4 * An implementation of the DCCP protocol
5 * Arnaldo Carvalho de Melo <acme@conectiva.com.br>
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License
9 * as published by the Free Software Foundation; either version
10 * 2 of the License, or (at your option) any later version.
13 #include <linux/dccp.h>
14 #include <linux/gfp.h>
15 #include <linux/kernel.h>
16 #include <linux/skbuff.h>
17 #include <linux/timer.h>
21 #include <net/inet_timewait_sock.h>
28 struct inet_timewait_death_row dccp_death_row = {
29 .sysctl_max_tw_buckets = NR_FILE * 2,
30 .hashinfo = &dccp_hashinfo,
33 EXPORT_SYMBOL_GPL(dccp_death_row);
35 void dccp_time_wait(struct sock *sk, int state, int timeo)
37 struct inet_timewait_sock *tw;
39 tw = inet_twsk_alloc(sk, &dccp_death_row, state);
42 const struct inet_connection_sock *icsk = inet_csk(sk);
43 const int rto = (icsk->icsk_rto << 2) - (icsk->icsk_rto >> 1);
44 #if IS_ENABLED(CONFIG_IPV6)
45 if (tw->tw_family == PF_INET6) {
46 tw->tw_v6_daddr = sk->sk_v6_daddr;
47 tw->tw_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
48 tw->tw_ipv6only = sk->sk_ipv6only;
52 /* Get the TIME_WAIT timeout firing. */
56 tw->tw_timeout = DCCP_TIMEWAIT_LEN;
57 if (state == DCCP_TIME_WAIT)
58 timeo = DCCP_TIMEWAIT_LEN;
60 /* tw_timer is pinned, so we need to make sure BH are disabled
61 * in following section, otherwise timer handler could run before
62 * we complete the initialization.
65 inet_twsk_schedule(tw, timeo);
66 /* Linkage updates. */
67 __inet_twsk_hashdance(tw, sk, &dccp_hashinfo);
71 /* Sorry, if we're out of memory, just CLOSE this
72 * socket up. We've got bigger problems than
73 * non-graceful socket closings.
75 DCCP_WARN("time wait bucket table overflow\n");
81 struct sock *dccp_create_openreq_child(const struct sock *sk,
82 const struct request_sock *req,
83 const struct sk_buff *skb)
86 * Step 3: Process LISTEN state
88 * (* Generate a new socket and switch to that socket *)
89 * Set S := new socket for this port pair
91 struct sock *newsk = inet_csk_clone_lock(sk, req, GFP_ATOMIC);
94 struct dccp_request_sock *dreq = dccp_rsk(req);
95 struct inet_connection_sock *newicsk = inet_csk(newsk);
96 struct dccp_sock *newdp = dccp_sk(newsk);
98 newdp->dccps_role = DCCP_ROLE_SERVER;
99 newdp->dccps_hc_rx_ackvec = NULL;
100 newdp->dccps_service_list = NULL;
101 newdp->dccps_hc_rx_ccid = NULL;
102 newdp->dccps_hc_tx_ccid = NULL;
103 newdp->dccps_service = dreq->dreq_service;
104 newdp->dccps_timestamp_echo = dreq->dreq_timestamp_echo;
105 newdp->dccps_timestamp_time = dreq->dreq_timestamp_time;
106 newicsk->icsk_rto = DCCP_TIMEOUT_INIT;
108 INIT_LIST_HEAD(&newdp->dccps_featneg);
110 * Step 3: Process LISTEN state
112 * Choose S.ISS (initial seqno) or set from Init Cookies
113 * Initialize S.GAR := S.ISS
114 * Set S.ISR, S.GSR from packet (or Init Cookies)
116 * Setting AWL/AWH and SWL/SWH happens as part of the feature
117 * activation below, as these windows all depend on the local
118 * and remote Sequence Window feature values (7.5.2).
120 newdp->dccps_iss = dreq->dreq_iss;
121 newdp->dccps_gss = dreq->dreq_gss;
122 newdp->dccps_gar = newdp->dccps_iss;
123 newdp->dccps_isr = dreq->dreq_isr;
124 newdp->dccps_gsr = dreq->dreq_gsr;
127 * Activate features: initialise CCIDs, sequence windows etc.
