Xbase++

Wait for a Message on Any SSH Channel

Demonstrates the Chilkat Ssh.WaitForChannelMessage method, which waits for the next SSH channel message on any channel. The only argument is the poll timeout: 0 for a nonblocking check, a positive value to wait that long, or a negative value to wait with no method-level timeout. It returns the channel number the message belongs to, -1 if nothing arrived before the timeout, or -2 on another error such as a lost connection.

Background: When several channels are active at once, waiting on one specific channel would block while others sit ready. This method is the multiplexed alternative — it returns as soon as any channel has activity and tells you which one, so a single loop can service them all. The explicit timeout argument governs the wait; shorter ReadTimeoutMs values do not cut it short.

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LOCAL nSuccess
LOCAL oSsh
LOCAL nSshPort
LOCAL cPassword
LOCAL nChannelNum
LOCAL nPollTimeoutMs
LOCAL nResult

nSuccess := 0

//  Demonstrates the Ssh.WaitForChannelMessage method, which waits for the next SSH channel
//  message on ANY channel.  The only argument is the poll timeout in milliseconds: 0 for a
//  nonblocking check, a positive value to wait that long, or a negative value to wait with no
//  method-level timeout.

oSsh := CreateObject("Chilkat.Ssh")

nSshPort := 22
nSuccess := oSsh:Connect("ssh.example.com", nSshPort)
IF (nSuccess == 0)
    ? oSsh:LastErrorText
    oSsh:destroy()
    RETURN
ENDIF

//  Normally you would not hard-code the password in source.  You should instead obtain it
//  from an interactive prompt, environment variable, or a secrets vault.
cPassword := "mySshPassword"

nSuccess := oSsh:AuthenticatePw("mySshLogin", cPassword)
IF (nSuccess == 0)
    ? oSsh:LastErrorText
    oSsh:destroy()
    RETURN
ENDIF

nChannelNum := oSsh:OpenSessionChannel()
IF (nChannelNum < 0)
    ? oSsh:LastErrorText
    oSsh:destroy()
    RETURN
ENDIF

nSuccess := oSsh:SendReqExec(nChannelNum, "ls -l /tmp")
IF (nSuccess == 0)
    ? oSsh:LastErrorText
    oSsh:destroy()
    RETURN
ENDIF

//  Wait up to 5 seconds for the next channel message.  The return value is the channel number
//  the message belongs to, -1 if nothing arrived before the timeout, or -2 on another error.
nPollTimeoutMs := 5000
nResult := oSsh:WaitForChannelMessage(nPollTimeoutMs)

IF (nResult == -2)
    ? oSsh:LastErrorText
    oSsh:destroy()
    RETURN
ENDIF

IF (nResult == -1)
    ? "No channel message arrived before the timeout."
ENDIF

IF (nResult >= 0)
    ? "Processed a message for channel " + Str(nResult)
ENDIF

oSsh:Disconnect()

oSsh:destroy()