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ndb/dnsquery: handle .ip6.arpa names, don't mount the dns service

--- a/sys/man/8/ndb

+++ b/sys/man/8/ndb

@@ -49,7 +49,7 @@

 .B -s

 ]

 [

-.I server

+.I /net/cs

 [

 .I addr...

 ]

@@ -91,6 +91,8 @@

 .B ndb/dnsquery

 [

 .B -x

+] [

+.I /net/dns

 ]

 .br

 .B ndb/dnsdebug

--- a/sys/src/cmd/ndb/dnsquery.c

+++ b/sys/src/cmd/ndb/dnsquery.c

@@ -6,35 +6,6 @@

 #include "dns.h"

 #include "ip.h"

-static int domount;

-static char *mtpt, *dns, *srv;

-

-static int

-setup(int argc, char **argv)

-{

-	int fd;

-

-	if(argc == 1){

-		domount = 0;

-		mtpt = argv[0];

-	}

-

-	fd = open(dns, ORDWR);

-	if(fd < 0){

-		if(domount == 0)

-			sysfatal("can't open %s: %r", dns);

-		fd = open(srv, ORDWR);

-		if(fd < 0)

-			sysfatal("can't open %s: %r", srv);

-		if(mount(fd, -1, mtpt, MBEFORE, "") < 0)

-			sysfatal("can't mount(%s, %s): %r", srv, mtpt);

-		fd = open(dns, ORDWR);

-		if(fd < 0)

-			sysfatal("can't open %s: %r", dns);

-	}

-	return fd;

-}

-

 static void

 querydns(int fd, char *line, int n)

 {

@@ -52,11 +23,37 @@

 	}

 }

+/*

+ *  convert address into a reverse lookup address

+ */

 static void

+mkptrname(char *ip, char *rip, int rlen)

+{

+	uchar a[IPaddrlen];

+	char *p, *e;

+	int i;

+

+	if(cistrstr(ip, "in-addr.arpa") || cistrstr(ip, "ip6.arpa") || parseip(a, ip) == -1)

+		snprint(rip, rlen, "%s", ip);

+	else if(isv4(a))

+		snprint(rip, rlen, "%ud.%ud.%ud.%ud.in-addr.arpa",

+			a[15], a[14], a[13], a[12]);

+	else{

+		p = rip;

+		e = rip + rlen;

+		for(i = 15; i >= 0; i--){

+			p = seprint(p, e, "%ux.", a[i]&0xf);

+			p = seprint(p, e, "%ux.", a[i]>>4);

+		}

+		seprint(p, e, "ip6.arpa");

+	}

+}

+

+static void

 query(int fd)

 {

-	int n, len;

-	char *lp, *p, *np;

+	int n;

+	char *lp;

 	char buf[1024], line[1024];

 	Biobuf in;

@@ -84,31 +81,10 @@

 				n += 3;

 			}

-		/* inverse queries may need to be permuted */

-		if(n > 4 && strcmp(" ptr", &line[n-4]) == 0 &&

-		    cistrstr(line, ".arpa") == nil){

-			/* TODO: reversing v6 addrs is harder */

-			for(p = line; *p; p++)

-				if(*p == ' '){

-					*p = '.';

-					break;

-				}

-			np = buf;

-			len = 0;

-			while(p >= line){

-				len++;

-				p--;

-				if(*p == '.'){

-					memmove(np, p+1, len);

-					np += len;

-					len = 0;

-				}

-			}

-			memmove(np, p+1, len);

-			np += len;

-			strcpy(np, "in-addr.arpa ptr");	/* TODO: ip6.arpa for v6 */

-			strcpy(line, buf);

-			n = strlen(line);

+		if(n > 4 && strcmp(" ptr", &line[n-4]) == 0){

+			line[n-4] = 0;

+			mkptrname(line, buf, sizeof buf);

+			n = snprint(line, sizeof line, "%s ptr", buf);

 		}

 		querydns(fd, line, n);

@@ -119,21 +95,25 @@

 void

 main(int argc, char *argv[])

 {

-	mtpt = "/net";

-	dns = "/net/dns";

-	srv = "/srv/dns";

-	domount = 1;

+	char *dns  = "/net/dns";

+	int fd;

+

 	ARGBEGIN {

 	case 'x':

-		mtpt = "/net.alt";

 		dns = "/net.alt/dns";

-		srv = "/srv/dns_net.alt";

 		break;

 	default:

-		fprint(2, "usage: %s [-x] [dns-mount-point]\n", argv0);

+		fprint(2, "usage: %s [-x] [/net/dns]\n", argv0);

 		exits("usage");

 	} ARGEND;

-	query(setup(argc, argv));

+	if(argc > 0)

+		dns = argv[0];

+

+	fd = open(dns, ORDWR);

+	if(fd < 0)

+		sysfatal("can't open %s: %r", dns);

+

+	query(fd);

 	exits(0);

 }