用WINSOCK API实现同步非阻塞方式的网络通讯

    前面写了基于SELECT实现的同步阻塞方式的网络通讯，本文将基于EVENT，用代码描述实现同步非阻塞方式的网络通讯。相对于同步阻塞方式来说，同步非阻塞方式可以让更好地让系统有时间处理一些其它动作，比如进度条绘制，虽然同步阻塞方式也可以，但效果比不上非阻塞的。需要明确的是，阻塞和非阻塞是指网络套接字与操作系统底层的网络缓冲区（非套接字缓冲区）之间的通讯方式，使用了EVENT方式，会自动将此方式置非阻塞。好了，俺只讲这么多，具体的见代码注释：

Option Base 0 Option Explicit '* ************************************************** * '* 模块名称：Winsocket.cls '* 模块功能：基于API方式的socket同步非阻塞通讯类 '* 编码：lyserver '* 联系方式：http://blog.youkuaiyun.com/lyserver '* ************************************************** * '---------------------------------------------------- ' Winsock API相关声明 '---------------------------------------------------- Private Const SOCKET_ERROR = -1 Private Const INVALID_SOCKET = -1 Private Const WSA_WAIT_FAILED = -1 Private Const WAIT_OBJECT_0 = 0 Private Const WSA_WAIT_EVENT_0 = 0 Private Const WSA_WAIT_TIMEOUT = &H102 Private Const WSAEWOULDBLOCK = 10035 Private Const WSAECONNABORTED = 10053 Public Enum ProtocolConstants IPPROTO_TCP = 6 IPPROTO_UDP = 17 End Enum Private Const INADDR_ANY = &H0 Private Const INADDR_NONE = -1 Private Const SOCK_STREAM = 1 Private Const SOCK_DGRAM = 2 Private Const AF_INET = 2 Private Const O_NONBLOCK = &H4 Private Const FD_NONE = &H0 Private Const FD_READ = &H1 Private Const FD_WRITE = &H2 Private Const FD_ACCEPT = &H8 Private Const FD_CONNECT = &H10 Private Const FD_CLOSE = &H20 Private Type HostEnt hName As Long hAliases As Long hAddrType As Integer hLength As Integer hAddrList As Long End Type Private Const MAX_WSADescription = 256 Private Const MAX_WSASYSStatus = 128 Private Type WSAData wVersion As Integer wHighVersion As Integer szDescription(MAX_WSADescription - 1) As Byte szSystemStatus(MAX_WSASYSStatus - 1) As Byte wMaxSockets As Long wMaxUDPDG As Long dwVendorInfo As Long End Type Private Type sockaddr sin_family As Integer sin_port As Integer sin_addr As Long sin_zero(7) As Byte End Type Private Const FD_MAX_EVENTS = 10 Private Type WSANETWORKEVENTS lNetworkEvents As Long iErrorCode(FD_MAX_EVENTS - 1) As Long End Type Private Declare Function WSAStartup Lib "ws2_32.dll" (ByVal wVersion As Long, lpWSAD As WSAData) As Long Private Declare Function WSACleanup Lib "ws2_32.dll" () As Long Private Type WSAOVERLAPPED Internal As Long InternalHigh As Long Offset As Long OffsetHigh As Long hEvent As Long End Type Private Type WSABUF Length As Long pszBuf As Long End Type Private Declare Function WSASend Lib "ws2_32.dll" (ByVal s As Long, ByRef lpBuffers As WSABUF, ByVal dwBufferCount As Long, ByRef lpNumberOfBytesSent As Long, ByVal dwFlags As Long, lpOverlapped As WSAOVERLAPPED, ByVal lpCompletionRoutine As Long) As Long Private Const WSA_IO_PENDING = 997 Private Declare Function WSARecv Lib "ws2_32.dll" (ByVal hSocket As Long, ByRef lpBuffers As WSABUF, ByVal dwBufferCount As Long, ByRef lpNumberOfBytesRecvd As Long, ByRef lpFlags As Long, ByRef lpOverlapped As WSAOVERLAPPED, ByVal lpCompletionRoutine As Long) As Long Private Declare Function WSAGetOverlappedResult Lib "ws2_32.dll" (ByVal hSocket As Long, ByRef lpOverlapped As WSAOVERLAPPED, ByVal lpcbTransfer As Long, ByVal fWait As Long, ByRef