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

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

[Phil Sutter]

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@nwl.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

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

[Stephen Hemminger]

On Tue, 13 Nov 2018 16:12:01 +0100
Phil Sutter <phil@nwl.cc> wrote:

> +	if (arg[0] == '-') {
> +		inv = true;
> +		arg++;
> +	}
The inverse logic needs to be moved into the loop handling filter names.

Otherwise, you get weirdness like "-dynamic" being accepted and not
doing what was expected.

Also, please make sure the man page matches the code.

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

[Phil Sutter]

Hi Stephen,

On Tue, Nov 13, 2018 at 02:47:59PM -0800, Stephen Hemminger wrote:
> On Tue, 13 Nov 2018 16:12:01 +0100
> Phil Sutter <phil@nwl.cc> wrote:
> 
> > +	if (arg[0] == '-') {
> > +		inv = true;
> > +		arg++;
> > +	}
> The inverse logic needs to be moved into the loop handling filter names.
> 
> Otherwise, you get weirdness like "-dynamic" being accepted and not
> doing what was expected.

I intentionally moved it there to allow for '-dynamic' and '-primary'
as well. IMO this is consistent: 'dynamic' is the inverse of 'permanent'
and 'primary' the inverse of 'secondary' but currently only '-permanent'
and '-secondary' are allowed. With my patch applied, one may specify not
only '-permanent' to get the same effect as 'dynamic' but also
'-dynamic' to get the same effect as 'permanent'. Likewise for the other
two. Did I miss something?

> Also, please make sure the man page matches the code.

Oh, right. Given the above is fine with you, I will add the man page
change in v2.

Thanks, Phil

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

[Stephen Hemminger]

On Wed, 14 Nov 2018 11:52:51 +0100
Phil Sutter <phil@nwl.cc> wrote:

> Hi Stephen,
> 
> On Tue, Nov 13, 2018 at 02:47:59PM -0800, Stephen Hemminger wrote:
> > On Tue, 13 Nov 2018 16:12:01 +0100
> > Phil Sutter <phil@nwl.cc> wrote:
> >   
> > > +	if (arg[0] == '-') {
> > > +		inv = true;
> > > +		arg++;
> > > +	}  
> > The inverse logic needs to be moved into the loop handling filter names.
> > 
> > Otherwise, you get weirdness like "-dynamic" being accepted and not
> > doing what was expected.  
> 
> I intentionally moved it there to allow for '-dynamic' and '-primary'
> as well. IMO this is consistent: 'dynamic' is the inverse of 'permanent'
> and 'primary' the inverse of 'secondary' but currently only '-permanent'
> and '-secondary' are allowed. With my patch applied, one may specify not
> only '-permanent' to get the same effect as 'dynamic' but also
> '-dynamic' to get the same effect as 'permanent'. Likewise for the other
> two. Did I miss something?
> 
> > Also, please make sure the man page matches the code.  
> 
> Oh, right. Given the above is fine with you, I will add the man page
> change in v2.
> 
> Thanks, Phil

I was thinking something like this which simplifies the logic.

diff --git a/ip/ipaddress.c b/ip/ipaddress.c
index cd8cc76a3473..3f1510383071 100644
--- a/ip/ipaddress.c
+++ b/ip/ipaddress.c
@@ -1212,37 +1212,34 @@ static void print_ifa_flags(FILE *fp, const struct ifaddrmsg *ifa,
 static int get_filter(const char *arg)
 {
 	unsigned int i;
+	bool inv = false;
 
 	/* Special cases */
 	if (strcmp(arg, "dynamic") == 0) {
-		filter.flags &= ~IFA_F_PERMANENT;
-		filter.flagmask |= IFA_F_PERMANENT;
+		arg = "-permanent";
 	} else if (strcmp(arg, "primary") == 0) {
-		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;
+		arg = "-secondary";
+	}
 
-			filter.flags &= ifa_flag_names[i].value;
-			filter.flagmask |= ifa_flag_names[i].value;
-			return 0;
-		}
+	if (*arg == '-') {
+		inv = true;
+		++arg;
+	}
 
-		return -1;
-	} else {
-		for (i = 0; i < ARRAY_SIZE(ifa_flag_names); i++) {
-			if (strcmp(arg, ifa_flag_names[i].name))
-				continue;
+	for (i = 0; i < ARRAY_SIZE(ifa_flag_names); i++) {
+		if (strcmp(arg, ifa_flag_names[i].name))
+			continue;
+
+		if (inv) {
+			filter.flags &= ~ifa_flag_names[i].value;
+			filter.flagmask |= ifa_flag_names[i].value;
+		} else {
 			filter.flags |= ifa_flag_names[i].value;
 			filter.flagmask |= ifa_flag_names[i].value;
-			return 0;
 		}
-		return -1;
+		return 0;
 	}
-
-	return 0;
+	return -1;
 }
 
 static int ifa_label_match_rta(int ifindex, const struct rtattr *rta)

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

[Phil Sutter]

Hi Stephen,

On Wed, Nov 14, 2018 at 11:29:03AM -0800, Stephen Hemminger wrote:
[...]
> I was thinking something like this which simplifies the logic.
> 
> diff --git a/ip/ipaddress.c b/ip/ipaddress.c
> index cd8cc76a3473..3f1510383071 100644
> --- a/ip/ipaddress.c
> +++ b/ip/ipaddress.c
> @@ -1212,37 +1212,34 @@ static void print_ifa_flags(FILE *fp, const struct ifaddrmsg *ifa,
>  static int get_filter(const char *arg)
>  {
>  	unsigned int i;
> +	bool inv = false;
>  
>  	/* Special cases */
>  	if (strcmp(arg, "dynamic") == 0) {
> -		filter.flags &= ~IFA_F_PERMANENT;
> -		filter.flagmask |= IFA_F_PERMANENT;
> +		arg = "-permanent";

I like this idea, also because it's much easier to get how 'dynamic' and
'primary' are special. I'll respin then.

Thanks, Phil