13-基础篇-UDP

UDP是一种无连接的尽最大努力交付的不可靠连接，通信之前无需先建立连接，自然而然，通信之后也就无需再释放连接。

下面是UDP的应用举例

服务端

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 

int main()
{
	int sockfd = socket(AF_INET,SOCK_DGRAM,0);
	assert( sockfd != -1 );

	struct sockaddr_in saddr,caddr;
	memset(&saddr,0,sizeof(saddr));
	saddr.sin_family = AF_INET;
	saddr.sin_port = htons(6000);
	saddr.sin_addr.s_addr = inet_addr("127.0.0.1");

	int res = bind(sockfd,(struct sockaddr*)&saddr,sizeof(saddr));
	assert( res != -1 );

	while( 1 )
	{
		int len = sizeof(caddr);
		char buff[128] = {0};
		recvfrom(sockfd,buff,127,0,(struct sockaddr*)&caddr,&len);
		printf("recv: ip:%s,port:%d,buff=%s\n",inet_ntoa(caddr.sin_addr), ntohs(caddr.sin_port),buff );

		sendto(sockfd,"ok",2,0,(struct sockaddr*)&caddr,sizeof(caddr));
		sleep(1);
	}

	close(sockfd);
}

运行结果

recv: ip:127.0.0.1,port:41821,buff=send!!!!

recv: ip:127.0.0.1,port:41821,buff=send!!!!

recv: ip:127.0.0.1,port:41821,buff=send!!!!

recv: ip:127.0.0.1,port:41821,buff=send!!!!

recv: ip:127.0.0.1,port:41821,buff=send!!!!

recv: ip:127.0.0.1,port:41821,buff=send!!!!

客户端

#include 

#include 
#include 
#include 
#include 
#include 
#include 
#include 

int main()
{
	int sockfd = socket(AF_INET,SOCK_DGRAM,0);
	assert( sockfd != -1 );

	struct sockaddr_in saddr;
	memset(&saddr,0,sizeof(saddr));
	saddr.sin_family = AF_INET;
	saddr.sin_port = htons(6000);
	saddr.sin_addr.s_addr = inet_addr("127.0.0.1");

	while( 1 )
	{
		char buff[128] = "send!!!!\n";

		sendto(sockfd,buff,strlen(buff),0,(struct sockaddr*)&saddr,sizeof(saddr));
		memset(buff,0,128);

		int len = sizeof(saddr);
		recvfrom(sockfd,buff,127,0,(struct sockaddr*)&saddr,&len);

		printf("recv=%s\n",buff);
		sleep(1);
	}

	close(sockfd);

}

运行结果

recv=ok
recv=ok
recv=ok
recv=ok
recv=ok
recv=ok