Linux网络编程-UDP

UDP通信

服务端

• udp_server.c

  /*
  服务端的开发流程：
      1.创建socket
          udp_socket = socket(AF_INET, SOCK_DGRAM, 0);
      2.绑定--bind()
      3.传输数据
          while(1)
          {
              //读取数据
              n = recvfrom(cfd, buf, sizeof(buf), 0, (struct sockaddr *)&client, &len);
  
              //发送数据
              sendto(cfd, buf, n, 0, (struct sockaddr *)&client, len);
          }
      4.关闭socket套接字
          close(cfd);
  */
  //udp服务端
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  #include <sys/types.h>
  #include <unistd.h>
  #include <arpa/inet.h>
  #include <netinet/in.h>
  #include <ctype.h>
  
  int main()
  {
  	//创建socket
  	int cfd = socket(AF_INET, SOCK_DGRAM, 0);
  	if (cfd < 0)
  	{
  		perror("socket error");
  		return -1;
  	}
  
  	//绑定
  	struct sockaddr_in client;
  	struct sockaddr_in serv;
  	bzero(&serv, sizeof(serv));
  	serv.sin_family = AF_INET;
  	serv.sin_port = htons(8888);
  	serv.sin_addr.s_addr = htonl(INADDR_ANY);
  	bind(cfd, (struct sockaddr *)&serv, sizeof(serv));
  
  	int i;
  	int n;
  	char buf[1024];
  	socklen_t len;
  	while (1)
  	{
  		//读取数据
  		memset(buf, 0x00, sizeof(buf));
  		len = sizeof(client);
  		n = recvfrom(cfd, buf, sizeof(buf), 0, (struct sockaddr *)&client, &len);
  
  		//将大写转换为小写
  		for (i = 0; i < n; i++)
  		{
  			buf[i] = toupper(buf[i]);
  		}
  		printf("port=[%d], n=[%d], buf=[%s]\n", ntohs(client.sin_port), n, buf);
  		//发送数据
  		sendto(cfd, buf, n, 0, (struct sockaddr *)&client, len);
  	}
  	//关闭文件描述符
  	close(cfd);
  
  	return 0;
  }

客户端

• udp_client.c

  /*
  客户端的开发流程：
      1.创建socket
          udp_socket = socket(AF_INET, SOCK_DGRAM, 0);
      2.传输数据
          while(1)
          {
              //发送数据
              sendto(cfd, buf, n, 0, (struct sockaddr *)&client, len);
  
              //读取数据
              n = recvfrom(cfd, buf, sizeof(buf), 0, (struct sockaddr *)&client, &len);
          }
      3.关闭socket套接字
          close(cfd);
  */
  //udp客户端
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  #include <sys/types.h>
  #include <unistd.h>
  #include <arpa/inet.h>
  #include <netinet/in.h>
  #include <ctype.h>
  
  int main()
  {
  	//创建socket
  	int cfd = socket(AF_INET, SOCK_DGRAM, 0);
  	if (cfd < 0)
  	{
  		perror("socket error");
  		return -1;
  	}
  
  	struct sockaddr_in serv;
  	serv.sin_family = AF_INET;
  	serv.sin_port = htons(8888);
  	inet_pton(AF_INET, "127.0.0.1", &serv.sin_addr.s_addr);
  
  	int n;
  	char buf[1024];
  	
  	while (1)
  	{
  		//读标准输入数据
  		memset(buf, 0x00, sizeof(buf));
  		n = read(STDIN_FILENO, buf, sizeof(buf));
  
  		//发送数据
  		sendto(cfd, buf, n, 0, (struct sockaddr *)&serv, sizeof(serv));
  
  		//读取数据
  		memset(buf, 0x00, sizeof(buf));
  		n = recvfrom(cfd, buf, sizeof(buf), 0, NULL, NULL);
  		printf("n=[%d], buf=[%s]\n", n, buf);
  	}
  	//关闭文件描述符
  	close(cfd);
  
  	return 0;
  }