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#include <u.h>
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#include <libc.h>
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#include <ip.h>
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#include "../icmp.h"
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static void
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catch(void *a, char *msg)
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{
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	USED(a);
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	if(strstr(msg, "alarm"))
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		noted(NCONT);
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	else
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		noted(NDFLT);
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}
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#define MSG "dhcp probe"
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/*
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 *  make sure noone is using the address
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 *  TODO: ipv6 ping
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 */
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int
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icmpecho(uchar *a)
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{
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	int fd, i, n, len, rv;
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	ushort sseq, x;
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	char buf[512];
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	Icmphdr *ip;
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	rv = 0;
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	if (!isv4(a))
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		return 0;
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	sprint(buf, "%I", a);
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	fd = dial(netmkaddr(buf, "icmp", "1"), 0, 0, 0);
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	if(fd < 0){
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		return 0;
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	}
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	sseq = getpid()*time(0);
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	ip = (Icmphdr *)(buf + IPV4HDR_LEN);
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	notify(catch);
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	for(i = 0; i < 3; i++){
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		ip->type = EchoRequest;
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		ip->code = 0;
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		strcpy((char*)ip->data, MSG);
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		ip->seq[0] = sseq;
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		ip->seq[1] = sseq>>8;
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		len = IPV4HDR_LEN + ICMP_HDRSIZE + sizeof(MSG);
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		/* send a request */
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		if(write(fd, buf, len) < len)
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			break;
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		/* wait 1/10th second for a reply and try again */
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		alarm(100);
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		n = read(fd, buf, sizeof(buf));
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		alarm(0);
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		if(n <= 0)
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			continue;
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		/* an answer to our echo request? */
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		x = (ip->seq[1]<<8) | ip->seq[0];
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		if(n >= len && ip->type == EchoReply && x == sseq &&
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		    strcmp((char*)ip->data, MSG) == 0){
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			rv = 1;
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			break;
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		}
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	}
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	close(fd);
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	return rv;
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}