[DCCP]: Simplified conditions due to use of enum:8 states
[linux-2.6.git] / net / dccp / minisocks.c
1 /*
2  *  net/dccp/minisocks.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
13 #include <linux/dccp.h>
14 #include <linux/kernel.h>
15 #include <linux/skbuff.h>
16 #include <linux/timer.h>
17
18 #include <net/sock.h>
19 #include <net/xfrm.h>
20 #include <net/inet_timewait_sock.h>
21
22 #include "ackvec.h"
23 #include "ccid.h"
24 #include "dccp.h"
25 #include "feat.h"
26
27 struct inet_timewait_death_row dccp_death_row = {
28         .sysctl_max_tw_buckets = NR_FILE * 2,
29         .period         = DCCP_TIMEWAIT_LEN / INET_TWDR_TWKILL_SLOTS,
30         .death_lock     = SPIN_LOCK_UNLOCKED,
31         .hashinfo       = &dccp_hashinfo,
32         .tw_timer       = TIMER_INITIALIZER(inet_twdr_hangman, 0,
33                                             (unsigned long)&dccp_death_row),
34         .twkill_work    = __WORK_INITIALIZER(dccp_death_row.twkill_work,
35                                              inet_twdr_twkill_work,
36                                              &dccp_death_row),
37 /* Short-time timewait calendar */
38
39         .twcal_hand     = -1,
40         .twcal_timer    = TIMER_INITIALIZER(inet_twdr_twcal_tick, 0,
41                                             (unsigned long)&dccp_death_row),
42 };
43
44 EXPORT_SYMBOL_GPL(dccp_death_row);
45
46 void dccp_time_wait(struct sock *sk, int state, int timeo)
47 {
48         struct inet_timewait_sock *tw = NULL;
49
50         if (dccp_death_row.tw_count < dccp_death_row.sysctl_max_tw_buckets)
51                 tw = inet_twsk_alloc(sk, state);
52
53         if (tw != NULL) {
54                 const struct inet_connection_sock *icsk = inet_csk(sk);
55                 const int rto = (icsk->icsk_rto << 2) - (icsk->icsk_rto >> 1);
56 #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
57                 if (tw->tw_family == PF_INET6) {
58                         const struct ipv6_pinfo *np = inet6_sk(sk);
59                         struct inet6_timewait_sock *tw6;
60
61                         tw->tw_ipv6_offset = inet6_tw_offset(sk->sk_prot);
62                         tw6 = inet6_twsk((struct sock *)tw);
63                         ipv6_addr_copy(&tw6->tw_v6_daddr, &np->daddr);
64                         ipv6_addr_copy(&tw6->tw_v6_rcv_saddr, &np->rcv_saddr);
65                         tw->tw_ipv6only = np->ipv6only;
66                 }
67 #endif
68                 /* Linkage updates. */
69                 __inet_twsk_hashdance(tw, sk, &dccp_hashinfo);
70
71                 /* Get the TIME_WAIT timeout firing. */
72                 if (timeo < rto)
73                         timeo = rto;
74
75                 tw->tw_timeout = DCCP_TIMEWAIT_LEN;
76                 if (state == DCCP_TIME_WAIT)
77                         timeo = DCCP_TIMEWAIT_LEN;
78
79                 inet_twsk_schedule(tw, &dccp_death_row, timeo,
80                                    DCCP_TIMEWAIT_LEN);
81                 inet_twsk_put(tw);
82         } else {
83                 /* Sorry, if we're out of memory, just CLOSE this
84                  * socket up.  We've got bigger problems than
85                  * non-graceful socket closings.
