服务器端代码实现
#include<stdio.h>
#include<strings.h>
#include<string.h>
#include<unistd.h>
#include<sys/types.h>
#include<sys/socket.h>
#include<netinet/in.h>
#include<arpa/inet.h>
#include<sys/time.h>
#include<stdlib.h>
#define PORT 1234
#define BACKLOG 5
#define MAXDATASIZE 1000
typedef struct CLIENT{
int fd;
char* name;
struct sockaddr_in addr; /*client's address information*/
char* data;
}CLIENT;
void process_cli(CLIENT *client,char* recvbuf,int len);/*process client's information*/
void savedata(char* recvbuf,int len,char* data);
int main()
{
int i,maxi,maxfd,sockfd;
int nready;/**/
ssize_t n;
fd_set rset,allset;
int listenfd,connectfd;
struct sockaddr_in server;
CLIENT client[FD_SETSIZE];
char recvbuf[MAXDATASIZE];
int sin_size;
/*creat a TCP socket*/
if((listenfd=socket(AF_INET,SOCK_STREAM,0))==-1)
{
perror("Creating socket failed.");
exit(1);
}
int opt=SO_REUSEADDR;
setsockopt(listenfd,SOL_SOCKET,SO_REUSEADDR,&opt,sizeof(opt));
bzero(&server,sizeof(server));
server.sin_family==AF_INET;
server.sin_port=htons(PORT);
server.sin_addr.s_addr=htonl(INADDR_ANY);
if(bind(listenfd,(struct sockaddr *)&server,sizeof(struct sockaddr))==-1)
{
perror("Bind error.");
exit(1);
}
if(listen(listenfd,BACKLOG)==-1){
perror("listen() error\n");
exit(1);
}
sin_size=sizeof(struct sockaddr_in);
maxfd=listenfd;
maxi=-1;
for(i=0;i<FD_SETSIZE;i++)
{
client[i].fd=-1;/*put the description =-1*/
}
FD_ZERO(&allset);/*empty*/
FD_SET(listenfd,&allset);/*put the listenfd into the description collection*/
while(1)
{
struct sockaddr_in addr;
rset=allset;
nready=select(maxfd+1,&rset,NULL,NULL,NULL);/*call select()*/
if(FD_ISSET(listenfd,&rset))
{
/*new client connection*/ /*accept connection*/
if((connectfd=accept(listenfd,(struct sockaddr *)&addr,&sin_size))==-1)
{
perror("accept() error\n");
continue;
}
/*put new fd to client*/
for(i=0;i<FD_SETSIZE;i++)
if(client[i].fd<0){
client[i].fd=connectfd;
client[i].name=(char*)malloc(sizeof(MAXDATASIZE));
client[i].addr=addr;
client[i].data=(char*)malloc(sizeof(MAXDATASIZE));;
client[i].name[0]='\0';
client[i].data[0]='\0';
printf("You got a connection from %s.",inet_ntoa(client[i].addr.sin_addr));
break;
}
if(i==FD_SETSIZE)/*max description size*/
printf("too many clients\n");
FD_SET(connectfd,&allset);/*put the connectfd into the description collection*/
if(connectfd>maxfd)
maxfd=connectfd;
if(i>maxi)
maxi=i;
if(--nready<=0)/*no more readable descriptiors*/
continue;
}
for(i=0;i<=maxi;i++){/*check all clients for data*/
if((sockfd=client[i].fd)<0)
continue;
if(FD_ISSET(sockfd,&rset)){
if((n=recv(sockfd,recvbuf,MAXDATASIZE,0))==0)
{/*connection closed by client*/
close(sockfd);
printf("Client(%s) closed connection.User's data:%s\n",client[i].name,client[i].data);
FD_CLR(sockfd,&allset);/*delete*/
client[i].fd=-1;
free(client[i].name);
free(client[i].data);
}else
process_cli(&client[i],recvbuf,n);
if(--nready<=0)/*no more readable descriptiors*/
break;
}
}
}
close(listenfd);/*close listenfd*/
}
void process_cli(CLIENT *client,char* recvbuf,int len)
{
char sendbuf[MAXDATASIZE];
recvbuf[len-1]='\0';
if(strlen(client->name)==0){
memcpy(client->name,recvbuf,len);/*copy and display*/
printf("\nClient's name is %s.\n",client->name);
return;
}
/*recvieve client's data*/
printf("Received client(%s) message: %s.\n",client->name,recvbuf);
savedata(recvbuf,len,client->data);
/*achieve reverse*/
for(int il=0;il<len-1;il++){
sendbuf[il]=recvbuf[len-il-2];
}
/*achieve jiami*/
for(int i=0;i<len;i++)
{
if((sendbuf[i]>='a'&&sendbuf[i]<='z')||(sendbuf[i]>='A'&&sendbuf[i]<='Z'))
{
sendbuf[i]=sendbuf[i]+4;
if((sendbuf[i]>'Z'&&sendbuf[i]<='Z'+4)||(sendbuf[i]>'z'))
sendbuf[i]=sendbuf[i]-26;
}
}
sendbuf[len-1]='\0';
send(client->fd,sendbuf,strlen(sendbuf),0);
printf("Reversed and encrypted client(%s) message:%s\n",client->name,sendbuf);
}
void savedata(char* recvbuf,int len,char* data)
{
int start = strlen(data);
for(int i=0;i<len;i++){
data[start+i]=recvbuf[i];
}
}
客户端代码实现
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#define PORT 1234
#define MAXDATASIZE 100
void process(FILE *fp,int sockfd);
char* getMessage(char* sendline,int len,FILE* fp);
int main(int argc,char *argv[]){
int sockfd;
struct hostent *he;
struct sockaddr_in server;
if (argc!=2){
printf("Usage:%s<IP Address>\n",argv[0]);
exit(1);
}
if((he=gethostbyname(argv[1]))==NULL){
printf("gethostbyname() error\n");
exit(1);
}
if((sockfd=socket(AF_INET,SOCK_STREAM,0))==-1){
printf("socket() error\n");
exit(1);
}
bzero(&server,sizeof(server));
server.sin_family=AF_INET;
server.sin_port=htons(PORT);
server.sin_addr=*((struct in_addr *)he->h_addr);
if(connect(sockfd,(struct sockaddr *)&server,sizeof(server))==-1){
printf("connect() error\n");
exit(1);
}
process(stdin,sockfd);
close(sockfd);
}
void process(FILE *fp,int sockfd){
char sendline[MAXDATASIZE],recvline[MAXDATASIZE];
int num;
printf("Connected to server.\n");
printf("Input client's name:");
if(fgets(sendline,MAXDATASIZE,fp)==NULL){
printf("\nExit.\n");
return;
}
send(sockfd,sendline,strlen(sendline),0);
while(getMessage(sendline,MAXDATASIZE,fp)!=NULL){
send(sockfd,sendline,strlen(sendline),0);
if((num=recv(sockfd,recvline,MAXDATASIZE,0))==0){
printf("Server terminated.\n");
return;
}
recvline[num]='\0';
printf("Server Message:%s\n",recvline);
}
printf("\nExit.\n");
}
char* getMessage(char* sendline,int len,FILE* fp){
printf("Input string to server:");
return(fgets(sendline,MAXDATASIZE,fp));
}
运行示例
