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-rw-r--r--net/dccp/ccids/ccid2.c805
1 files changed, 805 insertions, 0 deletions
diff --git a/net/dccp/ccids/ccid2.c b/net/dccp/ccids/ccid2.c
new file mode 100644
index 0000000..9a43073
--- /dev/null
+++ b/net/dccp/ccids/ccid2.c
@@ -0,0 +1,805 @@
+/*
+ * net/dccp/ccids/ccid2.c
+ *
+ * Copyright (c) 2005, 2006 Andrea Bittau <a.bittau@cs.ucl.ac.uk>
+ *
+ * Changes to meet Linux coding standards, and DCCP infrastructure fixes.
+ *
+ * Copyright (c) 2006 Arnaldo Carvalho de Melo <acme@conectiva.com.br>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+/*
+ * This implementation should follow RFC 4341
+ */
+
+#include "../ccid.h"
+#include "../dccp.h"
+#include "ccid2.h"
+
+
+#ifdef CONFIG_IP_DCCP_CCID2_DEBUG
+static int ccid2_debug;
+#define ccid2_pr_debug(format, a...) DCCP_PR_DEBUG(ccid2_debug, format, ##a)
+
+static void ccid2_hc_tx_check_sanity(const struct ccid2_hc_tx_sock *hctx)
+{
+ int len = 0;
+ int pipe = 0;
+ struct ccid2_seq *seqp = hctx->ccid2hctx_seqh;
+
+ /* there is data in the chain */
+ if (seqp != hctx->ccid2hctx_seqt) {
+ seqp = seqp->ccid2s_prev;
+ len++;
+ if (!seqp->ccid2s_acked)
+ pipe++;
+
+ while (seqp != hctx->ccid2hctx_seqt) {
+ struct ccid2_seq *prev = seqp->ccid2s_prev;
+
+ len++;
+ if (!prev->ccid2s_acked)
+ pipe++;
+
+ /* packets are sent sequentially */
+ BUG_ON(dccp_delta_seqno(seqp->ccid2s_seq,
+ prev->ccid2s_seq ) >= 0);
+ BUG_ON(time_before(seqp->ccid2s_sent,
+ prev->ccid2s_sent));
+
+ seqp = prev;
+ }
+ }
+
+ BUG_ON(pipe != hctx->ccid2hctx_pipe);
+ ccid2_pr_debug("len of chain=%d\n", len);
+
+ do {
+ seqp = seqp->ccid2s_prev;
+ len++;
+ } while (seqp != hctx->ccid2hctx_seqh);
+
+ ccid2_pr_debug("total len=%d\n", len);
+ BUG_ON(len != hctx->ccid2hctx_seqbufc * CCID2_SEQBUF_LEN);
+}
+#else
+#define ccid2_pr_debug(format, a...)
+#define ccid2_hc_tx_check_sanity(hctx)
+#endif
+
+static int ccid2_hc_tx_alloc_seq(struct ccid2_hc_tx_sock *hctx)
+{
+ struct ccid2_seq *seqp;
+ int i;
+
+ /* check if we have space to preserve the pointer to the buffer */
+ if (hctx->ccid2hctx_seqbufc >= (sizeof(hctx->ccid2hctx_seqbuf) /
+ sizeof(struct ccid2_seq*)))
+ return -ENOMEM;
+
+ /* allocate buffer and initialize linked list */
+ seqp = kmalloc(CCID2_SEQBUF_LEN * sizeof(struct ccid2_seq), gfp_any());
+ if (seqp == NULL)
+ return -ENOMEM;
+
+ for (i = 0; i < (CCID2_SEQBUF_LEN - 1); i++) {
+ seqp[i].ccid2s_next = &seqp[i + 1];
+ seqp[i + 1].ccid2s_prev = &seqp[i];
+ }
+ seqp[CCID2_SEQBUF_LEN - 1].ccid2s_next = seqp;
+ seqp->ccid2s_prev = &seqp[CCID2_SEQBUF_LEN - 1];
+
