dn_nsp_out.c

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/*
 * DECnet       An implementation of the DECnet protocol suite for the LINUX
 *              operating system.  DECnet is implemented using the  BSD Socket
 *              interface as the means of communication with the user level.
 *
 *              DECnet Network Services Protocol (Output)
 *
 * Author:      Eduardo Marcelo Serrat <[email protected]>
 *
 * Changes:
 *
 *    Steve Whitehouse:  Split into dn_nsp_in.c and dn_nsp_out.c from
 *                       original dn_nsp.c.
 *    Steve Whitehouse:  Updated to work with my new routing architecture.
 *    Steve Whitehouse:  Added changes from Eduardo Serrat's patches.
 *    Steve Whitehouse:  Now conninits have the "return" bit set.
 *    Steve Whitehouse:  Fixes to check alloc'd skbs are non NULL!
 *                       Moved output state machine into one function
 *    Steve Whitehouse:  New output state machine
 *         Paul Koning:  Connect Confirm message fix.
 *      Eduardo Serrat:  Fix to stop dn_nsp_do_disc() sending malformed packets.
 *    Steve Whitehouse:  dn_nsp_output() and friends needed a spring clean
 *    Steve Whitehouse:  Moved dn_nsp_send() in here from route.h
 */

/******************************************************************************
    (c) 1995-1998 E.M. Serrat       [email protected]

    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
    any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.
*******************************************************************************/

#include <linux/errno.h>
#include <linux/types.h>
#include <linux/socket.h>
#include <linux/in.h>
#include <linux/kernel.h>
#include <linux/timer.h>
#include <linux/string.h>
#include <linux/sockios.h>
#include <linux/net.h>
#include <linux/netdevice.h>
#include <linux/inet.h>
#include <linux/route.h>
#include <linux/slab.h>
#include <net/sock.h>
#include <linux/fcntl.h>
#include <linux/mm.h>
#include <linux/termios.h>
#include <linux/interrupt.h>
#include <linux/proc_fs.h>
#include <linux/stat.h>
#include <linux/init.h>
#include <linux/poll.h>
#include <linux/if_packet.h>
#include <net/neighbour.h>
#include <net/dst.h>
#include <net/flow.h>
#include <net/dn.h>
#include <net/dn_nsp.h>
#include <net/dn_dev.h>
#include <net/dn_route.h>


static int nsp_backoff[NSP_MAXRXTSHIFT + 1] = { 1, 2, 4, 8, 16, 32, 64, 64, 64, 64, 64, 64, 64 };

static void dn_nsp_send(struct sk_buff *skb)
{
    struct sock *sk = skb->sk;
    struct dn_scp *scp = DN_SK(sk);
    struct dst_entry *dst;
    struct flowidn fld;

    skb_reset_transport_header(skb);
    scp->stamp = jiffies;

    dst = sk_dst_check(sk, 0);
    if (dst) {
try_again:
        skb_dst_set(skb, dst);
        dst_output(skb);
        return;
    }

    memset(&fld, 0, sizeof(fld));
    fld.flowidn_oif = sk->sk_bound_dev_if;
    fld.saddr = dn_saddr2dn(&scp->addr);
    fld.daddr = dn_saddr2dn(&scp->peer);
    dn_sk_ports_copy(&fld, scp);
    fld.flowidn_proto = DNPROTO_NSP;
    if (dn_route_output_sock(&sk->sk_dst_cache, &fld, sk, 0) == 0) {
        dst = sk_dst_get(sk);
        sk->sk_route_caps = dst->dev->features;
        goto try_again;
    }

    sk->sk_err = EHOSTUNREACH;
    if (!sock_flag(sk, SOCK_DEAD))
        sk->sk_state_change(sk);
}


