From owner-freebsd-hackers  Sun Dec  9 11:19:57 2001
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To: chris@FreeBSD.ORG
Cc: Igor M Podlesny <poige@morning.ru>, freebsd-hackers@FreeBSD.ORG
Subject: Re: jail.c.patch (allowing to use hostnames when invoking jail(8)) 
In-Reply-To: <20011125112748.B511@holly.calldei.com>; from chris@FreeBSD.ORG on "Sun, 25 Nov 2001 11:27:48 -0600"
Date: Sun, 09 Dec 2001 19:19:43 +0000
From: Dima Dorfman <dima@trit.org>
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Chris Costello <chris@FreeBSD.ORG> wrote:
> On Saturday, November 24, 2001, Igor M Podlesny wrote:
> >         i = inet_aton(argv[3], &in);
> > -       if (!i)
> > -               errx(1, "Couldn't make sense of ip-number\n");
> > +       if (!i) {
> > +               /* check if it is resolveable */
> > +               struct hostent *hp;
> > +               hp = gethostbyname(argv[3]);
> > +               if (hp == NULL) {
> > +                       errx(1, "Couldn't make sense of the jail address\n");
> > +               }
> > +               else {
> > +                       char **p = hp->h_addr_list;
> > +                       if (p[1] != NULL) {
> > +                               errx(1, "Jail should have only one ip-address associated with!\n");
> > +                       }
> > +                       else {
> > +                               memcpy(&in.s_addr, p[0], sizeof(in.s_addr));
> > +                       }
> > +               }
> > +       }
> 
>    I'd rewrite the above (`i = inet_aton' all the way down) as
> 
>      hp = gethostbyname(argv[3]);
>      if (hp == NULL) {
>              errx(1, "%s: %s", argv[3], hstrerror(h_errno));
>      }
>      in = *(struct in_addr *)hp->h_addr_list[0];
> 
>    This makes the call to inet_aton() unnecessary (and really
> shortens the code!).

As discussed off-list, this is a good idea.  Attached is the final
patch that I plan to commit unless I hear objections.  Please review.

Thanks.

Index: jail.8
===================================================================
RCS file: /ref/cvsf/src/usr.sbin/jail/jail.8,v
retrieving revision 1.30
diff -u -r1.30 jail.8
--- jail.8	2001/09/03 15:42:10	1.30
+++ jail.8	2001/12/09 19:14:30
@@ -43,7 +43,7 @@
 .Nm
 .Ar path
 .Ar hostname
-.Ar ip-number
+.Ar hostname
 .Ar command
 .Ar ...
 .Sh DESCRIPTION
Index: jail.c
===================================================================
RCS file: /ref/cvsf/src/usr.sbin/jail/jail.c,v
retrieving revision 1.7
diff -u -r1.7 jail.c
--- jail.c	2001/06/24 20:28:19	1.7
+++ jail.c	2001/12/09 19:14:11
@@ -17,6 +17,7 @@
 #include <arpa/inet.h>
 
 #include <err.h>
+#include <netdb.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -25,12 +26,13 @@
 int
 main(int argc, char **argv)
 {
+	struct hostent *hp;
 	struct jail j;
 	int i;
 	struct in_addr in;
 
 	if (argc < 5) 
-		errx(1, "Usage: %s path hostname ip-number command ...\n",
+               errx(1, "Usage: %s path hostname hostname command ...\n",
 		    argv[0]);
 	i = chdir(argv[1]);
 	if (i)
@@ -39,9 +41,11 @@
 	j.version = 0;
 	j.path = argv[1];
 	j.hostname = argv[2];
+	hp = gethostbyname(argv[3]);
+	if (hp == NULL)
+		errx(1, "gethostbyname(%s): %s", argv[3], hstrerror(h_errno));
 	i = inet_aton(argv[3], &in);
-	if (!i)
-		errx(1, "Couldn't make sense of ip-number\n");
+	in = *(struct in_addr *)hp->h_addr;
 	j.ip_number = ntohl(in.s_addr);
 	i = jail(&j);
 	if (i)

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