Linux socket programming-simplest server and client programs

I reviewed the Linux socket programming, wrote the simplest server and client programs, and passed the test. The server-side programs adopt the loop and busy waiting mechanism, which will be changed to multithreading and thread pool mechanism later.

Server programs

#include <cstdlib>#include <iostream>#include <cstring>#include <cstdio>#include <cerrno>#include <sys/types.h>#include <sys/socket.h>#include <netinet/in.h>#include <arpa/inet.h>#include <string>using namespace std;#define BACKLOG 10int main(int argc, char * argv[]){int connfd, sockfd;struct sockaddr_in servaddr;struct sockaddr_in tempaddr;struct sockaddr_in cliaddr;socklen_t clilen;char ip_str[INET_ADDRSTRLEN];int ret_val;socklen_t templen;sockfd = socket(AF_INET, SOCK_STREAM, 0);if(sockfd == -1){perror("socket");exit(1);}bzero(&servaddr, sizeof(servaddr));servaddr.sin_family = AF_INET;servaddr.sin_addr.s_addr = htonl(INADDR_ANY);servaddr.sin_port = 0;ret_val = bind(sockfd,(struct sockaddr *)&servaddr, sizeof(servaddr));if(ret_val == -1){perror("bind");exit(1);}cout<< "the sockfd is "<< sockfd << endl;ret_val = listen(sockfd,BACKLOG);if(ret_val == -1){perror("listen");exit(1);}templen = sizeof(struct sockaddr);ret_val =  getsockname(sockfd, (struct sockaddr *)&tempaddr, &templen);if(ret_val == -1){perror("getsockname");exit(1);}cout<<"Server is listening on port "<< ntohs(tempaddr.sin_port)<<endl;for(;;){clilen = sizeof(cliaddr);connfd = accept(sockfd,(struct sockaddr *) &cliaddr,&clilen);if(connfd == -1){perror("accept");continue;}cout<< " Sever: client "<< inet_ntoa(cliaddr.sin_addr) << " connect"<<endl;close(connfd);}return 0;}

Client Program

#include <cstdlib>#include <cstdio>#include <cstring>#include <sys/types.h>#include <sys/socket.h>#include <netinet/in.h>#include <arpa/inet.h>#include <unistd.h>#include <iostream>using namespace std;int main(int argc, char * argv[]){int sockfd;int conn_ret;struct sockaddr_in servaddr;if(argc != 3){cout<< "Usage : client <address> <port> " <<endl;return 0;}sockfd = socket(AF_INET,SOCK_STREAM,0);if (sockfd == -1){perror("sock");exit(1);}bzero(&servaddr,sizeof(servaddr));servaddr.sin_family = AF_INET;        servaddr.sin_port = htons(atoi(argv[2]));inet_pton(AF_INET,argv[1],&servaddr.sin_addr);conn_ret = connect(sockfd, (struct sockaddr *)&servaddr,sizeof(servaddr));if(conn_ret == -1){perror("connect");}close(sockfd);return 0;}