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-rw-r--r--net/dccp/output.c709
1 files changed, 709 insertions, 0 deletions
diff --git a/net/dccp/output.c b/net/dccp/output.c
new file mode 100644
index 000000000..fd2eb148d
--- /dev/null
+++ b/net/dccp/output.c
@@ -0,0 +1,709 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * net/dccp/output.c
+ *
+ * An implementation of the DCCP protocol
+ * Arnaldo Carvalho de Melo <acme@conectiva.com.br>
+ */
+
+#include <linux/dccp.h>
+#include <linux/kernel.h>
+#include <linux/skbuff.h>
+#include <linux/slab.h>
+#include <linux/sched/signal.h>
+
+#include <net/inet_sock.h>
+#include <net/sock.h>
+
+#include "ackvec.h"
+#include "ccid.h"
+#include "dccp.h"
+
+static inline void dccp_event_ack_sent(struct sock *sk)
+{
+ inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
+}
+
+/* enqueue @skb on sk_send_head for retransmission, return clone to send now */
+static struct sk_buff *dccp_skb_entail(struct sock *sk, struct sk_buff *skb)
+{
+ skb_set_owner_w(skb, sk);
+ WARN_ON(sk->sk_send_head);
+ sk->sk_send_head = skb;
+ return skb_clone(sk->sk_send_head, gfp_any());
+}
+
+/*
+ * All SKB's seen here are completely headerless. It is our
+ * job to build the DCCP header, and pass the packet down to
+ * IP so it can do the same plus pass the packet off to the
+ * device.
+ */
+static int dccp_transmit_skb(struct sock *sk, struct sk_buff *skb)
+{
+ if (likely(skb != NULL)) {
+ struct inet_sock *inet = inet_sk(sk);
+ const struct inet_connection_sock *icsk = inet_csk(sk);
+ struct dccp_sock *dp = dccp_sk(sk);
+ struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
+ struct dccp_hdr *dh;
+ /* XXX For now we're using only 48 bits sequence numbers */
+ const u32 dccp_header_size = sizeof(*dh) +
+ sizeof(struct dccp_hdr_ext) +
+ dccp_packet_hdr_len(dcb->dccpd_type);
+ int err, set_ack = 1;
+ u64 ackno = dp->dccps_gsr;
+ /*
+ * Increment GSS here already in case the option code needs it.
+ * Update GSS for real only if option processing below succeeds.
+ */
+ dcb->dccpd_seq = ADD48(dp->dccps_gss, 1);
+
+ switch (dcb->dccpd_type) {
+ case DCCP_PKT_DATA:
+ set_ack = 0;
+ fallthrough;
+ case DCCP_PKT_DATAACK:
+ case DCCP_PKT_RESET:
+ break;
+
+ case DCCP_PKT_REQUEST:
+ set_ack = 0;
+ /* Use ISS on the first (non-retransmitted) Request. */
+ if (icsk->icsk_retransmits == 0)
+ dcb->dccpd_seq = dp->dccps_iss;
+ fallthrough;
+
+ case DCCP_PKT_SYNC:
+ case DCCP_PKT_SYNCACK:
+ ackno = dcb->dccpd_ack_seq;
+ fallthrough;
+ default:
+ /*
+ * Set owner/destructor: some skbs are allocated via
+ * alloc_skb (e.g. when retransmission may happen).
+ * Only Data, DataAck, and Reset packets should come
+ * through here with skb->sk set.
+ */
+ WARN_ON(skb->sk);
+ skb_set_owner_w(skb, sk);
+ break;
+ }
+
+ if (dccp_insert_options(sk, skb)) {
+ kfree_skb(skb);
+ return -EPROTO;
+ }
+
+
+ /* Build DCCP header and checksum it. */
+ dh = dccp_zeroed_hdr(skb, dccp_header_size);
+ dh->dccph_type = dcb->dccpd_type;
+ dh->dccph_sport = inet->inet_sport;
+ dh->dccph_dport = inet->inet_dport;
+ dh->dccph_doff = (dccp_header_size + dcb->dccpd_opt_len) / 4;
+ dh->dccph_ccval = dcb->dccpd_ccval;
+ dh->dccph_cscov = dp->dccps_pcslen;
+ /* XXX For now we're using only 48 bits sequence numbers */
+ dh->dccph_x = 1;
+
+ dccp_update_gss(sk, dcb->dccpd_seq);
+ dccp_hdr_set_seq(dh, dp->dccps_gss);
+ if (set_ack)
+ dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), ackno);
+
+ switch (dcb->dccpd_type) {
+ case DCCP_PKT_REQUEST:
+ dccp_hdr_request(skb)->dccph_req_service =
+ dp->dccps_service;
+ /*
+ * Limit Ack window to ISS <= P.ackno <= GSS, so that
+ * only Responses to Requests we sent are considered.
