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package handlers
import (
"dtail/logger"
"dtail/server/user"
"fmt"
"io"
"os"
"strings"
)
// ControlHandler is used for control functions and health monitoring.
type ControlHandler struct {
serverMessages chan string
pong chan struct{}
stop chan struct{}
payload []byte
hostname string
user *user.User
}
// NewControlHandler returns a new control handler.
func NewControlHandler(user *user.User) *ControlHandler {
logger.Debug(user, "Creating control handler")
h := ControlHandler{
serverMessages: make(chan string, 10),
pong: make(chan struct{}, 10),
stop: make(chan struct{}),
user: user,
}
fqdn, err := os.Hostname()
if err != nil {
logger.FatalExit(err)
}
s := strings.Split(fqdn, ".")
h.hostname = s[0]
return &h
}
// Read is to send data to the client via the Reader interface.
func (h *ControlHandler) Read(p []byte) (n int, err error) {
for {
select {
case message := <-h.serverMessages:
wholePayload := []byte(fmt.Sprintf("SERVER|%s|%s\n", h.hostname, message))
n = copy(p, wholePayload)
return
case <-h.pong:
logger.Info(h.user, "Sending pong")
n = copy(p, []byte(".pong\n"))
return
case <-h.stop:
return 0, io.EOF
}
}
}
// Write is to read data to the client via the Writer interface.
func (h *ControlHandler) Write(p []byte) (n int, err error) {
for _, c := range p {
switch c {
case ';':
wholePayload := strings.TrimSpace(string(h.payload))
h.handleCommand(wholePayload)
h.payload = nil
default:
h.payload = append(h.payload, c)
}
}
n = len(p)
return
}
// Close the control handler.
func (h *ControlHandler) Close() {
close(h.stop)
}
// Wait returns the handler stop channel.
func (h *ControlHandler) Wait() <-chan struct{} {
return h.stop
}
func (h *ControlHandler) handleCommand(command string) {
logger.Info(h.user, command)
s := strings.Split(command, " ")
logger.Debug(h.user, "Receiving command", command, s)
switch s[0] {
case "health":
h.serverMessages <- "OK: DTail SSH Server seems fine"
h.serverMessages <- "done;"
case "ping":
h.pong <- struct{}{}
case "debug":
h.serverMessages <- logger.Debug(h.user, "Receiving debug command", command, s)
default:
h.serverMessages <- logger.Warn(h.user, "Received unknown command", command, s)
}
}
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