From mboxrd@z Thu Jan  1 00:00:00 1970
Message-ID: <44b3232235d0068cf251d2005740321a@rei2.9hal>
Date: Wed, 22 Aug 2012 16:47:47 +0200
From: cinap_lenrek@gmx.de
To: 9fans@9fans.net
In-Reply-To: <f18fe4ce6843cc0c4763e9ad5d691e92@kw.quanstro.net>
MIME-Version: 1.0
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Subject: Re: [9fans] dns
Topicbox-Message-UUID: add13318-ead7-11e9-9d60-3106f5b1d025

this is interesting. the p != qp->curdest check would just
support my point because it effectively checks if p is valid.
if p would be at qp->curdest, it would be past the last valid
entry and hence invalid so its not written.

but theres another thing, look in queryns() how p comes to be:

			/* find responder */
			// dnslog("queryns got reply from %I", srcip);
			for(p = qp->dest; p < qp->curdest; p++)
				if(memcmp(p->a, srcip, sizeof p->a) == 0)
					break;

			for(np = qp->dest; np < qp->curdest; np++)
				if(np->s == p->s)			<-- oops, p might be qp->curdest here
					p->nx = Maxtrans;		<-- fuck!

			rv = procansw(qp, &m, srcip, depth, p);

i think we also need to check p != qp->curdest before that
2nd for loop or it would trash the entry at curdist.

@@ -1439,9 +1438,10 @@
 					break;

 			/* remove all addrs of responding server from list */
-			for(np = qp->dest; np < qp->curdest; np++)
-				if(np->s == p->s)
-					p->nx = Maxtrans;
+			if(p != qp->curdest)
+				for(np = qp->dest; np < qp->curdest; np++)
+					if(np->s == p->s)
+						p->nx = Maxtrans;

 			/* free or incorporate RRs in m */
 			rv = procansw(qp, &m, srcip, depth, p);

--
cinap