TCP Iterative Client / Server Program to echo the text in reverse

/*
TCP iterative SERVER program
The following program shows the contents of Filename : TCP_it_ser.c.
*/
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/wait.h>
#include <fcntl.h>
#include <unistd.h>

#define MYPORT 13153 /*The port users will be connecting to*/
void readstring(int,char *);
int main(int C, char *V[] )
{
int listensocket,connectionsocket,retbind;
struct sockaddr_in
serveraddress,cliaddr;
socklen_t len;
char buf[100],databuf[1024];
listensocket = socket(AF_INET, SOCK_STREAM, 0 );
if (listensocket < 0 )
{
perror("socket" );
exit(1);
}
memset(&serveraddress, 0, sizeof(serveraddress) );
serveraddress.sin_family = AF_INET;
serveraddress.sin_port = htons(MYPORT);/*PORT NO*/
serveraddress.sin_addr.s_addr =
htonl(INADDR_ANY);/*ADDRESS*/
retbind=bind(listensocket,(struct sockaddr*)&serveraddress,
sizeof(serveraddress));
/*Check the return value of bind for error*/
if(-1==retbind)
{
perror("BIND ERROR\n");
exit(1);
}
listen(listensocket,5);
/*Beginning of the Main Server Processing Loop*/
for (;;)
{
printf("Server:I am waiting-----Start of Main Loop\n");
len=sizeof(cliaddr);
connectionsocket=accept(listensocket,
(struct sockaddr*)&cliaddr,&len);
if (connectionsocket < 0)
{
if (errno == EINTR)
printf("Interrupted system call ??");
continue;
}
printf("Connection from %s\n",
inet_ntop(AF_INET,&cliaddr.sin_addr,buf,sizeof(buf)));
readstring(connectionsocket , databuf);
close(connectionsocket);
printf("Finished Serving One Client\n");
}
}

/***********************************************************
* FUNCTION NAME:readstring
* DESCRIPTION: Reads the string sent by the client over the
* socket and stores it in the array fname .
* NOTES : No Error Checking is done .
* RETURNS :void
***********************************************************/

void readstring(int connectionsocket,char *fname) /*Array , to be populated by the string from client*/
{
int pointer=0,n;
int len=0,a,b;
char rev[50],temp[50],temp1[50];
int k,i;
while ((n=read(connectionsocket,(fname + pointer),1024))>0)
{
pointer=pointer+n;
}
fname[pointer]='\0';
printf("enter the string\n");
printf("Server :Received %s\n " ,fname);
//strcpy(temp,fname);
k=strlen(fname);
// for(k=0;temp[k]!=0;k++);
// len=k;
a=0;
for(i=k-1;i>=0;i--)
temp[a++]=fname[i];
temp[a]='\0';
printf("\nrev is %s\n", temp);
}

/*
TCP ITERATIVE CLIENT program
The following program shows the contents of Filename : TCP_it_clnt.c.
*/

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <fcntl.h>
#define MAXBUFFER 1024
void sendstring(int , char *);

int main( int C, char *V[] )
{
int sd,fd;
char c;
struct sockaddr_in serveraddress;
char text[100];
int i=0;
sd = socket( AF_INET, SOCK_STREAM, 0 );
if( sd < 0 ) {
perror( "socket" );
exit( 1 );
}
if (V[1] == NULL ) {
printf ("PL specfiy the server's IP Address \n");
exit(0);
}
if (V[2] == NULL ) {
printf ("PL specify the server's Port No \n");
exit(0);
}
memset( &serveraddress, 0, sizeof(serveraddress) );
serveraddress.sin_family = AF_INET;
serveraddress.sin_port = htons(atoi(V[2]));//PORT NO
serveraddress.sin_addr.s_addr = inet_addr(V[1]);//ADDRESS
if (connect(sd,(struct sockaddr*)&serveraddress,
sizeof(serveraddress))<0)
{
printf("Cannot Connect to server");
exit(1);
}
printf("enter sentence to end enter #");
while(1)
{
c=getchar();
if(c=='#')
break;
text[i++]=c;
}
text[i]='\0';
sendstring(sd,text);
close(sd);
return 0;
}
/**********************************************************
* FUNCTION NAME:sendstring
* DESCRIPTION: sends a string over the socket .
* NOTES : No Error Checking is done .
* RETURNS :void
***********************************************************/
void sendstring(
int sd, /*Socket Descriptor*/
char *fname) /*Array Containing the string */
/**********************************************************/
{ int n , byteswritten=0 , written ;
char buffer[MAXBUFFER];
strcpy(buffer , fname);
n=strlen(buffer);
while (byteswritten<n)
{
written=write(sd , buffer+byteswritten,(n-byteswritten));
byteswritten+=written;
}
printf("String : %s sent to server \n",buffer);
}
/***********************************************************/




/*

Execution & results:
1. Compiling and running server.

[user@localhost rvs]$ cc tcpserver.c
[user@localhost rvs]$ mv a.out tcpserver
[user@localhost rvs]$ ./tcpserver
Server:I am waiting-----Start of Main Loop
Connection from 127.0.0.1
enter the string
Server :Received Network Programming
Rev string is gnimmargorP krowteN
Finished Serving One Client
Server:I am waiting-----Start of Main Loop
2. Compiling and running client.

[user@localhost rvs]$ cc tcpclient.c
[user@localhost rvs]$ mv a.out tcpclient
[user@localhost rvs]$./tcpclient 127.0.0.1 13153
enter sentence to end enter #Network Programming#
String : Network Programming sent to server

*/