FTP服务器与客户端设计与开发

FTP服务器与客户端设计与开发

详细设计

程序包括5个主要功能：

1.服务器的运行：启动和停止FTP服务

2.用户管理：添加用户，删除用户和设置用户权限

3.服务器配置：设置服务器开放端口，最大连接数等

4.运行统计：统计当前服务器运行时期上传下载的流量等等

5.安全设置：允许连接服务器的IP列表，以及禁止访问的IP

服务器的运行模块

功能：负责FTP服务器的运行。

使用类：CFTPServer类，CApplicationDlg类，CListenSocket类，CConnectThread类，CConnectSocket类

各种类的功能：

1.CFTPServer类：是CWnd的子类，作为程序的顶层类，负责实现或者调用各个成员函数

2.CApplicationDlg类：CDialog类的子类，实现程序主窗口。

3.CListenSocket类：负责监听FTP客户端连接，并实现有效连接

https://www.360docs.net/doc/5716938721.html,onnectThread类：负责实现并保证多个连接的有效性。

https://www.360docs.net/doc/5716938721.html,onnectSocket类：实现FTP命令的解析，数据的发送和接收

CFTPServer类

作为服务器的顶层类，实现服务器开始运行时的所有成员函数

申明如下：

class CFTPServer : public CWnd

{

friend CConnectSocket;//CConnectSocket作为其友元类，可以访问内部私有数据成员

public:

void SetGoodbyeMessage(LPCTSTR lpszText);//发送退出信息

void SetWelcomeMessage(LPCTSTR lpszText);//发送欢迎信息

void SetTimeout(int nValue);//设置暂停时间

void SetPort(int nValue);//设置端口

void SetMaxUsers(int nValue);//设置最大连接数

void SetStatisticsInterval(int nValue);//统计时间间隔

BOOL IsActive();//是否有效

void Stop();

BOOL Start();

CFTPServer();

virtual ~CFTPServer();

CUserManager m_UserManager;//用户管理对象

CSecurityManager m_SecurityManager;//安全策略

CFTPServer类

最主要的成员函数是start（）和stop（），分别负责ftp服务器的开始运行和结束运行

函数声明如下：

/********************************************************************/

/* */

/* Function name : Start */

/* Description : Start listining on port 21 and accept new */

/* connections. */

/* */

/********************************************************************/

BOOL CFTPServer::Start()

{

if (m_bRunning)

return FALSE;//如果运行，返回错误标志

// create dummy window for message routing

if (!CWnd::CreateEx(0, AfxRegisterWndClass(0), "FTP Server Notification Sink", WS_POPUP, 0,0,0,0, NULL, 0))

{

AddTraceLine(0, "Failed to create notification window.");

return FALSE;

}

// 开始创建socket

if (m_ListenSocket.Create(m_nPort))

{

// start listening

if (m_ListenSocket.Listen())

{

m_ListenSocket.m_pWndServer = this;

m_bRunning = TRUE;

SetTimer(1, m_nStatisticsInterval, NULL);

AddTraceLine(0, "FTP Server started on port %d.", m_nPort);

return TRUE;

}

}

AddTraceLine(0, "FTP Server failed to listen on port %d.", m_nPort);

// destroy notification window

if (IsWindow(m_hWnd))

DestroyWindow();

m_hWnd = NULL;

return FALSE;

}

/********************************************************************/ /* */ /* Function name : Stop */ /* Description : Stop FTP server. */ /* */ /********************************************************************/ void CFTPServer::Stop()

{

if (!m_bRunning)

return;

// stop statistics timer

KillTimer(1);

m_bRunning = FALSE;

m_ListenSocket.Close();

CConnectThread* pThread = NULL;

// close all running threads

do

{

m_CriticalSection.Lock();

POSITION pos = m_ThreadList.GetHeadPosition();

if (pos != NULL)

{

pThread = (CConnectThread *)m_ThreadList.GetAt(pos);

m_CriticalSection.Unlock();

// save thread members

int nThreadID = pThread->m_nThreadID;

HANDLE hThread = pThread->m_hThread;

