* 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/init.h>
-#include <linux/errno.h>
#include <linux/kernel.h>
-#include <linux/skbuff.h>
#include <linux/slab.h>
-#include <net/sock.h>
-
static struct kmem_cache *dccp_ackvec_slab;
static struct kmem_cache *dccp_ackvec_record_slab;
}
}
-/*
- * 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)
-{
- long gap;
- long new_head;
-
- if (av->av_vec_len + packets > DCCPAV_MAX_ACKVEC_LEN)
- return -ENOBUFS;
-
- gap = packets - 1;
- new_head = av->av_buf_head - packets;
-
- if (new_head < 0) {
- if (gap > 0) {
- memset(av->av_buf, DCCPAV_NOT_RECEIVED,
- gap + new_head + 1);
- gap = -new_head;
- }
- new_head += DCCPAV_MAX_ACKVEC_LEN;
- }
-
- av->av_buf_head = new_head;
-
- if (gap > 0)
- memset(av->av_buf + av->av_buf_head + 1,
- DCCPAV_NOT_RECEIVED, gap);
-
- av->av_buf[av->av_buf_head] = state;
- av->av_vec_len += packets;
- return 0;
-}
-
-/*
- * Implements the RFC 4340, Appendix A
- */
-int dccp_ackvec_add(struct dccp_ackvec *av, const struct sock *sk,
- const u64 ackno, const u8 state)
-{
- u8 *cur_head = av->av_buf + av->av_buf_head,
- *buf_end = av->av_buf + DCCPAV_MAX_ACKVEC_LEN;
- /*
- * 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 av_buf.
- *
- * We may well decide to do buffer compression, etc, but for now lets
- * just drop.
- *
- * From Appendix A.1.1 (`New Packets'):
- *
- * 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->av_vec_len == 0) {
- *cur_head = state;
- av->av_vec_len = 1;
- } else if (after48(ackno, av->av_buf_ackno)) {
- const u64 delta = dccp_delta_seqno(av->av_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(cur_head) == state &&
- dccp_ackvec_runlen(cur_head) < DCCPAV_MAX_RUNLEN)
- *cur_head += 1;
- 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 <= buf_ackno
- * arrives, 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->av_buf_ackno);
-
- while (1) {
- const u8 len = dccp_ackvec_runlen(cur_head);
- /*
- * valid packets not yet in av_buf have a reserved
- * entry, with a len equal to 0.
- */
- if (*cur_head == DCCPAV_NOT_RECEIVED && delta == 0) {
- dccp_pr_debug("Found %llu reserved seat!\n",
- (unsigned long long)ackno);
- *cur_head = state;
- goto out;
- }
- /* len == 0 means one packet */
- if (delta < len + 1)
- goto out_duplicate;
-
- delta -= len + 1;
- if (++cur_head == buf_end)
- cur_head = av->av_buf;
- }
- }
-
- av->av_buf_ackno = ackno;
-out:
- 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;
-}
-
-static void dccp_ackvec_throw_record(struct dccp_ackvec *av,
- struct dccp_ackvec_record *avr)
-{
- struct dccp_ackvec_record *next;
-
- /* sort out vector length */
- if (av->av_buf_head <= avr->avr_ack_ptr)
- av->av_vec_len = avr->avr_ack_ptr - av->av_buf_head;
- else
- av->av_vec_len = DCCPAV_MAX_ACKVEC_LEN - 1 -
- av->av_buf_head + avr->avr_ack_ptr;
-
- /* free records */
- list_for_each_entry_safe_from(avr, next, &av->av_records, avr_node) {
- list_del(&avr->avr_node);
- kmem_cache_free(dccp_ackvec_record_slab, avr);
- }
-}
-
-void dccp_ackvec_check_rcv_ackno(struct dccp_ackvec *av, struct sock *sk,
- const u64 ackno)
-{
- struct dccp_ackvec_record *avr;
-
- /*
- * If we traverse backwards, it should be faster when we have large
- * windows. We will be receiving ACKs for stuff we sent a while back
- * -sorbo.
- */
- list_for_each_entry_reverse(avr, &av->av_records, avr_node) {
- if (ackno == avr->avr_ack_seqno) {
- dccp_pr_debug("%s ACK packet 0, len=%d, ack_seqno=%llu, "
- "ack_ackno=%llu, ACKED!\n",
- dccp_role(sk), avr->avr_ack_runlen,
- (unsigned long long)avr->avr_ack_seqno,
- (unsigned long long)avr->avr_ack_ackno);
- dccp_ackvec_throw_record(av, avr);
- break;
- } else if (avr->avr_ack_seqno > ackno)
- break; /* old news */
- }
-}
-
-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;
- struct dccp_ackvec_record *avr;
-
- /* Check if we actually sent an ACK vector */
- if (list_empty(&av->av_records))
- return;
-
- i = len;
- /*
- * XXX
- * I think it might be more efficient to work backwards. See comment on
- * rcv_ackno. -sorbo.
- */
- avr = list_entry(av->av_records.next, struct dccp_ackvec_record, avr_node);
- while (i--) {
- const u8 rl = dccp_ackvec_runlen(vector);
- u64 ackno_end_rl;
-
- dccp_set_seqno(&ackno_end_rl, *ackno - rl);
-
- /*
- * If our AVR sequence number is greater than the ack, go
- * forward in the AVR list until it is not so.
- */
- list_for_each_entry_from(avr, &av->av_records, avr_node) {
- if (!after48(avr->avr_ack_seqno, *ackno))
- goto found;
- }
- /* End of the av_records list, not found, exit */
- break;
-found:
- if (between48(avr->avr_ack_seqno, ackno_end_rl, *ackno)) {
- if (dccp_ackvec_state(vector) != DCCPAV_NOT_RECEIVED) {
- dccp_pr_debug("%s ACK vector 0, len=%d, "
- "ack_seqno=%llu, ack_ackno=%llu, "
- "ACKED!\n",
- dccp_role(sk), len,
- (unsigned long long)
- avr->avr_ack_seqno,
- (unsigned long long)
- avr->avr_ack_ackno);
- dccp_ackvec_throw_record(av, avr);
- break;
- }
- /*
- * If it wasn't received, continue scanning... we might
- * find another one.
- */
- }
-
- dccp_set_seqno(ackno, ackno_end_rl - 1);
- ++vector;
- }
-}
-
-int dccp_ackvec_parse(struct sock *sk, const struct sk_buff *skb,
- u64 *ackno, const u8 opt, const u8 *value, const u8 len)
-{
- if (len > DCCP_SINGLE_OPT_MAXLEN)
- 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,
- ackno, len, value);
- return 0;
-}
-
/**
* dccp_ackvec_clear_state - Perform house-keeping / garbage-collection
* This routine is called when the peer acknowledges the receipt of Ack Vectors
projects / mirror_ubuntu-kernels.git / commitdiff