PowerBuilder

Get the Number of Bytes Buffered on an SSH Channel

Demonstrates the Chilkat Ssh.GetReceivedNumBytes method, which returns how many bytes are currently available in a channel's normal receive buffer. The only argument is the channel number. It returns -1 when the channel number is invalid or its retained resources have been released.

Background: This is a non-consuming look at how much is waiting, useful for deciding whether to retrieve now or keep reading, and for reporting progress on a large transfer. It counts only the normal receive buffer — bytes in the separate stderr buffer are excluded when StderrToStdout is false. Note that data received earlier can remain available even after a disconnect, so a positive count does not imply the connection is still up.

Chilkat PowerBuilder Downloads

Download Chilkat for PowerBuilder

PowerBuilder

integer li_rc
integer li_Success
oleobject loo_Ssh
integer li_SshPort
string ls_Password
integer li_ChannelNum
integer li_NumBytes
string ls_Output

li_Success = 0

//  Demonstrates the Ssh.GetReceivedNumBytes method, which returns the number of bytes currently
//  available in a channel's normal receive buffer.  The only argument is the channel number.
//  It returns -1 for an invalid channel or one whose resources have been released.

loo_Ssh = create oleobject
li_rc = loo_Ssh.ConnectToNewObject("Chilkat.Ssh")
if li_rc < 0 then
    destroy loo_Ssh
    MessageBox("Error","Connecting to COM object failed")
    return
end if

li_SshPort = 22
li_Success = loo_Ssh.Connect("ssh.example.com",li_SshPort)
if li_Success = 0 then
    Write-Debug loo_Ssh.LastErrorText
    destroy loo_Ssh
    return
end if

//  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.
ls_Password = "mySshPassword"

li_Success = loo_Ssh.AuthenticatePw("mySshLogin",ls_Password)
if li_Success = 0 then
    Write-Debug loo_Ssh.LastErrorText
    destroy loo_Ssh
    return
end if

li_ChannelNum = loo_Ssh.OpenSessionChannel()
if li_ChannelNum < 0 then
    Write-Debug loo_Ssh.LastErrorText
    destroy loo_Ssh
    return
end if

li_Success = loo_Ssh.SendReqExec(li_ChannelNum,"ls -l /tmp")
if li_Success = 0 then
    Write-Debug loo_Ssh.LastErrorText
    destroy loo_Ssh
    return
end if

//  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.
loo_Ssh.ReadTimeoutMs = 15000

li_Success = loo_Ssh.ChannelReceiveToClose(li_ChannelNum)
if li_Success = 0 then
    Write-Debug loo_Ssh.LastErrorText
    destroy loo_Ssh
    return
end if

//  Find out how much is waiting before retrieving it.
li_NumBytes = loo_Ssh.GetReceivedNumBytes(li_ChannelNum)
if li_NumBytes < 0 then
    Write-Debug "Invalid channel, or its resources were already released."
    destroy loo_Ssh
    return
end if

Write-Debug "Bytes available: " + string(li_NumBytes)

ls_Output = loo_Ssh.GetReceivedText(li_ChannelNum,"utf-8")
if loo_Ssh.LastMethodSuccess = 0 then
    Write-Debug loo_Ssh.LastErrorText
    destroy loo_Ssh
    return
end if

Write-Debug ls_Output

loo_Ssh.Disconnect()


destroy loo_Ssh