projects/linux·blob v2.6.21 · refs

293 lines · 7.8 KiB

1/*
2 * net/dccp/timer.c
3 *
4 * An implementation of the DCCP protocol
5 * Arnaldo Carvalho de Melo <[email protected]>
6 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License
9 * as published by the Free Software Foundation; either version
10 * 2 of the License, or (at your option) any later version.
11 */
12
13#include <linux/dccp.h>
14#include <linux/skbuff.h>
15
16#include "dccp.h"
17
18/* sysctl variables governing numbers of retransmission attempts */
19int sysctl_dccp_request_retries __read_mostly = TCP_SYN_RETRIES;
20int sysctl_dccp_retries1 __read_mostly = TCP_RETR1;
21int sysctl_dccp_retries2 __read_mostly = TCP_RETR2;
22
23static void dccp_write_err(struct sock *sk)
24{
25 sk->sk_err = sk->sk_err_soft ? : ETIMEDOUT;
26 sk->sk_error_report(sk);
27
28 dccp_send_reset(sk, DCCP_RESET_CODE_ABORTED);
29 dccp_done(sk);
30 DCCP_INC_STATS_BH(DCCP_MIB_ABORTONTIMEOUT);
31}
32
33/* A write timeout has occurred. Process the after effects. */
34static int dccp_write_timeout(struct sock *sk)
35{
36 const struct inet_connection_sock *icsk = inet_csk(sk);
37 int retry_until;
38
39 if (sk->sk_state == DCCP_REQUESTING || sk->sk_state == DCCP_PARTOPEN) {
40 if (icsk->icsk_retransmits != 0)
41 dst_negative_advice(&sk->sk_dst_cache);
42 retry_until = icsk->icsk_syn_retries ?
43 : sysctl_dccp_request_retries;
44 } else {
45 if (icsk->icsk_retransmits >= sysctl_dccp_retries1) {
46 /* NOTE. draft-ietf-tcpimpl-pmtud-01.txt requires pmtu
47 black hole detection. :-(
48
49 It is place to make it. It is not made. I do not want
50 to make it. It is disguisting. It does not work in any
51 case. Let me to cite the same draft, which requires for
52 us to implement this:
53
54 "The one security concern raised by this memo is that ICMP black holes
55 are often caused by over-zealous security administrators who block
56 all ICMP messages. It is vitally important that those who design and
57 deploy security systems understand the impact of strict filtering on
58 upper-layer protocols. The safest web site in the world is worthless
59 if most TCP implementations cannot transfer data from it. It would
60 be far nicer to have all of the black holes fixed rather than fixing
61 all of the TCP implementations."
62
63 Golden words :-).
64 */
65
66 dst_negative_advice(&sk->sk_dst_cache);
67 }
68
69 retry_until = sysctl_dccp_retries2;
70 /*
71 * FIXME: see tcp_write_timout and tcp_out_of_resources
72 */
73 }
74
75 if (icsk->icsk_retransmits >= retry_until) {
76 /* Has it gone just too far? */
77 dccp_write_err(sk);
78 return 1;
79 }
80 return 0;
81}
82
83/*
84 * The DCCP retransmit timer.
85 */
86static void dccp_retransmit_timer(struct sock *sk)
87{
88 struct inet_connection_sock *icsk = inet_csk(sk);
89
90 /* retransmit timer is used for feature negotiation throughout
91 * connection. In this case, no packet is re-transmitted, but rather an
92 * ack is generated and pending changes are placed into its options.
93 */
94 if (sk->sk_send_head == NULL) {
95 dccp_pr_debug("feat negotiation retransmit timeout %p\n", sk);
96 if (sk->sk_state == DCCP_OPEN)
97 dccp_send_ack(sk);
98 goto backoff;
99 }
100
101 /*
102 * sk->sk_send_head has to have one skb with
103 * DCCP_SKB_CB(skb)->dccpd_type set to one of the retransmittable DCCP
104 * packet types. The only packets eligible for retransmission are:
105 * -- Requests in client-REQUEST state (sec. 8.1.1)
106 * -- Acks in client-PARTOPEN state (sec. 8.1.5)
107 * -- CloseReq in server-CLOSEREQ state (sec. 8.3)
108 * -- Close in node-CLOSING state (sec. 8.3) */
109 BUG_TRAP(sk->sk_send_head != NULL);
110
111 /*
112 * More than than 4MSL (8 minutes) has passed, a RESET(aborted) was
113 * sent, no need to retransmit, this sock is dead.
114 */
115 if (dccp_write_timeout(sk))
116 goto out;
117
118 /*
119 * We want to know the number of packets retransmitted, not the
120 * total number of retransmissions of clones of original packets.
121 */
122 if (icsk->icsk_retransmits == 0)
123 DCCP_INC_STATS_BH(DCCP_MIB_TIMEOUTS);
124
125 if (dccp_retransmit_skb(sk, sk->sk_send_head) < 0) {
126 /*
127 * Retransmission failed because of local congestion,
128 * do not backoff.
