Hi Mario,

On ke, 2014-07-09 at 16:52 +0200, Mario Schuknecht wrote:
> 4-byte memory access works only when pointer is 4-byte aligned. Use memcpy
> function, since 4-byte pointer alignment is not guaranteed. The same applies
> to 2-byte memory access.

What hardware do you see this issue? At least the Intel and ARM devices
I have used work just fine as is.

I would prefer the use << operator instead of memcpy here. See usage
examples in dnsproxy.c for details.

> 
> Signed-off-by: Mario Schuknecht <[email protected]>
> ---
>  src/dnsproxy.c | 20 ++++++++++----------
>  1 file changed, 10 insertions(+), 10 deletions(-)
> 
> diff --git a/src/dnsproxy.c b/src/dnsproxy.c
> index 3e32b5a..57f28fa 100644
> --- a/src/dnsproxy.c
> +++ b/src/dnsproxy.c
> @@ -356,8 +356,8 @@ static int dns_name_length(unsigned char *buf)
>  static void update_cached_ttl(unsigned char *buf, int len, int new_ttl)
>  {
>       unsigned char *c;
> -     uint32_t *i;
> -     uint16_t *w;
> +     uint32_t i;
> +     uint16_t w;
>       int l;
>  
>       /* skip the header */
> @@ -387,17 +387,17 @@ static void update_cached_ttl(unsigned char *buf, int 
> len, int new_ttl)
>                       break;
>  
>               /* now the 4 byte TTL field */
> -             i = (uint32_t *)c;
> -             *i = htonl(new_ttl);
> +             i = htonl(new_ttl);
> +             memcpy(c, &i, 4);
>               c += 4;
>               len -= 4;
>               if (len < 0)
>                       break;
>  
>               /* now the 2 byte rdlen field */
> -             w = (uint16_t *)c;
> -             c += ntohs(*w) + 2;
> -             len -= ntohs(*w) + 2;
> +             memcpy(&w, c, 2);
> +             c += ntohs(w) + 2;
> +             len -= ntohs(w) + 2;
>       }
>  }
>  
> @@ -1344,7 +1344,7 @@ static void cache_refresh(void)
>  static int reply_query_type(unsigned char *msg, int len)
>  {
>       unsigned char *c;
> -     uint16_t *w;
> +     uint16_t w;
>       int l;
>       int type;
>  
> @@ -1358,8 +1358,8 @@ static int reply_query_type(unsigned char *msg, int len)
>       /* now the query, which is a name and 2 16 bit words */
>       l = dns_name_length(c) + 1;
>       c += l;
> -     w = (uint16_t *) c;
> -     type = ntohs(*w);
> +     memcpy(&w, c, 2);
> +     type = ntohs(w);
>  
>       return type;
>  }


Cheers,
Jukka


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