BSD Sockets 使用的最广泛的网络程序编程方法,主要用于应用程序的编写,用于网络上主机与主机之间的相互通信.

UNIX,Linux,VxWorks均支持BSD Sockets,Windows的Winsock基本上是来自BSD Sockets

Socket分为Stream Sockets和Data Sockets.

Stream Sockets是可靠性的双向数据传输用TCP,如HTTP,FTP等

Data Sockets是不可靠连接用UDP,如多点广播,DHCP,SNMP,RIP等.

　

• TCP服务器端和一个TCP客户端通信的程序过程

　

• UDP服务器端和一个UDP客户端通信的程序过程

 

UDP广播包程序示例

发送UDP广播包，查找本地网络中所有运行SNMP服务设备的IP信息。
winsock, win32控制台程序。

#define SNMP_PORT 161
void SearchIP_In_LAN() 
{ 
WSADATA wsaData; 
SOCKET sockListener;
SOCKADDR_IN saUdpCli,saUdpServ;
BOOL fBroadcast = TRUE;

char sendBuff[40]= //SNMP查询包内容
{ 
'\x30','\x26','\x02','\x01','\x00', 
'\x04','\x06','\x70','\x75','\x62', 
'\x6c','\x69','\x63','\xa0','\x19', 
'\x02','\x01','\x03','\x02','\x01', 
'\x00','\x02','\x01','\x00','\x30', 
'\x0e','\x30','\x0c','\x06','\x08', 
'\x2b','\x06','\x01','\x02','\x01', 
'\x01','\x01','\x00','\x05','\x00' 
}; 
char recvBuff[600]; 
int nSize,err,timeoutnum = 1;;
ULONG HostIpAddr;
int rv; 
int ncount=0; 

if(WSAStartup(MAKEWORD( 2, 2),&wsaData)!=0) 
{
printf("Winsocket start error!\n");
return; 
}

sockListener=socket(AF_INET,SOCK_DGRAM,0); 
err = setsockopt ( sockListener,
SOL_SOCKET,
SO_BROADCAST, 
(CHAR *)&fBroadcast,
sizeof ( BOOL )); 
if ( SOCKET_ERROR == err ) return ;

int TimeOut=10000;

err = setsockopt ( sockListener, 
SOL_SOCKET,
SO_RCVTIMEO,
(CHAR *) &TimeOut,
sizeof (TimeOut)
);
if ( SOCKET_ERROR == err ) return ;

saUdpCli.sin_family = AF_INET; 
saUdpCli.sin_port = htons(0); 
saUdpCli.sin_addr.s_addr = htonl(INADDR_ANY); 
if(bind( sockListener, (SOCKADDR *)&saUdpCli, sizeof(SOCKADDR_IN))!=0) 
{ 
printf("Can't bind socket to local port!Program stop.\n");
return; 
} 

err = gethostname(recvBuff,sizeof(recvBuff));
if ( SOCKET_ERROR == err )
return ;

struct hostent *hp = gethostbyname(recvBuff);
if (!hp) return ;

saUdpServ.sin_family = AF_INET; 

memcpy(&(saUdpServ.sin_addr),hp->h_addr,hp->h_length);
HostIpAddr=ntohl(saUdpServ.sin_addr.s_addr);

saUdpServ.sin_addr.s_addr = htonl ( INADDR_BROADCAST ); 
saUdpServ.sin_port = htons (SNMP_PORT);
nSize = sizeof ( SOCKADDR_IN ); 
if((rv = sendto ( sockListener,
sendBuff,
sizeof(sendBuff),0,
(SOCKADDR *) &saUdpServ,
sizeof ( SOCKADDR_IN )))==SOCKET_ERROR) 
{ 
printf("Send error!\n");
closesocket(*((SOCKET*)sockListener)); 
return; 
} 
printf("Send successful!\n");
do // waiting to receive
{
if((rv=recvfrom ( sockListener,
recvBuff,sizeof(recvBuff),0,
(SOCKADDR *) &saUdpCli,&nSize))==SOCKET_ERROR) 
{ 
if(WSAGetLastError()==WSAETIMEDOUT)
{
if (timeoutnum > 6 ) //Wait for 1 minute.
break;
else
timeoutnum++;
}
}
else
{
CString Ip(inet_ntoa ( saUdpCli.sin_addr ));
printf("\t IP Adress-> %s ",Ip);
} 

}while(TRUE);
closesocket(*((SOCKET*)sockListener)); 
return ;
}

　

网络软件设计框图(个人理解,仅供参考)

　

• 设备管理服务软件架构

　

• 信息家电(IA)的架构

　

　

• 无线移动通信的架构