1 87a52e04 2005-12-26 devnull #include <u.h>
  2 87a52e04 2005-12-26 devnull #include <libc.h>
  3 87a52e04 2005-12-26 devnull #include <ip.h>
  4 87a52e04 2005-12-26 devnull 
  5 87a52e04 2005-12-26 devnull 
  6 87a52e04 2005-12-26 devnull typedef struct Icmp Icmp;
  7 87a52e04 2005-12-26 devnull struct Icmp
  8 87a52e04 2005-12-26 devnull {
  9 87a52e04 2005-12-26 devnull 	uchar	vihl;		/* Version and header length */
 10 87a52e04 2005-12-26 devnull 	uchar	tos;		/* Type of service */
 11 87a52e04 2005-12-26 devnull 	uchar	length[2];	/* packet length */
 12 87a52e04 2005-12-26 devnull 	uchar	id[2];		/* Identification */
 13 87a52e04 2005-12-26 devnull 	uchar	frag[2];	/* Fragment information */
 14 87a52e04 2005-12-26 devnull 	uchar	ttl;		/* Time to live */
 15 87a52e04 2005-12-26 devnull 	uchar	proto;		/* Protocol */
 16 87a52e04 2005-12-26 devnull 	uchar	ipcksum[2];	/* Header checksum */
 17 87a52e04 2005-12-26 devnull 	uchar	src[4];		/* Ip source */
 18 87a52e04 2005-12-26 devnull 	uchar	dst[4];		/* Ip destination */
 19 87a52e04 2005-12-26 devnull 	uchar	type;
 20 87a52e04 2005-12-26 devnull 	uchar	code;
 21 87a52e04 2005-12-26 devnull 	uchar	cksum[2];
 22 87a52e04 2005-12-26 devnull 	uchar	icmpid[2];
 23 87a52e04 2005-12-26 devnull 	uchar	seq[2];
 24 87a52e04 2005-12-26 devnull 	uchar	data[1];
 25 87a52e04 2005-12-26 devnull };
 26 87a52e04 2005-12-26 devnull 
 27 87a52e04 2005-12-26 devnull enum
 28 87a52e04 2005-12-26 devnull {			/* Packet Types */
 29 87a52e04 2005-12-26 devnull 	EchoReply	= 0,
 30 87a52e04 2005-12-26 devnull 	Unreachable	= 3,
 31 87a52e04 2005-12-26 devnull 	SrcQuench	= 4,
 32 87a52e04 2005-12-26 devnull 	EchoRequest	= 8,
 33 87a52e04 2005-12-26 devnull 	TimeExceed	= 11,
 34 87a52e04 2005-12-26 devnull 	Timestamp	= 13,
 35 87a52e04 2005-12-26 devnull 	TimestampReply	= 14,
 36 87a52e04 2005-12-26 devnull 	InfoRequest	= 15,
 37 87a52e04 2005-12-26 devnull 	InfoReply	= 16,
 38 87a52e04 2005-12-26 devnull 
 39 87a52e04 2005-12-26 devnull 	ICMP_IPSIZE	= 20,
 40 cbeb0b26 2006-04-01 devnull 	ICMP_HDRSIZE	= 8
 41 87a52e04 2005-12-26 devnull };
 42 87a52e04 2005-12-26 devnull 
 43 87a52e04 2005-12-26 devnull static void
 44 87a52e04 2005-12-26 devnull catch(void *a, char *msg)
 45 87a52e04 2005-12-26 devnull {
 46 87a52e04 2005-12-26 devnull 	USED(a);
 47 87a52e04 2005-12-26 devnull 	if(strstr(msg, "alarm"))
 48 87a52e04 2005-12-26 devnull 		noted(NCONT);
 49 87a52e04 2005-12-26 devnull 	else
 50 87a52e04 2005-12-26 devnull 		noted(NDFLT);
 51 87a52e04 2005-12-26 devnull }
 52 87a52e04 2005-12-26 devnull 
 53 87a52e04 2005-12-26 devnull #define MSG "dhcp probe"
 54 87a52e04 2005-12-26 devnull 
 55 87a52e04 2005-12-26 devnull /*
 56 87a52e04 2005-12-26 devnull  *  make sure noone is using the address
