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-rw-r--r--net/dccp/input.c742
1 files changed, 742 insertions, 0 deletions
diff --git a/net/dccp/input.c b/net/dccp/input.c
new file mode 100644
index 000000000..85d6c8793
--- /dev/null
+++ b/net/dccp/input.c
@@ -0,0 +1,742 @@
+/*
+ * net/dccp/input.c
+ *
+ * An implementation of the DCCP protocol
+ * Arnaldo Carvalho de Melo <acme@conectiva.com.br>
+ *
+ * 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; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/dccp.h>
+#include <linux/skbuff.h>
+#include <linux/slab.h>
+
+#include <net/sock.h>
+
+#include "ackvec.h"
+#include "ccid.h"
+#include "dccp.h"
+
+/* rate-limit for syncs in reply to sequence-invalid packets; RFC 4340, 7.5.4 */
+int sysctl_dccp_sync_ratelimit __read_mostly = HZ / 8;
+
+static void dccp_enqueue_skb(struct sock *sk, struct sk_buff *skb)
+{
+ __skb_pull(skb, dccp_hdr(skb)->dccph_doff * 4);
+ __skb_queue_tail(&sk->sk_receive_queue, skb);
+ skb_set_owner_r(skb, sk);
+ sk->sk_data_ready(sk);
+}
+
+static void dccp_fin(struct sock *sk, struct sk_buff *skb)
+{
+ /*
+ * On receiving Close/CloseReq, both RD/WR shutdown are performed.
+ * RFC 4340, 8.3 says that we MAY send further Data/DataAcks after
+ * receiving the closing segment, but there is no guarantee that such
+ * data will be processed at all.
+ */
+ sk->sk_shutdown = SHUTDOWN_MASK;
+ sock_set_flag(sk, SOCK_DONE);
+ dccp_enqueue_skb(sk, skb);
+}
+
+static int dccp_rcv_close(struct sock *sk, struct sk_buff *skb)
+{
+ int queued = 0;
+
+ switch (sk->sk_state) {
+ /*
+ * We ignore Close when received in one of the following states:
+ * - CLOSED (may be a late or duplicate packet)
+ * - PASSIVE_CLOSEREQ (the peer has sent a CloseReq earlier)
+ * - RESPOND (already handled by dccp_check_req)
+ */
+ case DCCP_CLOSING:
+ /*
+ * Simultaneous-close: receiving a Close after sending one. This
+ * can happen if both client and server perform active-close and
+ * will result in an endless ping-pong of crossing and retrans-
+ * mitted Close packets, which only terminates when one of the
+ * nodes times out (min. 64 seconds). Quicker convergence can be
+ * achieved when one of the nodes acts as tie-breaker.
+ * This is ok as both ends are done with data transfer and each
+ * end is just waiting for the other to acknowledge termination.
+ */
+ if (dccp_sk(sk)->dccps_role != DCCP_ROLE_CLIENT)
+ break;
+ /* fall through */
+ case DCCP_REQUESTING:
+ case DCCP_ACTIVE_CLOSEREQ:
+ dccp_send_reset(sk, DCCP_RESET_CODE_CLOSED);
+ dccp_done(sk);
+ break;
+ case DCCP_OPEN:
+ case DCCP_PARTOPEN:
+ /* Give waiting application a chance to read pending data */
+ queued = 1;
+ dccp_fin(sk, skb);
+ dccp_set_state(sk, DCCP_PASSIVE_CLOSE);
+ /* fall through */
+ case DCCP_PASSIVE_CLOSE:
+ /*
+ * Retransmitted Close: we have already enqueued the first one.
