Add (experimental) test harness to be able to run packet tests under kvm at CI time + interactively

.github/workflows/c-compile.yml

@@ -14,3 +14,12 @@ jobs:
       run: |
         cd nat46/modules
         KCPPFLAGS='-DNAT46_VERSION=\"test\" -Werror' make
+    - name: Install kvm
+      run: |
+        sudo apt-get install qemu-system-x86
+    - name: Install and run test harness
+      run: |
+        cd test-harness
+        ./run-test-harness
+
+

.gitignore

@@ -0,0 +1,12 @@
+test-harness/test-data/captured/*
+test-harness/myinit
+test-harness/initrd.gz
+test-harness/initrd/
+test-harness/my-kernel
+
+nat46/modules/.*
+nat46/modules/nat46.mod*
+nat46/modules/Module.symvers
+nat46/modules/modules.order
+nat46/modules/*.o
+nat46/modules/*.ko

nat46/modules/nat46-core.h

@@ -64,7 +64,7 @@ typedef struct {
   int debug;
 
   int npairs;
-  nat46_xlate_rulepair_t pairs[0]; /* npairs */
+  nat46_xlate_rulepair_t pairs[]; /* npairs */
 } nat46_instance_t;
 
 int nat46_ipv6_input(struct sk_buff *old_skb);

test-harness/README.md

@@ -0,0 +1,36 @@
+This is a (long overdue) test harness for the nat46.ko module.
+
+The goal is to trivially run it in two modes:
+
+- as a CI in github
+- as a local test bench
+
+The high-level setup is more or less how this module was originally written some years ago:
+a kernel running under KVM, mounting the host filesystem via p9, and loading
+the module from there.
+
+However, as an experiment, I decided to do it in a much more lightweight fashion -
+rather than going the classic route of building the disk image of the root device and
+mounting that, with the help of LLM I built a custom /init, which gives enough of
+a shell-like experience to do the system bring-up and tests within it.
+
+In part it is done to test-drive another project of mine: https://github.com/ayourtch/oside,
+whose purpose in life is to allow to relatively easily do packet manipulations from Rust.
+
+Admittedly, it is a fair bit less feature-complete than Scapy at this point, but not having
+to deal with installation and management of Python inside the disk image is arguably worth the hassle.
+
+The init shell has a command "oside", which gives a rudimentary TUI to edit the jsonl files with
+the packets. Also one can use "pcap2json" command inside the shell to convert the files inside the shell.
+
+The tests are sitting under tests/ directory, and need to be executed one-by-one from startup.run - this
+script is executed immediately at bootup. In the future the tests *may* be moved into autoexec.run, which
+is also run at startup, but with a delay that allows the user to break into interactive shell.
+
+Each test should configure nat46 device(s) as it sees fit, inject some packets, and capture the expected
+packets into test-data/captured/*testname*.jsonl. After the VM run concludes, each captured file is compared
+with its sibling file in test-data/expected/*testname*.jsonl, and is expected to be identical, modulo timestamps.
+
+Admittedly this is not *too* much of a framework, but hopefully should allow for some relatively useful tests
+to be done relatively easily.
+

test-harness/autoexec.run

@@ -0,0 +1 @@
+echo This is a test

test-harness/bin/check-test-result

@@ -0,0 +1,13 @@
+#!/bin/sh
+set -eux
+TESTNAME=$1
+
+rm -f /tmp/expected.jsonl
+rm -f /tmp/captured.jsonl
+
+
+jq 'del(.timestamp_us)' test-data/expected/${TESTNAME}.jsonl >/tmp/expected.jsonl
+jq 'del(.timestamp_us)' test-data/captured/${TESTNAME}.jsonl >/tmp/captured.jsonl
+
+diff -c /tmp/expected.jsonl /tmp/captured.jsonl
+

