summaryrefslogtreecommitdiffstats
path: root/net/dccp/ackvec.c
diff options
context:
space:
mode:
Diffstat (limited to 'net/dccp/ackvec.c')
-rw-r--r--net/dccp/ackvec.c419
1 files changed, 419 insertions, 0 deletions
diff --git a/net/dccp/ackvec.c b/net/dccp/ackvec.c
new file mode 100644
index 00000000000..6530283eafc
--- /dev/null
+++ b/net/dccp/ackvec.c
@@ -0,0 +1,419 @@
+/*
+ * net/dccp/ackvec.c
+ *
+ * An implementation of the DCCP protocol
+ * Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
+ *
+ * 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; version 2 of the License;
+ */
+
+#include "ackvec.h"
+#include "dccp.h"
+
+#include <linux/dccp.h>
+#include <linux/skbuff.h>
+
+#include <net/sock.h>
+
+int dccp_insert_option_ackvec(struct sock *sk, struct sk_buff *skb)
+{
+ struct dccp_sock *dp = dccp_sk(sk);
+ struct dccp_ackvec *av = dp->dccps_hc_rx_ackvec;
+ int len = av->dccpav_vec_len + 2;
+ struct timeval now;
+ u32 elapsed_time;
+ unsigned char *to, *from;
+
+ dccp_timestamp(sk, &now);
+ elapsed_time = timeval_delta(&now, &av->dccpav_time) / 10;
+
+ if (elapsed_time != 0)
+ dccp_insert_option_elapsed_time(sk, skb, elapsed_time);
+
+ if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
+ return -1;
+
+ /*
+ * XXX: now we have just one ack vector sent record, so
+ * we have to wait for it to be cleared.
+ *
+ * Of course this is not acceptable, but this is just for
+ * basic testing now.
+ */
+ if (av->dccpav_ack_seqno != DCCP_MAX_SEQNO + 1)
+ return -1;
+
+ DCCP_SKB_CB(skb)->dccpd_opt_len += len;
+
+ to = skb_push(skb, len);
+ *to++ = DCCPO_ACK_VECTOR_0;
+ *to++ = len;
+
+ len = av->dccpav_vec_len;
+ from = av->dccpav_buf + av->dccpav_buf_head;
+
+ /* Check if buf_head wraps */
+ if (av->dccpav_buf_head + len > av->dccpav_vec_len) {
+ const u32 tailsize = (av->dccpav_vec_len - av->dccpav_buf_head);
+
+ memcpy(to, from, tailsize);
+ to += tailsize;
+ len -= tailsize;
+ from = av->dccpav_buf;
+ }
+
+ memcpy(to, from, len);
+ /*
+ * From draft-ietf-dccp-spec-11.txt:
+ *
+ * For each acknowledgement it sends, the HC-Receiver will add an
+ * acknowledgement record. ack_seqno will equal the HC-Receiver
+ * sequence number it used for the ack packet; ack_ptr will equal
+ * buf_head; ack_ackno will equal buf_ackno; and ack_nonce will
+ * equal buf_nonce.
+ *
+ * This implemention uses just one ack record for now.
