+#define NL_OK(nla, len) \
+ ((len) >= (int)sizeof(struct nlattr) \
+ && (nla)->nla_len >= sizeof(struct nlattr) \
+ && (nla)->nla_len <= (len))
+#define NL_NEXT(nla, attrlen) \
+ ((attrlen) -= RTA_ALIGN((nla)->nla_len), \
+ (struct nlattr *)(((char *)(nla)) + RTA_ALIGN((nla)->nla_len)))
+#define NL_RTA(r) \
+ ((struct nlattr *)(((char *)(r)) \
+ + NLMSG_ALIGN(sizeof(struct nlmsgerr))))
+
+static void netlink_parse_nlattr(struct nlattr **tb, int max,
+ struct nlattr *nla, int len)
+{
+ while (NL_OK(nla, len)) {
+ if (nla->nla_type <= max)
+ tb[nla->nla_type] = nla;
+ nla = NL_NEXT(nla, len);
+ }
+}
+
+static void netlink_parse_extended_ack(struct nlmsghdr *h)
+{
+ struct nlattr *tb[NLMSGERR_ATTR_MAX + 1];
+ const struct nlmsgerr *err =
+ (const struct nlmsgerr *)((uint8_t *)h
+ + NLMSG_ALIGN(
+ sizeof(struct nlmsghdr)));
+ const struct nlmsghdr *err_nlh = NULL;
+ uint32_t hlen = sizeof(*err);
+ const char *msg = NULL;
+ uint32_t off = 0;
+
+ if (!(h->nlmsg_flags & NLM_F_CAPPED))
+ hlen += h->nlmsg_len - NLMSG_ALIGN(sizeof(struct nlmsghdr));
+
+ memset(tb, 0, sizeof(tb));
+ netlink_parse_nlattr(tb, NLMSGERR_ATTR_MAX, NL_RTA(h), hlen);
+
+ if (tb[NLMSGERR_ATTR_MSG])
+ msg = (const char *)RTA_DATA(tb[NLMSGERR_ATTR_MSG]);
+
+ if (tb[NLMSGERR_ATTR_OFFS]) {
+ off = *(uint32_t *)RTA_DATA(tb[NLMSGERR_ATTR_OFFS]);
+
+ if (off > h->nlmsg_len) {
+ zlog_err("Invalid offset for NLMSGERR_ATTR_OFFS\n");
+ off = 0;
+ } else if (!(h->nlmsg_flags & NLM_F_CAPPED)) {
+ /*
+ * Header of failed message
+ * we are not doing anything currently with it
+ * but noticing it for later.
+ */
+ err_nlh = &err->msg;
+ zlog_warn("%s: Received %d extended Ack",
+ __PRETTY_FUNCTION__, err_nlh->nlmsg_type);
+ }
+ }
+
+ if (msg && *msg != '\0') {
+ bool is_err = !!err->error;
+
+ if (is_err)
+ zlog_err("Extended Error: %s", msg);
+ else
+ zlog_warn("Extended Warning: %s", msg);
+ }
+}
+