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