嵌入式第三十五天(网络编程(UDP))

一.目的

Linux下的网络编程:目的:不同主机进程间通信

解决问题:

1.主机与主机之间物理层面必须互通

2.进程与进程间在软件层面必须互通

二.相关概念

1.

2.

5.

6.

7.

三.编程

1.流程

2.相关函数接口

3.示例

使用UPD实现全双工通信:

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<unistd.h>
#include<arpa/inet.h>
#include<pthread.h>int socketfd;
struct sockaddr_in client_addr;
socklen_t addr_len = sizeof(client_addr);void *send_message(void *arg)
{while(1){char buff[1024];fgets(buff,sizeof(buff),stdin);buff[strlen(buff) - 1] = '\0';sendto(socketfd,buff,strlen(buff),0,(struct sockaddr*)&client_addr,addr_len);if(strcmp(buff,"quiet") == 0){break;}}pthread_exit(NULL);
}void *recv_message(void *arg)
{while(1){char buff[1024];int ret = recvfrom(socketfd,buff,sizeof(buff),0,(struct sockaddr*)&client_addr,&addr_len);if(ret > 0){buff[ret] = '\0';printf("客户端:%s\n",buff);if(strcmp(buff,"quiet") == 0){break;}}}pthread_exit(NULL);
}int main(int argc,const char *argv[])
{struct sockaddr_in seraddr;pthread_t send_thread;pthread_t recv_thread;socketfd = socket(AF_INET,SOCK_DGRAM,0);if(socketfd < 0){perror("socket error");return -1;}memset(&seraddr,0,sizeof(seraddr));seraddr.sin_family = AF_INET;seraddr.sin_port = htons(50000);seraddr.sin_addr.s_addr = inet_addr("192.168.19.129");int ret = bind(socketfd,(struct sockaddr*)&seraddr,sizeof(seraddr));if(ret < 0){perror("bind errorr");return -1;}char buff[1024];recvfrom(socketfd,buff,sizeof(buff),0,(struct sockaddr*)&client_addr,&addr_len);printf("客户端已连接\n");pthread_create(&send_thread,NULL,send_message,NULL);pthread_create(&recv_thread,NULL,recv_message,NULL);pthread_join(send_thread,NULL);pthread_join(recv_thread,NULL);close(socketfd);return 0;
}

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<unistd.h>
#include<arpa/inet.h>
#include<pthread.h>int client_socket;
struct sockaddr_in seraddr;void *send_message(void *arg)
{while(1){char buff[1024] = {0};fgets(buff,sizeof(buff),stdin);buff[strlen(buff) - 1] = '\0';sendto(client_socket,buff,strlen(buff),0,(struct sockaddr*)&seraddr,sizeof(seraddr));if(strcmp(buff,"quiet") == 0){break;}}pthread_exit(NULL);
}void *recv_message(void *arg)
{int ret;socklen_t addr_len = sizeof(seraddr);while(1){char buff[1024] = {0};ret = recvfrom(client_socket,buff,sizeof(buff),0,(struct sockaddr*)&seraddr,&addr_len);if(ret > 0){buff[ret] = '\0';printf("服务端:%s\n",buff);if(strcmp(buff,"quiet") == 0){break;}}}pthread_exit(NULL);
}int main(int argc,const char *argv[])
{pthread_t send_thread;pthread_t recv_thread;if((client_socket = socket(AF_INET,SOCK_DGRAM,0)) < 0){perror("sockeet error");return 0;}memset(&seraddr,0,sizeof(seraddr));seraddr.sin_family = AF_INET;seraddr.sin_port = htons(50000);seraddr.sin_addr.s_addr = inet_addr("192.168.19.129");printf("客户端启动\n");sendto(client_socket,"",0,0,(struct sockaddr*)&seraddr,sizeof(seraddr));pthread_create(&send_thread,NULL,send_message,NULL);pthread_create(&recv_thread,NULL,recv_message,NULL);pthread_join(send_thread,NULL);pthread_join(recv_thread,NULL);close(client_socket);return 0;
}

补充:

UDP特点: