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1/*
2 * NET Generic infrastructure for Network protocols.
3 *
4 * Definitions for request_sock
5 *
6 * Authors: Arnaldo Carvalho de Melo <acme@conectiva.com.br>
7 *
8 * From code originally in include/net/tcp.h
9 *
10 * This program is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU General Public License
12 * as published by the Free Software Foundation; either version
13 * 2 of the License, or (at your option) any later version.
14 */
15#ifndef _REQUEST_SOCK_H
16#define _REQUEST_SOCK_H
17
18#include <linux/slab.h>
19#include <linux/spinlock.h>
20#include <linux/types.h>
21#include <linux/bug.h>
22
23#include <net/sock.h>
24
25struct request_sock;
26struct sk_buff;
27struct dst_entry;
28struct proto;
29
30struct request_sock_ops {
31 int family;
32 int obj_size;
33 struct kmem_cache *slab;
34 char *slab_name;
35 int (*rtx_syn_ack)(struct sock *sk,
36 struct request_sock *req);
37 void (*send_ack)(struct sock *sk, struct sk_buff *skb,
38 struct request_sock *req);
39 void (*send_reset)(struct sock *sk,
40 struct sk_buff *skb);
41 void (*destructor)(struct request_sock *req);
42};
43
44/* struct request_sock - mini sock to represent a connection request
45 */
46struct request_sock {
47 struct request_sock *dl_next; /* Must be first member! */
48 u16 mss;
49 u8 retrans;
50 u8 cookie_ts; /* syncookie: encode tcpopts in timestamp */
51 /* The following two fields can be easily recomputed I think -AK */
52 u32 window_clamp; /* window clamp at creation time */
53 u32 rcv_wnd; /* rcv_wnd offered first time */
54 u32 ts_recent;
55 unsigned long expires;
56 const struct request_sock_ops *rsk_ops;
57 struct sock *sk;
58 u32 secid;
59 u32 peer_secid;
60};
61
62static inline struct request_sock *reqsk_alloc(const struct request_sock_ops *ops)
63{
64 struct request_sock *req = kmem_cache_alloc(ops->slab, GFP_ATOMIC);
65
66 if (req != NULL)
67 req->rsk_ops = ops;
68
69 return req;
70}
71
72static inline void __reqsk_free(struct request_sock *req)
73{
74 kmem_cache_free(req->rsk_ops->slab, req);
75}
76
77static inline void reqsk_free(struct request_sock *req)
78{
79 req->rsk_ops->destructor(req);
80 __reqsk_free(req);
81}
82
83extern int sysctl_max_syn_backlog;
84
85/** struct listen_sock - listen state
86 *
87 * @max_qlen_log - log_2 of maximal queued SYNs/REQUESTs
88 */
89struct listen_sock {
90 u8 max_qlen_log;
91 /* 3 bytes hole, try to use */
92 int qlen;
93 int qlen_young;
94 int clock_hand;
95 u32 hash_rnd;
96 u32 nr_table_entries;
97 struct request_sock *syn_table[0];
98};
99
100/** struct request_sock_queue - queue of request_socks
101 *
102 * @rskq_accept_head - FIFO head of established children
103 * @rskq_accept_tail - FIFO tail of established children
104 * @rskq_defer_accept - User waits for some data after accept()
105 * @syn_wait_lock - serializer
106 *
107 * %syn_wait_lock is necessary only to avoid proc interface having to grab the main
108 * lock sock while browsing the listening hash (otherwise it's deadlock prone).
109 *
110 * This lock is acquired in read mode only from listening_get_next() seq_file
111 * op and it's acquired in write mode _only_ from code that is actively
112 * changing rskq_accept_head. All readers that are holding the master sock lock
113 * don't need to grab this lock in read mode too as rskq_accept_head. writes
114 * are always protected from the main sock lock.
