Subversion Repositories test_project

/*

 *  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/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;

static struct dccp_ackvec_record *dccp_ackvec_record_new(void)

{

        struct dccp_ackvec_record *avr =

                        kmem_cache_alloc(dccp_ackvec_record_slab, GFP_ATOMIC);

        if (avr != NULL)

                INIT_LIST_HEAD(&avr->dccpavr_node);

        return avr;

}

static void dccp_ackvec_record_delete(struct dccp_ackvec_record *avr)

{

        if (unlikely(avr == NULL))

                return;

        /* Check if deleting a linked record */

        WARN_ON(!list_empty(&avr->dccpavr_node));

        kmem_cache_free(dccp_ackvec_record_slab, avr);

}

static void dccp_ackvec_insert_avr(struct dccp_ackvec *av,

                                   struct dccp_ackvec_record *avr)

{

        /*

         * AVRs are sorted by seqno. Since we are sending them in order, we

         * just add the AVR at the head of the list.

         * -sorbo.

         */

        if (!list_empty(&av->dccpav_records)) {

                const struct dccp_ackvec_record *head =

                                        list_entry(av->dccpav_records.next,

                                                   struct dccp_ackvec_record,

                                                   dccpavr_node);

                BUG_ON(before48(avr->dccpavr_ack_seqno,

                                head->dccpavr_ack_seqno));

        }

        list_add(&avr->dccpavr_node, &av->dccpav_records);

}

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;

        /* Figure out how many options do we need to represent the ackvec */

        const u16 nr_opts = DIV_ROUND_UP(av->dccpav_vec_len,

                                         DCCP_MAX_ACKVEC_OPT_LEN);

        u16 len = av->dccpav_vec_len + 2 * nr_opts, i;

        u32 elapsed_time;

        const unsigned char *tail, *from;

        unsigned char *to;

        struct dccp_ackvec_record *avr;

        suseconds_t delta;

        if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)

                return -1;

        delta = ktime_us_delta(ktime_get_real(), av->dccpav_time);

        elapsed_time = delta / 10;

        if (elapsed_time != 0 &&

            dccp_insert_option_elapsed_time(sk, skb, elapsed_time))

                return -1;

        avr = dccp_ackvec_record_new();

        if (avr == NULL)

                return -1;

        DCCP_SKB_CB(skb)->dccpd_opt_len += len;

        to   = skb_push(skb, len);

        len  = av->dccpav_vec_len;

        from = av->dccpav_buf + av->dccpav_buf_head;

        tail = av->dccpav_buf + DCCP_MAX_ACKVEC_LEN;

        for (i = 0; i < nr_opts; ++i) {

                int copylen = len;

                if (len > DCCP_MAX_ACKVEC_OPT_LEN)

                        copylen = DCCP_MAX_ACKVEC_OPT_LEN;

                *to++ = DCCPO_ACK_VECTOR_0;

                *to++ = copylen + 2;

                /* Check if buf_head wraps */

                if (from + copylen > tail) {

                        const u16 tailsize = tail - from;

                        memcpy(to, from, tailsize);

                        to      += tailsize;

                        len     -= tailsize;

                        copylen -= tailsize;

                        from    = av->dccpav_buf;

                }

                memcpy(to, from, copylen);

                from += copylen;

                to   += copylen;

                len  -= copylen;

        }

        /*

         *      From RFC 4340, A.2:

         *

         *      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.

         */

        avr->dccpavr_ack_seqno = DCCP_SKB_CB(skb)->dccpd_seq;

        avr->dccpavr_ack_ptr   = av->dccpav_buf_head;

        avr->dccpavr_ack_ackno = av->dccpav_buf_ackno;

        avr->dccpavr_ack_nonce = av->dccpav_buf_nonce;

        avr->dccpavr_sent_len  = av->dccpav_vec_len;

        dccp_ackvec_insert_avr(av, avr);

        dccp_pr_debug("%s ACK Vector 0, len=%d, ack_seqno=%llu, "

                      "ack_ackno=%llu\n",

                      dccp_role(sk), avr->dccpavr_sent_len,

                      (unsigned long long)avr->dccpavr_ack_seqno,

                      (unsigned long long)avr->dccpavr_ack_ackno);

        return 0;

}

struct dccp_ackvec *dccp_ackvec_alloc(const gfp_t priority)

{

        struct dccp_ackvec *av = kmem_cache_alloc(dccp_ackvec_slab, priority);

        if (av != NULL) {

                av->dccpav_buf_head     = DCCP_MAX_ACKVEC_LEN - 1;

                av->dccpav_buf_ackno    = UINT48_MAX + 1;

                av->dccpav_buf_nonce = av->dccpav_buf_nonce = 0;

                av->dccpav_time      = ktime_set(0, 0);

                av->dccpav_vec_len      = 0;

                INIT_LIST_HEAD(&av->dccpav_records);

        }

        return av;

}

void dccp_ackvec_free(struct dccp_ackvec *av)

