[PATCH nft v2] datatype: Display pre-defined inet_service values in host byte order

[PATCH nft v2] datatype: Display pre-defined inet_service values in host byte order

[Elise Lennion]

nft describe displays, to the user, which values are available for a selector,
then the values should be in host byte order.

Reported-by: Pablo Neira Ayuso <pablo@netfilter.org>
Fixes: ccc5da470e76 ("datatype: Replace getnameinfo() by internal lookup table")
Signed-off-by: Elise Lennion <elise.lennion@gmail.com>
---

 v2: Created a function to convert different types and number of bytes

 include/datatype.h |  3 ++-
 src/datatype.c     | 27 ++++++++++++++++++++++++---
 src/expression.c   |  3 ++-
 3 files changed, 28 insertions(+), 5 deletions(-)

diff --git a/include/datatype.h b/include/datatype.h
index d4fe817..a7db1df 100644
--- a/include/datatype.h
+++ b/include/datatype.h
@@ -191,7 +191,8 @@ extern struct error_record *symbolic_constant_parse(const struct expr *sym,
 extern void symbolic_constant_print(const struct symbol_table *tbl,
 				    const struct expr *expr, bool quotes);
 extern void symbol_table_print(const struct symbol_table *tbl,
-			       const struct datatype *dtype);
+			       const struct datatype *dtype,
+			       enum byteorder byteorder);
 
 extern struct symbol_table *rt_symbol_table_init(const char *filename);
 extern void rt_symbol_table_free(struct symbol_table *tbl);
diff --git a/src/datatype.c b/src/datatype.c
index b5d73bc..c884171 100644
--- a/src/datatype.c
+++ b/src/datatype.c
@@ -180,15 +180,36 @@ void symbolic_constant_print(const struct symbol_table *tbl,
 		printf("%s", s->identifier);
 }
 
+static void big_to_host_byteorder(void *value, const unsigned int nbytes)
+{
+	unsigned char *p = value;
+	unsigned int i;
+
+	for (i = 0; i < nbytes / 2; i++) {
+		p[i] ^= p[nbytes - 1 - i];
+		p[nbytes - 1 - i] ^= p[i];
+		p[i] ^= p[nbytes - 1 - i];
+	}
+}
+
 void symbol_table_print(const struct symbol_table *tbl,
-			const struct datatype *dtype)
+			const struct datatype *dtype,
+			enum byteorder byteorder)
 {
 	const struct symbolic_constant *s;
 	unsigned int size = 2 * dtype->size / BITS_PER_BYTE;
+	unsigned long int value;
+
+	for (s = tbl->symbols; s->identifier != NULL; s++) {
+		value = s->value;
+
+		if (byteorder == BYTEORDER_BIG_ENDIAN)
+			big_to_host_byteorder(&value,
+					      dtype->size / BITS_PER_BYTE);
 
-	for (s = tbl->symbols; s->identifier != NULL; s++)
 		printf("\t%-30s\t0x%.*" PRIx64 "\n",
-		       s->identifier, size, s->value);
+		       s->identifier, size, value);
+	}
 }
 
 static void invalid_type_print(const struct expr *expr)
diff --git a/src/expression.c b/src/expression.c
index a10af5d..2aada77 100644
--- a/src/expression.c
+++ b/src/expression.c
@@ -115,7 +115,8 @@ void expr_describe(const struct expr *expr)
 
 	if (expr->dtype->sym_tbl != NULL) {
 		printf("\npre-defined symbolic constants:\n");
-		symbol_table_print(expr->dtype->sym_tbl, expr->dtype);
+		symbol_table_print(expr->dtype->sym_tbl, expr->dtype,
+				   expr->byteorder);
 	}
 }
 
-- 
2.7.4

Re: [PATCH nft v2] datatype: Display pre-defined inet_service values in host byte order

[Pablo Neira Ayuso]

