net/dccp/timer.c - arm/linux - Git at Google

 /*
  *  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);

 	/* retransmit timer is used for feature negotiation throughout
 	 * connection.  In this case, no packet is re-transmitted, but rather an
 	 * ack is generated and pending changes are splaced into its options.
 	 */
 	if (sk->sk_send_head == NULL) {
 		dccp_pr_debug("feat negotiation retransmit timeout %p\n", sk);
 		if (sk->sk_state == DCCP_OPEN)
 			dccp_send_ack(sk);
 		goto backoff;
 	}

 	/*
 	 * 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 handshake
 	 * (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),
 					  DCCP_RTO_MAX);
 		goto out;
 	}

 backoff:
 	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,
 				  DCCP_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)
 {
 	inet_csk_reqsk_queue_prune(sk, TCP_SYNQ_INTERVAL, DCCP_TIMEOUT_INIT,
 				   DCCP_RTO_MAX);
 }

 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);
 }
	/*
	* 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);

	/* retransmit timer is used for feature negotiation throughout
	* connection. In this case, no packet is re-transmitted, but rather an
	* ack is generated and pending changes are splaced into its options.
	*/
	if (sk->sk_send_head == NULL) {
	dccp_pr_debug("feat negotiation retransmit timeout %p\n", sk);
	if (sk->sk_state == DCCP_OPEN)
	dccp_send_ack(sk);
	goto backoff;
	}

	/*
	* 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 handshake
	* (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),
	DCCP_RTO_MAX);
	goto out;
	}

	backoff:
	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,
	DCCP_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)
	{
	inet_csk_reqsk_queue_prune(sk, TCP_SYNQ_INTERVAL, DCCP_TIMEOUT_INIT,
	DCCP_RTO_MAX);
	}

	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);
	}