canbus: fix frame comparison semantics

Makefile.am

@@ -11,6 +11,8 @@ ECUTOOLS_SRC_FILES += src/canbus_logger.c src/canbus_log.c src/canbus_filelogger
 J2534_SRC_FILES = src/awsiot_client.c src/passthru_shadow_parser.c src/j2534.c src/j2534/apigateway.c src/vector.c src/myint.c
 
 ECUTOOLS_TEST_FILES = tests/check_j2534.c
+ECUTOOLS_CANBUS_TEST_FILES = tests/check_canbus.c
+
 
 # AWS IoT client directory
 IOT_CLIENT_DIR = src/aws_iot_src
@@ -74,11 +76,15 @@ ecutuned_SOURCES = $(SRC_FILES) src/ecutuned.c
 ecutuned_CFLAGS = -DUSESSL -DTHREADED $(INCLUDE_ALL_DIRS) $(COMPILER_FLAGS) $(LOG_FLAGS)
 ecutuned_LDFLAGS = $(LD_FLAG) $(EXTERNAL_LIBS)
 
-TESTS = check_j2534
-check_PROGRAMS = check_j2534
+TESTS = check_j2534 check_canbus
+check_PROGRAMS = check_j2534 check_canbus
+
 check_j2534_SOURCES = $(ECUTOOLS_TEST_FILES)
 check_j2534_LDFLAGS = $(LD_FLAG) -lcheck -lj2534
 
+check_canbus_SOURCES = $(ECUTOOLS_CANBUS_TEST_FILES) src/canbus.c
+check_canbus_LDADD = -lcheck -lpthread -lrt -lm -lsubunit
+
 bundle-install:
 	cd bindings/ruby && bundle install && cd -
 	cd cli && bundle install && cd -

src/canbus.c

@@ -47,9 +47,17 @@ void canbus_framecpy(struct can_frame * frame, char *buf) {
   }
 }
 
-unsigned int canbus_framecmp(struct can_frame *frame1, struct can_frame *frame2) {
-  if(frame1->can_id != frame2->can_id) return 1;
-  return strcmp((const char *)frame1->data, (const char *)frame2->data) == 0;
+unsigned int canbus_framecmp(struct can_frame *frame1,
+                             struct can_frame *frame2) {
+  if(frame1->can_id != frame2->can_id)
+    return 1;
+
+  if(frame1->can_dlc != frame2->can_dlc)
+    return 1;
+
+  return memcmp(frame1->data,
+                frame2->data,
+                frame1->can_dlc) != 0;
 }
 
 void canbus_init(canbus_client *canbus) {

tests/check_canbus.c

@@ -0,0 +1,128 @@
+#include <stdlib.h>
+#include <check.h>
+
+#include "canbus.h"
+
+START_TEST(test_canbus_framecmp_identical_frames)
+{
+    struct can_frame lhs = {
+        .can_id = 0x123,
+        .can_dlc = 4,
+        .data = { 0x01, 0x00, 0xAA, 0x55 }
+    };
+
+    struct can_frame rhs = {
+        .can_id = 0x123,
+        .can_dlc = 4,
+        .data = { 0x01, 0x00, 0xAA, 0x55 }
+    };
+
+    ck_assert_uint_eq(canbus_framecmp(&lhs, &rhs), 0);
+}
+END_TEST
+
+START_TEST(test_canbus_framecmp_detects_different_can_id)
+{
+    struct can_frame lhs = {
+        .can_id = 0x123,
+        .can_dlc = 2,
+        .data = { 0xAA, 0x55 }
+    };
+
+    struct can_frame rhs = {
+        .can_id = 0x124,
+        .can_dlc = 2,
+        .data = { 0xAA, 0x55 }
+    };
+
+    ck_assert_uint_ne(canbus_framecmp(&lhs, &rhs), 0);
+}
+END_TEST
+
+START_TEST(test_canbus_framecmp_detects_different_dlc)
+{
+    struct can_frame lhs = {
+        .can_id = 0x123,
+        .can_dlc = 2,
+        .data = { 0xAA, 0x55 }
+    };
+
+    struct can_frame rhs = {
+        .can_id = 0x123,
+        .can_dlc = 3,
+        .data = { 0xAA, 0x55, 0x00 }
+    };
+
+    ck_assert_uint_ne(canbus_framecmp(&lhs, &rhs), 0);
+}
+END_TEST
+
+START_TEST(test_canbus_framecmp_detects_binary_difference_after_null_byte)
+{
+    struct can_frame lhs = {
+        .can_id = 0x123,
+        .can_dlc = 4,
+        .data = { 0x01, 0x00, 0xAA, 0x55 }
+    };
+
+    struct can_frame rhs = {
+        .can_id = 0x123,
+        .can_dlc = 4,
+        .data = { 0x01, 0x00, 0xBB, 0x55 }
+    };
+
+    ck_assert_uint_ne(canbus_framecmp(&lhs, &rhs), 0);
+}
+END_TEST
+
+START_TEST(test_canbus_framecmp_detects_different_payload)
+{
+    struct can_frame lhs = {
+        .can_id = 0x123,
+        .can_dlc = 2,
+        .data = { 0xAA, 0x55 }
+    };
+
+    struct can_frame rhs = {
+        .can_id = 0x123,
+        .can_dlc = 2,
+        .data = { 0xAB, 0x55 }
+    };
+
+    ck_assert_uint_ne(canbus_framecmp(&lhs, &rhs), 0);
+}
+END_TEST
+
+Suite *create_canbus_suite(void)
+{
+    Suite *suite = suite_create("canbus");
+    TCase *tc_core = tcase_create("framecmp");
+
+    tcase_add_test(tc_core, test_canbus_framecmp_identical_frames);
+    tcase_add_test(tc_core, test_canbus_framecmp_detects_different_can_id);
+    tcase_add_test(tc_core, test_canbus_framecmp_detects_different_dlc);
+    tcase_add_test(tc_core, test_canbus_framecmp_detects_different_payload);
+    tcase_add_test(
+        tc_core,
+        test_canbus_framecmp_detects_binary_difference_after_null_byte
+    );
+
+    suite_add_tcase(suite, tc_core);
+
+    return suite;
+}
+
+int main(void)
+{
+    int num_fail;
+    Suite *suite = create_canbus_suite();
+    SRunner *sr = srunner_create(suite);
+
+    srunner_run_all(sr, CK_NORMAL);
+
+    num_fail = srunner_ntests_failed(sr);
+
+    srunner_free(sr);
+
+    return (num_fail == 0) ? EXIT_SUCCESS : EXIT_FAILURE;
+}