Hi Elise,

On Wed, Dec 07, 2016 at 05:03:31PM -0200, Elise Lennion wrote:
> nft describe displays, to the user, which values are available for a selector,
> then the values should be in host byte order.
> 
> Reported-by: Pablo Neira Ayuso <pablo@netfilter.org>
> Fixes: ccc5da470e76 ("datatype: Replace getnameinfo() by internal lookup table")
> Signed-off-by: Elise Lennion <elise.lennion@gmail.com>
> ---
> 
>  v2: Created a function to convert different types and number of bytes
> 
>  include/datatype.h |  3 ++-
>  src/datatype.c     | 27 ++++++++++++++++++++++++---
>  src/expression.c   |  3 ++-
>  3 files changed, 28 insertions(+), 5 deletions(-)
> 
> diff --git a/include/datatype.h b/include/datatype.h
> index d4fe817..a7db1df 100644
> --- a/include/datatype.h
> +++ b/include/datatype.h
> @@ -191,7 +191,8 @@ extern struct error_record *symbolic_constant_parse(const struct expr *sym,
>  extern void symbolic_constant_print(const struct symbol_table *tbl,
>  				    const struct expr *expr, bool quotes);
>  extern void symbol_table_print(const struct symbol_table *tbl,
> -			       const struct datatype *dtype);
> +			       const struct datatype *dtype,
> +			       enum byteorder byteorder);
>  
>  extern struct symbol_table *rt_symbol_table_init(const char *filename);
>  extern void rt_symbol_table_free(struct symbol_table *tbl);
> diff --git a/src/datatype.c b/src/datatype.c
> index b5d73bc..c884171 100644
> --- a/src/datatype.c
> +++ b/src/datatype.c
> @@ -180,15 +180,36 @@ void symbolic_constant_print(const struct symbol_table *tbl,
>  		printf("%s", s->identifier);
>  }
>  
> +static void big_to_host_byteorder(void *value, const unsigned int nbytes)
> +{
> +	unsigned char *p = value;
> +	unsigned int i;
> +
> +	for (i = 0; i < nbytes / 2; i++) {
> +		p[i] ^= p[nbytes - 1 - i];
> +		p[nbytes - 1 - i] ^= p[i];
> +		p[i] ^= p[nbytes - 1 - i];
> +	}

Sorry, probably I should have specified a bit more.

I suggest you use libgmp for this, that allows any arbitrary word
size. See mpz_init() to initialize the variable, then
mpz_switch_byteorder() to change byteorder. Then, export it via
mpz_export_data() back to fixed standard datatypes.

libgmp is well documented, please have a look at it.

Thanks.

Re: [PATCH nft v2] datatype: Display pre-defined inet_service values in host byte order

[Elise Lennion]

On Wed, Dec 07, 2016 at 08:25:10PM +0100, Pablo Neira Ayuso wrote:
> Hi Elise,
> 
> On Wed, Dec 07, 2016 at 05:03:31PM -0200, Elise Lennion wrote:
> > nft describe displays, to the user, which values are available for a selector,
> > then the values should be in host byte order.
> > 
> > Reported-by: Pablo Neira Ayuso <pablo@netfilter.org>
> > Fixes: ccc5da470e76 ("datatype: Replace getnameinfo() by internal lookup table")
> > Signed-off-by: Elise Lennion <elise.lennion@gmail.com>
> > ---
> > 
> >  v2: Created a function to convert different types and number of bytes
> > 
> >  include/datatype.h |  3 ++-
> >  src/datatype.c     | 27 ++++++++++++++++++++++++---
> >  src/expression.c   |  3 ++-
> >  3 files changed, 28 insertions(+), 5 deletions(-)
> > 
> > diff --git a/include/datatype.h b/include/datatype.h
> > index d4fe817..a7db1df 100644
> > --- a/include/datatype.h
> > +++ b/include/datatype.h
> > @@ -191,7 +191,8 @@ extern struct error_record *symbolic_constant_parse(const struct expr *sym,
> >  extern void symbolic_constant_print(const struct symbol_table *tbl,
> >  				    const struct expr *expr, bool quotes);
> >  extern void symbol_table_print(const struct symbol_table *tbl,
> > -			       const struct datatype *dtype);
> > +			       const struct datatype *dtype,
> > +			       enum byteorder byteorder);
> >  
> >  extern struct symbol_table *rt_symbol_table_init(const char *filename);
> >  extern void rt_symbol_table_free(struct symbol_table *tbl);
> > diff --git a/src/datatype.c b/src/datatype.c
> > index b5d73bc..c884171 100644
> > --- a/src/datatype.c
> > +++ b/src/datatype.c
> > @@ -180,15 +180,36 @@ void symbolic_constant_print(const struct symbol_table *tbl,
> >  		printf("%s", s->identifier);
> >  }
> >  
> > +static void big_to_host_byteorder(void *value, const unsigned int nbytes)
> > +{
> > +	unsigned char *p = value;
> > +	unsigned int i;
> > +
> > +	for (i = 0; i < nbytes / 2; i++) {
> > +		p[i] ^= p[nbytes - 1 - i];
> > +		p[nbytes - 1 - i] ^= p[i];
> > +		p[i] ^= p[nbytes - 1 - i];
> > +	}
> 
> Sorry, probably I should have specified a bit more.
> 
> I suggest you use libgmp for this, that allows any arbitrary word
> size. See mpz_init() to initialize the variable, then
> mpz_switch_byteorder() to change byteorder. Then, export it via
> mpz_export_data() back to fixed standard datatypes.
> 
> libgmp is well documented, please have a look at it.
> 
> Thanks.

