446 lines
12 KiB
C
446 lines
12 KiB
C
/*
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* net/dccp/output.c
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*
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* An implementation of the DCCP protocol
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* Arnaldo Carvalho de Melo <acme@conectiva.com.br>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/config.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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#include "ccid.h"
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#include "dccp.h"
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static inline void dccp_event_ack_sent(struct sock *sk)
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{
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inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
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}
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/*
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* All SKB's seen here are completely headerless. It is our
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* job to build the DCCP header, and pass the packet down to
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* IP so it can do the same plus pass the packet off to the
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* device.
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*/
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int dccp_transmit_skb(struct sock *sk, struct sk_buff *skb)
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{
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if (likely(skb != NULL)) {
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const struct inet_sock *inet = inet_sk(sk);
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struct dccp_sock *dp = dccp_sk(sk);
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struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
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struct dccp_hdr *dh;
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/* XXX For now we're using only 48 bits sequence numbers */
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const int dccp_header_size = sizeof(*dh) +
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sizeof(struct dccp_hdr_ext) +
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dccp_packet_hdr_len(dcb->dccpd_type);
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int err, set_ack = 1;
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u64 ackno = dp->dccps_gsr;
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/*
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* FIXME: study DCCP_PKT_SYNC[ACK] to see what is the right thing
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* to do here...
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*/
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dccp_inc_seqno(&dp->dccps_gss);
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dcb->dccpd_seq = dp->dccps_gss;
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dccp_insert_options(sk, skb);
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switch (dcb->dccpd_type) {
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case DCCP_PKT_DATA:
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set_ack = 0;
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break;
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case DCCP_PKT_SYNC:
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case DCCP_PKT_SYNCACK:
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ackno = dcb->dccpd_seq;
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break;
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}
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skb->h.raw = skb_push(skb, dccp_header_size);
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dh = dccp_hdr(skb);
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/* Data packets are not cloned as they are never retransmitted */
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if (skb_cloned(skb))
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skb_set_owner_w(skb, sk);
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/* Build DCCP header and checksum it. */
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memset(dh, 0, dccp_header_size);
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dh->dccph_type = dcb->dccpd_type;
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dh->dccph_sport = inet->sport;
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dh->dccph_dport = inet->dport;
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dh->dccph_doff = (dccp_header_size + dcb->dccpd_opt_len) / 4;
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dh->dccph_ccval = dcb->dccpd_ccval;
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/* XXX For now we're using only 48 bits sequence numbers */
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dh->dccph_x = 1;
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dp->dccps_awh = dp->dccps_gss;
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dccp_hdr_set_seq(dh, dp->dccps_gss);
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if (set_ack)
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dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), ackno);
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switch (dcb->dccpd_type) {
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case DCCP_PKT_REQUEST:
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dccp_hdr_request(skb)->dccph_req_service = dcb->dccpd_service;
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break;
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case DCCP_PKT_RESET:
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dccp_hdr_reset(skb)->dccph_reset_code = dcb->dccpd_reset_code;
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break;
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}
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dh->dccph_checksum = dccp_v4_checksum(skb, inet->saddr,
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inet->daddr);
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if (dcb->dccpd_type == DCCP_PKT_ACK ||
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dcb->dccpd_type == DCCP_PKT_DATAACK)
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dccp_event_ack_sent(sk);
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DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
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err = ip_queue_xmit(skb, 0);
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if (err <= 0)
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return err;
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/* NET_XMIT_CN is special. It does not guarantee,
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* that this packet is lost. It tells that device
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* is about to start to drop packets or already
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* drops some packets of the same priority and
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* invokes us to send less aggressively.
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*/
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return err == NET_XMIT_CN ? 0 : err;
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}
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return -ENOBUFS;
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}
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unsigned int dccp_sync_mss(struct sock *sk, u32 pmtu)
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{
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struct dccp_sock *dp = dccp_sk(sk);
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int mss_now;
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/*
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* FIXME: we really should be using the af_specific thing to support IPv6.
