netlink: add snl(3) support for listing genetlink multicast groups

Reviewed by:	bapt
Differential Revision:	https://reviews.freebsd.org/D40282
MFC after:	2 weeks

2 files changed, 85 insertions, 9 deletions

diff --git a/sys/netlink/netlink_snl_generic.h b/sys/netlink/netlink_snl_generic.h
index 1a1e592aa54d..1324cf3da17a 100644
--- a/sys/netlink/netlink_snl_generic.h
+++ b/sys/netlink/netlink_snl_generic.h
@@ -52,9 +52,30 @@ static struct snl_field_parser snl_fp_genl[] = {};
 #define	SNL_DECLARE_GENL_PARSER(_name, _np)	SNL_DECLARE_PARSER(_name,\
     struct genlmsghdr, snl_fp_genl, _np)
 
+struct snl_genl_ctrl_mcast_group {
+	uint32_t mcast_grp_id;
+	char *mcast_grp_name;
+};
+
+struct snl_genl_ctrl_mcast_groups {
+	uint32_t num_groups;
+	struct snl_genl_ctrl_mcast_group **groups;
+};
+
+#define	_OUT(_field)	offsetof(struct snl_genl_ctrl_mcast_group, _field)
+static struct snl_attr_parser _nla_p_getmc[] = {
+	{ .type = CTRL_ATTR_MCAST_GRP_NAME, .off = _OUT(mcast_grp_name), .cb = snl_attr_get_string },
+	{ .type = CTRL_ATTR_MCAST_GRP_ID, .off = _OUT(mcast_grp_id), .cb = snl_attr_get_uint32 },
+};
+#undef _OUT
+SNL_DECLARE_ATTR_PARSER_EXT(_genl_ctrl_mc_parser,
+		sizeof(struct snl_genl_ctrl_mcast_group),
+		_nla_p_getmc, NULL);
+
 struct _getfamily_attrs {
 	uint16_t family_id;
 	char	*family_name;
+	struct snl_genl_ctrl_mcast_groups mcast_groups;
 };
 
 #define	_IN(_field)	offsetof(struct genlmsghdr, _field)
@@ -62,36 +83,52 @@ struct _getfamily_attrs {
 static struct snl_attr_parser _nla_p_getfam[] = {
 	{ .type = CTRL_ATTR_FAMILY_ID , .off = _OUT(family_id), .cb = snl_attr_get_uint16 },
 	{ .type = CTRL_ATTR_FAMILY_NAME, .off = _OUT(family_name), .cb = snl_attr_get_string },
+	{
+		.type = CTRL_ATTR_MCAST_GROUPS,
+		.off = _OUT(mcast_groups),
+		.cb = snl_attr_get_parray,
+		.arg = &_genl_ctrl_mc_parser,
+	},
 };
 #undef _IN
 #undef _OUT
 SNL_DECLARE_GENL_PARSER(_genl_ctrl_getfam_parser, _nla_p_getfam);
 
-static inline uint16_t
-snl_get_genl_family(struct snl_state *ss, const char *family_name)
+static bool
+snl_get_genl_family_info(struct snl_state *ss, const char *family_name,
+    struct _getfamily_attrs *attrs)
 {
 	struct snl_writer nw;
 	struct nlmsghdr *hdr;
 
+	memset(attrs, 0, sizeof(*attrs));
+
 	snl_init_writer(ss, &nw);
 	hdr = snl_create_genl_msg_request(&nw, GENL_ID_CTRL, CTRL_CMD_GETFAMILY);
 	snl_add_msg_attr_string(&nw, CTRL_ATTR_FAMILY_NAME, family_name);
 	if (snl_finalize_msg(&nw) == NULL || !snl_send_message(ss, hdr))
-		return (0);
+		return (false);
 
 	hdr = snl_read_reply(ss, hdr->nlmsg_seq);
 	if (hdr != NULL && hdr->nlmsg_type != NLMSG_ERROR) {
-		struct _getfamily_attrs attrs = {};
-
-		if (snl_parse_nlmsg(ss, hdr, &_genl_ctrl_getfam_parser, &attrs))
-			return (attrs.family_id);
+		if (snl_parse_nlmsg(ss, hdr, &_genl_ctrl_getfam_parser, attrs))
+			return (true);
 	}
 
-	return (0);
+	return (false);
+}
+
+static inline uint16_t
+snl_get_genl_family(struct snl_state *ss, const char *family_name)
+{
+	struct _getfamily_attrs attrs = {};
+
+	snl_get_genl_family_info(ss, family_name, &attrs);
+	return (attrs.family_id);
 }
 
 static const struct snl_hdr_parser *snl_all_genl_parsers[] = {
-	&_genl_ctrl_getfam_parser,
+	&_genl_ctrl_getfam_parser, &_genl_ctrl_mc_parser,
 };
 
 #endif
diff --git a/tests/sys/netlink/test_snl_generic.c b/tests/sys/netlink/test_snl_generic.c
index c65d134f080d..f3c11daf19e1 100644
--- a/tests/sys/netlink/test_snl_generic.c
+++ b/tests/sys/netlink/test_snl_generic.c
@@ -66,11 +66,50 @@ ATF_TC_BODY(test_snl_get_genl_family_failure, tc)
 	ATF_CHECK_EQ(snl_get_genl_family(&ss, "no-such-family"), 0);
 }
 
+ATF_TC(test_snl_get_genl_family_groups);
+ATF_TC_HEAD(test_snl_get_genl_family_groups, tc)
+{
+	atf_tc_set_md_var(tc, "descr", "Tests getting 'nlctrl' groups");
+}
+
+ATF_TC_BODY(test_snl_get_genl_family_groups, tc)
+{
+	struct snl_state ss;
+	struct snl_writer nw;
+	struct nlmsghdr *hdr;
+
+	require_netlink();
+
+	if (!snl_init(&ss, NETLINK_GENERIC))
+		atf_tc_fail("snl_init() failed");
+
+	snl_init_writer(&ss, &nw);
+	hdr = snl_create_genl_msg_request(&nw, GENL_ID_CTRL, CTRL_CMD_GETFAMILY);
+	snl_add_msg_attr_string(&nw, CTRL_ATTR_FAMILY_NAME, "nlctrl");
+	snl_finalize_msg(&nw);
+	snl_send_message(&ss, hdr);
+
+	hdr = snl_read_reply(&ss, hdr->nlmsg_seq);
+	ATF_CHECK(hdr != NULL);
+	ATF_CHECK(hdr->nlmsg_type != NLMSG_ERROR);
+
+	struct _getfamily_attrs attrs = {};
+
+	ATF_CHECK(snl_parse_nlmsg(&ss, hdr, &_genl_ctrl_getfam_parser, &attrs));
+	ATF_CHECK_EQ(attrs.mcast_groups.num_groups, 1);
+
+	struct snl_genl_ctrl_mcast_group *group = attrs.mcast_groups.groups[0];
+
+	ATF_CHECK(group->mcast_grp_id > 0);
+	ATF_CHECK(!strcmp(group->mcast_grp_name, "notify"));
+}
+
 ATF_TP_ADD_TCS(tp)
 {
 	ATF_TP_ADD_TC(tp, snl_verify_genl_parsers);
 	ATF_TP_ADD_TC(tp, test_snl_get_genl_family_success);
 	ATF_TP_ADD_TC(tp, test_snl_get_genl_family_failure);
+	ATF_TP_ADD_TC(tp, test_snl_get_genl_family_groups);
 
 	return (atf_no_error());
 }