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using it. Not checking this may have caused the wrong IP address to be used when processing certain IP options (see example below). This also caused the wrong route to be passed to ip_output() when forwarding, but fortunately ip_output() is smart enough to detect this. This example demonstrates the wrong behavior of the Record Route option observed with this bug. Host ``freebsd'' is acting as the gateway for the ``sysv''. 1. On the gateway, we add the route to the destination. The new route will use the primary address of the loopback interface, 127.0.0.1: : freebsd# route add 10.0.0.66 -iface lo0 -reject : add host 10.0.0.66: gateway lo0 2. From the client, we ping the destination. We see the correct replies. Please note that this also causes the relevant route on the ``freebsd'' gateway to be cached in ipforward_rt variable: : sysv# ping -snv 10.0.0.66 : PING 10.0.0.66: 56 data bytes : ICMP Host Unreachable from gateway 192.168.0.115 : ICMP Host Unreachable from gateway 192.168.0.115 : ICMP Host Unreachable from gateway 192.168.0.115 : : ----10.0.0.66 PING Statistics---- : 3 packets transmitted, 0 packets received, 100% packet loss 3. On the gateway, we delete the route to the destination, thus making the destination reachable through the `default' route: : freebsd# route delete 10.0.0.66 : delete host 10.0.0.66 4. From the client, we ping destination again, now with the RR option turned on. The surprise here is the 127.0.0.1 in the first reply. This is caused by the bug in ip_rtaddr() not checking the cached route is still up befor use. The debug code also shows that the wrong (down) route is further passed to ip_output(). The latter detects that the route is down, and replaces the bogus route with the valid one, so we see the correct replies (192.168.0.115) on further probes: : sysv# ping -snRv 10.0.0.66 : PING 10.0.0.66: 56 data bytes : 64 bytes from 10.0.0.66: icmp_seq=0. time=10. ms : IP options: <record route> 127.0.0.1, 10.0.0.65, 10.0.0.66, : 192.168.0.65, 192.168.0.115, 192.168.0.120, : 0.0.0.0(Current), 0.0.0.0, 0.0.0.0 : 64 bytes from 10.0.0.66: icmp_seq=1. time=0. ms : IP options: <record route> 192.168.0.115, 10.0.0.65, 10.0.0.66, : 192.168.0.65, 192.168.0.115, 192.168.0.120, : 0.0.0.0(Current), 0.0.0.0, 0.0.0.0 : 64 bytes from 10.0.0.66: icmp_seq=2. time=0. ms : IP options: <record route> 192.168.0.115, 10.0.0.65, 10.0.0.66, : 192.168.0.65, 192.168.0.115, 192.168.0.120, : 0.0.0.0(Current), 0.0.0.0, 0.0.0.0 : : ----10.0.0.66 PING Statistics---- : 3 packets transmitted, 3 packets received, 0% packet loss : round-trip (ms) min/avg/max = 0/3/10
This is the top level of the FreeBSD source directory. This file was last revised on: $FreeBSD$ For copyright information, please see the file COPYRIGHT in this directory (additional copyright information also exists for some sources in this tree - please see the specific source directories for more information). The Makefile in this directory supports a number of targets for building components (or all) of the FreeBSD source tree, the most commonly used one being ``world'', which rebuilds and installs everything in the FreeBSD system from the source tree except the kernel, the kernel-modules and the contents of /etc. The ``buildkernel'' and ``installkernel'' targets build and install the kernel and the modules (see below). Please see the top of the Makefile in this directory for more information on the standard build targets and compile-time flags. Building a kernel is a somewhat more involved process, documentation for which can be found at: http://www.freebsd.org/handbook/kernelconfig.html And in the config(8) man page. Note: If you want to build and install the kernel with the ``buildkernel'' and ``installkernel'' targets, you have to build world before. More information is available in the handbook. The sample kernel configuration files reside in the sys/i386/conf sub-directory (assuming that you've installed the kernel sources), the file named GENERIC being the one used to build your initial installation kernel. The file NOTES contains entries and documentation for all possible devices, not just those commonly used. It is the successor of the ancient LINT file, but in contrast to LINT, it is not buildable as a kernel but a pure reference and documentation file. Source Roadmap: --------------- bin System/User commands. contrib Packages contributed by 3rd parties. crypto Cryptography stuff (see crypto/README). etc Template files for /etc games Amusements. gnu Various commands and libraries under the GNU Public License. Please see gnu/COPYING* for more information. include System include files. kerberosIV Kerberos package. lib System libraries. libexec System daemons. release Release building Makefile & associated tools. sbin System commands. secure Cryptographic libraries and commands. share Shared resources. sys Kernel sources. tools Utilities for regression testing and miscellaneous tasks. usr.bin User commands. usr.sbin System administration commands. For information on synchronizing your source tree with one or more of the FreeBSD Project's development branches, please see: http://www.freebsd.org/handbook/synching.html