Windows网络编程使用winsock。Winsock是一个基于Socket模型的API，在Windows系统中广泛使用。
使用Winsock进行网络编程需要包含头文件Winsock2.h，需要使用库ws2_32.lib，包含方法：可以使用语句来告诉编译器连接该库
#pragma comment(lib, “ws2_32.lib”);
如果使用VS，可以通过“项目” --> “XX属性”--> “连接器”-->“输入”--> “附加依赖项”添加ws2_32.lib。 （XX为当前工程名）
● 面向连接的C/S程序工程流程图
使用Winsock API编制的网络应用程序中，在调用任何一个Winsock函数之前都必须检查协议栈安装情况，使用函数WSAStartup()完成操作。
● 一个服务端的例子
void server::startServer()
{
WORD wVersionRequested;
WSADATA wsaData;
wVersionRequested=MAKEWORD(2,2);
if(WSAStartup(wVersionRequested,&wsaData)!=0)
{
//Winsock初始化错误
msgBox.exec();
return;
}
if(wsaData.wVersion!=wVersionRequested)
{
//Winsock版本不匹配
WSACleanup();
return;
}
if ((m_sk = socket(AF_INET, SOCK_STREAM, 0)) == SOCKET_ERROR)
{
WSACleanup();
return;
}
bool ok;
unsigned short port = ui.portLineEdit->text().toInt(&ok, 10);
if (ok == false)
{
//端口输入错误
closesocket(m_sk);
m_sk = -1;
WSACleanup();
return;
}
sockaddr_in addr;
addr.sin_family = AF_INET; //使用互联网际协议，即IP协议
addr.sin_port = htons(port);
addr.sin_addr.S_un.S_addr = htonl(INADDR_ANY);
if (bind(m_sk, (sockaddr *)&addr, sizeof(addr)) == SOCKET_ERROR)
{
//绑定端口失败
closesocket(m_sk);
m_sk = -1;
WSACleanup();
return;
}
if (listen(m_sk, 10) == SOCKET_ERROR)
{
//监听端口失败
closesocket(m_sk);
m_sk = -1;
WSACleanup();
return;
}
updateMsgRecs(tr("等待连接..."));
//创建线程去等待连接
HANDLE h = CreateThread(NULL, 0, &server::acceptProc, (LPVOID)this, 0, 0);
if (h == NULL)
{
closesocket(m_sk);
m_sk = -1;
WSACleanup();
return;
}
CloseHandle(h);
}
● 监听线程函数
DWORD WINAPI server::acceptProc(LPVOID lpParamter)
{
/*server *p_server = (server *)lpParamter;
sockaddr_in client_addr;
int len = sizeof(client_addr);
char msgBuff[256];
int sk;
while (1)
{
if ((sk = ::accept(p_server->sk(), (sockaddr*)&client_addr, &len) )== SOCKET_ERROR)
{
emit p_server->haveNewMsg(QObject::tr("accept 出错"));
break;
}
sprintf(msgBuff, "新连接来自%s", inet_ntoa(client_addr.sin_addr));
emit p_server->haveNewMsg(msgBuff);
emit p_server->newClient(inet_ntoa(client_addr.sin_addr), sk);
}*/
server *p_server = (server *)lpParamter;
int client[FD_SETSIZE];
fd_set allset, rset;
sockaddr_in client_addr;
int len;
int clientfd;
int sockfd;
int i;
for (i=0; i<FD_SETSIZE; i++)
client[i] = -1;
FD_ZERO(&allset);
int listenfd = p_server->sk();
FD_SET(listenfd, &allset);
int nready;
int maxfd = listenfd;
int maxi = -1;
char buff[MAX_LEN+1];
while (1)
{
rset = allset;
nready = select(maxfd+1, &rset, NULL, NULL, NULL);
if (FD_ISSET(listenfd, &rset)) //new connection
{
len = sizeof(client_addr);
if ( (clientfd = ::accept(p_server->sk(), (sockaddr*)&client_addr, &len)) == SOCKET_ERROR)
{
emit p_server->haveNewMsg(QObject::tr("accept 出错"));
break;
}
//找出client数组中第一个为-1的单元存放已经连接的socket
for (i=0; i<FD_SETSIZE; i++)
{
if (client[i] <0)
{
client[i] = clientfd;
break;
}
}
if (i == FD_SETSIZE)
{
emit p_server->haveNewMsg(QObject::tr("error: too many clients!"));