lpdwFlags As Long) As Long Private Const FD_SETSIZE = 64 Private Type fd_set fd_count As Long fd_array(63) As Long End Type Private Type timeval tv_sec As Long tv_usec As Long End Type Private Declare Function WSAEventSelect Lib "ws2_32.dll" (ByVal s As Long, ByVal hEventObject As Long, ByVal lNetworkEvents As Long) As Long Private Declare Function WSACreateEvent Lib "ws2_32.dll" () As Long Private Declare Function WSAResetEvent Lib "ws2_32.dll" (ByVal hEvent As Long) As Long Private Declare Function WSASetEvent Lib "ws2_32.dll" (ByVal hEvent As Long) As Long Private Declare Function WSACloseEvent Lib "ws2_32.dll" (ByVal hEvent As Long) As Long Private Declare Function WSAGetLastError Lib "ws2_32" () As Long Private Declare Function WSAEnumNetworkEvents Lib "ws2_32.dll" (ByVal s As Long, ByVal hEventOjbect As Long, lpNetWorkEvents As WSANETWORKEVENTS) As Long Private Declare Function WSAWaitForMultipleEvents Lib "ws2_32.dll" (ByVal cEvents As Long, ByRef lphEvents As Long, ByVal fWaitAll As Boolean, ByVal dwTimeout As Long, ByVal fAlertable As Boolean) As Long Private Declare Function WSAIsBlocking Lib "ws2_32.dll" () As Long Private Declare Function WSACancelBlockingCall Lib "ws2_32.dll" () As Long Private Declare Function socket Lib "ws2_32.dll" (ByVal af As Long, ByVal s_type As Long, ByVal protocal As Long) As Long Private Declare Function selectAPI Lib "ws2_32" Alias "select" (ByVal nfds As Long, ByVal readfds As Long, ByVal wrITefds As Long, ByVal exceptfds As Long, timeout As timeval) As Long Private Declare Function bindAPI Lib "ws2_32.dll" Alias "bind" (ByVal s As Long, addr As sockaddr, ByVal namelen As Long) As Long Private Declare Function listenAPI Lib "ws2_32.dll" Alias "listen" (ByVal s As Long, ByVal backlog As Long) As Integer Private Declare Function acceptAPI Lib "ws2_32.dll" Alias "accept" (ByVal s As Long, ByRef addr As sockaddr, ByRef namelen As Long) As Long Private Declare Function closesocket Lib "ws2_32.dll" (ByVal s As Integer) As Integer Private Declare Function connectAPI Lib "ws2_32.dll" Alias "connect" (ByVal s As Long, ByRef Name As sockaddr, ByVal namelen As Long) As Long Private Declare Function recv Lib "ws2_32.dll" (ByVal s As Long, buf As Any, ByVal buflen As Long, ByVal flags As Long) As Long Private Declare Function Send Lib "ws2_32.dll" Alias "send" (ByVal s As Long, buf As Any, ByVal buflen As Long, ByVal flags As Long) As Long Private Declare Function htons Lib "ws2_32.dll" (ByVal hostshort As Long) As Integer Private Const TCP_NODELAY = &H1& Private Const SO_LINGER = &H80& Private Type LINGER_STRUCT l_onoff As Integer l_linger As Integer End Type Private Const SO_MAX_MSG_SIZE As Long = &H2003 Private Const SOL_SOCKET = 65535 Private Const SO_SNDBUF = &H1001 ' Send buffer size. Private Const SO_RCVBUF = &H1002 Private Const SO_SNDTIMEO = &H1005 Private Const SO_RCVTIMEO = &H1006 Private Declare Function setsockopt Lib "ws2_32.dll" (ByVal s As Long, ByVal level As Long, ByVal optname As Long, optval As Any, ByVal optlen As Long) As Long Private Declare Function getsockopt Lib "ws2_32.dll" (ByVal s As