netdev - [iproute PATCH] ip-address: Fix filtering by negated address flags

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Message-Id: <20181113151201.19297-1-phil@nwl.cc>
Date:   Tue, 13 Nov 2018 16:12:01 +0100
From:   Phil Sutter <phil@....cc>
To:     Stephen Hemminger <stephen@...workplumber.org>
Cc:     netdev@...r.kernel.org
Subject: [iproute PATCH] ip-address: Fix filtering by negated address flags

When disabling a flag, one needs to AND with the inverse not the flag
itself. Otherwise specifying for instance 'home -nodad' will effectively
clear the flags variable.

While being at it, simplify the code a bit by merging common parts of
negated and non-negated case branches. Also allow for the "special
cases" to be inverted, too.

Fixes: f73ac674d0abf ("ip: change flag names to an array")
Signed-off-by: Phil Sutter <phil@....cc>
---
 ip/ipaddress.c | 32 ++++++++++++++++++--------------
 1 file changed, 18 insertions(+), 14 deletions(-)

diff --git a/ip/ipaddress.c b/ip/ipaddress.c
index cd8cc76a3473f..7b98877085878 100644
--- a/ip/ipaddress.c
+++ b/ip/ipaddress.c
@@ -1211,31 +1211,35 @@ static void print_ifa_flags(FILE *fp, const struct ifaddrmsg *ifa,
 
 static int get_filter(const char *arg)
 {
+	bool inv = false;
 	unsigned int i;
 
+	if (arg[0] == '-') {
+		inv = true;
+		arg++;
+	}
 	/* Special cases */
 	if (strcmp(arg, "dynamic") == 0) {
-		filter.flags &= ~IFA_F_PERMANENT;
+		if (inv)
+			filter.flags |= IFA_F_PERMANENT;
+		else
+			filter.flags &= ~IFA_F_PERMANENT;
 		filter.flagmask |= IFA_F_PERMANENT;
 	} else if (strcmp(arg, "primary") == 0) {
-		filter.flags &= ~IFA_F_SECONDARY;
+		if (inv)
+			filter.flags |= IFA_F_SECONDARY;
+		else
+			filter.flags &= ~IFA_F_SECONDARY;
 		filter.flagmask |= IFA_F_SECONDARY;
-	} else if (*arg == '-') {
-		for (i = 0; i < ARRAY_SIZE(ifa_flag_names); i++) {
-			if (strcmp(arg + 1, ifa_flag_names[i].name))
-				continue;
-
-			filter.flags &= ifa_flag_names[i].value;
-			filter.flagmask |= ifa_flag_names[i].value;
-			return 0;
-		}
-
-		return -1;
 	} else {
 		for (i = 0; i < ARRAY_SIZE(ifa_flag_names); i++) {
 			if (strcmp(arg, ifa_flag_names[i].name))
 				continue;
-			filter.flags |= ifa_flag_names[i].value;
+
+			if (inv)
+				filter.flags &= ~ifa_flag_names[i].value;
+			else
+				filter.flags |= ifa_flag_names[i].value;
 			filter.flagmask |= ifa_flag_names[i].value;
 			return 0;
 		}
-- 
2.19.0