linux/net/llc/llc_if.c
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   1/*
   2 * llc_if.c - Defines LLC interface to upper layer
   3 *
   4 * Copyright (c) 1997 by Procom Technology, Inc.
   5 *               2001-2003 by Arnaldo Carvalho de Melo <acme@conectiva.com.br>
   6 *
   7 * This program can be redistributed or modified under the terms of the
   8 * GNU General Public License as published by the Free Software Foundation.
   9 * This program is distributed without any warranty or implied warranty
  10 * of merchantability or fitness for a particular purpose.
  11 *
  12 * See the GNU General Public License for more details.
  13 */
  14#include <linux/gfp.h>
  15#include <linux/module.h>
  16#include <linux/kernel.h>
  17#include <linux/netdevice.h>
  18#include <asm/errno.h>
  19#include <net/llc_if.h>
  20#include <net/llc_sap.h>
  21#include <net/llc_s_ev.h>
  22#include <net/llc_conn.h>
  23#include <net/sock.h>
  24#include <net/llc_c_ev.h>
  25#include <net/llc_c_ac.h>
  26#include <net/llc_c_st.h>
  27#include <net/tcp_states.h>
  28
  29/**
  30 *      llc_build_and_send_pkt - Connection data sending for upper layers.
  31 *      @sk: connection
  32 *      @skb: packet to send
  33 *
  34 *      This function is called when upper layer wants to send data using
  35 *      connection oriented communication mode. During sending data, connection
  36 *      will be locked and received frames and expired timers will be queued.
  37 *      Returns 0 for success, -ECONNABORTED when the connection already
  38 *      closed and -EBUSY when sending data is not permitted in this state or
  39 *      LLC has send an I pdu with p bit set to 1 and is waiting for it's
  40 *      response.
  41 */
  42int llc_build_and_send_pkt(struct sock *sk, struct sk_buff *skb)
  43{
  44        struct llc_conn_state_ev *ev;
  45        int rc = -ECONNABORTED;
  46        struct llc_sock *llc = llc_sk(sk);
  47
  48        if (unlikely(llc->state == LLC_CONN_STATE_ADM))
  49                goto out;
  50        rc = -EBUSY;
  51        if (unlikely(llc_data_accept_state(llc->state) || /* data_conn_refuse */
  52                     llc->p_flag)) {
  53                llc->failed_data_req = 1;
  54                goto out;
  55        }
  56        ev = llc_conn_ev(skb);
  57        ev->type      = LLC_CONN_EV_TYPE_PRIM;
  58        ev->prim      = LLC_DATA_PRIM;
  59        ev->prim_type = LLC_PRIM_TYPE_REQ;
  60        skb->dev      = llc->dev;
  61        rc = llc_conn_state_process(sk, skb);
  62out:
  63        return rc;
  64}
  65
  66/**
  67 *      llc_establish_connection - Called by upper layer to establish a conn
  68 *      @sk: connection
  69 *      @lmac: local mac address
  70 *      @dmac: destination mac address
  71 *      @dsap: destination sap
  72 *
  73 *      Upper layer calls this to establish an LLC connection with a remote
  74 *      machine. This function packages a proper event and sends it connection
  75 *      component state machine. Success or failure of connection
  76 *      establishment will inform to upper layer via calling it's confirm
  77 *      function and passing proper information.
  78 */
  79int llc_establish_connection(struct sock *sk, u8 *lmac, u8 *dmac, u8 dsap)
  80{
  81        int rc = -EISCONN;
  82        struct llc_addr laddr, daddr;
  83        struct sk_buff *skb;
  84        struct llc_sock *llc = llc_sk(sk);
  85        struct sock *existing;
  86
  87        laddr.lsap = llc->sap->laddr.lsap;
  88        daddr.lsap = dsap;
  89        memcpy(daddr.mac, dmac, sizeof(daddr.mac));
  90        memcpy(laddr.mac, lmac, sizeof(laddr.mac));
  91        existing = llc_lookup_established(llc->sap, &daddr, &laddr);
  92        if (existing) {
  93                if (existing->sk_state == TCP_ESTABLISHED) {
  94                        sk = existing;
  95                        goto out_put;
  96                } else
  97                        sock_put(existing);
  98        }
  99        sock_hold(sk);
 100        rc = -ENOMEM;
 101        skb = alloc_skb(0, GFP_ATOMIC);
 102        if (skb) {
 103                struct llc_conn_state_ev *ev = llc_conn_ev(skb);
 104
 105                ev->type      = LLC_CONN_EV_TYPE_PRIM;
 106                ev->prim      = LLC_CONN_PRIM;
 107                ev->prim_type = LLC_PRIM_TYPE_REQ;
 108                skb_set_owner_w(skb, sk);
 109                rc = llc_conn_state_process(sk, skb);
 110        }
 111out_put:
 112        sock_put(sk);
 113        return rc;
 114}
 115
 116/**
 117 *      llc_send_disc - Called by upper layer to close a connection
 118 *      @sk: connection to be closed
 119 *
 120 *      Upper layer calls this when it wants to close an established LLC
 121 *      connection with a remote machine. This function packages a proper event
 122 *      and sends it to connection component state machine. Returns 0 for
 123 *      success, 1 otherwise.
 124 */
 125int llc_send_disc(struct sock *sk)
 126{
 127        u16 rc = 1;
 128        struct llc_conn_state_ev *ev;
 129        struct sk_buff *skb;
 130
 131        sock_hold(sk);
 132        if (sk->sk_type != SOCK_STREAM || sk->sk_state != TCP_ESTABLISHED ||
 133            llc_sk(sk)->state == LLC_CONN_STATE_ADM ||
 134            llc_sk(sk)->state == LLC_CONN_OUT_OF_SVC)
 135                goto out;
 136        /*
 137         * Postpone unassigning the connection from its SAP and returning the
 138         * connection until all ACTIONs have been completely executed
 139         */
 140        skb = alloc_skb(0, GFP_ATOMIC);
 141        if (!skb)
 142                goto out;
 143        skb_set_owner_w(skb, sk);
 144        sk->sk_state  = TCP_CLOSING;
 145        ev            = llc_conn_ev(skb);
 146        ev->type      = LLC_CONN_EV_TYPE_PRIM;
 147        ev->prim      = LLC_DISC_PRIM;
 148        ev->prim_type = LLC_PRIM_TYPE_REQ;
 149        rc = llc_conn_state_process(sk, skb);
 150out:
 151        sock_put(sk);
 152        return rc;
 153}
 154
 155
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