[DCCP]: Initial implementation
Development to this point was done on a subversion repository at:
http://oops.ghostprotocols.net:81/cgi-bin/viewcvs.cgi/dccp-2.6/
This repository will be kept at this site for the foreseable future,
so that interested parties can see the history of this code,
attributions, etc.
If I ever decide to take this offline I'll provide the full history at
some other suitable place.
Signed-off-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/dccp/input.c b/net/dccp/input.c
new file mode 100644
index 0000000..622e976
--- /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;
+}