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udp.go
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udp.go
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// Copyright (C) 2020 - 2023 iDigitalFlame
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <https://www.gnu.org/licenses/>.
//
package com
import (
"context"
"io"
"net"
"sync"
"time"
"github.com/iDigitalFlame/xmt/util/bugtrack"
)
const (
udpLimit = 4096
readOp = time.Microsecond * 15
writeOp = time.Microsecond * 35
)
var (
empty time.Time
udpWake struct{}
udpDeadline = new(udpErr)
buffers = sync.Pool{
New: func() interface{} {
var b [udpLimit]byte
return &b
},
}
)
type udpErr struct{}
type udpConn struct {
bufs chan udpData
sock *udpListener
wake chan struct{}
dev udpAddr
buf []byte
read, write time.Duration
lock sync.Mutex
}
type udpData struct {
_ [0]func()
b *[udpLimit]byte
n int
}
type udpCompat struct {
udpSock
}
type udpStream struct {
net.Conn
buf []byte
size int
fails uint8
read, write time.Duration
}
type udpSock interface {
udpSockInternal
net.PacketConn
}
type udpListener struct {
err error
ctx context.Context
del chan udpAddr
new chan *udpConn
cons map[udpAddr]*udpConn
sock *udpCompat
cancel context.CancelFunc
deadline time.Duration
lock sync.RWMutex
}
type udpConnector struct {
net.Dialer
}
func (udpErr) Timeout() bool {
return true
}
func (udpErr) Error() string {
return context.DeadlineExceeded.Error()
}
func (l *udpListener) purge() {
for {
select {
case d := <-l.del:
l.lock.Lock()
if c, ok := l.cons[d]; ok {
delete(l.cons, d)
close(c.bufs)
close(c.wake)
c.bufs, c.wake, c.sock = nil, nil, nil
c.lock.Unlock()
}
l.lock.Unlock()
case <-l.ctx.Done():
return
}
}
}
func (udpErr) Temporary() bool {
return true
}
func (l *udpListener) listen() {
loop:
for l.sock.SetReadDeadline(empty); ; l.sock.SetReadDeadline(empty) {
var (
b = buffers.Get().(*[udpLimit]byte)
n, a, err = l.sock.ReadPacket((*b)[:])
)
if bugtrack.Enabled {
bugtrack.Track("com.(*udpListener).listen(): Accept n=%d, a=%s, err=%s", n, a, err)
}
select {
case <-l.ctx.Done():
buffers.Put(b)
break loop
default:
if err != nil && !a.IsValid() && n == 0 {
buffers.Put(b)
l.err = err
break loop
}
if n == 0 || !a.IsValid() {
buffers.Put(b)
continue loop
}
}
if !a.IsValid() {
buffers.Put(b)
continue
}
l.lock.RLock()
c, ok := l.cons[a]
if l.lock.RUnlock(); ok {
if c.lock.Lock(); c.bufs != nil {
if bugtrack.Enabled {
bugtrack.Track("com.(*udpListener).listen(): Pushing n=%d bytes to conn a=%s", n, a.String())
}
c.bufs <- udpData{n: n, b: b}
c.lock.Unlock()
continue
}
c.lock.Unlock()
c = nil
}
if bugtrack.Enabled {
bugtrack.Track("com.(*udpListener).listen(): New tracked conn a=%s", a.String())
}
c = &udpConn{dev: a, sock: l, bufs: make(chan udpData, 256), wake: make(chan struct{}, 1)}
c.append(n, b, false)
go c.receive(l.ctx)
l.lock.Lock()
l.cons[a] = c
l.lock.Unlock()
l.new <- c
}
l.cancel()
if err := l.sock.Close(); err != nil && l.err == nil {
l.err = err
}
l.lock.Lock()
for _, c := range l.cons {
c.Close()
}
l.lock.Unlock()
close(l.del)
close(l.new)
l.cons = nil
}
func (c *udpConn) Close() error {
if c.sock == nil {
return nil
}
c.lock.Lock()
c.sock.del <- c.dev
c.sock = nil
return nil
}
func (udpAddr) Network() string {
return NameUDP
}
func (s *udpStream) Close() error {
err := s.Conn.Close()
s.read, s.write = -1, -1
return err
}
func (l *udpListener) Close() error {
err := l.sock.Close()
l.cancel()
return err
}
func (l *udpListener) Addr() net.Addr {
return l.sock.LocalAddr()
}
func (c *udpConn) LocalAddr() net.Addr {
return c.dev
}
// NewUDP creates a new simple UDP based connector with the supplied timeout.