+ /* This is the first allocation. Initiate the head and tail. */
+ if (hctx->ccid2hctx_seqbufc == 0)
+ hctx->ccid2hctx_seqh = hctx->ccid2hctx_seqt = seqp;
+ else {
+ /* link the existing list with the one we just created */
+ hctx->ccid2hctx_seqh->ccid2s_next = seqp;
+ seqp->ccid2s_prev = hctx->ccid2hctx_seqh;
+
+ hctx->ccid2hctx_seqt->ccid2s_prev = &seqp[CCID2_SEQBUF_LEN - 1];
+ seqp[CCID2_SEQBUF_LEN - 1].ccid2s_next = hctx->ccid2hctx_seqt;
+ }
+
+ /* store the original pointer to the buffer so we can free it */
+ hctx->ccid2hctx_seqbuf[hctx->ccid2hctx_seqbufc] = seqp;
+ hctx->ccid2hctx_seqbufc++;
+
+ return 0;
+}
+
+static int ccid2_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb)
+{
+ struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
+
+ if (hctx->ccid2hctx_pipe < hctx->ccid2hctx_cwnd)
+ return 0;
+
+ return 1; /* XXX CCID should dequeue when ready instead of polling */
+}
+
+static void ccid2_change_l_ack_ratio(struct sock *sk, u32 val)
+{
+ struct dccp_sock *dp = dccp_sk(sk);
+ u32 max_ratio = DIV_ROUND_UP(ccid2_hc_tx_sk(sk)->ccid2hctx_cwnd, 2);
+
+ /*
+ * Ensure that Ack Ratio does not exceed ceil(cwnd/2), which is (2) from
+ * RFC 4341, 6.1.2. We ignore the statement that Ack Ratio 2 is always
+ * acceptable since this causes starvation/deadlock whenever cwnd < 2.
+ * The same problem arises when Ack Ratio is 0 (ie. Ack Ratio disabled).
+ */
+ if (val == 0 || val > max_ratio) {
+ DCCP_WARN("Limiting Ack Ratio (%u) to %u\n", val, max_ratio);
+ val = max_ratio;
+ }
+ if (val > 0xFFFF) /* RFC 4340, 11.3 */
+ val = 0xFFFF;
+
+ if (val == dp->dccps_l_ack_ratio)
+ return;
+
+ ccid2_pr_debug("changing local ack ratio to %u\n", val);
+ dp->dccps_l_ack_ratio = val;
+}
+
+static void ccid2_change_srtt(struct ccid2_hc_tx_sock *hctx, long val)
+{
+ ccid2_pr_debug("change SRTT to %ld\n", val);
+ hctx->ccid2hctx_srtt = val;
+}
+
+static void ccid2_start_rto_timer(struct sock *sk);
+
+static void ccid2_hc_tx_rto_expire(unsigned long data)
+{
+ struct sock *sk = (struct sock *)data;
+ struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
+ long s;
+
+ bh_lock_sock(sk);
+ if (sock_owned_by_user(sk)) {
+ sk_reset_timer(sk, &hctx->ccid2hctx_rtotimer,
+ jiffies + HZ / 5);
+ goto out;
+ }
+
+ ccid2_pr_debug("RTO_EXPIRE\n");
+
+ ccid2_hc_tx_check_sanity(hctx);
+
+ /* back-off timer */
+ hctx->ccid2hctx_rto <<= 1;
+
+ s = hctx->ccid2hctx_rto / HZ;
+ if (s > 60)
+ hctx->ccid2hctx_rto = 60 * HZ;
+
+ ccid2_start_rto_timer(sk);
+
+ /* adjust pipe, cwnd etc */
+ hctx->ccid2hctx_ssthresh = hctx->ccid2hctx_cwnd / 2;
+ if (hctx->ccid2hctx_ssthresh < 2)
+ hctx->ccid2hctx_ssthresh = 2;
