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udp.go
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udp.go
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//go:build !no_udp_backend && !no_backends
// +build !no_udp_backend,!no_backends
package backends
import (
"context"
"crypto/tls"
"fmt"
"net"
"sync"
"time"
"github.com/distronode/receptor/pkg/logger"
"github.com/distronode/receptor/pkg/netceptor"
"github.com/distronode/receptor/pkg/utils"
"github.com/ghjm/cmdline"
)
// UDPMaxPacketLen is the maximum size of a message that can be sent over UDP.
const UDPMaxPacketLen = 65507
// UDPDialer implements Backend for outbound UDP.
type UDPDialer struct {
address string
redial bool
logger *logger.ReceptorLogger
}
func (b *UDPDialer) GetAddr() string {
return b.address
}
func (b *UDPDialer) GetTLS() *tls.Config {
return nil
}
// NewUDPDialer instantiates a new UDPDialer backend.
func NewUDPDialer(address string, redial bool, logger *logger.ReceptorLogger) (*UDPDialer, error) {
_, err := net.ResolveUDPAddr("udp", address)
if err != nil {
return nil, err
}
nd := UDPDialer{
address: address,
redial: redial,
logger: logger,
}
return &nd, nil
}
// Start runs the given session function over this backend service.
func (b *UDPDialer) Start(ctx context.Context, wg *sync.WaitGroup) (chan netceptor.BackendSession, error) {
return dialerSession(ctx, wg, b.redial, 5*time.Second, b.logger,
func(closeChan chan struct{}) (netceptor.BackendSession, error) {
dialer := net.Dialer{}
conn, err := dialer.DialContext(ctx, "udp", b.address)
if err != nil {
return nil, err
}
udpconn, ok := conn.(*net.UDPConn)
if !ok {
return nil, fmt.Errorf("DialContext returned a non-UDP connection")
}
ns := &UDPDialerSession{
conn: udpconn,
closeChan: closeChan,
closeChanCloser: sync.Once{},
}
return ns, nil
})
}
// UDPDialerSession implements BackendSession for UDPDialer.
type UDPDialerSession struct {
conn *net.UDPConn
closeChan chan struct{}
closeChanCloser sync.Once
}
// Send sends data over the session.
func (ns *UDPDialerSession) Send(data []byte) error {
if len(data) > UDPMaxPacketLen {
return fmt.Errorf("data too large")
}
n, err := ns.conn.Write(data)
if err != nil {
return err
}
if n != len(data) {
return fmt.Errorf("partial data sent")
}
return nil
}
// Recv receives data via the session.
func (ns *UDPDialerSession) Recv(timeout time.Duration) ([]byte, error) {
err := ns.conn.SetReadDeadline(time.Now().Add(timeout))
if err != nil {
return nil, err
}
buf := make([]byte, utils.NormalBufferSize)
n, err := ns.conn.Read(buf)
if nerr, ok := err.(net.Error); ok && nerr.Timeout() {
return nil, netceptor.ErrTimeout
}
if err != nil {
return nil, err
}
return buf[:n], nil
}
// Close closes the session.
func (ns *UDPDialerSession) Close() error {
if ns.closeChan != nil {
ns.closeChanCloser.Do(func() {
close(ns.closeChan)
ns.closeChan = nil
})
}
return ns.conn.Close()
}
// UDPListener implements Backend for inbound UDP.
type UDPListener struct {
laddr *net.UDPAddr
conn *net.UDPConn
sessChan chan *UDPListenerSession
sessRegLock sync.RWMutex
sessionRegistry map[string]*UDPListenerSession
logger *logger.ReceptorLogger
}
func (b *UDPListener) GetAddr() string {
return b.LocalAddr().String()
}
func (b *UDPListener) GetTLS() *tls.Config {
return &tls.Config{}
}
// NewUDPListener instantiates a new UDPListener backend.
func NewUDPListener(address string, logger *logger.ReceptorLogger) (*UDPListener, error) {
addr, err := net.ResolveUDPAddr("udp", address)
if err != nil {
return nil, err
}
uc, err := net.ListenUDP("udp", addr)
if err != nil {
return nil, err
}
ul := UDPListener{
laddr: addr,
conn: uc,
sessChan: make(chan *UDPListenerSession),
sessRegLock: sync.RWMutex{},
sessionRegistry: make(map[string]*UDPListenerSession),
logger: logger,
}
return &ul, nil
}
// LocalAddr returns the local address the listener is listening on.
func (b *UDPListener) LocalAddr() net.Addr {
if b.conn == nil {
return nil
}
return b.conn.LocalAddr()
}
// Start runs the given session function over the UDPListener backend.
func (b *UDPListener) Start(ctx context.Context, wg *sync.WaitGroup) (chan netceptor.BackendSession, error) {
sessChan := make(chan netceptor.BackendSession)
wg.Add(1)
go func() {
defer wg.Done()
buf := make([]byte, utils.NormalBufferSize)
for {
select {
case <-ctx.Done():
_ = b.conn.Close()
return
default:
}
err := b.conn.SetReadDeadline(time.Now().Add(1 * time.Second))
if err != nil {
b.logger.Error("Error setting UDP timeout: %s\n", err)
return
}
n, addr, err := b.conn.ReadFromUDP(buf)
if ne, ok := err.(net.Error); ok && ne.Timeout() {
continue
}
if err != nil {
b.logger.Error("UDP read error: %s\n", err)
return
}
data := make([]byte, n)
copy(data, buf)
addrStr := addr.String()
b.sessRegLock.RLock()
sess, ok := b.sessionRegistry[addrStr]
b.sessRegLock.RUnlock()
if !ok {
b.sessRegLock.Lock()
sess = &UDPListenerSession{
li: b,
raddr: addr,
recvChan: make(chan []byte),
}
b.sessionRegistry[addrStr] = sess
b.sessRegLock.Unlock()
select {
case <-ctx.Done():
_ = b.conn.Close()
return
case sessChan <- sess:
}
}
select {
case <-ctx.Done():
_ = b.conn.Close()
return
case sess.recvChan <- data:
}
}
}()
if b.conn != nil {
b.logger.Debug("Listening on UDP %s\n", b.LocalAddr().String())
}
return sessChan, nil
}
// UDPListenerSession implements BackendSession for UDPListener.
