/*
* 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, DCCP_PKT_SYNC);
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, lawl;
/*
* 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
*/
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 = 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 {
LIMIT_NETDEBUG("Step 6 failed, sending SYNC...\n");
dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq, DCCP_PKT_SYNC);
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,
DCCP_PKT_SYNC);
}
break;
case DCCP_PKT_SYNC:
dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq,
DCCP_PKT_SYNCACK);
/*
* From the draft:
*
* 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_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,
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;
}