+ hctx->ccid2hctx_cwnd = 1;
+ hctx->ccid2hctx_pipe = 0;
+
+ /* clear state about stuff we sent */
+ hctx->ccid2hctx_seqt = hctx->ccid2hctx_seqh;
+ hctx->ccid2hctx_packets_acked = 0;
+
+ /* clear ack ratio state. */
+ hctx->ccid2hctx_rpseq = 0;
+ hctx->ccid2hctx_rpdupack = -1;
+ ccid2_change_l_ack_ratio(sk, 1);
+ ccid2_hc_tx_check_sanity(hctx);
+out:
+ bh_unlock_sock(sk);
+ sock_put(sk);
+}
+
+static void ccid2_start_rto_timer(struct sock *sk)
+{
+ struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
+
+ ccid2_pr_debug("setting RTO timeout=%ld\n", hctx->ccid2hctx_rto);
+
+ BUG_ON(timer_pending(&hctx->ccid2hctx_rtotimer));
+ sk_reset_timer(sk, &hctx->ccid2hctx_rtotimer,
+ jiffies + hctx->ccid2hctx_rto);
+}
+
+static void ccid2_hc_tx_packet_sent(struct sock *sk, int more, unsigned int len)
+{
+ struct dccp_sock *dp = dccp_sk(sk);
+ struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
+ struct ccid2_seq *next;
+
+ hctx->ccid2hctx_pipe++;
+
+ hctx->ccid2hctx_seqh->ccid2s_seq = dp->dccps_gss;
+ hctx->ccid2hctx_seqh->ccid2s_acked = 0;
+ hctx->ccid2hctx_seqh->ccid2s_sent = jiffies;
+
+ next = hctx->ccid2hctx_seqh->ccid2s_next;
+ /* check if we need to alloc more space */
+ if (next == hctx->ccid2hctx_seqt) {
+ if (ccid2_hc_tx_alloc_seq(hctx)) {
+ DCCP_CRIT("packet history - out of memory!");
+ /* FIXME: find a more graceful way to bail out */
+ return;
+ }
+ next = hctx->ccid2hctx_seqh->ccid2s_next;
+ BUG_ON(next == hctx->ccid2hctx_seqt);
+ }
+ hctx->ccid2hctx_seqh = next;
+
+ ccid2_pr_debug("cwnd=%d pipe=%d\n", hctx->ccid2hctx_cwnd,
+ hctx->ccid2hctx_pipe);
+
+ /*
+ * FIXME: The code below is broken and the variables have been removed
+ * from the socket struct. The `ackloss' variable was always set to 0,
+ * and with arsent there are several problems:
+ * (i) it doesn't just count the number of Acks, but all sent packets;
+ * (ii) it is expressed in # of packets, not # of windows, so the
+ * comparison below uses the wrong formula: Appendix A of RFC 4341
+ * comes up with the number K = cwnd / (R^2 - R) of consecutive windows
+ * of data with no lost or marked Ack packets. If arsent were the # of
+ * consecutive Acks received without loss, then Ack Ratio needs to be
+ * decreased by 1 when
+ * arsent >= K * cwnd / R = cwnd^2 / (R^3 - R^2)
+ * where cwnd / R is the number of Acks received per window of data
+ * (cf. RFC 4341, App. A). The problems are that
+ * - arsent counts other packets as well;
+ * - the comparison uses a formula different from RFC 4341;
+ * - computing a cubic/quadratic equation each time is too complicated.
+ * Hence a different algorithm is needed.