 57 87a52e04 2005-12-26 devnull  */
 58 87a52e04 2005-12-26 devnull int
 59 87a52e04 2005-12-26 devnull icmpecho(uchar *a)
 60 87a52e04 2005-12-26 devnull {
 61 87a52e04 2005-12-26 devnull 	int fd;
 62 87a52e04 2005-12-26 devnull 	char buf[512];
 63 87a52e04 2005-12-26 devnull 	Icmp *ip;
 64 87a52e04 2005-12-26 devnull 	int i, n, len;
 65 87a52e04 2005-12-26 devnull 	ushort sseq, x;
 66 87a52e04 2005-12-26 devnull 	int rv;
 67 87a52e04 2005-12-26 devnull 
 68 87a52e04 2005-12-26 devnull return 0;
 69 87a52e04 2005-12-26 devnull 	rv = 0;
 70 87a52e04 2005-12-26 devnull 
 71 87a52e04 2005-12-26 devnull 	sprint(buf, "%I", a);
 72 87a52e04 2005-12-26 devnull 	fd = dial(netmkaddr(buf, "icmp", "1"), 0, 0, 0);
 73 87a52e04 2005-12-26 devnull 	if(fd < 0){
 74 87a52e04 2005-12-26 devnull 		return 0;
 75 87a52e04 2005-12-26 devnull 	}
 76 87a52e04 2005-12-26 devnull 
 77 87a52e04 2005-12-26 devnull 	sseq = getpid()*time(0);
 78 87a52e04 2005-12-26 devnull 
 79 87a52e04 2005-12-26 devnull 	ip = (Icmp*)buf;
 80 87a52e04 2005-12-26 devnull 	notify(catch);
 81 87a52e04 2005-12-26 devnull 	for(i = 0; i < 3; i++){
 82 87a52e04 2005-12-26 devnull 		ip->type = EchoRequest;
 83 87a52e04 2005-12-26 devnull 		ip->code = 0;
 84 87a52e04 2005-12-26 devnull 		strcpy((char*)ip->data, MSG);
 85 87a52e04 2005-12-26 devnull 		ip->seq[0] = sseq;
 86 87a52e04 2005-12-26 devnull 		ip->seq[1] = sseq>>8;
 87 87a52e04 2005-12-26 devnull 		len = ICMP_IPSIZE+ICMP_HDRSIZE+sizeof(MSG);
 88 87a52e04 2005-12-26 devnull 
 89 87a52e04 2005-12-26 devnull 		/* send a request */
 90 87a52e04 2005-12-26 devnull 		if(write(fd, buf, len) < len)
 91 87a52e04 2005-12-26 devnull 			break;
 92 87a52e04 2005-12-26 devnull 
 93 87a52e04 2005-12-26 devnull 		/* wait 1/10th second for a reply and try again */
 94 87a52e04 2005-12-26 devnull 		alarm(100);
 95 87a52e04 2005-12-26 devnull 		n = read(fd, buf, sizeof(buf));
 96 87a52e04 2005-12-26 devnull 		alarm(0);
 97 87a52e04 2005-12-26 devnull 		if(n <= 0)
 98 87a52e04 2005-12-26 devnull 			continue;
 99 87a52e04 2005-12-26 devnull 
100 87a52e04 2005-12-26 devnull 		/* an answer to our echo request? */
101 87a52e04 2005-12-26 devnull 		x = (ip->seq[1]<<8)|ip->seq[0];
102 87a52e04 2005-12-26 devnull 		if(n >= len)
103 87a52e04 2005-12-26 devnull 		if(ip->type == EchoReply)
104 87a52e04 2005-12-26 devnull 		if(x == sseq)
105 87a52e04 2005-12-26 devnull 		if(strcmp((char*)ip->data, MSG) == 0){
106 87a52e04 2005-12-26 devnull 			rv = 1;
107 87a52e04 2005-12-26 devnull 			break;
108 87a52e04 2005-12-26 devnull 		}
109 87a52e04 2005-12-26 devnull 	}
110 87a52e04 2005-12-26 devnull 	close(fd);
111 87a52e04 2005-12-26 devnull 	return rv;
112 87a52e04 2005-12-26 devnull }