[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/timer.c b/net/dccp/timer.c
new file mode 100644
index 0000000..8c396ee
--- /dev/null
+++ b/net/dccp/timer.c
@@ -0,0 +1,249 @@
+/*
+ * net/dccp/timer.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 "dccp.h"
+
+static void dccp_write_timer(unsigned long data);
+static void dccp_keepalive_timer(unsigned long data);
+static void dccp_delack_timer(unsigned long data);
+
+void dccp_init_xmit_timers(struct sock *sk)
+{
+ inet_csk_init_xmit_timers(sk, &dccp_write_timer, &dccp_delack_timer,
+ &dccp_keepalive_timer);
+}
+
+static void dccp_write_err(struct sock *sk)
+{
+ sk->sk_err = sk->sk_err_soft ? : ETIMEDOUT;
+ sk->sk_error_report(sk);
+
+ dccp_v4_send_reset(sk, DCCP_RESET_CODE_ABORTED);
+ dccp_done(sk);
+ DCCP_INC_STATS_BH(DCCP_MIB_ABORTONTIMEOUT);
+}
+
+/* A write timeout has occurred. Process the after effects. */
+static int dccp_write_timeout(struct sock *sk)
+{
+ const struct inet_connection_sock *icsk = inet_csk(sk);
+ int retry_until;
+
+ if (sk->sk_state == DCCP_REQUESTING || sk->sk_state == DCCP_PARTOPEN) {
+ if (icsk->icsk_retransmits != 0)
+ dst_negative_advice(&sk->sk_dst_cache);
+ retry_until = icsk->icsk_syn_retries ? : /* FIXME! */ 3 /* FIXME! sysctl_tcp_syn_retries */;
+ } else {
+ if (icsk->icsk_retransmits >= /* FIXME! sysctl_tcp_retries1 */ 5 /* FIXME! */) {
+ /* NOTE. draft-ietf-tcpimpl-pmtud-01.txt requires pmtu black
+ hole detection. :-(
+
+ It is place to make it. It is not made. I do not want
+ to make it. It is disguisting. It does not work in any
+ case. Let me to cite the same draft, which requires for
+ us to implement this:
+
+ "The one security concern raised by this memo is that ICMP black holes
+ are often caused by over-zealous security administrators who block
+ all ICMP messages. It is vitally important that those who design and
+ deploy security systems understand the impact of strict filtering on
+ upper-layer protocols. The safest web site in the world is worthless
+ if most TCP implementations cannot transfer data from it. It would
+ be far nicer to have all of the black holes fixed rather than fixing
+ all of the TCP implementations."
+
+ Golden words :-).
+ */
+
+ dst_negative_advice(&sk->sk_dst_cache);
+ }
+
+ retry_until = /* FIXME! */ 15 /* FIXME! sysctl_tcp_retries2 */;
+ /*
+ * FIXME: see tcp_write_timout and tcp_out_of_resources
+ */
+ }
+
+ if (icsk->icsk_retransmits >= retry_until) {
+ /* Has it gone just too far? */
+ dccp_write_err(sk);
+ return 1;
+ }
+ return 0;
+}
+
+/* This is the same as tcp_delack_timer, sans prequeue & mem_reclaim stuff */
+static void dccp_delack_timer(unsigned long data)
+{
+ struct sock *sk = (struct sock *)data;
+ struct inet_connection_sock *icsk = inet_csk(sk);
+
+ bh_lock_sock(sk);
+ if (sock_owned_by_user(sk)) {
+ /* Try again later. */
+ icsk->icsk_ack.blocked = 1;
+ NET_INC_STATS_BH(LINUX_MIB_DELAYEDACKLOCKED);
+ sk_reset_timer(sk, &icsk->icsk_delack_timer, jiffies + TCP_DELACK_MIN);
+ goto out;
+ }
+
+ if (sk->sk_state == DCCP_CLOSED || !(icsk->icsk_ack.pending & ICSK_ACK_TIMER))
+ goto out;
+ if (time_after(icsk->icsk_ack.timeout, jiffies)) {
+ sk_reset_timer(sk, &icsk->icsk_delack_timer, icsk->icsk_ack.timeout);
+ goto out;
+ }
+
+ icsk->icsk_ack.pending &= ~ICSK_ACK_TIMER;
+
+ if (inet_csk_ack_scheduled(sk)) {
+ if (!icsk->icsk_ack.pingpong) {
+ /* Delayed ACK missed: inflate ATO. */
+ icsk->icsk_ack.ato = min(icsk->icsk_ack.ato << 1, icsk->icsk_rto);
+ } else {
+ /* Delayed ACK missed: leave pingpong mode and
+ * deflate ATO.
