add dns

1 files changed, 228 insertions, 0 deletions

diff --git a/src/cmd/ndb/dnudpserver.c b/src/cmd/ndb/dnudpserver.c
new file mode 100755
index 00000000..f0ed37cd
--- /dev/null
+++ b/src/cmd/ndb/dnudpserver.c
@@ -0,0 +1,228 @@
+#include <u.h>
+#include <libc.h>
+#include <ip.h>
+#include <bio.h>
+#include <ndb.h>
+#include "dns.h"
+
+static int	udpannounce(char*);
+static void	reply(int, uchar*, DNSmsg*, Request*);
+
+extern char *logfile;
+
+static void
+ding(void *x, char *msg)
+{
+	USED(x);
+	if(strcmp(msg, "alarm") == 0)
+		noted(NCONT);
+	else
+		noted(NDFLT);
+}
+
+typedef struct Inprogress Inprogress;
+struct Inprogress
+{
+	int	inuse;
+	OUdphdr	uh;
+	DN	*owner;
+	int	type;
+	int	id;
+};
+Inprogress inprog[Maxactive+2];
+
+/*
+ *  record client id and ignore retransmissions.
+ *  we're still single thread at this point.
+ */
+static Inprogress*
+clientrxmit(DNSmsg *req, uchar *buf)
+{
+	Inprogress *p, *empty;
+	OUdphdr *uh;
+
+	uh = (OUdphdr *)buf;
+	empty = 0;
+	for(p = inprog; p < &inprog[Maxactive]; p++){
+		if(p->inuse == 0){
+			if(empty == 0)
+				empty = p;
+			continue;
+		}
+		if(req->id == p->id)
+		if(req->qd->owner == p->owner)
+		if(req->qd->type == p->type)
+		if(memcmp(uh, &p->uh, OUdphdrsize) == 0)
+			return 0;
+	}
+	if(empty == 0)
+		return 0;	/* shouldn't happen - see slave() and definition of Maxactive */
+
+	empty->id = req->id;
+	empty->owner = req->qd->owner;
+	empty->type = req->qd->type;
+	memmove(&empty->uh, uh, OUdphdrsize);
+	empty->inuse = 1;
+	return empty;
+}
+
+/*
+ *  a process to act as a dns server for outside reqeusts
+ */
+void
+dnudpserver(char *mntpt)
+{
+	int fd, len, op;
+	Request req;
+	DNSmsg reqmsg, repmsg;
+	uchar buf[OUdphdrsize + Maxudp + 1024];
+	char *err;
+	Inprogress *p;
+	char tname[32];
+	OUdphdr *uh;
+
+	/* fork sharing text, data, and bss with parent */
+	switch(rfork(RFPROC|RFNOTEG|RFMEM|RFNOWAIT)){
+	case -1:
+		break;
+	case 0:
+		break;
+	default:
+		return;
+	}
+
+	fd = -1;
+	notify(ding);
+restart:
+	if(fd >= 0)
+		close(fd);
+	while((fd = udpannounce(mntpt)) < 0)
+		sleep(5000);
+	if(setjmp(req.mret))
+		putactivity();
+	req.isslave = 0;
+
+	/* loop on requests */
+	for(;; putactivity()){
+		memset(&repmsg, 0, sizeof(repmsg));
+		memset(&reqmsg, 0, sizeof(reqmsg));
+		alarm(60*1000);
+		len = udpread(fd, (OUdphdr*)buf, buf+OUdphdrsize, sizeof(buf)-OUdphdrsize);
+		alarm(0);
+		if(len <= 0)
+			goto restart;
+		uh = (OUdphdr*)buf;
+		getactivity(&req);
+		req.aborttime = now + 30;	/* don't spend more than 30 seconds */
+		err = convM2DNS(&buf[OUdphdrsize], len, &reqmsg);
+		if(err){
+			syslog(0, logfile, "server: input error: %s from %I", err, buf);
+			continue;
+		}
+		if(reqmsg.qdcount < 1){
+			syslog(0, logfile, "server: no questions from %I", buf);
+			goto freereq;
+		}
+		if(reqmsg.flags & Fresp){
+			syslog(0, logfile, "server: reply not request from %I", buf);
+			goto freereq;
+		}
+		op = reqmsg.flags & Omask;
+		if(op != Oquery && op != Onotify){
+			syslog(0, logfile, "server: op %d from %I", reqmsg.flags & Omask, buf);
+			goto freereq;
+		}
+
+		if(debug || (trace && subsume(trace, reqmsg.qd->owner->name))){
+			syslog(0, logfile, "%d: serve (%I/%d) %d %s %s",
+				req.id, buf, ((uh->rport[0])<<8)+uh->rport[1],
+				reqmsg.id,
+				reqmsg.qd->owner->name,
+				rrname(reqmsg.qd->type, tname, sizeof tname));
+		}
+
+		p = clientrxmit(&reqmsg, buf);
+		if(p == 0){
+			if(debug)
+				syslog(0, logfile, "%d: duplicate", req.id);
+			goto freereq;
+		}
+
+		/* loop through each question */
+		while(reqmsg.qd){
+			memset(&repmsg, 0, sizeof(repmsg));
+			switch(op){
+			case Oquery:
+				dnserver(&reqmsg, &repmsg, &req);
+				break;
+			case Onotify:
+				dnnotify(&reqmsg, &repmsg, &req);
+				break;
+			}
+			reply(fd, buf, &repmsg, &req);
+			rrfreelist(repmsg.qd);
+			rrfreelist(repmsg.an);
+			rrfreelist(repmsg.ns);
+			rrfreelist(repmsg.ar);
+		}
+
+		p->inuse = 0;
+
+freereq:
+		rrfreelist(reqmsg.qd);
+		rrfreelist(reqmsg.an);
+		rrfreelist(reqmsg.ns);
+		rrfreelist(reqmsg.ar);
+
+		if(req.isslave){
+			putactivity();
+			_exits(0);
+		}
+
+	}
+}
+
+/*
+ *  announce on udp port
+ */
+static int
+udpannounce(char *mntpt)
+{
+	int fd;
+	char buf[40];
+	
+	USED(mntpt);
+	
+	if((fd=announce("udp!*!nameserver", buf)) < 0)
+		warning("can't announce on dns udp port");
+	return fd;
+}
+
+static void
+reply(int fd, uchar *buf, DNSmsg *rep, Request *reqp)
+{
+	int len;
+	char tname[32];
+	RR *rp;
+
+	if(debug || (trace && subsume(trace, rep->qd->owner->name)))
+		syslog(0, logfile, "%d: reply (%I/%d) %d %s %s an %R ns %R ar %R",
+			reqp->id, buf, ((buf[4])<<8)+buf[5],
+			rep->id, rep->qd->owner->name,
+			rrname(rep->qd->type, tname, sizeof tname), rep->an, rep->ns, rep->ar);
+
+	len = convDNS2M(rep, &buf[OUdphdrsize], Maxudp);
+	if(len <= 0){
+		syslog(0, logfile, "error converting reply: %s %d", rep->qd->owner->name,
+			rep->qd->type);
+		for(rp = rep->an; rp; rp = rp->next)
+			syslog(0, logfile, "an %R", rp);
+		for(rp = rep->ns; rp; rp = rp->next)
+			syslog(0, logfile, "ns %R", rp);
+		for(rp = rep->ar; rp; rp = rp->next)
+			syslog(0, logfile, "ar %R", rp);
+		return;
+	}
+	if(udpwrite(fd, (OUdphdr*)buf, buf+OUdphdrsize, len) != len)
+		syslog(0, logfile, "error sending reply: %r");
+}