TCP concurrent client/server program to echo a string in reverse

/* TCP concurrent server program to echo the string in reverse file : tcp_echo_ser.c */
#include "unp.h"
# include <string.h>
void
str_echo(int sockfd)
{
long arg1, arg2;
ssize_t n;
char line[MAXLINE];
char c,*s;
int i,j;
for ( ; ; ) {
if ( (n = Readline(sockfd, line, MAXLINE)) == 0)
return; /* connection closed by other end */

n = strlen(line);

s=line;
printf("\nReq From Client : %s",line);
for(i=0,j=n-1;i<n/2;i++,j--)
{
c=s[i];
s[i]=s[j];
s[j]=c;
}



Writen(sockfd, line, n);
}
}

int
main(int argc, char **argv)
{
int listenfd, connfd;
pid_t childpid;
socklen_t clilen;
struct sockaddr_in cliaddr, servaddr;

listenfd = Socket(AF_INET, SOCK_STREAM, 0);

bzero(&servaddr, sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
servaddr.sin_port = htons(SERV_PORT);

Bind(listenfd, (SA *) &servaddr, sizeof(servaddr));

Listen(listenfd, LISTENQ);

printf("Server Running on Port %d\n", SERV_PORT);
for ( ; ; ) {
clilen = sizeof(cliaddr);
connfd = Accept(listenfd, (SA *) &cliaddr, &clilen);

if ( (childpid = Fork()) == 0) { /* child process */
Close(listenfd); /* close listening socket */
str_echo(connfd); /* process the request */
exit(0);
}
Close(connfd); /* parent closes connected socket */
}
}

/*###########################################################################*/

  /* TCP concurrent client  program to echo the string in reverse file : tcp_echo_clnt.c */
#include "unp.h"
# include <string.h>
void
str_echo(int sockfd)
{
long arg1, arg2;
ssize_t n;
char line[MAXLINE];
char c,*s;
int i,j;
for ( ; ; ) {
if ( (n = Readline(sockfd, line, MAXLINE)) == 0)
return; /* connection closed by other end */

n = strlen(line);

s=line;
printf("\nReq From Client : %s",line);
for(i=0,j=n-1;i<n/2;i++,j--)
{
c=s[i];
s[i]=s[j];
s[j]=c;
}



Writen(sockfd, line, n);
}
}

int
main(int argc, char **argv)
{
int listenfd, connfd;
pid_t childpid;
socklen_t clilen;
struct sockaddr_in cliaddr, servaddr;

listenfd = Socket(AF_INET, SOCK_STREAM, 0);

bzero(&servaddr, sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
servaddr.sin_port = htons(SERV_PORT);

Bind(listenfd, (SA *) &servaddr, sizeof(servaddr));

Listen(listenfd, LISTENQ);

printf("Server Running on Port %d\n", SERV_PORT);
for ( ; ; ) {
clilen = sizeof(cliaddr);
connfd = Accept(listenfd, (SA *) &cliaddr, &clilen);

if ( (childpid = Fork()) == 0) { /* child process */
Close(listenfd); /* close listening socket */
str_echo(connfd); /* process the request */
exit(0);
}
Close(connfd); /* parent closes connected socket */
}
}