#include <u.h>#include <libc.h>#include <ip.h>#include "dns.h" static RR*	doextquery(DNSmsg*, Request*, int);static void	hint(RR**, RR*); extern char *logfile; /* *  answer a dns request */voiddnserver(DNSmsg *reqp, DNSmsg *repp, Request *req){	RR *tp, *neg;	char *cp;	DN *nsdp, *dp;	Area *myarea;	char tname[32]; 	dncheck(nil, 1); 	memset(repp, 0, sizeof(*repp));	repp->id = reqp->id;	repp->flags = Fresp | Fcanrec | Oquery; 	/* move one question from reqp to repp */	tp = reqp->qd;	reqp->qd = tp->next;	tp->next = 0;	repp->qd = tp; 	if(repp->qd->owner->class != Cin){		syslog(0, logfile, "server: class %d", repp->qd->owner->class);		repp->flags = Runimplimented | Fresp | Fcanrec | Oquery;		return;	} 	myarea = inmyarea(repp->qd->owner->name);	if(myarea != nil && (repp->qd->type == Tixfr || repp->qd->type == Taxfr)){		syslog(0, logfile, "server: request %s", rrname(repp->qd->type, tname, sizeof tname));		repp->flags = Runimplimented | Fresp | Fcanrec | Oquery;		return;	} 	/*	 *  get the answer if we can	 */	if(reqp->flags & Frecurse)		neg = doextquery(repp, req, Recurse);	else		neg = doextquery(repp, req, Dontrecurse); 	/* authority is transitive */	if(myarea != nil || (repp->an && repp->an->auth))		repp->flags |= Fauth; 	/* pass on error codes */	if(repp->an == 0){		dp = dnlookup(repp->qd->owner->name, repp->qd->owner->class, 0);		if(dp->rr == 0)			if(reqp->flags & Frecurse)				repp->flags |= dp->nonexistent|Fauth;	} 	if(myarea == nil){		/*		 *  add name server if we know		 */		for(cp = repp->qd->owner->name; cp; cp = walkup(cp)){			nsdp = dnlookup(cp, repp->qd->owner->class, 0);			if(nsdp == 0)				continue;				repp->ns = rrlookup(nsdp, Tns, OKneg);			if(repp->ns){				/* don't pass on anything we know is wrong */				if(repp->ns->negative){					rrfreelist(repp->ns);					repp->ns = nil;				}				break;			}				repp->ns = dblookup(cp, repp->qd->owner->class, Tns, 0, 0);			if(repp->ns)				break;		}	} 	/*	 *  add ip addresses as hints	 */	if(repp->qd->type != Taxfr && repp->qd->type != Tixfr){		for(tp = repp->ns; tp; tp = tp->next)			hint(&repp->ar, tp);		for(tp = repp->an; tp; tp = tp->next)			hint(&repp->ar, tp);	} 	/*	 *  add an soa to the authority section to help client with negative caching	 */	if(repp->an == nil){		if(myarea != nil){			rrcopy(myarea->soarr, &tp);			rrcat(&repp->an, tp);		} else if(neg != nil) {			if(neg->negsoaowner != nil)				rrcat(&repp->an, rrlookup(neg->negsoaowner, Tsoa, NOneg));			repp->flags |= neg->negrcode;		}	} 	/*	 *  get rid of duplicates	 */	unique(repp->an);	unique(repp->ns);	unique(repp->ar); 	rrfreelist(neg); 	dncheck(nil, 1);} /* *  satisfy a recursive request.  dnlookup will handle cnames. */static RR*doextquery(DNSmsg *mp, Request *req, int recurse){	int type;	char *name;	RR *rp, *neg; 	name = mp->qd->owner->name;	type = mp->qd->type;	rp = dnresolve(name, Cin, type, req, &mp->an, 0, recurse, 1, 0); 	/* don't return soa hints as answers, it's wrong */	if(rp && rp->db && !rp->auth && rp->type == Tsoa)		rrfreelist(rp); 	/* don't let negative cached entries escape */	neg = rrremneg(&rp);	rrcat(&mp->an, rp);	return neg;} static voidhint(RR **last, RR *rp){	RR *hp; 	switch(rp->type){	case Tns:	case Tmx:	case Tmb:	case Tmf:	case Tmd:		hp = rrlookup(rp->host, Ta, NOneg);		if(hp == nil)			hp = dblookup(rp->host->name, Cin, Ta, 0, 0);		rrcat(last, hp);		break;	}}