test-harness/run-test-harness

@@ -0,0 +1,105 @@
+#!/bin/bash
+set -eux
+
+# latest tag for https://github.com/ayourtch/nat46-kvm-test-harness/
+MYINIT_VERSION="v0.0.10"
+
+find_kernel_and_modules() {
+    local kernel_version=$(uname -r)
+
+    # Potential kernel paths
+    local potential_kernel_paths=(
+        "/boot/vmlinuz-${kernel_version}"
+        "/boot/vmlinux-${kernel_version}"
+        "/boot/linux-${kernel_version}"
+    )
+
+    # Potential module path locations
+    local potential_module_paths=(
+        "/lib/modules/${kernel_version}"
+        "/usr/lib/modules/${kernel_version}"
+        "/usr/local/lib/modules/${kernel_version}"
+    )
+
+    local kernel_file=""
+    for path in "${potential_kernel_paths[@]}"; do
+        if [ -f "$path" ]; then
+            kernel_file="$path"
+            break
+        fi
+    done
+
+    local module_path=""
+    for path in "${potential_module_paths[@]}"; do
+        if [ -d "$path" ]; then
+            module_path="$path"
+            break
+        fi
+    done
+
+    if [ -z "$kernel_file" ]; then
+        echo "Error: Could not find kernel file for version ${kernel_version}" >&2
+        return 1
+    fi
+
+    if [ -z "$module_path" ]; then
+        echo "Error: Could not find module directory for version ${kernel_version}" >&2
+        return 1
+    fi
+
+    # Export environment variables
+    export KERNEL_FILE="$kernel_file"
+    export KERNEL_MODULE_PATH="$module_path"
+
+    # Print out for verification
+    echo "Kernel File: $KERNEL_FILE"
+    echo "Kernel Module Path: $KERNEL_MODULE_PATH"
+}
+
+find_kernel_and_modules
+
+# download myinit - if doing local tests, feel free to make a symlink
+[ -e myinit ] || (wget https://github.com/ayourtch/nat46-kvm-test-harness/releases/download/${MYINIT_VERSION}/myinit && chmod +x myinit)
+
+# build the initrd
+rm -rf initrd && mkdir initrd
+find ${KERNEL_MODULE_PATH} -name "netfs.ko*" -exec cp {} initrd/ \;
+find ${KERNEL_MODULE_PATH} -name "9pnet.ko*" -exec cp {} initrd/ \;
+find ${KERNEL_MODULE_PATH} -name "9pnet_virtio.ko*" -exec cp {} initrd/ \;
+find ${KERNEL_MODULE_PATH} -name "9p.ko*" -exec cp {} initrd/ \;
+find ${KERNEL_MODULE_PATH} -name "nf_defrag_ipv6.ko*" -exec cp {} initrd/ \;
+
+# copy the nat46 module from the repo
+find .. -name nat46.ko -exec cp {} initrd/ \;
+
+cp myinit initrd/init
+( cd initrd/ && find . | cpio -o -H newc ) | gzip > initrd.gz
+
+export HOST_SRC_PATH=$(git rev-parse --show-toplevel)
+
+[ -f my-kernel ] || (sudo cp ${KERNEL_FILE} my-kernel && sudo chmod 644 my-kernel)
+
+kvm -kernel my-kernel \
+  -initrd initrd.gz \
+  -net nic,model=virtio,macaddr=52:54:00:12:34:56 \
+  -net user,hostfwd=tcp:127.0.0.1:4444-:22 \
+  -append 'console=hvc0' \
+  -chardev stdio,id=stdio,mux=on,signal=off \
+  -device virtio-serial-pci \
+  -device virtconsole,chardev=stdio \
+  -mon chardev=stdio \
+  -display none \
+  -fsdev local,id=fs1,path=${HOST_SRC_PATH},security_model=none \
+  -s \
+  -device virtio-9p-pci,fsdev=fs1,mount_tag=host-code
+
+
+# collect the test names
+cd tests
+ALL_TESTS=$(ls)
+cd ..
+
+# verify that all the tests are matching the expectations
+for t in $ALL_TESTS; do
+  bin/check-test-result $t
+done

test-harness/startup.run

@@ -0,0 +1,51 @@
+# This file is executed after the host filesystem is mounted
+# Modify this file to customize your test environment
+
+# List root directory to verify mount
+ls /
+
+# Load additional kernel modules
+insmod /nf_defrag_ipv6.ko
+insmod /nat46.ko
+
+ifconfig lo 127.0.0.1 netmask 255.0.0.0
+ifconfig lo ::1/128
+ifconfig lo up
+
+# Setup TAP interfaces
+mknod /dev/net/tun c 10 200
+tap add tap0
+ifconfig tap0 192.168.1.1 netmask 255.255.255.0
+ifconfig tap0 2001:db8:1::1/64
+ifconfig tap0 up
+tap add tap1
+ifconfig tap1 2001:db8::1/64
+ifconfig tap1 up
+ifconfig
+
+# set the mac addresses
+ifconfig tap0 hw ether 0E:86:3C:CD:51:CA
+ifconfig tap1 hw ether 00:11:22:33:44:55
+ifconfig nat46dev up
+
+# add phantom hosts
+fakehost add tap1 fe80::1 icmp router
+fakehost add tap1 2001:db8::2 icmp router
+fakehost add tap1 fe80::2 icmp
+# ping ipv6 default gateway global
+# ping 2001:db8::2
+ping fe80::1%tap1
+
+ip -6 route add ::/0 via fe80::1 dev tap1
+ifconfig tap0 up promisc
+
+# start droptrace for diagnostics
+mkdir -p /sys/kernel
+droptrace start
+
+echo 1 >/proc/sys/net/ipv4/ip_forward
+echo 1 >/proc/sys/net/ipv6/conf/all/forwarding
+
+run /mnt/host/test-harness/tests/basic/test.run
+
+

