diff options
author | Arnaldo Carvalho de Melo <acme@mandriva.com> | 2005-09-18 00:17:51 -0700 |
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committer | David S. Miller <davem@davemloft.net> | 2005-09-18 00:17:51 -0700 |
commit | ae31c3399d17b1f7bc1742724f70476b5417744f (patch) | |
tree | c34099afb228936672e6e589f0af7d81f1f62443 /net/dccp/ackvec.c | |
parent | 21f130a2370ba837cdfc5204ebe52e7c664fec3d (diff) | |
download | linux-ae31c3399d17b1f7bc1742724f70476b5417744f.tar.bz2 |
[DCCP]: Move the ack vector code to net/dccp/ackvec.[ch]
Isolating it, that will be used when we introduce a CCID2 (TCP-Like)
implementation.
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/dccp/ackvec.c')
-rw-r--r-- | net/dccp/ackvec.c | 419 |
1 files changed, 419 insertions, 0 deletions
diff --git a/net/dccp/ackvec.c b/net/dccp/ackvec.c new file mode 100644 index 000000000000..6530283eafca --- /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; +} |