PureBasic

Multiple SendReqExec on the Same Connection

Demonstrates running a series of commands on one SSH connection using SendReqExec. Each exec request requires its own logical channel — this is not a separate SSH connection, just a new session channel on the existing one.

Background: An SSH session channel is single-use for an exec request: once the command runs and the server closes the channel, that channel cannot be reused. Opening a fresh channel per command is cheap, since the expensive work — the TCP connection, key exchange, and authentication — is done once and shared. This is why running ten commands over one connection is far faster than connecting ten times.

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IncludeFile "CkSsh.pb"

Procedure ChilkatExample()

    success.i = 0

    ;  This example requires the Chilkat API to have been previously unlocked.
    ;  See Global Unlock Sample for sample code.

    ;  Demonstrates running a series of commands on one SSH connection using SendReqExec.  Each exec
    ;  request requires its own logical channel.  This is not a new SSH connection -- it is simply a
    ;  new session channel on the existing one.

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

    hostname.s = "ssh.example.com"
    port.i = 22
    success = CkSsh::ckConnect(ssh,hostname,port)
    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

    ;  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)

    ;  ---- 1st command, on its own session channel ----
    channelNum.i = CkSsh::ckOpenSessionChannel(ssh)
    If channelNum < 0
        Debug CkSsh::ckLastErrorText(ssh)
        CkSsh::ckDispose(ssh)
        ProcedureReturn
    EndIf

    success = CkSsh::ckSendReqExec(ssh,channelNum,"ls -al")
    If success = 0
        Debug CkSsh::ckLastErrorText(ssh)
        CkSsh::ckDispose(ssh)
        ProcedureReturn
    EndIf

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

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

    Debug cmdOutput
    Debug "----"

    ;  ---- 2nd command, on a NEW session channel over the same connection ----
    channelNum = CkSsh::ckOpenSessionChannel(ssh)
    If channelNum < 0
        Debug CkSsh::ckLastErrorText(ssh)
        CkSsh::ckDispose(ssh)
        ProcedureReturn
    EndIf

    success = CkSsh::ckSendReqExec(ssh,channelNum,"nslookup chilkatsoft.com")
    If success = 0
        Debug CkSsh::ckLastErrorText(ssh)
        CkSsh::ckDispose(ssh)
        ProcedureReturn
    EndIf

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

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

    Debug cmdOutput

    CkSsh::ckDisconnect(ssh)


    CkSsh::ckDispose(ssh)


    ProcedureReturn
EndProcedure