嵌入式 Linux网络编程（三）——UDP编程模型

嵌入式 Linux网络编程（三）——UDP编程模型

socket(...);
bind(...);
while(1)
{
recvfrom(...);
process(...);
sendto(...);
}

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#define PORT  8888
#define BUFFER_SIZE 1024

int main(int argc, char *argv[])
{
int sockfd;
sockfd = socket(AF_INET, SOCK_DGRAM, 0); // 创建udp套接字
if(sockfd < 0)
{
fprintf(stderr, "socket function failed.\n");
exit(-1);
}
struct sockaddr_in server_addr;
bzero(&server_addr, sizeof(server_addr));
server_addr.sin_family = AF_INET;// IPv4
server_addr.sin_port   = htons(PORT);// 端口
server_addr.sin_addr.s_addr = htonl(INADDR_ANY); // ip
// 绑定
int err;
err = bind(sockfd, (struct sockaddr*)&server_addr, sizeof(server_addr));
if(err != 0)
{
fprintf(stderr, "bind function failed.\n");
close(sockfd);
exit(-1);
}
fprintf(stdout, "server runiing on %d\n", PORT);
char recvbuf[BUFFER_SIZE];
struct sockaddr_in client_addr;
while(1)
{
int recvlen;
bzero(&recvbuf, sizeof(recvbuf));
socklen_t len = sizeof(client_addr);
bzero(&client_addr, sizeof(client_addr));
if(strcmp(recvbuf,"exit\n")==0)
break;
if(strcmp(recvbuf,"q\n")==0)
break;
if(strcmp(recvbuf,"quit\n")==0)
break;
// 接收客户端数据
recvlen = recvfrom(sockfd, recvbuf, sizeof(recvbuf), 0, (struct sockaddr*)&client_addr, &len);
fprintf(stdout, "have a new client :%s, port:%d\n", inet_ntoa(client_addr.sin_addr), ntohs(client_addr.sin_port)); // 客户端的ip
printf("message: %s\n", recvbuf);
sendto(sockfd, recvbuf, recvlen, 0, (struct sockaddr*)&client_addr, len);
}
close(sockfd);
return 0;
}

#include <sys/types.h>
#include <sys/socket.h>
#include <stdio.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/shm.h>

#define PORT  8888
#define BUFFER_SIZE 1024

int main()
{
///定义sockfd
int clientsockfd = socket(AF_INET, SOCK_DGRAM, 0);
///定义sockaddr_in
struct sockaddr_in servaddr;
bzero(&servaddr, sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_port = htons(PORT);  ///服务器端口
servaddr.sin_addr.s_addr = inet_addr("192.168.0.200");  ///服务器ip
///连接服务器，成功返回0，错误返回-1
if (connect(clientsockfd, (struct sockaddr *)&servaddr, sizeof(servaddr)) < 0)
{
fprintf(stderr, "connect function failed.\n");
exit(-1);
}
char sendbuf[BUFFER_SIZE];
char recvbuf[BUFFER_SIZE];
bzero(sendbuf, sizeof(sendbuf));
bzero(recvbuf, sizeof(recvbuf));
while (1)
{
fgets(sendbuf, sizeof(sendbuf), stdin);
if(strcmp(sendbuf,"exit\n")==0)
break;
if(strcmp(sendbuf,"q\n")==0)
break;
if(strcmp(sendbuf,"quit\n")==0)
break;
send(clientsockfd, sendbuf, strlen(sendbuf),0); ///发送

recv(clientsockfd, recvbuf, sizeof(recvbuf),0); ///接收

fprintf(stdout, "%s\n", recvbuf);
bzero(sendbuf, sizeof(sendbuf));
bzero(recvbuf, sizeof(recvbuf));
}
close(clientsockfd);
return 0;
}