid != 0 && addr.Port != s.tid) {
continue
}
p, err := parsePacket(s.receive[:n])
if err != nil {
continue
}
s.tid = addr.Port
switch p := p.(type) {
case pACK:
if anticipateDebug {
fmt.Printf(" **** pACK p.block %v s.block %v k %v\n",
p.block(), s.block, k)
}
if p.block() == s.block+uint16(k) {
k++
if k == knum {
return addr, nil
}
}
case pOACK:
opts, err := unpackOACK(p)
if s.block != 0 {
continue
}
if err != nil {
s.abort(err)
return addr, err
}
for name, value := range opts {
if name == "blksize" {
err := s.setBlockSize(value)
if err != nil {
continue
}
}
}
return addr, nil
case pERROR:
return nil, fmt.Errorf("sending block %d: code=%d, error: %s",
s.block, p.code(), p.message())
}
}
}
|
