Sending a HTTP POST request? | Forex Factory

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Sending a HTTP POST request?

  • #1
  • First Post: Jan 6, 2012 5:09pm Jan 6, 2012 5:09pm
To those more informed...

I'm trying to send data from a metatrader terminal up into a website. Sending the data via HTTP GET is impractical given the amount of data that I'm trying to send.

Next alternative is sending the data via HTTP POST and that's where I'm having trouble. Attached is my attempt at sending a proper POST request.

As far as I can tell, the script is able to access the webpage, but fails to pass the necessary POST parameters. Any suggestions on getting this to work?
Attached File(s)
File Type: ex4 HTTP POST 1.ex4   6 KB | 989 downloads
File Type: mq4 HTTP POST 1.mq4   7 KB | 2,743 downloads
  • #2
  • Jan 9, 2012 7:23am Jan 9, 2012 7:23am
Someone has suggested changing the headers, but that doesn't seem to work.

I do know that the HttpSendRequestA function is returning 'false'
  • #3
  • Jan 9, 2012 11:16am Jan 9, 2012 11:16am
I've written some custom "screen scraping" programs to get data from various web sites in the past using libcurl. The hardest ones to implement used POST instead of GET.

On the trickiest ones I ended up using WireShark to sniff the traffic from a browser like Firefox. Then I was able to mimic the the back-and-forth in my own program.

Is this your own web site on someone else's?
You are in a maze of twisty little passages, all alike.
  • #4
  • Jan 9, 2012 2:33pm Jan 9, 2012 2:33pm
It's my site stevegee, so I can change the receiving code as necessary.
  • #5
  • Edited 5:36pm Jan 9, 2012 4:31pm | Edited 5:36pm
Quoting Ronald Raygun
Someone has suggested changing the headers, but that doesn't seem to work.

I do know that the HttpSendRequestA function is returning 'false'
I strongly recommend not to use wininet.dll but instead wget.exe for HTTP purposes. Better documentation, better debugging, more possibilities, no hassle with custom proxy settings etc. Sending a POST request is almost as easy as sending a GET request. Just consider that POST dada is not sent by headers but contained in the request body. So you *may* write your data to a file and specify it as the *body* to use.

My code usually looks like this (there are dependencies to my framework but you are experienced enough to get the idea):

Inserted Code
string response[];
int result = UploadDataFile(filename, response);

/**
 * Upload a file per POST and return the server response
 *
 * @param  string  filename   - filename relativ to "{terminal-directory}experts\files"
 * @param  string  response[] - array containing the server response, if any
 *
 * @return int - error code
 */
int UploadDataFile(string filename, string response[]) {
   // construct shell cmd line 
   string url          = "http://mydomain.com/myurl.php";
   string filesDir     = TerminalPath() +"\\experts\\files";
   string dataFile     = filesDir +"\\"+ filename;
   string responseFile = filesDir +"\\"+ filename +".response";
   string logFile      = filesDir +"\\"+ filename +".log";
   string cmdLine      = "wget.exe \""+ url +"\" --post-file=\""+ dataFile +"\" --header=\"Content-Type: text/plain\" -O \""+ responseFile +"\" -o \""+ logFile +"\"";

   // send POST request 
   if (WinExecAndWait(cmdLine, SW_HIDE) != NO_ERROR)                    // SW_SHOWNORMAL|SW_HIDE
      return(SetLastError(ERR_RUNTIME_ERROR));

   // read server response 
   if (FileReadLines(filename +".response", response, false) == -1)        // FileReadLines() expects a relative path
      return(SetLastError(ERR_RUNTIME_ERROR));

   ...
}
Regards,
Peter
It takes blood, sweat and enough tears to wash away the blood.
  • #6
  • Last Post: Jan 9, 2012 4:46pm Jan 9, 2012 4:46pm
just for completeness my WinExecAndWait() function

Inserted Code
/**
 * Executes an application and waits until finished.
 *
 * @param  string cmdLine - command line
 * @param  int    cmdShow - ShowWindow() command id
 *
 * @return int - error code
 */
int WinExecAndWait(string cmdLine, int cmdShow) {
   string sNull;
   int    iNull[];

   /*STARTUPINFO*/int si[]; InitializeBuffer(si, STARTUPINFO.size);
      si.setCb        (si, 68);
      si.setFlags     (si, STARTF_USESHOWWINDOW);
      si.setShowWindow(si, cmdShow);

   /*PROCESS_INFORMATION*/int pi[]; InitializeBuffer(pi, PROCESS_INFORMATION.size);

   if (!CreateProcessA(sNull, cmdLine, iNull, iNull, false, 0, iNull, sNull, si, pi))
      return(catch("WinExecAndWait(1) ->kernel32.CreateProcessA()   error="+ RtlGetLastWin32Error(), ERR_WIN32_ERROR));

   int result = WaitForSingleObject(pi.hProcess(pi), INFINITE);

   if (result != WAIT_OBJECT_0) {
      if (result == WAIT_FAILED) catch("WinExecAndWait(2) ->kernel32.WaitForSingleObject()   error="+ RtlGetLastWin32Error(), ERR_WIN32_ERROR);
      else                       log("WinExecAndWait() ->kernel32.WaitForSingleObject() => "+ WaitForSingleObjectValueToStr(result));
   }

   CloseHandle(pi.hProcess(pi));
   CloseHandle(pi.hThread(pi));

   return(catch("WinExecAndWait(3)"));
}
It takes blood, sweat and enough tears to wash away the blood.
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