AddTraceLine(0, "[%d] Shutting down thread...", nThreadID);

// tell thread to stop

pThread->SetThreadPriority(THREAD_PRIORITY_HIGHEST);

pThread->PostThreadMessage(WM_QUIT,0,0);

// wait for thread to end, while keeping the messages pumping (max 5 seconds)

if (WaitWithMessageLoop(hThread, 5000) == FALSE)

{

// thread doesn't want to stopped

AddTraceLine(0, "[%d] Problem while killing thread.", nThreadID);

// don't try again, so remove

m_CriticalSection.Lock();

POSITION rmPos = m_ThreadList.Find(pThread);

if (rmPos != NULL)

m_ThreadList.RemoveAt(rmPos);

m_CriticalSection.Unlock();

}

else

{

AddTraceLine(0, "[%d] Thread successfully stopped.", nThreadID);

}

}

else

{

m_CriticalSection.Unlock();

pThread = NULL;

}

}

while (pThread != NULL);

AddTraceLine(0, "FTP Server stopped.");

if (IsWindow(m_hWnd))

DestroyWindow();

m_hWnd = NULL;

}

CListenSocket类

用于监听每个客户的连接，CListenSocket类是CAsyncSocket的子类，其成员函数listen 监听来自客户端的连接，当监听到可以接收的socket的时候通过OnAccept函数准备创建有效连接的进程。

函数如下：

void CListenSocket::OnAccept(int nErrorCode)

{

// New connection is being established

CSocket sockit;

// Accept the connection using a temp CSocket object.

Accept(sockit);

// Create a thread to handle the connection. The thread is created suspended so that we can

// set variables in CConnectThread before it starts executing.

CConnectThread* pThread =

(CConnectThread*)AfxBeginThread(RUNTIME_CLASS(CConnectThread),

THREAD_PRIORITY_NORMAL, 0, CREATE_SUSPENDED);

if (!pThread)

{

sockit.Close();

TRACE("Could not create thread\n");

return;

}

CFTPServer *pWnd = (CFTPServer *)m_pWndServer;

// since everything is successful, add the thread to our list pWnd->m_CriticalSection.Lock();

pWnd->m_ThreadList.AddTail(pThread);

pWnd->m_CriticalSection.Unlock();

// save pointer

pThread->m_pWndServer = m_pWndServer;

// Pass the socket to the thread by passing the socket handle. You cannot pass // a CSocket object across threads.

pThread->m_hSocket = sockit.Detach();

// Now start the thread.

pThread->ResumeThread();

｝

CConnectThread类

CConnectThread类负责为每个有效进程创建一个线程，每个进程完成数据传输的所有任务，穿件县城后通过InitInstance完成线程的初始化

BOOL CConnectThread::InitInstance()

{

try

{

// Attach the socket handle to a CSocket object.

// This makes sure that the socket notifications are sent to this thread.

m_ConnectSocket.Attach(m_hSocket);

m_ConnectSocket.m_pThread = this;

CString strIPAddress;

UINT nPort;

m_ConnectSocket.GetPeerName(strIPAddress, nPort);

// notify server that there's a new connection

m_pWndServer->SendMessage(WM_THREADSTART, (WPARAM)this, 0);

if (((CFTPServer *)m_pWndServer)->CheckMaxUsers())

{

m_ConnectSocket.SendResponse("421 Too many users are connected, please try again later.");

PostThreadMessage(WM_QUIT,0,0);

}

else

if (!((CFTPServer *)m_pWndServer)->IsIPAddressAllowed(strIPAddress))

{

m_ConnectSocket.SendResponse("421 Access denied, IP address was rejected by the server.");

PostThreadMessage(WM_QUIT,0,0);

}

else

{

// send welcome message to client

CString strText = ((CFTPServer *)m_pWndServer)->GetWelcomeMessage();

m_ConnectSocket.SendResponse("220 " + strText);

m_nTimerID = ::SetTimer(NULL, 0, 1000, TimerProc);

}

}

catch(CException *e)

{

e->Delete();