+ */
+#if 0
+ /* Ack Ratio. Need to maintain a concept of how many windows we sent */
+ hctx->ccid2hctx_arsent++;
+ /* We had an ack loss in this window... */
+ if (hctx->ccid2hctx_ackloss) {
+ if (hctx->ccid2hctx_arsent >= hctx->ccid2hctx_cwnd) {
+ hctx->ccid2hctx_arsent = 0;
+ hctx->ccid2hctx_ackloss = 0;
+ }
+ } else {
+ /* No acks lost up to now... */
+ /* decrease ack ratio if enough packets were sent */
+ if (dp->dccps_l_ack_ratio > 1) {
+ /* XXX don't calculate denominator each time */
+ int denom = dp->dccps_l_ack_ratio * dp->dccps_l_ack_ratio -
+ dp->dccps_l_ack_ratio;
+
+ denom = hctx->ccid2hctx_cwnd * hctx->ccid2hctx_cwnd / denom;
+
+ if (hctx->ccid2hctx_arsent >= denom) {
+ ccid2_change_l_ack_ratio(sk, dp->dccps_l_ack_ratio - 1);
+ hctx->ccid2hctx_arsent = 0;
+ }
+ } else {
+ /* we can't increase ack ratio further [1] */
+ hctx->ccid2hctx_arsent = 0; /* or maybe set it to cwnd*/
+ }
+ }
+#endif
+
+ /* setup RTO timer */
+ if (!timer_pending(&hctx->ccid2hctx_rtotimer))
+ ccid2_start_rto_timer(sk);
+
+#ifdef CONFIG_IP_DCCP_CCID2_DEBUG
+ do {
+ struct ccid2_seq *seqp = hctx->ccid2hctx_seqt;
+
+ while (seqp != hctx->ccid2hctx_seqh) {
+ ccid2_pr_debug("out seq=%llu acked=%d time=%lu\n",
+ (unsigned long long)seqp->ccid2s_seq,
+ seqp->ccid2s_acked, seqp->ccid2s_sent);
+ seqp = seqp->ccid2s_next;
+ }
+ } while (0);
+ ccid2_pr_debug("=========\n");
+ ccid2_hc_tx_check_sanity(hctx);
+#endif
+}
+
+/* XXX Lame code duplication!
+ * returns -1 if none was found.
+ * else returns the next offset to use in the function call.
+ */
+static int ccid2_ackvector(struct sock *sk, struct sk_buff *skb, int offset,
+ unsigned char **vec, unsigned char *veclen)
+{
+ const struct dccp_hdr *dh = dccp_hdr(skb);
+ unsigned char *options = (unsigned char *)dh + dccp_hdr_len(skb);
+ unsigned char *opt_ptr;
+ const unsigned char *opt_end = (unsigned char *)dh +
+ (dh->dccph_doff * 4);
+ unsigned char opt, len;
+ unsigned char *value;
+
+ BUG_ON(offset < 0);
+ options += offset;
+ opt_ptr = options;
+ if (opt_ptr >= opt_end)
+ return -1;
+
+ while (opt_ptr != opt_end) {
+ opt = *opt_ptr++;
+ len = 0;
+ value = NULL;
+
+ /* Check if this isn't a single byte option */
+ if (opt > DCCPO_MAX_RESERVED) {
+ if (opt_ptr == opt_end)
+ goto out_invalid_option;
+
+ len = *opt_ptr++;
+ if (len < 3)
+ goto out_invalid_option;
+ /*
+ * Remove the type and len fields, leaving
+ * just the value size
+ */
+ len -= 2;
+ value = opt_ptr;
+ opt_ptr += len;
+
+ if (opt_ptr > opt_end)
+ goto out_invalid_option;
+ }
+
+ switch (opt) {
+ case DCCPO_ACK_VECTOR_0:
+ case DCCPO_ACK_VECTOR_1:
+ *vec = value;
+ *veclen = len;
+ return offset + (opt_ptr - options);
+ }
+ }
+
+ return -1;
+
+out_invalid_option:
+ DCCP_BUG("Invalid option - this should not happen (previous parsing)!");
+ return -1;
+}
+
+static void ccid2_hc_tx_kill_rto_timer(struct sock *sk)
+{
+ struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
+
+ sk_stop_timer(sk, &hctx->ccid2hctx_rtotimer);
+ ccid2_pr_debug("deleted RTO timer\n");
+}
+
+static inline void ccid2_new_ack(struct sock *sk,
+ struct ccid2_seq *seqp,
+ unsigned int *maxincr)
+{
+ struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
+
+ if (hctx->ccid2hctx_cwnd < hctx->ccid2hctx_ssthresh) {
+ if (*maxincr > 0 && ++hctx->ccid2hctx_packets_acked == 2) {
