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 struct 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  */
  46 struct 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
  62 static 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
  72 static inline void __reqsk_free(struct request_sock *req)
  73 {
  74         kmem_cache_free(req->rsk_ops->slab, req);
  75 }
  76
  77 static inline void reqsk_free(struct request_sock *req)
  78 {
  79         req->rsk_ops->destructor(req);
  80         __reqsk_free(req);
  81 }
  82
  83 extern 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  */
  89 struct 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  */
 116 struct 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
 125 extern int reqsk_queue_alloc(struct request_sock_queue *queue,
 126                              unsigned int nr_table_entries);
 127
 128 extern void __reqsk_queue_destroy(struct request_sock_queue *queue);
 129 extern void reqsk_queue_destroy(struct request_sock_queue *queue);
 130
 131 static 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
 140 static inline int reqsk_queue_empty(struct request_sock_queue *queue)
 141 {
 142         return queue->rskq_accept_head == NULL;
 143 }
 144
 145 static 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
 154 static 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
 171 static 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
 184 static 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
 197 static 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
 208 static 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
 218 static 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
 223 static inline int reqsk_queue_len_young(const struct request_sock_queue *queue)
 224 {
 225         return queue->listen_opt->qlen_young;
 226 }
 227
 228 static 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
 233 static 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 */