}

return TRUE;

}

线程结束以后，通过ExitInstance函数实现资源的释放代码如下：

int CConnectThread::ExitInstance()

{

CFTPServer *pWnd = (CFTPServer *)m_pWndServer;

try

{

pWnd->m_CriticalSection.Lock();

// delete this thread from the linked list

POSITION pos = pWnd->m_ThreadList.Find(this);

if(pos != NULL)

{

pWnd->m_ThreadList.RemoveAt(pos);

}

pWnd->m_CriticalSection.Unlock();

// notify service main loop

pWnd->SendMessage(WM_THREADCLOSE, (WPARAM)this, 0);

}

catch(CException *e)

{

pWnd->m_CriticalSection.Unlock();

e->Delete();

}

return CWinThread::ExitInstance();

}

为了了解传输过程中接收和发送的字节数，使用IncReceivedBytes和IncSentBytes来计算。这两个函数在CConnectSocket类中调用，代码如下：

void CConnectThread::IncSentBytes(int nBytes)

{

m_LastDataTransferTime = CTime::GetCurrentTime();

m_nSentBytes += nBytes;

// notify server class

m_pWndServer->PostMessage(WM_THREADMSG, (WPARAM)0, (LPARAM)nBytes);

}

void CConnectThread::IncReceivedBytes(int nBytes)

{

m_LastDataTransferTime = CTime::GetCurrentTime();

m_nReceivedBytes += nBytes;

// notify server class

m_pWndServer->PostMessage(WM_THREADMSG, (WPARAM)1, (LPARAM)nBytes);

}

CConnectSocket类

每个线程都是通过一个CConnectSocket对象m_ConnectSocket来完成数据的接受和发送。当线程创建成功以后，m_ConnectSocket对象通过OnReceive函数获得数据，然后利用ParseCommand函数来解析其中FTP命令

void CConnectSocket::OnReceive(int nErrorCode)

{

TCHAR buff[BUFFERSIZE];

int nRead = Receive(buff, BUFFERSIZE);

switch (nRead)

{

case 0:

Close();

break;

case SOCKET_ERROR:

if (GetLastError() != WSAEWOULDBLOCK)

{

TCHAR szError[256];

wsprintf(szError, "OnReceive error: %d", GetLastError());

AfxMessageBox (szError);

}

break;

default:

if (nRead != SOCKET_ERROR && nRead != 0)

{

((CConnectThread *)AfxGetThread())->IncReceivedBytes(nRead);

// terminate the string

buff[nRead] = 0;

m_RxBuffer += CString(buff);

GetRxLine();

}

break;

}

CSocket::OnReceive(nErrorCode);

}

ParseCommand函数

是当前程序最重要的一个部分，它根据客户端提交的各种命令进行相应的操作代码如下void CConnectSocket::ParseCommand()

{

static CFTPCommand commandList[] =

{

{TOK_USER, "USER", TRUE},

{TOK_PASS, "PASS", TRUE},

{TOK_CWD, "CWD", TRUE},

{TOK_PWD, "PWD", FALSE},

{TOK_PORT, "PORT", TRUE},

{TOK_PASV, "PASV", FALSE},

{TOK_TYPE, "TYPE", TRUE},

{TOK_LIST, "LIST", FALSE},

{TOK_REST, "REST", TRUE},

{TOK_CDUP, "CDUP", FALSE},

{TOK_RETR, "RETR", TRUE},

{TOK_STOR, "STOR", TRUE},

{TOK_SIZE, "SIZE", TRUE},

{TOK_DELE, "DELE", TRUE},

{TOK_RMD, "RMD", TRUE},

{TOK_MKD, "MKD", TRUE},

{TOK_RNFR, "RNFR", TRUE},

{TOK_RNTO, "RNTO", TRUE},

{TOK_ABOR, "ABOR", FALSE},

{TOK_SYST, "SYST", FALSE},

{TOK_NOOP, "NOOP", FALSE},

{TOK_BYE, "BYE", FALSE},

{TOK_QUIT, "QUIT", FALSE},

{TOK_ERROR, "", FALSE},

};

