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 22 #include <net/sock.h> 23 24 struct request_sock; 25 struct sk_buff; 26 struct dst_entry; 27 struct proto; 28 29 struct request_sock_ops { 30 int family; 31 int obj_size; 32 struct kmem_cache *slab; 33 int (*rtx_syn_ack)(struct sock *sk, 34 struct request_sock *req); 35 void (*send_ack)(struct sk_buff *skb, 36 struct request_sock *req); 37 void (*send_reset)(struct sock *sk, 38 struct sk_buff *skb); 39 void (*destructor)(struct request_sock *req); 40 }; 41 42 /* struct request_sock - mini sock to represent a connection request 43 */ 44 struct request_sock { 45 struct request_sock *dl_next; /* Must be first member! */ 46 u16 mss; 47 u8 retrans; 48 u8 cookie_ts; /* syncookie: encode tcpopts in timestamp */ 49 /* The following two fields can be easily recomputed I think -AK */ 50 u32 window_clamp; /* window clamp at creation time */ 51 u32 rcv_wnd; /* rcv_wnd offered first time */ 52 u32 ts_recent; 53 unsigned long expires; 54 const struct request_sock_ops *rsk_ops; 55 struct sock *sk; 56 u32 secid; 57 u32 peer_secid; 58 }; 59 60 static inline struct request_sock *reqsk_alloc(const struct request_sock_ops *ops) 61 { 62 struct request_sock *req = kmem_cache_alloc(ops->slab, GFP_ATOMIC); 63 64 if (req != NULL) 65 req->rsk_ops = ops; 66 67 return req; 68 } 69 70 static inline void __reqsk_free(struct request_sock *req) 71 { 72 kmem_cache_free(req->rsk_ops->slab, req); 73 } 74 75 static inline void reqsk_free(struct request_sock *req) 76 { 77 req->rsk_ops->destructor(req); 78 __reqsk_free(req); 79 } 80 81 extern int sysctl_max_syn_backlog; 82 83 /** struct listen_sock - listen state 84 * 85 * @max_qlen_log - log_2 of maximal queued SYNs/REQUESTs 86 */ 87 struct listen_sock { 88 u8 max_qlen_log; 89 /* 3 bytes hole, try to use */ 90 int qlen; 91 int qlen_young; 92 int clock_hand; 93 u32 hash_rnd; 94 u32 nr_table_entries; 95 struct request_sock *syn_table[0]; 96 }; 97 98 /** struct request_sock_queue - queue of request_socks 99 * 100 * @rskq_accept_head - FIFO head of established children 101 * @rskq_accept_tail - FIFO tail of established children 102 * @rskq_defer_accept - User waits for some data after accept() 103 * @syn_wait_lock - serializer 104 * 105 * %syn_wait_lock is necessary only to avoid proc interface having to grab the main 106 * lock sock while browsing the listening hash (otherwise it's deadlock prone). 107 * 108 * This lock is acquired in read mode only from listening_get_next() seq_file 109 * op and it's acquired in write mode _only_ from code that is actively 110 * changing rskq_accept_head. All readers that are holding the master sock lock 111 * don't need to grab this lock in read mode too as rskq_accept_head. writes 112 * are always protected from the main sock lock. 113 */ 114 struct request_sock_queue { 115 struct request_sock *rskq_accept_head; 116 struct request_sock *rskq_accept_tail; 117 rwlock_t syn_wait_lock; 118 u16 rskq_defer_accept; 119 /* 2 bytes hole, try to pack */ 120 struct listen_sock *listen_opt; 121 }; 122 123 extern int reqsk_queue_alloc(struct request_sock_queue *queue, 124 unsigned int nr_table_entries); 125 126 extern void __reqsk_queue_destroy(struct request_sock_queue *queue); 127 extern void reqsk_queue_destroy(struct request_sock_queue *queue); 128 129 static inline struct request_sock * 130 reqsk_queue_yank_acceptq(struct request_sock_queue *queue) 131 { 132 struct request_sock *req = queue->rskq_accept_head; 133 134 queue->rskq_accept_head = NULL; 135 return req; 136 } 137 138 static inline int reqsk_queue_empty(struct request_sock_queue *queue) 139 { 140 return queue->rskq_accept_head == NULL; 141 } 142 143 static inline void reqsk_queue_unlink(struct request_sock_queue *queue, 144 struct request_sock *req, 145 struct request_sock **prev_req) 146 { 147 write_lock(&queue->syn_wait_lock); 148 *prev_req = req->dl_next; 149 write_unlock(&queue->syn_wait_lock); 150 } 151 152 static inline void reqsk_queue_add(struct request_sock_queue *queue, 153 struct request_sock *req, 154 struct sock *parent, 155 struct sock *child) 156 { 157 req->sk = child; 158 sk_acceptq_added(parent); 159 160 if (queue->rskq_accept_head == NULL) 161 queue->rskq_accept_head = req; 162 else 163 queue->rskq_accept_tail->dl_next = req; 164 165 queue->rskq_accept_tail = req; 166 req->dl_next = NULL; 167 } 168 169 static inline struct request_sock *reqsk_queue_remove(struct request_sock_queue *queue) 170 { 171 struct request_sock *req = queue->rskq_accept_head; 172 173 BUG_TRAP(req != NULL); 174 175 queue->rskq_accept_head = req->dl_next; 176 if (queue->rskq_accept_head == NULL) 177 queue->rskq_accept_tail = NULL; 178 179 return req; 180 } 181 182 static inline struct sock *reqsk_queue_get_child(struct request_sock_queue *queue, 183 struct sock *parent) 184 { 185 struct request_sock *req = reqsk_queue_remove(queue); 186 struct sock *child = req->sk; 187 188 BUG_TRAP(child != NULL); 189 190 sk_acceptq_removed(parent); 191 __reqsk_free(req); 192 return child; 193 } 194 195 static inline int reqsk_queue_removed(struct request_sock_queue *queue, 196 struct request_sock *req) 197 { 198 struct listen_sock *lopt = queue->listen_opt; 199 200 if (req->retrans == 0) 201 --lopt->qlen_young; 202 203 return --lopt->qlen; 204 } 205 206 static inline int reqsk_queue_added(struct request_sock_queue *queue) 207 { 208 struct listen_sock *lopt = queue->listen_opt; 209 const int prev_qlen = lopt->qlen; 210 211 lopt->qlen_young++; 212 lopt->qlen++; 213 return prev_qlen; 214 } 215 216 static inline int reqsk_queue_len(const struct request_sock_queue *queue) 217 { 218 return queue->listen_opt != NULL ? queue->listen_opt->qlen : 0; 219 } 220 221 static inline int reqsk_queue_len_young(const struct request_sock_queue *queue) 222 { 223 return queue->listen_opt->qlen_young; 224 } 225 226 static inline int reqsk_queue_is_full(const struct request_sock_queue *queue) 227 { 228 return queue->listen_opt->qlen >> queue->listen_opt->max_qlen_log; 229 } 230 231 static inline void reqsk_queue_hash_req(struct request_sock_queue *queue, 232 u32 hash, struct request_sock *req, 233 unsigned long timeout) 234 { 235 struct listen_sock *lopt = queue->listen_opt; 236 237 req->expires = jiffies + timeout; 238 req->retrans = 0; 239 req->sk = NULL; 240 req->dl_next = lopt->syn_table[hash]; 241 242 write_lock(&queue->syn_wait_lock); 243 lopt->syn_table[hash] = req; 244 write_unlock(&queue->syn_wait_lock); 245 } 246 247 #endif /* _REQUEST_SOCK_H */ 248