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WebSVN – planix.SVN – Blame – /os/branches/feature_unix/sys/src/cmd/cifs/ping.c – Rev 2

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#include <u.h>
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#include <libc.h>
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#include <fcall.h>
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#include <thread.h>
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#include <libsec.h>
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#include <9p.h>
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extern char *Debug;
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typedef struct Pingcache Pingcache;
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struct Pingcache {
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	Pingcache*next;
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	long	rtt;
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	char	*host;
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	long	expire;
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};
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typedef struct {
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	uchar	vihl;		/* Version and header length */
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	uchar	tos;		/* Type of service */
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	uchar	length[2];	/* packet length */
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	uchar	id[2];		/* Identification */
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	uchar	frag[2];	/* Fragment information */
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	uchar	ttl;		/* Time to live */
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	uchar	proto;		/* Protocol */
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	uchar	ipcksum[2];	/* Header checksum */
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	uchar	src[4];		/* Ip source */
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	uchar	dst[4];		/* Ip destination */
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	uchar	type;
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	uchar	code;
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	uchar	cksum[2];
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	uchar	icmpid[2];
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	uchar	seq[2];
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	uchar	data[1];
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} Icmp;
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enum {			/* Packet Types */
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	EchoReply	= 0,
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	Unreachable	= 3,
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	SrcQuench	= 4,
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	EchoRequest	= 8,
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	TimeExceed	= 11,
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	Timestamp	= 13,
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	TimestampReply	= 14,
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	InfoRequest	= 15,
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	InfoReply	= 16,
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	ICMP_IPSIZE	= 20,
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	ICMP_HDRSIZE	= 8,
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	Npings		= 8,
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	Payload		= 32,
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	Cachetime	= 60,
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};
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static Pingcache *Cache;
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/*
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 * We ignore the first result as that is probably bigger
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 * than expected due to IP sorting out the routing to the host
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 */
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int
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ping(char *host, int timeout)
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{
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	int rtt, fd, i, seq;
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	long now;
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	vlong then;
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	uchar buf[128];
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	Icmp *ip;
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	Pingcache *c;
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	now = time(nil);
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	for(c = Cache; c; c = c->next)
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		if(strcmp(c->host, host) == 0 && now < c->expire){
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			if(Debug && strstr(Debug, "dfs") != nil)
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				print("\t\tping host=%s timeout=%d - cache hit\n",
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					host, timeout);
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			return c->rtt;
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		}
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	rtt = -1;
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	ip = (Icmp*)buf;
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	if((fd = dial(netmkaddr(host, "icmp", "1"), 0, 0, 0)) == -1)
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		goto fail;
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	for(seq = 0; seq < Npings; seq++){
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		then = nsec();
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		for(i = Payload; i < sizeof buf; i++)
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			buf[i] = i + seq;
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		ip->type = EchoRequest;
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		ip->code = 0;
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		ip->seq[0] = seq;
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		ip->seq[1] = seq;
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		alarm(timeout);
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		if(write(fd, ip, sizeof buf) != sizeof buf ||
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		    read(fd, ip, sizeof buf) != sizeof buf)
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			goto fail;
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		alarm(0);
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		if(ip->type != EchoReply || ip->code != 0 ||
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		    ip->seq[0] != seq || ip->seq[1] != seq)
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			goto fail;
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		for(i = Payload; i < sizeof buf; i++)
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			if((uchar)buf[i] != (uchar)(i + seq))
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				goto fail;
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		rtt = (rtt + nsec() - then) / 2;
108 
	}
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fail:
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	if(fd != -1)
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		close(fd);
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113 
	if(Debug && strstr(Debug, "dfs") != nil)
114 
		print("\t\tping host=%s timeout=%d rtt=%d - failed\n",
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			host, timeout, rtt);
116 
 
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	/*
118 
	 * failures get cached too
119 
	 */
120 
	for(c = Cache; c; c = c->next)
121 
		if(strcmp(c->host, host) == 0)
122 
			break;
123 
	if(c == nil){
124 
		c = emalloc9p(sizeof(Pingcache));
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		c->host = estrdup9p(host);
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		c->next = Cache;
127 
		Cache = c;
128 
	}
129 
	c->rtt = rtt;
130 
	c->expire = now+Cachetime;
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	return rtt;
132 
}