// parse command

CString strCommand, strArguments;

if (!GetRxCommand(strCommand, strArguments))

{

return;

}

int nCommand;

//查找命令

for (nCommand = TOK_USER; nCommand < TOK_ERROR; nCommand++) {

// found command ?

if (strCommand == commandList[nCommand].m_pszName)

{

// did we expect an argument ?

if (commandList[nCommand].m_bHasArguments && (strArguments == ""))

{

SendResponse("501 Syntax error");

return;

}

break;

}

}

if (nCommand == TOK_ERROR)

{

// command is not in our list

SendResponse("500 Syntax error, command unrecognized.");

return;

}

// no commands are excepted before successfull logged on

if (nCommand > TOK_PASS && !m_bLoggedon)

{

SendResponse("530 Please log in with USER and PASS first.");

return;

}

// proces command

switch(nCommand)

{

// specify username

case TOK_USER:

{

strArguments.MakeLower();

m_bLoggedon = FALSE;

m_strUserName = strArguments;

CString strPeerAddress;

UINT nPeerPort;

GetPeerName(strPeerAddress, nPeerPort);

// tell FTP server a new user has connected

CConnectThread *pThread = (CConnectThread *)m_pThread;

((CFTPServer

*)pThread->m_pWndServer)->m_pEventSink->OnFTPUserConnected(m_pThread->m_nThread ID, m_strUserName, strPeerAddress);

SendResponse("331 Password required for " + strArguments);

}

break;

// specify password

case TOK_PASS:

{

// already logged on ?

if (m_bLoggedon)

{

SendResponse("503 Bad sequence of commands.");

}

else

{

// check user and password

CUser user;

if (theServer.m_UserManager.CheckUser(m_strUserName, strArguments, user))

{

//设置用户主目录

m_strCurrentDir = "/";

// 成功登录提示

m_bLoggedon = TRUE;

SendResponse("230 Logged on");

}

else

SendResponse("530 Login or password incorrect!");

}

}

break;

// change current directory

case TOK_CWD:

{

int nResult = theServer.m_UserManager.ChangeDirectory(m_strUserName, m_strCurrentDir, strArguments);

CString str;

switch(nResult)

{

case 0:

str.Format("250 CWD successful. \"%s\" is current directory.", m_strCurrentDir);

SendResponse(str);

break;

case 1:

str.Format("550 CWD failed. \"%s\": Permission denied.", strArguments);

SendResponse(str);

break;

default:

str.Format("550 CWD failed. \"%s\": directory not found.", strArguments);

SendResponse(str);

break;

}

}

break;

// print current directory

case TOK_PWD:

{

CString str;

str.Format("257 \"%s\" is current directory.", m_strCurrentDir);

SendResponse(str);

}

break;

// specify IP and port (PORT a1,a2,a3,a4,p1,p2) -> IP address a1.a2.a3.a4, port p1*256+p2.

case TOK_PORT:

{

CString strSub;

int nCount=0;

while (AfxExtractSubString(strSub, strArguments, nCount++, ','))

{

switch(nCount)

{

case 1: // a1

m_TransferStatus.m_strRemoteHost = strSub;

m_TransferStatus.m_strRemoteHost += ".";

break;

case 2: // a2

m_TransferStatus.m_strRemoteHost += strSub;

m_TransferStatus.m_strRemoteHost += ".";

break;

case 3: // a3

m_TransferStatus.m_strRemoteHost += strSub;

m_TransferStatus.m_strRemoteHost += ".";

break;

case 4: // a4

m_TransferStatus.m_strRemoteHost += strSub;

break;

case 5: // p1

m_TransferStatus.m_nRemotePort = 256*atoi(strSub);

break;

case 6: // p2

m_TransferStatus.m_nRemotePort += atoi(strSub);

break;

}

}

m_TransferStatus.m_bPassiveMode = FALSE;

SendResponse("200 Port command successful");

break;

}

// switch to passive mode

case TOK_PASV:

{

// delete existing datasocket

DestroyDataSocket();

