diff options
Diffstat (limited to 'net/dccp/input.c')
| -rw-r--r-- | net/dccp/input.c | 510 |
1 files changed, 510 insertions, 0 deletions
diff --git a/net/dccp/input.c b/net/dccp/input.c new file mode 100644 index 00000000000..622e976a51f --- /dev/null +++ b/net/dccp/input.c @@ -0,0 +1,510 @@ +/* + * 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(pr_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, TCP_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, TCP_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", + dp->dccps_awl, DCCP_SKB_CB(skb)->dccpd_ack_seq, 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; + + if (sk->sk_state != DCCP_LISTEN && 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, TCP_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_LISTEN: + if (dh->dccph_type == DCCP_PKT_ACK || + dh->dccph_type == DCCP_PKT_DATAACK) + return 1; + + if (dh->dccph_type == DCCP_PKT_RESET) + goto discard; + + if (dh->dccph_type == DCCP_PKT_REQUEST) { + if (dccp_v4_conn_request(sk, skb) < 0) + return 1; + + /* FIXME: do congestion control initialization */ + goto discard; + } + goto discard; + + 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; +} |