func NewUDP(t time.Duration) Connector {
if t < 0 {
t = DefaultTimeout
}
return &udpConnector{Dialer: net.Dialer{Timeout: t, KeepAlive: t}}
}
func (s *udpStream) readEnough() error {
if s.read > 0 {
return s.readEnoughTimeout(s.read, 25)
}
if s.size > 0 {
if bugtrack.Enabled {
bugtrack.Track("com.(*udpStream).readEnough(): Implementing our own timeout for a Read operation.")
}
return s.readEnoughTimeout(time.Millisecond*500, 25)
}
return s.readEnoughTimeout(time.Second*2, 2)
}
func (c *udpConn) RemoteAddr() net.Addr {
return c.dev
}
func (c *udpConn) receive(x context.Context) {
for {
select {
case <-x.Done():
return
case p, ok := <-c.bufs:
if !ok {
return
}
c.append(p.n, p.b, true)
}
}
}
func (c *udpConn) Read(b []byte) (int, error) {
if len(c.buf) == 0 && c.bufs == nil {
if bugtrack.Enabled {
bugtrack.Track("com.(*udpCon).Read(): read on closed conn.")
}
return 0, io.ErrClosedPipe
}
var (
t *time.Timer
n int
w <-chan time.Time
err error
)
loop:
for n < len(b) {
if bugtrack.Enabled {
bugtrack.Track("com.(*udpCon).Read(): n=%d, len(b)=%d, len(c.buf)=%d", n, len(b), len(c.buf))
}
if len(c.buf) > 0 {
c.lock.Lock()
v := copy(b[n:], c.buf)
if bugtrack.Enabled {
bugtrack.Track("com.(*udpCon).Read(): n=%d, v=%d, len(b)=%d, len(c.buf)=%d", n, v, len(b), len(c.buf))
}
if c.buf = c.buf[v:]; len(c.buf) == 0 {
c.buf = nil
}
c.lock.Unlock()
n += v
continue
}
if n == 0 {
if c.bufs == nil {
err = io.EOF
break
}
if t != nil {
t.Stop()
t, w = nil, nil
}
if c.read > 0 {
t = time.NewTimer(c.read)
w = t.C
}
select {
case <-w:
err = udpDeadline
break loop
case <-c.wake:
continue loop
case <-c.sock.ctx.Done():
err = io.ErrClosedPipe
break loop
}
}
break
}
if t != nil {
t.Stop()
}
if bugtrack.Enabled {
bugtrack.Track("com.(*udpCon).Read(): return n=%d, err=%s", n, err)
}
return n, err
}
func (c *udpConn) Write(b []byte) (int, error) {
if c.sock == nil {
return 0, io.ErrShortWrite
}
var (
n int
t *time.Timer
w <-chan time.Time
err error
)
loop:
for v, s, x := 0, 0, udpLimit; n < len(b) && s < len(b); {
if t != nil {
t.Stop()
w, t = nil, nil
}
if x > len(b) {
x = len(b)
}
if c.write > 0 {
t = time.NewTimer(c.write)
if w = t.C; bugtrack.Enabled {
bugtrack.Track("com.(*udpCon).Write(): Created timer with duration c.write=%s, n=%d, len(b)=%d.", c.write, n, len(b))
}
}
v, err = c.sock.sock.WritePacket(b[s:x], c.dev)
if bugtrack.Enabled {
bugtrack.Track("com.(*udpCon).Write(): Wrote bytes out n=%d, len(b)=%d, s=%d, x=%d, v=%d.", n, len(b), s, x, v)
}
s += v
x += v
if n += v; err != nil {
break
}
select {
case <-w:
err = udpDeadline
break loop
case <-c.sock.ctx.Done():
err = io.ErrClosedPipe
break loop
default:
time.Sleep(writeOp)
}
}
if t != nil {
t.Stop()
}
return n, err
}
func (s *udpStream) Read(b []byte) (int, error) {
if s.size == 0 || s.size < len(b) {
if err := s.readEnough(); err != nil {
if bugtrack.Enabled {
bugtrack.Track("com.(*udpStream).Read(): readEnough() err=%s", err)
}
return 0, err
}
}
if bugtrack.Enabled {
