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udp.go
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udp.go
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/*
© 2021–present Harald Rudell <harald.rudell@gmail.com> (https://haraldrudell.github.io/haraldrudell/)
ISC License
*/
package pnet
import (
"net"
"sync"
"sync/atomic"
"github.com/haraldrudell/parl"
"github.com/haraldrudell/parl/perrors"
)
type UDP struct {
Network string
F UDPFunc
MaxSize int
net.UDPAddr // struct IP Port Zone
ListenInvoked atomic.Bool
StartingListen sync.WaitGroup
ErrCh chan<- error
IsListening atomic.Bool
NetUDPConn *net.UDPConn
connMutex sync.RWMutex
Addr net.Addr
IsShutdown atomic.Bool
}
type UDPFunc func(b []byte, oob []byte, flags int, addr *net.UDPAddr)
// NewUDP network: "udp" "udp4" "udp6" address: "host:port"
func NewUDP(network, address string, udpFunc UDPFunc, maxSize int) (udp *UDP) {
if maxSize < 1 {
maxSize = udpDefaultMaxSize
}
if netUDPAddr, err := net.ResolveUDPAddr(network, address); err != nil {
panic(perrors.Errorf("net.ResolveUDPAddr: '%w'", err))
} else {
udp = &UDP{UDPAddr: *netUDPAddr, Network: network, F: udpFunc, MaxSize: maxSize}
}
return
}
const (
udpDefaultMaxSize = 65507 // max for ipv4
oobSize = 40
netReadOperation = "read"
useOfClosed = "use of closed network connection"
)
func (udp *UDP) Listen() (errCh <-chan error) {
udp.StartingListen.Add(1)
if !udp.ListenInvoked.CompareAndSwap(false, true) {
udp.StartingListen.Done()
panic(perrors.New("multiple udp.Listen invocations"))
}
if udp.IsShutdown.Load() {
udp.StartingListen.Done()
panic(perrors.New("udp.Listen after Shutdown"))
}
errChan := make(chan error)
errCh = errChan
udp.ErrCh = errChan
go udp.listenThread()
return
}
func (udp *UDP) listenThread() {
errCh := udp.ErrCh
defer close(errCh)
var FInvocations sync.WaitGroup
defer FInvocations.Wait()
var startingDone bool
defer func() {
if !startingDone {
udp.StartingListen.Done()
}
}()
defer parl.Recover2(func() parl.DA { return parl.A() }, nil, func(e error) { errCh <- e }) // capture panics
// listen
var netUDPConn *net.UDPConn // represents a network file descriptor
var err error
if netUDPConn, err = net.ListenUDP(udp.Network, &udp.UDPAddr); err != nil {
errCh <- perrors.Errorf("net.ListenUDP: '%w'", err)
return
}
if udp.setConn(netUDPConn) { // isShutdown
if err = netUDPConn.Close(); err != nil {
errCh <- perrors.Errorf("netUDPConn.Close: '%w'", err)
}
return
}
udp.Addr = netUDPConn.LocalAddr()
udp.IsListening.Store(true)
udp.StartingListen.Done()
startingDone = true
defer func() {
if !udp.IsShutdown.Load() {
if err := netUDPConn.Close(); err != nil {
errCh <- err
}
}
udp.IsListening.Store(false)
}()
// read datagrams
for {
b := make([]byte, udp.MaxSize)
oob := make([]byte, oobSize)
var n int
var oobn int
var flags int
var addr *net.UDPAddr
var err error
n, oobn, flags, addr, err = netUDPConn.ReadMsgUDP(b, oob)
if err != nil {
if udp.IsShutdown.Load() && udp.isClosedErr(err) {
return // we are shutdown
}
errCh <- perrors.Errorf("ReadMsgUDP: '%w'", err)
return
}
FInvocations.Add(1)
go func() {
defer FInvocations.Done()
udp.F(b[:n], oob[:oobn], flags, addr)
}()
}
}
func (udp *UDP) WaitForUp() (isUp bool, addr net.Addr) {
if !udp.ListenInvoked.Load() {
return // Listen has not been invoked
}
udp.StartingListen.Wait()
if isUp = udp.IsListening.Load(); isUp {
addr = udp.Addr
}
return
}
func (udp *UDP) isClosedErr(err error) (isClose bool) {
// read udp 127.0.0.1:50050: use of closed network connection
// &net.OpError{Op:"read", Net:"udp", Source:(*net.UDPAddr)(0xc00007a030), Addr:net.Addr(nil), Err:(*errors.errorString)(0xc000098160)}
opErr, ok := err.(*net.OpError)
if !ok {
return
}
if opErr.Op != netReadOperation {
return
}
e := opErr.Err
// &errors.errorString{s:"use of closed network connection"}
if e.Error() != useOfClosed {
return // some other error
}
isClose = true
return
}
func (udp *UDP) setConn(conn *net.UDPConn) (isShutdown bool) {
udp.connMutex.Lock()
defer udp.connMutex.Unlock()
isShutdown = udp.IsShutdown.Load()
if !isShutdown {
udp.NetUDPConn = conn
}
return
}
func (udp *UDP) Shutdown() {
udp.connMutex.RLock()
defer udp.connMutex.RUnlock()
if !udp.IsShutdown.CompareAndSwap(false, true) {
return // it was already shutdown
}
conn := udp.NetUDPConn
if conn == nil {
return // no need to close connection
}
err := conn.Close()
if err == nil {
return // conn successfully closed
}
udp.ErrCh <- err
}