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Commit | Line | Data |
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7c657876 ACM |
1 | /* |
2 | * net/dccp/timer.c | |
3 | * | |
4 | * An implementation of the DCCP protocol | |
5 | * Arnaldo Carvalho de Melo <acme@conectiva.com.br> | |
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 | ||
7c657876 ACM |
13 | #include <linux/dccp.h> |
14 | #include <linux/skbuff.h> | |
15 | ||
16 | #include "dccp.h" | |
17 | ||
2e2e9e92 GR |
18 | /* sysctl variables governing numbers of retransmission attempts */ |
19 | int sysctl_dccp_request_retries __read_mostly = TCP_SYN_RETRIES; | |
20 | int sysctl_dccp_retries1 __read_mostly = TCP_RETR1; | |
21 | int sysctl_dccp_retries2 __read_mostly = TCP_RETR2; | |
22 | ||
7c657876 ACM |
23 | static void dccp_write_timer(unsigned long data); |
24 | static void dccp_keepalive_timer(unsigned long data); | |
25 | static void dccp_delack_timer(unsigned long data); | |
26 | ||
27 | void dccp_init_xmit_timers(struct sock *sk) | |
28 | { | |
29 | inet_csk_init_xmit_timers(sk, &dccp_write_timer, &dccp_delack_timer, | |
30 | &dccp_keepalive_timer); | |
31 | } | |
32 | ||
33 | static void dccp_write_err(struct sock *sk) | |
34 | { | |
35 | sk->sk_err = sk->sk_err_soft ? : ETIMEDOUT; | |
36 | sk->sk_error_report(sk); | |
37 | ||
017487d7 | 38 | dccp_send_reset(sk, DCCP_RESET_CODE_ABORTED); |
7c657876 ACM |
39 | dccp_done(sk); |
40 | DCCP_INC_STATS_BH(DCCP_MIB_ABORTONTIMEOUT); | |
41 | } | |
42 | ||
43 | /* A write timeout has occurred. Process the after effects. */ | |
44 | static int dccp_write_timeout(struct sock *sk) | |
45 | { | |
46 | const struct inet_connection_sock *icsk = inet_csk(sk); | |
47 | int retry_until; | |
48 | ||
49 | if (sk->sk_state == DCCP_REQUESTING || sk->sk_state == DCCP_PARTOPEN) { | |
50 | if (icsk->icsk_retransmits != 0) | |
51 | dst_negative_advice(&sk->sk_dst_cache); | |
2e2e9e92 GR |
52 | retry_until = icsk->icsk_syn_retries ? |
53 | : sysctl_dccp_request_retries; | |
7c657876 | 54 | } else { |
2e2e9e92 | 55 | if (icsk->icsk_retransmits >= sysctl_dccp_retries1) { |
7690af3f ACM |
56 | /* NOTE. draft-ietf-tcpimpl-pmtud-01.txt requires pmtu |
57 | black hole detection. :-( | |
7c657876 ACM |
58 | |
59 | It is place to make it. It is not made. I do not want | |
60 | to make it. It is disguisting. It does not work in any | |
61 | case. Let me to cite the same draft, which requires for | |
62 | us to implement this: | |
63 | ||
64 | "The one security concern raised by this memo is that ICMP black holes | |
65 | are often caused by over-zealous security administrators who block | |
66 | all ICMP messages. It is vitally important that those who design and | |
67 | deploy security systems understand the impact of strict filtering on | |
68 | upper-layer protocols. The safest web site in the world is worthless | |
69 | if most TCP implementations cannot transfer data from it. It would | |
70 | be far nicer to have all of the black holes fixed rather than fixing | |
71 | all of the TCP implementations." | |
72 | ||
73 | Golden words :-). | |
74 | */ | |
75 | ||
76 | dst_negative_advice(&sk->sk_dst_cache); | |
77 | } | |
78 | ||
2e2e9e92 | 79 | retry_until = sysctl_dccp_retries2; |
7c657876 ACM |
80 | /* |
