Linux TCP网络编程示例

#include <sys/types.h> #include <sys/socket.h> #include <arpa/inet.h> #include <netinet/in.h> #include <strings.h> #include <string.h> #include <stdio.h> #include <stdlib.h> #include <errno.h> #include <unistd.h> int main(int argc, char *argv[]) { int sockfd; char buffer[1024]; struct sockaddr_in server_addr; int portnumber, nbytes; if (argc != 3) { fprintf(stderr, "Usage:%s hostname portnumber/n/a", argv[0]); exit(1); } if (inet_aton(argv[1], &server_addr.sin_addr) == 0) { fprintf(stderr, "the hostip is not right!"); exit(1); } if ((portnumber = atoi(argv[2])) < 0) { fprintf(stderr, "Usage:%s hostname portnumber/n/a", argv[0]); exit(1); } // 创建套接字 if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1) { fprintf(stderr, "Socket Error:%s/n/a", strerror(errno)); exit(1); } // 填充服务器的地址信息 server_addr.sin_family = AF_INET; server_addr.sin_port = htons(portnumber); // 向服务器发起连接 if (connect(sockfd, (struct sockaddr *)&server_addr, sizeof(struct sockaddr)) == -1) { fprintf(stderr, "Connect Error:%s/n/a", strerror(errno)); exit(1); } // 连接成功后，从服务器接收信息 if ((nbytes = read(sockfd, buffer, 1024)) == -1) { fprintf(stderr, "Read Error:%s/n", strerror(errno)); exit(1); } buffer[nbytes] = '/0'; printf("I have received:%s/n", buffer); close(sockfd); exit(0); }

 

#include <sys/types.h> #include <sys/socket.h> #include <arpa/inet.h> #include <netinet/in.h> #include <strings.h> #include <string.h> #include <stdio.h> #include <stdlib.h> #include <errno.h> #include <unistd.h> int main(int argc, char *argv[]) { int sockfd, new_fd; struct sockaddr_in server_addr; struct sockaddr_in client_addr; int sin_size, portnumber; char hello[] = "Hello! Are you fine?/n"; if (argc != 2) { fprintf(stderr, "Usage:%s portnumber/a/n", argv[0]); exit(1); } if ((portnumber = atoi(argv[1])) < 0) { fprintf(stderr, "Usage:%s portnumber/a/n", argv[0]); exit(1); } // 创建套接字 if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1) { fprintf(stderr, "Socket error:%s/n/a", strerror(errno)); exit(1); } // 填充服务器的地址结构 bzero(&server_addr, sizeof(struct sockaddr_in)); server_addr.sin_family = AF_INET; server_addr.sin_addr.s_addr = htonl(INADDR_ANY); server_addr.sin_port = htons(portnumber); // 套接字绑定地址 if (bind(sockfd, (struct sockaddr *)&server_addr, sizeof(struct sockaddr)) == -1) { fprintf(stderr, "Bind error:%s/n/a", strerror(errno)); exit(1); } // 进入监听状态 if (listen(sockfd, 5) == -1) { fprintf(stderr, "Listen error:%s/n/a", strerror(errno)); exit(1); } while (1) { // 接收客户端的连接 sin_size = sizeof(struct sockaddr_in); if ((new_fd = accept(sockfd, (struct sockaddr *)&client_addr, (socklen_t *)&sin_size)) == -1) { fprintf(stderr, "Accept error:%s/n/a", strerror(errno)); exit(1); } fprintf(stderr, "Server get connection from %s/n", inet_ntoa(client_addr.sin_addr)); if (write(new_fd, hello, strlen(hello)) == -1) { fprintf(stderr, "Write error:%s/n", strerror(errno)); exit(1); } close(new_fd); } close(sockfd); // exit(0); return 0; }