| /* |
| * 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/config.h> |
| #include <linux/dccp.h> |
| #include <linux/skbuff.h> |
| |
| #include <net/sock.h> |
| |
| #include "ccid.h" |
| #include "dccp.h" |
| |
| static void dccp_fin(struct sock *sk, struct sk_buff *skb) |
| { |
| sk->sk_shutdown |= RCV_SHUTDOWN; |
| sock_set_flag(sk, SOCK_DONE); |
| __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, 0); |
| } |
| |
| static void dccp_rcv_close(struct sock *sk, struct sk_buff *skb) |
| { |
| switch (sk->sk_state) { |
| case DCCP_PARTOPEN: |
| case DCCP_OPEN: |
| dccp_v4_send_reset(sk, DCCP_RESET_CODE_CLOSED); |
| dccp_fin(sk, skb); |
| dccp_set_state(sk, DCCP_CLOSED); |
| break; |
| } |
| } |
| |
| static void dccp_rcv_closereq(struct sock *sk, struct sk_buff *skb) |
| { |
| /* |
| * 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); |
| return; |
| } |
| |
| switch (sk->sk_state) { |
| case DCCP_PARTOPEN: |
| case DCCP_OPEN: |
| dccp_set_state(sk, DCCP_CLOSING); |
| dccp_send_close(sk); |
| break; |
| } |
| } |
| |
| static inline void dccp_event_ack_recv(struct sock *sk, struct sk_buff *skb) |
| { |
| struct dccp_sock *dp = dccp_sk(sk); |
| |
| if (dp->dccps_options.dccpo_send_ack_vector) |
| dccp_ackpkts_check_rcv_ackno(dp->dccps_hc_rx_ackpkts, sk, |
| DCCP_SKB_CB(skb)->dccpd_ack_seq); |
| } |
| |
| 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 = dp->dccps_swl; |
| u64 lawl = dp->dccps_awl; |
| |
| /* |
| * 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(DCCP_SKB_CB(skb)->dccpd_ack_seq, |
| dp->dccps_awl, dp->dccps_awh) && |
| !before48(DCCP_SKB_CB(skb)->dccpd_seq, dp->dccps_swl)) |
| dccp_update_gsr(sk, DCCP_SKB_CB(skb)->dccpd_seq); |
| 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 |
| * Otherwise, |
| * Send Sync packet acknowledging P.seqno |
| * Drop packet and return |
| */ |
| } else if (dh->dccph_type == DCCP_PKT_CLOSEREQ || |
| dh->dccph_type == DCCP_PKT_CLOSE || |
| dh->dccph_type == DCCP_PKT_RESET) { |
| lswl = dp->dccps_gsr; |
| dccp_inc_seqno(&lswl); |
| lawl = dp->dccps_gar; |
| } |
| |
| if (between48(DCCP_SKB_CB(skb)->dccpd_seq, lswl, dp->dccps_swh) && |
| (DCCP_SKB_CB(skb)->dccpd_ack_seq == DCCP_PKT_WITHOUT_ACK_SEQ || |
| between48(DCCP_SKB_CB(skb)->dccpd_ack_seq, |
| lawl, dp->dccps_awh))) { |
| dccp_update_gsr(sk, DCCP_SKB_CB(skb)->dccpd_seq); |
| |
| if (dh->dccph_type != DCCP_PKT_SYNC && |
| (DCCP_SKB_CB(skb)->dccpd_ack_seq != |
| DCCP_PKT_WITHOUT_ACK_SEQ)) |
| dp->dccps_gar = DCCP_SKB_CB(skb)->dccpd_ack_seq; |
| } else { |
| dccp_pr_debug("Step 6 failed, sending SYNC...\n"); |
| dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq); |
| return -1; |
| } |
| |
| return 0; |
| } |
| |
| int dccp_rcv_established(struct sock *sk, struct sk_buff *skb, |
| const struct dccp_hdr *dh, const unsigned len) |
| { |
| struct dccp_sock *dp = dccp_sk(sk); |
| |
| if (dccp_check_seqno(sk, skb)) |
| goto discard; |
| |
| if (dccp_parse_options(sk, skb)) |
| goto discard; |
| |
| if (DCCP_SKB_CB(skb)->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ) |
| dccp_event_ack_recv(sk, skb); |
| |
| /* |
| * FIXME: check ECN to see if we should use |
| * DCCP_ACKPKTS_STATE_ECN_MARKED |
| */ |
| if (dp->dccps_options.dccpo_send_ack_vector) { |
| struct dccp_ackpkts *ap = dp->dccps_hc_rx_ackpkts; |
| |
| if (dccp_ackpkts_add(dp->dccps_hc_rx_ackpkts, |
| DCCP_SKB_CB(skb)->dccpd_seq, |
| DCCP_ACKPKTS_STATE_RECEIVED)) { |
| LIMIT_NETDEBUG(KERN_INFO "DCCP: acknowledgeable " |
| "packets buffer full!\n"); |
