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add timeout for keepalive reply #442

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ximiximi1 wants to merge 2 commits into from
+45 −18
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add timeout for keepalive reply #442

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e06c63b
add timeout for keepalive reply
ximiximi1 Aug 20, 2023
6214761
Merge branch 'jpillora:master' into sshkeepalive-patch
ximiximi1 Mar 21, 2024
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63 changes: 45 additions & 18 deletions share/tunnel/tunnel.go
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Original file line number Diff line number Diff line change
Expand Up @@ -18,7 +18,7 @@ import (
"golang.org/x/sync/errgroup"
)

//Config a Tunnel
// Config a Tunnel
type Config struct {
*cio.Logger
Inbound bool
Expand All @@ -27,13 +27,13 @@ type Config struct {
KeepAlive time.Duration
}

//Tunnel represents an SSH tunnel with proxy capabilities.
//Both chisel client and server are Tunnels.
//chisel client has a single set of remotes, whereas
//chisel server has multiple sets of remotes (one set per client).
//Each remote has a 1:1 mapping to a proxy.
//Proxies listen, send data over ssh, and the other end of the ssh connection
//communicates with the endpoint and returns the response.
// Tunnel represents an SSH tunnel with proxy capabilities.
// Both chisel client and server are Tunnels.
// chisel client has a single set of remotes, whereas
// chisel server has multiple sets of remotes (one set per client).
// Each remote has a 1:1 mapping to a proxy.
// Proxies listen, send data over ssh, and the other end of the ssh connection
// communicates with the endpoint and returns the response.
type Tunnel struct {
Config
//ssh connection
Expand All @@ -47,7 +47,7 @@ type Tunnel struct {
socksServer *socks5.Server
}

//New Tunnel from the given Config
// New Tunnel from the given Config
func New(c Config) *Tunnel {
c.Logger = c.Logger.Fork("tun")
t := &Tunnel{
Expand All @@ -68,7 +68,7 @@ func New(c Config) *Tunnel {
return t
}

//BindSSH provides an active SSH for use for tunnelling
// BindSSH provides an active SSH for use for tunnelling
func (t *Tunnel) BindSSH(ctx context.Context, c ssh.Conn, reqs <-chan *ssh.Request, chans <-chan ssh.NewChannel) error {
//link ctx to ssh-conn
go func() {
Expand Down Expand Up @@ -104,7 +104,7 @@ func (t *Tunnel) BindSSH(ctx context.Context, c ssh.Conn, reqs <-chan *ssh.Reque
return err
}

//getSSH blocks while connecting
// getSSH blocks while connecting
func (t *Tunnel) getSSH(ctx context.Context) ssh.Conn {
//cancelled already?
if isDone(ctx) {
Expand Down Expand Up @@ -140,8 +140,8 @@ func (t *Tunnel) activatingConnWait() <-chan struct{} {
return ch
}

//BindRemotes converts the given remotes into proxies, and blocks
//until the caller cancels the context or there is a proxy error.
// BindRemotes converts the given remotes into proxies, and blocks
// until the caller cancels the context or there is a proxy error.
func (t *Tunnel) BindRemotes(ctx context.Context, remotes []*settings.Remote) error {
if len(remotes) == 0 {
return errors.New("no remotes")
Expand Down Expand Up @@ -174,16 +174,43 @@ func (t *Tunnel) BindRemotes(ctx context.Context, remotes []*settings.Remote) er

func (t *Tunnel) keepAliveLoop(sshConn ssh.Conn) {
//ping forever

//reply_timeout set to KeepAlive interval, if KeepAlive is less than 10s, set reply_timeout to 10s
//maybe a new config option for reply_timeout is also fine
reply_timeout := t.Config.KeepAlive

if reply_timeout < 10 * time.Second {
reply_timeout = 10 * time.Second
}

for {
time.Sleep(t.Config.KeepAlive)
_, b, err := sshConn.SendRequest("ping", true, nil)

errChannel := make(chan error, 2)

time.AfterFunc(reply_timeout, func() {
errChannel <- errors.New("KEEPALIVE REPLY TIMEOUT ERROR")
})

go func() {
_, b, err := sshConn.SendRequest("ping", true, nil)

ret_err := err

if err == nil && len(b) > 0 && !bytes.Equal(b, []byte("pong")) {
t.Debugf("strange ping response")
ret_err = errors.New("strange ping response")
}

errChannel <- ret_err
}()

err := <-errChannel

if err != nil {
break
}
if len(b) > 0 && !bytes.Equal(b, []byte("pong")) {
t.Debugf("strange ping response")
break
}

}
//close ssh connection on abnormal ping
sshConn.Close()
Expand Down