+ */
+ sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_HUP);
+ }
+ return queued;
+}
+
+static int dccp_rcv_closereq(struct sock *sk, struct sk_buff *skb)
+{
+ int queued = 0;
+
+ /*
+ * Step 7: Check for unexpected packet types
+ * If (S.is_server and P.type == CloseReq)
+ * Send Sync packet acknowledging P.seqno
+ * Drop packet and return
+ */
+ if (dccp_sk(sk)->dccps_role != DCCP_ROLE_CLIENT) {
+ dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq, DCCP_PKT_SYNC);
+ return queued;
+ }
+
+ /* Step 13: process relevant Client states < CLOSEREQ */
+ switch (sk->sk_state) {
+ case DCCP_REQUESTING:
+ dccp_send_close(sk, 0);
+ dccp_set_state(sk, DCCP_CLOSING);
+ break;
+ case DCCP_OPEN:
+ case DCCP_PARTOPEN:
+ /* Give waiting application a chance to read pending data */
+ queued = 1;
+ dccp_fin(sk, skb);
+ dccp_set_state(sk, DCCP_PASSIVE_CLOSEREQ);
+ /* fall through */
+ case DCCP_PASSIVE_CLOSEREQ:
+ sk_wake_async(sk, SOCK_WAKE_WAITD, POLL_HUP);
+ }
+ return queued;
+}
+
+static u16 dccp_reset_code_convert(const u8 code)
+{
+ static const u16 error_code[] = {
+ [DCCP_RESET_CODE_CLOSED] = 0, /* normal termination */
+ [DCCP_RESET_CODE_UNSPECIFIED] = 0, /* nothing known */
+ [DCCP_RESET_CODE_ABORTED] = ECONNRESET,
+
+ [DCCP_RESET_CODE_NO_CONNECTION] = ECONNREFUSED,
+ [DCCP_RESET_CODE_CONNECTION_REFUSED] = ECONNREFUSED,
+ [DCCP_RESET_CODE_TOO_BUSY] = EUSERS,
+ [DCCP_RESET_CODE_AGGRESSION_PENALTY] = EDQUOT,
+
+ [DCCP_RESET_CODE_PACKET_ERROR] = ENOMSG,
+ [DCCP_RESET_CODE_BAD_INIT_COOKIE] = EBADR,
+ [DCCP_RESET_CODE_BAD_SERVICE_CODE] = EBADRQC,
+ [DCCP_RESET_CODE_OPTION_ERROR] = EILSEQ,
+ [DCCP_RESET_CODE_MANDATORY_ERROR] = EOPNOTSUPP,
+ };
+
+ return code >= DCCP_MAX_RESET_CODES ? 0 : error_code[code];
+}
+
+static void dccp_rcv_reset(struct sock *sk, struct sk_buff *skb)
+{
+ u16 err = dccp_reset_code_convert(dccp_hdr_reset(skb)->dccph_reset_code);
+
+ sk->sk_err = err;
+
+ /* Queue the equivalent of TCP fin so that dccp_recvmsg exits the loop */
+ dccp_fin(sk, skb);
+
+ if (err && !sock_flag(sk, SOCK_DEAD))
+ sk_wake_async(sk, SOCK_WAKE_IO, POLL_ERR);
+ dccp_time_wait(sk, DCCP_TIME_WAIT, 0);
+}
+
+static void dccp_handle_ackvec_processing(struct sock *sk, struct sk_buff *skb)
+{
+ struct dccp_ackvec *av = dccp_sk(sk)->dccps_hc_rx_ackvec;
+
+ if (av == NULL)
+ return;
+ if (DCCP_SKB_CB(skb)->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
+ dccp_ackvec_clear_state(av, DCCP_SKB_CB(skb)->dccpd_ack_seq);
+ dccp_ackvec_input(av, skb);
+}
+
+static void dccp_deliver_input_to_ccids(struct sock *sk, struct sk_buff *skb)
+{
+ const struct dccp_sock *dp = dccp_sk(sk);
+
+ /* Don't deliver to RX CCID when node has shut down read end. */
+ if (!(sk->sk_shutdown & RCV_SHUTDOWN))
+ ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb);
+ /*
+ * Until the TX queue has been drained, we can not honour SHUT_WR, since
+ * we need received feedback as input to adjust congestion control.