+ hctx->ccid2hctx_cwnd += 1;
+ *maxincr -= 1;
+ hctx->ccid2hctx_packets_acked = 0;
+ }
+ } else if (++hctx->ccid2hctx_packets_acked >= hctx->ccid2hctx_cwnd) {
+ hctx->ccid2hctx_cwnd += 1;
+ hctx->ccid2hctx_packets_acked = 0;
+ }
+
+ /* update RTO */
+ if (hctx->ccid2hctx_srtt == -1 ||
+ time_after(jiffies, hctx->ccid2hctx_lastrtt + hctx->ccid2hctx_srtt)) {
+ unsigned long r = (long)jiffies - (long)seqp->ccid2s_sent;
+ int s;
+
+ /* first measurement */
+ if (hctx->ccid2hctx_srtt == -1) {
+ ccid2_pr_debug("R: %lu Time=%lu seq=%llu\n",
+ r, jiffies,
+ (unsigned long long)seqp->ccid2s_seq);
+ ccid2_change_srtt(hctx, r);
+ hctx->ccid2hctx_rttvar = r >> 1;
+ } else {
+ /* RTTVAR */
+ long tmp = hctx->ccid2hctx_srtt - r;
+ long srtt;
+
+ if (tmp < 0)
+ tmp *= -1;
+
+ tmp >>= 2;
+ hctx->ccid2hctx_rttvar *= 3;
+ hctx->ccid2hctx_rttvar >>= 2;
+ hctx->ccid2hctx_rttvar += tmp;
+
+ /* SRTT */
+ srtt = hctx->ccid2hctx_srtt;
+ srtt *= 7;
+ srtt >>= 3;
+ tmp = r >> 3;
+ srtt += tmp;
+ ccid2_change_srtt(hctx, srtt);
+ }
+ s = hctx->ccid2hctx_rttvar << 2;
+ /* clock granularity is 1 when based on jiffies */
+ if (!s)
+ s = 1;
+ hctx->ccid2hctx_rto = hctx->ccid2hctx_srtt + s;
+
+ /* must be at least a second */
+ s = hctx->ccid2hctx_rto / HZ;
+ /* DCCP doesn't require this [but I like it cuz my code sux] */
+#if 1
+ if (s < 1)
+ hctx->ccid2hctx_rto = HZ;
+#endif
+ /* max 60 seconds */
+ if (s > 60)
+ hctx->ccid2hctx_rto = HZ * 60;
+
+ hctx->ccid2hctx_lastrtt = jiffies;
+
+ ccid2_pr_debug("srtt: %ld rttvar: %ld rto: %ld (HZ=%d) R=%lu\n",
+ hctx->ccid2hctx_srtt, hctx->ccid2hctx_rttvar,
+ hctx->ccid2hctx_rto, HZ, r);
+ }
+
+ /* we got a new ack, so re-start RTO timer */
+ ccid2_hc_tx_kill_rto_timer(sk);
+ ccid2_start_rto_timer(sk);
+}
+
+static void ccid2_hc_tx_dec_pipe(struct sock *sk)
+{
+ struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
+
+ if (hctx->ccid2hctx_pipe == 0)
+ DCCP_BUG("pipe == 0");
+ else
+ hctx->ccid2hctx_pipe--;
+
+ if (hctx->ccid2hctx_pipe == 0)
+ ccid2_hc_tx_kill_rto_timer(sk);
+}
+
+static void ccid2_congestion_event(struct sock *sk, struct ccid2_seq *seqp)
+{
+ struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
+
+ if (time_before(seqp->ccid2s_sent, hctx->ccid2hctx_last_cong)) {
+ ccid2_pr_debug("Multiple losses in an RTT---treating as one\n");
+ return;
+ }
+
+ hctx->ccid2hctx_last_cong = jiffies;
+
+ hctx->ccid2hctx_cwnd = hctx->ccid2hctx_cwnd / 2 ? : 1U;
+ hctx->ccid2hctx_ssthresh = max(hctx->ccid2hctx_cwnd, 2U);
+
+ /* Avoid spurious timeouts resulting from Ack Ratio > cwnd */
+ if (dccp_sk(sk)->dccps_l_ack_ratio > hctx->ccid2hctx_cwnd)
+ ccid2_change_l_ack_ratio(sk, hctx->ccid2hctx_cwnd);
+}
+
+static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
+{
+ struct dccp_sock *dp = dccp_sk(sk);
+ struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
+ u64 ackno, seqno;
+ struct ccid2_seq *seqp;
+ unsigned char *vector;
+ unsigned char veclen;
+ int offset = 0;
+ int done = 0;
+ unsigned int maxincr = 0;
+
+ ccid2_hc_tx_check_sanity(hctx);
+ /* check reverse path congestion */
+ seqno = DCCP_SKB_CB(skb)->dccpd_seq;
+
+ /* XXX this whole "algorithm" is broken. Need to fix it to keep track
+ * of the seqnos of the dupacks so that rpseq and rpdupack are correct
+ * -sorbo.