86                  */
87                 DCCP_WARN("time wait bucket table overflow\n");
88         }
89
90         dccp_done(sk);
91 }
92
93 struct sock *dccp_create_openreq_child(struct sock *sk,
94                                        const struct request_sock *req,
95                                        const struct sk_buff *skb)
96 {
97         /*
98          * Step 3: Process LISTEN state
99          *
100          *   (* Generate a new socket and switch to that socket *)
101          *   Set S := new socket for this port pair
102          */
103         struct sock *newsk = inet_csk_clone(sk, req, GFP_ATOMIC);
104
105         if (newsk != NULL) {
106                 const struct dccp_request_sock *dreq = dccp_rsk(req);
107                 struct inet_connection_sock *newicsk = inet_csk(sk);
108                 struct dccp_sock *newdp = dccp_sk(newsk);
109                 struct dccp_minisock *newdmsk = dccp_msk(newsk);
110
111                 newdp->dccps_role          = DCCP_ROLE_SERVER;
112                 newdp->dccps_hc_rx_ackvec  = NULL;
113                 newdp->dccps_service_list  = NULL;
114                 newdp->dccps_service       = dreq->dreq_service;
115                 newicsk->icsk_rto          = DCCP_TIMEOUT_INIT;
116                 do_gettimeofday(&newdp->dccps_epoch);
117
118                 if (dccp_feat_clone(sk, newsk))
119                         goto out_free;
120
121                 if (newdmsk->dccpms_send_ack_vector) {
122                         newdp->dccps_hc_rx_ackvec =
123                                                 dccp_ackvec_alloc(GFP_ATOMIC);
124                         if (unlikely(newdp->dccps_hc_rx_ackvec == NULL))
125                                 goto out_free;
126                 }
127
128                 newdp->dccps_hc_rx_ccid =
129                             ccid_hc_rx_new(newdmsk->dccpms_rx_ccid,
130                                            newsk, GFP_ATOMIC);
131                 newdp->dccps_hc_tx_ccid =
132                             ccid_hc_tx_new(newdmsk->dccpms_tx_ccid,
133                                            newsk, GFP_ATOMIC);
134                 if (unlikely(newdp->dccps_hc_rx_ccid == NULL ||
135                              newdp->dccps_hc_tx_ccid == NULL)) {
136                         dccp_ackvec_free(newdp->dccps_hc_rx_ackvec);
137                         ccid_hc_rx_delete(newdp->dccps_hc_rx_ccid, newsk);
138                         ccid_hc_tx_delete(newdp->dccps_hc_tx_ccid, newsk);
139 out_free:
140                         /* It is still raw copy of parent, so invalidate
141                          * destructor and make plain sk_free() */
142                         newsk->sk_destruct = NULL;
143                         sk_free(newsk);
144                         return NULL;
145                 }
146
147                 /*
148                  * Step 3: Process LISTEN state
149                  *
150                  *    Choose S.ISS (initial seqno) or set from Init Cookies
151                  *    Initialize S.GAR := S.ISS
152                  *    Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookies
153                  */
154
155                 /* See dccp_v4_conn_request */
156                 newdmsk->dccpms_sequence_window = req->rcv_wnd;
157
158                 newdp->dccps_gar = newdp->dccps_isr = dreq->dreq_isr;
159                 dccp_update_gsr(newsk, dreq->dreq_isr);
160
161                 newdp->dccps_iss = dreq->dreq_iss;
162                 dccp_update_gss(newsk, dreq->dreq_iss);
163
164                 /*
165                  * SWL and AWL are initially adjusted so that they are not less than
166                  * the initial Sequence Numbers received and sent, respectively:
167                  *      SWL := max(GSR + 1 - floor(W/4), ISR),
168                  *      AWL := max(GSS - W' + 1, ISS).
169                  * These adjustments MUST be applied only at the beginning of the
170                  * connection.
171                  */
172                 dccp_set_seqno(&newdp->dccps_swl,
173                                max48(newdp->dccps_swl, newdp->dccps_isr));
174                 dccp_set_seqno(&newdp->dccps_awl,
175                                max48(newdp->dccps_awl, newdp->dccps_iss));
176
177                 dccp_init_xmit_timers(newsk);
178
179                 DCCP_INC_STATS_BH(DCCP_MIB_PASSIVEOPENS);
180         }
181         return newsk;
182 }
183
184 EXPORT_SYMBOL_GPL(dccp_create_openreq_child);
185
186 /* 
187  * Process an incoming packet for RESPOND sockets represented
188  * as an request_sock.