break;
}
//sprintf(buff, "新连接来自%s", inet_ntoa(client_addr.sin_addr));
//emit p_server->haveNewMsg(buff);
emit p_server->newClient(inet_ntoa(client_addr.sin_addr), clientfd);
FD_SET(clientfd, &allset);
if (clientfd > maxfd)
maxfd = clientfd;
if (i>maxi)
maxi = i;
if (--nready <= 0)
continue;
}
for (i=0; i<=maxi; i++)
{
if ( (sockfd = client[i]) < 0)
continue;
if (FD_ISSET(sockfd, &rset))
{
int n;
//客户端已经关闭连接
if ( (n = recv(sockfd, buff, MAX_LEN, 0 )) <= 0)
{
closesocket(sockfd);
FD_CLR(sockfd, &allset);
client[i] = -1;
emit p_server->haveNewMsg(QObject::tr("client closed"));
emit p_server->sClientClose(sockfd);
}
else //收到数据
{
buff[n] = 0;
emit p_server->haveNewMsg( buff, sockfd);
if (--nready <= 0)
break;
}
}
} //for (i=0; i<=maxi; i++)
}
return 0;
}
● 一个客户端的例子
void client::connectServer()
{
WORD wVersionRequested;
WSADATA wsaData;
wVersionRequested=MAKEWORD(2,2);
if(WSAStartup(wVersionRequested,&wsaData)!=0)
{
//Winsock初始化错误
QMessageBox msgBox(QMessageBox::Warning, tr("错误"), tr("Winsock初始化错误"), QMessageBox::Ok, 0);
msgBox.exec();
return;
}
if(wsaData.wVersion!=wVersionRequested)
{
//Winsock版本不匹配
QMessageBox msgBox(QMessageBox::Warning, tr("错误"), tr("Winsock版本不匹配"), QMessageBox::Ok, 0);
msgBox.exec();
WSACleanup();
return;
}
if ((m_sk = socket(AF_INET, SOCK_STREAM, 0)) == SOCKET_ERROR)
{
QMessageBox msgBox(QMessageBox::Warning, tr("错误"), tr("创建socket失败"), QMessageBox::Ok, 0);
msgBox.exec();
WSACleanup();
return;
}
sockaddr_in addr;
addr.sin_family = AF_INET;
bool ok;
unsigned short port = ui.portLineEdit->text().toInt(&ok, 10);
if (ok == false)
{
QMessageBox msgBox(QMessageBox::Warning, tr("错误"), tr("端口输入错误"), QMessageBox::Ok, 0);
msgBox.exec();
closesocket(m_sk);
m_sk = -1;
WSACleanup();
return;
}
addr.sin_port = htons(port);
addr.sin_addr.S_un.S_addr = inet_addr("127.0.0.1");
if (0 == ::connect(m_sk, (sockaddr *)&addr, sizeof(addr)))
{
updateMsgRecs(tr("连接成功..."));
HANDLE h = CreateThread(NULL, 0, &client::recvProc, (LPVOID)this, 0, 0);
CloseHandle(h);
}
else
{
QMessageBox msgBox(QMessageBox::Warning, tr("错误"), tr("连接出错"), QMessageBox::Ok, 0);
msgBox.exec();
closesocket(m_sk);
m_sk = -1;
WSACleanup();
}
}
● winsock APIs
网络连接函数
socket 创建套接字
bind 绑定本机端口
connect 建立连接
listen 监听端口
accept 接受连接
recv, recvfrom 数据接收
send, sendto 数据发送
close, shutdown 关闭套接字
转换函数
inet_addr() 点分十进制数表示的IP地址转换为网络字节序的IP地址
inet_ntoa() 网络字节序的IP地址转换为点分十进制数表示的IP地址
字节顺序转换函数
htonl 4字节主机字节序转换为网络字节序
ntohl 4字节网络字节序转换为主机字节序
htons 2字节主机字节序转换为网络字节序
ntohs 2字节网络字节序转换为主机字节序
网络信息检索函数
gethostname 获得主机名
getpeername 获得与套接口相连的远程协议地址
getsockname 获得套接口本地协议地址
gethostbyname 根据主机名取得主机信息
gethostbyaddr 根据主机地址取得主机信息
getprotobyname 根据协议名取得主机协议信息
getprotobynumber 根据协议号取得主机协议信息
getservbyname 根据服务名取得相关服务信息
getservbyport 根据端口号取得相关服务信息
getsockopt/setsockopt 获取/设置一个套接口选项
ioctlsocket 设置套接口的工作方式