1 files changed, 528 insertions, 0 deletions

diff --git a/net/dccp/output.c b/net/dccp/output.c
new file mode 100644
index 0000000..28de157
--- /dev/null
+++ b/net/dccp/output.c
@@ -0,0 +1,528 @@
+/*
+ *  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/config.h>
+#include <linux/dccp.h>
+#include <linux/skbuff.h>
+
+#include <net/sock.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);
+}
+
+/*
+ * 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;
+
+		dccp_inc_seqno(&dp->dccps_gss);
+
+		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;
+		}
+
+		dcb->dccpd_seq = dp->dccps_gss;
+		dccp_insert_options(sk, skb);
+		
+		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, inet->saddr,
+						      inet->daddr);
+
+		if (set_ack)
+			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;
+}
+
+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, 2, 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
+ * @timeo: for how long
+ */
+static int dccp_wait_for_ccid(struct sock *sk, struct sk_buff *skb,
+			      long *timeo)
+{
+	struct dccp_sock *dp = dccp_sk(sk);
+	DEFINE_WAIT(wait);
+	long delay;
+	int rc;
+
+	while (1) {
+		prepare_to_wait(sk->sk_sleep, &wait, TASK_INTERRUPTIBLE);
+
+		if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN))
+			goto do_error;
+		if (!*timeo)
+			goto do_nonblock;
+		if (signal_pending(current))
+			goto do_interrupted;
+
+		rc = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb,
+					    skb->len);
+		if (rc <= 0)
+			break;
+		delay = msecs_to_jiffies(rc);
+		if (delay > *timeo || delay < 0)
+			goto do_nonblock;
+
+		sk->sk_write_pending++;
+		release_sock(sk);
+		*timeo -= schedule_timeout(delay);
+		lock_sock(sk);
+		sk->sk_write_pending--;
+	}
+out:
+	finish_wait(sk->sk_sleep, &wait);
+	return rc;
+
+do_error:
+	rc = -EPIPE;
+	goto out;
+do_nonblock:
+	rc = -EAGAIN;
+	goto out;
+do_interrupted:
+	rc = sock_intr_errno(*timeo);
+	goto out;
+}
+
+int dccp_write_xmit(struct sock *sk, struct sk_buff *skb, long *timeo)
+{
+	const struct dccp_sock *dp = dccp_sk(sk);
+	int err = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb,
+					 skb->len);
+
+	if (err > 0)
+		err = dccp_wait_for_ccid(sk, skb, timeo);
+
+	if (err == 0) {
+		const struct dccp_ackpkts *ap = dp->dccps_hc_rx_ackpkts;
+		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;
+			/*
+			 * FIXME: we really should have a
+			 * dccps_ack_pending or use icsk.
+			 */
+		} else if (inet_csk_ack_scheduled(sk) ||
+			   dp->dccps_timestamp_echo != 0 ||
+			   (dp->dccps_options.dccpo_send_ack_vector &&
+			    ap->dccpap_buf_ackno != DCCP_MAX_SEQNO + 1 &&
+			    ap->dccpap_ack_seqno == DCCP_MAX_SEQNO + 1))
+			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);
+	}
+
+	return err;
+}
+
+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, inet_rsk(req)->loc_addr,
+					      inet_rsk(req)->rmt_addr);
+
+	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, inet_sk(sk)->saddr,
+					      inet_sk(sk)->daddr);
+
+	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, DCCP_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,
+						  DCCP_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, const u64 seq,
+		    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(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 = pkt_type;
+	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, const int active)
+{
+	struct dccp_sock *dp = dccp_sk(sk);
+	struct sk_buff *skb;
+	const unsigned int 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);
+	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);
+	if (active) {
+		BUG_TRAP(sk->sk_send_head == NULL);
+		sk->sk_send_head = skb;
+		dccp_transmit_skb(sk, skb_clone(skb, prio));
+	} else
+		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);
+}