diff options
Diffstat (limited to 'net/dccp/input.c')
| -rw-r--r-- | net/dccp/input.c | 739 |
1 files changed, 739 insertions, 0 deletions
diff --git a/net/dccp/input.c b/net/dccp/input.c new file mode 100644 index 000000000..2cbb757a8 --- /dev/null +++ b/net/dccp/input.c @@ -0,0 +1,739 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * net/dccp/input.c + * + * An implementation of the DCCP protocol + * Arnaldo Carvalho de Melo <acme@conectiva.com.br> + */ + +#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; + fallthrough; + 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); + fallthrough; + 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); + fallthrough; + 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 || inet_csk_in_pingpong_mode(sk) || + 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; + fallthrough; + 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); + fallthrough; + 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 + * @sk: socket structure + * @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; +} |