vc++ socket实现的支持断点续传的下载器
来源：互联网 发布：帝范译文非知之难 编辑：程序博客网 时间：2024/06/05 09:07
网上找了一堆代码，有用wininet的，还有用socket的，整理了半天，还是觉得socket靠谱。
只支持内存中断点续传。如果要加上在磁盘上断点续传，原理也差不多，不是本文重点。
注释：
1. CByteBufferVector是一个缓存池，动态分配BYTE形数组空间用的。代码略，可以简单看成BYTE数组。
2. GetStringA是一个CString转CStringA的函数，无需多说。
3. 除了win socket基本没有其它依赖，噢对，ATL::CString除外……
头文件：
class CSocketDownloader;/** *下载任务 */class CDownloadTask{ friend class CSocketDownloader;public: CDownloadTask(); CStringA GetUrlA() const; CStringA GetAgnetA() const; void ParseUrl(); int Percentage() const; DWORD RemainTimeSec(DWORD dwTickElapsed, unsigned int uBytesTransferred) const; CString m_strUrl; // 下载地址 CString m_strAgent; // 用户agent int m_nMaxTryCount; // 最多重试次数（重定向不算重试，默认20次） int m_nTimeoutSec; // socket超时（秒，默认10秒） int m_nPort; // 端口（默认80） HWND m_hWnd; // 接收下载进度消息的窗口句柄 LONG *m_pTerminate; // 指向是否中止的标志位，一般由用户界面操作（如点击“取消”按钮）更改此值protected: CStringA m_strAbsoluteUrlA; CStringA m_strQueryA; CStringA m_strHostA; unsigned int m_uReadBytes; unsigned int m_uTotalBytes;};/** *socket实现的断点续传下载器 */class CSocketDownloader{public: CSocketDownloader(); virtual ~CSocketDownloader(); // 下载到一个buffer DWORD DownloadToBuffer(CDownloadTask &task, CByteBufferVector &bufVec); // 下载到一个文件 DWORD DownloadToFile(CDownloadTask &task, CString strOutputFile);protected: DWORD DoDownloadToBuffer(CDownloadTask &task, CByteBufferVector &bufVec); DWORD ConnectServer(const CDownloadTask &task, SOCKET hSocket); DWORD DoDownloadToBufferInner(CDownloadTask &task, CByteBufferVector &bufVec, SOCKET hSocket); int GetSleepSecCount(int nTryCount) const; int GetBufferSize(const CDownloadTask &task) const; CStringA GenerateRequest(CDownloadTask &task) const;};CPP文件：
#include <math.h>#include <time.h>const int BLOCK_SIZE = 1024 * 64;const int DEFAULT_MAX_TRY = 20;const int DEFAULT_TIMEOUT = 10;//////////////////////////////////////////////////////////////////////////// 下载任务//////////////////////////////////////////////////////////////////////////CDownloadTask::CDownloadTask() : m_nPort(INTERNET_DEFAULT_HTTP_PORT), m_nMaxTryCount(DEFAULT_MAX_TRY), m_uReadBytes(0), m_uTotalBytes(0), m_nTimeoutSec(DEFAULT_TIMEOUT), m_hWnd(NULL), m_pTerminate(NULL){}CStringA CDownloadTask::GetUrlA() const{ return GetStringA(m_strUrl);}CStringA CDownloadTask::GetAgnetA() const{ return GetStringA(m_strAgent);}void CDownloadTask::ParseUrl(){ m_strAbsoluteUrlA = m_strHostA = m_strQueryA = ""; CStringA strUrlA = this->GetUrlA(); const char *pUrl = strUrlA; const char *p = pUrl; const char *szHttpHead = "http://"; if (_strnicmp(pUrl, szHttpHead, strlen(szHttpHead)) == 0) { p = pUrl + strlen(szHttpHead); } int nHostLen = 0; const char *q = strchr(p, '/'); if (q != NULL) { nHostLen = q - p; int nPathLen = 0; const char *r = strchr(q, '?'); if (r != NULL) { // 解析query r++; m_strQueryA = r; nPathLen = r - q - 1; } else { nPathLen = strlen(q); } // 解析abs_path m_strAbsoluteUrlA.Append(q, nPathLen); } else { nHostLen = strlen(p); } // 解析host m_strHostA.Append(p, nHostLen); // 解析port const char *r = strchr(m_strHostA, ':'); if (r == 0) { m_nPort = INTERNET_DEFAULT_HTTP_PORT; } else { m_nPort = atoi(r + 1); }}int CDownloadTask::Percentage() const{ return (m_uTotalBytes == 0) ? 