Hello Pablo,

Should I write a function that switches byteorder of different types,
for possible general use, or just use libgmp inside symbol_table_print?

In symbol_table_print the converted values have a specific type, so,
something similar to the following is enough, right?

...

 if (byteorder == BYTEORDER_BIG_ENDIAN) {
 	mpz_init_set_ui(v, value);
 	mpz_switch_byteorder(v, nbytes);
 	mpz_export_data(&value, v, BYTEORDER_HOST_ENDIAN, nbytes);
 	mpz_clear(v);
 }

...

Thank you,

elise

Re: [PATCH nft v2] datatype: Display pre-defined inet_service values in host byte order

[Pablo Neira Ayuso]

On Thu, Dec 08, 2016 at 03:16:06PM -0200, Elise Lennion wrote:
> On Wed, Dec 07, 2016 at 08:25:10PM +0100, Pablo Neira Ayuso wrote:
> > Hi Elise,
> > 
> > On Wed, Dec 07, 2016 at 05:03:31PM -0200, Elise Lennion wrote:
> > > nft describe displays, to the user, which values are available for a selector,
> > > then the values should be in host byte order.
> > > 
> > > Reported-by: Pablo Neira Ayuso <pablo@netfilter.org>
> > > Fixes: ccc5da470e76 ("datatype: Replace getnameinfo() by internal lookup table")
> > > Signed-off-by: Elise Lennion <elise.lennion@gmail.com>
> > > ---
> > > 
> > >  v2: Created a function to convert different types and number of bytes
> > > 
> > >  include/datatype.h |  3 ++-
> > >  src/datatype.c     | 27 ++++++++++++++++++++++++---
> > >  src/expression.c   |  3 ++-
> > >  3 files changed, 28 insertions(+), 5 deletions(-)
> > > 
> > > diff --git a/include/datatype.h b/include/datatype.h
> > > index d4fe817..a7db1df 100644
> > > --- a/include/datatype.h
> > > +++ b/include/datatype.h
> > > @@ -191,7 +191,8 @@ extern struct error_record *symbolic_constant_parse(const struct expr *sym,
> > >  extern void symbolic_constant_print(const struct symbol_table *tbl,
> > >  				    const struct expr *expr, bool quotes);
> > >  extern void symbol_table_print(const struct symbol_table *tbl,
> > > -			       const struct datatype *dtype);
> > > +			       const struct datatype *dtype,
> > > +			       enum byteorder byteorder);
> > >  
> > >  extern struct symbol_table *rt_symbol_table_init(const char *filename);
> > >  extern void rt_symbol_table_free(struct symbol_table *tbl);
> > > diff --git a/src/datatype.c b/src/datatype.c
> > > index b5d73bc..c884171 100644
> > > --- a/src/datatype.c
> > > +++ b/src/datatype.c
> > > @@ -180,15 +180,36 @@ void symbolic_constant_print(const struct symbol_table *tbl,
> > >  		printf("%s", s->identifier);
> > >  }
> > >  
> > > +static void big_to_host_byteorder(void *value, const unsigned int nbytes)
> > > +{
> > > +	unsigned char *p = value;
> > > +	unsigned int i;
> > > +
> > > +	for (i = 0; i < nbytes / 2; i++) {
> > > +		p[i] ^= p[nbytes - 1 - i];
> > > +		p[nbytes - 1 - i] ^= p[i];
> > > +		p[i] ^= p[nbytes - 1 - i];
> > > +	}
> > 
> > Sorry, probably I should have specified a bit more.
> > 
> > I suggest you use libgmp for this, that allows any arbitrary word
> > size. See mpz_init() to initialize the variable, then
> > mpz_switch_byteorder() to change byteorder. Then, export it via
> > mpz_export_data() back to fixed standard datatypes.
> > 
> > libgmp is well documented, please have a look at it.
> > 
> > Thanks.
> 
> Hello Pablo,
> 
> Should I write a function that switches byteorder of different types,
> for possible general use, or just use libgmp inside symbol_table_print?

A function that you can place under src/gmputil.c would be good, so we
can reuse it later if we have similar needs.

> In symbol_table_print the converted values have a specific type, so,
> something similar to the following is enough, right?
> 
> ...
> 
>  if (byteorder == BYTEORDER_BIG_ENDIAN) {
>  	mpz_init_set_ui(v, value);
>  	mpz_switch_byteorder(v, nbytes);
>  	mpz_export_data(&value, v, BYTEORDER_HOST_ENDIAN, nbytes);
>  	mpz_clear(v);
>  }

Yes, I think that code is on the right track. Thanks.