// create new data socket

m_TransferStatus.m_pDataSocket = new CDataSocket(this, -1);

if (!m_TransferStatus.m_pDataSocket->Create())

{

DestroyDataSocket();

SendResponse("421 Can't create socket");

break;

}

// start listening

m_TransferStatus.m_pDataSocket->Listen();

m_TransferStatus.m_pDataSocket->AsyncSelect();

CString strIP, strTmp;

UINT nPort;

// get our ip address

GetSockName(strIP, nPort);

// Now retrieve the port

m_TransferStatus.m_pDataSocket->GetSockName(strTmp, nPort);

// Reformat the ip

strIP.Replace(".",",");

// tell the client which address/port to connect to

CString str;

str.Format("227 Entering Passive Mode (%s,%d,%d)", strIP, nPort/256, nPort%256);

SendResponse(str);

m_TransferStatus.m_bPassiveMode = TRUE;

break;

}

case TOK_TYPE:

{

SendResponse("200 Type set to " + strArguments);

}

break;

// list current directory

case TOK_LIST:

{

if(!m_TransferStatus.m_bPassiveMode &&

(m_TransferStatus.m_strRemoteHost == "" || m_TransferStatus.m_nRemotePort == -1)) {

SendResponse("503 Bad sequence of commands.");

}

else

{

// if client did not specify a directory use current dir

if (strArguments == "")

{

strArguments = m_strCurrentDir;

}

else

{

// check if argument is file or directory

CString strResult;

int nResult =

theServer.m_UserManager.GetFileName(m_strUserName, strArguments, m_strCurrentDir, FTP_LIST, strResult);

if (nResult == 0)

{

strArguments = strResult;

}

}

CString strListing;

int nResult =

theServer.m_UserManager.GetDirectoryList(m_strUserName, strArguments, strListing);

switch(nResult)

{

case 1:

SendResponse("550 Permission denied");

break;

case 2:

SendResponse("550 Directory not found");

break;

default:

if (!m_TransferStatus.m_bPassiveMode)

{

CDataSocket *pDataSocket = new CDataSocket(this, 0);

pDataSocket->Create();

pDataSocket->SetData(strListing);

pDataSocket->AsyncSelect();

m_TransferStatus.m_pDataSocket = pDataSocket;

if

(!pDataSocket->Connect(m_TransferStatus.m_strRemoteHost,

m_TransferStatus.m_nRemotePort))

{

if (GetLastError() != WSAEWOULDBLOCK)

{

SendResponse("425 Can't open data connection");

break;

}

}

SendResponse("150 Opening data channel for directory list.");

}

else

{

m_TransferStatus.m_pDataSocket->SetData(strListing);

m_TransferStatus.m_pDataSocket->SetTransferType(0);

}

break;

}

}

break;

}

// change to parent directory

case TOK_CDUP:

{

CString strDirectory = "..";

CString str;

int nResult = theServer.m_UserManager.ChangeDirectory(m_strUserName, m_strCurrentDir, strDirectory);

switch(nResult)

{

case 0:

str.Format("250 CWD successful. \"%s\" is current directory.", m_strCurrentDir);

SendResponse(str);

break;

case 1:

str.Format("550 CWD failed. \"%s\": Permission denied.", strDirectory);

SendResponse(str);

break;

case 2:

str.Format("550 CWD failed. \"%s\": directory not found.", strDirectory);

SendResponse(str);

break;

}

}

break;

// retrieve file

case TOK_RETR:

{

if(!m_TransferStatus.m_bPassiveMode &&

(m_TransferStatus.m_strRemoteHost == "" || m_TransferStatus.m_nRemotePort == -1)) {

SendResponse("503 Bad sequence of commands.");

break;

}

CString strResult;

int nResult = theServer.m_UserManager.GetFileName(m_strUserName, strArguments, m_strCurrentDir, FTP_DOWNLOAD, strResult);

switch(nResult)

{

case 1:

SendResponse("550 Permission denied");

break;

case 2:

SendResponse("550 File not found");

break;

default:

if (!m_TransferStatus.m_bPassiveMode)

