Xbase++

Get Received SSH Bytes into a BinData

Demonstrates the Chilkat Ssh.GetReceivedBd method, which appends the bytes currently in a channel's normal receive buffer to a BinData. The first argument is the channel number and the second is the BinData. The channel receive buffer is cleared afterward; existing bytes in the BinData are preserved.

Background: When the remote command emits binary — a tarball, an image, a compressed stream — decoding it as text through a charset would corrupt it. BinData keeps the bytes exactly as received, so you can write them to a file, hash them, or hand them to another API. Like the StringBuilder form it appends, making it easy to accumulate across successive reads. On failure the BinData is left unchanged.

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LOCAL nSuccess
LOCAL oSsh
LOCAL nSshPort
LOCAL cPassword
LOCAL nChannelNum
LOCAL oBd

nSuccess := 0

//  Demonstrates the Ssh.GetReceivedBd method, which appends the bytes currently in a channel's
//  receive buffer to a BinData.  The 1st argument is the channel number and the 2nd is the
//  BinData.  The channel receive buffer is cleared afterward.

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

//  Run a command whose output may be binary.
nSuccess := oSsh:SendReqExec(nChannelNum, "cat /usr/bin/hostname")
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

//  Append the raw received bytes to a BinData.  Existing bytes in the BinData are preserved.
oBd := CreateObject("Chilkat.BinData")
nSuccess := oSsh:GetReceivedBd(nChannelNum, oBd)
IF (nSuccess == 0)
    ? oSsh:LastErrorText
    oSsh:destroy()
    oBd:destroy()
    RETURN
ENDIF

? "Bytes received: " + Str(oBd:NumBytes)

oSsh:Disconnect()

oSsh:destroy()
oBd:destroy()