+ */
+ if (sk->sk_write_queue.qlen > 0 || !(sk->sk_shutdown & SEND_SHUTDOWN))
+ ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb);
+}
+
+static int dccp_check_seqno(struct sock *sk, struct sk_buff *skb)
+{
+ const struct dccp_hdr *dh = dccp_hdr(skb);
+ struct dccp_sock *dp = dccp_sk(sk);
+ u64 lswl, lawl, seqno = DCCP_SKB_CB(skb)->dccpd_seq,
+ ackno = DCCP_SKB_CB(skb)->dccpd_ack_seq;
+
+ /*
+ * Step 5: Prepare sequence numbers for Sync
+ * If P.type == Sync or P.type == SyncAck,
+ * If S.AWL <= P.ackno <= S.AWH and P.seqno >= S.SWL,
+ * / * P is valid, so update sequence number variables
+ * accordingly. After this update, P will pass the tests
+ * in Step 6. A SyncAck is generated if necessary in
+ * Step 15 * /
+ * Update S.GSR, S.SWL, S.SWH
+ * Otherwise,
+ * Drop packet and return
+ */
+ if (dh->dccph_type == DCCP_PKT_SYNC ||
+ dh->dccph_type == DCCP_PKT_SYNCACK) {
+ if (between48(ackno, dp->dccps_awl, dp->dccps_awh) &&
+ dccp_delta_seqno(dp->dccps_swl, seqno) >= 0)
+ dccp_update_gsr(sk, seqno);
+ else
+ return -1;
+ }
+
+ /*
+ * Step 6: Check sequence numbers
+ * Let LSWL = S.SWL and LAWL = S.AWL
+ * If P.type == CloseReq or P.type == Close or P.type == Reset,
+ * LSWL := S.GSR + 1, LAWL := S.GAR
+ * If LSWL <= P.seqno <= S.SWH
+ * and (P.ackno does not exist or LAWL <= P.ackno <= S.AWH),
+ * Update S.GSR, S.SWL, S.SWH
+ * If P.type != Sync,
+ * Update S.GAR
+ */
+ lswl = dp->dccps_swl;
+ lawl = dp->dccps_awl;
+
+ if (dh->dccph_type == DCCP_PKT_CLOSEREQ ||
+ dh->dccph_type == DCCP_PKT_CLOSE ||
+ dh->dccph_type == DCCP_PKT_RESET) {
+ lswl = ADD48(dp->dccps_gsr, 1);
+ lawl = dp->dccps_gar;
+ }
+
+ if (between48(seqno, lswl, dp->dccps_swh) &&
+ (ackno == DCCP_PKT_WITHOUT_ACK_SEQ ||
+ between48(ackno, lawl, dp->dccps_awh))) {
+ dccp_update_gsr(sk, seqno);
+
+ if (dh->dccph_type != DCCP_PKT_SYNC &&
+ ackno != DCCP_PKT_WITHOUT_ACK_SEQ &&
+ after48(ackno, dp->dccps_gar))
+ dp->dccps_gar = ackno;
+ } else {
+ unsigned long now = jiffies;
+ /*
+ * Step 6: Check sequence numbers
+ * Otherwise,
+ * If P.type == Reset,
+ * Send Sync packet acknowledging S.GSR
+ * Otherwise,
+ * Send Sync packet acknowledging P.seqno
+ * Drop packet and return
+ *
+ * These Syncs are rate-limited as per RFC 4340, 7.5.4:
+ * at most 1 / (dccp_sync_rate_limit * HZ) Syncs per second.
+ */
+ if (time_before(now, (dp->dccps_rate_last +
+ sysctl_dccp_sync_ratelimit)))
+ return -1;
+
+ DCCP_WARN("Step 6 failed for %s packet, "
+ "(LSWL(%llu) <= P.seqno(%llu) <= S.SWH(%llu)) and "
+ "(P.ackno %s or LAWL(%llu) <= P.ackno(%llu) <= S.AWH(%llu), "
+ "sending SYNC...\n", dccp_packet_name(dh->dccph_type),
+ (unsigned long long) lswl, (unsigned long long) seqno,
+ (unsigned long long) dp->dccps_swh,
+ (ackno == DCCP_PKT_WITHOUT_ACK_SEQ) ? "doesn't exist"
+ : "exists",
+ (unsigned long long) lawl, (unsigned long long) ackno,
+ (unsigned long long) dp->dccps_awh);
+
+ dp->dccps_rate_last = now;
+
+ if (dh->dccph_type == DCCP_PKT_RESET)
+ seqno = dp->dccps_gsr;
+ dccp_send_sync(sk, seqno, DCCP_PKT_SYNC);
+ return -1;
+ }
+
+ return 0;
+}
+
+static int __dccp_rcv_established(struct sock *sk, struct sk_buff *skb,
+ const struct dccp_hdr *dh, const unsigned int len)
+{
+ struct dccp_sock *dp = dccp_sk(sk);
+
+ switch (dccp_hdr(skb)->dccph_type) {
+ case DCCP_PKT_DATAACK:
+ case DCCP_PKT_DATA:
+ /*
+ * FIXME: schedule DATA_DROPPED (RFC 4340, 11.7.2) if and when
+ * - sk_shutdown == RCV_SHUTDOWN, use Code 1, "Not Listening"