/*
 * If sk == NULL, then we assume that we are supposed to be making
 * a routing layer skb. If sk != NULL, then we are supposed to be
 * creating an skb for the NSP layer.
 *
 * The eventual aim is for each socket to have a cached header size
 * for its outgoing packets, and to set hdr from this when sk != NULL.
 */
struct sk_buff *dn_alloc_skb(struct sock *sk, int size, gfp_t pri)
{
    struct sk_buff *skb;
    int hdr = 64;

    if ((skb = alloc_skb(size + hdr, pri)) == NULL)
        return NULL;

    skb->protocol = htons(ETH_P_DNA_RT);
    skb->pkt_type = PACKET_OUTGOING;

    if (sk)
        skb_set_owner_w(skb, sk);

    skb_reserve(skb, hdr);

    return skb;
}

/*
 * Calculate persist timer based upon the smoothed round
 * trip time and the variance. Backoff according to the
 * nsp_backoff[] array.
 */
unsigned long dn_nsp_persist(struct sock *sk)
{
    struct dn_scp *scp = DN_SK(sk);

    unsigned long t = ((scp->nsp_srtt >> 2) + scp->nsp_rttvar) >> 1;

    t *= nsp_backoff[scp->nsp_rxtshift];

    if (t < HZ) t = HZ;
    if (t > (600*HZ)) t = (600*HZ);

    if (scp->nsp_rxtshift < NSP_MAXRXTSHIFT)
        scp->nsp_rxtshift++;

    /* printk(KERN_DEBUG "rxtshift %lu, t=%lu\n", scp->nsp_rxtshift, t); */

    return t;
}

/*
 * This is called each time we get an estimate for the rtt
 * on the link.
 */
static void dn_nsp_rtt(struct sock *sk, long rtt)
{
    struct dn_scp *scp = DN_SK(sk);
    long srtt = (long)scp->nsp_srtt;
    long rttvar = (long)scp->nsp_rttvar;
    long delta;

    /*
     * If the jiffies clock flips over in the middle of timestamp
     * gathering this value might turn out negative, so we make sure
     * that is it always positive here.
     */
    if (rtt < 0)
        rtt = -rtt;
    /*
     * Add new rtt to smoothed average
     */
    delta = ((rtt << 3) - srtt);
    srtt += (delta >> 3);
    if (srtt >= 1)
        scp->nsp_srtt = (unsigned long)srtt;
    else
        scp->nsp_srtt = 1;

    /*
     * Add new rtt varience to smoothed varience
     */
    delta >>= 1;
    rttvar += ((((delta>0)?(delta):(-delta)) - rttvar) >> 2);
    if (rttvar >= 1)
        scp->nsp_rttvar = (unsigned long)rttvar;
    else
        scp->nsp_rttvar = 1;

    /* printk(KERN_DEBUG "srtt=%lu rttvar=%lu\n", scp->nsp_srtt, scp->nsp_rttvar); */
}

static inline unsigned int dn_nsp_clone_and_send(struct sk_buff *skb,
                         gfp_t gfp)
{
    struct dn_skb_cb *cb = DN_SKB_CB(skb);
    struct sk_buff *skb2;
    int ret = 0;

    if ((skb2 = skb_clone(skb, gfp)) != NULL) {
        ret = cb->xmit_count;
        cb->xmit_count++;
        cb->stamp = jiffies;
        skb2->sk = skb->sk;
        dn_nsp_send(skb2);
    }

    return ret;
}

void dn_nsp_output(struct sock *sk)
{
    struct dn_scp *scp = DN_SK(sk);
    struct sk_buff *skb;
    unsigned int reduce_win = 0;

    /*
     * First we check for otherdata/linkservice messages
     */
    if ((skb = skb_peek(&scp->other_xmit_queue)) != NULL)
        reduce_win = dn_nsp_clone_and_send(skb, GFP_ATOMIC);

    /*
     * If we may not send any data, we don't.
     * If we are still trying to get some other data down the
     * channel, we don't try and send any data.
     */
    if (reduce_win || (scp->flowrem_sw != DN_SEND))
        goto recalc_window;

    if ((skb = skb_peek(&scp->data_xmit_queue)) != NULL)
        reduce_win = dn_nsp_clone_and_send(skb, GFP_ATOMIC);