0 : (int)((unsigned long long)m_uReadBytes * 100 / (unsigned long long) m_uTotalBytes);}DWORD CDownloadTask::RemainTimeSec( DWORD dwTickElapsed, unsigned int uBytesTransferred ) const{ unsigned long long uTickElapsed = (unsigned long long)dwTickElapsed; unsigned long long uBytes = (unsigned long long)uBytesTransferred; unsigned long long uRemain = (unsigned long long)(m_uTotalBytes - m_uReadBytes); Log(_T("elapsed=%d, get=%d, remain=%d\n"), dwTickElapsed, uBytesTransferred, m_uTotalBytes - m_uReadBytes); return (DWORD)(uTickElapsed * uRemain / (uBytes * CLOCKS_PER_SEC));}//////////////////////////////////////////////////////////////////////////// socket下载器//////////////////////////////////////////////////////////////////////////CSocketDownloader::CSocketDownloader(){}CSocketDownloader::~CSocketDownloader(){}DWORD CSocketDownloader::DownloadToBuffer(CDownloadTask &task, CByteBufferVector &bufVec){ int nTryCount = 0; DWORD dwRet = this->DoDownloadToBuffer(task, bufVec); if (web::THE_REDIRECT != dwRet) { nTryCount++; } while ( dwRet != web::THE_SUCCEED && dwRet != web::THE_USER_CANCELED && nTryCount < task.m_nMaxTryCount ) { int nTime = this->GetSleepSecCount(nTryCount); ::Sleep(nTime); dwRet = this->DoDownloadToBuffer(task, bufVec); if (web::THE_REDIRECT != dwRet) { nTryCount++; } } return dwRet;}DWORD CSocketDownloader::DownloadToFile( CDownloadTask &task, CString strOutputFile ){ CByteBufferVector vec; DWORD dwRet = this->DownloadToBuffer(task, vec); if (web::THE_SUCCEED != dwRet) { return dwRet; } HANDLE hFile = ::CreateFile(strOutputFile, GENERIC_WRITE, 0, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL); if (hFile == INVALID_HANDLE_VALUE) { return web::THE_CREATE_FILE; } BYTE *pBuffer = vec.Ptr(0, task.m_uTotalBytes); DWORD dwBytesWritten = 0; ::WriteFile(hFile, pBuffer, task.m_uTotalBytes, &dwBytesWritten, NULL); ::CloseHandle(hFile); return (dwBytesWritten == task.m_uTotalBytes) ? web::THE_SUCCEED : web::THE_WRITE_FILE;}DWORD CSocketDownloader::DoDownloadToBuffer(CDownloadTask &task, CByteBufferVector &bufVec){ task.ParseUrl(); SOCKET hSocket = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP); if (hSocket == INVALID_SOCKET) { return web::THE_CREATE_SOCKET; } DWORD dwRet = this->ConnectServer(task, hSocket); if (web::THE_SUCCEED != dwRet) { closesocket(hSocket); return dwRet; } dwRet = this->DoDownloadToBufferInner(task, bufVec, hSocket); closesocket(hSocket); return dwRet;}DWORD CSocketDownloader::DoDownloadToBufferInner(CDownloadTask &task, CByteBufferVector &bufVec, SOCKET hSocket){ // 发送请求 CStringA strRequest = this->GenerateRequest(task); int nLen = send(hSocket, strRequest, strRequest.GetLength(), 0); if (nLen <= 0) { return web::THE_SEND_HTTP_HEADER; } // 接收一部分数据（header部分，以"\r\n\r\n"为止） CStringA strRecvBuf; char szRecvBuf[MAX_PATH] = { 0 }; nLen = recv(hSocket, szRecvBuf, MAX_PATH - 1, 0); while (nLen > 0) { szRecvBuf[nLen] = 0; strRecvBuf.Append(szRecvBuf); if (strstr(szRecvBuf, "\r\n\r\n") != NULL) { break; } nLen = recv(hSocket, szRecvBuf, MAX_PATH - 1, 0); } // 找到两个回车换行，即content起始位置。 const char *pData = strstr(szRecvBuf, "\r\n\r\n"); if (pData == NULL) { return web::THE_INVALID_RECV_END; } pData += 4; const char *p = strchr(strRecvBuf, ' '); if (p != NULL) { p++; DWORD dwRet = atoi(p); if (dwRet == HTTP_STATUS_PARTIAL_CONTENT) // 206: 断点续传 { const char *q = strstr(strRecvBuf, "\r\nContent-Length:"); if (q == NULL) { return web::THE_NO_CONTENT_LENGTH; } task.m_uTotalBytes = task.m_uReadBytes + atoi(q + 17); } else if (dwRet == HTTP_STATUS_OK) // 200: 重新下载（服务器不支持断点续传） { const char *q = strstr(strRecvBuf, "\r\nContent-Length:"); if (q == NULL) { return web::THE_NO_CONTENT_LENGTH; } task.m_uTotalBytes = task.m_uReadBytes + atoi(q + 17); // 清除已经下载的内容 task.m_uReadBytes = 0; bufVec.Reset(); } else if (dwRet == HTTP_STATUS_REDIRECT) // 302: 重定向 { const char *q = strstr(strRecvBuf, "\r\nLocation:"); if (q == NULL) { return web::THE_NO_REDIRECT_LOCATION; } q += 12; const char *r = strstr(q, "\r\n"); if (r == NULL) { return web::THE_REDIRECT_INVALID_FORMAT; } int nUrlLen = r - q; CStringA strUrlA; strUrlA.Append(q, nUrlLen); task.m_strUrl = GetString(strUrlA); return web::THE_REDIRECT; } else { return web::THE_INVALID_STAUS_CODE; } } // 复制已传回来的第一部分content int nSize = nLen - (pData - szRecvBuf); BYTE *pBuffer = bufVec.Ptr(task.m_uReadBytes, nSize); memcpy(pBuffer, pData, nSize); task.m_uReadBytes += nSize; // 继续接收http content，即下载内容。 