Long, ByVal level As Long, ByVal optname As Long, optval As Any, optlen As Long) As Long Private Const FIONBIO = &H8004667E Private Const FIOASYNC = &H8004667D Private Declare Function ioctlsocket Lib "ws2_32.dll" (ByVal s As Long, ByVal cmd As Long, argp As Long) As Long Private Declare Function inet_addr Lib "ws2_32.dll" (ByVal cp As String) As Long Private Declare Function inet_ntoa Lib "wsock32.dll" (ByVal addr As Long) As Long Private Declare Function gethostname Lib "ws2_32.dll" (ByVal szHost As String, ByVal dwHostLen As Long) As Long Private Declare Function gethostbyname Lib "ws2_32.dll" (ByVal hostname As String) As Long '---------------------------------------------------- ' ICMP协议API相关声明 '---------------------------------------------------- Private Type ICMP_ECHO_REPLY Address As Long Status As Long RoundTripTime As Long DataSize As Long Reserved As Integer ptrData As Long Options(7) As Byte Data As String * 250 End Type Private Const ICMP_SUCCESS = 0 Private Declare Function IcmpCreateFile Lib "icmp.dll" () As Long Private Declare Function IcmpSendEcho Lib "icmp.dll" (ByVal IcmpHandle As Long, ByVal DestinationAddress As Long, ByVal RequestData As String, ByVal RequestSize As Long, ByVal RequestOptions As Long, ReplyBuffer As ICMP_ECHO_REPLY, ByVal ReplySize As Long, ByVal timeout As Long) As Long Private Declare Function IcmpCloseHandle Lib "icmp.dll" (ByVal IcmpHandle As Long) As Long '---------------------------------------------------- ' 辅助API声明 '---------------------------------------------------- Private Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" (Destination As Any, Source As Any, ByVal Length As Long) Private Const QS_HOTKEY = &H80 Private Const QS_KEY = &H1 Private Const QS_MOUSEBUTTON = &H4 Private Const QS_MOUSEMOVE = &H2 Private Const QS_PAINT = &H20 Private Const QS_POSTMESSAGE = &H8 Private Const QS_SENDMESSAGE = &H40 Private Const QS_TIMER = &H10 Private Const QS_ALLINPUT = (QS_SENDMESSAGE Or QS_PAINT Or QS_TIMER Or QS_POSTMESSAGE Or QS_MOUSEBUTTON Or QS_MOUSEMOVE Or QS_HOTKEY Or QS_KEY) Private Const QS_MOUSE = (QS_MOUSEMOVE Or QS_MOUSEBUTTON) Private Const QS_INPUT = (QS_MOUSE Or QS_KEY) Private Const QS_ALLEVENTS = (QS_INPUT Or QS_POSTMESSAGE Or QS_TIMER Or QS_PAINT Or QS_HOTKEY) Private Declare Function GetQueueStatus Lib "user32" (ByVal qsFlags As Long) As Long Private Declare Function SafeArrayGetDim Lib "oleaut32.dll" (ByRef saArray() As Any) As Long Private Declare Function GetTickCount Lib "kernel32" () As Long Private Declare Function WaitForSingleObject Lib "kernel32" (ByVal hHandle As Long, ByVal dwMilliseconds As Long) As Long Private Declare Sub Sleep Lib "kernel32" (ByVal dwMilliseconds As Long) '---------------------------------------------------- ' 类错误常量声明 '---------------------------------------------------- Public Enum skcErrorConstants sckInvalidAddress = 1001 skcConnectTimeout = 1002 sckSendTimeout = 1003 sckRecvTimeout = 1004 sckDisconnect = 1005 End Enum '---------------------------------------------------- ' 类事件声明 '---------------------------------------------------- Public Event