    /*
     * If we've sent any frame more than once, we cut the
     * send window size in half. There is always a minimum
     * window size of one available.
     */
recalc_window:
    if (reduce_win) {
        scp->snd_window >>= 1;
        if (scp->snd_window < NSP_MIN_WINDOW)
            scp->snd_window = NSP_MIN_WINDOW;
    }
}

int dn_nsp_xmit_timeout(struct sock *sk)
{
    struct dn_scp *scp = DN_SK(sk);

    dn_nsp_output(sk);

    if (!skb_queue_empty(&scp->data_xmit_queue) ||
        !skb_queue_empty(&scp->other_xmit_queue))
        scp->persist = dn_nsp_persist(sk);

    return 0;
}

static inline __le16 *dn_mk_common_header(struct dn_scp *scp, struct sk_buff *skb, unsigned char msgflag, int len)
{
    unsigned char *ptr = skb_push(skb, len);

    BUG_ON(len < 5);

    *ptr++ = msgflag;
    *((__le16 *)ptr) = scp->addrrem;
    ptr += 2;
    *((__le16 *)ptr) = scp->addrloc;
    ptr += 2;
    return (__le16 __force *)ptr;
}

static __le16 *dn_mk_ack_header(struct sock *sk, struct sk_buff *skb, unsigned char msgflag, int hlen, int other)
{
    struct dn_scp *scp = DN_SK(sk);
    unsigned short acknum = scp->numdat_rcv & 0x0FFF;
    unsigned short ackcrs = scp->numoth_rcv & 0x0FFF;
    __le16 *ptr;

    BUG_ON(hlen < 9);

    scp->ackxmt_dat = acknum;
    scp->ackxmt_oth = ackcrs;
    acknum |= 0x8000;
    ackcrs |= 0x8000;

    /* If this is an "other data/ack" message, swap acknum and ackcrs */
    if (other) {
        unsigned short tmp = acknum;
        acknum = ackcrs;
        ackcrs = tmp;
    }

    /* Set "cross subchannel" bit in ackcrs */
    ackcrs |= 0x2000;

    ptr = dn_mk_common_header(scp, skb, msgflag, hlen);

    *ptr++ = cpu_to_le16(acknum);
    *ptr++ = cpu_to_le16(ackcrs);

    return ptr;
}

static __le16 *dn_nsp_mk_data_header(struct sock *sk, struct sk_buff *skb, int oth)
{
    struct dn_scp *scp = DN_SK(sk);
    struct dn_skb_cb *cb = DN_SKB_CB(skb);
    __le16 *ptr = dn_mk_ack_header(sk, skb, cb->nsp_flags, 11, oth);

    if (unlikely(oth)) {
        cb->segnum = scp->numoth;
        seq_add(&scp->numoth, 1);
    } else {
        cb->segnum = scp->numdat;
        seq_add(&scp->numdat, 1);
    }
    *(ptr++) = cpu_to_le16(cb->segnum);

    return ptr;
}

void dn_nsp_queue_xmit(struct sock *sk, struct sk_buff *skb,
            gfp_t gfp, int oth)
{
    struct dn_scp *scp = DN_SK(sk);
    struct dn_skb_cb *cb = DN_SKB_CB(skb);
    unsigned long t = ((scp->nsp_srtt >> 2) + scp->nsp_rttvar) >> 1;

    cb->xmit_count = 0;
    dn_nsp_mk_data_header(sk, skb, oth);

