网络编程8

UDP版本的客户端/服务器模型

include <sys/socket.h>

ssize_t recvfrom(int sockfd, void *buff, size_t nbytes, int flags,struct sockaddr *from, socklen_t *addrlen);

ssize_t sendto(int sockfd, const void *buff, size_t nbytes, int flags, const struct sockaddr *to, socklen_t *addrlen);//类似于标准的read和write函数

//前三个参数等同于read和write三个参数，描述符，指向读入或者写出缓冲区的指针和读写字节数

int
main(int argc, char **argv){
int sockfd;
struct sockaddr_in servaddr, cliaddr;
sockfd = Socket(AF_INET,SOCK_DGRAM,0);
bzero(&servaddr, sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
servaddr.sin_port = htons(SERV_PORT);
Bind(sockfd, (SA *) &servaddr, sizeof(servaddr));
dg_echo(sockfd,(SA *) &cliaddr, sizeof(cliaddr));
}//UDP回射服务器程序:main函数

void
dg_echo(int sockfd, SA *pcliaddr, socklen_t clien)
{
int n;
socklen_t len;
char mesg[MAXLINE];
for (;😉{
len = clien;
n = recvfrom(sockfd, mesg, MAXLINE, 0, pcliaddr, &len);
sendto(sockfd, mesg, n, 0, pcliaddr, len);
}
}//dg_echo函数：在数据报套接字上回射文本行