+ */
+ dp->dccps_awl = dp->dccps_iss;
+ break;
+ case DCCP_PKT_RESET:
+ dccp_hdr_reset(skb)->dccph_reset_code =
+ dcb->dccpd_reset_code;
+ break;
+ }
+
+ icsk->icsk_af_ops->send_check(sk, skb);
+
+ if (set_ack)
+ dccp_event_ack_sent(sk);
+
+ DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
+
+ err = icsk->icsk_af_ops->queue_xmit(sk, skb, &inet->cork.fl);
+ return net_xmit_eval(err);
+ }
+ return -ENOBUFS;
+}
+
+/**
+ * dccp_determine_ccmps - Find out about CCID-specific packet-size limits
+ * @dp: socket to find packet size limits of
+ *
+ * We only consider the HC-sender CCID for setting the CCMPS (RFC 4340, 14.),
+ * since the RX CCID is restricted to feedback packets (Acks), which are small
+ * in comparison with the data traffic. A value of 0 means "no current CCMPS".
+ */
+static u32 dccp_determine_ccmps(const struct dccp_sock *dp)
+{
+ const struct ccid *tx_ccid = dp->dccps_hc_tx_ccid;
+
+ if (tx_ccid == NULL || tx_ccid->ccid_ops == NULL)
+ return 0;
+ return tx_ccid->ccid_ops->ccid_ccmps;
+}
+
+unsigned int dccp_sync_mss(struct sock *sk, u32 pmtu)
+{
+ struct inet_connection_sock *icsk = inet_csk(sk);
+ struct dccp_sock *dp = dccp_sk(sk);
+ u32 ccmps = dccp_determine_ccmps(dp);
+ u32 cur_mps = ccmps ? min(pmtu, ccmps) : pmtu;
+
+ /* Account for header lengths and IPv4/v6 option overhead */
+ cur_mps -= (icsk->icsk_af_ops->net_header_len + icsk->icsk_ext_hdr_len +
+ sizeof(struct dccp_hdr) + sizeof(struct dccp_hdr_ext));
+
+ /*
+ * Leave enough headroom for common DCCP header options.
+ * This only considers options which may appear on DCCP-Data packets, as
+ * per table 3 in RFC 4340, 5.8. When running out of space for other
+ * options (eg. Ack Vector which can take up to 255 bytes), it is better
+ * to schedule a separate Ack. Thus we leave headroom for the following:
+ * - 1 byte for Slow Receiver (11.6)
+ * - 6 bytes for Timestamp (13.1)
+ * - 10 bytes for Timestamp Echo (13.3)
+ * - 8 bytes for NDP count (7.7, when activated)
+ * - 6 bytes for Data Checksum (9.3)
+ * - %DCCPAV_MIN_OPTLEN bytes for Ack Vector size (11.4, when enabled)
+ */
+ cur_mps -= roundup(1 + 6 + 10 + dp->dccps_send_ndp_count * 8 + 6 +
+ (dp->dccps_hc_rx_ackvec ? DCCPAV_MIN_OPTLEN : 0), 4);
+
+ /* And store cached results */
+ icsk->icsk_pmtu_cookie = pmtu;
+ WRITE_ONCE(dp->dccps_mss_cache, cur_mps);
+
+ return cur_mps;
+}
+
+EXPORT_SYMBOL_GPL(dccp_sync_mss);
+
+void dccp_write_space(struct sock *sk)
+{
+ struct socket_wq *wq;
+
+ rcu_read_lock();
+ wq = rcu_dereference(sk->sk_wq);
+ if (skwq_has_sleeper(wq))
+ wake_up_interruptible(&wq->wait);
+ /* Should agree with poll, otherwise some programs break */
+ if (sock_writeable(sk))
+ sk_wake_async(sk, SOCK_WAKE_SPACE, POLL_OUT);
+
+ rcu_read_unlock();
+}
+
+/**
+ * dccp_wait_for_ccid - Await CCID send permission
+ * @sk: socket to wait for
+ * @delay: timeout in jiffies
+ *
+ * This is used by CCIDs which need to delay the send time in process context.
