linux/include/net/request_sock.h
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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
  30/* empty to "strongly type" an otherwise void parameter.
  31 */
  32struct request_values {
  33};
  34
  35struct 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 */
  54struct 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
  70static 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
  80static inline void __reqsk_free(struct request_sock *req)
  81{
  82        kmem_cache_free(req->rsk_ops->slab, req);
  83}
  84
  85static inline void reqsk_free(struct request_sock *req)
  86{
  87        req->rsk_ops->destructor(req);
  88        __reqsk_free(req);
  89}
  90
  91extern 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 */
  97struct 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 */
 125struct 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
 134extern int reqsk_queue_alloc(struct request_sock_queue *queue,
 135                             unsigned int nr_table_entries);
 136
 137extern void __reqsk_queue_destroy(struct request_sock_queue *queue);
 138extern void reqsk_queue_destroy(struct request_sock_queue *queue);
 139
 140static 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
 149static inline int reqsk_queue_empty(struct request_sock_queue *queue)
 150{
 151        return queue->rskq_accept_head == NULL;
 152}
 153
 154static 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
 163static 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
 180static 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
 193static 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
 206static 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
 217static 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
 227static 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
 232static inline int reqsk_queue_len_young(const struct request_sock_queue *queue)
 233{
 234        return queue->listen_opt->qlen_young;
 235}
 236
 237static 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
 242static 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 */
 259
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