Implement automated test framework for the tc backend

First take at implementing the automated testing code for tc backend.
In a nutshell, what it's doing is expanding on the already existing
run-tc-test.py script. The expansion consists of:

- Compiling the generated C files to eBPF bytecode
- Extracting a P4TC kernel image from github
- Compiling P4TC's version of iproute2
- Spawning a VM using virtme to boot the P4TC kernel
- Executing the template script generated by the compiler
- Loading the generated eBPF parser and control blocks binaries using a
  TC P4 filter
- Parsing an STF in the samples directory detailing what packets to
  send/expect and what runtime rules to load
- Loading any specified runtime rules
- Sending the packets using scapy
- Verifying that the sent packets (and eventual received packets from
  the p4tc pipeline) and correct according to the STF file

The commands are sent to the VM using ssh through a bridge that connects
the host to the VM
After the test is finished both the bridge and the VM are destroyed

We also added an example (arp_responder) to exercise the testing framework

Signed-off-by: Victor Nogueira <[email protected]>

.github/workflows/ci-test-fedora.yml

@@ -50,5 +50,6 @@ jobs:
 
       - name: Run p4c tests (Fedora Linux)
         run: |
-          export PATH="$HOME/.local/bin:$PATH"; ctest --output-on-failure --schedule-random
+          # Avoid running p4tc stf tests for now
+          export PATH="$HOME/.local/bin:$PATH"; ctest --output-on-failure --schedule-random -E "p4tc_samples_stf|p4tc_cleanup|p4tc_setup"
         working-directory: ./build

.github/workflows/ci-test-mac.yml

@@ -58,7 +58,7 @@ jobs:
       - name: Run tests (MacOS)
         run: |
           source ~/.bash_profile
-          ctest --output-on-failure --schedule-random -E "bpf|ubpf|testgen|smith"
+          ctest --output-on-failure --schedule-random -E "bpf|ubpf|testgen|smith|p4tc"
         working-directory: ./build
 
   # Build and test p4c on MacOS 13 on x86.
@@ -105,5 +105,5 @@ jobs:
       - name: Run tests (MacOS)
         run: |
           source ~/.bash_profile
-          ctest --output-on-failure --schedule-random -E "bpf|ubpf|testgen|smith"
+          ctest --output-on-failure --schedule-random -E "bpf|ubpf|testgen|smith|p4tc"
         working-directory: ./build

backends/tc/CMakeLists.txt

@@ -14,6 +14,49 @@
 # and limitations under the License.
 #*****************************************************************************/
 
+if(NOT APPLE)
+  # Fetch and declare the libbpf library. Print out download state while setting up libbpf.
+  set(FETCHCONTENT_QUIET_PREV ${FETCHCONTENT_QUIET})
+  set(FETCHCONTENT_QUIET OFF)
+  fetchcontent_declare(
+    p4cbpfrepo
+    URL https://github.com/libbpf/libbpf/archive/refs/tags/v1.5.0.tar.gz
+    URL_HASH SHA256=53492aff6dd47e4da04ef5e672d753b9743848bdb38e9d90eafbe190b7983c44
+    SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR}/runtime/libbpf
+    USES_TERMINAL_DOWNLOAD TRUE
+    GIT_PROGRESS TRUE
+    DOWNLOAD_EXTRACT_TIMESTAMP TRUE
+  )
+  fetchcontent_makeavailable(p4cbpfrepo)
+  set(FETCHCONTENT_QUIET ${FETCHCONTENT_QUIET_PREV})
+  message("Building libbpf...")
+  execute_process(
+    COMMAND ${CMAKE_CURRENT_SOURCE_DIR}/runtime/build-libbpf
+    WORKING_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}"
+    COMMAND_ECHO STDOUT
+  )
+  message("Done with setting up libbpf for P4C.")
+
+  fetchcontent_declare(
+    iproute2repo
+    URL https://github.com/p4tc-dev/iproute2-p4tc-pub/archive/refs/tags/release-v17-rc6.tar.gz
+    URL_HASH SHA256=624c32a571f9f30d1070d9b23e96121ac79f9273df9ff6db4ee6d034ab983c5d
+    SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR}/runtime/iproute2-p4tc-pub
+    USES_TERMINAL_DOWNLOAD TRUE
+    GIT_PROGRESS TRUE
+    DOWNLOAD_EXTRACT_TIMESTAMP TRUE
+  )
+  fetchcontent_makeavailable(iproute2repo)
+  set(FETCHCONTENT_QUIET ${FETCHCONTENT_QUIET_PREV})
+  message("Building iproute2...")
+  execute_process(
+    COMMAND ${CMAKE_CURRENT_SOURCE_DIR}/runtime/build-iproute2 ${CMAKE_CURRENT_SOURCE_DIR}/runtime
+    WORKING_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}"
+    COMMAND_ECHO STDOUT
+  )
+  message("Done with setting up iproute2 for P4C.")
+endif()
+
 set(P4TC_BACKEND_SOURCES
     backend.cpp
     ebpfCodeGen.cpp
@@ -122,4 +165,20 @@ set(P4TC_COMPILER_DRIVER "${CMAKE_CURRENT_SOURCE_DIR}/run-tc-test.py")
 set (P4_16_SUITES
   "${P4C_SOURCE_DIR}/testdata/p4tc_samples/*.p4")
 
+# Setup fixture
+add_test(NAME p4tc_setup COMMAND bash ${P4C_SOURCE_DIR}/backends/tc/runtime/setup "https://api.github.com/repos/p4tc-dev/linux-p4tc-pub/releases/latest")
+set_tests_properties(p4tc_setup PROPERTIES FIXTURES_SETUP P4TCFixture)
+
+add_test(NAME p4tc_cleanup COMMAND bash ${P4C_SOURCE_DIR}/backends/tc/runtime/cleanup)
+set_tests_properties(p4tc_cleanup PROPERTIES FIXTURES_CLEANUP P4TCFixture)
+
+macro(p4tc_add_test_with_args tag driver isXfail alias p4test test_args cmake_args)
+  p4c_add_test_with_args(${tag} ${driver} ${isXfail} ${alias} ${p4test} ${test_args} "")
+  p4c_test_set_name(__testname ${tag} ${alias})
+  set_tests_properties(${__testname} PROPERTIES FIXTURES_REQUIRED P4TCFixture RESOURCE_LOCK "shared_lock")
+  set_tests_properties(${__testname} PROPERTIES RESOURCE_LOCK "shared_lock")
+  set_tests_properties(${__testname} PROPERTIES TIMEOUT 1000)
+endmacro(p4tc_add_test_with_args)
+
 p4c_add_tests("p4tc" ${P4TC_COMPILER_DRIVER} "${P4_16_SUITES}" "")
+p4tc_add_test_with_args("p4tc" ${P4TC_COMPILER_DRIVER} FALSE "testdata/p4tc_samples_stf/arp_respond.p4" "testdata/p4tc_samples_stf/arp_respond.p4" "-tf ${P4C_SOURCE_DIR}/testdata/p4tc_samples_stf/arp_respond.stf" "")