+ */
+static int dccp_wait_for_ccid(struct sock *sk, unsigned long delay)
+{
+ DEFINE_WAIT(wait);
+ long remaining;
+
+ prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
+ sk->sk_write_pending++;
+ release_sock(sk);
+
+ remaining = schedule_timeout(delay);
+
+ lock_sock(sk);
+ sk->sk_write_pending--;
+ finish_wait(sk_sleep(sk), &wait);
+
+ if (signal_pending(current) || sk->sk_err)
+ return -1;
+ return remaining;
+}
+
+/**
+ * dccp_xmit_packet - Send data packet under control of CCID
+ * @sk: socket to send data packet on
+ *
+ * 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 = dccp_qpolicy_pop(sk);
+
+ 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);
+
+ /*
+ * If the CCID needs to transfer additional header options out-of-band
+ * (e.g. Ack Vectors or feature-negotiation options), it activates this
+ * flag to schedule a Sync. The Sync will automatically incorporate all
+ * currently pending header options, thus clearing the backlog.
+ */
+ if (dp->dccps_sync_scheduled)
+ dccp_send_sync(sk, dp->dccps_gsr, DCCP_PKT_SYNC);
+}
+
+/**
+ * dccp_flush_write_queue - Drain queue at end of connection
+ * @sk: socket to be drained
+ * @time_budget: time allowed to drain the queue
+ *
+ * Since dccp_sendmsg queues packets without waiting for them to be sent, it may
+ * happen that the TX queue is not empty at the end of a connection. We give the
+ * HC-sender CCID a grace period of up to @time_budget jiffies. If this function
+ * returns with a non-empty write queue, it will be purged later.
+ */
+void dccp_flush_write_queue(struct sock *sk, long *time_budget)
+{
+ struct dccp_sock *dp = dccp_sk(sk);
+ struct sk_buff *skb;
+ long delay, rc;
+
+ while (*time_budget > 0 && (skb = skb_peek(&sk->sk_write_queue))) {
+ rc = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb);
+
+ switch (ccid_packet_dequeue_eval(rc)) {
+ case CCID_PACKET_WILL_DEQUEUE_LATER:
+ /*
+ * If the CCID determines when to send, the next sending
+ * time is unknown or the CCID may not even send again
+ * (e.g. remote host crashes or lost Ack packets).
+ */
+ DCCP_WARN("CCID did not manage to send all packets\n");
+ return;
+ case CCID_PACKET_DELAY:
+ delay = msecs_to_jiffies(rc);
+ if (delay > *time_budget)
+ return;
+ rc = dccp_wait_for_ccid(sk, delay);
+ if (rc < 0)
+ return;
+ *time_budget -= (delay - rc);
+ /* check again if we can send now */
+ break;
+ case CCID_PACKET_SEND_AT_ONCE:
+ dccp_xmit_packet(sk);
+ break;
+ case CCID_PACKET_ERR:
+ skb_dequeue(&sk->sk_write_queue);
+ kfree_skb(skb);
+ dccp_pr_debug("packet discarded due to err=%ld\n", rc);
+ }
+ }
+}
+
+void dccp_write_xmit(struct sock *sk)
+{
+ struct dccp_sock *dp = dccp_sk(sk);
+ struct sk_buff *skb;
+
+ while ((skb = dccp_qpolicy_top(sk))) {
+ int rc = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb);
+
+ switch (ccid_packet_dequeue_eval(rc)) {
+ case CCID_PACKET_WILL_DEQUEUE_LATER:
+ return;
+ case CCID_PACKET_DELAY:
+ sk_reset_timer(sk, &dp->dccps_xmit_timer,
+ jiffies + msecs_to_jiffies(rc));
+ return;
+ case CCID_PACKET_SEND_AT_ONCE:
+ dccp_xmit_packet(sk);
+ break;
+ case CCID_PACKET_ERR:
+ dccp_qpolicy_drop(sk, skb);
+ dccp_pr_debug("packet discarded due to err=%d\n", rc);
+ }
+ }
+}
+
+/**
+ * dccp_retransmit_skb - Retransmit Request, Close, or CloseReq packets
+ * @sk: socket to perform retransmit on
+ *
+ * There are only four retransmittable packet types in DCCP:
+ * - Request in client-REQUEST state (sec. 8.1.1),
+ * - CloseReq in server-CLOSEREQ state (sec. 8.3),
+ * - Close in node-CLOSING state (sec. 8.3),
+ * - Acks in client-PARTOPEN state (sec. 8.1.5, handled by dccp_delack_timer()).
