/* * net/dccp/output.c * * An implementation of the DCCP protocol * Arnaldo Carvalho de Melo <acme@conectiva.com.br> * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version * 2 of the License, or (at your option) any later version. */ #include <linux/dccp.h> #include <linux/kernel.h> #include <linux/skbuff.h> #include <net/inet_sock.h> #include <net/sock.h> #include "ackvec.h" #include "ccid.h" #include "dccp.h" static inline void dccp_event_ack_sent(struct sock *sk) { inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK); } static void dccp_skb_entail(struct sock *sk, struct sk_buff *skb) { skb_set_owner_w(skb, sk); WARN_ON(sk->sk_send_head); sk->sk_send_head = skb; } /* * All SKB's seen here are completely headerless. It is our * job to build the DCCP header, and pass the packet down to * IP so it can do the same plus pass the packet off to the * device. */ static int dccp_transmit_skb(struct sock *sk, struct sk_buff *skb) { if (likely(skb != NULL)) { const struct inet_sock *inet = inet_sk(sk); const struct inet_connection_sock *icsk = inet_csk(sk); struct dccp_sock *dp = dccp_sk(sk); struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb); struct dccp_hdr *dh; /* XXX For now we're using only 48 bits sequence numbers */ const u32 dccp_header_size = sizeof(*dh) + sizeof(struct dccp_hdr_ext) + dccp_packet_hdr_len(dcb->dccpd_type); int err, set_ack = 1; u64 ackno = dp->dccps_gsr; /* * Increment GSS here already in case the option code needs it. * Update GSS for real only if option processing below succeeds. */ dcb->dccpd_seq = ADD48(dp->dccps_gss, 1); switch (dcb->dccpd_type) { case DCCP_PKT_DATA: set_ack = 0; /* fall through */ case DCCP_PKT_DATAACK: case DCCP_PKT_RESET: break; case DCCP_PKT_REQUEST: set_ack = 0; /* Use ISS on the first (non-retransmitted) Request. */ if (icsk->icsk_retransmits == 0) dcb->dccpd_seq = dp->dccps_iss; /* fall through */ case DCCP_PKT_SYNC: case DCCP_PKT_SYNCACK: ackno = dcb->dccpd_ack_seq; /* fall through */ default: /* * Set owner/destructor: some skbs are allocated via * alloc_skb (e.g. when retransmission may happen). * Only Data, DataAck, and Reset packets should come * through here with skb->sk set. */ WARN_ON(skb->sk); skb_set_owner_w(skb, sk); break; } if (dccp_insert_options(sk, skb)) { kfree_skb(skb); return -EPROTO; } /* Build DCCP header and checksum it. */ dh = dccp_zeroed_hdr(skb, dccp_header_size); dh->dccph_type = dcb->dccpd_type; dh->dccph_sport = inet->sport; dh->dccph_dport = inet->dport; dh->dccph_doff = (dccp_header_size + dcb->dccpd_opt_len) / 4; dh->dccph_ccval = dcb->dccpd_ccval; dh->dccph_cscov = dp->dccps_pcslen; /* XXX For now we're using only 48 bits sequence numbers */ dh->dccph_x = 1; dccp_update_gss(sk, dcb->dccpd_seq); dccp_hdr_set_seq(dh, dp->dccps_gss); if (set_ack) dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), ackno); switch (dcb->dccpd_type) { case DCCP_PKT_REQUEST: dccp_hdr_request(skb)->dccph_req_service = dp->dccps_service; /* * Limit Ack window to ISS <= P.ackno <= GSS, so that * only Responses to Requests we sent are considered. */ dp->dccps_awl = dp->dccps_iss; break; case DCCP_PKT_RESET: dccp_hdr_reset(skb)->dccph_reset_code = dcb->dccpd_reset_code; break; } icsk->icsk_af_ops->send_check(sk, 0, skb); if (set_ack) dccp_event_ack_sent(sk); DCCP_INC_STATS(DCCP_MIB_OUTSEGS); err = icsk->icsk_af_ops->queue_xmit(skb, 0); return