| ap->dccpap_ack_seqno = DCCP_MAX_SEQNO + 1; |
| inet_csk_schedule_ack(sk); |
| inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, |
| TCP_DELACK_MIN, |
| DCCP_RTO_MAX); |
| goto discard; |
| } |
| |
| /* |
| * FIXME: this activation is probably wrong, have to study more |
| * TCP delack machinery and how it fits into DCCP draft, but |
| * for now it kinda "works" 8) |
| */ |
| if (!inet_csk_ack_scheduled(sk)) { |
| inet_csk_schedule_ack(sk); |
| inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, 5 * HZ, |
| DCCP_RTO_MAX); |
| } |
| } |
| |
| ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb); |
| ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb); |
| |
| switch (dccp_hdr(skb)->dccph_type) { |
| case DCCP_PKT_DATAACK: |
| case DCCP_PKT_DATA: |
| /* |
| * FIXME: check if sk_receive_queue is full, schedule DATA_DROPPED |
| * option if it is. |
| */ |
| __skb_pull(skb, dh->dccph_doff * 4); |
| __skb_queue_tail(&sk->sk_receive_queue, skb); |
| skb_set_owner_r(skb, sk); |
| sk->sk_data_ready(sk, 0); |
| 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_fin(sk, skb); |
| dccp_time_wait(sk, DCCP_TIME_WAIT, 0); |
| return 0; |
| case DCCP_PKT_CLOSEREQ: |
| dccp_rcv_closereq(sk, skb); |
| goto discard; |
| case DCCP_PKT_CLOSE: |
| dccp_rcv_close(sk, skb); |
| return 0; |
| 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 (!before48(DCCP_SKB_CB(skb)->dccpd_seq, dp->dccps_osr)) { |
| send_sync: |
| dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq); |
| } |
| break; |
| } |
| |
| DCCP_INC_STATS_BH(DCCP_MIB_INERRS); |
| discard: |
| __kfree_skb(skb); |
| return 0; |
| } |
| |
| static int dccp_rcv_request_sent_state_process(struct sock *sk, |
| struct sk_buff *skb, |
| const struct dccp_hdr *dh, |
| const unsigned 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); |
| |
| /* Stop the REQUEST timer */ |
| inet_csk_clear_xmit_timer(sk, ICSK_TIME_RETRANS); |
| BUG_TRAP(sk->sk_send_head != NULL); |
| __kfree_skb(sk->sk_send_head); |
| sk->sk_send_head = NULL; |
| |
| 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; |
| } |
| |
| dp->dccps_isr = DCCP_SKB_CB(skb)->dccpd_seq; |
| dccp_update_gsr(sk, DCCP_SKB_CB(skb)->dccpd_seq); |
| |
| if (ccid_hc_rx_init(dp->dccps_hc_rx_ccid, sk) != 0 || |
| ccid_hc_tx_init(dp->dccps_hc_tx_ccid, sk) != 0) { |
| ccid_hc_rx_exit(dp->dccps_hc_rx_ccid, sk); |
| ccid_hc_tx_exit(dp->dccps_hc_tx_ccid, sk); |
| /* FIXME: send appropriate RESET code */ |
| goto out_invalid_packet; |
| } |
| |
| dccp_sync_mss(sk, dp->dccps_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); |
| |
| /* Make sure socket is routed, for correct metrics. */ |
| inet_sk_rebuild_header(sk); |
| |
| if (!sock_flag(sk, SOCK_DEAD)) { |
| sk->sk_state_change(sk); |
| sk_wake_async(sk, 0, 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: |
| return 1; /* dccp_v4_do_rcv will send a reset, but... |
| FIXME: the reset code should be |
| DCCP_RESET_CODE_PACKET_ERROR */ |
| } |
| |
| static int dccp_rcv_respond_partopen_state_process(struct sock *sk, |
| struct sk_buff *skb, |
| const struct dccp_hdr *dh, |
| const unsigned len) |
| { |
| int queued = 0; |
| |
| switch (dh->dccph_type) { |
| case DCCP_PKT_RESET: |
| inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK); |
| break; |
| case DCCP_PKT_DATAACK: |
| case DCCP_PKT_ACK: |
| /* |
| * FIXME: we should be reseting 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); |
| |
| dccp_sk(sk)->dccps_osr = DCCP_SKB_CB(skb)->dccpd_seq; |
| dccp_set_state(sk, DCCP_OPEN); |
