Linux TCP服务器和客户端学习
socket
这里实现的是单连接的情况,即一个服务器只能连接一个客户端。实现的功能是
服务器端:等待客户端连接,连接后显示客户端发送的数据,并将数据原样发送给客户端。
客户端:连接服务器,然后向服务器发送数据,并回显服务器返回的数据
服务器端
tcp_server.c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h> //inet_ntoa() inet_aton() 前者将网络字节序的IP地址转换为10进制的字符串,后者相反
#include <unistd.h> //close()函数#define DEFAULT_PORT 8000
#define MAXLINE 4096int main(int argc, char *argv[]) {int socket_fd, connect_fd;struct sockaddr_in server_addr; //服务器地址struct sockaddr_in client_addr; //连接的客户端地址char buff[4096];int n;//创建socketsocket_fd = socket(AF_INET, SOCK_STREAM, 0);if(socket_fd == -1) {printf("create socket error: %s(errno:%d)\n", strerror(errno), errno);exit(0);}memset(&server_addr, 0, sizeof(server_addr));server_addr.sin_family = AF_INET;server_addr.sin_addr.s_addr = htonl(INADDR_ANY); //INADDR_ANY 让系统自动获取IP地址server_addr.sin_port = htons(DEFAULT_PORT);//设置端口//将本地地址绑定到套接字上if(bind(socket_fd, (struct sockaddr*)&server_addr, sizeof(server_addr)) == -1) {printf("bind socket error: %s(errno:%d)\n", strerror(errno), errno);exit(0);}//监听是否有客户端连接if(listen(socket_fd, 10) == -1) {printf("listen socket error: %s(errno:%d)\n", strerror(errno), errno);exit(0);}printf("=============waiting for client's request==============\n");//阻塞等待客户端连接connect_fd = accept(socket_fd, (struct sockaddr*)NULL, NULL);if(connect_fd == -1) {printf("accept socket error: %s(errno:%d)\n", strerror(errno), errno);exit(0);}int len;getpeername(connect_fd, (struct sockaddr *)&client_addr, &len);printf("client ip: %s, port: %d\n", inet_ntoa(client_addr.sin_addr), ntohs(client_addr.sin_port));while(1) {//接收客户端发送来的数据n = recv(connect_fd, buff, MAXLINE, 0);if(n <= 0) {printf("client disconnect!!! program exit\n");exit(0);}buff[n] = '\0';// 向客户端发送数据if(send(connect_fd, buff, n, 0) == -1) {perror("send error");//close(connect_fd);exit(0);}//显示输出接收到的数据printf("recv msg from client: %s\n", buff);}close(connect_fd);close(socket_fd);return 0;
}
客户端
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <unistd.h>#define MAXLINE 4096int main(int argc, char *argv[]) {int socket_fd;int n, rec_len;char recvline[4096], sendline[4096];char buf[MAXLINE];struct sockaddr_in servaddr;if(argc != 2) {printf("usage: %s <ipaddress>\n", argv[0]);exit(0);}socket_fd = socket(AF_INET, SOCK_STREAM, 0);if(socket_fd < 0) {printf("create socket error: %s(errno:%d)\n", strerror(errno), errno);exit(0);}memset(&servaddr, 0, sizeof(servaddr));servaddr.sin_family = AF_INET;servaddr.sin_port = htons(8000);if(connect(socket_fd, (struct sockaddr*)&servaddr, sizeof(servaddr)) < 0) {printf("connect socket error: %s(errno:%d)\n", strerror(errno), errno);exit(0);}printf("=============client===============\n");while(1) {printf("send msg to server: \n");fgets(sendline, 4096, stdin);if(send(socket_fd, sendline, strlen(sendline), 0) < 0) {printf("send msg error: %s(errno:%d)\n", strerror(errno), errno);exit(0);}rec_len = recv(socket_fd, buf, MAXLINE, 0);if(rec_len < 0) {perror("recv error\n");exit(1);}buf[rec_len] = '\0';printf("recv from server: %s", buf);}close(socket_fd);return 0;
}