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* mss_now = pmtu - tp->af_specific->net_header_len - sizeof(struct dccp_hdr) - sizeof(struct dccp_hdr_ext);
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*/
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mss_now = pmtu - sizeof(struct iphdr) - sizeof(struct dccp_hdr) - sizeof(struct dccp_hdr_ext);
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/* Now subtract optional transport overhead */
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mss_now -= dp->dccps_ext_header_len;
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/*
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* FIXME: this should come from the CCID infrastructure, where, say,
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* TFRC will say it wants TIMESTAMPS, ELAPSED time, etc, for now lets
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* put a rough estimate for NDP + TIMESTAMP + TIMESTAMP_ECHO + ELAPSED
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* TIME + TFRC_OPT_LOSS_EVENT_RATE + TFRC_OPT_RECEIVE_RATE + padding to
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* make it a multiple of 4
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*/
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mss_now -= ((5 + 6 + 10 + 6 + 6 + 6 + 3) / 4) * 4;
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/* And store cached results */
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dp->dccps_pmtu_cookie = pmtu;
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dp->dccps_mss_cache = mss_now;
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return mss_now;
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}
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int dccp_write_xmit(struct sock *sk, struct sk_buff *skb, const int len)
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{
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const struct dccp_sock *dp = dccp_sk(sk);
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int err = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb, len);
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if (err == 0) {
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const struct dccp_ackpkts *ap = dp->dccps_hc_rx_ackpkts;
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struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
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if (sk->sk_state == DCCP_PARTOPEN) {
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/* See 8.1.5. Handshake Completion */
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inet_csk_schedule_ack(sk);
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inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
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inet_csk(sk)->icsk_rto,
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DCCP_RTO_MAX);
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dcb->dccpd_type = DCCP_PKT_DATAACK;
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/*
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* FIXME: we really should have a
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* dccps_ack_pending or use icsk.
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*/
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} else if (inet_csk_ack_scheduled(sk) ||
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(dp->dccps_options.dccpo_send_ack_vector &&
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ap->dccpap_buf_ackno != DCCP_MAX_SEQNO + 1 &&
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ap->dccpap_ack_seqno == DCCP_MAX_SEQNO + 1))
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dcb->dccpd_type = DCCP_PKT_DATAACK;
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else
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dcb->dccpd_type = DCCP_PKT_DATA;
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err = dccp_transmit_skb(sk, skb);
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ccid_hc_tx_packet_sent(dp->dccps_hc_tx_ccid, sk, 0, len);
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}
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return err;
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}
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int dccp_retransmit_skb(struct sock *sk, struct sk_buff *skb)
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{
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if (inet_sk_rebuild_header(sk) != 0)
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return -EHOSTUNREACH; /* Routing failure or similar. */
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return dccp_transmit_skb(sk, (skb_cloned(skb) ?
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pskb_copy(skb, GFP_ATOMIC):
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skb_clone(skb, GFP_ATOMIC)));
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}
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struct sk_buff *dccp_make_response(struct sock *sk, struct dst_entry *dst,
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struct request_sock *req)
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{
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struct dccp_hdr *dh;
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const int dccp_header_size = sizeof(struct dccp_hdr) +
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sizeof(struct dccp_hdr_ext) +
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sizeof(struct dccp_hdr_response);
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struct sk_buff *skb = sock_wmalloc(sk, MAX_HEADER + DCCP_MAX_OPT_LEN +
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dccp_header_size, 1,
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GFP_ATOMIC);
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if (skb == NULL)
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return NULL;
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/* Reserve space for headers. */
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skb_reserve(skb, MAX_HEADER + DCCP_MAX_OPT_LEN + dccp_header_size);
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skb->dst = dst_clone(dst);
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skb->csum = 0;
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DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_RESPONSE;
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DCCP_SKB_CB(skb)->dccpd_seq = dccp_rsk(req)->dreq_iss;
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dccp_insert_options(sk, skb);
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skb->h.raw = skb_push(skb, dccp_header_size);
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dh = dccp_hdr(skb);
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memset(dh, 0, dccp_header_size);
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dh->dccph_sport = inet_sk(sk)->sport;
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dh->dccph_dport = inet_rsk(req)->rmt_port;
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dh->dccph_doff = (dccp_header_size + DCCP_SKB_CB(skb)->dccpd_opt_len) / 4;
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dh->dccph_type = DCCP_PKT_RESPONSE;
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dh->dccph_x = 1;
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dccp_hdr_set_seq(dh, dccp_rsk(req)->dreq_iss);