bugtrack.Track("com.(*udpStream).Read(): Read s.size=%d, len(s.buf)=%d, len(b)=%d", s.size, len(s.buf), len(b))
}
n := copy(b, s.buf[:s.size])
s.buf = s.buf[n:]
if s.size -= n; s.size <= 0 {
s.buf = nil
}
if bugtrack.Enabled {
bugtrack.Track("com.(*udpStream).Read(): Post-read n=%d, s.size=%d, len(s.buf)=%d, len(b)=%d", n, s.size, len(s.buf), len(b))
}
return n, nil
}
func (s *udpStream) Write(b []byte) (int, error) {
var (
t *time.Timer
w <-chan time.Time
n int
err error
)
loop:
for e, c, x := 0, 0, udpLimit; n < len(b) && e < len(b); {
if t != nil {
t.Stop()
w, t = nil, nil
}
if x > len(b) {
x = len(b)
}
if s.write > 0 {
t = time.NewTimer(s.write)
w = t.C
s.Conn.SetWriteDeadline(time.Now().Add(s.write))
}
if c, err = s.Conn.Write(b[e:x]); bugtrack.Enabled {
bugtrack.Track("com.(*udpStream).Write(): e=%d, x=%d, c=%d, n=%d, len(b)=%d, err=%s", e, x, c, n, len(b), err)
}
e += c
x += c
if n += c; err != nil {
break loop
}
select {
case <-w:
err = udpDeadline
break loop
default:
time.Sleep(writeOp)
}
}
return n, err
}
func (c *udpConn) SetDeadline(t time.Time) error {
if t.IsZero() {
c.read, c.write = 0, 0
return nil
}
d := time.Until(t)
if d <= 0 {
c.read, c.write = 0, 0
return nil
}
c.read, c.write = d, d
return nil
}
func (l *udpListener) Accept() (net.Conn, error) {
var (
t *time.Timer
w <-chan time.Time
)
if l.deadline > 0 {
t = time.NewTimer(l.deadline)
w = t.C
}
loop:
for l.err == nil {
select {
case <-w:
return nil, udpDeadline
case n := <-l.new:
return n, nil
case <-l.ctx.Done():
break loop
}
}
if t != nil {
t.Stop()
}
return nil, l.err
}
func (s *udpStream) SetDeadline(t time.Time) error {
if t.IsZero() {
s.read, s.write = 0, 0
return s.Conn.SetDeadline(t)
}
d := time.Until(t)
if d <= 0 {
s.read, s.write = 0, 0
return s.Conn.SetDeadline(t)
}
s.read, s.write = d, d
return s.Conn.SetDeadline(t)
}
func (c *udpConn) SetReadDeadline(t time.Time) error {
if t.IsZero() {
c.read = 0
return nil
}
d := time.Until(t)
if d <= 0 {
c.read = 0
return nil
}
c.read = d
return nil
}
func (c *udpConn) SetWriteDeadline(t time.Time) error {
if t.IsZero() {
c.write = 0
return nil
}
d := time.Until(t)
if d <= 0 {
c.write = 0
return nil
}
c.write = d
return nil
}
func (s *udpStream) SetReadDeadline(t time.Time) error {
if t.IsZero() {
s.read = 0
return s.Conn.SetReadDeadline(t)
}
d := time.Until(t)
if d <= 0 {
s.read = 0
return s.Conn.SetReadDeadline(t)
}
s.read = d
return s.Conn.SetReadDeadline(t)
}
func (s *udpStream) SetWriteDeadline(t time.Time) error {
if t.IsZero() {
s.write = 0
return s.Conn.SetWriteDeadline(t)
}
d := time.Until(t)
if d <= 0 {
s.write = 0
return s.Conn.SetWriteDeadline(t)
}
s.write = d
return s.Conn.SetWriteDeadline(t)
}
func (c *udpConn) append(n int, b *[udpLimit]byte, w bool) {
if bugtrack.Enabled {
bugtrack.Track("com.(*udpCon).append(): n=%d, w=%t, len(c.buf)=%d", n, w, len(c.buf))
}
c.lock.Lock()
c.buf = append(c.buf, (*b)[:n]...)
c.lock.Unlock()
if buffers.Put(b); w {
select {
case c.wake <- udpWake:
if bugtrack.Enabled {
bugtrack.Track("com.(*udpCon).append(): Triggering wake.")
