access violation while using Lnet TCP Server Console
lazarus / 38-Networking and Web Programming

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opendelphi · 2019-04-18 11:43

Hi guys , i am trying to extend the lnet tcp server console sample by
allowing receiving files from tcp server .
the error msg while try to download the file from server
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i An
unhandled exception occurred at $0000000000428D7F:                   
                                EAccessViolation: Access violation   
    $0000000000428D7F                            $000000000047840F
line 1086 of ../lib/lnet.pp                                          
                               $0000000000400EC5 line 167 of
lserver.pp  so this is server side code on receive
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i    if
aSocket.GetMessage(FServerReceivedStr) > 0 then begin    if
FServerReceivedStr <> 'file' then     writeln(FServerReceivedStr)   
 else        begin         
FIStream.LoadFromFile('/root/Desktop/enumeration/server/file.txt');  
      n := FIStream.Size;          SetLength(FBuffer, FIStream.Size); 
        n := Length(FBuffer);          FIStream.Position := 0;       
 FIStream.Read(FBuffer[0], FIStream.Size);          n :=
Length(FBuffer);          FPos := 0;    // send image         
OnCa(aSocket);        end;     // if send fails write error   //
end; end;end;                         
on Can Send :

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i  if
FServerReceivedStr = 'file' then  begin  { repeat the sending until we
sent the whole buffer, or .Send return 0 -- means we filled the send
buffer for now. NOTE: FSendIndex  has to begin at 1 for a string! }  
repeat    { try to send the rest of the buffer we didn't send yet }  
  n := Length(FBuffer) - FPos;      if n > 0 then        n :=
FCon.Send(FBuffer[FPos], n);    { if we sent something, move us in the
buffer so we don't re-send the same part }      Inc(FPos, n);    until
(n = 0) or (FPos > Length(FBuffer));  end  else   
FCon.SendMessage(FServerReceivedStr, aSocket);

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lucamar · 2019-04-18 14:14

I have a limited knowledge of lnet but there doesn't seem to be
anything very wrong in those snippets, other than the total lack of
exception handling in both, and the multiple times you set n (without
using it for anything) to the same value in one form or another in the
first.

Can you share a compilable demo or more detailed code (p.e. to see
where and how you're creating the streams, what OnCa() does etc.)? And
what's there in the lines pointed to by the exception message?

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opendelphi · 2019-04-18 15:20

i have fixed that error but still not able to get the file from server
into client , below is example of code .