include/net/request_sock.h

   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
  25 struct request_sock;
  26 struct sk_buff;
  27 struct dst_entry;
  28 struct proto;
  29
  30 /* empty to "strongly type" an otherwise void parameter.
  31  */
  32 struct request_values {
  33 };
  34
  35 struct request_sock_ops {
  36         int             family;
  37         int             obj_size;
  38         struct kmem_cache       *slab;
  39         char            *slab_name;
  40         int             (*rtx_syn_ack)(struct sock *sk,
  41                                        struct request_sock *req,
  42                                        struct request_values *rvp);
  43         void            (*send_ack)(struct sock *sk, struct sk_buff *skb,
  44                                     struct request_sock *req);
  45         void            (*send_reset)(struct sock *sk,
  46                                       struct sk_buff *skb);
  47         void            (*destructor)(struct request_sock *req);
  48 };
  49
  50 /* struct request_sock - mini sock to represent a connection request
  51  */
  52 struct request_sock {
  53         struct request_sock             *dl_next; /* Must be first member! */
  54         u16                             mss;
  55         u8                              retrans;
  56         u8                              cookie_ts; /* syncookie: encode tcpopts in timestamp */
  57         /* The following two fields can be easily recomputed I think -AK */
  58         u32                             window_clamp; /* window clamp at creation time */
  59         u32                             rcv_wnd;          /* rcv_wnd offered first time */
  60         u32                             ts_recent;
  61         unsigned long                   expires;
  62         const struct request_sock_ops   *rsk_ops;
  63         struct sock                     *sk;
  64         u32                             secid;
  65         u32                             peer_secid;
  66 };
  67
  68 static inline struct request_sock *reqsk_alloc(const struct request_sock_ops *ops)
  69 {
  70         struct request_sock *req = kmem_cache_alloc(ops->slab, GFP_ATOMIC);
  71
  72         if (req != NULL)
  73                 req->rsk_ops = ops;
  74
  75         return req;
  76 }
  77
  78 static inline void __reqsk_free(struct request_sock *req)
  79 {
  80         kmem_cache_free(req->rsk_ops->slab, req);
  81 }
  82
  83 static inline void reqsk_free(struct request_sock *req)
  84 {
  85         req->rsk_ops->destructor(req);
  86         __reqsk_free(req);
  87 }
  88
  89 extern int sysctl_max_syn_backlog;
  90
  91 /** struct listen_sock - listen state
  92  *
  93  * @max_qlen_log - log_2 of maximal queued SYNs/REQUESTs
  94  */
  95 struct listen_sock {
  96         u8                      max_qlen_log;
  97         /* 3 bytes hole, try to use */
  98         int                     qlen;
  99         int                     qlen_young;
 100         int                     clock_hand;
 101         u32                     hash_rnd;
 102         u32                     nr_table_entries;
 103         struct request_sock     *syn_table[0];
 104 };
 105
 106 /** struct request_sock_queue - queue of request_socks
 107  *
 108  * @rskq_accept_head - FIFO head of established children
 109  * @rskq_accept_tail - FIFO tail of established children
 110  * @rskq_defer_accept - User waits for some data after accept()
 111  * @syn_wait_lock - serializer
 112  *
 113  * %syn_wait_lock is necessary only to avoid proc interface having to grab the main
 114  * lock sock while browsing the listening hash (otherwise it's deadlock prone).
 115  *
 116  * This lock is acquired in read mode only from listening_get_next() seq_file
 117  * op and it's acquired in write mode _only_ from code that is actively
 118  * changing rskq_accept_head. All readers that are holding the master sock lock
 119  * don't need to grab this lock in read mode too as rskq_accept_head. writes
 120  * are always protected from the main sock lock.