129 if (dccp_feat_activate_values(newsk, &dreq->dreq_featneg)) {
130 /* It is still raw copy of parent, so invalidate
131 * destructor and make plain sk_free() */
132 newsk->sk_destruct = NULL;
133 bh_unlock_sock(newsk);
137 dccp_init_xmit_timers(newsk);
139 __DCCP_INC_STATS(DCCP_MIB_PASSIVEOPENS);
144 EXPORT_SYMBOL_GPL(dccp_create_openreq_child);
147 * Process an incoming packet for RESPOND sockets represented
148 * as an request_sock.
150 struct sock *dccp_check_req(struct sock *sk, struct sk_buff *skb,
151 struct request_sock *req)
153 struct sock *child = NULL;
154 struct dccp_request_sock *dreq = dccp_rsk(req);
157 /* TCP/DCCP listeners became lockless.
158 * DCCP stores complex state in its request_sock, so we need
159 * a protection for them, now this code runs without being protected
160 * by the parent (listener) lock.
162 spin_lock_bh(&dreq->dreq_lock);
164 /* Check for retransmitted REQUEST */
165 if (dccp_hdr(skb)->dccph_type == DCCP_PKT_REQUEST) {
167 if (after48(DCCP_SKB_CB(skb)->dccpd_seq, dreq->dreq_gsr)) {
168 dccp_pr_debug("Retransmitted REQUEST\n");
169 dreq->dreq_gsr = DCCP_SKB_CB(skb)->dccpd_seq;
171 * Send another RESPONSE packet
172 * To protect against Request floods, increment retrans
173 * counter (backoff, monitored by dccp_response_timer).
175 inet_rtx_syn_ack(sk, req);
177 /* Network Duplicate, discard packet */
181 DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR;
183 if (dccp_hdr(skb)->dccph_type != DCCP_PKT_ACK &&
184 dccp_hdr(skb)->dccph_type != DCCP_PKT_DATAACK)
188 if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
189 dreq->dreq_iss, dreq->dreq_gss)) {
190 dccp_pr_debug("Invalid ACK number: ack_seq=%llu, "
191 "dreq_iss=%llu, dreq_gss=%llu\n",
193 DCCP_SKB_CB(skb)->dccpd_ack_seq,
194 (unsigned long long) dreq->dreq_iss,
195 (unsigned long long) dreq->dreq_gss);
199 if (dccp_parse_options(sk, dreq, skb))
202 child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, req, NULL,
205 child = inet_csk_complete_hashdance(sk, child, req, own_req);
209 DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
211 if (dccp_hdr(skb)->dccph_type != DCCP_PKT_RESET)
212 req->rsk_ops->send_reset(sk, skb);
214 inet_csk_reqsk_queue_drop(sk, req);
216 spin_unlock_bh(&dreq->dreq_lock);
220 EXPORT_SYMBOL_GPL(dccp_check_req);
223 * Queue segment on the new socket if the new socket is active,
224 * otherwise we just shortcircuit this and continue with
227 int dccp_child_process(struct sock *parent, struct sock *child,
231 const int state = child->sk_state;
233 if (!sock_owned_by_user(child)) {
234 ret = dccp_rcv_state_process(child, skb, dccp_hdr(skb),
237 /* Wakeup parent, send SIGIO */
238 if (state == DCCP_RESPOND && child->sk_state != state)
239 parent->sk_data_ready(parent);
241 /* Alas, it is possible again, because we do lookup
242 * in main socket hash table and lock on listening
243 * socket does not protect us more.
245 __sk_add_backlog(child, skb);
248 bh_unlock_sock(child);
253 EXPORT_SYMBOL_GPL(dccp_child_process);
255 void dccp_reqsk_send_ack(const struct sock *sk, struct sk_buff *skb,
256 struct request_sock *rsk)
258 DCCP_BUG("DCCP-ACK packets are never sent in LISTEN/RESPOND state");
261 EXPORT_SYMBOL_GPL(dccp_reqsk_send_ack);
263 int dccp_reqsk_init(struct request_sock *req,
264 struct dccp_sock const *dp, struct sk_buff const *skb)
266 struct dccp_request_sock *dreq = dccp_rsk(req);
268 spin_lock_init(&dreq->dreq_lock);
269 inet_rsk(req)->ir_rmt_port = dccp_hdr(skb)->dccph_sport;
270 inet_rsk(req)->ir_num = ntohs(dccp_hdr(skb)->dccph_dport);
271 inet_rsk(req)->acked = 0;
272 dreq->dreq_timestamp_echo = 0;
274 /* inherit feature negotiation options from listening socket */
275 return dccp_feat_clone_list(&dp->dccps_featneg, &dreq->dreq_featneg);
278 EXPORT_SYMBOL_GPL(dccp_reqsk_init);