+ */
+ av->dccpav_ack_seqno = DCCP_SKB_CB(skb)->dccpd_seq;
+ av->dccpav_ack_ptr = av->dccpav_buf_head;
+ av->dccpav_ack_ackno = av->dccpav_buf_ackno;
+ av->dccpav_ack_nonce = av->dccpav_buf_nonce;
+ av->dccpav_sent_len = av->dccpav_vec_len;
+
+ dccp_pr_debug("%sACK Vector 0, len=%d, ack_seqno=%llu, "
+ "ack_ackno=%llu\n",
+ debug_prefix, av->dccpav_sent_len,
+ (unsigned long long)av->dccpav_ack_seqno,
+ (unsigned long long)av->dccpav_ack_ackno);
+ return -1;
+}
+
+struct dccp_ackvec *dccp_ackvec_alloc(const unsigned int len,
+ const unsigned int __nocast priority)
+{
+ struct dccp_ackvec *av = kmalloc(sizeof(*av) + len, priority);
+
+ if (av != NULL) {
+ av->dccpav_buf_len = len;
+ av->dccpav_buf_head =
+ av->dccpav_buf_tail = av->dccpav_buf_len - 1;
+ av->dccpav_buf_ackno =
+ av->dccpav_ack_ackno = av->dccpav_ack_seqno = ~0LLU;
+ av->dccpav_buf_nonce = av->dccpav_buf_nonce = 0;
+ av->dccpav_ack_ptr = 0;
+ av->dccpav_time.tv_sec = 0;
+ av->dccpav_time.tv_usec = 0;
+ av->dccpav_sent_len = av->dccpav_vec_len = 0;
+ }
+
+ return av;
+}
+
+void dccp_ackvec_free(struct dccp_ackvec *av)
+{
+ kfree(av);
+}
+
+static inline u8 dccp_ackvec_state(const struct dccp_ackvec *av,
+ const unsigned int index)
+{
+ return av->dccpav_buf[index] & DCCP_ACKVEC_STATE_MASK;
+}
+
+static inline u8 dccp_ackvec_len(const struct dccp_ackvec *av,
+ const unsigned int index)
+{
+ return av->dccpav_buf[index] & DCCP_ACKVEC_LEN_MASK;
+}
+
+/*
+ * If several packets are missing, the HC-Receiver may prefer to enter multiple
+ * bytes with run length 0, rather than a single byte with a larger run length;
+ * this simplifies table updates if one of the missing packets arrives.
+ */
+static inline int dccp_ackvec_set_buf_head_state(struct dccp_ackvec *av,
+ const unsigned int packets,
+ const unsigned char state)
+{
+ unsigned int gap;
+ signed long new_head;
+
+ if (av->dccpav_vec_len + packets > av->dccpav_buf_len)
+ return -ENOBUFS;
+
+ gap = packets - 1;
+ new_head = av->dccpav_buf_head - packets;
+
+ if (new_head < 0) {
+ if (gap > 0) {
+ memset(av->dccpav_buf, DCCP_ACKVEC_STATE_NOT_RECEIVED,
+ gap + new_head + 1);
+ gap = -new_head;
+ }
+ new_head += av->dccpav_buf_len;
+ }
+
+ av->dccpav_buf_head = new_head;
+
+ if (gap > 0)
+ memset(av->dccpav_buf + av->dccpav_buf_head + 1,
+ DCCP_ACKVEC_STATE_NOT_RECEIVED, gap);
+
+ av->dccpav_buf[av->dccpav_buf_head] = state;
+ av->dccpav_vec_len += packets;
+ return 0;
+}
+
+/*
+ * Implements the draft-ietf-dccp-spec-11.txt Appendix A
+ */
+int dccp_ackvec_add(struct dccp_ackvec *av, const struct sock *sk,
+ const u64 ackno, const u8 state)
+{
+ /*
+ * Check at the right places if the buffer is full, if it is, tell the
+ * caller to start dropping packets till the HC-Sender acks our ACK
+ * vectors, when we will free up space in dccpav_buf.
+ *
+ * We may well decide to do buffer compression, etc, but for now lets
+ * just drop.
+ *
+ * From Appendix A:
+ *
+ * Of course, the circular buffer may overflow, either when the
+ * HC-Sender is sending data at a very high rate, when the
+ * HC-Receiver's acknowledgements are not reaching the HC-Sender,
+ * or when the HC-Sender is forgetting to acknowledge those acks
+ * (so the HC-Receiver is unable to clean up old state). In this
+ * case, the HC-Receiver should either compress the buffer (by
+ * increasing run lengths when possible), transfer its state to
+ * a larger buffer, or, as a last resort, drop all received
+ * packets, without processing them whatsoever, until its buffer
+ * shrinks again.
+ */
+
+ /* See if this is the first ackno being inserted */
+ if (av->dccpav_vec_len == 0) {
+ av->dccpav_buf[av->dccpav_buf_head] = state;
+ av->dccpav_vec_len = 1;
+ } else if (after48(ackno, av->dccpav_buf_ackno)) {
+ const u64 delta = dccp_delta_seqno(av->dccpav_buf_ackno,
+ ackno);
+
+ /*
+ * Look if the state of this packet is the same as the
+ * previous ackno and if so if we can bump the head len.
