--- /dev/null
+/*
+ * 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 "ackvec.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)
+{
+ dccp_send_reset(sk, DCCP_RESET_CODE_CLOSED);
+ dccp_fin(sk, skb);
+ dccp_set_state(sk, DCCP_CLOSED);
+ sk_wake_async(sk, 1, POLL_HUP);
+}
+
+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;
+ }
+
+ if (sk->sk_state != DCCP_CLOSING)
+ dccp_set_state(sk, DCCP_CLOSING);
+ dccp_send_close(sk, 0);
+}
+
+static void dccp_event_ack_recv(struct sock *sk, struct sk_buff *skb)
+{
+ struct dccp_sock *dp = dccp_sk(sk);
+
+ if (dccp_msk(sk)->dccpms_send_ack_vector)
+ dccp_ackvec_check_rcv_ackno(dp->dccps_hc_rx_ackvec, 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(KERN_WARNING "DCCP: Step 6 failed for %s packet, "
+ "(LSWL(%llu) <= P.seqno(%llu) <= S.SWH(%llu)) and "
+ "(P.ackno %s or LAWL(%llu) <= P.ackno(%llu) <= S.AWH(%llu), "
+ "sending SYNC...\n",
+ dccp_packet_name(dh->dccph_type),
+ (unsigned long long) lswl,
+ (unsigned long long)
+ DCCP_SKB_CB(skb)->dccpd_seq,
+ (unsigned long long) dp->dccps_swh,
+ (DCCP_SKB_CB(skb)->dccpd_ack_seq ==
+ DCCP_PKT_WITHOUT_ACK_SEQ) ? "doesn't exist" : "exists",
+ (unsigned long long) lawl,
+ (unsigned long long)
+ DCCP_SKB_CB(skb)->dccpd_ack_seq,
+ (unsigned long long) dp->dccps_awh);
+ dccp_send_sync(sk, DCCP_SKB_CB(skb)->dccpd_seq, DCCP_PKT_SYNC);
+ return -1;
+ }
+
+ return 0;
+}
+
+static 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);
+
+ 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;
+}
+
+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);
+
+ if (dccp_msk(sk)->dccpms_send_ack_vector &&
+ dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,
+ DCCP_SKB_CB(skb)->dccpd_seq,
+ DCCP_ACKVEC_STATE_RECEIVED))
+ goto discard;
+
+ ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb);
+ ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb);
+
+ return __dccp_rcv_established(sk, skb, dh, len);
+discard:
+ __kfree_skb(skb);
+ return 0;
+}
+
+EXPORT_SYMBOL_GPL(dccp_rcv_established);
+
+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;
+ }
+
+ if (dccp_parse_options(sk, skb))
+ goto out_invalid_packet;
+
+ if (dccp_msk(sk)->dccpms_send_ack_vector &&
+ dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,
+ DCCP_SKB_CB(skb)->dccpd_seq,
+ DCCP_ACKVEC_STATE_RECEIVED))
+ goto out_invalid_packet; /* FIXME: change error code */
+
+ dp->dccps_isr = DCCP_SKB_CB(skb)->dccpd_seq;
+ dccp_update_gsr(sk, dp->dccps_isr);
+ /*
+ * SWL and AWL are initially adjusted so that they are not less than
+ * the initial Sequence Numbers received and sent, respectively:
+ * SWL := max(GSR + 1 - floor(W/4), ISR),
+ * AWL := max(GSS - W' + 1, ISS).
+ * These adjustments MUST be applied only at the beginning of the
+ * connection.
+ *
+ * AWL was adjusted in dccp_v4_connect -acme
+ */
+ dccp_set_seqno(&dp->dccps_swl,
+ max48(dp->dccps_swl, dp->dccps_isr));
+
+ dccp_sync_mss(sk, icsk->icsk_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. */
+ icsk->icsk_af_ops->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:
+ /* dccp_v4_do_rcv will send a reset */
+ DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR;
+ return 1;
+}
+
+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_DATA:
+ if (sk->sk_state == DCCP_RESPOND)
+ 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 ||
+ dh->dccph_type == DCCP_PKT_DATA) {
+ __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);
+ struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
+ 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 (inet_csk(sk)->icsk_af_ops->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 */
+ dcb->dccpd_reset_code = DCCP_RESET_CODE_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 (dcb->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
+ dccp_event_ack_recv(sk, skb);
+
+ if (dccp_msk(sk)->dccpms_send_ack_vector &&
+ dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,
+ DCCP_SKB_CB(skb)->dccpd_seq,
+ DCCP_ACKVEC_STATE_RECEIVED))
+ goto discard;
+
+ ccid_hc_rx_packet_recv(dp->dccps_hc_rx_ccid, sk, skb);
+ ccid_hc_tx_packet_recv(dp->dccps_hc_tx_ccid, sk, skb);
+ }
+
+ /*
+ * 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, dcb->dccpd_seq, DCCP_PKT_SYNC);
+ goto discard;
+ } else if (dh->dccph_type == DCCP_PKT_CLOSEREQ) {
+ dccp_rcv_closereq(sk, skb);
+ goto discard;
+ } else if (dh->dccph_type == DCCP_PKT_CLOSE) {
+ dccp_rcv_close(sk, skb);
+ return 0;
+ }
+
+ if (unlikely(dh->dccph_type == DCCP_PKT_SYNC)) {
+ dccp_send_sync(sk, dcb->dccpd_seq, DCCP_PKT_SYNCACK);
+ goto discard;
+ }
+
+ switch (sk->sk_state) {
+ case DCCP_CLOSED:
+ dcb->dccpd_reset_code = DCCP_RESET_CODE_NO_CONNECTION;
+ 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;
+}
+
+EXPORT_SYMBOL_GPL(dccp_rcv_state_process);
git://git.onelab.eu / linux-2.6.git / blobdiff