Xbase++

Check Whether SSH Channel CLOSE Was Received

Demonstrates the Chilkat Ssh.ChannelReceivedClose method, which reports whether an SSH CLOSE message has been received for a channel. The only argument is the channel number. Remote CLOSE is distinct from EOF and closes the channel in both directions.

Background: Remote CLOSE is the definitive end of a channel's life. Once it is processed, ChannelIsOpen becomes false and the channel is normally removed from NumOpenChannels. Checking it distinguishes "the server finished sending output" (EOF) from "the channel is fully finished" (CLOSE) — which is what you want before concluding a remote command has completely wrapped up.

Chilkat Xbase++ Downloads

Download Chilkat for Xbase++

Xbase++

LOCAL nSuccess
LOCAL oSsh
LOCAL nSshPort
LOCAL cPassword
LOCAL nChannelNum

nSuccess := 0

//  Demonstrates the Ssh.ChannelReceivedClose method, which reports whether an SSH CLOSE message
//  has been received for a channel.  The only argument is the channel number.  Remote CLOSE is
//  distinct from EOF and closes the channel in both directions.

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

//  IMPORTANT: Set a read timeout.  ReadTimeoutMs defaults to 0, which means no limit -- without
//  it, this call waits forever if the server never sends channel close.
oSsh:ReadTimeoutMs := 15000

nSuccess := oSsh:ChannelReceiveToClose(nChannelNum)
IF (nSuccess == 0)
    ? oSsh:LastErrorText
    oSsh:destroy()
    RETURN
ENDIF

//  The server may send EOF before CLOSE.  During that interval EOF is 1 while CLOSE is
//  still 0.
IF (oSsh:ChannelReceivedEof(nChannelNum))
    ? "EOF received."
ENDIF

IF (oSsh:ChannelReceivedClose(nChannelNum))
    ? "Remote CLOSE received -- the channel is closed in both directions."
ELSE
    ? "No remote CLOSE received."
ENDIF

oSsh:Disconnect()

oSsh:destroy()