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 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 */ 54 struct 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 70 static 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 80 static inline void __reqsk_free(struct request_sock *req) 81 { 82 kmem_cache_free(req->rsk_ops->slab, req); 83 } 84 85 static inline void reqsk_free(struct request_sock *req) 86 { 87 req->rsk_ops->destructor(req); 88 __reqsk_free(req); 89 } 90 91 extern 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 */ 97 struct 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 */ 125 struct 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 }; 133 134 extern int reqsk_queue_alloc(struct request_sock_queue *queue, 135 unsigned int nr_table_entries); 136 137 extern void __reqsk_queue_destroy(struct request_sock_queue *queue); 138 extern void reqsk_queue_destroy(struct request_sock_queue *queue); 139 140 static 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 } 148 149 static inline int reqsk_queue_empty(struct request_sock_queue *queue) 150 { 151 return queue->rskq_accept_head == NULL; 152 } 153 154 static 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 } 162 163 static 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 } 179 180 static 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 } 192 193 static 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 } 205 206 static 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 } 216 217 static 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 } 226 227 static inline int reqsk_queue_len(const struct request_sock_queue *queue) 228 { 229 return queue->listen_opt != NULL ? queue->listen_opt->qlen : 0; 230 } 231 232 static inline int reqsk_queue_len_young(const struct request_sock_queue *queue) 233 { 234 return queue->listen_opt->qlen_young; 235 } 236 237 static 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 } 241 242 static 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