internetdownload.cpp

Visual C++网络通信编程实用案例精逊配套源码 光盘中存放的是书中涉及的所有实例的源代码和经过编译后的应用程序。所有程序均经过测试

#include "stdafx.h"

#include <direct.h>
#include <process.h>
#include <io.h>
#include "InternetDownload.h"


// Filenames to create if a link just uses a directory for a reference -- 
// g_szDefPage is for HTML pages, g_szUnknown is for multimedia files (in which
// case something fatal happened)
const char *g_szDefPage = "index.htm";
const char *g_szUnknown = "unknown.fil";

// The default prefix -- we only support HTTP protocols
static const char *szHttp = "http://";

// Request flags for session initialization:
//	Use existing INET setup, don't redirect to other servers automatically,
//	don't save pages in the browser's cache, always reload a page from the 
//	server (don't use the browser's cached copy)
static DWORD dwHttpRequestFlags =
	   INTERNET_FLAG_EXISTING_CONNECT|
	   INTERNET_FLAG_NO_AUTO_REDIRECT|
       INTERNET_FLAG_DONT_CACHE|
       INTERNET_FLAG_RELOAD; 

// Types of data that we can handle -- we handle it all!
static const TCHAR szHeaders[] = 
		_T("Accept: */* \r");

// Constructor
CInternetDownload::CInternetDownload()
{
	m_hSession = NULL;
	m_nUniqueCount = 0;
}

// Destructor
CInternetDownload::~CInternetDownload()
{
}

// Initialize a new WinInet session
CInternetDownload::RESULTS CInternetDownload::OpenSession(BOOL bUseProxy, CString& strProxyName)
{
	CInternetDownload::RESULTS ret;

	// Open the new session
	m_hSession = ::InternetOpen("SiteSnagger",
					bUseProxy?INTERNET_OPEN_TYPE_PROXY:INTERNET_OPEN_TYPE_PRECONFIG,
					bUseProxy?(LPCTSTR)strProxyName:(LPCTSTR)NULL,
					NULL,0);

	// Did it work??
	if(m_hSession != NULL)
	{
		DWORD dwTimeout = 4000;
		::InternetSetOption(m_hSession,INTERNET_OPTION_CONNECT_TIMEOUT,
									&dwTimeout,sizeof(dwTimeout));
						
		ret = SUCCESS;
	}
	else ret = BAD_URL;

	return(ret);
}

// Close the WinInet session
void CInternetDownload::CloseSession()
{
	::InternetCloseHandle(m_hSession);
}

//////////////////////
// Private operations
//////////////////////

// Gets the specified file from the web server
CInternetDownload::RESULTS CInternetDownload::DoGet(CString& strURL, BYTE **pbyBuffer, int& nLen, 
											BOOL bIsTextPage)
{
	CInternetDownload::RESULTS nRetCode = UNKNOWN_ERROR;
	CString strTempURL = strURL;
	HINTERNET hConnect = NULL;
	HINTERNET hURL = NULL;
   
    try
	{
		// Initalize returned data count
		nLen = 0;
		
		// Make sure that we have the proper protocol prefix
		strTempURL.MakeLower();
		if(strTempURL.Find(szHttp) < 0)
		{
			strTempURL = szHttp+strURL;
			strURL = szHttp+strURL;
		}
		else strTempURL = strURL;

		// Make sure this URL looks valid
		CString strServer,strObject,strUser,strPassword;
		INTERNET_PORT nPort;
		DWORD dwServiceType;

		// Bail if it doesn't look okay
		strTempURL.SpanExcluding("#");
		if(!AfxParseURLEx(strTempURL,dwServiceType,strServer,strObject,nPort,
						strUser,strPassword,ICU_NO_ENCODE))
			return(CInternetDownload::BAD_URL);

		// Establish a server connection
		hConnect = ::InternetConnect(m_hSession,strServer,
                                          INTERNET_INVALID_PORT_NUMBER,
                                          "",
                                          "",
                                          INTERNET_SERVICE_HTTP,
                                          0,
                                          0) ;