{

CDataSocket *pDataSocket = new CDataSocket(this, 1);

m_TransferStatus.m_pDataSocket = pDataSocket;

pDataSocket->Create();

pDataSocket->AsyncSelect();

pDataSocket->SetData(strResult);

if

(pDataSocket->Connect(m_TransferStatus.m_strRemoteHost ,m_TransferStatus.m_nRem otePort) == 0)

{

if (GetLastError() != WSAEWOULDBLOCK)

{

SendResponse("425 Can't open data connection");

break;

}

}

SendResponse("150 Opening data channel for file transfer.");

}

else

{

m_TransferStatus.m_pDataSocket->SetData(strResult);

m_TransferStatus.m_pDataSocket->SetTransferType(1);

}

break;

}

break;

}

// client wants to upload file

case TOK_STOR:

{

if(m_TransferStatus.m_bPassiveMode == -1)

{

SendResponse("503 Bad sequence of commands.");

break;

}

if(!m_TransferStatus.m_bPassiveMode &&

(m_TransferStatus.m_strRemoteHost == "" || m_TransferStatus.m_nRemotePort == -1)) {

SendResponse("503 Bad sequence of commands.");

break;

}

CString strResult;

int nResult = theServer.m_UserManager.GetFileName(m_strUserName, strArguments, m_strCurrentDir, FTP_UPLOAD, strResult);

switch(nResult)

{

case 1:

SendResponse("550 Permission denied");

break;

case 2:

SendResponse("550 Filename invalid");

break;

default:

if (!m_TransferStatus.m_bPassiveMode)

{

CDataSocket *pDataSocket = new CDataSocket(this, 2);

m_TransferStatus.m_pDataSocket = pDataSocket;

pDataSocket->Create();

pDataSocket->AsyncSelect();

pDataSocket->SetData(strResult);

if

(pDataSocket->Connect(m_TransferStatus.m_strRemoteHost,

m_TransferStatus.m_nRemotePort) == 0)

{

if (GetLastError() != WSAEWOULDBLOCK)

{

SendResponse("425 Can't open data connection");

break;

}

}

SendResponse("150 Opening data channel for file transfer.");

}

else

m_TransferStatus.m_pDataSocket->SetData(strResult);

m_TransferStatus.m_pDataSocket->SetTransferType(2);

}

break;

}

}

break;

// get file size

case TOK_SIZE:

{

CString strResult;

int nResult = theServer.m_UserManager.GetFileName(m_strUserName, strArguments, m_strCurrentDir, FTP_DOWNLOAD, strResult);

switch(nResult)

{

case 1:

SendResponse("550 Permission denied");

break;

case 2:

SendResponse("550 File not found");

break;

default:

{

CFileStatus status;

CFile::GetStatus(strResult, status);

CString strResponse;

strResponse.Format("213 %d", status.m_size);

SendResponse(strResponse);

break;

}

}

}

break;

// delete file

case TOK_DELE:

{

CString strResult;

int nResult = theServer.m_UserManager.GetFileName(m_strUserName, strArguments, m_strCurrentDir, FTP_DELETE, strResult);

switch(nResult)

{

SendResponse("550 Permission denied");

break;

case 2:

SendResponse("550 File not found");

break;

default:

try

{

CFile::Remove(strResult);

}

catch(CFileException *e)

{

e->Delete();

SendResponse("450 Internal error deleting the file.");

break;

}

SendResponse("250 File deleted successfully");

break;

}

}

break;

// remove directory

case TOK_RMD:

{

CString strResult;

int nResult = theServer.m_UserManager.GetDirectory(m_strUserName, strArguments, m_strCurrentDir, FTP_DELETE, strResult);

switch(nResult)

{

case 1:

SendResponse("550 Permission denied");

break;

case 2:

SendResponse("550 Directory not found");

break;

default:

if (!RemoveDirectory(strResult))

{

if (GetLastError() == ERROR_DIR_NOT_EMPTY)

SendResponse("550 Directory not empty.");

else

SendResponse("450 Internal error deleting the