> On 3/21/17 11:53 AM, Toomas Soome wrote: > > > >> On 21. m?rts 2017, at 17:15, Ian Lepore <i...@freebsd.org> wrote: > >> > >> On Tue, 2017-03-21 at 15:35 +0300, Slawa Olhovchenkov wrote: > >>> On Mon, Mar 20, 2017 at 10:20:17PM +0000, Toomas Soome wrote: > >>> > >>>> > >>>> Author: tsoome > >>>> Date: Mon Mar 20 22:20:17 2017 > >>>> New Revision: 315653 > >>>> URL: https://svnweb.freebsd.org/changeset/base/315653 > >>>> > >>>> Log: > >>>> loader: verify the value from dhcp.interface-mtu and use snprintf > >>>> to set mtu > >>>> > >>>> Since the uset can set dhcp.interface-mtu, we need to try to > >>>> validate the > >>>> value. So we verify if the conversion to int is successful and we > >>>> will not > >>>> allow to set value greater than max IPv4 packet size. > >>>> > >>>> + tmp > USHRT_MAX) { > >>>> + printf("%s: bad value: > >>>> \"%s\", " > >>>> + "ignoring\n", > >>>> + "dhcp.interface-mtu", > >>>> val); > >>> === > >>> USHRT_MAX Maximum value for an object of type unsigned short > >>> int > >>> 65535 (216-1) or greater* > >>> > >>> * the actual value depends on the particular system and library > >>> implementation, but shall reflect the limits of these types in the > >>> target platform. > >>> === > >>> > >>> I mean IF_MAXMTU more correct. > >>> > >> > >> The context here is libstand; because it is standalone by design, the > >> code doesn't have access to IF_MAXMTU or other kernel/userland > >> constants. There is also no question that a short is 16 bits or that > >> USHRT_MAX will be anything other than 65535 in that environment. If > >> some platform did appear that had a different-sized short by default, > >> we would add whatever flags are necessary to force it back to 16 bits > >> in src/share/mk/bsd.stand.mk. > >> > > > > > > Also note the ?upper? value is entirely fictional - we felt we need > > to pick some ?sane? default, with current (common 1Gb/s) ethernet hardware > > you will be in trouble long before reaching that value;) > > All the world is not an VAX, nor is every network Ethernet. > > HIPPI, not that you see much of it nowadays, had a MTU for > switched networks of 65280 (64K - 216 bytes of overhead). > Using USHRT_MAX is exactly the right thing here.
USHRT_MAX _could_ easily be >16 bits in the not too distant future, though this code doesnt seem to be able to include the proper header to get to a proper define it should probably just localally #define it to be 65535 to avoid the breakage 10 years from now. > -Kurt -- Rod Grimes rgri...@freebsd.org _______________________________________________ svn-src-head@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
