Proper fix for "unknown argument" error message

While commit 1b8210f848631 kind of fixed the corner-case of invalid
short-options packed with others, it broke error reporting for
long-options. Revert it and deploy a proper solution:

When passing an invalid short-option, e.g. 'iptables -vaL', getopt_long
sets the variable 'optopt' to the invalid character's value. Use it for
reporting instead of optind if set.

To distinguish between invalid options and missing option arguments,
ebtables-translate optstring needs adjustment.

Fixes: 1b8210f848631 ("ebtables: Fix error message for invalid parameters")
Signed-off-by: Phil Sutter <phil@nwl.cc>

4 files changed, 50 insertions, 15 deletions

diff --git a/iptables/tests/shell/testcases/iptables/0009-unknown-arg_0 b/iptables/tests/shell/testcases/iptables/0009-unknown-arg_0
new file mode 100755
index 00000000..ac6e7439
--- /dev/null
+++ b/iptables/tests/shell/testcases/iptables/0009-unknown-arg_0
@@ -0,0 +1,31 @@
+#!/bin/bash
+
+rc=0
+
+check() {
+	local cmd="$1"
+	local msg="$2"
+
+	$XT_MULTI $cmd 2>&1 | grep -q "$msg" || {
+		echo "cmd: $XT_MULTI $1"
+		echo "exp: $msg"
+		echo "res: $($XT_MULTI $cmd 2>&1)"
+		rc=1
+	}
+}
+
+cmds="iptables ip6tables"
+[[ $XT_MULTI == *xtables-nft-multi ]] && {
+	cmds+=" ebtables"
+	cmds+=" iptables-translate"
+	cmds+=" ip6tables-translate"
+	cmds+=" ebtables-translate"
+}
+
+for cmd in $cmds; do
+	check "${cmd} --foo" 'unknown option "--foo"'
+	check "${cmd} -A" 'option "-A" requires an argument'
+	check "${cmd} -aL" 'unknown option "-a"'
+done
+
+exit $rc
diff --git a/iptables/xshared.c b/iptables/xshared.c
index f93529b1..ac51fac5 100644
--- a/iptables/xshared.c
+++ b/iptables/xshared.c
@@ -192,9 +192,12 @@ static int command_default(struct iptables_command_state *cs,
 	if (cs->c == ':')
 		xtables_error(PARAMETER_PROBLEM, "option \"%s\" "
 		              "requires an argument", cs->argv[optind-1]);
-	if (cs->c == '?')
-		xtables_error(PARAMETER_PROBLEM, "unknown option "
-			      "\"%s\"", cs->argv[optind-1]);
+	if (cs->c == '?') {
+		char optoptstr[3] = {'-', optopt, '\0'};
+
+		xtables_error(PARAMETER_PROBLEM, "unknown option \"%s\"",
+			      optopt ? optoptstr : cs->argv[optind - 1]);
+	}
 	xtables_error(PARAMETER_PROBLEM, "Unknown arg \"%s\"", optarg);
 }
 
diff --git a/iptables/xtables-eb-translate.c b/iptables/xtables-eb-translate.c
index 13b6b864..0c352720 100644
--- a/iptables/xtables-eb-translate.c
+++ b/iptables/xtables-eb-translate.c
@@ -201,7 +201,7 @@ static int do_commandeb_xlate(struct nft_handle *h, int argc, char *argv[], char
 	printf("nft ");
 	/* Getopt saves the day */
 	while ((c = getopt_long(argc, argv,
-	   "-A:D:I:N:E:X::L::Z::F::P:Vhi:o:j:c:p:s:d:t:M:", opts, NULL)) != -1) {
+	   "-:A:D:I:N:E:X::L::Z::F::P:Vhi:o:j:c:p:s:d:t:M:", opts, NULL)) != -1) {
 		cs.c = c;
 		switch (c) {
 		case 'A': /* Add a rule */
@@ -491,11 +491,7 @@ print_zero:
 			continue;
 		default:
 			ebt_check_inverse2(optarg, argc, argv);
-
-			if (ebt_command_default(&cs))
-				xtables_error(PARAMETER_PROBLEM,
-					      "Unknown argument: '%s'",
-					      argv[optind - 1]);
+			ebt_command_default(&cs);
 
 			if (command != 'A' && command != 'I' &&
 			    command != 'D')
diff --git a/iptables/xtables-eb.c b/iptables/xtables-eb.c
index 7214a767..412b5ccc 100644
--- a/iptables/xtables-eb.c
+++ b/iptables/xtables-eb.c
@@ -640,7 +640,16 @@ int ebt_command_default(struct iptables_command_state *cs)
 			return 0;
 		}
 	}
-	return 1;
+	if (cs->c == ':')
+		xtables_error(PARAMETER_PROBLEM, "option \"%s\" "
+		              "requires an argument", cs->argv[optind - 1]);
+	if (cs->c == '?') {
+		char optoptstr[3] = {'-', optopt, '\0'};
+
+		xtables_error(PARAMETER_PROBLEM, "unknown option \"%s\"",
+			      optopt ? optoptstr : cs->argv[optind - 1]);
+	}
+	xtables_error(PARAMETER_PROBLEM, "Unknown arg \"%s\"", optarg);
 }
 
 int nft_init_eb(struct nft_handle *h, const char *pname)
@@ -1084,11 +1093,7 @@ print_zero:
 			continue;
 		default:
 			ebt_check_inverse2(optarg, argc, argv);
-
-			if (ebt_command_default(&cs))
-				xtables_error(PARAMETER_PROBLEM,
-					      "Unknown argument: '%s'",
-					      argv[optind]);
+			ebt_command_default(&cs);
 
 			if (command != 'A' && command != 'I' &&
 			    command != 'D' && command != 'C' && command != 14)