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         void            (*syn_ack_timeout)(struct sock *sk,
  49                                            struct request_sock *req);
  50 };
  51
  52 /* struct request_sock - mini sock to represent a connection request
  53  */
  54 struct request_sock {
  55         struct request_sock             *dl_next; /* Must be first member! */
  56         u16                             mss;
  57         u8                              retrans;
  58         u8                              cookie_ts; /* syncookie: encode tcpopts in timestamp */
  59         /* The following two fields can be easily recomputed I think -AK */
  60         u32                             window_clamp; /* window clamp at creation time */
  61         u32                             rcv_wnd;          /* rcv_wnd offered first time */
  62         u32                             ts_recent;
  63         unsigned long                   expires;
  64         const struct request_sock_ops   *rsk_ops;
  65         struct sock                     *sk;
  66         u32                             secid;
  67         u32                             peer_secid;
  68 };
  69
  70 static inline struct request_sock *reqsk_alloc(const struct request_sock_ops *ops)
  71 {
  72         struct request_sock *req = kmem_cache_alloc(ops->slab, GFP_ATOMIC);
  73
  74         if (req != NULL)
  75                 req->rsk_ops = ops;
  76
  77         return req;
  78 }
  79
  80 static inline void __reqsk_free(struct request_sock *req)
  81 {
  82         kmem_cache_free(req->rsk_ops->slab, req);
  83 }
  84
  85 static inline void reqsk_free(struct request_sock *req)
  86 {
  87         req->rsk_ops->destructor(req);
  88         __reqsk_free(req);
  89 }
  90
  91 extern int sysctl_max_syn_backlog;
  92
  93 /** struct listen_sock - listen state
  94  *
  95  * @max_qlen_log - log_2 of maximal queued SYNs/REQUESTs
  96  */
  97 struct listen_sock {
  98         u8                      max_qlen_log;
  99         /* 3 bytes hole, try to use */
 100         int                     qlen;
 101         int                     qlen_young;
 102         int                     clock_hand;
 103         u32                     hash_rnd;
 104         u32                     nr_table_entries;
 105         struct request_sock     *syn_table[0];
 106 };
 107
 108 /** struct request_sock_queue - queue of request_socks
 109  *
 110  * @rskq_accept_head - FIFO head of established children
 111  * @rskq_accept_tail - FIFO tail of established children
 112  * @rskq_defer_accept - User waits for some data after accept()
 113  * @syn_wait_lock - serializer
 114  *
 115  * %syn_wait_lock is necessary only to avoid proc interface having to grab the main
 116  * lock sock while browsing the listening hash (otherwise it's deadlock prone).
 117  *
 118  * This lock is acquired in read mode only from listening_get_next() seq_file
 119  * op and it's acquired in write mode _only_ from code that is actively
 120  * changing rskq_accept_head. All readers that are holding the master sock lock
 121  * don't need to grab this lock in read mode too as rskq_accept_head. writes
 122  * are always protected from the main sock lock.
