IntelliLink - An Alternative Windows Version to Online Link Managers

Ștefan-Mihai MOGA

4.96/5 (17 votes)

Nov 8, 2014

GPL3

6 min read

70683

276

A look at the URLDownloadToFile function and architecture of IntelliLink

Introduction

Have you ever owned a website? Did you do some sysadmin work for somebody else? Have you made link exchange? If so, you probably wish to monitor the internal/external links from/to your site.

Background

The easiest way to check the contents of a web page is to download it locally (to a file) and search through it. To accomplish this, we use URLDownloadToFile function, which has the following syntax:

HRESULT URLDownloadToFile(
	LPUNKNOWN pCaller,
	LPCTSTR szURL,
	LPCTSTR szFileName,
	_Reserved_  DWORD dwReserved,
	LPBINDSTATUSCALLBACK lpfnCB);

Parameters

pCaller: A pointer to the controlling IUnknown interface of the calling ActiveX component, if the caller is an ActiveX component. If the calling application is not an ActiveX component, this value can be set to NULL. Otherwise, the caller is a COM object that is contained in another component, such as an ActiveX control in the context of an HTML page. This parameter represents the outermost IUnknown of the calling component. The function attempts the download in the context of the ActiveX client framework, and allows the caller container to receive callbacks on the progress of the download.
szURL: A pointer to a string value that contains the URL to download. Cannot be set to NULL. If the URL is invalid, INET_E_DOWNLOAD_FAILURE is returned.
szFileName: A pointer to a string value containing the name or full path of the file to create for the download. If szFileName includes a path, the target directory must already exist.
dwReserved: Reserved. Must be set to 0.
lpfnCB: A pointer to the IBindStatusCallback interface of the caller. By using IBindStatusCallback::OnProgress, a caller can receive download status. URLDownloadToFile calls the IBindStatusCallback::OnProgress and IBindStatusCallback::OnDataAvailable methods as data is received. The download operation can be cancelled by returning E_ABORT from any callback. This parameter can be set to NULL if status is not required.

Return Value

This function can return one of these values:

S_OK: The download started successfully.
E_OUTOFMEMORY: The buffer length is invalid, or there is insufficient memory to complete the operation.
INET_E_DOWNLOAD_FAILURE: The specified resource or callback interface was invalid.

So, our implementation using the above function will be:

BOOL ProcessHTML(CString strFileName, CString strSourceURL, 
                 CString strTargetURL, CString strURLName)
{
   CString strURL;
   CString strFileLine;
   CString strLineMark;
   BOOL bRetVal = FALSE;

   try
   {
      CStdioFile pInputFile(strFileName, CFile::modeRead | CFile::typeText);
      while (pInputFile.ReadString(strFileLine))
      {
         int nIndex = strFileLine.Find(_T("href="), 0);
         while (nIndex >= 0)
         {
            const int nFirst = strFileLine.Find(_T('\"'), nIndex);
            if (nFirst >= 0)
            {
               const int nLast = strFileLine.Find(_T('\"'), nFirst + 1);
               if (nLast >= 0)
               {
                  strURL = strFileLine.Mid(nFirst + 1, nLast - nFirst - 1);
                  if (strURL.CompareNoCase(strTargetURL) == 0)
                  {
                     TRACE(_T("URL found - %s\n"), strTargetURL);
                     strLineMark.Format(_T(">%s<"), strURLName);
                     if (strFileLine.Find(strLineMark, nLast + 1) >= 0)
                     {
                        TRACE(_T("Name found - %s\n"), strURLName);
                        bRetVal = TRUE;
                     }
                  }
               }
            }
            nIndex = (nFirst == -1) ? -1 : strFileLine.Find(_T("href="), nFirst + 1);
         }
      }
      pInputFile.Close();
   }
   catch (CFileException* pFileException)
   {
      TCHAR lpszError[MAX_STR_LENGTH] = { 0 };
      pFileException->GetErrorMessage(lpszError, MAX_STR_LENGTH);
      pFileException->Delete();
      OutputDebugString(lpszError);
      bRetVal = FALSE;
   }
   VERIFY(DeleteFile(strFileName));
   return bRetVal;
}

BOOL CLinkData::IsValidLink()
{
   BOOL bRetVal = TRUE;
   TCHAR lpszTempPath[MAX_STR_LENGTH] = { 0 };
   TCHAR lpszTempFile[MAX_STR_LENGTH] = { 0 };

   const DWORD dwTempPath = GetTempPath(MAX_STR_LENGTH, lpszTempPath);
   lpszTempPath[dwTempPath] = '\0';
   if (GetTempFileName(lpszTempPath, _T("html"), 0, lpszTempFile) != 0)
   {
      TRACE(_T("URLDownloadToFile(%s)...\n"), GetSourceURL());
      if (URLDownloadToFile(NULL, GetSourceURL(), lpszTempFile, 0, NULL) == S_OK)
      {
         if (!ProcessHTML(lpszTempFile, GetSourceURL(), GetTargetURL(), GetURLName()))
         {
            TRACE(_T("ProcessHTML(%s) has failed\n"), lpszTempFile);
            bRetVal = FALSE;
         }
      }
      else
      {
         TRACE(_T("URLDownloadToFile has failed\n"));
         bRetVal = FALSE;
      }
   }
   else
   {
      TRACE(_T("GetTempFileName has failed\n"));
      bRetVal = FALSE;
   }
   return bRetVal;
}

The Architecture

What do Source URL, Target URL, and URL Name mean in the above piece of code?

Source URL = what web page to check
Target URL = what link should be on the above web page
URL Name = what name should be for the above link

Each URL definition is contained in a CLinkData class, with the following interface:

DWORD GetLinkID(); - Gets ID of the current URL definition
void SetLinkID(DWORD dwLinkID); - Sets ID for the current URL definition
CString GetSourceURL(); - Gets Source URL for current URL definition
void SetSourceURL(CString strSourceURL); - Sets Source URL for current URL definition
CString GetTargetURL(); - Gets Target URL for current URL definition
void SetTargetURL(CString strTargetURL); - Sets Target URL for current URL definition
CString GetURLName(); - Gets URL Name for current URL definition
void SetURLName(CString strURLName); - Sets URL Name for current URL definition
int GetPageRank(); currently not implemented
void SetPageRank(int nPageRank); currently not implemented
BOOL GetStatus(); - Gets status for current URL definition
void SetStatus(BOOL bStatus); - Sets status for current URL definition

Then, we define CLinkList as typedef CArray<CLinkData*> CLinkList;.

This list is managed inside the CLinkSnapshot class, with the following interface:

BOOL RemoveAll(); - Removes all URL definitions from list
int GetSize(); - Gets the size of URL definition list
CLinkData* GetAt(int nIndex); - Gets an URL definition from list
BOOL Refresh(); - Updates the status for each URL definition from list
CLinkData* SelectLink(DWORD dwLinkID); - Searches for a URL definition by its ID
DWORD InsertLink(CString strSourceURL, CString strTargetURL, CString strURLName, int nPageRank, BOOL bStatus); - Inserts a URL definition into list
BOOL DeleteLink(DWORD dwLinkID); - Removes an URL definition from list
BOOL LoadConfig(); - Loads the URL definition list from XML file
BOOL SaveConfig(); - Saves the URL definition list to XML file

The Good, the Bad, and the Ugly

The good thing is that I learned to use Windows ribbons. The bad thing is that I still don't know how to get a web page's PageRank value. The ugly thing is that the processing (i.e., checking link validity) should be done in a separate working thread, but I am planning this change for the next release. Stay tuned!

Final Words

IntelliLink application uses many components that have been published on CodeProject. Many thanks to:

My CMFCListView form view (see source code)
Lee Thomason for his TinyXML2 class
PJ Naughter for his CTrayNotifyIcon class
PJ Naughter for his CVersionInfo class

Further plans: I would like to add support for Google's PageRank as soon as possible.

History

Version 1.04 (November 9^th, 2014): Initial release
Moved source code from CodeProject to GitLab (April 10^th, 2020)
Moved source code from GitLab to GitHub (February 23^rd, 2022)
Version 1.05 (April 28^th, 2022): Added setup project
Version 1.06 (May 23^rd, 2022): Added program to Startup Apps
Version 1.07 (August 20^th, 2022): Updated font size of About dialog
Version 1.08 (August 26^th, 2022): Removed program from Startup Apps
Version 1.09 (September 9^th, 2022): Added Contributors hyperlink to AboutBox dialog
Version 1.10 (January 23^rd, 2023): Updated PJ Naughter's CVersionInfo library to the latest version available
Updated the code to use C++ uniform initialization for all variable declarations
Version 1.11 (January 24^rd, 2023): Updated PJ Naughter's CInstanceChecker library to the latest version available
Updated the code to use C++ uniform initialization for all variable declarations
Replaced NULL throughout the codebase with nullptr
Replaced BOOL throughout the codebase with bool
This means that the minimum requirement for the application is now Microsoft Visual C++ 2010
Version 1.12 (May 27^th, 2023): Updated About dialog with GPLv3 notice
Version 1.13 (June 16^th, 2023): Made persistent the length of columns from interface
Version 1.14 (June 24^th, 2023): Updated PJ Naughter's CTrayNotifyIcon library to the latest version available
Version 1.15 (July 20^th, 2023): Extended application's functionality with two new buttons: Website Review and Webmaster Tools
Version 1.16 (August 20^th, 2023):
- Changed article's download link. Updated the About dialog (email & website)
- Added social media links: Twitter, LinkedIn, Facebook, and Instagram
- Added shortcuts to GitHub repository's Issues, Discussions, and Wiki
Version 1.17 (October 29^th, 2023): Updated PJ Naughter's CTrayNotifyIcon library to the latest version available
Fixed an issue where the CTrayNotifyIcon::OnTrayNotification callback method would not work correctly if the m_NotifyIconData.uTimeout member variable gets updated during runtime of client applications. This can occur when you call CTrayNotifyIcon::SetBalloonDetails. Thanks to Maisala Tuomo for reporting this bug.
Version 1.18 (January 27^th, 2024): Added ReleaseNotes.html and SoftwareContentRegister.html to GitHub repo
Version 1.19 (February 21^st, 2024): Switched MFC application' theme back to native Windows
Version 1.20 (September 6^th, 2024):
- Replaced old XML library from CodeProject with Lee Thomason's TinyXML2 library.
- Implemented User Manual option into Help menu.
- Implemented Check for updates... option into Help menu.