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Module Tests

The following tests verify fundamental functionality of SMCRoute when configure --enable-test. Required tools to be installed and available in $PATH:

  • ip and bridge (iproute2 package, not the BusyBox variants)
  • iptables, for the 1:1 NAT test
  • ping
  • tshark (because tcpdump -w foo.pcap doesn't work in an unshare)
  • valgrind, for the memleak test

Important

One of the tests makes use of iptables, which may not work in an unshare(1), unless you have v1.8.7 or newer that supports the XTABLES_LOCKFILE environment variable. As a workaround you can chmod a+rw /var/run/xtables.lock.

Also, as of Ubuntu 24.04 blocks user namespaces for unprivileged users by default, meaning you need some sysctl magic to set up your system see YoYoGames/GameMaker-Bugs#6015:

sudo sysctl kernel.apparmor_restrict_unprivileged_userns=0

Finally, the GRE test require the ip_gre.ko kernel module to be loaded. If not, the test will be skipped.

Running

To run the tests:

~$ sudo modprobe ip_gre      # if you have sudo capabilities
~$ cd src/smcroute
~/src/smcroute$ ./autogen.sh
~/src/smcroute$ ./configure --enable-test --enable-mrdisc
~/src/smcroute$ make -j9
~/src/smcroute$ make check

Each unit test is standalone. To manually run select tests:

~/src/smcroute$ cd test/
~/src/smcroute/test$ unshare -mrun ./testname.sh

The tools ping and tshark are used to create and listen to multicast streams "routed by" SMCRoute.

Note

These tests must be run in sequence, not in parallel, because they use the same interface names and, most importantly, we may run on a kernel w/o multicast policy routing support!

Topologies

The following test topologies are employed to verify different aspects and use-cases supported by SMCRoute.

Basic

Interfaces a1 and a2 are Linux dummy type interfaces.

                    SMCRoute
             .------ router -----.
            /                     \
MC -----> a1                       a2 ------> MC

Basic Plus

Same as Basic, but with more inbound/output interfaces, useful for testing wildcard interface matching.

                    SMCRoute
             .====== router =====.
            ////               \\\\
 MC ----> a1///                 \\\b1 ------> MC 
 MC ----> a2//                   \\b2 ------> MC 
 MC ----> a3/                     \b3 ------> MC 
 MC ----> a4                       b4 ------> MC

Basic w/ VLANs

Interfaces a1 and a2 are Linux dummy type interfaces with VLAN interfaces created on top. The topology sets up two VLAN interfaces per dummy interface, VID 100 and 110.

                        SMCRoute
              .------.== router ==.------.
             /      /              \      \
MC --> a1.100    a1.110          a2.100  a2.110 --> MC
             \  /                    \  /
              a1                      a2

Bridged w/ VLANs

Two VETH pairs (a1:b1 and a2:b2) are attached to a bridge with VLAN filtering enabled. On top of the bridge two VLAN interfaces are created on which routing takes place.

                   SMCRoute
                .-- router --.
               /              \
             vlan1         vlan2
                  \       /
                   bridge0
MC -----> a1       /     \        a2 -----> MC
           '------'       '------'

Both bridge ports, a1 and a2, are untagged members of each VLAN.

Note

interface a1 and vlan1 are in the same VLAN (VID 1), and interface a2 and vlan2 are in the same VLAN (VID 2).

Isolated Endpoints Bridged w/ VLANs

Like the default bridge, but each endpoint is in an isolated network namespace. This allows setting both IPv4 & IPv6 addresses on all interfaces and using ping6 as emitter instead of requiring nemesis.

                        SMCRoute
                     .-- router --.
                    /              \
  netns: left     vlan1         vlan2    netns: right
 .-------------.       \       /        .-------------.
 |             |        bridge0         |             |
 | MC --> eth0 |        /     \         | eth0 --> MC |
 |            `--------'       '---------'            |
 '-------------'                        '-------------'

Both bridge ports, a1 and a2, are untagged members of each VLAN.

Note

interface a1 and vlan1 are in the same VLAN (VID 1), and interface a2 and vlan2 are in the same VLAN (VID 2).

Isolated

Similar to Basic, but with two VETH pairs with the outer end of each in an isolated network namespace. Purpose is to emulate true end devices.