+ */
+ /* need to bootstrap */
+ if (hctx->ccid2hctx_rpdupack == -1) {
+ hctx->ccid2hctx_rpdupack = 0;
+ hctx->ccid2hctx_rpseq = seqno;
+ } else {
+ /* check if packet is consecutive */
+ if (dccp_delta_seqno(hctx->ccid2hctx_rpseq, seqno) == 1)
+ hctx->ccid2hctx_rpseq = seqno;
+ /* it's a later packet */
+ else if (after48(seqno, hctx->ccid2hctx_rpseq)) {
+ hctx->ccid2hctx_rpdupack++;
+
+ /* check if we got enough dupacks */
+ if (hctx->ccid2hctx_rpdupack >= NUMDUPACK) {
+ hctx->ccid2hctx_rpdupack = -1; /* XXX lame */
+ hctx->ccid2hctx_rpseq = 0;
+
+ ccid2_change_l_ack_ratio(sk, 2 * dp->dccps_l_ack_ratio);
+ }
+ }
+ }
+
+ /* check forward path congestion */
+ /* still didn't send out new data packets */
+ if (hctx->ccid2hctx_seqh == hctx->ccid2hctx_seqt)
+ return;
+
+ switch (DCCP_SKB_CB(skb)->dccpd_type) {
+ case DCCP_PKT_ACK:
+ case DCCP_PKT_DATAACK:
+ break;
+ default:
+ return;
+ }
+
+ ackno = DCCP_SKB_CB(skb)->dccpd_ack_seq;
+ if (after48(ackno, hctx->ccid2hctx_high_ack))
+ hctx->ccid2hctx_high_ack = ackno;
+
+ seqp = hctx->ccid2hctx_seqt;
+ while (before48(seqp->ccid2s_seq, ackno)) {
+ seqp = seqp->ccid2s_next;
+ if (seqp == hctx->ccid2hctx_seqh) {
+ seqp = hctx->ccid2hctx_seqh->ccid2s_prev;
+ break;
+ }
+ }
+
+ /*
+ * In slow-start, cwnd can increase up to a maximum of Ack Ratio/2
+ * packets per acknowledgement. Rounding up avoids that cwnd is not
+ * advanced when Ack Ratio is 1 and gives a slight edge otherwise.
+ */
+ if (hctx->ccid2hctx_cwnd < hctx->ccid2hctx_ssthresh)
+ maxincr = DIV_ROUND_UP(dp->dccps_l_ack_ratio, 2);
+
+ /* go through all ack vectors */
+ while ((offset = ccid2_ackvector(sk, skb, offset,
+ &vector, &veclen)) != -1) {
+ /* go through this ack vector */
+ while (veclen--) {
+ const u8 rl = *vector & DCCP_ACKVEC_LEN_MASK;
+ u64 ackno_end_rl = SUB48(ackno, rl);
+
+ ccid2_pr_debug("ackvec start:%llu end:%llu\n",
+ (unsigned long long)ackno,
+ (unsigned long long)ackno_end_rl);
+ /* if the seqno we are analyzing is larger than the
+ * current ackno, then move towards the tail of our
+ * seqnos.
