Date: Wed, 23 Nov 2011 06:53:05 -0800 From: Qing Li <qingli@freebsd.org> To: Gleb Smirnoff <glebius@freebsd.org> Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org Subject: Re: svn commit: r227791 - head/sys/netinet Message-ID: <CAGnGRdKsKMT%2BDsuj5aXbso8VCpkPiEJz-H8qsheJtPNpK13tvA@mail.gmail.com> In-Reply-To: <20111122154312.GL96616@FreeBSD.org> References: <201111211410.pALEAD9B046139@svn.freebsd.org> <CAGnGRdLpWwTkfjirBYe7x-1TVOMtHiRJNX4dM-iQXwQgP3mCVQ@mail.gmail.com> <20111121195439.GE96616@FreeBSD.org> <CAGnGRdL%2BTBG7O55FnfgTmLBE8=cdZPy%2BcOdJZNgbB9P=BCdMww@mail.gmail.com> <20111122154312.GL96616@FreeBSD.org>
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> > =A0first I'd like to notice that we are speaking about obsoleted interfac= es. > Yup, that's why you don't see me commenting on your other commits around ia_netmask stuff, do you ? <snip> > > Back to your comments: > > I have made a test case that proves, that usage of deleted address isn't > prevented when it is removed, but loopback route still exists. > > The test is the following run a race between this program: > > =A0 =A0 =A0 =A0struct ifreq ifr; > =A0 =A0 =A0 =A0int s; > > =A0 =A0 =A0 =A0bzero(&ifr, sizeof(struct ifreq)); > > =A0 =A0 =A0 =A0strncpy(ifr.ifr_name, "igb1", sizeof ifr.ifr_name); > =A0 =A0 =A0 =A0ifr.ifr_addr.sa_family =3D AF_INET; > =A0 =A0 =A0 =A0ifr.ifr_addr.sa_len =3D sizeof(struct sockaddr_in); > =A0 =A0 =A0 =A0((struct sockaddr_in *)&ifr.ifr_addr)->sin_addr.s_addr =3D= inet_addr("10.0.0.1"); > > =A0 =A0 =A0 =A0s =3D socket(AF_INET, SOCK_DGRAM, 0); > > =A0 =A0 =A0 =A0for (;;) > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0ioctl(s, SIOCSIFADDR, &ifr); > > And this script: > > =A0 =A0 =A0 =A0while (true); do nc -z 10.0.0.1 22 || echo Fail; done > I am not sure if this test scenario is valid. The loopback route is wiped at line #853 and then quickly inserted back at line #936 because you are SIOCSIFADDR the same address over and over again. <snip> > > Application writers don't know this in-kernel things. They usually write = code > this way: > > =A0 =A0 =A0 =A0if (ioctl(foo) < 0) { > =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0/* fatal error: can't configure address! *= / > =A0 =A0 =A0 =A0} > > And this is correct way. Look into this from viewpoint of say quagga deve= loper. > One doesn't need to know about this tricks in FreeBSD kernel. > Yes, you have a good point there and I agree completely. --Qing
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