		// Open an HTTP protocol session
		strObject = strObject.SpanExcluding("#");
		const char *szTempX[2] = {szHeaders,NULL};
		hURL = ::HttpOpenRequest(hConnect,"GET",strObject,
									HTTP_VERSION,NULL,
                                    szTempX,dwHttpRequestFlags,0) ;

		// Send the "get" request
 		::HttpSendRequest(hURL,NULL,0,0,0);

		// If it failed, then get out now
	    if(hURL == NULL) 
			return(CInternetDownload::BAD_URL);

		// Check the return code
		DWORD dwRet, dwLen;
		char szTemp[500];
		dwLen = sizeof(szTemp);
		::HttpQueryInfo(hURL,HTTP_QUERY_STATUS_CODE,szTemp,&dwLen,NULL);
		dwRet = (DWORD) atoi(szTemp);
		dwLen = sizeof(szTemp);
		
		m_dwRet = dwRet;

		// Was this page redirected?
		if(dwRet == HTTP_STATUS_MOVED || dwRet == HTTP_STATUS_REDIRECT ||
			       dwRet == HTTP_STATUS_REDIRECT_METHOD)
		{                  
			// Yep...get the new base location
			CString strNewLocation;
			::HttpQueryInfo(hURL,HTTP_QUERY_LOCATION,NULL,&dwLen,0);
			::HttpQueryInfo(hURL,HTTP_QUERY_LOCATION,
						strNewLocation.GetBufferSetLength(dwLen), 
						&dwLen,0);
			strNewLocation.ReleaseBuffer(dwLen);

			// Make sure that the new address contains a server name too
			CString strNewServer;
			AfxParseURLEx(strNewLocation,dwServiceType,strNewServer,strObject,nPort,
							strUser,strPassword,ICU_NO_ENCODE);

			// Is the server name missing for some reason??
			if(strNewServer.IsEmpty())
			{
				// Yes, add it back in
				CString strTempLocation = strServer;
				if(strNewLocation.Left(1) != "/")
					strTempLocation += "/";
				strTempLocation += strNewLocation;
				strNewLocation = strTempLocation;
			}

			// Save the new location
			strURL = strNewLocation;

			::InternetCloseHandle(hURL);
			::InternetCloseHandle(hConnect);
			return(LOCATION_MOVED);
		}
		else if(dwRet == HTTP_STATUS_REQUEST_TIMEOUT || 
					dwRet == HTTP_STATUS_GATEWAY_TIMEOUT ||
					dwRet == HTTP_STATUS_NOT_FOUND)
		{
			Sleep(500L);
			::InternetCloseHandle(hURL);
			::InternetCloseHandle(hConnect);
			return(TIMEOUT);
		}
		else if(dwRet == HTTP_STATUS_OK)
		{
			// Get the data for the file
			BYTE *pbyTempBuffer = *pbyBuffer;
			DWORD dwTotalBytes = 0;
			DWORD dwBytesRead;
			BOOL bOkay = TRUE;

			// Find out how much data we have
			dwLen = sizeof(szTemp);
			::HttpQueryInfo(hURL,HTTP_QUERY_CONTENT_LENGTH,szTemp,&dwLen,NULL);
			dwLen = (DWORD) atol(szTemp);

			// Just make sure we didn't get a stupid length value back
			if(dwLen <= 0) 
				dwLen = 10000;

			// Keep reading data until we've gotten it all
			while(bOkay)
			{
				// Read the data
				bOkay = ::InternetReadFile(hURL,pbyTempBuffer,dwLen,&dwBytesRead);

				// Add to the counts
				if(bOkay && dwBytesRead > 0 && dwTotalBytes < MAX_INET_BUFFER-1)
				{
					dwTotalBytes += dwBytesRead;
					pbyTempBuffer += dwBytesRead;
				}
				else break;
			}

