Merge git://oak/home/sfr/kernels/iseries/work

[linux-2.6/mini2440.git] / net / dccp / output.c

/*
 *  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 "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);
}

/*
 * 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);

                if (!skb->sk)
                        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 =
                                                        dp->dccps_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);

                memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
                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) {
                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);
        } else
                kfree_skb(skb);

        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;
        struct dccp_request_sock *dreq;
        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;

        dreq = dccp_rsk(req);
        DCCP_SKB_CB(skb)->dccpd_type = DCCP_PKT_RESPONSE;
        DCCP_SKB_CB(skb)->dccpd_seq  = dreq->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, 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;

        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;
        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 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);
        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);
}