[reSIProcate] Question about thread-safety in RRVip

[Byron Campen <bcampen@xxxxxxxxxxxx>]

While working on the greylisting code, I have noticed something disturbing. From what I can tell, the RRVip ends up being accessed by two different threads. 

There are the access that comes from a callback to DnsStub::Query::process() from ares:

*snip*

      if (bGotAnswers)

      {

         mReQuery = 0;

         DnsResourceRecordsByPtr result;

         int queryStatus = 0;

         RRCache::instance()->lookup(targetToQuery, mRRType, mProto, result, queryStatus);

         if (mTransform) mTransform->transform(targetToQuery, mRRType, result);

         mResultConverter->notifyUser(mTarget, queryStatus, mStub.errorMessage(queryStatus), result, mSink);

      }

*snip*

and there are the accesses that come from the stack's thread, through DnsResult

in DnsResult::whitelistLast()

*snip*

void

DnsResult::whitelistLast()

{

   std::vector<Item>::iterator i;

   for (i=mLastReturnedPath.begin(); i!=mLastReturnedPath.end(); ++i)

   {

      DebugLog( << "Whitelisting " << i->domain << "(" << i->rrType << "): " << i->value);

      mVip.vip(i->domain, i->rrType, i->value);

   }

}

*snip*

in DnsResult::blacklistLastReturnedResult()

*snip*

void DnsResult::blacklistLastReturnedResult(UInt64 expiry)

{

   assert(!mLastReturnedPath.empty());

   assert(mLastReturnedPath.size()<=3);

   Item top = mLastReturnedPath.back();

   DnsResult::blacklist(mLastResult,expiry);

   DebugLog( << "Remove vip " << top.domain << "(" << top.rrType << ")");

   mVip.removeVip(top.domain, top.rrType);

}

*snip*

Unless I am mistaken about the call to DnsStub::Query::process() coming from ares as a callback, this needs to be fixed pronto.

Best regards,

Byron Campen

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