Re: inet_pton problem

[Paul Schutte <sjpschutte@gmail.com>]

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Hi Rich,

Unfortunately this is not the complete fix.

Haproxy still complains about invalid networks.

The following seems to fix the problem without adding too much bloat:

--- a/musl/src/network/inet_pton.c
+++ b/musl/src/network/inet_pton.c
@@ -14,11 +14,11 @@
        return -1;
 }

-int inet_pton(int af, const char *restrict s, void *restrict a0)
+int inet_pton(int af, const char *restrict s0, void *restrict a0)
 {
        uint16_t ip[8];
        unsigned char *a = a0;
-       const char *z;
+       const char *z,*s = s0;
        unsigned long x;
        int i, j, v, d, brk=-1, need_v4=0;

@@ -73,6 +73,10 @@
                *a++ = ip[j]>>8;
                *a++ = ip[j];
        }
+
+       /* There must have been valid IPv6 preceding IPv4 dotted-quad */
+       if (s==s0) return 0;
+
        if (need_v4 && inet_pton(AF_INET, (void *)s, a-4) <= 0) return 0;
        return 1;
 }



Regards
Paul



On Sun, Oct 20, 2013 at 11:50 AM, Paul Schutte <sjpschutte@gmail.com> wrote:

> Hi Rich,
>
> I agree with you, especially about the bloat part.
>
> They (haproxy) actually use this function to determine whether the address
> they have is a valid IPv6 address.
> They pass in either a valid IPv4 or IPv6 address and then rely on this
> function to determine which they have (assuming a return value of 0).
>
> After reading the spec more carefully I realise that -1 should be returned
> only when the address family is not AF_INET or AF_INET6.
>
> By changing the return value in the IPv6 code to 0 instead of -1, we could
> get the correct behaviour without any extra code.
>
> Here is a patch to try and save you a bit of work:
>
> --- a/musl/src/network/inet_pton.c
> +++ b/musl/src/network/inet_pton.c
> @@ -46,24 +46,24 @@
>                         if (!s[1]) break;
>                         continue;
>                 }
> -               if (hexval(s[0])<0) return -1;
> +               if (hexval(s[0])<0) return 0;
>                 while (s[0]=='0' && s[1]=='0') s++;
>                 for (v=j=0; j<5 && (d=hexval(s[j]))>=0; j++)
>                         v=16*v+d;
> -               if (v > 65535) return -1;
> +               if (v > 65535) return 0;
>                 ip[i] = v;
>                 if (!s[j]) {
> -                       if (brk<0 && i!=7) return -1;
> +                       if (brk<0 && i!=7) return 0;
>                         break;
>                 }
>                 if (i<7) {
>                         if (s[j]==':') continue;
> -                       if (s[j]!='.') return -1;
> +                       if (s[j]!='.') return 0;
>                         need_v4=1;
>                         i++;
>                         break;
>                 }
> -               return -1;
> +               return 0;
>         }
>         if (brk>=0) {
>                 memmove(ip+brk+7-i, ip+brk, 2*(i+1-brk));
> @@ -73,6 +73,6 @@
>                 *a++ = ip[j]>>8;
>                 *a++ = ip[j];
>         }
> -       if (need_v4 &&inet_pton(AF_INET, (void *)s, a-4) <= 0) return -1;
> +       if (need_v4 &&inet_pton(AF_INET, (void *)s, a-4) <= 0) return 0;
>         return 1;
>  }
>
> Regards
> Paul
>
>
>
> On Sun, Oct 20, 2013 at 4:22 AM, Rich Felker <dalias@aerifal.cx> wrote:
>
>> On Sat, Oct 19, 2013 at 10:57:00PM +0200, Paul Schutte wrote:
>> > Hi,
>> >
>> > I came across this and believe it is a bug.
>> >
>> > I have found that when you set str to an IPv4 addr of the from
>> > "xxx.xxx.xxx.xxx' while the address family is AF_INET6, then instead of
>> > returning a 0 to indicate an invalid IPv6 string, it is converted to
>> > gibberish.
>>
>> From what I can tell, it's not converted to gibberish; instead, it's
>> wrongly returning an error (-1) instead of a result indicating an
>> invalid input string (0). One could argue that it's a programming
>> error not to check this, but inet_pton should not have any reason to
>> return -1 if the first argument (af) is valid, so one could also argue
>> that such checks would be extraneous bloat.
>>
>> > inet_pton(AF_INET6, "192.168.1.1', &sa) should return 0 if I understand
>> the
>> > specification correctly.
>>
>> Agreed.
>>
>> Rich
>>
>
>

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