我必须编写一个连接到服务器的WIN32异步套接字客户端应用程序。我可以启动程序，连接到服务器，接收并继续接收数据，但是当我尝试向服务器发送消息时，服务器上没有任何反应。我没有任何套接字错误消息，send（）函数返回正确的发送字节。但服务器看起来似乎没有收到任何东西。我的send（）在FD_READ语句中调用，首先是if语句。我试图将其移动到其他语句（WM_CREATE，FD_WRITE，FD_CONNECT），但仍然是同一个问题。我试图找出错误，从一个mounth看很多论坛，但我没有发现问题。任何帮助将非常感激。这是我的代码示例（我跳过了非常有趣的部分）：
#include <windows.h>
#include <fstream>
#include <sstream>
#include<process.h>
#pragma comment(lib,"ws2_32.lib")
using namespace std;
#define IDC_BUTTON_CONNECT 101 // Button identifiers
#define IDC_EDIT_IP 102 // Edit / Text box identifiers
#define IDC_EDIT_PORT 103
#define IDC_EDIT_DEBUG 104
#define WM_SOCKET 105 // Socket messages structure identifier
HWND hWnd;
HWND hEditIp;
HWND hEditPort;
HWND hDebug;
HWND hButtonConnect;
HANDLE hReadMutex;
SOCKET Socket = NULL;
SOCKADDR_IN SockAddr;
char *ip = "";
char *port = "";
bool connectStatus = FALSE;
char readBuffer[5000];
char id[32];
char version[256];
LPSTR statusText = TEXT("Connecting...");
LRESULT CALLBACK WinProc(HWND hWnd,UINT message,WPARAM wParam,LPARAM lParam);
// WinMain...
// appendTextToEdit function...
// incoming data processing thread (not used yet)...
LRESULT CALLBACK WinProc(HWND hWnd,UINT msg,WPARAM wParam,LPARAM lParam)
{
switch(msg)
{
case WM_CREATE:
{
// Get IP and port from file "config.ini"...
//Create windows for IP, Port and Debug...
// Create "connect" button...
WSADATA WsaDat; // Winsock initialization...
int nResult=WSAStartup(MAKEWORD(2,2),&WsaDat);
if(nResult!=0)
{
statusText=TEXT("Winsock initialization failed");
InvalidateRect(hWnd, NULL, TRUE);
break;
}
Socket=socket(AF_INET,SOCK_STREAM,IPPROTO_TCP); // Creating socket...
if(Socket==INVALID_SOCKET)
{
statusText=TEXT("Socket creation failed");
InvalidateRect(hWnd, NULL, TRUE);
break;
}
nResult=WSAAsyncSelect(Socket,hWnd,WM_SOCKET,(FD_CLOSE|FD_READ|FD_WRITE|FD_CONNECT)); // Select AsyncSocket events...
if(nResult)
{
statusText=TEXT("WSAAsyncSelect failed");
InvalidateRect(hWnd, NULL, TRUE);
break;
}
// Set up our socket address structure...
SockAddr.sin_addr.s_addr=inet_addr(ip);
SockAddr.sin_port=htons(atoi(port));
SockAddr.sin_family=AF_INET;
connect(Socket,(LPSOCKADDR)(&SockAddr),sizeof(SockAddr)); // Connexion command
}
break;
case WM_PAINT:
{
// painting / updating the window...
}
break;
case WM_COMMAND:
switch(LOWORD(wParam))
{
case IDC_BUTTON_CONNECT:
{
if(connectStatus==FALSE) // Avoid to reconnect when already online...
{
// Window repaint with updated text (statusText = global variable)
statusText=TEXT("Connecting...");
InvalidateRect(hWnd, NULL, TRUE);
// Retrieve edit box datas and store to variables and file...
// Saving data to "config.ini" file...
// Reinitializing adress structure with new host adress and port from edit boxes, and reconnect attempt...
