PureBasic

Send CLOSE on an SSH Channel

Demonstrates the Chilkat Ssh.ChannelSendClose method, which sends an SSH CLOSE message for a channel and immediately marks it locally closed. The only argument is the channel number. It does not wait for remote EOF, remote CLOSE, or an exit status.

Background: CLOSE shuts down both directions of the channel, unlike EOF which closes only your side. Because the call returns without waiting for the remote side to acknowledge, it does not guarantee the remote process has terminated — so retrieve any output and exit status you care about before calling it. Afterward ChannelIsOpen reports false, though NumOpenChannels may still count the channel until final remote-close processing.

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PureBasic

IncludeFile "CkSsh.pb"

Procedure ChilkatExample()

    success.i = 0

    ;  Demonstrates the Ssh.ChannelSendClose method, which sends an SSH CLOSE message for a channel
    ;  and immediately marks it locally closed.  The only argument is the channel number.  It does
    ;  not wait for remote EOF, remote CLOSE, or an exit status.

    ssh.i = CkSsh::ckCreate()
    If ssh.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    sshPort.i = 22
    success = CkSsh::ckConnect(ssh,"ssh.example.com",sshPort)
    If success = 0
        Debug CkSsh::ckLastErrorText(ssh)
        CkSsh::ckDispose(ssh)
        ProcedureReturn
    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.
    password.s = "mySshPassword"

    success = CkSsh::ckAuthenticatePw(ssh,"mySshLogin",password)
    If success = 0
        Debug CkSsh::ckLastErrorText(ssh)
        CkSsh::ckDispose(ssh)
        ProcedureReturn
    EndIf

    channelNum.i = CkSsh::ckOpenSessionChannel(ssh)
    If channelNum < 0
        Debug CkSsh::ckLastErrorText(ssh)
        CkSsh::ckDispose(ssh)
        ProcedureReturn
    EndIf

    success = CkSsh::ckSendReqExec(ssh,channelNum,"uptime")
    If success = 0
        Debug CkSsh::ckLastErrorText(ssh)
        CkSsh::ckDispose(ssh)
        ProcedureReturn
    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.
    CkSsh::setCkReadTimeoutMs(ssh, 15000)

    success = CkSsh::ckChannelReceiveToClose(ssh,channelNum)
    If success = 0
        Debug CkSsh::ckLastErrorText(ssh)
        CkSsh::ckDispose(ssh)
        ProcedureReturn
    EndIf

    output.s = CkSsh::ckGetReceivedText(ssh,channelNum,"utf-8")
    If CkSsh::ckLastMethodSuccess(ssh) = 0
        Debug CkSsh::ckLastErrorText(ssh)
        CkSsh::ckDispose(ssh)
        ProcedureReturn
    EndIf

    Debug output

    ;  Send CLOSE for the channel.
    success = CkSsh::ckChannelSendClose(ssh,channelNum)
    If success = 0
        Debug CkSsh::ckLastErrorText(ssh)
        CkSsh::ckDispose(ssh)
        ProcedureReturn
    EndIf

    ;  After a successful call, the channel is no longer reported as open.
    If CkSsh::ckChannelIsOpen(ssh,channelNum)
        Debug "Still open."
    Else
        Debug "The channel is closed."
    EndIf

    CkSsh::ckDisconnect(ssh)


    CkSsh::ckDispose(ssh)


    ProcedureReturn
EndProcedure