 123  */
 124 struct request_sock_queue {
 125         struct request_sock     *rskq_accept_head;
 126         struct request_sock     *rskq_accept_tail;
 127         rwlock_t                syn_wait_lock;
 128         u8                      rskq_defer_accept;
 129         /* 3 bytes hole, try to pack */
 130         struct listen_sock      *listen_opt;
 131 };
 132
 133 extern int reqsk_queue_alloc(struct request_sock_queue *queue,
 134                              unsigned int nr_table_entries);
 135
 136 extern void __reqsk_queue_destroy(struct request_sock_queue *queue);
 137 extern void reqsk_queue_destroy(struct request_sock_queue *queue);
 138
 139 static inline struct request_sock *
 140         reqsk_queue_yank_acceptq(struct request_sock_queue *queue)
 141 {
 142         struct request_sock *req = queue->rskq_accept_head;
 143
 144         queue->rskq_accept_head = NULL;
 145         return req;
 146 }
 147
 148 static inline int reqsk_queue_empty(struct request_sock_queue *queue)
 149 {
 150         return queue->rskq_accept_head == NULL;
 151 }
 152
 153 static inline void reqsk_queue_unlink(struct request_sock_queue *queue,
 154                                       struct request_sock *req,
 155                                       struct request_sock **prev_req)
 156 {
 157         write_lock(&queue->syn_wait_lock);
 158         *prev_req = req->dl_next;
 159         write_unlock(&queue->syn_wait_lock);
 160 }
 161
 162 static inline void reqsk_queue_add(struct request_sock_queue *queue,
 163                                    struct request_sock *req,
 164                                    struct sock *parent,
 165                                    struct sock *child)
 166 {
 167         req->sk = child;
 168         sk_acceptq_added(parent);
 169
 170         if (queue->rskq_accept_head == NULL)
 171                 queue->rskq_accept_head = req;
 172         else
 173                 queue->rskq_accept_tail->dl_next = req;
 174
 175         queue->rskq_accept_tail = req;
 176         req->dl_next = NULL;
 177 }
 178
 179 static inline struct request_sock *reqsk_queue_remove(struct request_sock_queue *queue)
 180 {
 181         struct request_sock *req = queue->rskq_accept_head;
 182
 183         WARN_ON(req == NULL);
 184
 185         queue->rskq_accept_head = req->dl_next;
 186         if (queue->rskq_accept_head == NULL)
 187                 queue->rskq_accept_tail = NULL;
 188
 189         return req;
 190 }
 191
 192 static inline struct sock *reqsk_queue_get_child(struct request_sock_queue *queue,
 193                                                  struct sock *parent)
 194 {
 195         struct request_sock *req = reqsk_queue_remove(queue);
 196         struct sock *child = req->sk;
 197
 198         WARN_ON(child == NULL);
 199
 200         sk_acceptq_removed(parent);
 201         __reqsk_free(req);
 202         return child;
 203 }
 204
 205 static inline int reqsk_queue_removed(struct request_sock_queue *queue,
 206                                       struct request_sock *req)
 207 {
 208         struct listen_sock *lopt = queue->listen_opt;
 209
 210         if (req->retrans == 0)
 211                 --lopt->qlen_young;
 212
 213         return --lopt->qlen;
 214 }
 215
 216 static inline int reqsk_queue_added(struct request_sock_queue *queue)
 217 {
 218         struct listen_sock *lopt = queue->listen_opt;
 219         const int prev_qlen = lopt->qlen;
 220
 221         lopt->qlen_young++;
 222         lopt->qlen++;
 223         return prev_qlen;
 224 }
 225
 226 static inline int reqsk_queue_len(const struct request_sock_queue *queue)
 227 {
 228         return queue->listen_opt != NULL ? queue->listen_opt->qlen : 0;
 229 }
 230
 231 static inline int reqsk_queue_len_young(const struct request_sock_queue *queue)
 232 {
 233         return queue->listen_opt->qlen_young;
 234 }
 235
 236 static inline int reqsk_queue_is_full(const struct request_sock_queue *queue)
 237 {
 238         return queue->listen_opt->qlen >> queue->listen_opt->max_qlen_log;
 239 }
 240
 241 static inline void reqsk_queue_hash_req(struct request_sock_queue *queue,
 242                                         u32 hash, struct request_sock *req,
 243                                         unsigned long timeout)
 244 {
 245         struct listen_sock *lopt = queue->listen_opt;
 246
 247         req->expires = jiffies + timeout;
 248         req->retrans = 0;
 249         req->sk = NULL;
 250         req->dl_next = lopt->syn_table[hash];
 251
 252         write_lock(&queue->syn_wait_lock);
 253         lopt->syn_table[hash] = req;
 254         write_unlock(&queue->syn_wait_lock);
 255 }
 256
 257 #endif /* _REQUEST_SOCK_H */