[reSIProcate] Question about thread-safety in RRVip

[Byron Campen]

	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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