Linux work

#include <stdio.h>          
#include <strings.h>         
#include <unistd.h>         
#include <sys/types.h> 
#include <sys/socket.h> 
#include <netinet/in.h> 
#include <arpa/inet.h>

#define PORT 1234   
#define BACKLOG 5   
#define MAXDATASIZE 1000  
void process_cli(int connfd, struct sockaddr_in client);

main() 
{ 
	int listenfd, connfd; 
	pid_t pid;
	struct sockaddr_in server; 
	struct sockaddr_in client; 
	int len; 	
	int opt = SO_REUSEADDR;
	if ((listenfd = socket(AF_INET, SOCK_STREAM, 0)) == -1) 
	{
	   	perror("socket");
	   	exit(1);
	}
	
	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(server)) == -1) 
	{ 
	   	perror("bind");
	   	exit(1); 
	}    

	if(listen(listenfd,BACKLOG) == -1)
	{  
	   perror("listen"); 
	   exit(1); 
	}

	len=sizeof(client); 
	while(1)
	{
		 if ((connfd = accept(listenfd,(struct sockaddr *)&client,&len))==-1) 
		 {
		   	perror("accept"); 
		   	exit(1); 
		 } 
		if ((pid=fork())>0) 
		{
		   	close(connfd);
		   	continue;
		}
		else if (pid==0) 
		{
		   	close(listenfd);
		   	process_cli(connfd, client);
		   	exit(0);     
		}
		else 
		{
		   	perror("fork");
		   	exit(0);
		}
	}
	close(listenfd);   
} 

void exchange(char *src,int num)
{
	char c;
	int i;
	src[num-1]=0;
	num=num-1;
	printf("%d\n",num);
	for(i=0;i<num;i++)
	{
		
		c=src[i];
		src[i]=src[num-1];
		src[num-1]=c;
		num=num-1;
		if(num<=i)
			break;
	}
}

void process_cli(int connfd, struct sockaddr_in client)
{
	int num;
	char exitflag=0;
	char recvbuf[MAXDATASIZE], sendbuf[MAXDATASIZE], cli_name[MAXDATASIZE];
	printf("got a connection from %s.\n",inet_ntoa(client.sin_addr) );
	num = recv(connfd, cli_name, MAXDATASIZE,0);
	if (num == -1) 
	{
	   	close(connfd);
	   	perror("recv");
	   	return;
	}
	cli_name[num - 1] = '\0';
	printf("%s client's name is %s.\n",inet_ntoa(client.sin_addr),cli_name);	
	while (num = recv(connfd, recvbuf, MAXDATASIZE,0)) 
	{
	   recvbuf[num] = '\0';
	   printf("%s:%s",cli_name, recvbuf);
	   if(strcmp(recvbuf,"bye")==0)
		exitflag=1;
	   exchange(recvbuf,num);
	   send(connfd,recvbuf,num,0); 
	   if(exitflag==1)
		break;
	}
	close(connfd);
	printf("client %s from %s  end.\n",cli_name,inet_ntoa(client.sin_addr));
}

#include <stdio.h> 
#include <unistd.h>
#include <strings.h>
#include <sys/types.h> 
#include <sys/socket.h> 
#include <netinet/in.h> 
#include <netdb.h>       
#include <time.h>       
#include <fcntl.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)
	{  
	   	perror("socket"); 
	   	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)
	{ 
	   perror("connect"); 
	   exit(1); 
	} 	
	process(stdin,sockfd);	
	close(sockfd);     
}


void writefile(int fd,char *str) 
{
	time_t t1;
	struct tm *t2;
	char wtext[100];
	t1=time(NULL);
	t2=localtime(&t1);
	sprintf(wtext,"%d-%d-%d-%d:%d:%d",t2->tm_year+1900,t2->tm_mon+1,t2->tm_mday,t2->tm_hour,t2->tm_min,t2->tm_sec);
	sprintf(wtext,"%s	%s\n",wtext,str);
	write(fd,wtext,strlen(wtext));
}
	
void process(FILE *fp, int sockfd)
{
	char	sendline[MAXDATASIZE], recvline[MAXDATASIZE];
	int num;
	int fd;
	time_t  t1;
	struct tm *t2;
	char cname[30];
	char tmp[100];
	printf("Connected to server. \n");
	printf("Input client's name : ");
	if ( fgets(cname, 30, fp) == NULL) 
	{
	  	printf("\nExit.\n");
	  	return;
	}
	send(sockfd, cname, strlen(cname),0);	
	cname[strlen(cname)-1]=0;
	fd=open(cname,O_WRONLY|O_CREAT|O_APPEND,0644);
	if(fd==-1)
	{
		perror("open");
	}
	writefile(fd,"connection success");
	while (getMessage(sendline, MAXDATASIZE, fp) != NULL) 
	{
	   	send(sockfd, sendline, strlen(sendline),0);	   	
		sendline[strlen(sendline)-1]=0;
		sprintf(tmp,"%s	:	%s",cname,sendline);
		writefile(fd,tmp);
	   	if ((num = recv(sockfd, recvline, MAXDATASIZE,0)) == 0) 
	   	{
	   	   	printf("Server terminated.\n");
	   	   	return;
	   	}	   	
	   	recvline[num]='\0'; 
	   	printf("Server Message: %s\n",recvline); 
		sprintf(tmp,"server	:	%s",recvline);
		writefile(fd,tmp);
		if(strcmp(sendline,"bye")==0)
			break;
	}
	printf("\nExit.\n");
	writefile(fd,"close connection");
} 

char* getMessage(char* sendline,int len, FILE* fp) 
{
	printf("Input string to server:");
	return(fgets(sendline, MAXDATASIZE, fp));
}

SP=server
C=client

all:$(SP) $(C) 

$(SP):$(SP).c
	gcc $^  -o  $@
$(C):$(C).c
	gcc $^  -o  $@

clean:
	rm -f $(SP)  $(C)