Thread: interfacing with a program

Hi

My question is, how can a program manipulate some other program, for starters I'm thinking something really basic, just accessing a console program( where as it stands and waits for a gets() input) so I could then "manage" it from my program. I am wondering around API functions to do this, looking into what can be done with window handles, but can't find anything to grasp on, so if there is any knowledge on the subject, a link or anything.

Thanks very much

hmmm, thats what I thought the SendMessage between progs, I just made a small little brute force prog. just for sports and another very simple as I said program that waits for a gets input, so I'm trying to access the gets program from the brute_force prog., and as you said and as I thought the SendMessage function comes into play, I'll try it now, be back with feedback

and thank you

back so quick, I looked at the SendMessage and the first param HWND is pretty simple a handle which I got, then the UINT msg, now it is obvious that it takes a unsig. int as one of the predifined macros, now an onward question so I don't coplicate it all too much, how can I send some text to another program, cuz I can't quite visualize it with the basic SendMessage or are there any secrets in the WPARAM and LPARAM?

I don't think this would work cuz the simple (gets) prog. has no GetMessage funct. so I don't see a way for him to handle the messages, please correct me if I'm wrong. (and with that being said, like a gazillion questions arose in my head)

it's C

Originally Posted by Crazed

back so quick, I looked at the SendMessage and the first param HWND is pretty simple a handle which I got, then the UINT msg, now it is obvious that it takes a unsig. int as one of the predifined macros, now an onward question so I don't coplicate it all too much, how can I send some text to another program, cuz I can't quite visualize it with the basic SendMessage or are there any secrets in the WPARAM and LPARAM?

How about using InterProcess Communications (IPC)? An example follows. Start the server first.

Code:

//Common.h
#pragma comment( lib, "user32.lib" )   
#include <stdio.h>
#include <windows.h>

#ifndef __MYIPC__
#define __MYIPC__

#define MAX_MESSAGE_SIZE     0x10000
#define HEADER_SIZE (2 * sizeof(DWORD) + sizeof(HWND))
#define SERVERWNDCLASSNAME      "MYSERVERWND001"
#define WINSERVERNAME       "MYSERVER001"
#define SETSTRINGLEN(szInputString,iIndex)    ((szInputString)[(iIndex)]='\0')
#define WM_SEND_DATA           		WM_APP 
#define WM_SHUTDOWN_SERVER          WM_APP + 1

typedef struct _MYDATASTRUCTURE
{
    DWORD cbSize;
    DWORD iMessage;
    HWND hClient;
    CHAR Data[MAX_MESSAGE_SIZE - HEADER_SIZE];  
}MYDATASTRUCTURE,*LP_MYDATASTRUCTURE;

#endif __MYIPC__

Code:

//Client.cpp
#include "common.h"

HWND hServer;
DWORD pID;

BOOL WINAPI TransferData(DWORD dwMessage, const char *pBuffer, DWORD dwBytes) 
{
    BOOL bSend;
    COPYDATASTRUCT cpStructData;
    LP_MYDATASTRUCTURE lpMsg;
    cpStructData.cbData = dwBytes + HEADER_SIZE;
    lpMsg = (LP_MYDATASTRUCTURE)LocalAlloc(LPTR,cpStructData.cbData);
    lpMsg->hClient = NULL;
    lpMsg->iMessage = dwMessage;
    lpMsg->cbSize = dwBytes;
    cpStructData.lpData = lpMsg;
    if(pBuffer!=NULL)
    {
        SETSTRINGLEN(lpMsg->Data,dwBytes);
        memcpy((void *) lpMsg->Data,(const void*)pBuffer,dwBytes);
    }
    bSend = SendMessage(hServer,WM_COPYDATA, (WPARAM)hServer,(LPARAM)&cpStructData);
    return(bSend);
}  

int main(void)
{
    CHAR szWndName[256] = {0};    
    CHAR szData[256] = {0};

    pID = GetCurrentProcessId();
    sprintf(szWndName,"PROCESSID %.X",pID);
    SetConsoleTitle(szWndName);
    if((hServer = FindWindow((LPCTSTR)SERVERWNDCLASSNAME,NULL)) == NULL)
        printf("Please start the server!\n");
    else
    {
        strcpy(szData, "Testing, testing one, two three!!");
        TransferData(WM_SEND_DATA  ,szData, strlen(szData));
        Sleep(5000);
        strcpy(szData, "Let's shutdown the server.");
        TransferData(WM_SHUTDOWN_SERVER ,szData,strlen(szData));

    }
    return 0;
}

Code:

//Server.cpp
#pragma warning( disable : 4715 )
#include "common.h"

LRESULT CALLBACK WMIPCWNDPROC(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
    LP_MYDATASTRUCTURE lpMessage;

    if(uMsg == WM_COPYDATA)
    {
        lpMessage = (LP_MYDATASTRUCTURE)((COPYDATASTRUCT*)lParam)->lpData;
        SETSTRINGLEN(lpMessage->Data,(lpMessage->cbSize));
        switch(lpMessage->iMessage)
        {
            case    WM_SEND_DATA:
                printf("\nOK, we got a message from the other program, Let's print it\n");
                printf(lpMessage->Data);                
                break;
            case   WM_SHUTDOWN_SERVER:
                printf("\nWell, the other program wants us to shutdown. Let's print the message and shut down\n");
                printf(lpMessage->Data); 
                PostQuitMessage(0);
                break;
        }
    }     
    else
        return DefWindowProc(hwnd, uMsg, wParam, lParam);
}

int main(void)
{
    MSG iMessage;
    BOOL bVal;
    WNDCLASS WMClass;

    SetConsoleTitle(WINSERVERNAME);
    WMClass.hInstance = GetModuleHandle(NULL);
    WMClass.lpszClassName = SERVERWNDCLASSNAME;
    WMClass.cbClsExtra = 0;
    WMClass.cbWndExtra = 0;
    WMClass.hbrBackground = NULL;
    WMClass.hCursor = NULL;
    WMClass.hIcon = NULL;
    WMClass.lpszMenuName = NULL;
    WMClass.style = CS_GLOBALCLASS;
    WMClass.lpfnWndProc = WMIPCWNDPROC;
    if(RegisterClass(&WMClass) == 0)
        printf("Class registration failed!\n");
    else
    {
        if(CreateWindow((LPCTSTR)SERVERWNDCLASSNAME, NULL, 0, 0, 0, 0, 0,
            NULL, NULL, WMClass.hInstance, NULL) == NULL)
        {
            printf("Can't create server window\n");
        }
        else
        {
            printf("Server successfully started\n");
            while((bVal = GetMessage(&iMessage, NULL, 0, 0)) && (bVal != -1))
                DispatchMessage(&iMessage);
        }               
    } 
    return 0;
}

Originally Posted by iMalc

WM_COPYDATA is what you want - google it!

The IPC example I posted does use the WM_COPYDATA method.