C++Winsock将冻结接收数据

我正在用C++中的Code:：Blocks制作一个程序，用Winsocks发送和接收数据，但当我试图接收数据时，我的程序会冻结，请帮忙。我不知道为什么？我在不使用循环的情况下只能得到1行，所以我添加了一个循环，看看是否可以得到更多的行，现在它就冻结了。

#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#include "resource.h"
#include <winsock.h>
using namespace std;
SOCKET mysocket;
SOCKADDR_IN SockAddr;
char buf1[120];
char buf2[120];
char ReadIp[120];
int UsePort;
int n;
HINSTANCE hInst;
BOOL CALLBACK DialogProc(HWND hwndDlg, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
    switch(uMsg)
    {
        case WM_INITDIALOG:
            WSADATA WsaDat;
            WSAStartup(MAKEWORD(1,1), &WsaDat);
            mysocket = socket(AF_INET, SOCK_STREAM, 0);
            return TRUE;
        case WM_CLOSE:
            EndDialog(hwndDlg, 0);
            return TRUE;
        case WM_COMMAND:
            switch(LOWORD(wParam))
            {
                case IDC_BTN_QUIT:
                    EndDialog(hwndDlg, 0);
                    return TRUE;
                case BtnSend:
                    GetDlgItemText(hwndDlg, PacketText, buf2, sizeof(buf2));
                    send(mysocket, buf2, sizeof(buf2), 0);
                    return TRUE;
                case IDC_BTN_TEST:
                    UsePort = GetDlgItemInt(hwndDlg, PortText, NULL, FALSE);
                    GetDlgItemText(hwndDlg, IpText, ReadIp, sizeof(ReadIp));
                    SockAddr.sin_port = htons(UsePort);
                    SockAddr.sin_addr.s_addr=inet_addr(ReadIp);
                    SockAddr.sin_family = AF_INET;
                    connect(mysocket, (SOCKADDR *)(&SockAddr), sizeof(SockAddr));
                    do {
                        n = recv(mysocket, buf1, sizeof(buf1), 0);
                    if (n > 0)
                        SetDlgItemText(hwndDlg, List1, buf1);
                    } while (n > 0);
                    return TRUE;
                    }
    }
    return FALSE;
}

int APIENTRY WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nShowCmd)
{
    hInst = hInstance;
    // The user interface is a modal dialog box
    return DialogBox(hInstance, MAKEINTRESOURCE(DLG_MAIN), NULL, (DLGPROC)DialogProc);
}