+/**
+ * dccp_xmit_packet - Send data packet under control of CCID
+ * Transmits next-queued payload and informs CCID to account for the packet.
+ */
+static void dccp_xmit_packet(struct sock *sk)
+{
+ int err, len;
+ struct dccp_sock *dp = dccp_sk(sk);
+ struct sk_buff *skb = skb_dequeue(&sk->sk_write_queue);
+
+ if (unlikely(skb == NULL))
+ return;
+ len = skb->len;
+
+ if (sk->sk_state == DCCP_PARTOPEN) {
+ const u32 cur_mps = dp->dccps_mss_cache - DCCP_FEATNEG_OVERHEAD;
+ /*
+ * See 8.1.5 - Handshake Completion.
+ *
+ * For robustness we resend Confirm options until the client has
+ * entered OPEN. During the initial feature negotiation, the MPS
+ * is smaller than usual, reduced by the Change/Confirm options.
+ */
+ if (!list_empty(&dp->dccps_featneg) && len > cur_mps) {
+ DCCP_WARN("Payload too large (%d) for featneg.\n", len);
+ dccp_send_ack(sk);
+ dccp_feat_list_purge(&dp->dccps_featneg);
+ }
+
+ inet_csk_schedule_ack(sk);
+ inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
+ inet_csk(sk)->icsk_rto,
+ DCCP_RTO_MAX);
+ DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_DATAACK;
+ } else if (dccp_ack_pending(sk)) {
+ DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_DATAACK;
+ } else {
+ DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_DATA;
+ }
+
+ err = dccp_transmit_skb(sk, skb);
+ if (err)
+ dccp_pr_debug("transmit_skb() returned err=%d\n", err);
+ /*
+ * Register this one as sent even if an error occurred. To the remote
+ * end a local packet drop is indistinguishable from network loss, i.e.
+ * any local drop will eventually be reported via receiver feedback.
+ */
+ ccid_hc_tx_packet_sent(dp->dccps_hc_tx_ccid, sk, len);
+}
+