604 lines
17 KiB
C
604 lines
17 KiB
C
/*
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* net/dccp/input.c
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*
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* An implementation of the DCCP protocol
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* Arnaldo Carvalho de Melo <acme@conectiva.com.br>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/config.h>
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#include <linux/dccp.h>
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#include <linux/skbuff.h>
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#include <net/sock.h>
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#include "ccid.h"
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#include "dccp.h"
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static void dccp_fin(struct sock *sk, struct sk_buff *skb)
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{
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sk->sk_shutdown |= RCV_SHUTDOWN;
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sock_set_flag(sk, SOCK_DONE);
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__skb_pull(skb, dccp_hdr(skb)->dccph_doff * 4);
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__skb_queue_tail(&sk->sk_receive_queue, skb);
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skb_set_owner_r(skb, sk);
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sk->sk_data_ready(sk, 0);
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}
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static void dccp_rcv_close(struct sock *sk, struct sk_buff *skb)
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{
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switch (sk->sk_state) {
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case DCCP_PARTOPEN:
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case DCCP_OPEN:
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dccp_v4_send_reset(sk, DCCP_RESET_CODE_CLOSED);
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dccp_fin(sk, skb);
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dccp_set_state(sk, DCCP_CLOSED);
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break;
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}
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}
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static void dccp_rcv_closereq(struct sock *sk, struct sk_buff *skb)
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{
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/*
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* Step 7: Check for unexpected packet types
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* If (S.is_server and P.type == CloseReq)
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* Send Sync packet acknowledging P.seqno
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* Drop packet and return
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*/
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if (dccp_sk(sk)->dccps_role != DCCP_ROLE_CLIENT) {
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dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq, DCCP_PKT_SYNC);
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return;
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}
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switch (sk->sk_state) {
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case DCCP_PARTOPEN:
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case DCCP_OPEN:
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dccp_set_state(sk, DCCP_CLOSING);
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dccp_send_close(sk);
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break;
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}
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}
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static inline void dccp_event_ack_recv(struct sock *sk, struct sk_buff *skb)
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{
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struct dccp_sock *dp = dccp_sk(sk);
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if (dp->dccps_options.dccpo_send_ack_vector)
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dccp_ackpkts_check_rcv_ackno(dp->dccps_hc_rx_ackpkts, sk,
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DCCP_SKB_CB(skb)->dccpd_ack_seq);
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}
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static int dccp_check_seqno(struct sock *sk, struct sk_buff *skb)
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{
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const struct dccp_hdr *dh = dccp_hdr(skb);
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struct dccp_sock *dp = dccp_sk(sk);
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u64 lswl, lawl;
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/*
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* Step 5: Prepare sequence numbers for Sync
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* If P.type == Sync or P.type == SyncAck,
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* If S.AWL <= P.ackno <= S.AWH and P.seqno >= S.SWL,
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* / * P is valid, so update sequence number variables
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* accordingly. After this update, P will pass the tests
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* in Step 6. A SyncAck is generated if necessary in
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* Step 15 * /
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* Update S.GSR, S.SWL, S.SWH
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* Otherwise,
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* Drop packet and return
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*/
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if (dh->dccph_type == DCCP_PKT_SYNC ||
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dh->dccph_type == DCCP_PKT_SYNCACK) {
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if (between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
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dp->dccps_awl, dp->dccps_awh) &&
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!before48(DCCP_SKB_CB(skb)->dccpd_seq, dp->dccps_swl))
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dccp_update_gsr(sk, DCCP_SKB_CB(skb)->dccpd_seq);
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else
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return -1;
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}
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/*
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* Step 6: Check sequence numbers
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* Let LSWL = S.SWL and LAWL = S.AWL
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* If P.type == CloseReq or P.type == Close or P.type == Reset,
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* LSWL := S.GSR + 1, LAWL := S.GAR
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* If LSWL <= P.seqno <= S.SWH
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* and (P.ackno does not exist or LAWL <= P.ackno <= S.AWH),
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* Update S.GSR, S.SWL, S.SWH
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* If P.type != Sync,
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* Update S.GAR
