PureBasic

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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PureBasic

IncludeFile "CkSsh.pb"

Procedure ChilkatExample()

    success.i = 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.

    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,"ls -l /tmp")
    If success = 0
        Debug CkSsh::ckLastErrorText(ssh)
        CkSsh::ckDispose(ssh)
        ProcedureReturn
    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.
    pollTimeoutMs.i = 5000
    result.i = CkSsh::ckWaitForChannelMessage(ssh,pollTimeoutMs)

    If result = -2
        Debug CkSsh::ckLastErrorText(ssh)
        CkSsh::ckDispose(ssh)
        ProcedureReturn
    EndIf

    If result = -1
        Debug "No channel message arrived before the timeout."
    EndIf

    If result >= 0
        Debug "Processed a message for channel " + Str(result)
    EndIf

    CkSsh::ckDisconnect(ssh)


    CkSsh::ckDispose(ssh)


    ProcedureReturn
EndProcedure