+ * This function expects sk->sk_send_head to contain the original skb.
+ */
+int dccp_retransmit_skb(struct sock *sk)
+{
+ WARN_ON(sk->sk_send_head == NULL);
+
+ if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk) != 0)
+ return -EHOSTUNREACH; /* Routing failure or similar. */
+
+ /* this count is used to distinguish original and retransmitted skb */
+ inet_csk(sk)->icsk_retransmits++;
+
+ return dccp_transmit_skb(sk, skb_clone(sk->sk_send_head, GFP_ATOMIC));
+}
+
+struct sk_buff *dccp_make_response(const struct sock *sk, struct dst_entry *dst,
+ struct request_sock *req)
+{
+ struct dccp_hdr *dh;
+ struct dccp_request_sock *dreq;
+ const u32 dccp_header_size = sizeof(struct dccp_hdr) +
+ sizeof(struct dccp_hdr_ext) +
+ sizeof(struct dccp_hdr_response);
+ struct sk_buff *skb;
+
+ /* sk is marked const to clearly express we dont hold socket lock.
+ * sock_wmalloc() will atomically change sk->sk_wmem_alloc,
+ * it is safe to promote sk to non const.
+ */
+ skb = sock_wmalloc((struct sock *)sk, MAX_DCCP_HEADER, 1,
+ GFP_ATOMIC);
+ if (!skb)
+ return NULL;
+
+ skb_reserve(skb, MAX_DCCP_HEADER);
+
+ skb_dst_set(skb, dst_clone(dst));
+
+ dreq = dccp_rsk(req);
+ if (inet_rsk(req)->acked) /* increase GSS upon retransmission */
+ dccp_inc_seqno(&dreq->dreq_gss);
+ DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_RESPONSE;
+ DCCP_SKB_CB(skb)->dccpd_seq = dreq->dreq_gss;
+
+ /* Resolve feature dependencies resulting from choice of CCID */
+ if (dccp_feat_server_ccid_dependencies(dreq))
+ goto response_failed;
+
+ if (dccp_insert_options_rsk(dreq, skb))
+ goto response_failed;
+
+ /* Build and checksum header */
+ dh = dccp_zeroed_hdr(skb, dccp_header_size);
+
+ dh->dccph_sport = htons(inet_rsk(req)->ir_num);
+ dh->dccph_dport = inet_rsk(req)->ir_rmt_port;
+ dh->dccph_doff = (dccp_header_size +
+ DCCP_SKB_CB(skb)->dccpd_opt_len) / 4;
+ dh->dccph_type = DCCP_PKT_RESPONSE;
+ dh->dccph_x = 1;
+ dccp_hdr_set_seq(dh, dreq->dreq_gss);
+ dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), dreq->dreq_gsr);
+ dccp_hdr_response(skb)->dccph_resp_service = dreq->dreq_service;
+
+ dccp_csum_outgoing(skb);
+
+ /* We use `acked' to remember that a Response was already sent. */
+ inet_rsk(req)->acked = 1;
+ DCCP_INC_STATS(DCCP_MIB_OUTSEGS);
+ return skb;
+response_failed:
+ kfree_skb(skb);
+ return NULL;
+}
+
+EXPORT_SYMBOL_GPL(dccp_make_response);
+
+/* answer offending packet in @rcv_skb with Reset from control socket @ctl */
+struct sk_buff *dccp_ctl_make_reset(struct sock *sk, struct sk_buff *rcv_skb)
+{
+ struct dccp_hdr *rxdh = dccp_hdr(rcv_skb), *dh;
+ struct dccp_skb_cb *dcb = DCCP_SKB_CB(rcv_skb);
+ const u32 dccp_hdr_reset_len = sizeof(struct dccp_hdr) +
+ sizeof(struct dccp_hdr_ext) +
+ sizeof(struct dccp_hdr_reset);
+ struct dccp_hdr_reset *dhr;
+ struct sk_buff *skb;
+
+ skb = alloc_skb(sk->sk_prot->max_header, GFP_ATOMIC);
+ if (skb == NULL)
+ return NULL;
+
+ skb_reserve(skb, sk->sk_prot->max_header);
+
+ /* Swap the send and the receive. */
+ dh = dccp_zeroed_hdr(skb, dccp_hdr_reset_len);
+ dh->dccph_type = DCCP_PKT_RESET;
+ dh->dccph_sport = rxdh->dccph_dport;
+ dh->dccph_dport = rxdh->dccph_sport;
+ dh->dccph_doff = dccp_hdr_reset_len / 4;
+ dh->dccph_x = 1;
+
+ dhr = dccp_hdr_reset(skb);
+ dhr->dccph_reset_code = dcb->dccpd_reset_code;
+
+ switch (dcb->dccpd_reset_code) {
+ case DCCP_RESET_CODE_PACKET_ERROR:
+ dhr->dccph_reset_data[0] = rxdh->dccph_type;
+ break;
+ case DCCP_RESET_CODE_OPTION_ERROR:
+ case DCCP_RESET_CODE_MANDATORY_ERROR:
+ memcpy(dhr->dccph_reset_data, dcb->dccpd_reset_data, 3);
+ break;
+ }
+ /*
+ * From RFC 4340, 8.3.1:
+ * If P.ackno exists, set R.seqno := P.ackno + 1.