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* Otherwise,
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* Send Sync packet acknowledging P.seqno
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* Drop packet and return
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*/
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lswl = dp->dccps_swl;
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lawl = dp->dccps_awl;
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if (dh->dccph_type == DCCP_PKT_CLOSEREQ ||
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dh->dccph_type == DCCP_PKT_CLOSE ||
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dh->dccph_type == DCCP_PKT_RESET) {
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lswl = dp->dccps_gsr;
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dccp_inc_seqno(&lswl);
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lawl = dp->dccps_gar;
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}
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if (between48(DCCP_SKB_CB(skb)->dccpd_seq, lswl, dp->dccps_swh) &&
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(DCCP_SKB_CB(skb)->dccpd_ack_seq == DCCP_PKT_WITHOUT_ACK_SEQ ||
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between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
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lawl, dp->dccps_awh))) {
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dccp_update_gsr(sk, DCCP_SKB_CB(skb)->dccpd_seq);
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if (dh->dccph_type != DCCP_PKT_SYNC &&
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(DCCP_SKB_CB(skb)->dccpd_ack_seq !=
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DCCP_PKT_WITHOUT_ACK_SEQ))
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dp->dccps_gar = DCCP_SKB_CB(skb)->dccpd_ack_seq;
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} else {
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LIMIT_NETDEBUG(KERN_WARNING "DCCP: Step 6 failed for %s packet, "
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"(LSWL(%llu) <= P.seqno(%llu) <= S.SWH(%llu)) and "
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"(P.ackno %s or LAWL(%llu) <= P.ackno(%llu) <= S.AWH(%llu), "
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"sending SYNC...\n",
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dccp_packet_name(dh->dccph_type),
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(unsigned long long) lswl,
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(unsigned long long)
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DCCP_SKB_CB(skb)->dccpd_seq,
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(unsigned long long) dp->dccps_swh,
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(DCCP_SKB_CB(skb)->dccpd_ack_seq ==
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DCCP_PKT_WITHOUT_ACK_SEQ) ? "doesn't exist" : "exists",
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(unsigned long long) lawl,
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(unsigned long long)
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DCCP_SKB_CB(skb)->dccpd_ack_seq,
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(unsigned long long) dp->dccps_awh);
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dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq, DCCP_PKT_SYNC);
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return -1;
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}
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return 0;
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}
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int dccp_rcv_established(struct sock *sk, struct sk_buff *skb,
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const struct dccp_hdr *dh, const unsigned len)
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{
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struct dccp_sock *dp = dccp_sk(sk);
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if (dccp_check_seqno(sk, skb))
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goto discard;
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if (dccp_parse_options(sk, skb))
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goto discard;
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if (DCCP_SKB_CB(skb)->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
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dccp_event_ack_recv(sk, skb);
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/*
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* FIXME: check ECN to see if we should use
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* DCCP_ACKPKTS_STATE_ECN_MARKED
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*/
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if (dp->dccps_options.dccpo_send_ack_vector) {
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struct dccp_ackpkts *ap = dp->dccps_hc_rx_ackpkts;
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if (dccp_ackpkts_add(dp->dccps_hc_rx_ackpkts,
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DCCP_SKB_CB(skb)->dccpd_seq,
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DCCP_ACKPKTS_STATE_RECEIVED)) {
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LIMIT_NETDEBUG(KERN_WARNING "DCCP: acknowledgeable "
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"packets buffer full!\n");
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ap->dccpap_ack_seqno = DCCP_MAX_SEQNO + 1;
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inet_csk_schedule_ack(sk);
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inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
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TCP_DELACK_MIN,
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DCCP_RTO_MAX);
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goto discard;
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}
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/*
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* FIXME: this activation is probably wrong, have to study more
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* TCP delack machinery and how it fits into DCCP draft, but
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* for now it kinda "works" 8)
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*/
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if (!inet_csk_ack_scheduled(sk)) {
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inet_csk_schedule_ack(sk);
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inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, 5 * HZ,
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DCCP_RTO_MAX);
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}
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}
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ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb);
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ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb);
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switch (dccp_hdr(skb)->dccph_type) {
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case DCCP_PKT_DATAACK:
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case DCCP_PKT_DATA:
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/*
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* FIXME: check if sk_receive_queue is full, schedule DATA_DROPPED
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* option if it is.
