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         u8                      synflood_warned;
 100         /* 2 bytes hole, try to use */
 101         int                     qlen;
 102         int                     qlen_young;
 103         int                     clock_hand;
 104         u32                     hash_rnd;
 105         u32                     nr_table_entries;
 106         struct request_sock     *syn_table[0];
 107 };
 108
 109 /** struct request_sock_queue - queue of request_socks
 110  *
 111  * @rskq_accept_head - FIFO head of established children
 112  * @rskq_accept_tail - FIFO tail of established children
 113  * @rskq_defer_accept - User waits for some data after accept()
 114  * @syn_wait_lock - serializer
 115  *
 116  * %syn_wait_lock is necessary only to avoid proc interface having to grab the main
 117  * lock sock while browsing the listening hash (otherwise it's deadlock prone).
 118  *
 119  * This lock is acquired in read mode only from listening_get_next() seq_file
 120  * op and it's acquired in write mode _only_ from code that is actively
 121  * changing rskq_accept_head. All readers that are holding the master sock lock
 122  * don't need to grab this lock in read mode too as rskq_accept_head. writes
 123  * are always protected from the main sock lock.
 124  */
 125 struct request_sock_queue {
 126         struct request_sock     *rskq_accept_head;
 127         struct request_sock     *rskq_accept_tail;
 128         rwlock_t                syn_wait_lock;
 129         u8                      rskq_defer_accept;
 130         /* 3 bytes hole, try to pack */
 131         struct listen_sock      *listen_opt;
 132 };
 133
 134 extern int reqsk_queue_alloc(struct request_sock_queue *queue,
 135                              unsigned int nr_table_entries);
 136
 137 extern void __reqsk_queue_destroy(struct request_sock_queue *queue);
 138 extern void reqsk_queue_destroy(struct request_sock_queue *queue);
 139
 140 static inline struct request_sock *
 141         reqsk_queue_yank_acceptq(struct request_sock_queue *queue)
 142 {
 143         struct request_sock *req = queue->rskq_accept_head;
 144
 145         queue->rskq_accept_head = NULL;
 146         return req;
 147 }
 148
 149 static inline int reqsk_queue_empty(struct request_sock_queue *queue)
 150 {
 151         return queue->rskq_accept_head == NULL;
 152 }
 153
 154 static inline void reqsk_queue_unlink(struct request_sock_queue *queue,
 155                                       struct request_sock *req,
 156                                       struct request_sock **prev_req)
 157 {
 158         write_lock(&queue->syn_wait_lock);
 159         *prev_req = req->dl_next;
 160         write_unlock(&queue->syn_wait_lock);
 161 }
 162
 163 static inline void reqsk_queue_add(struct request_sock_queue *queue,
 164                                    struct request_sock *req,
 165                                    struct sock *parent,
 166                                    struct sock *child)
 167 {
 168         req->sk = child;
 169         sk_acceptq_added(parent);
 170
 171         if (queue->rskq_accept_head == NULL)
 172                 queue->rskq_accept_head = req;
 173         else
 174                 queue->rskq_accept_tail->dl_next = req;
 175
 176         queue->rskq_accept_tail = req;
 177         req->dl_next = NULL;
 178 }
 179
 180 static inline struct request_sock *reqsk_queue_remove(struct request_sock_queue *queue)
 181 {
 182         struct request_sock *req = queue->rskq_accept_head;
 183
 184         WARN_ON(req == NULL);
 185
 186         queue->rskq_accept_head = req->dl_next;
 187         if (queue->rskq_accept_head == NULL)
 188                 queue->rskq_accept_tail = NULL;
 189
 190         return req;
 191 }
 192
 193 static inline struct sock *reqsk_queue_get_child(struct request_sock_queue *queue,
 194                                                  struct sock *parent)
 195 {
 196         struct request_sock *req = reqsk_queue_remove(queue);
 197         struct sock *child = req->sk;
 198
 199         WARN_ON(child == NULL);
 200
 201         sk_acceptq_removed(parent);
 202         __reqsk_free(req);
 203         return child;
 204 }
 205
 206 static inline int reqsk_queue_removed(struct request_sock_queue *queue,
 207                                       struct request_sock *req)
 208 {
 209         struct listen_sock *lopt = queue->listen_opt;
 210
 211         if (req->retrans == 0)
 212                 --lopt->qlen_young;
 213
 214         return --lopt->qlen;
 215 }
 216
 217 static inline int reqsk_queue_added(struct request_sock_queue *queue)
 218 {
 219         struct listen_sock *lopt = queue->listen_opt;
 220         const int prev_qlen = lopt->qlen;
 221
 222         lopt->qlen_young++;
 223         lopt->qlen++;
 224         return prev_qlen;
 225 }
 226
 227 static inline int reqsk_queue_len(const struct request_sock_queue *queue)
 228 {
 229         return queue->listen_opt != NULL ? queue->listen_opt->qlen : 0;
 230 }
 231
 232 static inline int reqsk_queue_len_young(const struct request_sock_queue *queue)
 233 {
 234         return queue->listen_opt->qlen_young;
 235 }
 236
 237 static inline int reqsk_queue_is_full(const struct request_sock_queue *queue)
 238 {
 239         return queue->listen_opt->qlen >> queue->listen_opt->max_qlen_log;
 240 }
 241
 242 static inline void reqsk_queue_hash_req(struct request_sock_queue *queue,
 243                                         u32 hash, struct request_sock *req,
 244                                         unsigned long timeout)
 245 {
 246         struct listen_sock *lopt = queue->listen_opt;
 247
 248         req->expires = jiffies + timeout;
 249         req->retrans = 0;
 250         req->sk = NULL;
 251         req->dl_next = lopt->syn_table[hash];
 252
 253         write_lock(&queue->syn_wait_lock);
 254         lopt->syn_table[hash] = req;
 255         write_unlock(&queue->syn_wait_lock);
 256 }
 257
 258 #endif /* _REQUEST_SOCK_H */