OnSending(ByVal TotalBytes As Long, ByVal SentBytes As Long, ByRef Cancel As Boolean) Public Event OnError(ByVal lngErrorCode As skcErrorConstants, ByVal strDescription As String) '---------------------------------------------------- ' 类属性变量声明 '---------------------------------------------------- Dim m_lngProtocol As ProtocolConstants '---------------------------------------------------- ' 用户自定义模块变量 '---------------------------------------------------- Dim m_blnCancel As Boolean '是否中止标志 Dim m_blnBusy As Boolean '套接字是否处于Busy状态 Dim m_blnInitial As Boolean 'Winsock函数库初始化标志 Dim m_hSocket As Long '套接字句柄 Dim m_hEvent As Long '套接字事件监听对象句柄 Dim m_lngEvents As Long '套接字事件代码 Dim SEND_BUFFER_SIZE As Long '套接字发送缓冲区大小 Dim RECV_BUFFER_SIZE As Long '套接字接收缓冲区大小 '---------------------------------------------------- ' 函数功能：类初始化 '---------------------------------------------------- Private Sub Class_Initialize() Dim WSAD As WSAData Dim lngVersionRequested As Long '初始化SOCKET函数库 lngVersionRequested = &H202 WSAStartup lngVersionRequested, WSAD m_blnInitial = (WSAD.wVersion = lngVersionRequested) '初始化默认通讯协议 m_lngProtocol = IPPROTO_TCP '设置套接字默认值 m_hSocket = INVALID_SOCKET End Sub '---------------------------------------------------- ' 函数功能：类被销毁 '---------------------------------------------------- Private Sub Class_Terminate() Disconnect WSACleanup End Sub '---------------------------------------------------- ' 属性功能：获得和设置通讯协议 ' 参数说明：无 '---------------------------------------------------- Public Property Get Protocol() As ProtocolConstants Protocol = m_lngProtocol End Property Public Property Let Protocol(ByVal New_Value As ProtocolConstants) m_lngProtocol = New_Value End Property '---------------------------------------------------- ' 属性功能：获得和设置发送缓冲区大小 ' 参数说明：无 '---------------------------------------------------- Public Property Get SendBufferSize() As Long SendBufferSize = SEND_BUFFER_SIZE End Property Public Property Let SendBufferSize(ByVal New_Value As Long) If New_Value < 512 Or New_Value > 65536 Then Exit Property SEND_BUFFER_SIZE = New_Value setsockopt m_hSocket, SOL_SOCKET, SO_SNDBUF, SEND_BUFFER_SIZE, Len(SEND_BUFFER_SIZE) End Property '---------------------------------------------------- ' 属性功能：获得和设置接收缓冲区大小 ' 参数说明：无 '---------------------------------------------------- Public Property Get RecvBufferSize() As Long RecvBufferSize = RECV_BUFFER_SIZE End Property Public Property Let RecvBufferSize(ByVal New_Value As Long) If New_Value < 512 Or New_Value > 65536 Then Exit Property RECV_BUFFER_SIZE = New_Value setsockopt m_hSocket, SOL_SOCKET, SO_RCVBUF, RECV_BUFFER_SIZE, Len(RECV_BUFFER_SIZE) End Property '---------------------------------------------------- ' 函数功能：建立网络连接(仅用于客户端) ' 参数说明：strRemoteHost服务器IP或域名，intRemotePort服务器端口 ' 返 回 值：返回数据接收套接字索引，-1为失败 '---------------------------------------------------- Public Function Connect(ByVal strRemoteHost As String, ByVal intRemotePort As Integer) As Boolean Dim s_addr As sockaddr If Not m_blnInitial Then Exit Function '如果未成功初始化Winsock库则退出 If m_hSocket <> INVALID_SOCKET Or m_blnBusy Then Exit Function '如果套接字已创建或处于Busy状态则退出 