#include "ccid.h"
#include "dccp.h"
+/* rate-limit for syncs in reply to sequence-invalid packets; RFC 4340, 7.5.4 */
+int sysctl_dccp_sync_ratelimit __read_mostly = HZ / 8;
+
static void dccp_fin(struct sock *sk, struct sk_buff *skb)
{
sk->sk_shutdown |= RCV_SHUTDOWN;
{
const struct dccp_hdr *dh = dccp_hdr(skb);
struct dccp_sock *dp = dccp_sk(sk);
- u64 lswl, lawl;
+ u64 lswl, lawl, seqno = DCCP_SKB_CB(skb)->dccpd_seq,
+ ackno = DCCP_SKB_CB(skb)->dccpd_ack_seq;
/*
* Step 5: Prepare sequence numbers for Sync
*/
if (dh->dccph_type == DCCP_PKT_SYNC ||
dh->dccph_type == DCCP_PKT_SYNCACK) {
- if (between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
- dp->dccps_awl, dp->dccps_awh) &&
- !before48(DCCP_SKB_CB(skb)->dccpd_seq, dp->dccps_swl))
- dccp_update_gsr(sk, DCCP_SKB_CB(skb)->dccpd_seq);
+ if (between48(ackno, dp->dccps_awl, dp->dccps_awh) &&
+ dccp_delta_seqno(dp->dccps_swl, seqno) >= 0)
+ dccp_update_gsr(sk, seqno);
else
return -1;
}
* Update S.GSR, S.SWL, S.SWH
* If P.type != Sync,
* Update S.GAR
- * Otherwise,
- * Send Sync packet acknowledging P.seqno
- * Drop packet and return
*/
lswl = dp->dccps_swl;
lawl = dp->dccps_awl;
if (dh->dccph_type == DCCP_PKT_CLOSEREQ ||
dh->dccph_type == DCCP_PKT_CLOSE ||
dh->dccph_type == DCCP_PKT_RESET) {
- lswl = dp->dccps_gsr;
- dccp_inc_seqno(&lswl);
+ lswl = ADD48(dp->dccps_gsr, 1);
lawl = dp->dccps_gar;
}
- if (between48(DCCP_SKB_CB(skb)->dccpd_seq, lswl, dp->dccps_swh) &&
- (DCCP_SKB_CB(skb)->dccpd_ack_seq == DCCP_PKT_WITHOUT_ACK_SEQ ||
- between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
- lawl, dp->dccps_awh))) {
- dccp_update_gsr(sk, DCCP_SKB_CB(skb)->dccpd_seq);
+ if (between48(seqno, lswl, dp->dccps_swh) &&
+ (ackno == DCCP_PKT_WITHOUT_ACK_SEQ ||
+ between48(ackno, lawl, dp->dccps_awh))) {
+ dccp_update_gsr(sk, seqno);
if (dh->dccph_type != DCCP_PKT_SYNC &&
- (DCCP_SKB_CB(skb)->dccpd_ack_seq !=
- DCCP_PKT_WITHOUT_ACK_SEQ))
- dp->dccps_gar = DCCP_SKB_CB(skb)->dccpd_ack_seq;
+ (ackno != DCCP_PKT_WITHOUT_ACK_SEQ))
+ dp->dccps_gar = ackno;
} else {
+ unsigned long now = jiffies;
+ /*
+ * Step 6: Check sequence numbers
+ * Otherwise,
+ * If P.type == Reset,
+ * Send Sync packet acknowledging S.GSR
+ * Otherwise,
+ * Send Sync packet acknowledging P.seqno
+ * Drop packet and return
+ *
+ * These Syncs are rate-limited as per RFC 4340, 7.5.4:
+ * at most 1 / (dccp_sync_rate_limit * HZ) Syncs per second.