+ */
+ if (delta == 1 &&
+ dccp_ackvec_state(av, av->dccpav_buf_head) == state &&
+ (dccp_ackvec_len(av, av->dccpav_buf_head) <
+ DCCP_ACKVEC_LEN_MASK))
+ av->dccpav_buf[av->dccpav_buf_head]++;
+ else if (dccp_ackvec_set_buf_head_state(av, delta, state))
+ return -ENOBUFS;
+ } else {
+ /*
+ * A.1.2. Old Packets
+ *
+ * When a packet with Sequence Number S arrives, and
+ * S <= buf_ackno, the HC-Receiver will scan the table
+ * for the byte corresponding to S. (Indexing structures
+ * could reduce the complexity of this scan.)
+ */
+ u64 delta = dccp_delta_seqno(ackno, av->dccpav_buf_ackno);
+ unsigned int index = av->dccpav_buf_head;
+
+ while (1) {
+ const u8 len = dccp_ackvec_len(av, index);
+ const u8 state = dccp_ackvec_state(av, index);
+ /*
+ * valid packets not yet in dccpav_buf have a reserved
+ * entry, with a len equal to 0.
+ */
+ if (state == DCCP_ACKVEC_STATE_NOT_RECEIVED &&
+ len == 0 && delta == 0) { /* Found our
+ reserved seat! */
+ dccp_pr_debug("Found %llu reserved seat!\n",
+ (unsigned long long)ackno);
+ av->dccpav_buf[index] = state;
+ goto out;
+ }
+ /* len == 0 means one packet */
+ if (delta < len + 1)
+ goto out_duplicate;
+
+ delta -= len + 1;
+ if (++index == av->dccpav_buf_len)
+ index = 0;
+ }
+ }
+
+ av->dccpav_buf_ackno = ackno;
+ dccp_timestamp(sk, &av->dccpav_time);
+out:
+ dccp_pr_debug("");
+ return 0;
+
+out_duplicate:
+ /* Duplicate packet */
+ dccp_pr_debug("Received a dup or already considered lost "
+ "packet: %llu\n", (unsigned long long)ackno);
+ return -EILSEQ;
+}
+
+#ifdef CONFIG_IP_DCCP_DEBUG
+void dccp_ackvector_print(const u64 ackno, const unsigned char *vector, int len)
+{
+ if (!dccp_debug)
+ return;
+
+ printk("ACK vector len=%d, ackno=%llu |", len,
+ (unsigned long long)ackno);
+
+ while (len--) {
+ const u8 state = (*vector & DCCP_ACKVEC_STATE_MASK) >> 6;
+ const u8 rl = *vector & DCCP_ACKVEC_LEN_MASK;
+
+ printk("%d,%d|", state, rl);
+ ++vector;
+ }
+
+ printk("\n");
+}
+
+void dccp_ackvec_print(const struct dccp_ackvec *av)
+{
+ dccp_ackvector_print(av->dccpav_buf_ackno,
+ av->dccpav_buf + av->dccpav_buf_head,
+ av->dccpav_vec_len);
+}
+#endif
+
+static void dccp_ackvec_trow_away_ack_record(struct dccp_ackvec *av)
+{
+ /*
+ * As we're keeping track of the ack vector size (dccpav_vec_len) and
+ * the sent ack vector size (dccpav_sent_len) we don't need
+ * dccpav_buf_tail at all, but keep this code here as in the future
+ * we'll implement a vector of ack records, as suggested in
+ * draft-ietf-dccp-spec-11.txt Appendix A. -acme
+ */
+#if 0
+ av->dccpav_buf_tail = av->dccpav_ack_ptr + 1;
+ if (av->dccpav_buf_tail >= av->dccpav_vec_len)
+ av->dccpav_buf_tail -= av->dccpav_vec_len;
+#endif
+ av->dccpav_vec_len -= av->dccpav_sent_len;
+}
+
+void dccp_ackvec_check_rcv_ackno(struct dccp_ackvec *av, struct sock *sk,
+ const u64 ackno)
+{
+ /* Check if we actually sent an ACK vector */
+ if (av->dccpav_ack_seqno == DCCP_MAX_SEQNO + 1)
+ return;
+
+ if (ackno == av->dccpav_ack_seqno) {
+#ifdef CONFIG_IP_DCCP_DEBUG
+ struct dccp_sock *dp = dccp_sk(sk);
+ const char *debug_prefix = dp->dccps_role == DCCP_ROLE_CLIENT ?