                        SMCRoute
 netns: left         .-- router --.        netns: right
.-----------.       /              \      .-----------.
|           |     b1                b2    |           |
| MC --> a1-|-----'                  `----|-a2 --> MC |
|           |                             |           |
'-----------'     VETH pairs: aN//brN     '-----------'
                    In netns: eth0

Multi Domain

This topology is intended to be used for testing multiple routers. The bridge in the shared segment is only used to connect the two VETH pairs.

      netns: left                       netns: right
     .-------------.                   .-------------.
     |  smcrouted  |                   |  smcrouted  |
     |    /   \    |       br0         |    /   \    |
MC --> eth1   eth0 |      /   \        | eth0   eth1 <-- MC
     |            `------'     '-------'             |
     '-------------'  192.168.0.0/24   '-------------'
       10.0.0.0/24                       10.0.0.0/24

The idea is to provide a very tricky, but also very common, use case; replicated setups with the same IP subnet forwarding multicast to a shared LAN. Commonly worked around using 1:1 NAT, or IP masquerading. Neither of which is really best friends with IP multicast routing.

Tests

Advanced Routing

The test use ten ingressing multicast streams, starting at 225.1.2.3. With a single initial SSM route matching one of the streams. The remaining nine are installed in the kernel MFC with a stop-filter.

  • Verify that the SSM route works
  • Verify that no other multicast stream is forwarded

Now, add an ASM route for 225.1.2.3/29 and verify that the new ASM route matches a subset of the installed stop-filters, changing them to proper SSM routes.

Remove the 225.1.2.3/29 route and verify that the filters are changed back to stop-filters, and that the first SSM stream (which is in the same range) is not affected.

Topology: Basic

Basic Routing

Verifies routing between two interfaces a1 and a2. Multicast is injected on a1 and tcpdump verifies function on a2.

Topology: Basic

Bridge VLANs

Slightly more advanced test case, a bridge with two VLAN interfaces on top and two VETH pairs acting as untagged ports to the bridge in each of the VLANs. The other end of each VETH pair is placed in an isolated network namespace to allow proper IP networking to be set up.

Topology: Isolated Bridged w/ VLANs

Dynamic Routes

Different combinations of (*,G/LEN) to (S/LEN, G) routing is tested here for both IPv4 and IPv6.

Topology: Basic

Expiration of Dynamic Routes

The command line option smcrouted -c SEC can be used to tweak the cache timeout for (*,G) routes. This test verifies that it works as intended for both IPv4 and IPv6.

Topology: Basic

Include Files

This test does not traffic or forwarding verification, it only tests that the include directive for smcroute.conf works.

Topology: Basic

IPv6 (S,G) and (*,G) Forwarding

Similar to the Bridged VLAN test, only with IPv6.

Topology: Basic

Isolated (*,G) Forwarding

This test is currently very similar to the Basic test, but can easily be extended with IPv6 support as well. The trick here is to use the nested network namespace support, introduced in the new Isolated topology.

The Isolated topology allows setting interface addresses, both IPv4 and IPv6 (!), regardless of the environment (and as long as the underlying Linux kernel supports it). This means a standard tool like ping can be used to send multicast. Lowering the barrier of entry to run tests.

Topology: Isolated

Join/Leave ASM/SSM

Verify ASM & SSM join and leave for IPv4 & IPv6. Since ASM and SSM cannot be mixed on the same interface (fallback to ASM occurs), we use different interfaces and verify operation by inspecting the Linux ip maddr and /proc/net/mcfilter output.

Topology: Basic

Join/Leave ASM/SSM with Prefix Length

Verify ASM & SSM join and leave for IPv4 & IPv6 in various prefix length combinations; (S/LEN, G), (S, G/LEN), and (S/LEN, G/LEN). Since ASM and SSM cannot be mixed on the same interface (fallback to ASM occurs), we use different interfaces and verify operation by inspecting the Linux ip maddr and /proc/net/mcfilter output.

Topology: Basic

Multiple Routers with 1:1 NAT

Verify multicast forwarding from two separate LANs to a shared segment, where the two separate LANs have the same IP subnet. To make things worse, the same IP source address will be used for both multicast senders.

Note, this test requires the host system also has iptables. If the test cannot find the iptables tool, it will exit 77 to trigger a SKIP in the test suite.

Topology: Multi Domain

Poison Pill Routes

Verifies (*,G/LEN) routes from a set of approved inbound interfaces are properly installed in the kernel MFC. While blocking traffic to the same groups from other inbound interfaces using stop-filter, or "poison pill", routes (no outbound interfaces). For details, see issue #143.

Note, this test assumed the origin S of inbound traffic differs between inbound interfaces. I.e., the same S on different inbound interfaces is not supported by smcrouted.

Topology: Multi

Reload .conf File (IPv4)

Verifies that reloading the .conf file using SIGHUP or reload command to smcroutectl does not disturb established flows, and that the resulting configuration is properly set in the kernel.

Topology: Multi

Reload .conf File (IPv6)

The same as the IPv4 test, but for IPv6.

Topology: Multi

VLAN Interfaces

Similar to the basic routing test, except VLAN interfaces are created on top of the base interfaces, and routing takes place there. This test is based on troglobit/smcroute#161.

Topology: Basic w/ VLANs