root/net/llc/llc_if.c

DEFINITIONS

1. llc_build_and_send_pkt
2. llc_establish_connection
3. llc_send_disc

/*
 * llc_if.c - Defines LLC interface to upper layer
 *
 * Copyright (c) 1997 by Procom Technology, Inc.
 *               2001-2003 by Arnaldo Carvalho de Melo <acme@conectiva.com.br>
 *
 * This program can be redistributed or modified under the terms of the
 * GNU General Public License as published by the Free Software Foundation.
 * This program is distributed without any warranty or implied warranty
 * of merchantability or fitness for a particular purpose.
 *
 * See the GNU General Public License for more details.
 */
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/netdevice.h>
#include <asm/errno.h>
#include <net/llc_if.h>
#include <net/llc_sap.h>
#include <net/llc_s_ev.h>
#include <net/llc_conn.h>
#include <net/sock.h>
#include <net/llc_c_ev.h>
#include <net/llc_c_ac.h>
#include <net/llc_c_st.h>
#include <net/tcp_states.h>

/**
 *      llc_build_and_send_pkt - Connection data sending for upper layers.
 *      @sk: connection
 *      @skb: packet to send
 *
 *      This function is called when upper layer wants to send data using
 *      connection oriented communication mode. During sending data, connection
 *      will be locked and received frames and expired timers will be queued.
 *      Returns 0 for success, -ECONNABORTED when the connection already
 *      closed and -EBUSY when sending data is not permitted in this state or
 *      LLC has send an I pdu with p bit set to 1 and is waiting for it's
 *      response.
 */
int llc_build_and_send_pkt(struct sock *sk, struct sk_buff *skb)
{
        struct llc_conn_state_ev *ev;
        int rc = -ECONNABORTED;
        struct llc_sock *llc = llc_sk(sk);

        if (unlikely(llc->state == LLC_CONN_STATE_ADM))
                goto out;
        rc = -EBUSY;
        if (unlikely(llc_data_accept_state(llc->state) || /* data_conn_refuse */
                     llc->p_flag)) {
                llc->failed_data_req = 1;
                goto out;
        }
        ev = llc_conn_ev(skb);
        ev->type      = LLC_CONN_EV_TYPE_PRIM;
        ev->prim      = LLC_DATA_PRIM;
        ev->prim_type = LLC_PRIM_TYPE_REQ;
        skb->dev      = llc->dev;
        rc = llc_conn_state_process(sk, skb);
out:
        return rc;
}

/**
 *      llc_establish_connection - Called by upper layer to establish a conn
 *      @sk: connection
 *      @lmac: local mac address
 *      @dmac: destination mac address
 *      @dsap: destination sap
 *
 *      Upper layer calls this to establish an LLC connection with a remote
 *      machine. This function packages a proper event and sends it connection
 *      component state machine. Success or failure of connection
 *      establishment will inform to upper layer via calling it's confirm
 *      function and passing proper information.
 */
int llc_establish_connection(struct sock *sk, u8 *lmac, u8 *dmac, u8 dsap)
{
        int rc = -EISCONN;
        struct llc_addr laddr, daddr;
        struct sk_buff *skb;
        struct llc_sock *llc = llc_sk(sk);
        struct sock *existing;

        laddr.lsap = llc->sap->laddr.lsap;
        daddr.lsap = dsap;
        memcpy(daddr.mac, dmac, sizeof(daddr.mac));
        memcpy(laddr.mac, lmac, sizeof(laddr.mac));
        existing = llc_lookup_established(llc->sap, &daddr, &laddr);
        if (existing) {
                if (existing->sk_state == TCP_ESTABLISHED) {
                        sk = existing;
                        goto out_put;
                } else
                        sock_put(existing);
        }
        sock_hold(sk);
        rc = -ENOMEM;
        skb = alloc_skb(0, GFP_ATOMIC);
        if (skb) {
                struct llc_conn_state_ev *ev = llc_conn_ev(skb);

                ev->type      = LLC_CONN_EV_TYPE_PRIM;
                ev->prim      = LLC_CONN_PRIM;
                ev->prim_type = LLC_PRIM_TYPE_REQ;
                skb_set_owner_w(skb, sk);
                rc = llc_conn_state_process(sk, skb);
        }
out_put:
        sock_put(sk);
        return rc;
}

/**
 *      llc_send_disc - Called by upper layer to close a connection
 *      @sk: connection to be closed
 *
 *      Upper layer calls this when it wants to close an established LLC
 *      connection with a remote machine. This function packages a proper event
 *      and sends it to connection component state machine. Returns 0 for
 *      success, 1 otherwise.
 */
int llc_send_disc(struct sock *sk)
{
        u16 rc = 1;
        struct llc_conn_state_ev *ev;
        struct sk_buff *skb;

        sock_hold(sk);
        if (sk->sk_type != SOCK_STREAM || sk->sk_state != TCP_ESTABLISHED ||
            llc_sk(sk)->state == LLC_CONN_STATE_ADM ||
            llc_sk(sk)->state == LLC_CONN_OUT_OF_SVC)
                goto out;
        /*
         * Postpone unassigning the connection from its SAP and returning the
         * connection until all ACTIONs have been completely executed
         */
        skb = alloc_skb(0, GFP_ATOMIC);
        if (!skb)
                goto out;
        skb_set_owner_w(skb, sk);
        sk->sk_state  = TCP_CLOSING;
        ev            = llc_conn_ev(skb);
        ev->type      = LLC_CONN_EV_TYPE_PRIM;
        ev->prim      = LLC_DISC_PRIM;
        ev->prim_type = LLC_PRIM_TYPE_REQ;
        rc = llc_conn_state_process(sk, skb);
out:
        sock_put(sk);
        return rc;
}