115 */
116struct request_sock_queue {
117 struct request_sock *rskq_accept_head;
118 struct request_sock *rskq_accept_tail;
119 rwlock_t syn_wait_lock;
120 u8 rskq_defer_accept;
121 /* 3 bytes hole, try to pack */
122 struct listen_sock *listen_opt;
123};
124
125extern int reqsk_queue_alloc(struct request_sock_queue *queue,
126 unsigned int nr_table_entries);
127
128extern void __reqsk_queue_destroy(struct request_sock_queue *queue);
129extern void reqsk_queue_destroy(struct request_sock_queue *queue);
130
131static inline struct request_sock *
132 reqsk_queue_yank_acceptq(struct request_sock_queue *queue)
133{
134 struct request_sock *req = queue->rskq_accept_head;
135
136 queue->rskq_accept_head = NULL;
137 return req;
138}
139
140static inline int reqsk_queue_empty(struct request_sock_queue *queue)
141{
142 return queue->rskq_accept_head == NULL;
143}
144
145static inline void reqsk_queue_unlink(struct request_sock_queue *queue,
146 struct request_sock *req,
147 struct request_sock **prev_req)
148{
149 write_lock(&queue->syn_wait_lock);
150 *prev_req = req->dl_next;
151 write_unlock(&queue->syn_wait_lock);
152}
153
154static inline void reqsk_queue_add(struct request_sock_queue *queue,
155 struct request_sock *req,
156 struct sock *parent,
157 struct sock *child)
158{
159 req->sk = child;
160 sk_acceptq_added(parent);
161
162 if (queue->rskq_accept_head == NULL)
163 queue->rskq_accept_head = req;
164 else
165 queue->rskq_accept_tail->dl_next = req;
166
167 queue->rskq_accept_tail = req;
168 req->dl_next = NULL;
169}
170
171static inline struct request_sock *reqsk_queue_remove(struct request_sock_queue *queue)
172{
173 struct request_sock *req = queue->rskq_accept_head;
174
175 WARN_ON(req == NULL);
176
177 queue->rskq_accept_head = req->dl_next;
178 if (queue->rskq_accept_head == NULL)
179 queue->rskq_accept_tail = NULL;
180
181 return req;
182}
183
184static inline struct sock *reqsk_queue_get_child(struct request_sock_queue *queue,
185 struct sock *parent)
186{
187 struct request_sock *req = reqsk_queue_remove(queue);
188 struct sock *child = req->sk;
189
190 WARN_ON(child == NULL);
191
192 sk_acceptq_removed(parent);
193 __reqsk_free(req);
194 return child;
195}
196
197static inline int reqsk_queue_removed(struct request_sock_queue *queue,
198 struct request_sock *req)
199{
200 struct listen_sock *lopt = queue->listen_opt;
201
202 if (req->retrans == 0)
203 --lopt->qlen_young;
204
205 return --lopt->qlen;
206}
207
208static inline int reqsk_queue_added(struct request_sock_queue *queue)
209{
210 struct listen_sock *lopt = queue->listen_opt;
211 const int prev_qlen = lopt->qlen;
212
213 lopt->qlen_young++;
214 lopt->qlen++;
215 return prev_qlen;
216}
217
218static inline int reqsk_queue_len(const struct request_sock_queue *queue)
219{
220 return queue->listen_opt != NULL ? queue->listen_opt->qlen : 0;
221}
222
223static inline int reqsk_queue_len_young(const struct request_sock_queue *queue)
224{
225 return queue->listen_opt->qlen_young;
226}
227
228static inline int reqsk_queue_is_full(const struct request_sock_queue *queue)
229{
230 return queue->listen_opt->qlen >> queue->listen_opt->max_qlen_log;
231}
232
233static inline void reqsk_queue_hash_req(struct request_sock_queue *queue,
234 u32 hash, struct request_sock *req,
235 unsigned long timeout)
236{
237 struct listen_sock *lopt = queue->listen_opt;
238
239 req->expires = jiffies + timeout;
240 req->retrans = 0;
241 req->sk = NULL;
242 req->dl_next = lopt->syn_table[hash];
243
244 write_lock(&queue->syn_wait_lock);
245 lopt->syn_table[hash] = req;
246 write_unlock(&queue->syn_wait_lock);
247}
248
249#endif /* _REQUEST_SOCK_H */