 121  */
 122 struct request_sock_queue {
 123         struct request_sock     *rskq_accept_head;
 124         struct request_sock     *rskq_accept_tail;
 125         rwlock_t                syn_wait_lock;
 126         u8                      rskq_defer_accept;
 127         /* 3 bytes hole, try to pack */
 128         struct listen_sock      *listen_opt;
 129 };
 130
 131 extern int reqsk_queue_alloc(struct request_sock_queue *queue,
 132                              unsigned int nr_table_entries);
 133
 134 extern void __reqsk_queue_destroy(struct request_sock_queue *queue);
 135 extern void reqsk_queue_destroy(struct request_sock_queue *queue);
 136
 137 static inline struct request_sock *
 138         reqsk_queue_yank_acceptq(struct request_sock_queue *queue)
 139 {
 140         struct request_sock *req = queue->rskq_accept_head;
 141
 142         queue->rskq_accept_head = NULL;
 143         return req;
 144 }
 145
 146 static inline int reqsk_queue_empty(struct request_sock_queue *queue)
 147 {
 148         return queue->rskq_accept_head == NULL;
 149 }
 150
 151 static inline void reqsk_queue_unlink(struct request_sock_queue *queue,
 152                                       struct request_sock *req,
 153                                       struct request_sock **prev_req)
 154 {
 155         write_lock(&queue->syn_wait_lock);
 156         *prev_req = req->dl_next;
 157         write_unlock(&queue->syn_wait_lock);
 158 }
 159
 160 static inline void reqsk_queue_add(struct request_sock_queue *queue,
 161                                    struct request_sock *req,
 162                                    struct sock *parent,
 163                                    struct sock *child)
 164 {
 165         req->sk = child;
 166         sk_acceptq_added(parent);
 167
 168         if (queue->rskq_accept_head == NULL)
 169                 queue->rskq_accept_head = req;
 170         else
 171                 queue->rskq_accept_tail->dl_next = req;
 172
 173         queue->rskq_accept_tail = req;
 174         req->dl_next = NULL;
 175 }
 176
 177 static inline struct request_sock *reqsk_queue_remove(struct request_sock_queue *queue)
 178 {
 179         struct request_sock *req = queue->rskq_accept_head;
 180
 181         WARN_ON(req == NULL);
 182
 183         queue->rskq_accept_head = req->dl_next;
 184         if (queue->rskq_accept_head == NULL)
 185                 queue->rskq_accept_tail = NULL;
 186
 187         return req;
 188 }
 189
 190 static inline struct sock *reqsk_queue_get_child(struct request_sock_queue *queue,
 191                                                  struct sock *parent)
 192 {
 193         struct request_sock *req = reqsk_queue_remove(queue);
 194         struct sock *child = req->sk;
 195
 196         WARN_ON(child == NULL);
 197
 198         sk_acceptq_removed(parent);
 199         __reqsk_free(req);
 200         return child;
 201 }
 202
 203 static inline int reqsk_queue_removed(struct request_sock_queue *queue,
 204                                       struct request_sock *req)
 205 {
 206         struct listen_sock *lopt = queue->listen_opt;
 207
 208         if (req->retrans == 0)
 209                 --lopt->qlen_young;
 210
 211         return --lopt->qlen;
 212 }
 213
 214 static inline int reqsk_queue_added(struct request_sock_queue *queue)
 215 {
 216         struct listen_sock *lopt = queue->listen_opt;
 217         const int prev_qlen = lopt->qlen;
 218
 219         lopt->qlen_young++;
 220         lopt->qlen++;
 221         return prev_qlen;
 222 }
 223
 224 static inline int reqsk_queue_len(const struct request_sock_queue *queue)
 225 {
 226         return queue->listen_opt != NULL ? queue->listen_opt->qlen : 0;
 227 }
 228
 229 static inline int reqsk_queue_len_young(const struct request_sock_queue *queue)
 230 {
 231         return queue->listen_opt->qlen_young;
 232 }
 233
 234 static inline int reqsk_queue_is_full(const struct request_sock_queue *queue)
 235 {
 236         return queue->listen_opt->qlen >> queue->listen_opt->max_qlen_log;
 237 }
 238
 239 static inline void reqsk_queue_hash_req(struct request_sock_queue *queue,
 240                                         u32 hash, struct request_sock *req,
 241                                         unsigned long timeout)
 242 {
 243         struct listen_sock *lopt = queue->listen_opt;
 244
 245         req->expires = jiffies + timeout;
 246         req->retrans = 0;
 247         req->sk = NULL;
 248         req->dl_next = lopt->syn_table[hash];
 249
 250         write_lock(&queue->syn_wait_lock);
 251         lopt->syn_table[hash] = req;
 252         write_unlock(&queue->syn_wait_lock);
 253 }
 254
 255 #endif /* _REQUEST_SOCK_H */