udp 网络应用程序
Ws2_32.lib
#include#include void main() {
WORD wVersionRequested;
WSADATA wsaData;
int err;
wVersionRequested = MAKEWORD( 1, 1 );
err = WSAStartup( wVersionRequested, &wsaData );
if ( err != 0 ) {
/* Tell the user that we could not find a usable */
/* WinSock DLL. */
return;
}
/* Confirm that the WinSock DLL supports 2.2.*/
/* Note that if the DLL supports versions greater */
/* than 2.2 in addition to 2.2, it will still return */
/* 2.2 in wVersion since that is the version we */
/* requested. */
if ( LOBYTE( wsaData.wVersion ) != 1 ||
HIBYTE( wsaData.wVersion ) != 1 ) {
/* Tell the user that we could not find a usable */
/* WinSock DLL. */
WSACleanup( );
return;
}
/* The WinSock DLL is acceptable. Proceed. */
SOCKET sockSrv = socket(AF_INET,SOCK_DGRAM, 0 ); SOCKADDR_IN addrSrv ; addrSrv.sin_addr.S_un.S_addr = htonl(INADDR_ANY); addrSrv.sin_family = AF_INET; addrSrv.sin_port = htons(6000); bind(sockSrv,(SOCKADDR*)&addrSrv,sizeof(SOCKADDR));
SOCKADDR_IN addrClient; int len = sizeof(SOCKADDR);
char recvBuf[100];
recvfrom(sockSrv, recvBuf,100,0,(SOCKADDR*)&addrClient,&len);
printf("%s/n",recvfrom);
closesocket(sockSrv);
WSACleanup();
}
--------------------------------------
WSAStartup （） 用于加载套接字 1 加载套接字库 2 进行套接字库的版本协商
socket
The socket function creates a socket that is bound to a specific service provider.
SOCKET socket( int af, int type, int protocol ）； 创建套接字， 第一个参数 指点地址组，AF——INET（TCPIP） 第二是 socket 的类型 （socket——stream or socket——dgram）
第三个是 与特定的地址家族相关的协议
Return Values
If no error occurs, socket returns a descriptor referencing the new socket. Otherwise, a value of INVALID_SOCKET is returned, and a specific error code can be retrieved by calling WSAGetLastError.
-----------------------------
The bind function associates a local address with a socket.
int bind( SOCKET s, 要指定的绑定的 socket const struct sockaddr FAR *name, 指定 套接字的本地地址信息 int namelen 本地地址信息 的大小
);
inet_addr
The inet_addr function converts a string containing an (Ipv4) Internet Protocol dotted address into a proper address for the IN_ADDR structure.
unsigned long inet_addr( const char FAR *cp 指定一个以点分十进制根式表示的ip地址 ); 返回一个适合分配给s_addr 的u ——long 类型的数值
Parameters
- cp
- [in] Null-terminated character string representing a number expressed in the Internet standard ".'' (dotted) notation.
The listen function places a socket a state where it is listening for an incoming connection.
int listen( SOCKET s, 套接字描述符 int backlog 等待连接队列的最大长度 );
accept
The accept function permits an incoming connection attempt on a socket.
SOCKET accept( SOCKET s, 套接字已经通过listen 函数将其设为监听状态 struct sockaddr FAR *addr,指向一个缓冲区的指针 该缓冲区用来接收实体地址也就是当客户想服务器发起连接的时候 服务器接收这个连接，保存发起连接的这个客户端的IP 地址信息的端口信息
int FAR *addrlen );
The send function sends data on a connected socket.
int send( SOCKET s, const char FAR *buf, int len, int flags );
Parameters
- s
- [in] Descriptor identifying a connected socket.
- buf
- [in] Buffer containing the data to be transmitted.
- len
- [in] Length of the data in buf.
- flags
- [in] Indicator specifying the way in which the call is made.
-
recv
The recv function receives data from a connected or bound socket.
int recv( SOCKET s, char FAR *buf, int len, int flags );
Parameters
- s
- [in] Descriptor identifying a connected socket.
- buf
- [out] Buffer for the incoming data.
- len
- [in] Length of buf.
- flags
- [in] Flag specifying the way in which the call is made.
-
connect
The connect function establishes a connection to a specified socket.
int connect( SOCKET s, 即将在其上建立连接的那个套接字 const struct sockaddr FAR *name, 设定连接的服务器端的地址信息 int namelen );
Parameters
- s
- [in] Descriptor identifying an unconnected socket.
- name
- [in] Name of the socket to which the connection should be established.
- namelen
- [in] Length of name.
recvfrom
The recvfrom function receives a datagram 数据报and stores 保存 the source address.
int recvfrom( SOCKET s, char FAR* buf, int len, int flags, struct sockaddr FAR *from, int FAR *fromlen );
sendto
The sendto function sends data to a specific destination.
int sendto( SOCKET s, const char FAR *buf, int len, int flags, const struct sockaddr FAR *to, int tolen );
htons 把一个ushort （16）类型的值 从主机字节顺序转换为tcpip 的网络字节序
htonl -----ulong （32）-----------
#include#include void main() {
WORD wVersionRequested;
WSADATA wsaData;
int err;
wVersionRequested = MAKEWORD( 1, 1 );
err = WSAStartup( wVersionRequested, &wsaData );
if ( err != 0 ) {
/* Tell the user that we could not find a usable */
/* WinSock DLL. */
return;
}
/* Confirm that the WinSock DLL supports 2.2.*/
/* Note that if the DLL supports versions greater */
/* than 2.2 in addition to 2.2, it will still return */
/* 2.2 in wVersion since that is the version we */
/* requested. */
if ( LOBYTE( wsaData.wVersion ) != 1 ||
HIBYTE( wsaData.wVersion ) != 1 ) {
/* Tell the user that we could not find a usable */
/* WinSock DLL. */
WSACleanup( );
return;
}
/* The WinSock DLL is acceptable. Proceed. */
SOCKET sockClient= socket(AF_INET,SOCK_DGRAM, 0 );
SOCKADDR_IN addrSrv ;
addrSrv.sin_addr.S_un.S_addr = inet_addr("127.0.0.1");
addrSrv.sin_family = AF_INET; addrSrv.sin_port = htons(6000);
sendto(sockClient,"hello",strlen("hello")+1,0,(SOCKADDR*)&addrSrv,sizeof(SOCKADDR));
closesocket(sockClient);
WSACleanup();
}