81 | * FIXME: see tcp_write_timout and tcp_out_of_resources | |
82 | */ | |
83 | } | |
84 | ||
85 | if (icsk->icsk_retransmits >= retry_until) { | |
86 | /* Has it gone just too far? */ | |
87 | dccp_write_err(sk); | |
88 | return 1; | |
89 | } | |
90 | return 0; | |
91 | } | |
92 | ||
93 | /* This is the same as tcp_delack_timer, sans prequeue & mem_reclaim stuff */ | |
94 | static void dccp_delack_timer(unsigned long data) | |
95 | { | |
96 | struct sock *sk = (struct sock *)data; | |
97 | struct inet_connection_sock *icsk = inet_csk(sk); | |
98 | ||
99 | bh_lock_sock(sk); | |
100 | if (sock_owned_by_user(sk)) { | |
101 | /* Try again later. */ | |
102 | icsk->icsk_ack.blocked = 1; | |
103 | NET_INC_STATS_BH(LINUX_MIB_DELAYEDACKLOCKED); | |
7690af3f ACM |
104 | sk_reset_timer(sk, &icsk->icsk_delack_timer, |
105 | jiffies + TCP_DELACK_MIN); | |
7c657876 ACM |
106 | goto out; |
107 | } | |
108 | ||
7690af3f ACM |
109 | if (sk->sk_state == DCCP_CLOSED || |
110 | !(icsk->icsk_ack.pending & ICSK_ACK_TIMER)) | |
7c657876 ACM |
111 | goto out; |
112 | if (time_after(icsk->icsk_ack.timeout, jiffies)) { | |
7690af3f ACM |
113 | sk_reset_timer(sk, &icsk->icsk_delack_timer, |
114 | icsk->icsk_ack.timeout); | |
7c657876 ACM |
115 | goto out; |
116 | } | |
117 | ||
118 | icsk->icsk_ack.pending &= ~ICSK_ACK_TIMER; | |
119 | ||
120 | if (inet_csk_ack_scheduled(sk)) { | |
121 | if (!icsk->icsk_ack.pingpong) { | |
122 | /* Delayed ACK missed: inflate ATO. */ | |
7690af3f ACM |
123 | icsk->icsk_ack.ato = min(icsk->icsk_ack.ato << 1, |
124 | icsk->icsk_rto); | |
7c657876 ACM |
125 | } else { |
126 | /* Delayed ACK missed: leave pingpong mode and | |
127 | * deflate ATO. | |
128 | */ | |
129 | icsk->icsk_ack.pingpong = 0; | |
130 | icsk->icsk_ack.ato = TCP_ATO_MIN; | |
131 | } | |
132 | dccp_send_ack(sk); | |
133 | NET_INC_STATS_BH(LINUX_MIB_DELAYEDACKS); | |
134 | } | |
135 | out: | |
136 | bh_unlock_sock(sk); | |
137 | sock_put(sk); | |
138 | } | |
139 | ||
140 | /* | |
141 | * The DCCP retransmit timer. | |
142 | */ | |
143 | static void dccp_retransmit_timer(struct sock *sk) | |
144 | { | |
145 | struct inet_connection_sock *icsk = inet_csk(sk); | |
146 | ||
afe00251 AB |
147 | /* retransmit timer is used for feature negotiation throughout |
148 | * connection. In this case, no packet is re-transmitted, but rather an | |
08a29e41 | 149 | * ack is generated and pending changes are placed into its options. |
afe00251 AB |
150 | */ |
151 | if (sk->sk_send_head == NULL) { | |
152 | dccp_pr_debug("feat negotiation retransmit timeout %p\n", sk); | |
153 | if (sk->sk_state == DCCP_OPEN) | |
154 | dccp_send_ack(sk); | |
155 | goto backoff; | |
156 | } | |
157 | ||
7c657876 ACM |
158 | /* |
159 | * sk->sk_send_head has to have one skb with | |
160 | * DCCP_SKB_CB(skb)->dccpd_type set to one of the retransmittable DCCP | |
08a29e41 GR |
161 | * packet types. The only packets eligible for retransmission are: |
162 | * -- Requests in client-REQUEST state (sec. 8.1.1) | |
163 | * -- Acks in client-PARTOPEN state (sec. 8.1.5) | |
164 | * -- CloseReq in server-CLOSEREQ state (sec. 8.3) | |
165 | * -- Close in node-CLOSING state (sec. 8.3) */ | |
7c657876 ACM |
166 | BUG_TRAP(sk->sk_send_head != NULL); |
167 | ||
168 | /* | |
169 | * More than than 4MSL (8 minutes) has passed, a RESET(aborted) was | |