129 */
130 if (icsk->icsk_retransmits == 0)
131 icsk->icsk_retransmits = 1;
132 inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
133 min(icsk->icsk_rto,
134 TCP_RESOURCE_PROBE_INTERVAL),
135 DCCP_RTO_MAX);
136 goto out;
137 }
138
139backoff:
140 icsk->icsk_backoff++;
141 icsk->icsk_retransmits++;
142
143 icsk->icsk_rto = min(icsk->icsk_rto << 1, DCCP_RTO_MAX);
144 inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, icsk->icsk_rto,
145 DCCP_RTO_MAX);
146 if (icsk->icsk_retransmits > sysctl_dccp_retries1)
147 __sk_dst_reset(sk);
148out:;
149}
150
151static void dccp_write_timer(unsigned long data)
152{
153 struct sock *sk = (struct sock *)data;
154 struct inet_connection_sock *icsk = inet_csk(sk);
155 int event = 0;
156
157 bh_lock_sock(sk);
158 if (sock_owned_by_user(sk)) {
159 /* Try again later */
160 sk_reset_timer(sk, &icsk->icsk_retransmit_timer,
161 jiffies + (HZ / 20));
162 goto out;
163 }
164
165 if (sk->sk_state == DCCP_CLOSED || !icsk->icsk_pending)
166 goto out;
167
168 if (time_after(icsk->icsk_timeout, jiffies)) {
169 sk_reset_timer(sk, &icsk->icsk_retransmit_timer,
170 icsk->icsk_timeout);
171 goto out;
172 }
173
174 event = icsk->icsk_pending;
175 icsk->icsk_pending = 0;
176
177 switch (event) {
178 case ICSK_TIME_RETRANS:
179 dccp_retransmit_timer(sk);
180 break;
181 }
182out:
183 bh_unlock_sock(sk);
184 sock_put(sk);
185}
186
187/*
188 * Timer for listening sockets
189 */
190static void dccp_response_timer(struct sock *sk)
191{
192 inet_csk_reqsk_queue_prune(sk, TCP_SYNQ_INTERVAL, DCCP_TIMEOUT_INIT,
193 DCCP_RTO_MAX);
194}
195
196static void dccp_keepalive_timer(unsigned long data)
197{
198 struct sock *sk = (struct sock *)data;
199
200 /* Only process if socket is not in use. */
201 bh_lock_sock(sk);
202 if (sock_owned_by_user(sk)) {
203 /* Try again later. */
204 inet_csk_reset_keepalive_timer(sk, HZ / 20);
205 goto out;
206 }
207
208 if (sk->sk_state == DCCP_LISTEN) {
209 dccp_response_timer(sk);
210 goto out;
211 }
212out:
213 bh_unlock_sock(sk);
214 sock_put(sk);
215}
216
217/* This is the same as tcp_delack_timer, sans prequeue & mem_reclaim stuff */
218static void dccp_delack_timer(unsigned long data)
219{
220 struct sock *sk = (struct sock *)data;
221 struct inet_connection_sock *icsk = inet_csk(sk);
222
223 bh_lock_sock(sk);
224 if (sock_owned_by_user(sk)) {
225 /* Try again later. */
226 icsk->icsk_ack.blocked = 1;
227 NET_INC_STATS_BH(LINUX_MIB_DELAYEDACKLOCKED);
228 sk_reset_timer(sk, &icsk->icsk_delack_timer,
229 jiffies + TCP_DELACK_MIN);
230 goto out;
231 }
232
233 if (sk->sk_state == DCCP_CLOSED ||
234 !(icsk->icsk_ack.pending & ICSK_ACK_TIMER))
235 goto out;
236 if (time_after(icsk->icsk_ack.timeout, jiffies)) {
237 sk_reset_timer(sk, &icsk->icsk_delack_timer,
238 icsk->icsk_ack.timeout);
239 goto out;
240 }
241
242 icsk->icsk_ack.pending &= ~ICSK_ACK_TIMER;
243
244 if (inet_csk_ack_scheduled(sk)) {
245 if (!icsk->icsk_ack.pingpong) {
246 /* Delayed ACK missed: inflate ATO. */
247 icsk->icsk_ack.ato = min(icsk->icsk_ack.ato << 1,
248 icsk->icsk_rto);
249 } else {
250 /* Delayed ACK missed: leave pingpong mode and
251 * deflate ATO.
252 */
253 icsk->icsk_ack.pingpong = 0;
254 icsk->icsk_ack.ato = TCP_ATO_MIN;
255 }
256 dccp_send_ack(sk);
257 NET_INC_STATS_BH(LINUX_MIB_DELAYEDACKS);
258 }
259out:
260 bh_unlock_sock(sk);
261 sock_put(sk);
262}
263
264/* Transmit-delay timer: used by the CCIDs to delay actual send time */
265static void dccp_write_xmit_timer(unsigned long data)
266{
267 struct sock *sk = (struct sock *)data;
268 struct dccp_sock *dp = dccp_sk(sk);
269
270 bh_lock_sock(sk);
271 if (sock_owned_by_user(sk))
272 sk_reset_timer(sk, &dp->dccps_xmit_timer, jiffies+1);
273 else
274 dccp_write_xmit(sk, 0);
275 bh_unlock_sock(sk);
276 sock_put(sk);
277}
278
279static void dccp_init_write_xmit_timer(struct sock *sk)
280{
281 struct dccp_sock *dp = dccp_sk(sk);
282
283 init_timer(&dp->dccps_xmit_timer);
284 dp->dccps_xmit_timer.data = (unsigned long)sk;
285 dp->dccps_xmit_timer.function = dccp_write_xmit_timer;
286}
287
288void dccp_init_xmit_timers(struct sock *sk)
289{
290 dccp_init_write_xmit_timer(sk);
291 inet_csk_init_xmit_timers(sk, &dccp_write_timer, &dccp_delack_timer,
292 &dccp_keepalive_timer);
293}