net_xmit_eval(err); } return -ENOBUFS; } /** * dccp_determine_ccmps - Find out about CCID-specfic packet-size limits * We only consider the HC-sender CCID for setting the CCMPS (RFC 4340, 14.), * since the RX CCID is restricted to feedback packets (Acks), which are small * in comparison with the data traffic. A value of 0 means "no current CCMPS". */ static u32 dccp_determine_ccmps(const struct dccp_sock *dp) { const struct ccid *tx_ccid = dp->dccps_hc_tx_ccid; if (tx_ccid == NULL || tx_ccid->ccid_ops == NULL) return 0; return tx_ccid->ccid_ops->ccid_ccmps; } unsigned int dccp_sync_mss(struct sock *sk, u32 pmtu) { struct inet_connection_sock *icsk = inet_csk(sk); struct dccp_sock *dp = dccp_sk(sk); u32 ccmps = dccp_determine_ccmps(dp); int cur_mps = ccmps ? min(pmtu, ccmps) : pmtu; /* Account for header lengths and IPv4/v6 option overhead */ cur_mps -= (icsk->icsk_af_ops->net_header_len + icsk->icsk_ext_hdr_len + sizeof(struct dccp_hdr) + sizeof(struct dccp_hdr_ext)); /* * FIXME: this should come from the CCID infrastructure, where, say, * TFRC will say it wants TIMESTAMPS, ELAPSED time, etc, for now lets * put a rough estimate for NDP + TIMESTAMP + TIMESTAMP_ECHO + ELAPSED * TIME + TFRC_OPT_LOSS_EVENT_RATE + TFRC_OPT_RECEIVE_RATE + padding to * make it a multiple of 4 */ cur_mps -= ((5 + 6 + 10 + 6 + 6 + 6 + 3) / 4) * 4; /* And store cached results */ icsk->icsk_pmtu_cookie = pmtu; dp->dccps_mss_cache = cur_mps; return cur_mps; } EXPORT_SYMBOL_GPL(dccp_sync_mss); void dccp_write_space(struct sock *sk) { read_lock(&sk->sk_callback_lock); if (sk->sk_sleep && waitqueue_active(sk->sk_sleep)) wake_up_interruptible(sk->sk_sleep); /* Should agree with poll, otherwise some programs break */ if (sock_writeable(sk)) sk_wake_async(sk, SOCK_WAKE_SPACE, POLL_OUT); read_unlock(&sk->sk_callback_lock); } /** * dccp_wait_for_ccid - Wait for ccid to tell us we can send a packet * @sk: socket to wait for * @skb: current skb to pass on for waiting * @delay: sleep timeout in milliseconds (> 0) * This function is called by default when the socket is closed, and * when a non-zero linger time is set on the socket. For consistency */ static int dccp_wait_for_ccid(struct sock *sk, struct sk_buff *skb, int delay) { struct dccp_sock *dp = dccp_sk(sk); DEFINE_WAIT(wait); unsigned long jiffdelay; int rc; do { dccp_pr_debug("delayed send by %d msec\n", delay); jiffdelay = msecs_to_jiffies(delay); prepare_to_wait(sk->sk_sleep, &wait, TASK_INTERRUPTIBLE); sk->sk_write_pending++; release_sock(sk); schedule_timeout(jiffdelay); lock_sock(sk); sk->sk_write_pending--; if (sk->sk_err) goto do_error; if (signal_pending(current)) goto do_interrupted; rc = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb); } while ((delay = rc) > 0); out: finish_wait(sk->sk_sleep, &wait); return rc; do_error: rc = -EPIPE; goto out; do_interrupted: rc = -EINTR; goto out; } void dccp_write_xmit(struct sock *sk, int block) { struct dccp_sock *dp = dccp_sk(sk); struct sk_buff *skb; while ((skb = skb_peek(&sk->sk_write_queue))) { int err = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb); if (err > 0) { if (!block) { sk_reset_timer(sk, &dp->dccps_xmit_timer, msecs_to_jiffies(err)+jiffies); break; } else err = dccp_wait_for_ccid(sk, skb, err); if (err && err != -EINTR) DCCP_BUG("err=%d after dccp_wait_for_ccid", err); } skb_dequeue(&sk->sk_write_queue); if (err == 0) { struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb); const int len = skb->len; if (sk->sk_state == DCCP_PARTOPEN) { /* See 8.1.5. Handshake Completion */ inet_csk_schedule_ack(sk); inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, inet_csk(sk)->icsk_rto, DCCP_RTO_MAX); dcb->dccpd_type = DCCP_PKT_DATAACK; } else if (dccp_ack_pending(sk)) dcb->dccpd_type = DCCP_PKT_DATAACK; else dcb->dccpd_type = DCCP_PKT_DATA; err = dccp_transmit_skb(sk, skb); ccid_hc_tx_packet_sent(dp->dccps_hc_tx_ccid, sk, 0, len); if (err) DCCP_BUG("err=%d after ccid_hc_tx_packet_sent", err); } else { dccp_pr_debug("packet discarded due to err=%d\n", err); kfree_skb(skb); } } } /** * dccp_retransmit_skb - Retransmit Request, Close, or CloseReq packets * There are only four retransmittable packet types in DCCP: * - Request in client-REQUEST state (sec. 8.1.1), * - CloseReq in server-CLOSEREQ state (sec. 8.3), * - Close in node-CLOSING state (sec. 8.3), * - Acks in client-PARTOPEN state (sec. 8.1.5, handled by dccp_delack_timer()). * This function expects sk->sk_send_head to contain the original skb. */ int dccp_retransmit_skb(struct sock *sk) { WARN_ON(sk->sk_send_head == NULL); if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk) != 0) return -EHOSTUNREACH; /* Routing failure or similar. */ /* this count is used to distinguish original and retransmitted skb */ inet_csk(sk)->icsk_retransmits++; return dccp_transmit_skb(sk, skb_clone(sk->sk_send_head, GFP_ATOMIC)); } struct sk_buff *dccp_make_response(struct sock *sk, struct dst_entry *dst, struct request_sock *req) { struct dccp_hdr *dh; struct dccp_request_sock *dreq; const u32 dccp_header_size = sizeof(struct dccp_hdr) + sizeof(struct dccp_hdr_ext) + sizeof(struct dccp_hdr_response); struct sk_buff *skb = sock_wmalloc(sk, sk->sk_prot->max_header, 1, GFP_ATOMIC); if (skb == NULL) return NULL; /* Reserve space for headers. */ skb_reserve(skb, sk->sk_prot->max_header); skb->dst = dst_clone(dst); dreq = dccp_rsk(req); if (inet_rsk(req)->acked) /* increase ISS upon retransmission */ dccp_inc_seqno(&dreq->dreq_iss); DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_RESPONSE; DCCP_SKB_CB(skb)->dccpd_seq = dreq->dreq_iss; /* Resolve feature dependencies resulting from choice of CCID */ if (dccp_feat_server_ccid_dependencies(dreq)) goto response_failed; if (dccp_insert_options_rsk(dreq, skb)) goto response_failed; /* Build and checksum header */ dh = dccp_zeroed_hdr(skb, dccp_header_size); dh->dccph_sport = inet_rsk(req)->loc_port; dh->dccph_dport = inet_rsk(req)->rmt_port; dh->dccph_doff = (dccp_header_size + DCCP_SKB_CB(skb)->dccpd_opt_len) / 4; dh->dccph_type = DCCP_PKT_RESPONSE; dh->dccph_x = 1; dccp_hdr_set_seq(dh, dreq->dreq_iss); dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), dreq->dreq_isr); dccp_hdr_response(skb)->dccph_resp_service = dreq->dreq_service; dccp_csum_outgoing(skb); /* We use `acked' to remember that a Response was already sent. */ inet_rsk(req)->acked = 1; DCCP_INC_STATS(DCCP_MIB_OUTSEGS); return skb; response_failed: kfree_skb(skb); return NULL; } EXPORT_SYMBOL_GPL(dccp_make_response); /* answer offending packet in @rcv_skb with Reset from control socket @ctl */ struct sk_buff *dccp_ctl_make_reset(struct sock *sk, struct sk_buff *rcv_skb) { struct dccp_hdr *rxdh = dccp_hdr(rcv_skb), *dh; struct dccp_skb_cb *dcb = DCCP_SKB_CB(rcv_skb); const u32 dccp_hdr_reset_len = sizeof(struct dccp_hdr) + sizeof(struct