Add test case for resolving family IDs of large Generic Netlink families (those with 199+ multicast groups):
1. Tests that standard genl_ctrl_resolve() may fail due to: - Response size exceeding single message limit - Implementation expecting single response
2. Verifies custom my_genl_ctrl_resolve() works by: - Using dump mechanism to collect all responses - Properly handling multi-message replies - Correctly identifying target family
The test validates that large families can be reliably resolved despite kernel message size limitations.
Signed-off-by: Yana Bashlykova yana2bsh@gmail.com --- tools/testing/selftests/net/genetlink.c | 37 +++++++++++++++++++++++++ 1 file changed, 37 insertions(+)
diff --git a/tools/testing/selftests/net/genetlink.c b/tools/testing/selftests/net/genetlink.c index 0a05402caa20..361840aae918 100644 --- a/tools/testing/selftests/net/genetlink.c +++ b/tools/testing/selftests/net/genetlink.c @@ -1142,6 +1142,43 @@ TEST(genl_ctrl_policy) nl_socket_free(ctrl_sock); }
+/** + * TEST(resolve_large_family_id) - Tests resolution of family ID for + * LARGE_GENL Generic Netlink family + * + * Validates special handling required for families with many multicast groups (199+): + * 1. Standard genl_ctrl_resolve() fails due to message size limitations + * 2. Custom my_genl_ctrl_resolve() succeeds by using dump mechanism + * + * Background: + * - Kernel successfully registers large families + * - Standard resolution fails because: + * * Response doesn't fit in single message + * * genl_ctrl_resolve() expects single response + * - Custom solution works by: + * * Using dump request to get all messages + * * Searching for target family in callback + * + * Verification: + * 1. Custom resolver returns valid ID (> 0) + * 2. Standard resolver either fails or succeeds (platform-dependent) + */ + +TEST(resolve_large_family_id) +{ + int family_id; + int no_family_id; + + /* Test custom resolver */ + family_id = my_genl_ctrl_resolve(LARGE_GENL_FAMILY_NAME); + EXPECT_TRUE(family_id > 0); + + /* Test standard resolver (may fail) */ + no_family_id = genl_ctrl_resolve(socket_alloc_and_conn(), + LARGE_GENL_FAMILY_NAME); + EXPECT_TRUE(no_family_id > 0); +} + /** * TEST(capture_end) - Terminates Netlink traffic monitoring session *