int isPallindrome(Node **root ,int size){
if(size<=1){
return 1;
}
Node *start_ptr ,*end_ptr;
end_ptr = start_ptr = *(root);
int i=1;
while(i<size){
end_ptr = end_ptr->next;
i++;
}
if(end_ptr->val != start_ptr->val){
return 0;
}
return isPallindrome(&(start_ptr->next),size-2);
}
//MAIN FUNCTION
void main()
{
/*DECLARATION OF VARIABLES*/
int tcpSocket,udpSocket,newtcpSocket ;
struct sockaddr_in serv_addr,clientAddr;
struct sockaddr_storage serverStorage;
socklen_t addr_size;
fd_set readfds;
struct timeval tv;
int i,rv,nBytes,clilen,n,flag,len;
char buf1[100], buf2[100];
/*TCP SOCKET*/
//CREATING TCP SOCKET
if ((tcpSocket = socket(PF_INET, SOCK_STREAM, 0)) < 0)
{
printf("Unable to create socket\n");
exit(0);
}
//INTIALISING THE SOCKET VARIABLES
serv_addr.sin_family= AF_INET;
serv_addr.sin_addr.s_addr=inet_addr("127.0.0.1");
serv_addr.sin_port=htons(50040);
//BINDING THE TCP SOCKET
if (bind(tcpSocket, (struct sockaddr *) &serv_addr,sizeof(serv_addr)) < 0)
{
printf("Unable to bind local address\n");
exit(0);
}
//LISTENING TO 5 CALLS
listen(tcpSocket, 5);
/*UDP SOCKET*/
//CREATING UDP SOCKET
if ((udpSocket = socket(PF_INET, SOCK_DGRAM, 0)) <0)
{
printf("Unable to create socket\n");
exit(0);
}
//INTIALISING THE SOCKET VARIABLES
serv_addr.sin_family = AF_INET;
serv_addr.sin_port = htons(50015);
serv_addr.sin_addr.s_addr = inet_addr("127.0.0.1");
memset(serv_addr.sin_zero, '\0', sizeof serv_addr.sin_zero);
//BINDING THE UDP SOCKET
if (bind(udpSocket, (struct sockaddr *) &serv_addr, sizeof(serv_addr)) < 0)
{
printf("Unable to bind local address\n");
exit(0);
}
addr_size = sizeof serverStorage;
//finding the highest number of socket descriptor
if (tcpSocket > udpSocket)
n = (tcpSocket + 1);
else
n = (udpSocket + 1);
while(1)
{
FD_ZERO(&readfds); //clearing the socket set
FD_SET(tcpSocket, &readfds);//adding TCP socket to the socket set for reading
FD_SET(udpSocket, &readfds);//adding UDP socket to the socket set for reading
rv = select(n, &readfds, NULL, NULL, NULL);
if (rv == -1)
{
perror("select"); // error occurred in select()
}
else if (rv == 0)
{
printf("No data!!");
}
else
{
// one or both of the descriptors have data
if (FD_ISSET(tcpSocket, &readfds))
{
//clearing the buffer
for(i=0;i<100;i++)
buf1[i]='\0';
//accepting the TCP client
clilen = sizeof(clientAddr);
newtcpSocket = accept(tcpSocket, (struct sockaddr *) &clientAddr,&clilen) ;
if (newtcpSocket < 0)
{
printf("Accept error\n");
exit(0);
}
//receiving message from client
read(newtcpSocket, buf1, 100);
len = strlen(buf1);
flag = 1;
printf("Word being received at TCP socket is %s",buf1);
printf("\n################################\n");
//checking word is pallindrome or not
flag = isPallindrome(buf1);
if(flag == 1)
strcpy(buf1,"The word entered by you is a Palindrome");
else
strcpy(buf1,"The word entered by you is not a Palindrome");
//sending the result to client
write(newtcpSocket,buf1,strlen(buf1)+1);
//clearing the buffer for next iteration
for(i=0;i<100;i++)
buf1[i]='\0';
}
if (FD_ISSET(udpSocket, &readfds))
{
//clearing the buffer
for(i=0;i<100;i++)
buf2[i]='\0';
//receiving from UDP client
nBytes = recvfrom(udpSocket,buf2,100,0,(struct sockaddr *)&serverStorage, &addr_size);
len = strlen(buf2);
printf("Word being received at UDP socket is %s",buf2);
printf("\n#######################################\n");
flag = 1;
//checking word is pallindrome or not
flag = isPallindrome(buf2);
if(flag == 1)
strcpy(buf2,"The word entered by you is a Palindrome");
else
strcpy(buf2,"The word entered by you is not a Palindrome");
//sending result back to client
sendto(udpSocket,buf2,strlen(buf2)+1,0,(struct sockaddr *)&serverStorage,addr_size);
//clearing the buffer for next iteration
for(i=0;i<100;i++)
buf2[i]='\0';
}
}
}
}