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dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), dccp_rsk(req)->dreq_isr);
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dh->dccph_checksum = dccp_v4_checksum(skb, inet_rsk(req)->loc_addr,
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inet_rsk(req)->rmt_addr);
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DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
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return skb;
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}
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struct sk_buff *dccp_make_reset(struct sock *sk, struct dst_entry *dst,
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const enum dccp_reset_codes code)
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{
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struct dccp_hdr *dh;
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struct dccp_sock *dp = dccp_sk(sk);
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const int dccp_header_size = sizeof(struct dccp_hdr) +
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sizeof(struct dccp_hdr_ext) +
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sizeof(struct dccp_hdr_reset);
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struct sk_buff *skb = sock_wmalloc(sk, MAX_HEADER + DCCP_MAX_OPT_LEN +
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dccp_header_size, 1,
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GFP_ATOMIC);
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if (skb == NULL)
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return NULL;
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/* Reserve space for headers. */
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skb_reserve(skb, MAX_HEADER + DCCP_MAX_OPT_LEN + dccp_header_size);
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skb->dst = dst_clone(dst);
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skb->csum = 0;
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dccp_inc_seqno(&dp->dccps_gss);
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DCCP_SKB_CB(skb)->dccpd_reset_code = code;
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DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_RESET;
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DCCP_SKB_CB(skb)->dccpd_seq = dp->dccps_gss;
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dccp_insert_options(sk, skb);
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skb->h.raw = skb_push(skb, dccp_header_size);
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dh = dccp_hdr(skb);
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memset(dh, 0, dccp_header_size);
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dh->dccph_sport = inet_sk(sk)->sport;
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dh->dccph_dport = inet_sk(sk)->dport;
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dh->dccph_doff = (dccp_header_size + DCCP_SKB_CB(skb)->dccpd_opt_len) / 4;
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dh->dccph_type = DCCP_PKT_RESET;
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dh->dccph_x = 1;
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dccp_hdr_set_seq(dh, dp->dccps_gss);
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dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), dp->dccps_gsr);
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dccp_hdr_reset(skb)->dccph_reset_code = code;
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dh->dccph_checksum = dccp_v4_checksum(skb, inet_sk(sk)->saddr,
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inet_sk(sk)->daddr);
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DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
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return skb;
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}
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/*
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* Do all connect socket setups that can be done AF independent.
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*/
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static inline void dccp_connect_init(struct sock *sk)
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{
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struct dst_entry *dst = __sk_dst_get(sk);
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struct inet_connection_sock *icsk = inet_csk(sk);
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sk->sk_err = 0;
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sock_reset_flag(sk, SOCK_DONE);
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dccp_sync_mss(sk, dst_mtu(dst));
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/*
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* FIXME: set dp->{dccps_swh,dccps_swl}, with
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* something like dccp_inc_seq
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*/
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icsk->icsk_retransmits = 0;
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}
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int dccp_connect(struct sock *sk)
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{
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struct sk_buff *skb;
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struct inet_connection_sock *icsk = inet_csk(sk);
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dccp_connect_init(sk);
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skb = alloc_skb(MAX_DCCP_HEADER + 15, sk->sk_allocation);
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if (unlikely(skb == NULL))
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return -ENOBUFS;
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/* Reserve space for headers. */
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skb_reserve(skb, MAX_DCCP_HEADER);
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DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_REQUEST;
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/* FIXME: set service to something meaningful, coming
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* from userspace*/
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DCCP_SKB_CB(skb)->dccpd_service = 0;
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skb->csum = 0;
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skb_set_owner_w(skb, sk);
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BUG_TRAP(sk->sk_send_head == NULL);
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sk->sk_send_head = skb;
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dccp_transmit_skb(sk, skb_clone(skb, GFP_KERNEL));
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DCCP_INC_STATS(DCCP_MIB_ACTIVEOPENS);
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/* Timer for repeating the REQUEST until an answer. */
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inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
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icsk->icsk_rto, DCCP_RTO_MAX);
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return 0;
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}
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void dccp_send_ack(struct sock *sk)
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{