If Len(strRemoteHost) = 0 Then Exit Function '如果没有指定远程服务器地址则退出 '填充s_addr s_addr.sin_family = AF_INET s_addr.sin_addr = DomainToIp(strRemoteHost) If s_addr.sin_addr = INADDR_NONE Then '如果地址错误，则抛出错误事件并退出连接 RaiseEvent OnError(sckInvalidAddress, "非法的IP地址或通讯端口!") Exit Function End If s_addr.sin_port = htons(intRemotePort) '创建套接字 m_blnBusy = True m_hSocket = socket(AF_INET, SOCK_STREAM, m_lngProtocol) '创建事件监听对象，并绑定到套接字上 m_hEvent = WSACreateEvent() WSAEventSelect m_hSocket, m_hEvent, FD_CONNECT Or FD_READ Or FD_WRITE Or FD_CLOSE connectAPI m_hSocket, s_addr, Len(s_addr) If CheckStatus(FD_CONNECT) Then '如果连接成功 getsockopt m_hSocket, SOL_SOCKET, SO_SNDBUF, SEND_BUFFER_SIZE, Len(SEND_BUFFER_SIZE) '获得发送缓冲区大小 getsockopt m_hSocket, SOL_SOCKET, SO_RCVBUF, RECV_BUFFER_SIZE, Len(RECV_BUFFER_SIZE) '获得接收缓冲区大小 Connect = True '设置连接成功标志 Else RaiseEvent OnError(skcConnectTimeout, "网络连接超时!") Disconnect End If m_blnBusy = False End Function '---------------------------------------------------- ' 函数功能：断开网络连接。 ' 参数说明：无 ' 返 回 值：True成功断开，False失败 '---------------------------------------------------- Public Function Disconnect() As Boolean If m_hSocket <> INVALID_SOCKET And (Not m_blnBusy) Then m_lngEvents = 0 m_blnCancel = False WSAEventSelect m_hSocket, 0, 0 closesocket m_hSocket '关闭连接 WSACloseEvent m_hEvent '关闭监听对象 m_hSocket = INVALID_SOCKET '设置套接字默认值 Disconnect = True End If End Function '---------------------------------------------------- ' 函数功能：读取接收到的数据 ' 参数说明：varData数据接收缓冲区，可为字节串或字节数组 ' 返 回 值：True表示成功，False表示失败 '---------------------------------------------------- Public Function GetData(ByRef varData As Variant, Optional ByVal lngTimeout As Long = 10000) As Boolean Dim i As Long Dim lngRet As Long Dim bytData() As Byte If m_hSocket = INVALID_SOCKET Or m_blnBusy Then Exit Function '如果套接字无效或处于忙状态则退出 '读取数据 If Not CheckStatus(FD_READ, lngTimeout) Then Exit Function '如果套接字不可读则退出循环 ReDim bytData(RECV_BUFFER_SIZE - 1) '初始化接收缓冲区 lngRet = recv(m_hSocket, bytData(0), RECV_BUFFER_SIZE, 0) '读取数据 If lngRet > 0 Then ReDim Preserve bytData(lngRet - 1) If VarType(varData) = vbString Then varData = StrConv(bytData, vbUnicode) Else varData = bytData End If GetData = True Else Erase bytData End If End Function '---------------------------------------------------- ' 函数功能：发送数据。 ' 参数说明：Data需要发送的数据，可为字符串或字节数组 ' 返 回 值：True表示成功，False表示失败 '---------------------------------------------------- Public Function SendData(ByRef varData As Variant, Optional ByVal lngTimeout As Long = 10000) As Boolean Dim bytData() As Byte Dim lngRet As Long Dim lngDataSize As Long Dim lngBlockSize As Long Dim i As Long If m_hSocket = INVALID_SOCKET Or m_blnBusy Then Exit Function '如果套接字无效或处于忙状态则退出 '将需要发送的数据转换为字节数组 Select Case VarType(varData) Case vbString bytData = StrConv(varData, vbFromUnicode) Case (vbByte Or vbArray) bytData = varData Case Else Exit Function End Select '数据为空时无需发送 If SafeArrayGetDim(bytData) = 0 Then Exit Function m_blnBusy = True '数据分块发送 lngDataSize = UBound(bytData) + 1 '需要发送的数据总数量 For i = 0 To lngDataSize - 1 Step SEND_BUFFER_SIZE '如果用户中断发送则退出 If m_blnCancel Then Exit For '计算分块后待发数据的数量 