}
default:
}
}
}
func (s *udpStream) readEnoughTimeout(d time.Duration, m int) error {
var (
n int
err error
l = d // "Canary" value for timeout.
)
for q, y, c, k := d/time.Duration(m), time.Now().Add(d), 0, 0; ; {
if len(s.buf) == 0 || len(s.buf)-s.size < udpLimit {
if bugtrack.Enabled {
bugtrack.Track("com.(*udpStream).readEnoughTimeout(): Expanding socket buffer free=%d, len(s.buf)=%d, s.size=%d.", len(s.buf)-s.size, len(s.buf), s.size)
}
s.buf = append(s.buf, make([]byte, udpLimit)...)
}
if time.Sleep(readOp); bugtrack.Enabled {
bugtrack.Track("com.(*udpStream).readEnoughTimeout(): Pre-read s.size=%d, len(s.buf)=%d, q=%s, n=%d, d=%s, c=%d, s.fails=%d", s.size, len(s.buf), q, n, d, c, s.fails)
}
if s.read > 0 && l != s.read {
// When in channel mode, this is set by 'SetDeadline', which allows
// the writer Goroutine to "bump" the timeout on the reader and allow
// it to NOT get caught in an infinate read Op.
l, c, q, y = s.read, 0, s.read/time.Duration(m), time.Now().Add(s.read)
if bugtrack.Enabled {
bugtrack.Track("com.(*udpStream).readEnoughTimeout(): ReadDeadline was bumped to %s, c=0, q=%s", l, q)
}
}
s.Conn.SetReadDeadline(time.Now().Add(q))
if n, err = s.Conn.Read(s.buf[s.size:]); bugtrack.Enabled {
bugtrack.Track("com.(*udpStream).readEnoughTimeout(): Post-read n=%d, err=%s", n, err)
}
if s.size += n; s.read == -1 {
return io.ErrClosedPipe
}
if n > 0 || err == nil {
if k++; k > 1 {
return nil
}
continue
}
if e, ok := err.(net.Error); ok && e.Timeout() {
if time.Now().After(y) {
err = nil
if c++; c > m || s.size > 0 {
if bugtrack.Enabled {
bugtrack.Track("com.(*udpStream).readEnoughTimeout(): Read timeout hit, n=%d, s.size=%d, len(s.buf)=%d, c=%d, s.fails=%d", n, s.size, len(s.buf), c, s.fails)
}
break
}
continue
}
if c++; c > m {
err = nil
break
}
continue
}
if err == io.EOF {
err = nil
}
break
}
if bugtrack.Enabled {
bugtrack.Track("com.(*udpStream).readEnoughTimeout(): Read return n=%d, s.size=%d, len(s.buf)=%d, err=%s, s.fails=%d.", n, s.size, len(s.buf), err, s.fails)
}
if err != nil {
return err
}
if s.fails > 1 && s.size == 0 {
if bugtrack.Enabled {
bugtrack.Track("com.(*udpStream).readEnoughTimeout(): Fail count reached with no progress! s.fails=%d, s.size=%d.", s.fails, s.size)
}
return io.ErrNoProgress
}
if s.size == 0 {
if s.fails++; bugtrack.Enabled {
bugtrack.Track("com.(*udpStream).readEnoughTimeout(): Increasing fail count! s.fails=%d.", s.fails)
}
}
return nil
}
func (c *udpConnector) Connect(x context.Context, s string) (net.Conn, error) {
v, err := c.DialContext(x, NameUDP, s)
if err != nil {
return nil, err
}
return &udpStream{Conn: v}, nil
}
func (*udpConnector) Listen(x context.Context, s string) (net.Listener, error) {
c, err := ListenConfig.ListenPacket(x, NameUDP, s)
if err != nil {
return nil, err
}
l := &udpListener{
new: make(chan *udpConn, 16),
del: make(chan udpAddr, 16),
cons: make(map[udpAddr]*udpConn),
sock: &udpCompat{c.(*net.UDPConn)},
}
l.ctx, l.cancel = context.WithCancel(x)
go l.purge()
go l.listen()
return l, nil
}