+ * - sk_receive_queue is full, use Code 2, "Receive Buffer"
+ */
+ dccp_enqueue_skb(sk, skb);
+ return 0;
+ case DCCP_PKT_ACK:
+ goto discard;
+ case DCCP_PKT_RESET:
+ /*
+ * Step 9: Process Reset
+ * If P.type == Reset,
+ * Tear down connection
+ * S.state := TIMEWAIT
+ * Set TIMEWAIT timer
+ * Drop packet and return
+ */
+ dccp_rcv_reset(sk, skb);
+ return 0;
+ case DCCP_PKT_CLOSEREQ:
+ if (dccp_rcv_closereq(sk, skb))
+ return 0;
+ goto discard;
+ case DCCP_PKT_CLOSE:
+ if (dccp_rcv_close(sk, skb))
+ return 0;
+ goto discard;
+ case DCCP_PKT_REQUEST:
+ /* Step 7
+ * or (S.is_server and P.type == Response)
+ * or (S.is_client and P.type == Request)
+ * or (S.state >= OPEN and P.type == Request
+ * and P.seqno >= S.OSR)
+ * or (S.state >= OPEN and P.type == Response
+ * and P.seqno >= S.OSR)
+ * or (S.state == RESPOND and P.type == Data),
+ * Send Sync packet acknowledging P.seqno
+ * Drop packet and return
+ */
+ if (dp->dccps_role != DCCP_ROLE_LISTEN)
+ goto send_sync;
+ goto check_seq;
+ case DCCP_PKT_RESPONSE:
+ if (dp->dccps_role != DCCP_ROLE_CLIENT)
+ goto send_sync;
+check_seq:
+ if (dccp_delta_seqno(dp->dccps_osr,
+ DCCP_SKB_CB(skb)->dccpd_seq) >= 0) {
+send_sync:
+ dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq,
+ DCCP_PKT_SYNC);
+ }
+ break;
+ case DCCP_PKT_SYNC:
+ dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq,
+ DCCP_PKT_SYNCACK);
+ /*
+ * From RFC 4340, sec. 5.7
+ *
+ * As with DCCP-Ack packets, DCCP-Sync and DCCP-SyncAck packets
+ * MAY have non-zero-length application data areas, whose
+ * contents receivers MUST ignore.
+ */
+ goto discard;
+ }
+
+ DCCP_INC_STATS(DCCP_MIB_INERRS);
+discard:
+ __kfree_skb(skb);
+ return 0;
+}
+
+int dccp_rcv_established(struct sock *sk, struct sk_buff *skb,
+ const struct dccp_hdr *dh, const unsigned int len)
+{
+ if (dccp_check_seqno(sk, skb))
+ goto discard;
+
+ if (dccp_parse_options(sk, NULL, skb))
+ return 1;
+
+ dccp_handle_ackvec_processing(sk, skb);
+ dccp_deliver_input_to_ccids(sk, skb);
+
+ return __dccp_rcv_established(sk, skb, dh, len);
+discard:
+ __kfree_skb(skb);
+ return 0;
+}
+
+EXPORT_SYMBOL_GPL(dccp_rcv_established);
+
+static int dccp_rcv_request_sent_state_process(struct sock *sk,
+ struct sk_buff *skb,
+ const struct dccp_hdr *dh,
+ const unsigned int len)
+{
+ /*
+ * Step 4: Prepare sequence numbers in REQUEST
+ * If S.state == REQUEST,
+ * If (P.type == Response or P.type == Reset)
+ * and S.AWL <= P.ackno <= S.AWH,
+ * / * Set sequence number variables corresponding to the
+ * other endpoint, so P will pass the tests in Step 6 * /
+ * Set S.GSR, S.ISR, S.SWL, S.SWH
+ * / * Response processing continues in Step 10; Reset
+ * processing continues in Step 9 * /
+ */
+ if (dh->dccph_type == DCCP_PKT_RESPONSE) {
+ const struct inet_connection_sock *icsk = inet_csk(sk);
+ struct dccp_sock *dp = dccp_sk(sk);
+ long tstamp = dccp_timestamp();
+
+ if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
+ dp->dccps_awl, dp->dccps_awh)) {
+ dccp_pr_debug("invalid ackno: S.AWL=%llu, "
+ "P.ackno=%llu, S.AWH=%llu\n",
+ (unsigned long long)dp->dccps_awl,
+ (unsigned long long)DCCP_SKB_CB(skb)->dccpd_ack_seq,
+ (unsigned long long)dp->dccps_awh);
+ goto out_invalid_packet;
+ }
+
+ /*
+ * If option processing (Step 8) failed, return 1 here so that
+ * dccp_v4_do_rcv() sends a Reset. The Reset code depends on
+ * the option type and is set in dccp_parse_options().