+ */
+ while (after48(seqp->ccid2s_seq, ackno)) {
+ if (seqp == hctx->ccid2hctx_seqt) {
+ done = 1;
+ break;
+ }
+ seqp = seqp->ccid2s_prev;
+ }
+ if (done)
+ break;
+
+ /* check all seqnos in the range of the vector
+ * run length
+ */
+ while (between48(seqp->ccid2s_seq,ackno_end_rl,ackno)) {
+ const u8 state = *vector &
+ DCCP_ACKVEC_STATE_MASK;
+
+ /* new packet received or marked */
+ if (state != DCCP_ACKVEC_STATE_NOT_RECEIVED &&
+ !seqp->ccid2s_acked) {
+ if (state ==
+ DCCP_ACKVEC_STATE_ECN_MARKED) {
+ ccid2_congestion_event(sk,
+ seqp);
+ } else
+ ccid2_new_ack(sk, seqp,
+ &maxincr);
+
+ seqp->ccid2s_acked = 1;
+ ccid2_pr_debug("Got ack for %llu\n",
+ (unsigned long long)seqp->ccid2s_seq);
+ ccid2_hc_tx_dec_pipe(sk);
+ }
+ if (seqp == hctx->ccid2hctx_seqt) {
+ done = 1;
+ break;
+ }
+ seqp = seqp->ccid2s_prev;
+ }
+ if (done)
+ break;
+
+ ackno = SUB48(ackno_end_rl, 1);
+ vector++;
+ }
+ if (done)
+ break;
+ }
+
+ /* The state about what is acked should be correct now
+ * Check for NUMDUPACK
+ */
+ seqp = hctx->ccid2hctx_seqt;
+ while (before48(seqp->ccid2s_seq, hctx->ccid2hctx_high_ack)) {
+ seqp = seqp->ccid2s_next;
+ if (seqp == hctx->ccid2hctx_seqh) {
+ seqp = hctx->ccid2hctx_seqh->ccid2s_prev;
+ break;
+ }
+ }
+ done = 0;
+ while (1) {
+ if (seqp->ccid2s_acked) {
+ done++;
+ if (done == NUMDUPACK)
+ break;
+ }
+ if (seqp == hctx->ccid2hctx_seqt)
+ break;
+ seqp = seqp->ccid2s_prev;
+ }
+
+ /* If there are at least 3 acknowledgements, anything unacknowledged
+ * below the last sequence number is considered lost
+ */
+ if (done == NUMDUPACK) {
+ struct ccid2_seq *last_acked = seqp;
+
+ /* check for lost packets */
+ while (1) {
+ if (!seqp->ccid2s_acked) {
+ ccid2_pr_debug("Packet lost: %llu\n",
+ (unsigned long long)seqp->ccid2s_seq);
+ /* XXX need to traverse from tail -> head in
+ * order to detect multiple congestion events in
+ * one ack vector.
+ */
+ ccid2_congestion_event(sk, seqp);
+ ccid2_hc_tx_dec_pipe(sk);
+ }
+ if (seqp == hctx->ccid2hctx_seqt)
+ break;
+ seqp = seqp->ccid2s_prev;
+ }
+
+ hctx->ccid2hctx_seqt = last_acked;
+ }
+
+ /* trim acked packets in tail */
+ while (hctx->ccid2hctx_seqt != hctx->ccid2hctx_seqh) {
+ if (!hctx->ccid2hctx_seqt->ccid2s_acked)
+ break;
+
+ hctx->ccid2hctx_seqt = hctx->ccid2hctx_seqt->ccid2s_next;
+ }
+
+ ccid2_hc_tx_check_sanity(hctx);
+}
+
+static int ccid2_hc_tx_init(struct ccid *ccid, struct sock *sk)
+{
+ struct ccid2_hc_tx_sock *hctx = ccid_priv(ccid);
+ struct dccp_sock *dp = dccp_sk(sk);
+ u32 max_ratio;
+
+ /* RFC 4341, 5: initialise ssthresh to arbitrarily high (max) value */
+ hctx->ccid2hctx_ssthresh = ~0U;
+
+ /*
+ * RFC 4341, 5: "The cwnd parameter is initialized to at most four
+ * packets for new connections, following the rules from [RFC3390]".