170 | * sent, no need to retransmit, this sock is dead. | |
171 | */ | |
172 | if (dccp_write_timeout(sk)) | |
173 | goto out; | |
174 | ||
175 | /* | |
176 | * We want to know the number of packets retransmitted, not the | |
177 | * total number of retransmissions of clones of original packets. | |
178 | */ | |
179 | if (icsk->icsk_retransmits == 0) | |
180 | DCCP_INC_STATS_BH(DCCP_MIB_TIMEOUTS); | |
181 | ||
182 | if (dccp_retransmit_skb(sk, sk->sk_send_head) < 0) { | |
183 | /* | |
184 | * Retransmission failed because of local congestion, | |
185 | * do not backoff. | |
186 | */ | |
187 | if (icsk->icsk_retransmits == 0) | |
188 | icsk->icsk_retransmits = 1; | |
189 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, | |
190 | min(icsk->icsk_rto, | |
191 | TCP_RESOURCE_PROBE_INTERVAL), | |
7690af3f | 192 | DCCP_RTO_MAX); |
7c657876 ACM |
193 | goto out; |
194 | } | |
195 | ||
afe00251 | 196 | backoff: |
7c657876 ACM |
197 | icsk->icsk_backoff++; |
198 | icsk->icsk_retransmits++; | |
199 | ||
200 | icsk->icsk_rto = min(icsk->icsk_rto << 1, DCCP_RTO_MAX); | |
7690af3f ACM |
201 | inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, icsk->icsk_rto, |
202 | DCCP_RTO_MAX); | |
2e2e9e92 | 203 | if (icsk->icsk_retransmits > sysctl_dccp_retries1) |
7c657876 ACM |
204 | __sk_dst_reset(sk); |
205 | out:; | |
206 | } | |
207 | ||
208 | static void dccp_write_timer(unsigned long data) | |
209 | { | |
210 | struct sock *sk = (struct sock *)data; | |
211 | struct inet_connection_sock *icsk = inet_csk(sk); | |
212 | int event = 0; | |
213 | ||
214 | bh_lock_sock(sk); | |
215 | if (sock_owned_by_user(sk)) { | |
216 | /* Try again later */ | |
7690af3f ACM |
217 | sk_reset_timer(sk, &icsk->icsk_retransmit_timer, |
218 | jiffies + (HZ / 20)); | |
7c657876 ACM |
219 | goto out; |
220 | } | |
221 | ||
222 | if (sk->sk_state == DCCP_CLOSED || !icsk->icsk_pending) | |
223 | goto out; | |
224 | ||
225 | if (time_after(icsk->icsk_timeout, jiffies)) { | |
7690af3f ACM |
226 | sk_reset_timer(sk, &icsk->icsk_retransmit_timer, |
227 | icsk->icsk_timeout); | |
7c657876 ACM |
228 | goto out; |
229 | } | |
230 | ||
231 | event = icsk->icsk_pending; | |
232 | icsk->icsk_pending = 0; | |
233 | ||
234 | switch (event) { | |
235 | case ICSK_TIME_RETRANS: | |
236 | dccp_retransmit_timer(sk); | |
237 | break; | |
238 | } | |
239 | out: | |
240 | bh_unlock_sock(sk); | |
241 | sock_put(sk); | |
242 | } | |
243 | ||
244 | /* | |
245 | * Timer for listening sockets | |
246 | */ | |
247 | static void dccp_response_timer(struct sock *sk) | |
248 | { | |
7690af3f ACM |
249 | inet_csk_reqsk_queue_prune(sk, TCP_SYNQ_INTERVAL, DCCP_TIMEOUT_INIT, |
250 | DCCP_RTO_MAX); | |
7c657876 ACM |
251 | } |
252 | ||
253 | static void dccp_keepalive_timer(unsigned long data) | |
254 | { | |
255 | struct sock *sk = (struct sock *)data; | |
256 | ||
257 | /* Only process if socket is not in use. */ | |
258 | bh_lock_sock(sk); | |
259 | if (sock_owned_by_user(sk)) { | |
260 | /* Try again later. */ | |
261 | inet_csk_reset_keepalive_timer(sk, HZ / 20); | |
262 | goto out; | |
263 | } | |
264 | ||
265 | if (sk->sk_state == DCCP_LISTEN) { | |
266 | dccp_response_timer(sk); | |
267 | goto out; | |
268 | } | |
269 | out: | |
270 | bh_unlock_sock(sk); | |
271 | sock_put(sk); | |
272 | } |