type UDPListenerSession struct {
li *UDPListener
raddr *net.UDPAddr
recvChan chan []byte
}
// Send sends data over the session.
func (ns *UDPListenerSession) Send(data []byte) error {
n, err := ns.li.conn.WriteToUDP(data, ns.raddr)
if err != nil {
return err
} else if n != len(data) {
return fmt.Errorf("partial data sent")
}
return nil
}
// Recv receives data from the session.
func (ns *UDPListenerSession) Recv(timeout time.Duration) ([]byte, error) {
select {
case data := <-ns.recvChan:
return data, nil
case <-time.After(timeout):
return nil, netceptor.ErrTimeout
}
}
// Close closes the session.
func (ns *UDPListenerSession) Close() error {
ns.li.sessRegLock.Lock()
defer ns.li.sessRegLock.Unlock()
delete(ns.li.sessionRegistry, ns.raddr.String())
return nil
}
// **************************************************************************
// Command line
// **************************************************************************
// TODO make these fields private
// UDPListenerCfg is the cmdline configuration object for a UDP listener.
type UDPListenerCfg struct {
BindAddr string `description:"Local address to bind to" default:"0.0.0.0"`
Port int `description:"Local UDP port to listen on" barevalue:"yes" required:"yes"`
Cost float64 `description:"Connection cost (weight)" default:"1.0"`
NodeCost map[string]float64 `description:"Per-node costs"`
AllowedPeers []string `description:"Peer node IDs to allow via this connection"`
}
func (cfg UDPListenerCfg) GetCost() float64 {
return cfg.Cost
}
func (cfg UDPListenerCfg) GetNodeCost() map[string]float64 {
return cfg.NodeCost
}
func (cfg UDPListenerCfg) GetAddr() string {
return cfg.BindAddr
}
func (cfg UDPListenerCfg) GetPort() int {
return cfg.Port
}
func (cfg UDPListenerCfg) GetTLS() string {
return ""
}
// Prepare verifies the parameters are correct.
func (cfg UDPListenerCfg) Prepare() error {
if cfg.Cost <= 0.0 {
return fmt.Errorf("connection cost must be positive")
}
for node, cost := range cfg.NodeCost {
if cost <= 0.0 {
return fmt.Errorf("connection cost must be positive for %s", node)
}
}
return nil
}
// Run runs the action.
func (cfg UDPListenerCfg) Run() error {
address := fmt.Sprintf("%s:%d", cfg.BindAddr, cfg.Port)
b, err := NewUDPListener(address, netceptor.MainInstance.Logger)
if err != nil {
netceptor.MainInstance.Logger.Error("Error creating listener %s: %s\n", address, err)
return err
}
err = netceptor.MainInstance.AddBackend(b,
netceptor.BackendConnectionCost(cfg.Cost),
netceptor.BackendNodeCost(cfg.NodeCost),
netceptor.BackendAllowedPeers(cfg.AllowedPeers))
if err != nil {
netceptor.MainInstance.Logger.Error("Error creating backend for %s: %s\n", address, err)
return err
}
return nil
}
// udpDialerCfg is the cmdline configuration object for a UDP listener.
type udpDialerCfg struct {
Address string `description:"Host:Port to connect to" barevalue:"yes" required:"yes"`
Redial bool `description:"Keep redialing on lost connection" default:"true"`
Cost float64 `description:"Connection cost (weight)" default:"1.0"`
AllowedPeers []string `description:"Peer node IDs to allow via this connection"`
}
// Prepare verifies the parameters are correct.
func (cfg udpDialerCfg) Prepare() error {
if cfg.Cost <= 0.0 {
return fmt.Errorf("connection cost must be positive")
}
return nil
}
// Run runs the action.
func (cfg udpDialerCfg) Run() error {
netceptor.MainInstance.Logger.Debug("Running UDP peer connection %s\n", cfg.Address)
b, err := NewUDPDialer(cfg.Address, cfg.Redial, netceptor.MainInstance.Logger)
if err != nil {
netceptor.MainInstance.Logger.Error("Error creating peer %s: %s\n", cfg.Address, err)
return err
}
err = netceptor.MainInstance.AddBackend(b,
netceptor.BackendConnectionCost(cfg.Cost),
netceptor.BackendAllowedPeers(cfg.AllowedPeers))
if err != nil {
netceptor.MainInstance.Logger.Error("Error creating backend for %s: %s\n", cfg.Address, err)
return err
}
return nil
}
func (cfg udpDialerCfg) PreReload() error {
return cfg.Prepare()
}
func (cfg UDPListenerCfg) PreReload() error {
return cfg.Prepare()
}
func (cfg udpDialerCfg) Reload() error {
return cfg.Run()
}
func (cfg UDPListenerCfg) Reload() error {
return cfg.Run()
}
func init() {
cmdline.RegisterConfigTypeForApp("receptor-backends",
"UDP-listener", "Run a backend listener on a UDP port", UDPListenerCfg{}, cmdline.Section(backendSection))
cmdline.RegisterConfigTypeForApp("receptor-backends",
"UDP-peer", "Make an outbound backend connection to a UDP peer", udpDialerCfg{}, cmdline.Section(backendSection))
}