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dccp ccid-2: Separate option parsing from CCID processing
This patch replaces an almost identical replication of code: large parts
of dccp_parse_options() re-appeared as ccid2_ackvector() in ccid2.c.
Apart from the duplication, this caused two more problems:
1. CCIDs should not need to be concerned with parsing header options;
2. one can not assume that Ack Vectors appear as a contiguous area within an
skb, it is legal to insert other options and/or padding in between. The
current code would throw an error and stop reading in such a case.
The patch provides a new data structure and associated list housekeeping.
Only small changes were necessary to integrate with CCID-2: data structure
initialisation, adapt list traversal routine, and add call to the provided
cleanup routine.
The latter also lead to fixing the following BUG: CCID-2 so far ignored
Ack Vectors on all packets other than Ack/DataAck, which is incorrect,
since Ack Vectors can be present on any packet that has an Ack field.
Details:
--------
* received Ack Vectors are parsed by dccp_parse_options() alone, which passes
the result on to the CCID-specific routine ccid_hc_tx_parse_options();
* CCIDs interested in using/decoding Ack Vector information will add code
to fetch parsed Ack Vectors via this interface;
* a data structure, `struct dccp_ackvec_parsed' is provided as interface;
* this structure arranges Ack Vectors of the same skb into a FIFO order;
* a doubly-linked list is used to keep the required FIFO code small.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
This commit is contained in:
Gerrit Renker
parent
5a577b488f
commit
c8bf462bc5
@ -343,6 +343,34 @@ free_records:
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}
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}
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/*
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* Routines to keep track of Ack Vectors received in an skb
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*/
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int dccp_ackvec_parsed_add(struct list_head *head, u8 *vec, u8 len, u8 nonce)
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{
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struct dccp_ackvec_parsed *new = kmalloc(sizeof(*new), GFP_ATOMIC);
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if (new == NULL)
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return -ENOBUFS;
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new->vec = vec;
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new->len = len;
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new->nonce = nonce;
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list_add_tail(&new->node, head);
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return 0;
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}
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EXPORT_SYMBOL_GPL(dccp_ackvec_parsed_add);
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void dccp_ackvec_parsed_cleanup(struct list_head *parsed_chunks)
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{
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struct dccp_ackvec_parsed *cur, *next;
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list_for_each_entry_safe(cur, next, parsed_chunks, node)
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kfree(cur);
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INIT_LIST_HEAD(parsed_chunks);
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}
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EXPORT_SYMBOL_GPL(dccp_ackvec_parsed_cleanup);
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int __init dccp_ackvec_init(void)
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{
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dccp_ackvec_slab = kmem_cache_create("dccp_ackvec",
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@ -114,4 +114,23 @@ static inline bool dccp_ackvec_is_empty(const struct dccp_ackvec *av)
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{
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return av->av_overflow == 0 && av->av_buf_head == av->av_buf_tail;
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}
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/**
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* struct dccp_ackvec_parsed - Record offsets of Ack Vectors in skb
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* @vec: start of vector (offset into skb)
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* @len: length of @vec
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* @nonce: whether @vec had an ECN nonce of 0 or 1
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* @node: FIFO - arranged in descending order of ack_ackno
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* This structure is used by CCIDs to access Ack Vectors in a received skb.
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*/
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struct dccp_ackvec_parsed {
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u8 *vec,
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len,
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nonce:1;
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struct list_head node;
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};
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extern int dccp_ackvec_parsed_add(struct list_head *head,
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u8 *vec, u8 len, u8 nonce);
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extern void dccp_ackvec_parsed_cleanup(struct list_head *parsed_chunks);
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#endif /* _ACKVEC_H */
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@ -317,68 +317,6 @@ static void ccid2_hc_tx_packet_sent(struct sock *sk, unsigned int len)
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#endif
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}
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/* XXX Lame code duplication!
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* returns -1 if none was found.
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* else returns the next offset to use in the function call.