    /*
     * Slow start: If we have been idle for more than
     * one RTT, then reset window to min size.
     */
    if ((jiffies - scp->stamp) > t)
        scp->snd_window = NSP_MIN_WINDOW;

    if (oth)
        skb_queue_tail(&scp->other_xmit_queue, skb);
    else
        skb_queue_tail(&scp->data_xmit_queue, skb);

    if (scp->flowrem_sw != DN_SEND)
        return;

    dn_nsp_clone_and_send(skb, gfp);
}


int dn_nsp_check_xmit_queue(struct sock *sk, struct sk_buff *skb, struct sk_buff_head *q, unsigned short acknum)
{
    struct dn_skb_cb *cb = DN_SKB_CB(skb);
    struct dn_scp *scp = DN_SK(sk);
    struct sk_buff *skb2, *n, *ack = NULL;
    int wakeup = 0;
    int try_retrans = 0;
    unsigned long reftime = cb->stamp;
    unsigned long pkttime;
    unsigned short xmit_count;
    unsigned short segnum;

    skb_queue_walk_safe(q, skb2, n) {
        struct dn_skb_cb *cb2 = DN_SKB_CB(skb2);

        if (dn_before_or_equal(cb2->segnum, acknum))
            ack = skb2;

        /* printk(KERN_DEBUG "ack: %s %04x %04x\n", ack ? "ACK" : "SKIP", (int)cb2->segnum, (int)acknum); */

        if (ack == NULL)
            continue;

        /* printk(KERN_DEBUG "check_xmit_queue: %04x, %d\n", acknum, cb2->xmit_count); */

        /* Does _last_ packet acked have xmit_count > 1 */
        try_retrans = 0;
        /* Remember to wake up the sending process */
        wakeup = 1;
        /* Keep various statistics */
        pkttime = cb2->stamp;
        xmit_count = cb2->xmit_count;
        segnum = cb2->segnum;
        /* Remove and drop ack'ed packet */
        skb_unlink(ack, q);
        kfree_skb(ack);
        ack = NULL;

        /*
         * We don't expect to see acknowledgements for packets we
         * haven't sent yet.
         */
        WARN_ON(xmit_count == 0);

        /*
         * If the packet has only been sent once, we can use it
         * to calculate the RTT and also open the window a little
         * further.
         */
        if (xmit_count == 1) {
            if (dn_equal(segnum, acknum))
                dn_nsp_rtt(sk, (long)(pkttime - reftime));

            if (scp->snd_window < scp->max_window)
                scp->snd_window++;
        }

        /*
         * Packet has been sent more than once. If this is the last
         * packet to be acknowledged then we want to send the next
         * packet in the send queue again (assumes the remote host does
         * go-back-N error control).
         */
        if (xmit_count > 1)
            try_retrans = 1;
    }

    if (try_retrans)
        dn_nsp_output(sk);

    return wakeup;
}

void dn_nsp_send_data_ack(struct sock *sk)
{
    struct sk_buff *skb = NULL;

    if ((skb = dn_alloc_skb(sk, 9, GFP_ATOMIC)) == NULL)
        return;

    skb_reserve(skb, 9);
    dn_mk_ack_header(sk, skb, 0x04, 9, 0);
    dn_nsp_send(skb);
}

void dn_nsp_send_oth_ack(struct sock *sk)
{
    struct sk_buff *skb = NULL;

    if ((skb = dn_alloc_skb(sk, 9, GFP_ATOMIC)) == NULL)
        return;

    skb_reserve(skb, 9);
    dn_mk_ack_header(sk, skb, 0x14, 9, 1);
    dn_nsp_send(skb);
}


void dn_send_conn_ack (struct sock *sk)
{
    struct dn_scp *scp = DN_SK(sk);
    struct sk_buff *skb = NULL;
    struct nsp_conn_ack_msg *msg;

    if ((skb = dn_alloc_skb(sk, 3, sk->sk_allocation)) == NULL)
        return;

    msg = (struct nsp_conn_ack_msg *)skb_put(skb, 3);
    msg->msgflg = 0x24;
    msg->dstaddr = scp->addrrem;

    dn_nsp_send(skb);
}

void dn_nsp_delayed_ack(struct sock *sk)
{
    struct dn_scp *scp = DN_SK(sk);

    if (scp->ackxmt_oth != scp->numoth_rcv)
        dn_nsp_send_oth_ack(sk);

