1 files changed, 272 insertions, 0 deletions
diff --git a/net/dccp/timer.c b/net/dccp/timer.c
new file mode 100644
index 0000000000..b3255e87cc
--- /dev/null
+++ b/net/dccp/timer.c
@@ -0,0 +1,272 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  net/dccp/timer.c
+ *
+ *  An implementation of the DCCP protocol
+ *  Arnaldo Carvalho de Melo <acme@conectiva.com.br>
+ */
+
+#include <linux/dccp.h>
+#include <linux/skbuff.h>
+#include <linux/export.h>
+
+#include "dccp.h"
+
+/* sysctl variables governing numbers of retransmission attempts */
+int  sysctl_dccp_request_retries	__read_mostly = TCP_SYN_RETRIES;
+int  sysctl_dccp_retries1		__read_mostly = TCP_RETR1;
+int  sysctl_dccp_retries2		__read_mostly = TCP_RETR2;
+
+static void dccp_write_err(struct sock *sk)
+{
+	sk->sk_err = READ_ONCE(sk->sk_err_soft) ? : ETIMEDOUT;
+	sk_error_report(sk);
+
+	dccp_send_reset(sk, DCCP_RESET_CODE_ABORTED);
+	dccp_done(sk);
+	__DCCP_INC_STATS(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);
+		retry_until = icsk->icsk_syn_retries ?
+			    : sysctl_dccp_request_retries;
+	} else {
+		if (icsk->icsk_retransmits >= sysctl_dccp_retries1) {
+			/* 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);
+		}
+
+		retry_until = sysctl_dccp_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;
+}
+
+/*
+ *	The DCCP retransmit timer.
+ */
+static void dccp_retransmit_timer(struct sock *sk)
+{
+	struct inet_connection_sock *icsk = inet_csk(sk);
+
+	/*
+	 * More than 4MSL (8 minutes) has passed, a RESET(aborted) was
+	 * sent, no need to retransmit, this sock is dead.
+	 */
+	if (dccp_write_timeout(sk))
+		return;
+
+	/*
+	 * 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(DCCP_MIB_TIMEOUTS);
+
+	if (dccp_retransmit_skb(sk) != 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),
+					  DCCP_RTO_MAX);
+		return;
+	}
+
+	icsk->icsk_backoff++;
+
+	icsk->icsk_rto = min(icsk->icsk_rto << 1, DCCP_RTO_MAX);
+	inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, icsk->icsk_rto,
+				  DCCP_RTO_MAX);
+	if (icsk->icsk_retransmits > sysctl_dccp_retries1)
+		__sk_dst_reset(sk);
+}
+
+static void dccp_write_timer(struct timer_list *t)
+{
+	struct inet_connection_sock *icsk =
+			from_timer(icsk, t, icsk_retransmit_timer);
+	struct sock *sk = &icsk->icsk_inet.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);
+}
+
+static void dccp_keepalive_timer(struct timer_list *t)
+{
+	struct sock *sk = from_timer(sk, t, sk_timer);
+
+	pr_err("dccp should not use a keepalive timer !\n");
+	sock_put(sk);
+}
+
+/* This is the same as tcp_delack_timer, sans prequeue & mem_reclaim stuff */
+static void dccp_delack_timer(struct timer_list *t)
+{
+	struct inet_connection_sock *icsk =
+			from_timer(icsk, t, icsk_delack_timer);
+	struct sock *sk = &icsk->icsk_inet.sk;
+
+	bh_lock_sock(sk);
+	if (sock_owned_by_user(sk)) {
+		/* Try again later. */
+		__NET_INC_STATS(sock_net(sk), 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 (!inet_csk_in_pingpong_mode(sk)) {
+			/* 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.
+			 */
+			inet_csk_exit_pingpong_mode(sk);
+			icsk->icsk_ack.ato = TCP_ATO_MIN;
+		}
+		dccp_send_ack(sk);
+		__NET_INC_STATS(sock_net(sk), LINUX_MIB_DELAYEDACKS);
+	}
+out:
+	bh_unlock_sock(sk);
+	sock_put(sk);
+}
+
+/**
+ * dccp_write_xmitlet  -  Workhorse for CCID packet dequeueing interface
+ * @t: pointer to the tasklet associated with this handler
+ *
+ * See the comments above %ccid_dequeueing_decision for supported modes.
+ */
+static void dccp_write_xmitlet(struct tasklet_struct *t)
+{
+	struct dccp_sock *dp = from_tasklet(dp, t, dccps_xmitlet);
+	struct sock *sk = &dp->dccps_inet_connection.icsk_inet.sk;
+
+	bh_lock_sock(sk);
+	if (sock_owned_by_user(sk))
+		sk_reset_timer(sk, &dccp_sk(sk)->dccps_xmit_timer, jiffies + 1);
+	else
+		dccp_write_xmit(sk);
+	bh_unlock_sock(sk);
+	sock_put(sk);
+}
+
+static void dccp_write_xmit_timer(struct timer_list *t)
+{
+	struct dccp_sock *dp = from_timer(dp, t, dccps_xmit_timer);
+
+	dccp_write_xmitlet(&dp->dccps_xmitlet);
+}
+
+void dccp_init_xmit_timers(struct sock *sk)
+{
+	struct dccp_sock *dp = dccp_sk(sk);
+
+	tasklet_setup(&dp->dccps_xmitlet, dccp_write_xmitlet);
+	timer_setup(&dp->dccps_xmit_timer, dccp_write_xmit_timer, 0);
+	inet_csk_init_xmit_timers(sk, &dccp_write_timer, &dccp_delack_timer,
+				  &dccp_keepalive_timer);
+}
+
+static ktime_t dccp_timestamp_seed;
+/**
+ * dccp_timestamp  -  10s of microseconds time source
+ * Returns the number of 10s of microseconds since loading DCCP. This is native
+ * DCCP time difference format (RFC 4340, sec. 13).
+ * Please note: This will wrap around about circa every 11.9 hours.
+ */
+u32 dccp_timestamp(void)
+{
+	u64 delta = (u64)ktime_us_delta(ktime_get_real(), dccp_timestamp_seed);
+
+	do_div(delta, 10);
+	return delta;
+}
+EXPORT_SYMBOL_GPL(dccp_timestamp);
+
+void __init dccp_timestamping_init(void)
+{
+	dccp_timestamp_seed = ktime_get_real();
+}