linux c server and client 简单的通信

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[1000]="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);

        }

        /* 服务器端开始建立socket描述符 */

        if((sockfd=socket(AF_INET,SOCK_STREAM,0))==-1)

        {

                fprintf(stderr,"Socket error:%s\n\a",strerror(errno));

                exit(1);

        }

        /* 服务器端填充 sockaddr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);

        /* 捆绑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);

        }

        /* 监听sockfd描述符  */

        if(listen(sockfd,5)==-1)

        {

                fprintf(stderr,"Listen error:%s\n\a",strerror(errno));

                exit(1);

        }

        while(1)

        {

                /* 服务器阻塞,直到客户程序建立连接  */

                sin_size=sizeof(struct sockaddr_in);

                if((new_fd=accept(sockfd,(struct sockaddr *)(&client_addr),&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));

                fscanf(stdin,"%s",hello);

                if(write(new_fd,hello,strlen(hello))==-1)

                {

                        fprintf(stderr,"Write Error:%s\n",strerror(errno));

                        exit(1);

                }

                /* 这个通讯已经结束     */

                close(new_fd);

                /* 循环下一个     */

        }

        close(sockfd);

        exit(0);

}

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(argc!=3)

        {

                fprintf(stderr,"Usage:%s hostname portnumber\a\n",argv[0]);

                exit(1);

        }

        if((host=gethostbyname(argv[1]))==NULL)

        {

                fprintf(stderr,"Gethostname error\n");

                exit(1);

        }

        if((portnumber=atoi(argv[2]))<0)

        {

                fprintf(stderr,"Usage:%s hostname portnumber\a\n",argv[0]);

                exit(1);

        }

        /* 客户程序开始建立 sockfd描述符  */

        if((sockfd=socket(AF_INET,SOCK_STREAM,0))==-1)

        {

                fprintf(stderr,"Socket Error:%s\a\n",strerror(errno));

                exit(1);

        }

        /* 客户程序填充服务端的资料       */

        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);

        /* 客户程序发起连接请求         */

        if(connect(sockfd,(struct sockaddr *)(&server_addr),sizeof(struct sockaddr))==-1)

        {

                fprintf(stderr,"Connect Error:%s\a\n",strerror(errno));

                exit(1);

        }

        /* 连接成功了           */

        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);

        /* 结束通讯     */

        close(sockfd);

        exit(0);

}

Makefile

all:server client

server:server.c

            gcc $^ -o $@

client:client.c

            gcc $^ -o $@