linux socket编程 TCP和UDP实例

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linux中的网络编程通过socket接口实现。Socket既是一种特殊的IO，它也是一种文件描述符。一个完整的Socket都有一个相关描述{协议，本地地址，本地端口，远程地址，远程端口}；每一个Socket有一个本地的唯一Socket号，由操作系统分配。
TCP服务器端

#include <stdio.h>#include <sys/types.h>          /* See NOTES */#include <sys/socket.h>#include <netinet/in.h>#include <string.h>#include <unistd.h>#include <stdlib.h>#include <signal.h>int main(){int server_fd,client_fd;//socket出来的文件描述符struct sockaddr_in server_addr={0};//套接字地址struct sockaddr_in client_addr={0};int addrlen;pid_t pid;int nRead;char acBuf[1024];server_fd=socket(PF_INET,SOCK_STREAM,0);//流式套接字if (server_fd==-1){perror("socket");return -1;}//让地址可复用int yest=1;setsockopt(server_fd,SOL_SOCKET,SO_BROADCAST,&yest,sizeof(yest));//绑定自身地址memset(&server_addr,0,sizeof(struct sockaddr_in));server_addr.sin_family=AF_INET;//ipv4server_addr.sin_port=htons(8888);//字节转换函数server_addr.sin_addr.s_addr=inet_addr("127.0.0.1");if (bind(server_fd,(struct sockaddr *)&server_addr,sizeof(struct sockaddr))==-1){perror("bind");return -1;}//设置半链接数listen(server_fd,10);signal(SIGCHLD,SIG_IGN);//屏蔽子进程结束发出的信号//等待客户端用户的链接请求while(1){memset(&client_addr, 0, sizeof(struct sockaddr_in) );client_fd=accept(server_fd,(struct sockaddr *)&client_addr,&addrlen);//阻塞，等待连接if (client_fd==-1){perror("accept");return -1;}pid=fork();//每连接上一个客户端开一个进程if (pid == -1){perror("fork");return -1;}else if (pid ==0){while (1){memset(acBuf, 0, 1024);nRead=read(client_fd, acBuf, 1024);if (nRead == 0){close(client_fd);exit(0);}write(client_fd, acBuf, nRead);}}close(client_fd);}return 0;}

TCP客户端

#include <stdio.h>#include <sys/types.h>          /* See NOTES */#include <sys/socket.h>#include <netinet/in.h>#include <string.h>int main(){int client_fd;//socket出来的文件描述符struct sockaddr_in addr={0};//套接字地址char acBuf[1024]={0};client_fd=socket(PF_INET,SOCK_STREAM,0);if (client_fd==-1){perror("socket");return -1;}//绑定自身地址memset(&addr,0,sizeof(struct sockaddr_in));addr.sin_family=AF_INET;//ipv4addr.sin_port=htons(8888);//端口addr.sin_addr.s_addr=inet_addr("127.0.0.1");//建立连接connect(client_fd,(struct sockaddr *)&addr,sizeof(struct sockaddr));while(1){memset(acBuf,0,1024);scanf("%s",acBuf);if (strcmp(acBuf, "exit" ) == 0){break;}write(client_fd, acBuf, strlen(acBuf) );memset(acBuf,0,1024);read(client_fd,acBuf,1024);printf("%s\n",acBuf);}//关闭文件描述符close(client_fd);return 0;}

UDP服务器端

#include <stdio.h>#include <sys/types.h>          /* See NOTES */#include <sys/socket.h>#include <netinet/in.h>#include <string.h>#include <unistd.h>#include <stdlib.h>int main(){int server_fd;int nRead;struct sockaddr_in server_addr={0};struct sockaddr_in client_addr={0};socklen_t addrlen;server_fd=socket(PF_INET,SOCK_DGRAM,0);if (server_fd==-1){perror("socket");return -1;}//绑定自身地址memset(&server_addr,0,sizeof(struct sockaddr_in));server_addr.sin_family=AF_INET;server_addr.sin_port=htons(8888);server_addr.sin_addr.s_addr=inet_addr("127.0.0.1");//server_addr.sin_addr.s_addr=INADDR_ANY;nRead=bind(server_fd,(struct sockaddr *)&server_addr,sizeof(struct sockaddr));if(nRead==-1){perror("bind");}char acBuf[1024]="";while(1){memset(acBuf,0,1024);nRead=recvfrom(server_fd,acBuf,1024,0,(struct sockaddr *)&client_addr,&addrlen);printf("%s\n",acBuf);if (nRead==-1){perror("recvfrom");}sendto(server_fd,acBuf,1024,0,(struct sockaddr *)&client_addr,sizeof(struct sockaddr));}return 0;}

UDP客户端

#include <stdio.h>#include <sys/types.h>          /* See NOTES */#include <sys/socket.h>#include <netinet/in.h>#include <string.h>int main(){int client_fd;struct sockaddr_in server_addr={0};struct sockaddr_in client_addr={0};socklen_t addrlen;char acBuf[1024]={0};client_fd=socket(PF_INET,SOCK_DGRAM,0);//数据报套接字if (client_fd==-1){perror("socket");}//地址memset(&client_addr,0,sizeof(struct sockaddr_in));client_addr.sin_family=AF_INET;client_addr.sin_port=htons(8888);client_addr.sin_addr.s_addr=inet_addr("127.0.0.1");while(1){memset(acBuf,0,1024);scanf("%s",acBuf);if (strcmp(acBuf, "exit" ) == 0){break;}sendto(client_fd,acBuf,1024,0,(struct sockaddr *)&client_addr,sizeof(struct sockaddr));printf("waiting..\n");memset(acBuf,0,1024);recvfrom(client_fd,acBuf,1024,0,(struct sockaddr *)&server_addr,&addrlen);printf("%s",acBuf);}close(client_fd);return 0;}

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