			// NULL terminate the buffer
			pbyTempBuffer[0] = '\0';
			nLen = dwTotalBytes;

			// Close the file
			::InternetCloseHandle(hURL);
			::InternetCloseHandle(hConnect);

			return(SUCCESS);
		}
	}
	catch(...)
	{
		// Fatal error, just get out
		if(hURL) 
			::InternetCloseHandle(hURL);

		if(hConnect)
			::InternetCloseHandle(hConnect);

		return(UNKNOWN_ERROR);
	}
	return (UNKNOWN_ERROR);
}

// Saves the page in memory to the specified file
CInternetDownload::RESULTS CInternetDownload::SaveFile(CString& strFileName, LPCTSTR lpszDirectory,
								BYTE *pbyBuffer, int nLen)
{
	CFile fileOut;
	CFileException ex;
	CString strTempName = lpszDirectory+strFileName;
	strTempName = strTempName.SpanExcluding("#");

	// Open the local file for create 
	if(fileOut.Open(strTempName,CFile::modeCreate|CFile::modeWrite,&ex))
	{
		// Write the data
		fileOut.Write(pbyBuffer,nLen);

		// Close the file
		fileOut.Close();
	}
	else return(BAD_FILENAME);

	return(SUCCESS);
}

/////////////////////
// Public operations
/////////////////////

// Retrieves a page from the web server by calling DoGet().  Also handles
// redirection to other servers as well as retries.
CInternetDownload::RESULTS CInternetDownload::GetPage(CString& strURL, BYTE **pbyBuffer, int& nLen,
									BOOL bRedirectOkay)
{
	int nRetries = 2;
	CInternetDownload::RESULTS ret;

	do 
	{
		// Get the page
		ret = DoGet(strURL,pbyBuffer,nLen,TRUE);
	}
	while(nRetries-- && ((ret == LOCATION_MOVED && bRedirectOkay) || 
							ret == TIMEOUT));

	return(ret);
}

// Retrieves a file from the web server by calling DoGet().  Handles
// redirection to other web servers as well as retries.
CInternetDownload::RESULTS CInternetDownload::GetFile(CString& strURL, BYTE **pbyBuffer, int& nLen)
{
	int nRetries = 2;
	CInternetDownload::RESULTS ret;

	do 
	{
		// Get the file
		ret = DoGet(strURL,pbyBuffer,nLen,FALSE);
	}
	while(nRetries-- && (ret == LOCATION_MOVED || ret == TIMEOUT));

	return(ret);
}

// Reset the "tie breaker" filename counter used by GenerateUniqueFileName().
void CInternetDownload::ResetUniqueCount()
{
	m_nUniqueCount = 0;
}

// Generates a unique filename for the specified file by searching through
// the specified list of downloaded files and looking for a match.  If one
// is found a unque name is generated by taking the old name and appending
// "__x" to the main part of the filename (where x is m_nUniqueCount).
void CInternetDownload::GenerateUniqueFileName(CString& strName, CString& strFileName, 
						MAP_FILES_ARRAY &arrNameMap, BOOL bIsText)
{
	BOOL bFound = FALSE;
	MAP_FILES entry;
	CString strTempName = strName;
	strTempName.MakeLower();
	CString strTempFileName;

	// Split apart the URL
	CString strServer,strObject,strUser,strPassword;
	INTERNET_PORT nPort;
	DWORD dwServiceType;
	AfxParseURLEx(strName,dwServiceType,strServer,strObject,nPort,strUser,
							strPassword,ICU_NO_ENCODE);

	// Get a valid filename
	strFileName = SplitFileName(strObject,CInternetDownload::FNAME|CInternetDownload::EXT);