| |
| if (dh->dccph_type == DCCP_PKT_DATAACK) { |
| 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 len) |
| { |
| struct dccp_sock *dp = dccp_sk(sk); |
| const int old_state = sk->sk_state; |
| int queued = 0; |
| |
| /* |
| * Step 3: Process LISTEN state |
| * (Continuing from dccp_v4_do_rcv and dccp_v6_do_rcv) |
| * |
| * 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 an Init |
| * Cookie. Only the Init Cookie is 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 Cookie |
| * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookie |
| * 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 |
| * |
| * NOTE: the check for the packet types is done in |
| * dccp_rcv_state_process |
| */ |
| if (sk->sk_state == DCCP_LISTEN) { |
| if (dh->dccph_type == DCCP_PKT_REQUEST) { |
| if (dccp_v4_conn_request(sk, skb) < 0) |
| return 1; |
| |
| /* FIXME: do congestion control initialization */ |
| goto discard; |
| } |
| if (dh->dccph_type == DCCP_PKT_RESET) |
| goto discard; |
| |
| /* Caller (dccp_v4_do_rcv) will send Reset(No Connection)*/ |
| return 1; |
| } |
| |
| if (sk->sk_state != DCCP_REQUESTING) { |
| if (dccp_check_seqno(sk, skb)) |
| goto discard; |
| |
| /* |
| * Step 8: Process options and mark acknowledgeable |
| */ |
| if (dccp_parse_options(sk, skb)) |
| goto discard; |
| |
| if (DCCP_SKB_CB(skb)->dccpd_ack_seq != |
| DCCP_PKT_WITHOUT_ACK_SEQ) |
| dccp_event_ack_recv(sk, skb); |
| |
| ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb); |
| ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb); |
| |
| /* |
| * FIXME: check ECN to see if we should use |
| * DCCP_ACKPKTS_STATE_ECN_MARKED |
| */ |
| if (dp->dccps_options.dccpo_send_ack_vector) { |
| if (dccp_ackpkts_add(dp->dccps_hc_rx_ackpkts, |
| DCCP_SKB_CB(skb)->dccpd_seq, |
| DCCP_ACKPKTS_STATE_RECEIVED)) |
| goto discard; |
| /* |
| * FIXME: this activation is probably wrong, have to |
| * study more TCP delack machinery and how it fits into |
| * DCCP draft, but for now it kinda "works" 8) |
| */ |
| if ((dp->dccps_hc_rx_ackpkts->dccpap_ack_seqno == |
| DCCP_MAX_SEQNO + 1) && |
| !inet_csk_ack_scheduled(sk)) { |
| inet_csk_schedule_ack(sk); |
| inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, |
| TCP_DELACK_MIN, |
| DCCP_RTO_MAX); |
| } |
| } |
| } |
| |
| /* |
| * 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) { |
| /* |
| * Queue the equivalent of TCP fin so that dccp_recvmsg |
| * exits the loop |
| */ |
| dccp_fin(sk, skb); |
| dccp_time_wait(sk, DCCP_TIME_WAIT, 0); |
| return 0; |
| /* |
| * Step 7: Check for unexpected packet types |
| * If (S.is_server and P.type == CloseReq) |
| * or (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 |
| */ |
| } else if ((dp->dccps_role != DCCP_ROLE_CLIENT && |
| (dh->dccph_type == DCCP_PKT_RESPONSE || |
| dh->dccph_type == DCCP_PKT_CLOSEREQ)) || |
| (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, DCCP_SKB_CB(skb)->dccpd_seq); |
| goto discard; |
| } |
| |
| switch (sk->sk_state) { |
| case DCCP_CLOSED: |
| return 1; |
| |
| case DCCP_REQUESTING: |
| /* FIXME: do congestion control initialization */ |
| |
| queued = dccp_rcv_request_sent_state_process(sk, skb, dh, len); |
| if (queued >= 0) |
| return queued; |
| |
| __kfree_skb(skb); |
| return 0; |
| |
| case DCCP_RESPOND: |
| case DCCP_PARTOPEN: |
| 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, 0, POLL_OUT); |
| break; |
| } |
| } |
| |
| if (!queued) { |
| discard: |
| __kfree_skb(skb); |
| } |
| return 0; |
| } |