From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Gibson <david@gibson.dropbear.id.au>
To: passt-dev@passt.top
Subject: [PATCH 2/8] conf: Use "-D none" and "-S none" instead of missing
 empty option arguments
Date: Fri, 26 Aug 2022 14:58:33 +1000
Message-ID: <20220826045839.1112152-3-david@gibson.dropbear.id.au>
In-Reply-To: <20220826045839.1112152-1-david@gibson.dropbear.id.au>
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Both the -D (--dns) and -S (--search) options take an optional argument.
If the argument is omitted the option is disabled entirely.  However,
handling the optional argument requires some ugly special case handling if
it's the last option on the command line, and has potential ambiguity with
non-option arguments used with pasta.  It can also make it more confusing
to read command lines.

Simplify the logic here by replacing the non-argument versions with an
explicit "-D none" or "-S none".

Signed-off-by: David Gibson <david(a)gibson.dropbear.id.au>
---
 conf.c  | 18 ++++--------------
 passt.1 |  7 ++++---
 2 files changed, 8 insertions(+), 17 deletions(-)

diff --git a/conf.c b/conf.c
index 4eb9e3d..6770be9 100644
--- a/conf.c
+++ b/conf.c
@@ -1022,8 +1022,8 @@ void conf(struct ctx *c, int argc, char **argv)
 		{"mac-addr",	required_argument,	NULL,		'M' },
 		{"gateway",	required_argument,	NULL,		'g' },
 		{"interface",	required_argument,	NULL,		'i' },
-		{"dns",		optional_argument,	NULL,		'D' },
-		{"search",	optional_argument,	NULL,		'S' },
+		{"dns",		required_argument,	NULL,		'D' },
+		{"search",	required_argument,	NULL,		'S' },
 		{"no-tcp",	no_argument,		&c->no_tcp,	1 },
 		{"no-udp",	no_argument,		&c->no_udp,	1 },
 		{"no-icmp",	no_argument,		&c->no_icmp,	1 },
@@ -1077,16 +1077,6 @@ void conf(struct ctx *c, int argc, char **argv)
=20
 		name =3D getopt_long(argc, argv, optstring, options, NULL);
=20
-		if ((name =3D=3D 'D' || name =3D=3D 'S') && !optarg &&
-		    optind < argc && *argv[optind] && *argv[optind] !=3D '-') {
-			if (c->mode =3D=3D MODE_PASTA) {
-				if (conf_ns_opt(c, nsdir, userns, argv[optind]))
-					optarg =3D argv[optind++];
-			} else {
-				optarg =3D argv[optind++];
-			}
-		}
-
 		switch (name) {
 		case -1:
 		case 0:
@@ -1403,7 +1393,7 @@ void conf(struct ctx *c, int argc, char **argv)
 				usage(argv[0]);
 			}
=20
-			if (!optarg) {
+			if (!strcmp(optarg, "none")) {
 				c->no_dns =3D 1;
 				break;
 			}
@@ -1430,7 +1420,7 @@ void conf(struct ctx *c, int argc, char **argv)
 				usage(argv[0]);
 			}
=20
-			if (!optarg) {
+			if (!strcmp(optarg, "none")) {
 				c->no_dns_search =3D 1;
 				break;
 			}
diff --git a/passt.1 b/passt.1
index 9bed946..14b01b2 100644
--- a/passt.1
+++ b/passt.1
@@ -171,7 +171,7 @@ version.
 Use \fIaddr\fR (IPv4 or IPv6) for DHCP, DHCPv6, NDP or DNS forwarding, as
 configured (see options \fB--no-dhcp-dns\fR, \fB--dhcp-dns\fR,
 \fB--dns-forward\fR) instead of reading addresses from \fI/etc/resolv.conf\f=
R.
-This option can be specified multiple times, and a single, empty option disa=
bles
+This option can be specified multiple times.  Specifying \fB-D none\fR disab=
les
 usage of DNS addresses altogether.
=20
 .TP
@@ -186,8 +186,9 @@ This option can be specified zero to two times (once for =
IPv4, once for IPv6).
 .BR \-S ", " \-\-search " " \fIlist
 Use space-separated \fIlist\fR for DHCP, DHCPv6, and NDP purposes, instead of
 reading entries from \fI/etc/resolv.conf\fR. See options \fB--no-dhcp-search=
\fR
-and \fB--dhcp-search\fR. A single, empty option disables the DNS domain sear=
ch
-list altogether.
+and \fB--dhcp-search\fR. \fB--search none\fR disables the DNS domain search
+list altogether (if you need to search a domain called "none" you can use
+\fB--search none.\fR).
=20
 .TP
 .BR \-\-no-dhcp-dns " " \fIaddr
--=20
2.37.2


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