dccp_hdr_ext) + sizeof(struct dccp_hdr_reset); struct dccp_hdr_reset *dhr; struct sk_buff *skb; skb = alloc_skb(sk->sk_prot->max_header, GFP_ATOMIC); if (skb == NULL) return NULL; skb_reserve(skb, sk->sk_prot->max_header); /* Swap the send and the receive. */ dh = dccp_zeroed_hdr(skb, dccp_hdr_reset_len); dh->dccph_type = DCCP_PKT_RESET; dh->dccph_sport = rxdh->dccph_dport; dh->dccph_dport = rxdh->dccph_sport; dh->dccph_doff = dccp_hdr_reset_len / 4; dh->dccph_x = 1; dhr = dccp_hdr_reset(skb); dhr->dccph_reset_code = dcb->dccpd_reset_code; switch (dcb->dccpd_reset_code) { case DCCP_RESET_CODE_PACKET_ERROR: dhr->dccph_reset_data[0] = rxdh->dccph_type; break; case DCCP_RESET_CODE_OPTION_ERROR: /* fall through */ case DCCP_RESET_CODE_MANDATORY_ERROR: memcpy(dhr->dccph_reset_data, dcb->dccpd_reset_data, 3); break; } /* * From RFC 4340, 8.3.1: * If P.ackno exists, set R.seqno := P.ackno + 1. * Else set R.seqno := 0. */ if (dcb->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ) dccp_hdr_set_seq(dh, ADD48(dcb->dccpd_ack_seq, 1)); dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), dcb->dccpd_seq); dccp_csum_outgoing(skb); return skb; } EXPORT_SYMBOL_GPL(dccp_ctl_make_reset); /* send Reset on established socket, to close or abort the connection */ int dccp_send_reset(struct sock *sk, enum dccp_reset_codes code) { struct sk_buff *skb; /* * FIXME: what if rebuild_header fails? * Should we be doing a rebuild_header here? */ int err = inet_csk(sk)->icsk_af_ops->rebuild_header(sk); if (err != 0) return err; skb = sock_wmalloc(sk, sk->sk_prot->max_header, 1, GFP_ATOMIC); if (skb == NULL) return -ENOBUFS; /* Reserve space for headers and prepare control bits. */ skb_reserve(skb, sk->sk_prot->max_header); DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_RESET; DCCP_SKB_CB(skb)->dccpd_reset_code = code; return dccp_transmit_skb(sk, skb); } /* * Do all connect socket setups that can be done AF independent. */ static inline void dccp_connect_init(struct sock *sk) { struct dccp_sock *dp = dccp_sk(sk); struct dst_entry *dst = __sk_dst_get(sk); struct inet_connection_sock *icsk = inet_csk(sk); sk->sk_err = 0; sock_reset_flag(sk, SOCK_DONE); dccp_sync_mss(sk, dst_mtu(dst)); /* Initialise GAR as per 8.5; AWL/AWH are set in dccp_transmit_skb() */ dp->dccps_gar = dp->dccps_iss; icsk->icsk_retransmits = 0; } int dccp_connect(struct sock *sk) { struct sk_buff *skb; struct inet_connection_sock *icsk = inet_csk(sk); /* do not connect if feature negotiation setup fails */ if (dccp_feat_finalise_settings(dccp_sk(sk))) return -EPROTO; dccp_connect_init(sk); skb = alloc_skb(sk->sk_prot->max_header, sk->sk_allocation); if (unlikely(skb == NULL)) return -ENOBUFS; /* Reserve space for headers. */ skb_reserve(skb, sk->sk_prot->max_header); DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_REQUEST; dccp_skb_entail(sk, skb); dccp_transmit_skb(sk, skb_clone(skb, GFP_KERNEL)); DCCP_INC_STATS(DCCP_MIB_ACTIVEOPENS); /* Timer for repeating the REQUEST until an answer. */ inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, icsk->icsk_rto, DCCP_RTO_MAX); return 0; } EXPORT_SYMBOL_GPL(dccp_connect); void dccp_send_ack(struct sock *sk) { /* If we have been reset, we may not send again. */ if (sk->sk_state != DCCP_CLOSED) { struct sk_buff *skb = alloc_skb(sk->sk_prot->max_header, GFP_ATOMIC); if (skb == NULL) { inet_csk_schedule_ack(sk); inet_csk(sk)->icsk_ack.ato = TCP_ATO_MIN; inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK, TCP_DELACK_MAX, DCCP_RTO_MAX); return; } /* Reserve space for headers */ skb_reserve(skb, sk->sk_prot->max_header); DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_ACK; dccp_transmit_skb(sk, skb); } } EXPORT_SYMBOL_GPL(dccp_send_ack); #if 0 /* FIXME: Is this still necessary (11.3) - currently nowhere used by DCCP. */ void dccp_send_delayed_ack(struct sock *sk) { struct inet_connection_sock *icsk = inet_csk(sk); /* * FIXME: tune this timer. elapsed time fixes the skew, so no problem * with using 2s, and active senders also piggyback the ACK into a * DATAACK packet, so this is really for quiescent senders. */ unsigned long timeout = jiffies + 2 * HZ; /* Use new timeout only if there wasn't a older one earlier. */ if (icsk->icsk_ack.pending & ICSK_ACK_TIMER) { /* If delack timer was blocked or is about to expire, * send ACK now. * * FIXME: check the "about to expire" part */ if (icsk->icsk_ack.blocked) { dccp_send_ack(sk); return; } if (!time_before(timeout, icsk->icsk_ack.timeout)) timeout = icsk->icsk_ack.timeout; } icsk->icsk_ack.pending |= ICSK_ACK_SCHED | ICSK_ACK_TIMER; icsk->icsk_ack.timeout = timeout; sk_reset_timer(sk, &icsk->icsk_delack_timer, timeout); } #endif void dccp_send_sync(struct sock *sk, const u64 ackno, const enum dccp_pkt_type pkt_type) { /* * We are not putting this on the write queue, so * dccp_transmit_skb() will set the ownership to this * sock. */ struct sk_buff *skb = alloc_skb(sk->sk_prot->max_header, GFP_ATOMIC); if (skb == NULL) { /* FIXME: how to make sure the sync is sent? */ DCCP_CRIT("could not send %s", dccp_packet_name(pkt_type)); return; } /* Reserve space for headers and prepare control bits. */ skb_reserve(skb, sk->sk_prot->max_header); DCCP_SKB_CB(skb)->dccpd_type = pkt_type; DCCP_SKB_CB(skb)->dccpd_ack_seq = ackno; dccp_transmit_skb(sk, skb); } EXPORT_SYMBOL_GPL(dccp_send_sync); /* * Send a DCCP_PKT_CLOSE/CLOSEREQ. The caller locks the socket for us. This * cannot be allowed to fail queueing a DCCP_PKT_CLOSE/CLOSEREQ frame under * any circumstances. */ void dccp_send_close(struct sock *sk, const int active) { struct dccp_sock *dp = dccp_sk(sk); struct sk_buff *skb; const gfp_t prio = active ? GFP_KERNEL : GFP_ATOMIC; skb = alloc_skb(sk->sk_prot->max_header, prio); if (skb == NULL) return; /* Reserve space for headers and prepare control bits. */ skb_reserve(skb, sk->sk_prot->max_header); if (dp->dccps_role == DCCP_ROLE_SERVER && !dp->dccps_server_timewait) DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_CLOSEREQ; else DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_CLOSE; if (active) { dccp_write_xmit(sk, 1); dccp_skb_entail(sk, skb); dccp_transmit_skb(sk, skb_clone(skb, prio)); /* * Retransmission timer for active-close: RFC 4340, 8.3 requires * to retransmit the Close/CloseReq until the CLOSING/CLOSEREQ * state can be left. The initial timeout is 2 RTTs. * Since RTT measurement is done by the CCIDs, there is no easy * way to get an RTT sample. The fallback RTT from RFC 4340, 3.4 * is too low (200ms); we use a high value to avoid unnecessary * retransmissions when the link RTT is > 0.2 seconds. * FIXME: Let main module sample RTTs and use that instead. */ inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, DCCP_TIMEOUT_INIT, DCCP_RTO_MAX); } else dccp_transmit_skb(sk, skb); }