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#include <u.h>
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#include <libc.h>
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#include <bio.h>
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#include <ndb.h>
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#include <ndbhf.h>
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static void nstrcpy(char*, char*, int);
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static void mkptrname(char*, char*, int);
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static Ndbtuple *doquery(int, char *dn, char *type);
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/*
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 *  search for a tuple that has the given 'attr=val' and also 'rattr=x'.
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 *  copy 'x' into 'buf' and return the whole tuple.
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 *
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 *  return 0 if not found.
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 */
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Ndbtuple*
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dnsquery(char *net, char *val, char *type)
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{
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	char rip[128];
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	char *p;
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	Ndbtuple *t;
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	int fd;
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	/* if the address is V4 or V6 null address, give up early */
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	if(strcmp(val, "::") == 0 || strcmp(val, "0.0.0.0") == 0)
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		return nil;
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	if(net == nil)
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		net = "/net";
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	snprint(rip, sizeof(rip), "%s/dns", net);
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	fd = open(rip, ORDWR);
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	if(fd < 0){
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		if(strcmp(net, "/net") == 0)
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			snprint(rip, sizeof(rip), "/srv/dns");
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		else {
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			snprint(rip, sizeof(rip), "/srv/dns%s", net);
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			p = strrchr(rip, '/');
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			*p = '_';
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		}
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		fd = open(rip, ORDWR);
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		if(fd < 0)
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			return nil;
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		if(mount(fd, -1, net, MBEFORE, "") < 0){
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			close(fd);
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			return nil;
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		}
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		/* fd is now closed */
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		snprint(rip, sizeof(rip), "%s/dns", net);
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		fd = open(rip, ORDWR);
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		if(fd < 0)
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			return nil;
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	}
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	/* zero out the error string */
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	werrstr("");
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	/* if this is a reverse lookup, first lookup the domain name */
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	if(strcmp(type, "ptr") == 0){
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		mkptrname(val, rip, sizeof rip);
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		t = doquery(fd, rip, "ptr");
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	} else
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		t = doquery(fd, val, type);
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	/*
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	 * TODO: make fd static and keep it open to reduce 9P traffic
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	 * walking to /net*^/dns.  Must be prepared to re-open it on error.
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	 */
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	close(fd);
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	ndbsetmalloctag(t, getcallerpc(&net));
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	return t;
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}
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/*
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 *  convert address into a reverse lookup address
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 */
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static void
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mkptrname(char *ip, char *rip, int rlen)
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{
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	char buf[128];
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	char *p, *np;
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	int len;
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	if(cistrstr(ip, "in-addr.arpa") || cistrstr(ip, "ip6.arpa")){
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		nstrcpy(rip, ip, rlen);
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		return;
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	}
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	nstrcpy(buf, ip, sizeof buf);
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	for(p = buf; *p; p++)
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		;
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	*p = '.';
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	np = rip;
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	len = 0;
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	while(p >= buf){
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		len++;
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		p--;
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		if(*p == '.'){
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			memmove(np, p+1, len);
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			np += len;
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			len = 0;
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		}
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	}
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	memmove(np, p+1, len);
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	np += len;
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	strcpy(np, "in-addr.arpa");
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}
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static void
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nstrcpy(char *to, char *from, int len)
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{
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	strncpy(to, from, len);
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	to[len-1] = 0;
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}
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static Ndbtuple*
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doquery(int fd, char *dn, char *type)
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{
119 
	char buf[1024];
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	int n;
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	Ndbtuple *t, *first, *last;
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	seek(fd, 0, 0);
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	snprint(buf, sizeof(buf), "!%s %s", dn, type);
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	if(write(fd, buf, strlen(buf)) < 0)
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		return nil;
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128 
	seek(fd, 0, 0);
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130 
	first = last = nil;
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132 
	for(;;){
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		n = read(fd, buf, sizeof(buf)-2);
134 
		if(n <= 0)
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			break;
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		if(buf[n-1] != '\n')
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			buf[n++] = '\n';	/* ndbparsline needs a trailing new line */
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		buf[n] = 0;
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140 
		/* check for the error condition */
141 
		if(buf[0] == '!'){
142 
			werrstr("%s", buf+1);
143 
			return nil;
144 
		}
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146 
		t = _ndbparseline(buf);
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		if(t != nil){
148 
			if(first)
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				last->entry = t;
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			else
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				first = t;
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			last = t;
153 
 
154 
			while(last->entry)
155 
				last = last->entry;
156 
		}
157 
	}
158 
 
159 
	ndbsetmalloctag(first, getcallerpc(&fd));
160 
	return first;
161 
}