From 7c657876b63cb1d8a2ec06f8fc6c37bb8412e66c Mon Sep 17 00:00:00 2001 From: Arnaldo Carvalho de Melo Date: Tue, 9 Aug 2005 20:14:34 -0700 Subject: [DCCP]: Initial implementation Development to this point was done on a subversion repository at: http://oops.ghostprotocols.net:81/cgi-bin/viewcvs.cgi/dccp-2.6/ This repository will be kept at this site for the foreseable future, so that interested parties can see the history of this code, attributions, etc. If I ever decide to take this offline I'll provide the full history at some other suitable place. Signed-off-by: Arnaldo Carvalho de Melo Signed-off-by: David S. Miller --- net/dccp/output.c | 406 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 406 insertions(+) create mode 100644 net/dccp/output.c (limited to 'net/dccp/output.c') diff --git a/net/dccp/output.c b/net/dccp/output.c new file mode 100644 index 00000000000..22ca2910d4f --- /dev/null +++ b/net/dccp/output.c @@ -0,0 +1,406 @@ +/* + * net/dccp/output.c + * + * An implementation of the DCCP protocol + * Arnaldo Carvalho de Melo + * + * 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 +#include +#include + +#include + +#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); +} + +/* + * 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. + */ +int dccp_transmit_skb(struct sock *sk, struct sk_buff *skb) +{ + if (likely(skb != NULL)) { + const struct inet_sock *inet = inet_sk(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 int 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; + + /* + * FIXME: study DCCP_PKT_SYNC[ACK] to see what is the right thing + * to do here... + */ + dccp_inc_seqno(&dp->dccps_gss); + + dcb->dccpd_seq = dp->dccps_gss; + dccp_insert_options(sk, skb); + + switch (dcb->dccpd_type) { + case DCCP_PKT_DATA: + set_ack = 0; + break; + case DCCP_PKT_SYNC: + case DCCP_PKT_SYNCACK: + ackno = dcb->dccpd_seq; + break; + } + + skb->h.raw = skb_push(skb, dccp_header_size); + dh = dccp_hdr(skb); + /* Data packets are not cloned as they are never retransmitted */ + if (skb_cloned(skb)) + skb_set_owner_w(skb, sk); + + /* Build DCCP header and checksum it. */ + memset(dh, 0, 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; + /* XXX For now we're using only 48 bits sequence numbers */ + dh->dccph_x = 1; + + dp->dccps_awh = dp->dccps_gss; + 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 = dcb->dccpd_service; + break; + case DCCP_PKT_RESET: + dccp_hdr_reset(skb)->dccph_reset_code = dcb->dccpd_reset_code; + break; + } + + dh->dccph_checksum = dccp_v4_checksum(skb); + + if (dcb->dccpd_type == DCCP_PKT_ACK || + dcb->dccpd_type == DCCP_PKT_DATAACK) + dccp_event_ack_sent(sk); + + DCCP_INC_STATS(DCCP_MIB_OUTSEGS); + + err = ip_queue_xmit(skb, 0); + if (err <= 0) + return err; + + /* NET_XMIT_CN is special. It does not guarantee, + * that this packet is lost. It tells that device + * is about to start to drop packets or already + * drops some packets of the same priority and + * invokes us to send less aggressively. + */ + return err == NET_XMIT_CN ? 0 : err; + } + return -ENOBUFS; +} + +unsigned int dccp_sync_mss(struct sock *sk, u32 pmtu) +{ + struct dccp_sock *dp = dccp_sk(sk); + int mss_now; + + /* + * FIXME: we really should be using the af_specific thing to support IPv6. + * mss_now = pmtu - tp->af_specific->net_header_len - sizeof(struct dccp_hdr) - sizeof(struct dccp_hdr_ext); + */ + mss_now = pmtu - sizeof(struct iphdr) - sizeof(struct dccp_hdr) - sizeof(struct dccp_hdr_ext); + + /* Now subtract optional transport overhead */ + mss_now -= dp->dccps_ext_header_len; + + /* + * 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 + */ + + mss_now -= ((5 + 6 + 10 + 6 + 6 + 6 + 3) / 4) * 4; + + /* And store cached results */ + dp->dccps_pmtu_cookie = pmtu; + dp->dccps_mss_cache = mss_now; + + return mss_now; +} + +int dccp_retransmit_skb(struct sock *sk, struct sk_buff *skb) +{ + if (inet_sk_rebuild_header(sk) != 0) + return -EHOSTUNREACH; /* Routing failure or similar. */ + + return dccp_transmit_skb(sk, (skb_cloned(skb) ? + pskb_copy(skb, GFP_ATOMIC): + skb_clone(skb, GFP_ATOMIC))); +} + +struct sk_buff *dccp_make_response(struct sock *sk, struct dst_entry *dst, + struct request_sock *req) +{ + struct dccp_hdr *dh; + const int dccp_header_size = sizeof(struct dccp_hdr) + + sizeof(struct dccp_hdr_ext) + + sizeof(struct dccp_hdr_response); + struct sk_buff *skb = sock_wmalloc(sk, MAX_HEADER + DCCP_MAX_OPT_LEN + + dccp_header_size, 1, + GFP_ATOMIC); + if (skb == NULL) + return NULL; + + /* Reserve space for headers. */ + skb_reserve(skb, MAX_HEADER + DCCP_MAX_OPT_LEN + dccp_header_size); + + skb->dst = dst_clone(dst); + skb->csum = 0; + + DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_RESPONSE; + DCCP_SKB_CB(skb)->dccpd_seq = dccp_rsk(req)->dreq_iss; + dccp_insert_options(sk, skb); + + skb->h.raw = skb_push(skb, dccp_header_size); + + dh = dccp_hdr(skb); + memset(dh, 0, dccp_header_size); + + dh->dccph_sport = inet_sk(sk)->sport; + 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, dccp_rsk(req)->dreq_iss); + dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), dccp_rsk(req)->dreq_isr); + + dh->dccph_checksum = dccp_v4_checksum(skb); + + DCCP_INC_STATS(DCCP_MIB_OUTSEGS); + return skb; +} + +struct sk_buff *dccp_make_reset(struct sock *sk, struct dst_entry *dst, + const enum dccp_reset_codes code) + +{ + struct dccp_hdr *dh; + struct dccp_sock *dp = dccp_sk(sk); + const int dccp_header_size = sizeof(struct dccp_hdr) + + sizeof(struct dccp_hdr_ext) + + sizeof(struct dccp_hdr_reset); + struct sk_buff *skb = sock_wmalloc(sk, MAX_HEADER + DCCP_MAX_OPT_LEN + + dccp_header_size, 1, + GFP_ATOMIC); + if (skb == NULL) + return NULL; + + /* Reserve space for headers. */ + skb_reserve(skb, MAX_HEADER + DCCP_MAX_OPT_LEN + dccp_header_size); + + skb->dst = dst_clone(dst); + skb->csum = 0; + + dccp_inc_seqno(&dp->dccps_gss); + + DCCP_SKB_CB(skb)->dccpd_reset_code = code; + DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_RESET; + DCCP_SKB_CB(skb)->dccpd_seq = dp->dccps_gss; + dccp_insert_options(sk, skb); + + skb->h.raw = skb_push(skb, dccp_header_size); + + dh = dccp_hdr(skb); + memset(dh, 0, dccp_header_size); + + dh->dccph_sport = inet_sk(sk)->sport; + dh->dccph_dport = inet_sk(sk)->dport; + dh->dccph_doff = (dccp_header_size + DCCP_SKB_CB(skb)->dccpd_opt_len) / 4; + dh->dccph_type = DCCP_PKT_RESET; + dh->dccph_x = 1; + dccp_hdr_set_seq(dh, dp->dccps_gss); + dccp_hdr_set_ack(dccp_hdr_ack_bits(skb), dp->dccps_gsr); + + dccp_hdr_reset(skb)->dccph_reset_code = code; + + dh->dccph_checksum = dccp_v4_checksum(skb); + + DCCP_INC_STATS(DCCP_MIB_OUTSEGS); + return skb; +} + +/* + * Do all connect socket setups that can be done AF independent. + */ +static inline void dccp_connect_init(struct sock *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)); + + /* + * FIXME: set dp->{dccps_swh,dccps_swl}, with + * something like dccp_inc_seq + */ + + icsk->icsk_retransmits = 0; +} + +int dccp_connect(struct sock *sk) +{ + struct sk_buff *skb; + struct inet_connection_sock *icsk = inet_csk(sk); + + dccp_connect_init(sk); + + skb = alloc_skb(MAX_DCCP_HEADER + 15, sk->sk_allocation); + if (unlikely(skb == NULL)) + return -ENOBUFS; + + /* Reserve space for headers. */ + skb_reserve(skb, MAX_DCCP_HEADER); + + DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_REQUEST; + /* FIXME: set service to something meaningful, coming + * from userspace*/ + DCCP_SKB_CB(skb)->dccpd_service = 0; + skb->csum = 0; + skb_set_owner_w(skb, sk); + + BUG_TRAP(sk->sk_send_head == NULL); + sk->sk_send_head = 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, TCP_RTO_MAX); + return 0; +} + +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(MAX_DCCP_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, TCP_RTO_MAX); + return; + } + + /* Reserve space for headers */ + skb_reserve(skb, MAX_DCCP_HEADER); + skb->csum = 0; + DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_ACK; + skb_set_owner_w(skb, sk); + dccp_transmit_skb(sk, skb); + } +} + +EXPORT_SYMBOL_GPL(dccp_send_ack); + +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); +} + +void dccp_send_sync(struct sock *sk, u64 seq) +{ + /* + * 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(MAX_DCCP_HEADER, GFP_ATOMIC); + + if (skb == NULL) + /* FIXME: how to make sure the sync is sent? */ + return; + + /* Reserve space for headers and prepare control bits. */ + skb_reserve(skb, MAX_DCCP_HEADER); + skb->csum = 0; + DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_SYNC; + DCCP_SKB_CB(skb)->dccpd_seq = seq; + + skb_set_owner_w(skb, sk); + dccp_transmit_skb(sk, skb); +} + +/* 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) +{ + struct dccp_sock *dp = dccp_sk(sk); + struct sk_buff *skb; + + /* Socket is locked, keep trying until memory is available. */ + for (;;) { + skb = alloc_skb(sk->sk_prot->max_header, GFP_KERNEL); + if (skb != NULL) + break; + yield(); + } + + /* Reserve space for headers and prepare control bits. */ + skb_reserve(skb, sk->sk_prot->max_header); + skb->csum = 0; + DCCP_SKB_CB(skb)->dccpd_type = dp->dccps_role == DCCP_ROLE_CLIENT ? DCCP_PKT_CLOSE : DCCP_PKT_CLOSEREQ; + + skb_set_owner_w(skb, sk); + dccp_transmit_skb(sk, skb); + + ccid_hc_rx_exit(dp->dccps_hc_rx_ccid, sk); + ccid_hc_tx_exit(dp->dccps_hc_tx_ccid, sk); +} -- cgit v1.2.3