	// Is there a filename at all??
	if(strFileName.IsEmpty())
	{
		// No, use a default HTML name or a fatal error name
		if(bIsText)
			strFileName = g_szDefPage;
		else strFileName = g_szUnknown;
	}
	else
	{
		// HTML file??
		if(bIsText)
		{
			// Yes, always make sure it ends in .htm, this assures that things
			// such as Active Server Pages (.asp) are loaded correctly.
			CString strExt = SplitFileName(strFileName,CInternetDownload::EXT);
			strExt.MakeLower();

			if(strExt.Find("#") < 0 && strExt != ".htm" && strExt != ".html")
			{
				strFileName += ".htm";
			}
		}
	}

	// Get the new filename
	strTempFileName = strFileName;
	strTempFileName.MakeLower();
	strTempName.MakeLower();

	MAP_FILES *pEntry;
	CString strPage;

	POSITION pos = arrNameMap.GetStartPosition();

	// Name already there???
	for(int nEntryNum = 0; nEntryNum < arrNameMap.GetCount(); nEntryNum++)
	{
		arrNameMap.GetNextAssoc(pos,strPage,(CObject *&) pEntry);
		if(pos == NULL || pEntry == NULL) break;

		// This page is already in the collection, don't create a name for it
		if(strPage == strTempName)
		{
			strName = strPage;
			strFileName = pEntry->strFileName;
			return;
		}

		// Found a duplicate output filename -- generate a unique one now
		if(pEntry->strFileName == strTempFileName)
		{
			// Get out of the loop now so we don't increment the entry number
			bFound = TRUE;
			break;
		}
	}

	// If we found a duplicate, then make sure we create a unique filename using
	// the m_nUniqueCount.
	if(bFound)
	{
		CString strTemp;
		CString strNewFileName;

		// Find the extension
		int nIndex = strFileName.Find(".");
		if(nIndex >= 0)
			strNewFileName = strFileName.Left(nIndex);
		else strNewFileName = strFileName;

		// Append the tie breaker to the main part of the name
		strTemp.Format("__%d",++m_nUniqueCount);
		strNewFileName += strTemp;
		if(nIndex >= 0)
			strNewFileName += strFileName.Mid(nIndex);

		// Save the new name
		strFileName = strNewFileName;
	}
}

// Parses a filename into the specified parts and returns a CString that
// consists of the specified parts.
CString CInternetDownload::SplitFileName(LPCTSTR lpszPath, int nSplit)
{
	CString strResult;

	char szPath[800],szDrive[800],szFileName[800],szExt[800];
	_splitpath(lpszPath,szDrive,szPath,szFileName,szExt);

	if(nSplit & CInternetDownload::DRIVE)
		strResult += szDrive;
	if(nSplit & CInternetDownload::PATH)
		strResult += szPath;
	if(nSplit & CInternetDownload::FNAME)
		strResult += szFileName;
	if(nSplit & CInternetDownload::EXT)
		strResult += szExt;

	return(strResult);
}

CString CInternetDownload::GetErrorText()
{
	CString strError;

	switch(m_dwRet)
	{
		case HTTP_STATUS_MOVED:
		case HTTP_STATUS_REDIRECT:
		case HTTP_STATUS_REDIRECT_METHOD:
			strError = "Redirected, but not found";
			break;

		case HTTP_STATUS_REQUEST_TIMEOUT:
		case HTTP_STATUS_GATEWAY_TIMEOUT:
			strError = "Timed out on request";
			break;

		case HTTP_STATUS_NOT_FOUND:
		case HTTP_STATUS_BAD_REQUEST:
		case HTTP_STATUS_GONE:
			strError = "Page or file not found";
			break;
	
		case HTTP_STATUS_DENIED:
		case HTTP_STATUS_PAYMENT_REQ:
		case HTTP_STATUS_FORBIDDEN:
			strError = "Access denied";
			break;

		case HTTP_STATUS_PROXY_AUTH_REQ:
			strError = "Proxy authentication required";
			break;

		default:
			strError.Format("WinInet error %d",m_dwRet);
			break;
	}

	return(strError);
}