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 int (*rtx_syn_ack)(struct sock *sk, 35 struct request_sock *req); 36 void (*send_ack)(struct sock *sk, struct sk_buff *skb, 37 struct request_sock *req); 38 void (*send_reset)(struct sock *sk, 39 struct sk_buff *skb); 40 void (*destructor)(struct request_sock *req); 41 }; 42 43 /* struct request_sock - mini sock to represent a connection request 44 */ 45 struct request_sock { 46 struct request_sock *dl_next; /* Must be first member! */ 47 u16 mss; 48 u8 retrans; 49 u8 cookie_ts; /* syncookie: encode tcpopts in timestamp */ 50 /* The following two fields can be easily recomputed I think -AK */ 51 u32 window_clamp; /* window clamp at creation time */ 52 u32 rcv_wnd; /* rcv_wnd offered first time */ 53 u32 ts_recent; 54 unsigned long expires; 55 const struct request_sock_ops *rsk_ops; 56 struct sock *sk; 57 u32 secid; 58 u32 peer_secid; 59 }; 60 61 static inline struct request_sock *reqsk_alloc(const struct request_sock_ops *ops) 62 { 63 struct request_sock *req = kmem_cache_alloc(ops->slab, GFP_ATOMIC); 64 65 if (req != NULL) 66 req->rsk_ops = ops; 67 68 return req; 69 } 70 71 static inline void __reqsk_free(struct request_sock *req) 72 { 73 kmem_cache_free(req->rsk_ops->slab, req); 74 } 75 76 static inline void reqsk_free(struct request_sock *req) 77 { 78 req->rsk_ops->destructor(req); 79 __reqsk_free(req); 80 } 81 82 extern int sysctl_max_syn_backlog; 83 84 /** struct listen_sock - listen state 85 * 86 * @max_qlen_log - log_2 of maximal queued SYNs/REQUESTs 87 */ 88 struct listen_sock { 89 u8 max_qlen_log; 90 /* 3 bytes hole, try to use */ 91 int qlen; 92 int qlen_young; 93 int clock_hand; 94 u32 hash_rnd; 95 u32 nr_table_entries; 96 struct request_sock *syn_table[0]; 97 }; 98 99 /** struct request_sock_queue - queue of request_socks 100 * 101 * @rskq_accept_head - FIFO head of established children 102 * @rskq_accept_tail - FIFO tail of established children 103 * @rskq_defer_accept - User waits for some data after accept() 104 * @syn_wait_lock - serializer 105 * 106 * %syn_wait_lock is necessary only to avoid proc interface having to grab the main 107 * lock sock while browsing the listening hash (otherwise it's deadlock prone). 108 * 109 * This lock is acquired in read mode only from listening_get_next() seq_file 110 * op and it's acquired in write mode _only_ from code that is actively 111 * changing rskq_accept_head. All readers that are holding the master sock lock 112 * don't need to grab this lock in read mode too as rskq_accept_head. writes 113 * are always protected from the main sock lock. 114 */ 115 struct request_sock_queue { 116 struct request_sock *rskq_accept_head; 117 struct request_sock *rskq_accept_tail; 118 rwlock_t syn_wait_lock; 119 u8 rskq_defer_accept; 120 /* 3 bytes hole, try to pack */ 121 struct listen_sock *listen_opt; 122 }; 123 124 extern int reqsk_queue_alloc(struct request_sock_queue *queue, 125 unsigned int nr_table_entries); 126 127 extern void __reqsk_queue_destroy(struct request_sock_queue *queue); 128 extern void reqsk_queue_destroy(struct request_sock_queue *queue); 129 130 static inline struct request_sock * 131 reqsk_queue_yank_acceptq(struct request_sock_queue *queue) 132 { 133 struct request_sock *req = queue->rskq_accept_head; 134 135 queue->rskq_accept_head = NULL; 136 return req; 137 } 138 139 static inline int reqsk_queue_empty(struct request_sock_queue *queue) 140 { 141 return queue->rskq_accept_head == NULL; 142 } 143 144 static inline void reqsk_queue_unlink(struct request_sock_queue *queue, 145 struct request_sock *req, 146 struct request_sock **prev_req) 147 { 148 write_lock(&queue->syn_wait_lock); 149 *prev_req = req->dl_next; 150 write_unlock(&queue->syn_wait_lock); 151 } 152 153 static inline void reqsk_queue_add(struct request_sock_queue *queue, 154 struct request_sock *req, 155 struct sock *parent, 156 struct sock *child) 157 { 158 req->sk = child; 159 sk_acceptq_added(parent); 160 161 if (queue->rskq_accept_head == NULL) 162 queue->rskq_accept_head = req; 163 else 164 queue->rskq_accept_tail->dl_next = req; 165 166 queue->rskq_accept_tail = req; 167 req->dl_next = NULL; 168 } 169 170 static inline struct request_sock *reqsk_queue_remove(struct request_sock_queue *queue) 171 { 172 struct request_sock *req = queue->rskq_accept_head; 173 174 WARN_ON(req == NULL); 175 176 queue->rskq_accept_head = req->dl_next; 177 if (queue->rskq_accept_head == NULL) 178 queue->rskq_accept_tail = NULL; 179 180 return req; 181 } 182 183 static inline struct sock *reqsk_queue_get_child(struct request_sock_queue *queue, 184 struct sock *parent) 185 { 186 struct request_sock *req = reqsk_queue_remove(queue); 187 struct sock *child = req->sk; 188 189 WARN_ON(child == NULL); 190 191 sk_acceptq_removed(parent); 192 __reqsk_free(req); 193 return child; 194 } 195 196 static inline int reqsk_queue_removed(struct request_sock_queue *queue, 197 struct request_sock *req) 198 { 199 struct listen_sock *lopt = queue->listen_opt; 200 201 if (req->retrans == 0) 202 --lopt->qlen_young; 203 204 return --lopt->qlen; 205 } 206 207 static inline int reqsk_queue_added(struct request_sock_queue *queue) 208 { 209 struct listen_sock *lopt = queue->listen_opt; 210 const int prev_qlen = lopt->qlen; 211 212 lopt->qlen_young++; 213 lopt->qlen++; 214 return prev_qlen; 215 } 216 217 static inline int reqsk_queue_len(const struct request_sock_queue *queue) 218 { 219 return queue->listen_opt != NULL ? queue->listen_opt->qlen : 0; 220 } 221 222 static inline int reqsk_queue_len_young(const struct request_sock_queue *queue) 223 { 224 return queue->listen_opt->qlen_young; 225 } 226 227 static inline int reqsk_queue_is_full(const struct request_sock_queue *queue) 228 { 229 return queue->listen_opt->qlen >> queue->listen_opt->max_qlen_log; 230 } 231 232 static inline void reqsk_queue_hash_req(struct request_sock_queue *queue, 233 u32 hash, struct request_sock *req, 234 unsigned long timeout) 235 { 236 struct listen_sock *lopt = queue->listen_opt; 237 238 req->expires = jiffies + timeout; 239 req->retrans = 0; 240 req->sk = NULL; 241 req->dl_next = lopt->syn_table[hash]; 242 243 write_lock(&queue->syn_wait_lock); 244 lopt->syn_table[hash] = req; 245 write_unlock(&queue->syn_wait_lock); 246 } 247 248 #endif /* _REQUEST_SOCK_H */ 249