Subversion Repositories planix.SVN

#include <u.h>
#include <libc.h>
#include <ip.h>
#include "../icmp.h"

static void
catch(void *a, char *msg)
{
        USED(a);
        if(strstr(msg, "alarm"))
                noted(NCONT);
        else
                noted(NDFLT);
}

#define MSG "dhcp probe"

/*
 *  make sure noone is using the address
 *  TODO: ipv6 ping
 */
int
icmpecho(uchar *a)
{
        int fd, i, n, len, rv;
        ushort sseq, x;
        char buf[512];
        Icmphdr *ip;

        rv = 0;
        if (!isv4(a))
                return 0;
        sprint(buf, "%I", a);
        fd = dial(netmkaddr(buf, "icmp", "1"), 0, 0, 0);
        if(fd < 0){
                return 0;
        }

        sseq = getpid()*time(0);

        ip = (Icmphdr *)(buf + IPV4HDR_LEN);
        notify(catch);
        for(i = 0; i < 3; i++){
                ip->type = EchoRequest;
                ip->code = 0;
                strcpy((char*)ip->data, MSG);
                ip->seq[0] = sseq;
                ip->seq[1] = sseq>>8;
                len = IPV4HDR_LEN + ICMP_HDRSIZE + sizeof(MSG);

                /* send a request */
                if(write(fd, buf, len) < len)
                        break;

                /* wait 1/10th second for a reply and try again */
                alarm(100);
                n = read(fd, buf, sizeof(buf));
                alarm(0);
                if(n <= 0)
                        continue;

                /* an answer to our echo request? */
                x = (ip->seq[1]<<8) | ip->seq[0];
                if(n >= len && ip->type == EchoReply && x == sseq &&
                    strcmp((char*)ip->data, MSG) == 0){
                        rv = 1;
                        break;
                }
        }
        close(fd);
        return rv;
}