test-harness/test-data/expected/basic.jsonl

@@ -0,0 +1,2 @@
+{"timestamp_us":1761854670878200,"direction":"tx","layers":[{"layertype":"Ip","version":4,"ihl":5,"tos":0,"len":84,"id":4,"flags":{"reserved":false,"dont_fragment":false,"more_fragments":false,"fragment_offset":0},"ttl":254,"proto":6,"chksum":60035,"src":"192.168.1.100","dst":"8.8.8.8","options":[]},{"layertype":"Tcp","sport":12345,"dport":81,"seq":0,"ack":0,"dataofs":5,"reserved":0,"flags":2,"window":8192,"chksum":60790,"urgptr":0},{"layertype":"raw","data":[42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42]}]}
+{"timestamp_us":1761854670881112,"direction":"rx","layers":[{"layertype":"Ipv6","version_class":1610612736,"payload_length":64,"next_header":6,"hop_limit":254,"src":"2001:db8:1:1::1","dst":"2001:4860:4860::8888"},{"layertype":"Tcp","sport":12345,"dport":81,"seq":0,"ack":0,"dataofs":5,"reserved":0,"flags":2,"window":8192,"chksum":22663,"urgptr":0},{"layertype":"raw","data":[42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42]}]}

test-harness/tests/basic/inject-tap0.jsonl

@@ -0,0 +1,5 @@
+{"timestamp_us":0,"layers":[{"layertype":"ether","dst":"FF:FF:FF:FF:FF:FF","src":"00:00:00:00:00:00","etype":0}]}
+{"timestamp_us":1000000,"layers":[{"layertype":"ether","dst":"0E:86:3C:CD:51:CA","src":"52:55:0A:00:02:02","etype":2048},{"layertype":"Ip","version":4,"ihl":5,"tos":0,"len":84,"id":4,"flags":{"reserved":false,"dont_fragment":false,"more_fragments":false,"fragment_offset":0},"ttl":255,"proto":6,"chksum":59779,"src":"192.168.1.100","dst":"8.8.8.8","options":[]},{"layertype":"Tcp","sport":12345,"dport":81,"seq":0,"ack":0,"dataofs":5,"reserved":0,"flags":2,"window":8192,"chksum":60790,"urgptr":0},{"layertype":"raw","data":[42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42]}]}
+{"timestamp_us":1000000,"layers":[{"layertype":"ether","dst":"86:8B:D5:ED:1E:03","src":"52:55:0A:00:02:02","etype":34525},{"layertype":"Ipv6","version_class":1610612736,"payload_length":65,"next_header":17,"hop_limit":64,"src":"2001:db8::1","dst":"2001:db8::2"},{"layertype":"Udp","sport":6666,"dport":888,"len":65,"chksum":49112},{"layertype":"raw","data":[42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42,42]}]}
+{"timestamp_us":2000000,"layers":[{"layertype":"ether","dst":"FF:FF:FF:FF:FF:FF","src":"00:00:00:00:00:00","etype":0}]}
+

test-harness/tests/basic/test.run

@@ -0,0 +1,21 @@
+echo add nat46dev > /proc/net/nat46/control
+ifconfig nat46dev up
+ip route add 0.0.0.0/0 dev nat46dev
+
+echo config nat46dev debug 255 >/proc/net/nat46/control
+echo insert nat46dev local.v4 192.168.1.100/32 local.v6 2001:db8:1:1::1/128 local.style NONE remote.v4 8.8.8.8/32 remote.v6 2001:4860:4860::8888/128 remote.style NONE >/proc/net/nat46/control
+echo insert nat46dev local.v4 192.168.1.101/32 local.v6 2001:db8:1:1::2/128 local.style NONE remote.v4 8.8.8.8/32 remote.v6 2001:4860:4860::8888/128 remote.style NONE >/proc/net/nat46/control
+
+capture start nat46dev /mnt/host/test-harness/test-data/captured/basic.jsonl
+
+# inject packets
+inject /mnt/host/test-harness/tests/basic/inject-tap0.jsonl tap0
+
+# remove the nat46 device
+echo del nat46dev >/proc/net/nat46/control
+
+capture stop all
+
+echo nat46 packets:
+cat /mnt/host/test-harness/test-data/captured/basic.jsonl
+