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*/
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static int ccid2_ackvector(struct sock *sk, struct sk_buff *skb, int offset,
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unsigned char **vec, unsigned char *veclen)
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{
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const struct dccp_hdr *dh = dccp_hdr(skb);
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unsigned char *options = (unsigned char *)dh + dccp_hdr_len(skb);
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unsigned char *opt_ptr;
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const unsigned char *opt_end = (unsigned char *)dh +
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(dh->dccph_doff * 4);
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unsigned char opt, len;
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unsigned char *value;
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BUG_ON(offset < 0);
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options += offset;
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opt_ptr = options;
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if (opt_ptr >= opt_end)
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return -1;
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while (opt_ptr != opt_end) {
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opt = *opt_ptr++;
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len = 0;
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value = NULL;
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/* Check if this isn't a single byte option */
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if (opt > DCCPO_MAX_RESERVED) {
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if (opt_ptr == opt_end)
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goto out_invalid_option;
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len = *opt_ptr++;
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if (len < 3)
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goto out_invalid_option;
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/*
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* Remove the type and len fields, leaving
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* just the value size
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*/
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len -= 2;
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value = opt_ptr;
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opt_ptr += len;
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if (opt_ptr > opt_end)
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goto out_invalid_option;
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}
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switch (opt) {
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case DCCPO_ACK_VECTOR_0:
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case DCCPO_ACK_VECTOR_1:
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*vec = value;
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*veclen = len;
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return offset + (opt_ptr - options);
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}
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}
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return -1;
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out_invalid_option:
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DCCP_BUG("Invalid option - this should not happen (previous parsing)!");
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return -1;
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}
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static void ccid2_hc_tx_kill_rto_timer(struct sock *sk)
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{
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struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
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@ -499,15 +437,27 @@ static void ccid2_congestion_event(struct sock *sk, struct ccid2_seq *seqp)
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ccid2_change_l_ack_ratio(sk, hctx->cwnd);
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}
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static int ccid2_hc_tx_parse_options(struct sock *sk, u8 packet_type,
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u8 option, u8 *optval, u8 optlen)
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{
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struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
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switch (option) {
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case DCCPO_ACK_VECTOR_0:
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case DCCPO_ACK_VECTOR_1:
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return dccp_ackvec_parsed_add(&hctx->av_chunks, optval, optlen,
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option - DCCPO_ACK_VECTOR_0);
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}
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return 0;
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}
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static void ccid2_hc_tx_packet_recv(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 ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
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struct dccp_ackvec_parsed *avp;
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u64 ackno, seqno;
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struct ccid2_seq *seqp;
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unsigned char *vector;
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unsigned char veclen;
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int offset = 0;
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int done = 0;
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unsigned int maxincr = 0;
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@ -542,17 +492,12 @@ static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
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}
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/* check forward path congestion */
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/* still didn't send out new data packets */
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if (hctx->seqh == hctx->seqt)
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if (dccp_packet_without_ack(skb))
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return;
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switch (DCCP_SKB_CB(skb)->dccpd_type) {
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case DCCP_PKT_ACK:
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case DCCP_PKT_DATAACK:
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break;
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default:
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return;
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}
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/* still didn't send out new data packets */
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if (hctx->seqh == hctx->seqt)
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goto done;
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ackno = DCCP_SKB_CB(skb)->dccpd_ack_seq;
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if (after48(ackno, hctx->high_ack))
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@ -576,15 +521,16 @@ static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
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maxincr = DIV_ROUND_UP(dp->dccps_l_ack_ratio, 2);
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/* go through all ack vectors */
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while ((offset = ccid2_ackvector(sk, skb, offset,
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&vector, &veclen)) != -1) {
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list_for_each_entry(avp, &hctx->av_chunks, node) {
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/* go through this ack vector */
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while (veclen--) {
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u64 ackno_end_rl = SUB48(ackno, dccp_ackvec_runlen(vector));
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for (; avp->len--; avp->vec++) {
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u64 ackno_end_rl = SUB48(ackno,
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dccp_ackvec_runlen(avp->vec));
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ccid2_pr_debug("ackvec start:%llu end:%llu\n",
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ccid2_pr_debug("ackvec %llu |%u,%u|\n",
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(unsigned long long)ackno,
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(unsigned long long)ackno_end_rl);
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dccp_ackvec_state(avp->vec) >> 6,
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dccp_ackvec_runlen(avp->vec));
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/* if the seqno we are analyzing is larger than the
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* current ackno, then move towards the tail of our
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* seqnos.
