+
+struct tc_qdisc_block_exists_ctx {
+ __u32 block_index;
+ bool found;
+};
+
+static int tc_qdisc_block_exists_cb(struct nlmsghdr *n, void *arg)
+{
+ struct tc_qdisc_block_exists_ctx *ctx = arg;
+ struct tcmsg *t = NLMSG_DATA(n);
+ struct rtattr *tb[TCA_MAX+1];
+ int len = n->nlmsg_len;
+
+ if (n->nlmsg_type != RTM_NEWQDISC)
+ return 0;
+
+ len -= NLMSG_LENGTH(sizeof(*t));
+ if (len < 0)
+ return -1;
+
+ parse_rtattr(tb, TCA_MAX, TCA_RTA(t), len);
+
+ if (tb[TCA_KIND] == NULL)
+ return -1;
+
+ if (tb[TCA_INGRESS_BLOCK] &&
+ RTA_PAYLOAD(tb[TCA_INGRESS_BLOCK]) >= sizeof(__u32)) {
+ __u32 block = rta_getattr_u32(tb[TCA_INGRESS_BLOCK]);
+
+ if (block == ctx->block_index)
+ ctx->found = true;
+ }
+
+ if (tb[TCA_EGRESS_BLOCK] &&
+ RTA_PAYLOAD(tb[TCA_EGRESS_BLOCK]) >= sizeof(__u32)) {
+ __u32 block = rta_getattr_u32(tb[TCA_EGRESS_BLOCK]);
+
+ if (block == ctx->block_index)
+ ctx->found = true;
+ }
+ return 0;
+}
+
+bool tc_qdisc_block_exists(__u32 block_index)
+{
+ struct tc_qdisc_block_exists_ctx ctx = { .block_index = block_index };
+ struct tcmsg t = { .tcm_family = AF_UNSPEC };
+
+ if (rtnl_dump_request(&rth, RTM_GETQDISC, &t, sizeof(t)) < 0) {
+ perror("Cannot send dump request");
+ return false;
+ }
+
+ if (rtnl_dump_filter(&rth, tc_qdisc_block_exists_cb, &ctx) < 0) {
+ perror("Dump terminated\n");
+ return false;
+ }
+
+ return ctx.found;
+}