lngBlockSize = lngDataSize - i If lngBlockSize > SEND_BUFFER_SIZE Then lngBlockSize = SEND_BUFFER_SIZE '检查网络是否可写 CheckStatus FD_WRITE, 60000 '如果用户中断发送则退出 If m_blnCancel Then Exit For '发送数据 lngRet = Send(m_hSocket, bytData(i), lngBlockSize, 0) If lngRet = SOCKET_ERROR Then '出错重发 If WSAGetLastError() = WSAEWOULDBLOCK Then If Not CheckStatus(FD_WRITE, 60000) Then Exit For '套接字不可写则退出数据发送 lngRet = Send(m_hSocket, bytData(i), lngBlockSize, 0) '发送数据 End If ElseIf lngRet = lngBlockSize Then '数据发送成功 RaiseEvent OnSending(lngDataSize, i + lngBlockSize, m_blnCancel) '抛出数据发送事件 If lngBlockSize = lngDataSize - i Then m_lngEvents = (m_lngEvents Or FD_WRITE) Exit For End If Else '数据发送失败 Debug.Print WSAIsBlocking() RaiseEvent OnError(sckSendTimeout, "数据发送超时!") Exit Function End If If GetQueueStatus(QS_MOUSE Or QS_KEY Or QS_PAINT) Then DoEvents '转让控制权 Next SendData = ((lngRet = lngBlockSize) And (m_blnCancel = False)) m_blnCancel = False '重置中止状态 m_blnBusy = False '设置状态为空闲 End Function '---------------------------------------------------- ' 函数功能：中止网络操作 ' 参数说明：无 ' 返 回 值：无 '---------------------------------------------------- Public Sub Cancel() m_blnCancel = True '设置中止状态 End Sub '---------------------------------------------------- ' 函数功能：辅助函数，将或名转换为IP ' 参数说明：strHost服务器名称或IP地址，如果为空表示本地计算机。 ' 返 回 值：32位的IP值，如果域名有多个IP，只返回第一个 '---------------------------------------------------- Private Function DomainToIp(Optional ByVal strHost As String) As Long Dim lpHostent As Long, lpIpList As Long, lngIp As Long Dim udtHostent As HostEnt If Not m_blnInitial Then Exit Function '如果未成功初始化Winsock库则退出 lngIp = INADDR_NONE strHost = Trim(strHost) If Len(strHost) = 0 Then strHost = String(100, vbNullChar) gethostname strHost, Len(strHost) '获得本地计算机名称 strHost = Left(strHost, InStr(strHost, vbNullChar) - 1) Else lngIp = inet_addr(strHost) If lngIp <> INADDR_NONE Then 'strHost参数值为IP地址 DomainToIp = lngIp Exit Function End If End If lpHostent = gethostbyname(strHost & vbNullChar) '根据域名获得IP If lpHostent <> 0 Then CopyMemory udtHostent, ByVal lpHostent, LenB(udtHostent) CopyMemory lpIpList, ByVal udtHostent.hAddrList, 4 CopyMemory lngIp, ByVal lpIpList, 4 '当域名有多个IP地址时，只取第一个IP DomainToIp = lngIp End If End Function '---------------------------------------------------- ' 函数功能：辅助函数，检查套接字指定的状态是否准备就绪 ' 参数说明：lMask需检测的状态掩码，lngTimeout超时(单位为毫秒) ' 返 回 值：True表示就绪，False表示未就绪 '---------------------------------------------------- Private Function CheckStatus(ByRef lMask As Long, Optional ByRef lngTimeout As Long = 10000) As Boolean Dim lngRet As Long Dim lngStartTime As Long Dim udtEvent As WSANETWORKEVENTS If (m_lngEvents And lMask) = 0 Then lngStartTime = GetTickCount() Do lngRet = WSAWaitForMultipleEvents(1, m_hEvent, False, 100, False) If lngRet = 0 Then WSAEnumNetworkEvents m_hSocket, m_hEvent, udtEvent m_lngEvents = (m_lngEvents Or udtEvent.lNetworkEvents) Exit Do End If DoEvents '转让控制权 Loop Until m_blnCancel Or GetTickCount() - lngStartTime > lngTimeout End If m_blnCancel = False '重置中止状态 If (m_lngEvents And lMask) = lMask Then m_lngEvents = (m_lngEvents Xor lMask) CheckStatus = True End If End Function