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 */ 250