liigo's bho

A sample IE BHO for getting webbrowser's POST data in BeforeNavigate2 event.

Compiler: VC6

Install: regsvr32 full/path/to/liigobho.dll (need administrator privileges)

Uninstall: regsvr32 full/path/to/liigobho.dll (need administrator privileges)

The core code in file BhoApp.cpp list here:

STDMETHODIMP CBhoApp::Invoke(DISPID dispidMember, REFIID riid, LCID lcid, WORD wFlags, DISPPARAMS *pDispParams, VARIANT *pvarResult, EXCEPINFO *pExcepInfo, UINT *puArgErr)
{
	switch(dispidMember)
	{
	case DISPID_BEFORENAVIGATE2:
		{
			//liigo 2013-6-26:
			//there are 7 args in pDispParams->rgvarg[0] to pDispParams->rgvarg[6]
			assert(pDispParams->cArgs == 7);

			//Arg0: Cancel
			VARIANTARG argCancel = pDispParams->rgvarg[0];
			assert(argCancel.vt == (VT_BYREF|VT_BOOL));
			//we can set VARIANT_TRUE to cancel the navigation
			// *(argCancel.pboolVal) = VARIANT_TRUE;

			//Arg1: Headers
			VARIANTARG argHeaders = pDispParams->rgvarg[1];
			assert(argHeaders.vt == (VT_BYREF|VT_VARIANT));
			assert(argHeaders.pvarVal->vt == VT_BSTR);
			BSTR bstrHeaders = argHeaders.pvarVal->bstrVal;
			MessageBoxW(0, bstrHeaders, L"headers", MB_OK);

			//Arg2: PostData
			VARIANTARG argPostData = pDispParams->rgvarg[2];
			assert(argPostData.vt == (VT_BYREF|VT_VARIANT));
			assert(argPostData.pvarVal->vt == (VT_BYREF|VT_VARIANT));
			if(argPostData.pvarVal->pvarVal->vt != VT_EMPTY)
			{
				assert(argPostData.pvarVal->pvarVal->vt == (VT_ARRAY|VT_UI1));
				SAFEARRAY* pSafeArray = argPostData.pvarVal->pvarVal->parray;
				assert(pSafeArray);
				assert(pSafeArray->cDims == 1 && pSafeArray->cbElements == 1); //array of VT_UI1
				unsigned int nPostDataSize = pSafeArray->rgsabound[0].cElements * pSafeArray->cbElements; //in bytes
				void* pPostData = pSafeArray->pvData;
				ShowDataMessage(pPostData, nPostDataSize, "post data binary");
				MessageBoxA(0, (char*)pPostData, "post data string", MB_OK);
			}

			//Arg3: TargetFrameName
			VARIANTARG argTargetFrameName = pDispParams->rgvarg[3];
			assert(argTargetFrameName.vt == (VT_BYREF|VT_VARIANT));
			assert(argTargetFrameName.pvarVal->vt == VT_BSTR);
			BSTR bstrTargetFrameName = argTargetFrameName.pvarVal->bstrVal;
			MessageBoxW(0, bstrTargetFrameName, L"TargetFrameName", MB_OK);

			//Arg4: Flags
			VARIANTARG argFlags = pDispParams->rgvarg[4];
			assert(argFlags.vt == (VT_BYREF|VT_VARIANT));
			assert(argFlags.pvarVal->vt == VT_I4);
			LONG lFlags = argFlags.pvarVal->lVal;

			//Arg5: Url
			VARIANTARG argUrl = pDispParams->rgvarg[5];
			assert(argUrl.vt == (VT_BYREF|VT_VARIANT));
			assert(argUrl.pvarVal->vt == VT_BSTR);
			BSTR bstrUrl = argUrl.pvarVal->bstrVal;
			MessageBoxW(0, bstrUrl, L"URL", MB_OK);

			//Arg6: WebBrowser
			VARIANTARG argWebBrowser = pDispParams->rgvarg[6];
			assert(argWebBrowser.vt == VT_DISPATCH);
			IDispatch* pDispWebBrowser = argWebBrowser.pdispVal;

			return S_OK;
		}