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Date: Sun, 20 Oct 2013 11:50:12 +0200
From: Paul Schutte <sjpschutte@...il.com>
To: musl@...ts.openwall.com
Subject: Re: inet_pton problem
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@...ifal.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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