+ * We need to convert the bytes of RFC3390 into the packets of RFC 4341.
+ */
+ hctx->ccid2hctx_cwnd = clamp(4380U / dp->dccps_mss_cache, 2U, 4U);
+
+ /* Make sure that Ack Ratio is enabled and within bounds. */
+ max_ratio = DIV_ROUND_UP(hctx->ccid2hctx_cwnd, 2);
+ if (dp->dccps_l_ack_ratio == 0 || dp->dccps_l_ack_ratio > max_ratio)
+ dp->dccps_l_ack_ratio = max_ratio;
+
+ /* XXX init ~ to window size... */
+ if (ccid2_hc_tx_alloc_seq(hctx))
+ return -ENOMEM;
+
+ hctx->ccid2hctx_rto = 3 * HZ;
+ ccid2_change_srtt(hctx, -1);
+ hctx->ccid2hctx_rttvar = -1;
+ hctx->ccid2hctx_rpdupack = -1;
+ hctx->ccid2hctx_last_cong = jiffies;
+ setup_timer(&hctx->ccid2hctx_rtotimer, ccid2_hc_tx_rto_expire,
+ (unsigned long)sk);
+
+ ccid2_hc_tx_check_sanity(hctx);
+ return 0;
+}
+
+static void ccid2_hc_tx_exit(struct sock *sk)
+{
+ struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
+ int i;
+
+ ccid2_hc_tx_kill_rto_timer(sk);
+
+ for (i = 0; i < hctx->ccid2hctx_seqbufc; i++)
+ kfree(hctx->ccid2hctx_seqbuf[i]);
+ hctx->ccid2hctx_seqbufc = 0;
+}
+
+static void ccid2_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb)
+{
+ const struct dccp_sock *dp = dccp_sk(sk);
+ struct ccid2_hc_rx_sock *hcrx = ccid2_hc_rx_sk(sk);
+
+ switch (DCCP_SKB_CB(skb)->dccpd_type) {
+ case DCCP_PKT_DATA:
+ case DCCP_PKT_DATAACK:
+ hcrx->ccid2hcrx_data++;
+ if (hcrx->ccid2hcrx_data >= dp->dccps_r_ack_ratio) {
+ dccp_send_ack(sk);
+ hcrx->ccid2hcrx_data = 0;
+ }
+ break;
+ }
+}
+
+static struct ccid_operations ccid2 = {
+ .ccid_id = DCCPC_CCID2,
+ .ccid_name = "TCP-like",
+ .ccid_owner = THIS_MODULE,
+ .ccid_hc_tx_obj_size = sizeof(struct ccid2_hc_tx_sock),
+ .ccid_hc_tx_init = ccid2_hc_tx_init,
+ .ccid_hc_tx_exit = ccid2_hc_tx_exit,
+ .ccid_hc_tx_send_packet = ccid2_hc_tx_send_packet,
+ .ccid_hc_tx_packet_sent = ccid2_hc_tx_packet_sent,
+ .ccid_hc_tx_packet_recv = ccid2_hc_tx_packet_recv,
+ .ccid_hc_rx_obj_size = sizeof(struct ccid2_hc_rx_sock),
+ .ccid_hc_rx_packet_recv = ccid2_hc_rx_packet_recv,
+};
+
+#ifdef CONFIG_IP_DCCP_CCID2_DEBUG
+module_param(ccid2_debug, bool, 0644);
+MODULE_PARM_DESC(ccid2_debug, "Enable debug messages");
+#endif
+
+static __init int ccid2_module_init(void)
+{
+ return ccid_register(&ccid2);
+}
+module_init(ccid2_module_init);
+
+static __exit void ccid2_module_exit(void)
+{
+ ccid_unregister(&ccid2);
+}
+module_exit(ccid2_module_exit);
+
+MODULE_AUTHOR("Andrea Bittau <a.bittau@cs.ucl.ac.uk>");
+MODULE_DESCRIPTION("DCCP TCP-Like (CCID2) CCID");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("net-dccp-ccid-2");
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