DNS endianness

DNS endianness

[Andrei Borzenkov]

This does not sound right ...

static grub_err_t
recv_hook (grub_net_udp_socket_t sock __attribute__ ((unused)),
           struct grub_net_buff *nb,
           void *data_)
{
...
  head = (struct dns_header *) nb->data;
...
  for (i = 0; i < grub_cpu_to_be16 (head->qdcount); i++)
    {

We sure want to convert *to* cpu, not *from* cpu here? Same in all
other places in this function.

Do I miss something obvious here? Or how about patch below?

diff --git a/grub-core/net/dns.c b/grub-core/net/dns.c
index 0b771fb..9d0c8fc 100644
--- a/grub-core/net/dns.c
+++ b/grub-core/net/dns.c
@@ -262,7 +262,7 @@ recv_hook (grub_net_udp_socket_t sock __attribute__ ((unused)),
       grub_netbuff_free (nb);
       return GRUB_ERR_NONE;
     }
-  for (i = 0; i < grub_cpu_to_be16 (head->qdcount); i++)
+  for (i = 0; i < grub_be_to_cpu16 (head->qdcount); i++)
     {
       if (ptr >= nb->tail)
 	{
@@ -277,7 +277,7 @@ recv_hook (grub_net_udp_socket_t sock __attribute__ ((unused)),
       ptr += 4;
     }
   *data->addresses = grub_malloc (sizeof ((*data->addresses)[0])
-				 * grub_cpu_to_be16 (head->ancount));
+				 * grub_be_to_cpu16 (head->ancount));
   if (!*data->addresses)
     {
       grub_errno = GRUB_ERR_NONE;
@@ -286,7 +286,7 @@ recv_hook (grub_net_udp_socket_t sock __attribute__ ((unused)),
     }
   reparse_ptr = ptr;
  reparse:
-  for (i = 0, ptr = reparse_ptr; i < grub_cpu_to_be16 (head->ancount); i++)
+  for (i = 0, ptr = reparse_ptr; i < grub_be_to_cpu16 (head->ancount); i++)
     {
       int ignored = 0;
       grub_uint8_t class;

Re: DNS endianness

[Colin Watson]

On Mon, Sep 22, 2014 at 08:53:25PM +0400, Andrei Borzenkov wrote:
> This does not sound right ...
> 
> static grub_err_t
> recv_hook (grub_net_udp_socket_t sock __attribute__ ((unused)),
>            struct grub_net_buff *nb,
>            void *data_)
> {
> ...
>   head = (struct dns_header *) nb->data;
> ...
>   for (i = 0; i < grub_cpu_to_be16 (head->qdcount); i++)
>     {
> 
> We sure want to convert *to* cpu, not *from* cpu here? Same in all
> other places in this function.

The operations are precisely synonymous in all cases, so you should just
use whichever spelling is clearest.

-- 
Colin Watson                                       [cjwatson@ubuntu.com]

Re: DNS endianness

[Vladimir 'φ-coder/phcoder' Serbinenko]

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It's purely code aesthetics but go ahead.
Andrei Borzenkov wrote:
> This does not sound right ...
> 
> static grub_err_t
> recv_hook (grub_net_udp_socket_t sock __attribute__ ((unused)),
>            struct grub_net_buff *nb,
>            void *data_)
> {
> ...
>   head = (struct dns_header *) nb->data;
> ...
>   for (i = 0; i < grub_cpu_to_be16 (head->qdcount); i++)
>     {
> 
> We sure want to convert *to* cpu, not *from* cpu here? Same in all
> other places in this function.
> 
> Do I miss something obvious here? Or how about patch below?
> 
> diff --git a/grub-core/net/dns.c b/grub-core/net/dns.c
> index 0b771fb..9d0c8fc 100644
> --- a/grub-core/net/dns.c
> +++ b/grub-core/net/dns.c
> @@ -262,7 +262,7 @@ recv_hook (grub_net_udp_socket_t sock __attribute__ ((unused)),
>        grub_netbuff_free (nb);
>        return GRUB_ERR_NONE;
>      }
> -  for (i = 0; i < grub_cpu_to_be16 (head->qdcount); i++)
> +  for (i = 0; i < grub_be_to_cpu16 (head->qdcount); i++)
>      {
>        if (ptr >= nb->tail)
>  	{
> @@ -277,7 +277,7 @@ recv_hook (grub_net_udp_socket_t sock __attribute__ ((unused)),
>        ptr += 4;
>      }
>    *data->addresses = grub_malloc (sizeof ((*data->addresses)[0])
> -				 * grub_cpu_to_be16 (head->ancount));
> +				 * grub_be_to_cpu16 (head->ancount));
>    if (!*data->addresses)
>      {
>        grub_errno = GRUB_ERR_NONE;
> @@ -286,7 +286,7 @@ recv_hook (grub_net_udp_socket_t sock __attribute__ ((unused)),
>      }
>    reparse_ptr = ptr;
>   reparse:
> -  for (i = 0, ptr = reparse_ptr; i < grub_cpu_to_be16 (head->ancount); i++)
> +  for (i = 0, ptr = reparse_ptr; i < grub_be_to_cpu16 (head->ancount); i++)
>      {
>        int ignored = 0;
>        grub_uint8_t class;
> 
> _______________________________________________
> Grub-devel mailing list
> Grub-devel@gnu.org
> https://lists.gnu.org/mailman/listinfo/grub-devel
> 



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