+ */
+ if (dccp_parse_options(sk, NULL, skb))
+ return 1;
+
+ /* Obtain usec RTT sample from SYN exchange (used by TFRC). */
+ if (likely(dp->dccps_options_received.dccpor_timestamp_echo))
+ dp->dccps_syn_rtt = dccp_sample_rtt(sk, 10 * (tstamp -
+ dp->dccps_options_received.dccpor_timestamp_echo));
+
+ /* Stop the REQUEST timer */
+ inet_csk_clear_xmit_timer(sk, ICSK_TIME_RETRANS);
+ WARN_ON(sk->sk_send_head == NULL);
+ kfree_skb(sk->sk_send_head);
+ sk->sk_send_head = NULL;
+
+ /*
+ * Set ISR, GSR from packet. ISS was set in dccp_v{4,6}_connect
+ * and GSS in dccp_transmit_skb(). Setting AWL/AWH and SWL/SWH
+ * is done as part of activating the feature values below, since
+ * these settings depend on the local/remote Sequence Window
+ * features, which were undefined or not confirmed until now.
+ */
+ dp->dccps_gsr = dp->dccps_isr = DCCP_SKB_CB(skb)->dccpd_seq;
+
+ dccp_sync_mss(sk, icsk->icsk_pmtu_cookie);
+
+ /*
+ * Step 10: Process REQUEST state (second part)
+ * If S.state == REQUEST,
+ * / * If we get here, P is a valid Response from the
+ * server (see Step 4), and we should move to
+ * PARTOPEN state. PARTOPEN means send an Ack,
+ * don't send Data packets, retransmit Acks
+ * periodically, and always include any Init Cookie
+ * from the Response * /
+ * S.state := PARTOPEN
+ * Set PARTOPEN timer
+ * Continue with S.state == PARTOPEN
+ * / * Step 12 will send the Ack completing the
+ * three-way handshake * /
+ */
+ dccp_set_state(sk, DCCP_PARTOPEN);
+
+ /*
+ * If feature negotiation was successful, activate features now;
+ * an activation failure means that this host could not activate
+ * one ore more features (e.g. insufficient memory), which would
+ * leave at least one feature in an undefined state.
+ */
+ if (dccp_feat_activate_values(sk, &dp->dccps_featneg))
+ goto unable_to_proceed;
+
+ /* Make sure socket is routed, for correct metrics. */
+ icsk->icsk_af_ops->rebuild_header(sk);
+
+ if (!sock_flag(sk, SOCK_DEAD)) {
+ sk->sk_state_change(sk);
+ sk_wake_async(sk, SOCK_WAKE_IO, POLL_OUT);
+ }
+
+ if (sk->sk_write_pending || icsk->icsk_ack.pingpong ||
+ icsk->icsk_accept_queue.rskq_defer_accept) {
+ /* Save one ACK. Data will be ready after
+ * several ticks, if write_pending is set.
+ *
+ * It may be deleted, but with this feature tcpdumps
+ * look so _wonderfully_ clever, that I was not able
+ * to stand against the temptation 8) --ANK
+ */
+ /*
+ * OK, in DCCP we can as well do a similar trick, its
+ * even in the draft, but there is no need for us to
+ * schedule an ack here, as dccp_sendmsg does this for
+ * us, also stated in the draft. -acme
+ */
+ __kfree_skb(skb);
+ return 0;
+ }
+ dccp_send_ack(sk);
+ return -1;
+ }
+
+out_invalid_packet:
+ /* dccp_v4_do_rcv will send a reset */
+ DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR;
+ return 1;
+
+unable_to_proceed:
+ DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_ABORTED;
+ /*
+ * We mark this socket as no longer usable, so that the loop in
+ * dccp_sendmsg() terminates and the application gets notified.
