//
//  CS461 Distributed Computing and Networking
//  Princeton University
//  Tammo Spalink, Andy Bavier
// 
//  Spring 2002, Revision 1
//

#include <stdio.h>
#include <stdlib.h>

#include "interface.h"

#include <sys/types.h>
#include <linux/ip.h>
#include <arpa/inet.h>
#include <sys/uio.h>

#define FOREVER ;;

// A simple clock callback 
void
clockHandler(void)
{
    fprintf(stderr, "!");
}

// A simple IO callback to reflect "pings".  You'll actually see two dots
// printed for every ping; the ECHO_REQUEST message is echoed back to the 
// sender, who then replies to it. In other words, 
//   src -> ECHO_REQUEST -> dst
//   src <- ECHO_REQUEST <- dst
//   src -> ECHO_REPLY   -> dst
//   src <- ECHO_REPLY   <- dst
void
recvHandler(void *buf)
{
    struct iphdr *header;
    unsigned int tmp;
    struct iovec iov;

    header = (struct iphdr *)buf;
    tmp = header->daddr;

    /* Swap the source and destination addresses */
    header->daddr = header->saddr;
    header->saddr = tmp;

    iov.iov_base = buf;
    iov.iov_len = ntohs(header->tot_len);

    /* Send the packet to the router, let it figure out where it goes next */
    CS461_SendIov(inet_addr("128.112.4.6"), &iov, 1);

    /* We are done with packet processing */
    CS461_Free(buf);

    fprintf(stderr, ".");
}

// The main() function just initializes the callbacks and then loops
// until the program is shut down. 
int
main(void)
{
    CS461_Initialize(IPPROTO_ICMP, recvHandler, clockHandler, 1000, 0);

    CS461_InterruptToggle(CS461_INTON);

    for (FOREVER) {
        CS461_Block();
    }
    
    return 0;
}