+ */
+ if (time_before(now, (dp->dccps_rate_last +
+ sysctl_dccp_sync_ratelimit)))
+ return 0;
+
DCCP_WARN("DCCP: Step 6 failed for %s packet, "
"(LSWL(%llu) <= P.seqno(%llu) <= S.SWH(%llu)) and "
"(P.ackno %s or LAWL(%llu) <= P.ackno(%llu) <= S.AWH(%llu), "
"sending SYNC...\n", dccp_packet_name(dh->dccph_type),
- (unsigned long long) lswl,
- (unsigned long long) DCCP_SKB_CB(skb)->dccpd_seq,
+ (unsigned long long) lswl, (unsigned long long) seqno,
(unsigned long long) dp->dccps_swh,
- (DCCP_SKB_CB(skb)->dccpd_ack_seq ==
- DCCP_PKT_WITHOUT_ACK_SEQ) ? "doesn't exist" : "exists",
- (unsigned long long) lawl,
- (unsigned long long) DCCP_SKB_CB(skb)->dccpd_ack_seq,
+ (ackno == DCCP_PKT_WITHOUT_ACK_SEQ) ? "doesn't exist"
+ : "exists",
+ (unsigned long long) lawl, (unsigned long long) ackno,
(unsigned long long) dp->dccps_awh);
- dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq, DCCP_PKT_SYNC);
+
+ dp->dccps_rate_last = now;
+
+ if (dh->dccph_type == DCCP_PKT_RESET)
+ seqno = dp->dccps_gsr;
+ dccp_send_sync(sk, seqno, DCCP_PKT_SYNC);
return -1;
}
if (dp->dccps_role != DCCP_ROLE_CLIENT)
goto send_sync;
check_seq:
- if (!before48(DCCP_SKB_CB(skb)->dccpd_seq, dp->dccps_osr)) {
+ if (dccp_delta_seqno(dp->dccps_osr,
+ DCCP_SKB_CB(skb)->dccpd_seq) >= 0) {
send_sync:
dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq,
DCCP_PKT_SYNC);
if (dh->dccph_type == DCCP_PKT_RESPONSE) {
const struct inet_connection_sock *icsk = inet_csk(sk);
struct dccp_sock *dp = dccp_sk(sk);
+ long tstamp = dccp_timestamp();
/* Stop the REQUEST timer */
inet_csk_clear_xmit_timer(sk, ICSK_TIME_RETRANS);
if (dccp_parse_options(sk, skb))
goto out_invalid_packet;
+ /* Obtain usec RTT sample from SYN exchange (used by CCID 3) */
+ if (likely(dp->dccps_options_received.dccpor_timestamp_echo))
+ dp->dccps_syn_rtt = dccp_sample_rtt(sk, 10 * (tstamp -
+ dp->dccps_options_received.dccpor_timestamp_echo));
+
if (dccp_msk(sk)->dccpms_send_ack_vector &&
dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,
DCCP_SKB_CB(skb)->dccpd_seq,
return 0;
}
- if (unlikely(dh->dccph_type == DCCP_PKT_SYNC)) {
- dccp_send_sync(sk, dcb->dccpd_seq, DCCP_PKT_SYNCACK);
- goto discard;
- }
-
switch (sk->sk_state) {
case DCCP_CLOSED:
dcb->dccpd_reset_code = DCCP_RESET_CODE_NO_CONNECTION;
sk_wake_async(sk, 0, POLL_OUT);
break;
}
+ } else if (unlikely(dh->dccph_type == DCCP_PKT_SYNC)) {
+ dccp_send_sync(sk, dcb->dccpd_seq, DCCP_PKT_SYNCACK);
+ goto discard;
}
if (!queued) {
}
EXPORT_SYMBOL_GPL(dccp_rcv_state_process);
+
+/**
+ * dccp_sample_rtt - Validate and finalise computation of RTT sample
+ * @delta: number of microseconds between packet and acknowledgment
+ * The routine is kept generic to work in different contexts. It should be
+ * called immediately when the ACK used for the RTT sample arrives.
+ */
+u32 dccp_sample_rtt(struct sock *sk, long delta)
+{
+ /* dccpor_elapsed_time is either zeroed out or set and > 0 */
+ delta -= dccp_sk(sk)->dccps_options_received.dccpor_elapsed_time * 10;
+
+ if (unlikely(delta <= 0)) {
+ DCCP_WARN("unusable RTT sample %ld, using min\n", delta);
+ return DCCP_SANE_RTT_MIN;
+ }
+ if (unlikely(delta > DCCP_SANE_RTT_MAX)) {
+ DCCP_WARN("RTT sample %ld too large, using max\n", delta);
+ return DCCP_SANE_RTT_MAX;
+ }
+
+ return delta;
+}
+
+EXPORT_SYMBOL_GPL(dccp_sample_rtt);
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