+ */
+ dccp_set_state(sk, DCCP_CLOSED);
+ sk->sk_err = ECOMM;
+ return 1;
+}
+
+static int dccp_rcv_respond_partopen_state_process(struct sock *sk,
+ struct sk_buff *skb,
+ const struct dccp_hdr *dh,
+ const unsigned int len)
+{
+ struct dccp_sock *dp = dccp_sk(sk);
+ u32 sample = dp->dccps_options_received.dccpor_timestamp_echo;
+ int queued = 0;
+
+ switch (dh->dccph_type) {
+ case DCCP_PKT_RESET:
+ inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
+ break;
+ case DCCP_PKT_DATA:
+ if (sk->sk_state == DCCP_RESPOND)
+ break;
+ /* fall through */
+ case DCCP_PKT_DATAACK:
+ case DCCP_PKT_ACK:
+ /*
+ * FIXME: we should be resetting the PARTOPEN (DELACK) timer
+ * here but only if we haven't used the DELACK timer for
+ * something else, like sending a delayed ack for a TIMESTAMP
+ * echo, etc, for now were not clearing it, sending an extra
+ * ACK when there is nothing else to do in DELACK is not a big
+ * deal after all.
+ */
+
+ /* Stop the PARTOPEN timer */
+ if (sk->sk_state == DCCP_PARTOPEN)
+ inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
+
+ /* Obtain usec RTT sample from SYN exchange (used by TFRC). */
+ if (likely(sample)) {
+ long delta = dccp_timestamp() - sample;
+
+ dp->dccps_syn_rtt = dccp_sample_rtt(sk, 10 * delta);
+ }
+
+ dp->dccps_osr = DCCP_SKB_CB(skb)->dccpd_seq;
+ dccp_set_state(sk, DCCP_OPEN);
+
+ if (dh->dccph_type == DCCP_PKT_DATAACK ||
+ dh->dccph_type == DCCP_PKT_DATA) {
+ __dccp_rcv_established(sk, skb, dh, len);
+ queued = 1; /* packet was queued
+ (by __dccp_rcv_established) */
+ }
+ break;
+ }
+
+ return queued;
+}
+
+int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
+ struct dccp_hdr *dh, unsigned int len)
+{
+ struct dccp_sock *dp = dccp_sk(sk);
+ struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
+ const int old_state = sk->sk_state;
+ bool acceptable;
+ int queued = 0;
+
+ /*
+ * Step 3: Process LISTEN state
+ *
+ * If S.state == LISTEN,
+ * If P.type == Request or P contains a valid Init Cookie option,
+ * (* Must scan the packet's options to check for Init
+ * Cookies. Only Init Cookies are processed here,
+ * however; other options are processed in Step 8. This
+ * scan need only be performed if the endpoint uses Init
+ * Cookies *)
+ * (* Generate a new socket and switch to that socket *)
+ * Set S := new socket for this port pair
+ * S.state = RESPOND
+ * Choose S.ISS (initial seqno) or set from Init Cookies
+ * Initialize S.GAR := S.ISS
+ * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init
+ * Cookies Continue with S.state == RESPOND
+ * (* A Response packet will be generated in Step 11 *)
+ * Otherwise,
+ * Generate Reset(No Connection) unless P.type == Reset
+ * Drop packet and return
+ */
+ if (sk->sk_state == DCCP_LISTEN) {
+ if (dh->dccph_type == DCCP_PKT_REQUEST) {
+ /* It is possible that we process SYN packets from backlog,
+ * so we need to make sure to disable BH and RCU right there.
