Linux网络编程--客户端连接服务器端

 

第一个简单的应用程序，客户端连接服务器端：

#################### server.c####################

 

#include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <errno.h> #include <string.h> #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> #include <arpa/inet.h> #include <sys/wait.h> #include <signal.h> #define MYPORT 3424 // the port users will be connecting to #define BACKLOG 10 // how many pending connections queue will hold void sigchld_handler(int s) {     while(waitpid(-1, NULL, WNOHANG) > 0);//参考：me } int main(void) {     int sockfd, new_fd; // listen on sock_fd, new connection on new_fd     struct sockaddr_in my_addr; // my address information     struct sockaddr_in their_addr; // connector's address information     socklen_t sin_size;     struct sigaction sa;     int yes=1;     if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1) {         perror("socket");         exit(1);     }     if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(int)) == -1) {         perror("setsockopt");         exit(1);     }     my_addr.sin_family = AF_INET; // host byte order     my_addr.sin_port = htons(MYPORT); // short, network byte order     my_addr.sin_addr.s_addr = INADDR_ANY; // automatically fill with my IP     memset(my_addr.sin_zero, '/0', sizeof my_addr.sin_zero);     if (bind(sockfd, (struct sockaddr *)&my_addr, sizeof my_addr) == -1) {         perror("bind");         exit(1);     }     if (listen(sockfd, BACKLOG) == -1) {         perror("listen");         exit(1);     }     sa.sa_handler = sigchld_handler; // reap all dead processes     sigemptyset(&sa.sa_mask);     sa.sa_flags = SA_RESTART;     if (sigaction(SIGCHLD, &sa, NULL) == -1) {         perror("sigaction");         exit(1);     }     while(1) { // main accept() loop         sin_size = sizeof their_addr;         if ((new_fd = accept(sockfd, (struct sockaddr *)&their_addr, &sin_size)) == -1) {             perror("accept");             continue;         }         printf("server: got connection from %s/n",              inet_ntoa(their_addr.sin_addr));         if (!fork()) { // this is the child process             close(sockfd); // child doesn't need the listener             if (send(new_fd, "Hello,Liceven!/n", 14, 0) == -1)                 perror("send");             close(new_fd);             exit(0);         }         close(new_fd); // parent doesn't need this     }     return 0; }

 

#####################client.c######################

 

#include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <errno.h> #include <string.h> #include <netdb.h> #include <sys/types.h> #include <netinet/in.h> #include <sys/socket.h> #define PORT 3424 // the port client will be connecting to #define MAXDATASIZE 100 // max number of bytes we can get at once int main(int argc, char *argv[]) {     int sockfd, numbytes;     char buf[MAXDATASIZE];     struct hostent *he;     struct sockaddr_in their_addr; // connector'saddress information     if (argc != 2) {         fprintf(stderr,"usage: client hostname/n");         exit(1);     }     if ((he=gethostbyname(argv[1])) == NULL) { // get the host info         herror("gethostbyname");         exit(1);     }     if ((sockfd = socket(PF_INET, SOCK_STREAM, 0)) == -1) {         perror("socket");         exit(1);     }     their_addr.sin_family = AF_INET; // host byte order     their_addr.sin_port = htons(PORT); // short, network byte order     their_addr.sin_addr = *((struct in_addr *)he->h_addr);     memset(their_addr.sin_zero, '/0', sizeof their_addr.sin_zero);     if (connect(sockfd, (struct sockaddr *)&their_addr,                                           sizeof their_addr) == -1) {         perror("connect");         exit(1);     }     if ((numbytes=recv(sockfd, buf, MAXDATASIZE-1, 0)) == -1) {         perror("recv");         exit(1);     }     buf[numbytes] = '/0';     printf("Received: %s",buf);     close(sockfd);     return 0; }

 

linux执行：

$gcc -o server server.c

$./server

$gcc -o client client.c

$./client localhost 或者 $./client 127.0.0.1

你可以看到执行结果：

server端：server: got connection from 127.0.0.1

client端：Received: Hello,Liceven!