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