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@ -603,7 +549,7 @@ static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
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* run length
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*/
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while (between48(seqp->ccid2s_seq,ackno_end_rl,ackno)) {
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const u8 state = dccp_ackvec_state(vector);
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const u8 state = dccp_ackvec_state(avp->vec);
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/* new packet received or marked */
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if (state != DCCPAV_NOT_RECEIVED &&
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@ -630,7 +576,6 @@ static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
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break;
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ackno = SUB48(ackno_end_rl, 1);
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vector++;
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}
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if (done)
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break;
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@ -694,6 +639,8 @@ static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
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}
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ccid2_hc_tx_check_sanity(hctx);
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done:
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dccp_ackvec_parsed_cleanup(&hctx->av_chunks);
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}
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static int ccid2_hc_tx_init(struct ccid *ccid, struct sock *sk)
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@ -727,6 +674,7 @@ static int ccid2_hc_tx_init(struct ccid *ccid, struct sock *sk)
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hctx->rpdupack = -1;
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hctx->last_cong = jiffies;
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setup_timer(&hctx->rtotimer, ccid2_hc_tx_rto_expire, (unsigned long)sk);
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INIT_LIST_HEAD(&hctx->av_chunks);
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ccid2_hc_tx_check_sanity(hctx);
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return 0;
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@ -762,17 +710,18 @@ static void ccid2_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb)
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}
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static struct ccid_operations ccid2 = {
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.ccid_id = DCCPC_CCID2,
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.ccid_name = "TCP-like",
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.ccid_owner = THIS_MODULE,
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.ccid_hc_tx_obj_size = sizeof(struct ccid2_hc_tx_sock),
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.ccid_hc_tx_init = ccid2_hc_tx_init,
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.ccid_hc_tx_exit = ccid2_hc_tx_exit,
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.ccid_hc_tx_send_packet = ccid2_hc_tx_send_packet,
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.ccid_hc_tx_packet_sent = ccid2_hc_tx_packet_sent,
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.ccid_hc_tx_packet_recv = ccid2_hc_tx_packet_recv,
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.ccid_hc_rx_obj_size = sizeof(struct ccid2_hc_rx_sock),
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.ccid_hc_rx_packet_recv = ccid2_hc_rx_packet_recv,
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.ccid_id = DCCPC_CCID2,
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.ccid_name = "TCP-like",
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.ccid_owner = THIS_MODULE,
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.ccid_hc_tx_obj_size = sizeof(struct ccid2_hc_tx_sock),
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.ccid_hc_tx_init = ccid2_hc_tx_init,
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.ccid_hc_tx_exit = ccid2_hc_tx_exit,
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.ccid_hc_tx_send_packet = ccid2_hc_tx_send_packet,
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.ccid_hc_tx_packet_sent = ccid2_hc_tx_packet_sent,
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.ccid_hc_tx_parse_options = ccid2_hc_tx_parse_options,
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.ccid_hc_tx_packet_recv = ccid2_hc_tx_packet_recv,
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.ccid_hc_rx_obj_size = sizeof(struct ccid2_hc_rx_sock),
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.ccid_hc_rx_packet_recv = ccid2_hc_rx_packet_recv,
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};
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#ifdef CONFIG_IP_DCCP_CCID2_DEBUG
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@ -47,6 +47,7 @@ struct ccid2_seq {
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* @lastrtt: time RTT was last measured
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* @rpseq: last consecutive seqno
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* @rpdupack: dupacks since rpseq
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* @av_chunks: list of Ack Vectors received on current skb
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*/
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struct ccid2_hc_tx_sock {
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u32 cwnd;
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@ -66,6 +67,7 @@ struct ccid2_hc_tx_sock {
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int rpdupack;
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unsigned long last_cong;
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u64 high_ack;
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struct list_head av_chunks;
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};
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struct ccid2_hc_rx_sock {
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@ -128,13 +128,6 @@ int dccp_parse_options(struct sock *sk, struct dccp_request_sock *dreq,
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if (rc)
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goto out_featneg_failed;
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break;
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case DCCPO_ACK_VECTOR_0:
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case DCCPO_ACK_VECTOR_1:
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if (dccp_packet_without_ack(skb)) /* RFC 4340, 11.4 */
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break;
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dccp_pr_debug("%s Ack Vector (len=%u)\n", dccp_role(sk),
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len);
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break;
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case DCCPO_TIMESTAMP:
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if (len != 4)
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goto out_invalid_option;
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@ -224,6 +217,16 @@ int dccp_parse_options(struct sock *sk, struct dccp_request_sock *dreq,
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pkt_type, opt, value, len))
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goto out_invalid_option;
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break;
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case DCCPO_ACK_VECTOR_0:
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case DCCPO_ACK_VECTOR_1:
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if (dccp_packet_without_ack(skb)) /* RFC 4340, 11.4 */
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break;
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/*
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* Ack vectors are processed by the TX CCID if it is
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* interested. The RX CCID need not parse Ack Vectors,
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* since it is only interested in clearing old state.
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* Fall through.
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*/
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case DCCPO_MIN_TX_CCID_SPECIFIC ... DCCPO_MAX_TX_CCID_SPECIFIC:
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if (ccid_hc_tx_parse_options(dp->dccps_hc_tx_ccid, sk,
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pkt_type, opt, value, len))
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