2019-11-30 19:08:12 +00:00
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package main
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import (
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2019-11-30 21:07:20 +00:00
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"bytes"
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"context"
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2019-11-30 19:08:12 +00:00
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"crypto/tls"
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"fmt"
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"io"
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"io/ioutil"
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"log"
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"math/rand"
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"net"
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"net/http"
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"os"
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"sync"
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"time"
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"github.com/hashicorp/yamux"
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"within.website/ln"
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"within.website/x/localca"
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)
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2019-11-30 21:07:20 +00:00
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// Config uration for the server.
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type Config struct {
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HTTPPort, HTTPSPort, YamuxPort, StatusPort, DomainSuffix string
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}
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2019-11-30 21:07:20 +00:00
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// F ields for logging.
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func (c Config) F() ln.F {
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return ln.F{
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"http-port": c.HTTPPort,
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"https-port": c.HTTPSPort,
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"yamux-port": c.YamuxPort,
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"status-port": c.StatusPort,
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"domain-suffix": c.DomainSuffix,
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}
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}
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// Server is the iconia gateway server.
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type Server struct {
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Config
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clients map[string][]*yamux.Session
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clientsLock *sync.RWMutex
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certManager localca.Manager
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plainServer, statusServer *http.Server
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tlsListener, yamuxListener net.Listener
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tokenInfo map[string]string
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tokensLock *sync.Mutex
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}
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func (s *Server) goAwayClients() {
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s.clientsLock.Lock()
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defer s.clientsLock.Unlock()
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for _, set := range s.clients {
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for _, sesh := range set {
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sesh.GoAway()
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}
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}
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}
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2019-12-01 13:52:44 +00:00
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func (s *Server) killClients() {
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s.clientsLock.RLock()
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defer s.clientsLock.RUnlock()
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for _, set := range s.clients {
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for _, sesh := range set {
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_ = sesh.Close()
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}
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}
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}
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func (s *Server) handleYamuxClientHello(chi *tls.ClientHelloInfo) (*tls.Config, error) {
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var found bool
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s.tokensLock.Lock()
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var token = s.tokenInfo[chi.ServerName]
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s.tokensLock.Unlock()
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for _, proto := range chi.SupportedProtos {
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if proto == token {
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found = true
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break
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}
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}
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if !found {
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return nil, fmt.Errorf("unknown token for domain %s", chi.ServerName)
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}
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2019-11-30 21:07:20 +00:00
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tc := &tls.Config{
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GetCertificate: s.certManager.GetCertificate,
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NextProtos: []string{token},
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ServerName: chi.ServerName,
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}
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return tc, nil
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}
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func gen502Page(host, why string) *http.Response {
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template := `<html><head><title>${WHY}</title></head><body><h1>${WHY}</h1><p>Please ensure a backend is running for ${HOST}.</p></body></html>`
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resbody := []byte(os.Expand(template, func(in string) string {
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switch in {
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case "HOST":
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return host
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case "WHY":
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return why
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}
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return "<unknown>"
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}))
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reshdr := http.Header{}
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reshdr.Set("Content-Type", "text/html; charset=utf-8")
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resp := &http.Response{
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Status: fmt.Sprintf("%d Bad Gateway", http.StatusBadGateway),
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StatusCode: http.StatusBadGateway,
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Body: ioutil.NopCloser(bytes.NewBuffer(resbody)),
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Proto: "HTTP/1.1",
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ProtoMajor: 1,
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ProtoMinor: 1,
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Header: reshdr,
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ContentLength: int64(len(resbody)),
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Close: true,
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Request: nil,
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}
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return resp
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}
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func (s *Server) yamuxHandler(l net.Listener) error {
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for {
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c, err := l.Accept()
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if err != nil {
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return err
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}
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go s.handleYamuxClient(c)
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}
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panic("unexpected state")
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}
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func (s *Server) handleYamuxClient(c net.Conn) {
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tlsConn, ok := c.(*tls.Conn)
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if !ok {
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panic("no, this should really be impossible")
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}
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tlsConn.Handshake()
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sName := tlsConn.ConnectionState().ServerName
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ctx := context.Background()
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ctx = ln.WithF(ctx, ln.F{
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"domain-name": sName,
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"remote-host": c.RemoteAddr().String(),
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})
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sesh, err := yamux.Server(c, &yamux.Config{
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AcceptBacklog: 1,
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EnableKeepAlive: true,
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KeepAliveInterval: time.Minute,
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ConnectionWriteTimeout: 100 * time.Millisecond,
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MaxStreamWindowSize: 262144 * 16,
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Logger: log.New(os.Stderr, sName+": ", log.LstdFlags),
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})
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if err != nil {
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ln.Error(ctx, err)
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c.Close()
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return
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}
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s.clientsLock.Lock()
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s.clients[sName] = append(s.clients[sName], sesh)
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i := len(s.clients[sName]) - 1
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s.clientsLock.Unlock()
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ln.Log(ctx, ln.Info("agent registered"))
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go func() {
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<-sesh.CloseChan()
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ln.Log(ctx, ln.Info("client closed"))
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s.clientsLock.Lock()
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s.clients[sName] = append(s.clients[sName][:i], s.clients[sName][i+1:]...)
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s.clientsLock.Unlock()
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}()
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}
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func (s *Server) tlsForward(l net.Listener) error {
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for {
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c, err := l.Accept()
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if err != nil {
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return fmt.Errorf("error accepting connection: %w", err)
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}
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go s.handleTLSClient(c)
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}
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panic("unexpected state")
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}
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func (s *Server) handleTLSClient(c net.Conn) {
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tlsConn, ok := c.(*tls.Conn)
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if !ok {
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gen502Page("unknown", "this should be impossible").Write(c)
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c.Close()
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return
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}
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tlsConn.Handshake()
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sName := tlsConn.ConnectionState().ServerName
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s.clientsLock.RLock()
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set, ok := s.clients[sName]
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s.clientsLock.RUnlock()
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if !ok || len(set) == 0 {
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gen502Page(sName, "no backends connected").Write(c)
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c.Close()
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return
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}
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var (
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sesh *yamux.Session
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stream *yamux.Stream
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count int
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err error
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)
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retry:
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sesh = set[rand.Intn(len(set))]
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stream, err = sesh.OpenStream()
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if err != nil {
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if count > 3 {
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gen502Page(sName, "no working session").Write(c)
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c.Close()
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return
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}
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count++
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goto retry
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}
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go io.Copy(c, stream)
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io.Copy(stream, c)
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2019-11-30 19:08:12 +00:00
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}
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