[U-Boot] [PATCH] lib: net_utils: make string_to_ip stricter

[Chris Packham]

On Mon, Dec 26, 2016 at 6:23 PM, Simon Glass <sjg at chromium.org> wrote:
> Hi Chris,
>
> On 20 December 2016 at 11:01, Chris Packham <judge.packham at gmail.com> wrote:
>> Previously values greater than 255 were implicitly truncated. Add some
>> stricter checking to reject addresses with components >255.
>>
>> With the input "1234192.168.1.1" the old behaviour would truncate the
>> address to 192.168.1.1. New behaviour rejects the string outright and
>> returns 0.0.0.0, which for the purposes of IP addresses can be
>> considered an error.
>>
>> Signed-off-by: Chris Packham <judge.packham at gmail.com>
>> ---
>> This was part of my long running IPv6 patchset (which I promise I'll get
>> back to someday). But I feel this stands on it's own merits.
>>
>>  lib/net_utils.c | 11 ++++++++---
>>  1 file changed, 8 insertions(+), 3 deletions(-)
>>
>> diff --git a/lib/net_utils.c b/lib/net_utils.c
>> index cfae84275241..f148b8a70a7d 100644
>> --- a/lib/net_utils.c
>> +++ b/lib/net_utils.c
>> @@ -24,11 +24,16 @@ struct in_addr string_to_ip(const char *s)
>>
>>         for (addr.s_addr = 0, i = 0; i < 4; ++i) {
>>                 ulong val = s ? simple_strtoul(s, &e, 10) : 0;
>> +               if (val > 255) {
>> +                       addr.s_addr = 0;
>> +                       return addr;
>> +               }
>>                 addr.s_addr <<= 8;
>>                 addr.s_addr |= (val & 0xFF);
>> -               if (s) {
>> -                       s = (*e) ? e+1 : e;
>> -               }
>> +               if (*e == '.')
>> +                       s = e + 1;
>> +               else
>> +                       break;
>
> This change seems to be unrelated. Should it be a separate commit?

I should at least mention it's purpose in the commit message. It
ensures that '.' is used as a separator and not some other arbitrary
ascii character.

> Also, what happens with '192.168.4' with this change?
>

Good point. I think it would be parsed as 0.192.168.4 which is clearly
wrong. The else should probably set s_addr to 0 to flag the error.

>>         }
>>
>>         addr.s_addr = htonl(addr.s_addr);
>> --
>> 2.11.0.24.ge6920cf
>>
>
> Regards,
> Simon