[radvd-devel-l] string type in radvd scanner.l

Mark Smith radvd at 02a76c927861ca7413a122f2a73a0d37.nosense.org
Thu May 5 18:13:50 EDT 2011

On Thu, 5 May 2011 10:30:00 -0700
Reuben Hawkins <reubenhwk at gmail.com> wrote:

> Hi All,
> This is what the radvd scanner considers a string (for interface names
> and dnssl)...
> string          [a-zA-Z0-9`~!@#$%\^&*()_\-+=:\[\]<>,\.?\\]{1,255}
> Does it really need to be so complex?  This change was added October
> 14, 2008 with the commit message... "Accept virtually any interface
> name (up to 15 chars) instead of forcing a specific naming
> convention." and it was defined as...
> string    [a-z]([a-z:._-]|{digit})*([:.]{digit}+)?
> As it is now, scanner.o is 369K (on my machine), but with the older
> version of string, scanner.o is 68K.  The rest of radvd is only 157K.
> The more complex version of string increases the size of radvd by a
> factor of three.  Is this really needed?  Can somebody come up with
> something simpler which will provide a decent trade-off?

What would the risk be of accepting any string at all, and then passing
it to the system routines that match interface names? Isn't the use of
interface names an exact match lookup, so either the string supplied
either matches a host interface name or doesn't, and therefore a
interface name with any incorrect characters (regardless of what they
are) would fail and understandably fail?

(I too have been wondering why scanner.o is so large.)


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