linux 下實現伺服器與用戶端串連小例子

// 伺服器端/******* 伺服器程式  (server.c) ************/#include <stdlib.h>#include <stdio.h>#include <errno.h>#include <string.h>#include <unistd.h>#include <netdb.h>#include <sys/socket.h>#include <netinet/in.h>#include <sys/types.h>#include <arpa/inet.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((portnumber=atoi("8080"))<0)        {                fprintf(stderr,"Usage:%s portnumber\a\n",argv[0]);                exit(1);        }        /* 伺服器端開始建立socket描述符 */        if((sockfd=socket(AF_INET,SOCK_STREAM,0))==-1)        {                fprintf(stderr,"Socket error:%s\n\a",strerror(errno));                exit(1);        }        /* 伺服器端填充 sockaddr結構  */        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);        /* 捆綁sockfd描述符  */        if(bind(sockfd,(struct sockaddr *)(&server_addr),sizeof(struct sockaddr))==-1)        {                fprintf(stderr,"Bind error:%s\n\a",strerror(errno));                exit(1);        }        /* 監聽sockfd描述符  */        if(listen(sockfd,5)==-1)        {                fprintf(stderr,"Listen error:%s\n\a",strerror(errno));                exit(1);        }        while(1)        {        fprintf(stderr, "server is listening!\n");                /* 伺服器阻塞,直到客戶程式建立串連  */                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);                }                /* 這個通訊已經結束     */                close(new_fd);                /* 迴圈下一個     */        }        close(sockfd);        exit(0);}

/******* 用戶端程式  client.c ************/#include <stdlib.h>#include <stdio.h>#include <errno.h>#include <string.h>#include <unistd.h>#include <netdb.h>#include <sys/socket.h>#include <netinet/in.h>#include <sys/types.h>#include <arpa/inet.h>int main(int argc, char *argv[]){        int sockfd;        char buffer[1024];        struct sockaddr_in server_addr;        struct hostent *host;        int portnumber,nbytes;        if((host=gethostbyname("10.1.39.93"))==NULL)        {                fprintf(stderr,"Gethostname error\n");                exit(1);        }        if((portnumber=atoi("8080"))<0)        {                fprintf(stderr,"Usage:%s hostname portnumber\a\n",argv[0]);                exit(1);        }        /* 客戶程式開始建立 sockfd描述符  */        if((sockfd=socket(AF_INET,SOCK_STREAM,0))==-1)        {                fprintf(stderr,"Socket Error:%s\a\n",strerror(errno));                exit(1);        }        /* 客戶程式填充服務端的資料       */        bzero(&server_addr,sizeof(server_addr));        server_addr.sin_family=AF_INET;        server_addr.sin_port=htons(portnumber);        server_addr.sin_addr=*((struct in_addr *)host->h_addr);        /* 客戶程式發起串連請求         */        if(connect(sockfd,(struct sockaddr *)(&server_addr),sizeof(struct sockaddr))==-1)        {                fprintf(stderr,"Connect Error:%s\a\n",strerror(errno));                exit(1);        }        /* 串連成功了           */        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);        /* 結束通訊     */        close(sockfd);        exit(0);}