+ */
+ rcu_read_lock();
+ local_bh_disable();
+ acceptable = inet_csk(sk)->icsk_af_ops->conn_request(sk, skb) >= 0;
+ local_bh_enable();
+ rcu_read_unlock();
+ if (!acceptable)
+ return 1;
+ consume_skb(skb);
+ return 0;
+ }
+ if (dh->dccph_type == DCCP_PKT_RESET)
+ goto discard;
+
+ /* Caller (dccp_v4_do_rcv) will send Reset */
+ dcb->dccpd_reset_code = DCCP_RESET_CODE_NO_CONNECTION;
+ return 1;
+ } else if (sk->sk_state == DCCP_CLOSED) {
+ dcb->dccpd_reset_code = DCCP_RESET_CODE_NO_CONNECTION;
+ return 1;
+ }
+
+ /* Step 6: Check sequence numbers (omitted in LISTEN/REQUEST state) */
+ if (sk->sk_state != DCCP_REQUESTING && dccp_check_seqno(sk, skb))
+ goto discard;
+
+ /*
+ * Step 7: Check for unexpected packet types
+ * If (S.is_server and P.type == Response)
+ * or (S.is_client and P.type == Request)
+ * or (S.state == RESPOND and P.type == Data),
+ * Send Sync packet acknowledging P.seqno
+ * Drop packet and return
+ */
+ if ((dp->dccps_role != DCCP_ROLE_CLIENT &&
+ dh->dccph_type == DCCP_PKT_RESPONSE) ||
+ (dp->dccps_role == DCCP_ROLE_CLIENT &&
+ dh->dccph_type == DCCP_PKT_REQUEST) ||
+ (sk->sk_state == DCCP_RESPOND && dh->dccph_type == DCCP_PKT_DATA)) {
+ dccp_send_sync(sk, dcb->dccpd_seq, DCCP_PKT_SYNC);
+ goto discard;
+ }
+
+ /* Step 8: Process options */
+ if (dccp_parse_options(sk, NULL, skb))
+ return 1;
+
+ /*
+ * Step 9: Process Reset
+ * If P.type == Reset,
+ * Tear down connection
+ * S.state := TIMEWAIT
+ * Set TIMEWAIT timer
+ * Drop packet and return
+ */
+ if (dh->dccph_type == DCCP_PKT_RESET) {
+ dccp_rcv_reset(sk, skb);
+ return 0;
+ } else if (dh->dccph_type == DCCP_PKT_CLOSEREQ) { /* Step 13 */
+ if (dccp_rcv_closereq(sk, skb))
+ return 0;
+ goto discard;
+ } else if (dh->dccph_type == DCCP_PKT_CLOSE) { /* Step 14 */
+ if (dccp_rcv_close(sk, skb))
+ return 0;
+ goto discard;
+ }
+
+ switch (sk->sk_state) {
+ case DCCP_REQUESTING:
+ queued = dccp_rcv_request_sent_state_process(sk, skb, dh, len);
+ if (queued >= 0)
+ return queued;
+
+ __kfree_skb(skb);
+ return 0;
+
+ case DCCP_PARTOPEN:
+ /* Step 8: if using Ack Vectors, mark packet acknowledgeable */
+ dccp_handle_ackvec_processing(sk, skb);
+ dccp_deliver_input_to_ccids(sk, skb);
+ /* fall through */
+ case DCCP_RESPOND:
+ queued = dccp_rcv_respond_partopen_state_process(sk, skb,
+ dh, len);
+ break;
+ }
+
+ if (dh->dccph_type == DCCP_PKT_ACK ||
+ dh->dccph_type == DCCP_PKT_DATAACK) {
+ switch (old_state) {
+ case DCCP_PARTOPEN:
+ sk->sk_state_change(sk);
+ sk_wake_async(sk, SOCK_WAKE_IO, POLL_OUT);
+ break;
+ }
+ } else if (unlikely(dh->dccph_type == DCCP_PKT_SYNC)) {
+ dccp_send_sync(sk, dcb->dccpd_seq, DCCP_PKT_SYNCACK);
+ goto discard;
+ }
+
+ if (!queued) {
+discard:
+ __kfree_skb(skb);
+ }
+ return 0;
+}
+
+EXPORT_SYMBOL_GPL(dccp_rcv_state_process);
+
+/**
+ * dccp_sample_rtt - Validate and finalise computation of RTT sample
+ * @delta: number of microseconds between packet and acknowledgment
+ *
+ * The routine is kept generic to work in different contexts. It should be
+ * called immediately when the ACK used for the RTT sample arrives.
+ */
+u32 dccp_sample_rtt(struct sock *sk, long delta)
+{
+ /* dccpor_elapsed_time is either zeroed out or set and > 0 */
+ delta -= dccp_sk(sk)->dccps_options_received.dccpor_elapsed_time * 10;
+
+ if (unlikely(delta <= 0)) {
+ DCCP_WARN("unusable RTT sample %ld, using min\n", delta);
+ return DCCP_SANE_RTT_MIN;
+ }
+ if (unlikely(delta > DCCP_SANE_RTT_MAX)) {
+ DCCP_WARN("RTT sample %ld too large, using max\n", delta);
+ return DCCP_SANE_RTT_MAX;
+ }
+
+ return delta;
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-02 17:38:49 +0000