+ "CLIENT rx ack: " : "server rx ack: ";
+#endif
+ dccp_pr_debug("%sACK packet 0, len=%d, ack_seqno=%llu, "
+ "ack_ackno=%llu, ACKED!\n",
+ debug_prefix, 1,
+ (unsigned long long)av->dccpav_ack_seqno,
+ (unsigned long long)av->dccpav_ack_ackno);
+ dccp_ackvec_trow_away_ack_record(av);
+ av->dccpav_ack_seqno = DCCP_MAX_SEQNO + 1;
+ }
+}
+
+static void dccp_ackvec_check_rcv_ackvector(struct dccp_ackvec *av,
+ struct sock *sk, u64 ackno,
+ const unsigned char len,
+ const unsigned char *vector)
+{
+ unsigned char i;
+
+ /* Check if we actually sent an ACK vector */
+ if (av->dccpav_ack_seqno == DCCP_MAX_SEQNO + 1)
+ return;
+ /*
+ * We're in the receiver half connection, so if the received an ACK
+ * vector ackno (e.g. 50) before dccpav_ack_seqno (e.g. 52), we're
+ * not interested.
+ *
+ * Extra explanation with example:
+ *
+ * if we received an ACK vector with ackno 50, it can only be acking
+ * 50, 49, 48, etc, not 52 (the seqno for the ACK vector we sent).
+ */
+ /* dccp_pr_debug("is %llu < %llu? ", ackno, av->dccpav_ack_seqno); */
+ if (before48(ackno, av->dccpav_ack_seqno)) {
+ /* dccp_pr_debug_cat("yes\n"); */
+ return;
+ }
+ /* dccp_pr_debug_cat("no\n"); */
+
+ i = len;
+ while (i--) {
+ const u8 rl = *vector & DCCP_ACKVEC_LEN_MASK;
+ u64 ackno_end_rl;
+
+ dccp_set_seqno(&ackno_end_rl, ackno - rl);
+
+ /*
+ * dccp_pr_debug("is %llu <= %llu <= %llu? ", ackno_end_rl,
+ * av->dccpav_ack_seqno, ackno);
+ */
+ if (between48(av->dccpav_ack_seqno, ackno_end_rl, ackno)) {
+ const u8 state = (*vector &
+ DCCP_ACKVEC_STATE_MASK) >> 6;
+ /* dccp_pr_debug_cat("yes\n"); */
+
+ if (state != DCCP_ACKVEC_STATE_NOT_RECEIVED) {
+#ifdef CONFIG_IP_DCCP_DEBUG
+ struct dccp_sock *dp = dccp_sk(sk);
+ const char *debug_prefix =
+ dp->dccps_role == DCCP_ROLE_CLIENT ?
+ "CLIENT rx ack: " : "server rx ack: ";
+#endif
+ dccp_pr_debug("%sACK vector 0, len=%d, "
+ "ack_seqno=%llu, ack_ackno=%llu, "
+ "ACKED!\n",
+ debug_prefix, len,
+ (unsigned long long)
+ av->dccpav_ack_seqno,
+ (unsigned long long)
+ av->dccpav_ack_ackno);
+ dccp_ackvec_trow_away_ack_record(av);
+ }
+ /*
+ * If dccpav_ack_seqno was not received, no problem
+ * we'll send another ACK vector.
+ */
+ av->dccpav_ack_seqno = DCCP_MAX_SEQNO + 1;
+ break;
+ }
+ /* dccp_pr_debug_cat("no\n"); */
+
+ dccp_set_seqno(&ackno, ackno_end_rl - 1);
+ ++vector;
+ }
+}
+
+int dccp_ackvec_parse(struct sock *sk, const struct sk_buff *skb,
+ const u8 opt, const u8 *value, const u8 len)
+{
+ if (len > DCCP_MAX_ACKVEC_LEN)
+ return -1;
+
+ /* dccp_ackvector_print(DCCP_SKB_CB(skb)->dccpd_ack_seq, value, len); */
+ dccp_ackvec_check_rcv_ackvector(dccp_sk(sk)->dccps_hc_rx_ackvec, sk,
+ DCCP_SKB_CB(skb)->dccpd_ack_seq,
+ len, value);
+ return 0;
+}
generated by cgit v1.2.3-70-g09d2 (git 2.46.0) at 2024-12-28 07:45:23 +0000