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*/
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__skb_pull(skb, dh->dccph_doff * 4);
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__skb_queue_tail(&sk->sk_receive_queue, skb);
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skb_set_owner_r(skb, sk);
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sk->sk_data_ready(sk, 0);
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return 0;
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case DCCP_PKT_ACK:
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goto discard;
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case DCCP_PKT_RESET:
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/*
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* Step 9: Process Reset
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* If P.type == Reset,
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* Tear down connection
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* S.state := TIMEWAIT
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* Set TIMEWAIT timer
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* Drop packet and return
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*/
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dccp_fin(sk, skb);
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dccp_time_wait(sk, DCCP_TIME_WAIT, 0);
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return 0;
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case DCCP_PKT_CLOSEREQ:
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dccp_rcv_closereq(sk, skb);
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goto discard;
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case DCCP_PKT_CLOSE:
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dccp_rcv_close(sk, skb);
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return 0;
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case DCCP_PKT_REQUEST:
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/* Step 7
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* or (S.is_server and P.type == Response)
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* or (S.is_client and P.type == Request)
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* or (S.state >= OPEN and P.type == Request
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* and P.seqno >= S.OSR)
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* or (S.state >= OPEN and P.type == Response
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* and P.seqno >= S.OSR)
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* or (S.state == RESPOND and P.type == Data),
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* Send Sync packet acknowledging P.seqno
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* Drop packet and return
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*/
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if (dp->dccps_role != DCCP_ROLE_LISTEN)
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goto send_sync;
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goto check_seq;
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case DCCP_PKT_RESPONSE:
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if (dp->dccps_role != DCCP_ROLE_CLIENT)
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goto send_sync;
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check_seq:
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if (!before48(DCCP_SKB_CB(skb)->dccpd_seq, dp->dccps_osr)) {
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send_sync:
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dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq,
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DCCP_PKT_SYNC);
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}
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break;
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case DCCP_PKT_SYNC:
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dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq,
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DCCP_PKT_SYNCACK);
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/*
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* From the draft:
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*
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* As with DCCP-Ack packets, DCCP-Sync and DCCP-SyncAck packets
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* MAY have non-zero-length application data areas, whose
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* contents * receivers MUST ignore.
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*/
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goto discard;
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}
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DCCP_INC_STATS_BH(DCCP_MIB_INERRS);
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discard:
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__kfree_skb(skb);
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return 0;
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}
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static int dccp_rcv_request_sent_state_process(struct sock *sk,
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struct sk_buff *skb,
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const struct dccp_hdr *dh,
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const unsigned len)
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{
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/*
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* Step 4: Prepare sequence numbers in REQUEST
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* If S.state == REQUEST,
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* If (P.type == Response or P.type == Reset)
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* and S.AWL <= P.ackno <= S.AWH,
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* / * Set sequence number variables corresponding to the
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* other endpoint, so P will pass the tests in Step 6 * /
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* Set S.GSR, S.ISR, S.SWL, S.SWH
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* / * Response processing continues in Step 10; Reset
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* processing continues in Step 9 * /
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*/
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if (dh->dccph_type == DCCP_PKT_RESPONSE) {
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const struct inet_connection_sock *icsk = inet_csk(sk);
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struct dccp_sock *dp = dccp_sk(sk);
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/* Stop the REQUEST timer */
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inet_csk_clear_xmit_timer(sk, ICSK_TIME_RETRANS);
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BUG_TRAP(sk->sk_send_head != NULL);
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__kfree_skb(sk->sk_send_head);
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sk->sk_send_head = NULL;
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if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
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dp->dccps_awl, dp->dccps_awh)) {
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dccp_pr_debug("invalid ackno: S.AWL=%llu, "
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"P.ackno=%llu, S.AWH=%llu \n",
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(unsigned long long)dp->dccps_awl,
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(unsigned long long)DCCP_SKB_CB(skb)->dccpd_ack_seq,
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(unsigned long long)dp->dccps_awh);
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goto out_invalid_packet;
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}
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dp->dccps_isr = DCCP_SKB_CB(skb)->dccpd_seq;
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dccp_update_gsr(sk, dp->dccps_isr);
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/*
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* SWL and AWL are initially adjusted so that they are not less than
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* the initial Sequence Numbers received and sent, respectively:
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* SWL := max(GSR + 1 - floor(W/4), ISR),
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* AWL := max(GSS - W' + 1, ISS).
