리눅스 채팅프로그램 좀 봐주세요

리눅스에서 채팅프로그램을 만들었는데....실행하니깐..서로 메세지교환이 안되고 접속이 그냥 끊겨버려여...
어디가 잘못된것인지...답변부탁드립니다.

================chat_server.c=====================

#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <signal.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <fcntl.h>

#define maxline 1024
char *escapechar="exit\n";

int main(int argc,char *argv[])
{
        int s,client_fd,clilen;
        int num=0,i,j,n;
        int nfds;
        char sendline[maxline],rline[maxline],*buf;
        int client_s[512];
        fd_set read_fds;//읽기감지구조체
        struct sockaddr_in client_addr,server_addr;

        if(argc<2)
        {

                printf("usage :%s tcp_port\n",argv[0]);
                return -1;
        }
        //소켓생성
        if((s=socket(PF_INET,SOCK_STREAM,0))<0)
        {
                perror("server:can't open stream socket\n");
                return -1;
        }

        bzero((char *)&server_addr,sizeof(server_addr));
        server_addr.sin_family=AF_INET;
        server_addr.sin_addr.s_addr=htonl(INADDR_ANY);
        server_addr.sin_port=htons(atoi(argv[1]));

        if(bind(s,(struct sockaddr *)&server_addr,sizeof(server_addr))<0)
        {
                printf("server:can't locla address\n");
                return -1;
        }

//client로부터 연결기다림
        listen(s,5);
        FD_ZERO(&read_fds);//초기화
        nfds=s+1;
        while(1)
        {
                //(s-1)값갱신
                if((num-1)>=0)
                        nfds=client_s[num-1]+1;

                FD_SET(s,&read_fds); //초기소켓선택
                for(i=0;i<num;i++)
                        FD_SET(client_s[i],&read_fds);

                if(select(nfds,&read_fds,0,0,0)<0)
                {
                        printf("select error\n");
                        return -1;
                }
                if(FD_ISSET(s,&read_fds))
                {
                        //초기소켓 s에서 입력발생
                        clilen=sizeof(client_addr);
                        client_fd=accept(s,(struct sockaddr *)&client_addr,&clilen);
                        if(client_fd !=-1)
                        {
                                client_s[num]=client_fd;
                                num++;
                                send(client_fd,buf,strlen(buf),0);
                        }
                }
                //client에 메세지도착검색
                //client소켓버호 배열 client[]를 검색
                for(i=0;i<num;i++)
                {
                        if(FD_ISSET(client_s[i],&read_fds))
                        {
                                if((n=recv(client_s[i],rline,maxline,0))>0)
                                {
                                        rline[n]='\0';
                                        //종료문자입력시 탈퇴
                                        if(strncmp(rline,escapechar,5)==1)
                                        {
                                                shutdown(client_s[i],2);
                                                if(i !=num-1)
                                                        client_s[i]=client_s[num-1];
                                                num--;
                                                continue;
                                        }
                                        //모든 client에 메세지전송
                                        for(j=0;j<num;j++)
                                                send(client_s[j],rline,n,0);

                                       printf("%s",rline);
                                }
                        }
                }
        }
}

===========chat_client.c========================

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <fcntl.h>
#include <sys/time.h>

#define maxline 1024

char *escapechar="exit\n";
int readline(int fd,char *ptr , int maxlen)
{
        int n,r;
        char c;
        for(n=1;n<maxlen;n++)
        {
                if((r=read(fd,&c,1))==1)
                {
                        *ptr++=c;
                        if(c=='\n');
                        break;
                }
                else if(r==0)
                {
                        if(n==1)
                                return(0);
                        else
                                break;
                }
        }
        *ptr=0;
        return(n);
}

int main(int argc,char *argv[])
{
        char line[maxline],sendline[maxline+1];
        int s,n,pid,size;
        int nfds;
        struct sockaddr_in server_addr;

        fd_set read_fds; //구조체
        if(argc <3)
        {
                printf("usage: %s server_address tcp_port\n",argv[0]);
                return -1;
        }
        //소켓생성
        if((s=socket(PF_INET,SOCK_STREAM,0))<0)
        {
                printf("client:can't open stream socket\n");
                return -1;
        }
        //소켓주소 구조체
        bzero((char *)&server_addr,sizeof(server_addr));
        server_addr.sin_family=AF_INET;
        server_addr.sin_addr.s_addr=inet_addr(argv[1]);
        server_addr.sin_port=htons(atoi(argv[2]));
        //연결
        if(connect(s,(struct sockaddr *)&server_addr,sizeof(server_addr))<0)
        {
                printf("clinet: can't connect to server\n");
                return -1;
        }
        nfds=s+1;
        FD_ZERO(&read_fds); //초기화
        //select호출
        while(1)
        {
                FD_SET(0,&read_fds);
                FD_SET(s,&read_fds);
                if(select(nfds,&read_fds,NULL,NULL,NULL)<0)
                {
                        printf("select error\n");
                        return -1;
                }

                //서버가 보내오는 메세지출력
                if(FD_ISSET(s,&read_fds))
                {
                        char recvline[maxline];

                        if((size=recv(s,recvline,maxline,0))>0)
                        {
                                recvline[size]='\0';
                                printf("%s\n",recvline);
                        }
                }
                //입력데이타를 서버로전송
                if(FD_ISSET(0,&read_fds))
                {
                        if(readline(0,sendline,maxline)>0)
                        {
                                size=strlen(sendline);
                                sprintf(line,"%s",sendline);
                                if(send(s,line,size,0) !=(size))
                                {
                                        printf("error:written error..\n");
                                }
                                if(size==5 && strncmp(sendline,escapechar,5)==0)
                                {
                                        close(s);
                                        return -1;
                                }
                        }
                }
        }
}