{

        if (unlikely(av == NULL))

                return;

        if (!list_empty(&av->dccpav_records)) {

                struct dccp_ackvec_record *avr, *next;

                list_for_each_entry_safe(avr, next, &av->dccpav_records,

                                         dccpavr_node) {

                        list_del_init(&avr->dccpavr_node);

                        dccp_ackvec_record_delete(avr);

                }

        }

        kmem_cache_free(dccp_ackvec_slab, av);

}

static inline u8 dccp_ackvec_state(const struct dccp_ackvec *av,

                                   const u32 index)

{

        return av->dccpav_buf[index] & DCCP_ACKVEC_STATE_MASK;

}

static inline u8 dccp_ackvec_len(const struct dccp_ackvec *av,

                                 const u32 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;

        long new_head;

        if (av->dccpav_vec_len + packets > DCCP_MAX_ACKVEC_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 += DCCP_MAX_ACKVEC_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 RFC 4340, 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.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->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 <= 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->dccpav_buf_ackno);

                u32 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 == DCCP_MAX_ACKVEC_LEN)

                                index = 0;

                }

        }

        av->dccpav_buf_ackno = ackno;

        av->dccpav_time = ktime_get_real();

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;

}

#ifdef CONFIG_IP_DCCP_DEBUG

void dccp_ackvector_print(const u64 ackno, const unsigned char *vector, int len)

{

        dccp_pr_debug_cat("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;

                dccp_pr_debug_cat("%d,%d|", state, rl);

                ++vector;

        }

        dccp_pr_debug_cat("\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_throw_record(struct dccp_ackvec *av,

                                     struct dccp_ackvec_record *avr)

{

        struct dccp_ackvec_record *next;

        /* sort out vector length */

        if (av->dccpav_buf_head <= avr->dccpavr_ack_ptr)

                av->dccpav_vec_len = avr->dccpavr_ack_ptr - av->dccpav_buf_head;

        else

                av->dccpav_vec_len = DCCP_MAX_ACKVEC_LEN - 1

                                     - av->dccpav_buf_head

                                     + avr->dccpavr_ack_ptr;

        /* free records */

        list_for_each_entry_safe_from(avr, next, &av->dccpav_records,

                                      dccpavr_node) {

                list_del_init(&avr->dccpavr_node);

                dccp_ackvec_record_delete(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->dccpav_records, dccpavr_node) {

                if (ackno == avr->dccpavr_ack_seqno) {

                        dccp_pr_debug("%s ACK packet 0, len=%d, ack_seqno=%llu, "

                                      "ack_ackno=%llu, ACKED!\n",

                                      dccp_role(sk), 1,

                                      (unsigned long long)avr->dccpavr_ack_seqno,

                                      (unsigned long long)avr->dccpavr_ack_ackno);

                        dccp_ackvec_throw_record(av, avr);

                        break;

                } else if (avr->dccpavr_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->dccpav_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->dccpav_records.next, struct dccp_ackvec_record,

                         dccpavr_node);

        while (i--) {

                const u8 rl = *vector & DCCP_ACKVEC_LEN_MASK;

                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->dccpav_records,

                                         dccpavr_node) {

                        if (!after48(avr->dccpavr_ack_seqno, *ackno))

                                goto found;

                }

                /* End of the dccpav_records list, not found, exit */

                break;

found:

                if (between48(avr->dccpavr_ack_seqno, ackno_end_rl, *ackno)) {

                        const u8 state = *vector & DCCP_ACKVEC_STATE_MASK;

                        if (state != DCCP_ACKVEC_STATE_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->dccpavr_ack_seqno,

                                              (unsigned long long)

                                              avr->dccpavr_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_MAX_ACKVEC_OPT_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,

                                        ackno, len, value);

        return 0;

}

int __init dccp_ackvec_init(void)

{

        dccp_ackvec_slab = kmem_cache_create("dccp_ackvec",

                                             sizeof(struct dccp_ackvec), 0,

                                             SLAB_HWCACHE_ALIGN, NULL);

        if (dccp_ackvec_slab == NULL)

                goto out_err;

        dccp_ackvec_record_slab =

                        kmem_cache_create("dccp_ackvec_record",

                                          sizeof(struct dccp_ackvec_record),

                                          0, SLAB_HWCACHE_ALIGN, NULL);

        if (dccp_ackvec_record_slab == NULL)

                goto out_destroy_slab;

        return 0;

out_destroy_slab:

        kmem_cache_destroy(dccp_ackvec_slab);

        dccp_ackvec_slab = NULL;

out_err:

        DCCP_CRIT("Unable to create Ack Vector slab cache");

        return -ENOBUFS;

}

void dccp_ackvec_exit(void)

{

        if (dccp_ackvec_slab != NULL) {

                kmem_cache_destroy(dccp_ackvec_slab);

                dccp_ackvec_slab = NULL;

        }

        if (dccp_ackvec_record_slab != NULL) {

                kmem_cache_destroy(dccp_ackvec_record_slab);

                dccp_ackvec_record_slab = NULL;

        }

}