int nBufferSize = this->GetBufferSize(task); pBuffer = bufVec.Ptr(task.m_uReadBytes, nBufferSize); DWORD dwLastTick = 0; // 下载测速 DWORD dwTickStart = ::GetTickCount(); unsigned int uReadBytesStart = task.m_uReadBytes; while (true) { if (::InterlockedCompareExchange(task.m_pTerminate, 1, 1)) { // 用户取消。 return web::THE_USER_CANCELED; } nLen = recv(hSocket, (char *)(pBuffer), nBufferSize, 0); if (nLen < 0) { return web::THE_RECV_FAIL; } else if (nLen == 0) { break; // 接收完成 } task.m_uReadBytes += nLen; if (task.m_uReadBytes == task.m_uTotalBytes) { break; // 接收完成 } nBufferSize = this->GetBufferSize(task); pBuffer = bufVec.Ptr(task.m_uReadBytes, nBufferSize); if (NULL != task.m_hWnd) { DWORD dwTick = ::GetTickCount(); if (dwLastTick == 0 || (dwTick - dwLastTick >= 100)) // 每秒最多发10次消息 { // 发送当前下载进度和剩余时间消息 dwLastTick = dwTick; ::PostMessage(task.m_hWnd, WM_FASTINSTALL_PROGRESS_VALUE, static_cast<WPARAM>(task.Percentage()), static_cast<LPARAM>(task.RemainTimeSec(dwTick - dwTickStart, task.m_uReadBytes - uReadBytesStart)) ); } } } DWORD dwTick = ::GetTickCount(); if (NULL != task.m_hWnd) { ::PostMessage( task.m_hWnd, WM_FASTINSTALL_PROGRESS_VALUE, static_cast<WPARAM>(task.Percentage()), -1 ); } return web::THE_SUCCEED;}DWORD CSocketDownloader::ConnectServer(const CDownloadTask &task, SOCKET hSocket){ PHOSTENT pHostent = gethostbyname(task.m_strHostA); if (pHostent == NULL) { return web::THE_GET_HOST_BY_NAME; } sockaddr_in addrSvr; addrSvr.sin_port = htons((u_short)task.m_nPort); addrSvr.sin_family = AF_INET; addrSvr.sin_addr.s_addr = *(ULONG*)pHostent->h_addr_list[0]; if (SOCKET_ERROR == connect(hSocket, (sockaddr*)&addrSvr, sizeof(addrSvr))) { return web::THE_CONNECT_SOCKET; } int opt = task.m_nTimeoutSec * 1000; if (0 != setsockopt(hSocket, SOL_SOCKET, SO_RCVTIMEO, (char*)&opt, sizeof(opt))) { return web::THE_SET_SOCK_OPT1; } BOOL bKeepAlive = TRUE; int len = sizeof(bKeepAlive); getsockopt(hSocket, SOL_SOCKET, SO_KEEPALIVE, (char*)&bKeepAlive, &len); bKeepAlive = TRUE; if (0 != setsockopt(hSocket, SOL_SOCKET, SO_KEEPALIVE, (char *)&bKeepAlive, sizeof(BOOL))) { return web::THE_SET_SOCK_OPT2; } return web::THE_SUCCEED;}int CSocketDownloader::GetSleepSecCount( int nTryCount ) const{ return (nTryCount + 1) * 1000;}int CSocketDownloader::GetBufferSize( const CDownloadTask &task ) const{ return std::min<int>(BLOCK_SIZE, task.m_uTotalBytes - task.m_uReadBytes);}CStringA CSocketDownloader::GenerateRequest( CDownloadTask &task ) const{ CStringA strRequest; CStringA strTemp; if (task.m_strQueryA.IsEmpty()) { strTemp.Format( "GET %s HTTP/1.1\r\nHOST: %s\r\n", task.m_strAbsoluteUrlA.GetString(), task.m_strHostA.GetString() ); } else { strTemp.Format( "GET %s?%s HTTP/1.1\r\nHOST: %s\r\n", task.m_strAbsoluteUrlA.GetString(), task.m_strQueryA.GetString(), task.m_strHostA.GetString() ); } strRequest.Append(strTemp); strTemp.Format("Range: bytes=%d-\r\n", task.m_uReadBytes); strRequest.Append(strTemp); strTemp.Format("User-Agent: %s\r\n", task.GetAgnetA().GetString()); strRequest.Append(strTemp); strRequest.Append("Accept: */*\r\n"); strRequest.Append("Accept-Encoding: gzip, deflate\r\n"); strRequest.Append("Connection: Keep-Alive\r\n\r\n"); return strRequest;}- vc++ socket实现的支持断点续传的下载器
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