+ * Else set R.seqno := 0.
+ */
+ if (dcb->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
+ dccp_hdr_set_seq(dh, ADD48(dcb->dccpd_ack_seq, 1));
+ dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), dcb->dccpd_seq);
+
+ dccp_csum_outgoing(skb);
+ return skb;
+}
+
+EXPORT_SYMBOL_GPL(dccp_ctl_make_reset);
+
+/* send Reset on established socket, to close or abort the connection */
+int dccp_send_reset(struct sock *sk, enum dccp_reset_codes code)
+{
+ struct sk_buff *skb;
+ /*
+ * FIXME: what if rebuild_header fails?
+ * Should we be doing a rebuild_header here?
+ */
+ int err = inet_csk(sk)->icsk_af_ops->rebuild_header(sk);
+
+ if (err != 0)
+ return err;
+
+ skb = sock_wmalloc(sk, sk->sk_prot->max_header, 1, GFP_ATOMIC);
+ if (skb == NULL)
+ return -ENOBUFS;
+
+ /* Reserve space for headers and prepare control bits. */
+ skb_reserve(skb, sk->sk_prot->max_header);
+ DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_RESET;
+ DCCP_SKB_CB(skb)->dccpd_reset_code = code;
+
+ return dccp_transmit_skb(sk, skb);
+}
+
+/*
+ * Do all connect socket setups that can be done AF independent.
+ */
+int dccp_connect(struct sock *sk)
+{
+ struct sk_buff *skb;
+ struct dccp_sock *dp = dccp_sk(sk);
+ struct dst_entry *dst = __sk_dst_get(sk);
+ struct inet_connection_sock *icsk = inet_csk(sk);
+
+ sk->sk_err = 0;
+ sock_reset_flag(sk, SOCK_DONE);
+
+ dccp_sync_mss(sk, dst_mtu(dst));
+
+ /* do not connect if feature negotiation setup fails */
+ if (dccp_feat_finalise_settings(dccp_sk(sk)))
+ return -EPROTO;
+
+ /* Initialise GAR as per 8.5; AWL/AWH are set in dccp_transmit_skb() */
+ dp->dccps_gar = dp->dccps_iss;
+
+ skb = alloc_skb(sk->sk_prot->max_header, sk->sk_allocation);
+ if (unlikely(skb == NULL))
+ return -ENOBUFS;
+
+ /* Reserve space for headers. */
+ skb_reserve(skb, sk->sk_prot->max_header);
+
+ DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_REQUEST;
+
+ dccp_transmit_skb(sk, dccp_skb_entail(sk, skb));
+ DCCP_INC_STATS(DCCP_MIB_ACTIVEOPENS);
+
+ /* Timer for repeating the REQUEST until an answer. */
+ icsk->icsk_retransmits = 0;
+ inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
+ icsk->icsk_rto, DCCP_RTO_MAX);
+ return 0;
+}
+
+EXPORT_SYMBOL_GPL(dccp_connect);
+
+void dccp_send_ack(struct sock *sk)
+{
+ /* If we have been reset, we may not send again. */
+ if (sk->sk_state != DCCP_CLOSED) {
+ struct sk_buff *skb = alloc_skb(sk->sk_prot->max_header,
+ GFP_ATOMIC);
+
+ if (skb == NULL) {
+ inet_csk_schedule_ack(sk);
+ inet_csk(sk)->icsk_ack.ato = TCP_ATO_MIN;
+ inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
+ TCP_DELACK_MAX,
+ DCCP_RTO_MAX);
+ return;
+ }
+
+ /* Reserve space for headers */
+ skb_reserve(skb, sk->sk_prot->max_header);
+ DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_ACK;
+ dccp_transmit_skb(sk, skb);
+ }
+}
+
+EXPORT_SYMBOL_GPL(dccp_send_ack);
+
+#if 0
+/* FIXME: Is this still necessary (11.3) - currently nowhere used by DCCP. */
+void dccp_send_delayed_ack(struct sock *sk)
+{
+ struct inet_connection_sock *icsk = inet_csk(sk);
+ /*
+ * FIXME: tune this timer. elapsed time fixes the skew, so no problem
+ * with using 2s, and active senders also piggyback the ACK into a
+ * DATAACK packet, so this is really for quiescent senders.