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* These adjustments MUST be applied only at the beginning of the
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* connection.
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*
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* AWL was adjusted in dccp_v4_connect -acme
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*/
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dccp_set_seqno(&dp->dccps_swl,
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max48(dp->dccps_swl, dp->dccps_isr));
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if (ccid_hc_rx_init(dp->dccps_hc_rx_ccid, sk) != 0 ||
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ccid_hc_tx_init(dp->dccps_hc_tx_ccid, sk) != 0) {
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ccid_hc_rx_exit(dp->dccps_hc_rx_ccid, sk);
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ccid_hc_tx_exit(dp->dccps_hc_tx_ccid, sk);
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/* FIXME: send appropriate RESET code */
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goto out_invalid_packet;
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}
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dccp_sync_mss(sk, dp->dccps_pmtu_cookie);
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/*
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* Step 10: Process REQUEST state (second part)
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* If S.state == REQUEST,
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* / * If we get here, P is a valid Response from the
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* server (see Step 4), and we should move to
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* PARTOPEN state. PARTOPEN means send an Ack,
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* don't send Data packets, retransmit Acks
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* periodically, and always include any Init Cookie
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* from the Response * /
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* S.state := PARTOPEN
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* Set PARTOPEN timer
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* Continue with S.state == PARTOPEN
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* / * Step 12 will send the Ack completing the
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* three-way handshake * /
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*/
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dccp_set_state(sk, DCCP_PARTOPEN);
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/* Make sure socket is routed, for correct metrics. */
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inet_sk_rebuild_header(sk);
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if (!sock_flag(sk, SOCK_DEAD)) {
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sk->sk_state_change(sk);
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sk_wake_async(sk, 0, POLL_OUT);
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}
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if (sk->sk_write_pending || icsk->icsk_ack.pingpong ||
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icsk->icsk_accept_queue.rskq_defer_accept) {
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/* Save one ACK. Data will be ready after
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* several ticks, if write_pending is set.
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*
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* It may be deleted, but with this feature tcpdumps
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* look so _wonderfully_ clever, that I was not able
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* to stand against the temptation 8) --ANK
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*/
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/*
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* OK, in DCCP we can as well do a similar trick, its
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* even in the draft, but there is no need for us to
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* schedule an ack here, as dccp_sendmsg does this for
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* us, also stated in the draft. -acme
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*/
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__kfree_skb(skb);
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return 0;
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}
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dccp_send_ack(sk);
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return -1;
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}
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out_invalid_packet:
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return 1; /* dccp_v4_do_rcv will send a reset, but...
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FIXME: the reset code should be
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DCCP_RESET_CODE_PACKET_ERROR */
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}
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static int dccp_rcv_respond_partopen_state_process(struct sock *sk,
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struct sk_buff *skb,
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const struct dccp_hdr *dh,
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const unsigned len)
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{
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int queued = 0;
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switch (dh->dccph_type) {
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case DCCP_PKT_RESET:
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inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
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break;
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case DCCP_PKT_DATAACK:
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case DCCP_PKT_ACK:
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/*
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* FIXME: we should be reseting the PARTOPEN (DELACK) timer
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* here but only if we haven't used the DELACK timer for
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* something else, like sending a delayed ack for a TIMESTAMP
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* echo, etc, for now were not clearing it, sending an extra
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* ACK when there is nothing else to do in DELACK is not a big
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* deal after all.
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*/
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/* Stop the PARTOPEN timer */
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if (sk->sk_state == DCCP_PARTOPEN)
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inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
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dccp_sk(sk)->dccps_osr = DCCP_SKB_CB(skb)->dccpd_seq;
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dccp_set_state(sk, DCCP_OPEN);
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if (dh->dccph_type == DCCP_PKT_DATAACK) {
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dccp_rcv_established(sk, skb, dh, len);
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queued = 1; /* packet was queued
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(by dccp_rcv_established) */
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}
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break;
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}
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return queued;
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}
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int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
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struct dccp_hdr *dh, unsigned len)
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{
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struct dccp_sock *dp = dccp_sk(sk);
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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,
|
|
DCCP_PKT_SYNC);
|
|
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;
|
|
}
|