Re: [libvirt] [PATCH] Blank out invalid interface names with escaped letters etc.

["Daniel P. Berrange" <berrange@xxxxxxxxxx>]

On Wed, Mar 31, 2010 at 08:50:45AM -0400, Stefan Berger wrote:
> Hunt interface names through a regular expression matcher to check whether they only contain valid characters.
> Valid characters in this code are currently a-z,A-Z,0-9, and '_'.
> 
> Signed-off-by: Stefan Berger <stefanb@xxxxxxxxxx>
> 
> ---
>  src/conf/domain_conf.c |   22 +++++++++++++++++++++-
>  1 file changed, 21 insertions(+), 1 deletion(-)
> 
> Index: libvirt-acl/src/conf/domain_conf.c
> ===================================================================
> --- libvirt-acl.orig/src/conf/domain_conf.c
> +++ libvirt-acl/src/conf/domain_conf.c
> @@ -28,6 +28,7 @@
>  #include <unistd.h>
>  #include <fcntl.h>
>  #include <dirent.h>
> +#include <regex.h>
>  
>  #include "virterror_internal.h"
>  #include "datatypes.h"
> @@ -1776,6 +1777,23 @@ cleanup:
>  }
>  
>  
> +static bool
> +isValidIfname(const char *ifname) {
> +    int rc = 1;
> +    regex_t regex_ifname;
> +
> +    if (regcomp(&regex_ifname, "^[a-zA-Z0-9_]+$",
> +                REG_NOSUB|REG_EXTENDED) != 0)
> +        return 0;
> +
> +    if (regexec(&regex_ifname, ifname, 0, NULL, 0) != 0)
> +        rc = 0;
> +
> +    regfree(&regex_ifname);
> +    return rc;
> +}

There's a slightly simpler way you can do this using strspn avoiding the
regex engine

 #define VALID_IFNAME_CHARS
  "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-_"

 rc = strspn(ifname, VALID_IFNAME_CHARS) != strlen (value);



Daniel
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