return true;
}
-/* Return true if we're currently rate-limiting out-of-window ACKs and
- * thus shouldn't send a dupack right now. We rate-limit dupacks in
- * response to out-of-window SYNs or ACKs to mitigate ACK loops or DoS
- * attacks that send repeated SYNs or ACKs for the same connection. To
- * do this, we do not send a duplicate SYNACK or ACK if the remote
- * endpoint is sending out-of-window SYNs or pure ACKs at a high rate.
- */
-static inline bool tcp_oow_rate_limited(struct net *net,
- const struct sk_buff *skb,
- int mib_idx, u32 *last_oow_ack_time)
-{
- /* Data packets without SYNs are not likely part of an ACK loop. */
- if ((TCP_SKB_CB(skb)->seq != TCP_SKB_CB(skb)->end_seq) &&
- !tcp_hdr(skb)->syn)
- goto not_rate_limited;
-
- if (*last_oow_ack_time) {
- s32 elapsed = (s32)(tcp_time_stamp - *last_oow_ack_time);
-
- if (0 <= elapsed && elapsed < sysctl_tcp_invalid_ratelimit) {
- NET_INC_STATS_BH(net, mib_idx);
- return true; /* rate-limited: don't send yet! */
- }
- }
-
- *last_oow_ack_time = tcp_time_stamp;
-
-not_rate_limited:
- return false; /* not rate-limited: go ahead, send dupack now! */
-}
+bool tcp_oow_rate_limited(struct net *net, const struct sk_buff *skb,
+ int mib_idx, u32 *last_oow_ack_time);
static inline void tcp_mib_init(struct net *net)
{
return flag;
}
+/* Return true if we're currently rate-limiting out-of-window ACKs and
+ * thus shouldn't send a dupack right now. We rate-limit dupacks in
+ * response to out-of-window SYNs or ACKs to mitigate ACK loops or DoS
+ * attacks that send repeated SYNs or ACKs for the same connection. To
+ * do this, we do not send a duplicate SYNACK or ACK if the remote
+ * endpoint is sending out-of-window SYNs or pure ACKs at a high rate.
+ */
+bool tcp_oow_rate_limited(struct net *net, const struct sk_buff *skb,
+ int mib_idx, u32 *last_oow_ack_time)
+{
+ /* Data packets without SYNs are not likely part of an ACK loop. */
+ if ((TCP_SKB_CB(skb)->seq != TCP_SKB_CB(skb)->end_seq) &&
+ !tcp_hdr(skb)->syn)
+ goto not_rate_limited;
+
+ if (*last_oow_ack_time) {
+ s32 elapsed = (s32)(tcp_time_stamp - *last_oow_ack_time);
+
+ if (0 <= elapsed && elapsed < sysctl_tcp_invalid_ratelimit) {
+ NET_INC_STATS_BH(net, mib_idx);
+ return true; /* rate-limited: don't send yet! */
+ }
+ }
+
+ *last_oow_ack_time = tcp_time_stamp;
+
+not_rate_limited:
+ return false; /* not rate-limited: go ahead, send dupack now! */
+}
+
/* RFC 5961 7 [ACK Throttling] */
static void tcp_send_challenge_ack(struct sock *sk, const struct sk_buff *skb)
{