189  */
190 struct sock *dccp_check_req(struct sock *sk, struct sk_buff *skb,
191                             struct request_sock *req,
192                             struct request_sock **prev)
193 {
194         struct sock *child = NULL;
195
196         /* Check for retransmitted REQUEST */
197         if (dccp_hdr(skb)->dccph_type == DCCP_PKT_REQUEST) {
198                 struct dccp_request_sock *dreq = dccp_rsk(req);
199
200                 if (after48(DCCP_SKB_CB(skb)->dccpd_seq, dreq->dreq_isr)) {
201                         dccp_pr_debug("Retransmitted REQUEST\n");
202                         dreq->dreq_isr = DCCP_SKB_CB(skb)->dccpd_seq;
203                         /*
204                          * Send another RESPONSE packet
205                          * To protect against Request floods, increment retrans
206                          * counter (backoff, monitored by dccp_response_timer).
207                          */
208                         req->retrans++;
209                         req->rsk_ops->rtx_syn_ack(sk, req, NULL);
210                 }
211                 /* Network Duplicate, discard packet */
212                 return NULL;
213         }
214
215         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR;
216
217         if (dccp_hdr(skb)->dccph_type != DCCP_PKT_ACK &&
218             dccp_hdr(skb)->dccph_type != DCCP_PKT_DATAACK)
219                 goto drop;
220
221         /* Invalid ACK */
222         if (DCCP_SKB_CB(skb)->dccpd_ack_seq != dccp_rsk(req)->dreq_iss) {
223                 dccp_pr_debug("Invalid ACK number: ack_seq=%llu, "
224                               "dreq_iss=%llu\n",
225                               (unsigned long long)
226                               DCCP_SKB_CB(skb)->dccpd_ack_seq,
227                               (unsigned long long)
228                               dccp_rsk(req)->dreq_iss);
229                 goto drop;
230         }
231
232         child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, req, NULL);
233         if (child == NULL)
234                 goto listen_overflow;
235
236         /* FIXME: deal with options */
237
238         inet_csk_reqsk_queue_unlink(sk, req, prev);
239         inet_csk_reqsk_queue_removed(sk, req);
240         inet_csk_reqsk_queue_add(sk, req, child);
241 out:
242         return child;
243 listen_overflow:
244         dccp_pr_debug("listen_overflow!\n");
245         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
246 drop:
247         if (dccp_hdr(skb)->dccph_type != DCCP_PKT_RESET)
248                 req->rsk_ops->send_reset(sk, skb);
249
250         inet_csk_reqsk_queue_drop(sk, req, prev);
251         goto out;
252 }
253
254 EXPORT_SYMBOL_GPL(dccp_check_req);
255
256 /*
257  *  Queue segment on the new socket if the new socket is active,
258  *  otherwise we just shortcircuit this and continue with
259  *  the new socket.
260  */
261 int dccp_child_process(struct sock *parent, struct sock *child,
262                        struct sk_buff *skb)
263 {
264         int ret = 0;
265         const int state = child->sk_state;
266
267         if (!sock_owned_by_user(child)) {
268                 ret = dccp_rcv_state_process(child, skb, dccp_hdr(skb),
269                                              skb->len);
270
271                 /* Wakeup parent, send SIGIO */
272                 if (state == DCCP_RESPOND && child->sk_state != state)
273                         parent->sk_data_ready(parent, 0);
274         } else {
275                 /* Alas, it is possible again, because we do lookup
276                  * in main socket hash table and lock on listening
277                  * socket does not protect us more.
278                  */
279                 sk_add_backlog(child, skb);
280         }
281
282         bh_unlock_sock(child);
283         sock_put(child);
284         return ret;
285 }
286
287 EXPORT_SYMBOL_GPL(dccp_child_process);
288
289 void dccp_reqsk_send_ack(struct sk_buff *skb, struct request_sock *rsk)
290 {
291         DCCP_BUG("DCCP-ACK packets are never sent in LISTEN/RESPOND state");
292 }
293
294 EXPORT_SYMBOL_GPL(dccp_reqsk_send_ack);
295
296 void dccp_reqsk_init(struct request_sock *req, struct sk_buff *skb)
297 {
298         inet_rsk(req)->rmt_port = dccp_hdr(skb)->dccph_sport;
299         inet_rsk(req)->acked    = 0;
300         req->rcv_wnd            = sysctl_dccp_feat_sequence_window;
301 }
302
303 EXPORT_SYMBOL_GPL(dccp_reqsk_init);