SockAddr.sin_addr.s_addr=inet_addr(ip);
SockAddr.sin_port=htons(atoi(port));
SockAddr.sin_family=AF_INET;
connect(Socket,(LPSOCKADDR)(&SockAddr),sizeof(SockAddr));
}
break;
}
break;
}
break;
case WM_SOCKET:
{
switch(WSAGETSELECTEVENT(lParam))
{
case FD_CONNECT:
{
connectStatus = TRUE;
statusText=TEXT("Connected");
}
case FD_READ:
{
appendTextToEdit(hDebug, "FD_READ event...\n");
char *rawVariable = nullptr;
char *next_token = nullptr;
recv(Socket, readBuffer, sizeof(readBuffer), 0);
rawVariable = readBuffer;
if(strstr(rawVariable, "id=") != NULL) // Identifying message sent by the server (starts with id, version, ...) and store the values to variables (working fine)
{
char *label = strtok_s(rawVariable, "=", &next_token);
char *pId = strtok_s(NULL, "\n", &next_token);
rawVariable = strtok_s(NULL, "", &next_token);
strcpy_s(id, pId);
char message[256] = "Qh57=1"; // Setting up message structure... (the server should do an action when it receives "Qh57=1\r\n" but it doesn't...) here is my problem...
appendTextToEdit(hDebug, "Message sent : ");
appendTextToEdit(hDebug, message);
char *endline = "\r\n";
strcat_s(message, endline);
string messageString(message);
int messageLength = ((messageString.length()) - 2); // Get outgoing string length (-2)
int sent = send(Socket, message , messageLength , 0);
char buffer [33]; // Display number of bytes sent...
_itoa_s(sent,buffer,10);
appendTextToEdit(hDebug, " (");
appendTextToEdit(hDebug, buffer);
appendTextToEdit(hDebug, " bytes sent)\n");
}
if( strstr(rawVariable, "version") != NULL)
{
char *label = strtok_s(rawVariable, "=", &next_token);
char *pVersion = strtok_s(NULL, "\n", &next_token);
rawVariable = strtok_s(NULL, "", &next_token);
strcpy_s(version, pVersion);
}
appendTextToEdit(hDebug, "End of FD_READ\n");
}
break;
case FD_WRITE:
{
appendTextToEdit(hDebug, "FD_WRITE event...\n");
appendTextToEdit(hDebug, "End of FD_WRITE\n");
}
break;
case FD_CLOSE:
{
statusText = "Disconnected from server";
connectStatus = FALSE;
InvalidateRect(hWnd, NULL, TRUE);
// SendMessage(hWnd, WM_DESTROY, NULL, NULL); // Final version...
}
break;
}
break;
}
break;
case WM_DESTROY:
{
closesocket(Socket);
WSACleanup();
PostQuitMessage(0);
return 0;
}
break;
}
return DefWindowProc(hWnd,msg,wParam,lParam);
}
答案 0 :(得分：3)
问题是您向服务器发送了不完整的消息，因此它不会执行任何操作。根据您自己在代码中的评论：
the server should do an action when it receives "Qh57=1\r\n" but it doesn't...
它永远不会收到\r\n，因为你永远不会发送它：
char message[256] = "Qh57=1";
...
char *endline = "\r\n";
strcat_s(message, endline); // <-- you do append a CRLF...
string messageString(message);
int messageLength = ((messageString.length()) - 2); // <-- but you subtract the CRLF from the message length...
int sent = send(Socket, message , messageLength , 0); // <-- so the CRLF is not sent!
不要从消息长度中减去CRLF：
int messageLength = messageString.length();
BTW，使用std:string来计算消息长度是浪费内存。您可以改为使用strlen()：
int messageLength = strlen(message);
答案 1 :(得分：0)
流套接字连接对消息边界一无所知。它只传输字节，就像RS232连接一样。如果您仔细阅读recv的文档，您会发现成功的recv调用可以在一个字节和指定的缓冲区大小之间的任何地方“返回”（=复制到缓冲区） - 具体取决于多少数据已经收到。 recv的返回值将告诉您已复制了多少。如果跟随更多数据，则将通过后续recv次呼叫返回该数据。这意味着，如果服务器发送id=3\nversion=10.0.5\nQh57=0\nQs323=-999999\n，您的第一个recv调用可能会返回id=3\nversion=10.0.5\nQh，第二个可能会返回57=0\nQs323=-999999\n。或者你可以用3个块来获得它。或者4.或者甚至一次一个字节。
处理此问题的最简单方法（不幸的是性能非常差）是使用一个字节的缓冲区大小重复调用recv。直到您看到已收到整条消息（在您的示例中，这将是在收到4个\n个字符后。）
首选方式如下：
recv recv返回到“消息程序集缓冲区”