+ */
+ icsk->icsk_ack.pingpong = 0;
+ icsk->icsk_ack.ato = TCP_ATO_MIN;
+ }
+ dccp_send_ack(sk);
+ NET_INC_STATS_BH(LINUX_MIB_DELAYEDACKS);
+ }
+out:
+ bh_unlock_sock(sk);
+ sock_put(sk);
+}
+
+/*
+ * The DCCP retransmit timer.
+ */
+static void dccp_retransmit_timer(struct sock *sk)
+{
+ struct inet_connection_sock *icsk = inet_csk(sk);
+
+ /*
+ * sk->sk_send_head has to have one skb with
+ * DCCP_SKB_CB(skb)->dccpd_type set to one of the retransmittable DCCP
+ * packet types (REQUEST, RESPONSE, the ACK in the 3way hanshake
+ * (PARTOPEN timer), etc).
+ */
+ BUG_TRAP(sk->sk_send_head != NULL);
+
+ /*
+ * More than than 4MSL (8 minutes) has passed, a RESET(aborted) was
+ * sent, no need to retransmit, this sock is dead.
+ */
+ if (dccp_write_timeout(sk))
+ goto out;
+
+ /*
+ * We want to know the number of packets retransmitted, not the
+ * total number of retransmissions of clones of original packets.
+ */
+ if (icsk->icsk_retransmits == 0)
+ DCCP_INC_STATS_BH(DCCP_MIB_TIMEOUTS);
+
+ if (dccp_retransmit_skb(sk, sk->sk_send_head) < 0) {
+ /*
+ * Retransmission failed because of local congestion,
+ * do not backoff.
+ */
+ if (icsk->icsk_retransmits == 0)
+ icsk->icsk_retransmits = 1;
+ inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
+ min(icsk->icsk_rto,
+ TCP_RESOURCE_PROBE_INTERVAL),
+ TCP_RTO_MAX);
+ goto out;
+ }
+
+ icsk->icsk_backoff++;
+ icsk->icsk_retransmits++;
+
+ icsk->icsk_rto = min(icsk->icsk_rto << 1, DCCP_RTO_MAX);
+ inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, icsk->icsk_rto, TCP_RTO_MAX);
+ if (icsk->icsk_retransmits > 3 /* FIXME: sysctl_dccp_retries1 */)
+ __sk_dst_reset(sk);
+out:;
+}
+
+static void dccp_write_timer(unsigned long data)
+{
+ struct sock *sk = (struct sock *)data;
+ struct inet_connection_sock *icsk = inet_csk(sk);
+ int event = 0;
+
+ bh_lock_sock(sk);
+ if (sock_owned_by_user(sk)) {
+ /* Try again later */
+ sk_reset_timer(sk, &icsk->icsk_retransmit_timer, jiffies + (HZ / 20));
+ goto out;
+ }
+
+ if (sk->sk_state == DCCP_CLOSED || !icsk->icsk_pending)
+ goto out;
+
+ if (time_after(icsk->icsk_timeout, jiffies)) {
+ sk_reset_timer(sk, &icsk->icsk_retransmit_timer, icsk->icsk_timeout);
+ goto out;
+ }
+
+ event = icsk->icsk_pending;
+ icsk->icsk_pending = 0;
+
+ switch (event) {
+ case ICSK_TIME_RETRANS:
+ dccp_retransmit_timer(sk);
+ break;
+ }
+out:
+ bh_unlock_sock(sk);
+ sock_put(sk);
+}
+
+/*
+ * Timer for listening sockets
+ */
+static void dccp_response_timer(struct sock *sk)
+{
+ struct inet_connection_sock *icsk = inet_csk(sk);
+ const int max_retries = icsk->icsk_syn_retries ? : TCP_SYNACK_RETRIES /* FIXME sysctl_tcp_synack_retries */;
+
+ reqsk_queue_prune(&icsk->icsk_accept_queue, sk, TCP_SYNQ_INTERVAL,
+ DCCP_TIMEOUT_INIT, DCCP_RTO_MAX, max_retries);
+}
+
+static void dccp_keepalive_timer(unsigned long data)
+{
+ struct sock *sk = (struct sock *)data;
+
+ /* Only process if socket is not in use. */
+ bh_lock_sock(sk);
+ if (sock_owned_by_user(sk)) {
+ /* Try again later. */
+ inet_csk_reset_keepalive_timer(sk, HZ / 20);
+ goto out;
+ }
+
+ if (sk->sk_state == DCCP_LISTEN) {
+ dccp_response_timer(sk);
+ goto out;
+ }
+out:
+ bh_unlock_sock(sk);
+ sock_put(sk);
+}
