| /* |
| * 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 || 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; |
| /* 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; |
| } |