[Libvirt-cim] [PATCH] Improve random MAC generator

[Richard Maciel]

+1

Kaitlin Rupert wrote:
> # HG changeset patch
> # User Kaitlin Rupert <karupert at us.ibm.com>
> # Date 1237266354 25200
> # Node ID 69b7af00d9da92ce169d915bb6b17c493fe0b021
> # Parent  160e1a86d82e8ed930e3006098f2af8b230c9834
> Improve random MAC generator
> 
> Use microseconds since the epoch instead of seconds.  When defining a guest
> with multiple net devices specified (in which none of them have a MAC supplied),
> it's possible for _net_rand_mac() to be called in rapid succession.
> 
> Also, initialize s - the seed value passed to rand_r().
> 
> Signed-off-by: Kaitlin Rupert <karupert at us.ibm.com>
> 
> diff -r 160e1a86d82e -r 69b7af00d9da src/Virt_VirtualSystemManagementService.c
> --- a/src/Virt_VirtualSystemManagementService.c	Mon Mar 16 13:55:02 2009 -0700
> +++ b/src/Virt_VirtualSystemManagementService.c	Mon Mar 16 22:05:54 2009 -0700
> @@ -25,6 +25,7 @@
>  #include <stdbool.h>
>  #include <inttypes.h>
>  #include <time.h>
> +#include <sys/time.h>
>  #include <libvirt/libvirt.h>
> 
>  #include "cmpidt.h"
> @@ -383,8 +384,14 @@
>          const char *_mac = NULL;
>          CMPIString *str = NULL;
>          CMPIStatus status;
> +        struct timeval curr_time;
> 
> -        srand(time(NULL));
> +        ret = gettimeofday(&curr_time, NULL);
> +        if (ret != 0)
> +                goto out;
> +
> +        srand(curr_time.tv_usec);
> +        s = curr_time.tv_usec;
>          r = rand_r(&s);
> 
>          ret = asprintf(&mac,
> 
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-- 
Richard Maciel, MSc
IBM Linux Technology Center
rmaciel at linux.vnet.ibm.com