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/* If we have been reset, we may not send again. */
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if (sk->sk_state != DCCP_CLOSED) {
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struct sk_buff *skb = alloc_skb(MAX_DCCP_HEADER, GFP_ATOMIC);
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if (skb == NULL) {
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inet_csk_schedule_ack(sk);
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inet_csk(sk)->icsk_ack.ato = TCP_ATO_MIN;
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inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, TCP_DELACK_MAX, TCP_RTO_MAX);
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return;
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}
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/* Reserve space for headers */
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skb_reserve(skb, MAX_DCCP_HEADER);
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skb->csum = 0;
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DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_ACK;
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skb_set_owner_w(skb, sk);
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dccp_transmit_skb(sk, skb);
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}
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}
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EXPORT_SYMBOL_GPL(dccp_send_ack);
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void dccp_send_delayed_ack(struct sock *sk)
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{
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struct inet_connection_sock *icsk = inet_csk(sk);
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/*
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* FIXME: tune this timer. elapsed time fixes the skew, so no problem
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* with using 2s, and active senders also piggyback the ACK into a
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* DATAACK packet, so this is really for quiescent senders.
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*/
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unsigned long timeout = jiffies + 2 * HZ;
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/* Use new timeout only if there wasn't a older one earlier. */
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if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) {
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/* If delack timer was blocked or is about to expire,
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* send ACK now.
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*
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* FIXME: check the "about to expire" part
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*/
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if (icsk->icsk_ack.blocked) {
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dccp_send_ack(sk);
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return;
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}
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if (!time_before(timeout, icsk->icsk_ack.timeout))
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timeout = icsk->icsk_ack.timeout;
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}
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icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER;
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icsk->icsk_ack.timeout = timeout;
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sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout);
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}
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void dccp_send_sync(struct sock *sk, u64 seq)
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{
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/*
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* We are not putting this on the write queue, so
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* dccp_transmit_skb() will set the ownership to this
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* sock.
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*/
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struct sk_buff *skb = alloc_skb(MAX_DCCP_HEADER, GFP_ATOMIC);
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if (skb == NULL)
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/* FIXME: how to make sure the sync is sent? */
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return;
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/* Reserve space for headers and prepare control bits. */
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skb_reserve(skb, MAX_DCCP_HEADER);
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skb->csum = 0;
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DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_SYNC;
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DCCP_SKB_CB(skb)->dccpd_seq = seq;
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skb_set_owner_w(skb, sk);
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dccp_transmit_skb(sk, skb);
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}
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/* Send a DCCP_PKT_CLOSE/CLOSEREQ. The caller locks the socket for us. This cannot be
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* allowed to fail queueing a DCCP_PKT_CLOSE/CLOSEREQ frame under any circumstances.
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*/
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void dccp_send_close(struct sock *sk)
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{
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struct dccp_sock *dp = dccp_sk(sk);
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struct sk_buff *skb;
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/* Socket is locked, keep trying until memory is available. */
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for (;;) {
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skb = alloc_skb(sk->sk_prot->max_header, GFP_KERNEL);
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if (skb != NULL)
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break;
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yield();
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}
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/* Reserve space for headers and prepare control bits. */
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skb_reserve(skb, sk->sk_prot->max_header);
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skb->csum = 0;
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DCCP_SKB_CB(skb)->dccpd_type = dp->dccps_role == DCCP_ROLE_CLIENT ? DCCP_PKT_CLOSE : DCCP_PKT_CLOSEREQ;
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skb_set_owner_w(skb, sk);
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dccp_transmit_skb(sk, skb);
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ccid_hc_rx_exit(dp->dccps_hc_rx_ccid, sk);
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ccid_hc_tx_exit(dp->dccps_hc_tx_ccid, sk);
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}
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