Re: Unresolved external -- read_random( )

[Matt Jerdonek <maj1224 at yahoo dot com>]

Andrew,

Thanks for looking at the patch.

I agree that the casts are ugly.  However, I initially
found this bug in porting IPSec to eCos.  While the
current IP code does not ask for a
multiple-of-4-length random number, I don't know that
the IPSec code will always ask for a
multiple-of-4-length random number.

I took this code from FreeBSD, so I'm assuming that it
was written as it is for a reason.

-- Matt


--- Andrew Lunn <andrew@lunn.ch> wrote:
> On Mon, Sep 08, 2003 at 09:27:15AM -0700, Matt
> Jerdonek wrote:
> > Index: support.c
> >
>
===================================================================
> > RCS file:
> >
>
/cvs/ecos/ecos-opt/net/net/bsd_tcpip/current/src/ecos/support.c,v
> > retrieving revision 1.9
> > diff -r1.9 support.c
> > 564a565,582
> > > int
> > > read_random(void *buf, int count)
> > > {
> > >       int randval;
> > >       int size, i;
> > >
> > >       /* Fill buf[] with random output */
> > >       for (i = 0; i < count; i+=
> (int)sizeof(int)) {
> > >               randval = arc4random();
> > >               size = (count - i) <
> (int)sizeof(int)
> > >                   ? (count - i)
> > >                   : sizeof(int);
> > >               memcpy(&((char *)buf)[i],
> &randval,
> > (size_t)size);
> > >       }
> > >
> > >       return count;
> > > }
> 
> Looks a bit ugly to me with all these casts. My
> preferred solution is:
> 
> Index: net/bsd_tcpip/current//ChangeLog
>
===================================================================
> RCS file:
>
/cvs/ecos/ecos-opt/net/net/bsd_tcpip/current/ChangeLog,v
> retrieving revision 1.31
> diff -u -r1.31 ChangeLog
> --- net/bsd_tcpip/current//ChangeLog	30 Jul 2003
> 07:42:31 -0000	1.31
> +++ net/bsd_tcpip/current//ChangeLog	8 Sep 2003
> 17:24:22 -0000
> @@ -1,3 +1,9 @@
> +2003-09-08  Andrew Lunn  <andrew.lunn@ascom.ch>
> +
> +	* src/ecos/support.c (read_random): New function
> which is needed
> +	when CYGSEM_NET_RANDOMID is enabled.
> +	* include/sys/param.h: Prototype for new function.
> +
>  2003-07-25  Andrew Lunn  <andrew.lunn@ascom.ch>
>  
>  	* include/netinet/icmp_var.h 
> Index: net/bsd_tcpip/current//include/sys/param.h
>
===================================================================
> RCS file:
>
/cvs/ecos/ecos-opt/net/net/bsd_tcpip/current/include/sys/param.h,v
> retrieving revision 1.4
> diff -u -r1.4 param.h
> --- net/bsd_tcpip/current//include/sys/param.h	30
> Jul 2003 07:42:32 -0000	
> 1.4
> +++ net/bsd_tcpip/current//include/sys/param.h	8 Sep
> 2003 17:24:25 -0000
> @@ -877,6 +877,7 @@
>  extern void get_mono_time(void);
>  extern int arc4random(void);
>  extern void get_random_bytes(void *buf, size_t
> len);
> +extern void read_random(void *buf, size_t len);
>  extern void read_random_unlimited(void *buf, size_t
> len);
>  extern void *hashinit(int elements, void *type,
> u_long *hashmask);
>  
> Index: net/bsd_tcpip/current//src/ecos/support.c
>
===================================================================
> RCS file:
>
/cvs/ecos/ecos-opt/net/net/bsd_tcpip/current/src/ecos/support.c,v
> retrieving revision 1.9
> diff -u -r1.9 support.c
> --- net/bsd_tcpip/current//src/ecos/support.c	23 Jun
> 2003 09:45:11 -0000	
> 1.9
> +++ net/bsd_tcpip/current//src/ecos/support.c	8 Sep
> 2003 17:24:28 -0000
> @@ -562,6 +562,13 @@
>      get_random_bytes(buf, len);
>  }
>  
> +void read_random(void *buf, size_t len) 
> +{
> +    CYG_ASSERT(0 == (len & ~3), "Only multiple of
> words allowed");
> +  
> +    get_random_bytes(buf, len);
> +}
> +
>  void 
>  microtime(struct timeval *tp)
>  {
> 
> This compiles cleanly, but i've not run it. I hope i
> got that assert
> correct! I checked where read_random is called from
> and len is always
> 4. I just put the assert there for the case somebody
> adds new code
> which passed a funny value for len which we don't
> deal with.


__________________________________
Do you Yahoo!?
Yahoo! SiteBuilder - Free, easy-to-use web site design software
http://sitebuilder.yahoo.com