Date: Fri, 7 Jan 2011 16:38:59 +0300 From: Eygene Ryabinkin <rea@freebsd.org> To: joris dedieu <joris.dedieu@gmail.com> Cc: freebsd-hackers <freebsd-hackers@freebsd.org> Subject: Re: binding non local ip. Message-ID: <I0E3jOweM2JFYO1RRyeZ3hfTJPY@5UW8B3LwPEGInFShts5A7R/S2Yo> In-Reply-To: <AANLkTimJBkTdgs4P=XjHyTCinfCOn0Ku8bEVcR-q=Dzc@mail.gmail.com> References: <AANLkTimJBkTdgs4P=XjHyTCinfCOn0Ku8bEVcR-q=Dzc@mail.gmail.com>
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Fri, Jan 07, 2011 at 01:57:21PM +0100, joris dedieu wrote:
> What do you think about it ?
[...]
> +static int bindany =3D 0; /* 1 allows to bind a non local ip */
> +SYSCTL_INT(_net_inet_ip, OID_AUTO, bindany, CTLFLAG_RW, &bindany, 0,
> + "Allow to bind a non local ip");
On at least 8.x, you will likely want to use VNET_* macros to enable
your new sysctl to be virtualized. Something like this:
{{{
VNET_DEFINE(int, inp_bindany) =3D 0;
SYSCTL_VNET_INT(_net_inet_ip, OID_AUTO, bindany, CTLFLAG_RW,
&VNET_NAME(inp_bindany), 0, "Force INP_BINDANY on all sockets");
}}}
and use VNET(inp_bindany) in subsequent code.
> if ((inp->inp_flags & INP_BINDANY) =3D=3D 0 &&
> - ifa_ifwithaddr_check((struct sockaddr *)sin) =
=3D=3D 0)
> - return (EADDRNOTAVAIL);
> + ifa_ifwithaddr_check((struct sockaddr *)sin) =
=3D=3D 0) {
> + if(bindany > 0)
> + inp->inp_flags |=3D INP_BINDANY;
> + else
> + return (EADDRNOTAVAIL);
> + }
The check is better to be rewritten as
{{{
if (VNET(inp_bindany) > 0)
inp->inp_flags |=3D INP_BINDANY;
else if ((inp->inp_flags & INP_BINDANY) =3D=3D 0 &&
ifa_ifwithaddr_check((struct sockaddr *)sin) =
=3D=3D 0)
return (EADDRNOTAVAIL);
}}}
it will save you two conditionals if bindany is enabled. On the other
hand, if you will set the value of VNET(inp_bindany) to INP_BINDANY
instead of 1, you can even do
{{{
inp->inp_flags |=3D VNET(inp_bindany);
if ((inp->inp_flags & INP_BINDANY) =3D=3D 0 &&
ifa_ifwithaddr_check((struct sockaddr *)sin) =
=3D=3D 0)
return (EADDRNOTAVAIL);
}}}
and this will eliminate one branching instruction at the expense of
memory access and fast logical operation.
--=20
Eygene Ryabinkin ,,,^..^,,,
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