    if (scp->ackxmt_dat != scp->numdat_rcv)
        dn_nsp_send_data_ack(sk);
}

static int dn_nsp_retrans_conn_conf(struct sock *sk)
{
    struct dn_scp *scp = DN_SK(sk);

    if (scp->state == DN_CC)
        dn_send_conn_conf(sk, GFP_ATOMIC);

    return 0;
}

void dn_send_conn_conf(struct sock *sk, gfp_t gfp)
{
    struct dn_scp *scp = DN_SK(sk);
    struct sk_buff *skb = NULL;
    struct nsp_conn_init_msg *msg;
    __u8 len = (__u8)le16_to_cpu(scp->conndata_out.opt_optl);

    if ((skb = dn_alloc_skb(sk, 50 + len, gfp)) == NULL)
        return;

    msg = (struct nsp_conn_init_msg *)skb_put(skb, sizeof(*msg));
    msg->msgflg = 0x28;
    msg->dstaddr = scp->addrrem;
    msg->srcaddr = scp->addrloc;
    msg->services = scp->services_loc;
    msg->info = scp->info_loc;
    msg->segsize = cpu_to_le16(scp->segsize_loc);

    *skb_put(skb,1) = len;

    if (len > 0)
        memcpy(skb_put(skb, len), scp->conndata_out.opt_data, len);


    dn_nsp_send(skb);

    scp->persist = dn_nsp_persist(sk);
    scp->persist_fxn = dn_nsp_retrans_conn_conf;
}


static __inline__ void dn_nsp_do_disc(struct sock *sk, unsigned char msgflg,
            unsigned short reason, gfp_t gfp,
            struct dst_entry *dst,
            int ddl, unsigned char *dd, __le16 rem, __le16 loc)
{
    struct sk_buff *skb = NULL;
    int size = 7 + ddl + ((msgflg == NSP_DISCINIT) ? 1 : 0);
    unsigned char *msg;

    if ((dst == NULL) || (rem == 0)) {
        net_dbg_ratelimited("DECnet: dn_nsp_do_disc: BUG! Please report this to [email protected] rem=%u dst=%p\n",
                    le16_to_cpu(rem), dst);
        return;
    }

    if ((skb = dn_alloc_skb(sk, size, gfp)) == NULL)
        return;

    msg = skb_put(skb, size);
    *msg++ = msgflg;
    *(__le16 *)msg = rem;
    msg += 2;
    *(__le16 *)msg = loc;
    msg += 2;
    *(__le16 *)msg = cpu_to_le16(reason);
    msg += 2;
    if (msgflg == NSP_DISCINIT)
        *msg++ = ddl;

    if (ddl) {
        memcpy(msg, dd, ddl);
    }

    /*
     * This doesn't go via the dn_nsp_send() function since we need
     * to be able to send disc packets out which have no socket
     * associations.
     */
    skb_dst_set(skb, dst_clone(dst));
    dst_output(skb);
}


void dn_nsp_send_disc(struct sock *sk, unsigned char msgflg,
            unsigned short reason, gfp_t gfp)
{
    struct dn_scp *scp = DN_SK(sk);
    int ddl = 0;

    if (msgflg == NSP_DISCINIT)
        ddl = le16_to_cpu(scp->discdata_out.opt_optl);

    if (reason == 0)
        reason = le16_to_cpu(scp->discdata_out.opt_status);

    dn_nsp_do_disc(sk, msgflg, reason, gfp, sk->sk_dst_cache, ddl,
        scp->discdata_out.opt_data, scp->addrrem, scp->addrloc);
}


void dn_nsp_return_disc(struct sk_buff *skb, unsigned char msgflg,
            unsigned short reason)
{
    struct dn_skb_cb *cb = DN_SKB_CB(skb);
    int ddl = 0;
    gfp_t gfp = GFP_ATOMIC;

    dn_nsp_do_disc(NULL, msgflg, reason, gfp, skb_dst(skb), ddl,
            NULL, cb->src_port, cb->dst_port);
}


