/*  * This file is part of the UCB release of Plan 9. It is subject to the license * terms in the LICENSE file found in the top-level directory of this * distribution and at http://akaros.cs.berkeley.edu/files/Plan9License. No * part of the UCB release of Plan 9, including this file, may be copied, * modified, propagated, or distributed except according to the terms contained * in the LICENSE file. */ #include <u.h>#include <libc.h>#include <ip.h>#include <bio.h>#include <ndb.h>#include <ctype.h>#include "dat.h" /* *  format of a binding entry: *	char ipaddr[32]; *	char id[32]; *	char hwa[32]; *	char otime[10]; */Binding *bcache;uchar bfirst[IPaddrlen];char *binddir = "/lib/ndb/dhcp"; /* *  convert a byte array to hex */static charhex(int x){	if(x < 10)		return x + '0';	return x - 10 + 'a';}extern char*tohex(char *hdr, uchar *p, int len){	char *s, *sp;	int hlen; 	hlen = strlen(hdr);	s = malloc(hlen + 2*len + 1);	sp = s;	strcpy(sp, hdr);	sp += hlen;	for(; len > 0; len--){		*sp++ = hex(*p>>4);		*sp++ = hex(*p & 0xf);		p++;	}	*sp = 0;	return s;} /* *  convert a client id to a string.  If it's already *  ascii, leave it be.  Otherwise, convert it to hex. */extern char*toid(uchar *p, int n){	int i;	char *s; 	for(i = 0; i < n; i++)		if(!isprint(p[i]))			return tohex("id", p, n);	s = malloc(n + 1);	memmove(s, p, n);	s[n] = 0;	return s;} /* *  increment an ip address */static voidincip(uchar *ip){	int i, x; 	for(i = IPaddrlen-1; i >= 0; i--){		x = ip[i];		x++;		ip[i] = x;		if((x & 0x100) == 0)			break;	}} /* *  find a binding for an id or hardware address */static intlockopen(char *file){	char err[ERRMAX];	int fd, tries; 	for(tries = 0; tries < 5; tries++){		fd = open(file, ORDWR);		if(fd >= 0)			return fd;		errstr(err, sizeof err);		if(strstr(err, "lock")){			/* wait for other process to let go of lock */			sleep(250); 			/* try again */			continue;		}		if(strstr(err, "exist")){			/* no file, create an exclusive access file */			fd = create(file, ORDWR, DMEXCL|0664);			if(fd >= 0)				return fd;		}	}	return -1;} voidsetbinding(Binding *b, char *id, long t){	if(b->boundto)		free(b->boundto); 	b->boundto = strdup(id);	b->lease = t;} static voidparsebinding(Binding *b, char *buf){	long t;	char *id, *p; 	/* parse */	t = atoi(buf);	id = strchr(buf, '\n');	if(id){		*id++ = 0;		p = strchr(id, '\n');		if(p)			*p = 0;	} else		id = ""; 	/* replace any past info */	setbinding(b, id, t);} static intwritebinding(int fd, Binding *b){	Dir *d; 	seek(fd, 0, 0);	if(fprint(fd, "%ld\n%s\n", b->lease, b->boundto) < 0)		return -1;	d = dirfstat(fd);	if(d == nil)		return -1;	b->q.type = d->qid.type;	b->q.path = d->qid.path;	b->q.vers = d->qid.vers;	free(d);	return 0;} /* *  synchronize cached binding with file.  the file always wins. */intsyncbinding(Binding *b, int returnfd){	char buf[512];	int i, fd;	Dir *d; 	snprint(buf, sizeof(buf), "%s/%I", binddir, b->ip);	fd = lockopen(buf);	if(fd < 0){		/* assume someone else is using it */		b->lease = time(0) + OfferTimeout;		return -1;	} 	/* reread if changed */	d = dirfstat(fd);	if(d != nil)	/* BUG? */	if(d->qid.type != b->q.type || d->qid.path != b->q.path || d->qid.vers != b->q.vers){		i = read(fd, buf, sizeof(buf)-1);		if(i < 0)			i = 0;		buf[i] = 0;		parsebinding(b, buf);		b->lasttouched = d->mtime;		b->q.path = d->qid.path;		b->q.vers = d->qid.vers;	} 	free(d); 	if(returnfd)		return fd; 	close(fd);	return 0;} extern intsamenet(uchar *ip, Info *iip){	uchar x[IPaddrlen]; 	maskip(iip->ipmask, ip, x);	return ipcmp(x, iip->ipnet) == 0;} /* *  create a record for each binding */extern voidinitbinding(uchar *first, int n){	while(n-- > 0){		iptobinding(first, 1);		incip(first);	}} /* *  find a binding for a specific ip address */extern Binding*iptobinding(uchar *ip, int mk){	Binding *b; 	for(b = bcache; b; b = b->next){		if(ipcmp(b->ip, ip) == 0){			syncbinding(b, 0);			return b;		}	} 	if(mk == 0)		return 0;	b = malloc(sizeof(*b));	memset(b, 0, sizeof(*b));	ipmove(b->ip, ip);	b->next = bcache;	bcache = b;	syncbinding(b, 0);	return b;} static voidlognolease(Binding *b){	/* renew the old binding, and hope it eventually goes away */	b->offer = 5*60;	commitbinding(b); 	/* complain if we haven't in the last 5 minutes */	if(now - b->lastcomplained < 5*60)		return;	syslog(0, blog, "dhcp: lease for %I to %s ended at %ld but still in use\n",		b->ip, b->boundto != nil ? b->boundto : "?", b->lease);	b->lastcomplained = now;} /* *  find a free binding for a hw addr or id on the same network as iip */extern Binding*idtobinding(char *id, Info *iip, int ping){	Binding *b, *oldest;	int oldesttime; 	/*	 *  first look for an old binding that matches.  that way	 *  clients will tend to keep the same ip addresses.	 */	for(b = bcache; b; b = b->next){		if(b->boundto && strcmp(b->boundto, id) == 0){			if(!samenet(b->ip, iip))				continue; 			/* check with the other servers */			syncbinding(b, 0);			if(strcmp(b->boundto, id) == 0)				return b;		}	} 	/*	 *  look for oldest binding that we think is unused	 */	for(;;){		oldest = nil;		oldesttime = 0;		for(b = bcache; b; b = b->next){			if(b->tried != now)			if(b->lease < now && b->expoffer < now && samenet(b->ip, iip))			if(oldest == nil || b->lasttouched < oldesttime){				/* sync and check again */				syncbinding(b, 0);				if(b->lease < now && b->expoffer < now && samenet(b->ip, iip))				if(oldest == nil || b->lasttouched < oldesttime){					oldest = b;					oldesttime = b->lasttouched;				}			}		}		if(oldest == nil)			break; 		/* make sure noone is still using it */		oldest->tried = now;		if(ping == 0 || icmpecho(oldest->ip) == 0)			return oldest; 		lognolease(oldest);	/* sets lastcomplained */	} 	/* try all bindings */	for(b = bcache; b; b = b->next){		syncbinding(b, 0);		if(b->tried != now)		if(b->lease < now && b->expoffer < now && samenet(b->ip, iip)){			b->tried = now;			if(ping == 0 || icmpecho(b->ip) == 0)				return b; 			lognolease(b);		}	} 	/* nothing worked, give up */	return 0;} /* *  create an offer */extern voidmkoffer(Binding *b, char *id, long leasetime){	if(leasetime <= 0){		if(b->lease > now + minlease)			leasetime = b->lease - now;		else			leasetime = minlease;	}	if(b->offeredto)		free(b->offeredto);	b->offeredto = strdup(id);	b->offer = leasetime;	b->expoffer = now + OfferTimeout;} /* *  find an offer for this id */extern Binding*idtooffer(char *id, Info *iip){	Binding *b; 	/* look for an offer to this id */	for(b = bcache; b; b = b->next){		if(b->offeredto && strcmp(b->offeredto, id) == 0 && samenet(b->ip, iip)){			/* make sure some other system hasn't stolen it */			syncbinding(b, 0);			if(b->lease < now			|| (b->boundto && strcmp(b->boundto, b->offeredto) == 0))				return b;		}	}	return 0;} /* *  commit a lease, this could fail */extern intcommitbinding(Binding *b){	int fd;	long now; 	now = time(0); 	if(b->offeredto == 0)		return -1;	fd = syncbinding(b, 1);	if(fd < 0)		return -1;	if(b->lease > now && b->boundto && strcmp(b->boundto, b->offeredto) != 0){		close(fd);		return -1;	}	setbinding(b, b->offeredto, now + b->offer);	b->lasttouched = now;		if(writebinding(fd, b) < 0){		close(fd);		return -1;	}	close(fd);	return 0;} /* *  commit a lease, this could fail */extern intreleasebinding(Binding *b, char *id){	int fd;	long now; 	now = time(0); 	fd = syncbinding(b, 1);	if(fd < 0)		return -1;	if(b->lease > now && b->boundto && strcmp(b->boundto, id) != 0){		close(fd);		return -1;	}	b->lease = 0;	b->expoffer = 0;		if(writebinding(fd, b) < 0){		close(fd);		return -1;	}	close(fd);	return 0;}