+ */
+ unsigned long timeout = jiffies + 2 * HZ;
+
+ /* Use new timeout only if there wasn't a older one earlier. */
+ if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) {
+ /* If delack timer was blocked or is about to expire,
+ * send ACK now.
+ *
+ * FIXME: check the "about to expire" part
+ */
+ if (icsk->icsk_ack.blocked) {
+ dccp_send_ack(sk);
+ return;
+ }
+
+ if (!time_before(timeout, icsk->icsk_ack.timeout))
+ timeout = icsk->icsk_ack.timeout;
+ }
+ icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER;
+ icsk->icsk_ack.timeout = timeout;
+ sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout);
+}
+#endif
+
+void dccp_send_sync(struct sock *sk, const u64 ackno,
+ const enum dccp_pkt_type pkt_type)
+{
+ /*
+ * We are not putting this on the write queue, so
+ * dccp_transmit_skb() will set the ownership to this
+ * sock.
+ */
+ struct sk_buff *skb = alloc_skb(sk->sk_prot->max_header, GFP_ATOMIC);
+
+ if (skb == NULL) {
+ /* FIXME: how to make sure the sync is sent? */
+ DCCP_CRIT("could not send %s", dccp_packet_name(pkt_type));
+ return;
+ }
+
+ /* Reserve space for headers and prepare control bits. */
+ skb_reserve(skb, sk->sk_prot->max_header);
+ DCCP_SKB_CB(skb)->dccpd_type = pkt_type;
+ DCCP_SKB_CB(skb)->dccpd_ack_seq = ackno;
+
+ /*
+ * Clear the flag in case the Sync was scheduled for out-of-band data,
+ * such as carrying a long Ack Vector.
+ */
+ dccp_sk(sk)->dccps_sync_scheduled = 0;
+
+ dccp_transmit_skb(sk, skb);
+}
+
+EXPORT_SYMBOL_GPL(dccp_send_sync);
+
+/*
+ * Send a DCCP_PKT_CLOSE/CLOSEREQ. The caller locks the socket for us. This
+ * cannot be allowed to fail queueing a DCCP_PKT_CLOSE/CLOSEREQ frame under
+ * any circumstances.
+ */
+void dccp_send_close(struct sock *sk, const int active)
+{
+ struct dccp_sock *dp = dccp_sk(sk);
+ struct sk_buff *skb;
+ const gfp_t prio = active ? GFP_KERNEL : GFP_ATOMIC;
+
+ skb = alloc_skb(sk->sk_prot->max_header, prio);
+ if (skb == NULL)
+ return;
+
+ /* Reserve space for headers and prepare control bits. */
+ skb_reserve(skb, sk->sk_prot->max_header);
+ if (dp->dccps_role == DCCP_ROLE_SERVER && !dp->dccps_server_timewait)
+ DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_CLOSEREQ;
+ else
+ DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_CLOSE;
+
+ if (active) {
+ skb = dccp_skb_entail(sk, skb);
+ /*
+ * Retransmission timer for active-close: RFC 4340, 8.3 requires
+ * to retransmit the Close/CloseReq until the CLOSING/CLOSEREQ
+ * state can be left. The initial timeout is 2 RTTs.
+ * Since RTT measurement is done by the CCIDs, there is no easy
+ * way to get an RTT sample. The fallback RTT from RFC 4340, 3.4
+ * is too low (200ms); we use a high value to avoid unnecessary
+ * retransmissions when the link RTT is > 0.2 seconds.
+ * FIXME: Let main module sample RTTs and use that instead.
+ */
+ inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
+ DCCP_TIMEOUT_INIT, DCCP_RTO_MAX);
+ }
+ dccp_transmit_skb(sk, skb);
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-20 16:08:47 +0000