void dn_nsp_send_link(struct sock *sk, unsigned char lsflags, char fcval)
{
    struct dn_scp *scp = DN_SK(sk);
    struct sk_buff *skb;
    unsigned char *ptr;
    gfp_t gfp = GFP_ATOMIC;

    if ((skb = dn_alloc_skb(sk, DN_MAX_NSP_DATA_HEADER + 2, gfp)) == NULL)
        return;

    skb_reserve(skb, DN_MAX_NSP_DATA_HEADER);
    ptr = skb_put(skb, 2);
    DN_SKB_CB(skb)->nsp_flags = 0x10;
    *ptr++ = lsflags;
    *ptr = fcval;

    dn_nsp_queue_xmit(sk, skb, gfp, 1);

    scp->persist = dn_nsp_persist(sk);
    scp->persist_fxn = dn_nsp_xmit_timeout;
}

static int dn_nsp_retrans_conninit(struct sock *sk)
{
    struct dn_scp *scp = DN_SK(sk);

    if (scp->state == DN_CI)
        dn_nsp_send_conninit(sk, NSP_RCI);

    return 0;
}

void dn_nsp_send_conninit(struct sock *sk, unsigned char msgflg)
{
    struct dn_scp *scp = DN_SK(sk);
    struct nsp_conn_init_msg *msg;
    unsigned char aux;
    unsigned char menuver;
    struct dn_skb_cb *cb;
    unsigned char type = 1;
    gfp_t allocation = (msgflg == NSP_CI) ? sk->sk_allocation : GFP_ATOMIC;
    struct sk_buff *skb = dn_alloc_skb(sk, 200, allocation);

    if (!skb)
        return;

    cb  = DN_SKB_CB(skb);
    msg = (struct nsp_conn_init_msg *)skb_put(skb,sizeof(*msg));

    msg->msgflg = msgflg;
    msg->dstaddr    = 0x0000;       /* Remote Node will assign it*/

    msg->srcaddr    = scp->addrloc;
    msg->services   = scp->services_loc;    /* Requested flow control    */
    msg->info   = scp->info_loc;    /* Version Number            */
    msg->segsize    = cpu_to_le16(scp->segsize_loc);    /* Max segment size  */

    if (scp->peer.sdn_objnum)
        type = 0;

    skb_put(skb, dn_sockaddr2username(&scp->peer,
                      skb_tail_pointer(skb), type));
    skb_put(skb, dn_sockaddr2username(&scp->addr,
                      skb_tail_pointer(skb), 2));

    menuver = DN_MENUVER_ACC | DN_MENUVER_USR;
    if (scp->peer.sdn_flags & SDF_PROXY)
        menuver |= DN_MENUVER_PRX;
    if (scp->peer.sdn_flags & SDF_UICPROXY)
        menuver |= DN_MENUVER_UIC;

    *skb_put(skb, 1) = menuver; /* Menu Version     */

    aux = scp->accessdata.acc_userl;
    *skb_put(skb, 1) = aux;
    if (aux > 0)
        memcpy(skb_put(skb, aux), scp->accessdata.acc_user, aux);

    aux = scp->accessdata.acc_passl;
    *skb_put(skb, 1) = aux;
    if (aux > 0)
        memcpy(skb_put(skb, aux), scp->accessdata.acc_pass, aux);

    aux = scp->accessdata.acc_accl;
    *skb_put(skb, 1) = aux;
    if (aux > 0)
        memcpy(skb_put(skb, aux), scp->accessdata.acc_acc, aux);

    aux = (__u8)le16_to_cpu(scp->conndata_out.opt_optl);
    *skb_put(skb, 1) = aux;
    if (aux > 0)
        memcpy(skb_put(skb, aux), scp->conndata_out.opt_data, aux);

    scp->persist = dn_nsp_persist(sk);
    scp->persist_fxn = dn_nsp_retrans_conninit;

    cb->rt_flags = DN_RT_F_RQR;

    dn_nsp_send(skb);
}