150 lines
3.4 KiB
Go
150 lines
3.4 KiB
Go
package server
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import (
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"encoding/base64"
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"fmt"
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"log"
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"net"
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"sync"
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"github.com/x-grk/longpolling-remote-access/internal/proto"
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)
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// forwardManager owns the host-side listeners for port-forward rules. It
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// supports three transports:
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// - "http": tunneled over the HTTP long-poll channel (works anywhere nginx
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// reaches, highest latency);
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// - "tcp": direct TCP multiplexed over the 8446 tunnel (low latency);
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// - "udp": direct UDP over the 8446 channel.
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type forwardManager struct {
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hub *Hub
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tun *tunnelHub
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udp *udpRelay
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mu sync.Mutex
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lst map[int64]net.Listener // TCP listeners for http/tcp rules
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}
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func newForwardManager(hub *Hub, tun *tunnelHub, udp *udpRelay) *forwardManager {
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return &forwardManager{hub: hub, tun: tun, udp: udp, lst: map[int64]net.Listener{}}
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}
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// open starts the host-side listener(s) for a rule.
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func (m *forwardManager) open(rule ForwardRule) error {
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m.close(rule.ID)
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switch rule.Proto {
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case "udp":
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if err := m.udp.openRulePort(rule); err != nil {
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return err
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}
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log.Printf("forward[udp]: %s:%d -> agent %s :%d", rule.ListenAddr, rule.HostPort, rule.AgentID, rule.ClientPort)
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return nil
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default: // "http" and "tcp" both listen TCP on the host port
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addr := fmt.Sprintf("%s:%d", rule.ListenAddr, rule.HostPort)
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ln, err := net.Listen("tcp", addr)
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if err != nil {
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return err
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}
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m.mu.Lock()
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m.lst[rule.ID] = ln
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m.mu.Unlock()
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log.Printf("forward[%s]: %s -> agent %s :%d", rule.Proto, addr, rule.AgentID, rule.ClientPort)
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go m.acceptTCP(rule, ln)
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return nil
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}
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}
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func (m *forwardManager) close(ruleID int64) {
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m.mu.Lock()
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ln := m.lst[ruleID]
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delete(m.lst, ruleID)
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m.mu.Unlock()
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if ln != nil {
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_ = ln.Close()
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}
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m.udp.closeRulePort(ruleID)
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}
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func (m *forwardManager) closeAll() {
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m.mu.Lock()
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lst := m.lst
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m.lst = map[int64]net.Listener{}
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m.mu.Unlock()
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for _, ln := range lst {
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_ = ln.Close()
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}
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}
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func (m *forwardManager) acceptTCP(rule ForwardRule, ln net.Listener) {
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for {
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conn, err := ln.Accept()
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if err != nil {
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return
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}
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if tc, ok := conn.(*net.TCPConn); ok {
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_ = tc.SetNoDelay(true)
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}
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if rule.Proto == "tcp" {
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go m.bridgeDirect(rule, conn)
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} else {
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go m.bridgeHTTP(rule, conn)
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}
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}
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}
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// bridgeDirect wires a connection to the agent's low-latency 8446 tunnel.
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func (m *forwardManager) bridgeDirect(rule ForwardRule, conn net.Conn) {
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at := m.tun.get(rule.AgentID)
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if at == nil {
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// No direct tunnel (agent offline or 8446 unreachable).
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conn.Close()
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return
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}
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at.openStream(rule.ClientPort, conn)
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}
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// bridgeHTTP wires a connection through the HTTP long-poll hub session.
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func (m *forwardManager) bridgeHTTP(rule ForwardRule, conn net.Conn) {
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sess := m.hub.CreateForward(rule.AgentID, rule.ClientPort)
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defer m.hub.CloseSession(sess.ID)
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defer conn.Close()
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go func() {
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defer m.hub.CloseSession(sess.ID)
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buf := make([]byte, 32*1024)
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for {
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n, err := conn.Read(buf)
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if n > 0 {
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sess.PushIn(proto.InFrame{
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Type: proto.FrameStdin,
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Data: base64.StdEncoding.EncodeToString(buf[:n]),
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})
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}
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if err != nil {
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sess.PushIn(proto.InFrame{Type: proto.FrameClose})
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return
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}
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}
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}()
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for {
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select {
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case <-sess.Done():
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return
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case out, ok := <-sess.Out():
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if !ok || out.Exit {
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return
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}
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if out.Data != "" {
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b, err := base64.StdEncoding.DecodeString(out.Data)
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if err != nil {
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return
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}
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if _, err := conn.Write(b); err != nil {
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return
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}
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}
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}
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}
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}
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