net/llc/llc_if.c

   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/module.h>
  15 #include <linux/kernel.h>
  16 #include <linux/netdevice.h>
  17 #include <asm/errno.h>
  18 #include <net/llc_if.h>
  19 #include <net/llc_sap.h>
  20 #include <net/llc_s_ev.h>
  21 #include <net/llc_conn.h>
  22 #include <net/sock.h>
  23 #include <net/llc_c_ev.h>
  24 #include <net/llc_c_ac.h>
  25 #include <net/llc_c_st.h>
  26 #include <net/tcp_states.h>
  27
  28 /**
  29  *      llc_build_and_send_pkt - Connection data sending for upper layers.
  30  *      @sk: connection
  31  *      @skb: packet to send
  32  *
  33  *      This function is called when upper layer wants to send data using
  34  *      connection oriented communication mode. During sending data, connection
  35  *      will be locked and received frames and expired timers will be queued.
  36  *      Returns 0 for success, -ECONNABORTED when the connection already
  37  *      closed and -EBUSY when sending data is not permitted in this state or
  38  *      LLC has send an I pdu with p bit set to 1 and is waiting for it's
  39  *      response.
  40  */
  41 int llc_build_and_send_pkt(struct sock *sk, struct sk_buff *skb)
  42 {
  43         struct llc_conn_state_ev *ev;
  44         int rc = -ECONNABORTED;
  45         struct llc_sock *llc = llc_sk(sk);
  46
  47         if (unlikely(llc->state == LLC_CONN_STATE_ADM))
  48                 goto out;
  49         rc = -EBUSY;
  50         if (unlikely(llc_data_accept_state(llc->state) || /* data_conn_refuse */
  51                      llc->p_flag)) {
  52                 llc->failed_data_req = 1;
  53                 goto out;
  54         }
  55         ev = llc_conn_ev(skb);
  56         ev->type      = LLC_CONN_EV_TYPE_PRIM;
  57         ev->prim      = LLC_DATA_PRIM;
  58         ev->prim_type = LLC_PRIM_TYPE_REQ;
  59         skb->dev      = llc->dev;
  60         rc = llc_conn_state_process(sk, skb);
  61 out:
  62         return rc;
  63 }
  64
  65 /**
  66  *      llc_establish_connection - Called by upper layer to establish a conn
  67  *      @sk: connection
  68  *      @lmac: local mac address
  69  *      @dmac: destination mac address
  70  *      @dsap: destination sap
  71  *
  72  *      Upper layer calls this to establish an LLC connection with a remote
  73  *      machine. This function packages a proper event and sends it connection
  74  *      component state machine. Success or failure of connection
  75  *      establishment will inform to upper layer via calling it's confirm
  76  *      function and passing proper information.
  77  */
  78 int llc_establish_connection(struct sock *sk, u8 *lmac, u8 *dmac, u8 dsap)
  79 {
  80         int rc = -EISCONN;
  81         struct llc_addr laddr, daddr;
  82         struct sk_buff *skb;
  83         struct llc_sock *llc = llc_sk(sk);
  84         struct sock *existing;
  85
  86         laddr.lsap = llc->sap->laddr.lsap;
  87         daddr.lsap = dsap;
  88         memcpy(daddr.mac, dmac, sizeof(daddr.mac));
  89         memcpy(laddr.mac, lmac, sizeof(laddr.mac));
  90         existing = llc_lookup_established(llc->sap, &daddr, &laddr);
  91         if (existing) {
  92                 if (existing->sk_state == TCP_ESTABLISHED) {
  93                         sk = existing;
  94                         goto out_put;
  95                 } else
  96                         sock_put(existing);
  97         }
  98         sock_hold(sk);
  99         rc = -ENOMEM;
 100         skb = alloc_skb(0, GFP_ATOMIC);
 101         if (skb) {
 102                 struct llc_conn_state_ev *ev = llc_conn_ev(skb);
 103
 104                 ev->type      = LLC_CONN_EV_TYPE_PRIM;
 105                 ev->prim      = LLC_CONN_PRIM;
 106                 ev->prim_type = LLC_PRIM_TYPE_REQ;
 107                 skb_set_owner_w(skb, sk);
 108                 rc = llc_conn_state_process(sk, skb);
 109         }
 110 out_put:
 111         sock_put(sk);
 112         return rc;
 113 }
 114
 115 /**
 116  *      llc_send_disc - Called by upper layer to close a connection
 117  *      @sk: connection to be closed
 118  *
 119  *      Upper layer calls this when it wants to close an established LLC
 120  *      connection with a remote machine. This function packages a proper event
 121  *      and sends it to connection component state machine. Returns 0 for
 122  *      success, 1 otherwise.
 123  */
 124 int llc_send_disc(struct sock *sk)
 125 {
 126         u16 rc = 1;
 127         struct llc_conn_state_ev *ev;
 128         struct sk_buff *skb;
 129
 130         sock_hold(sk);
 131         if (sk->sk_type != SOCK_STREAM || sk->sk_state != TCP_ESTABLISHED ||
 132             llc_sk(sk)->state == LLC_CONN_STATE_ADM ||
 133             llc_sk(sk)->state == LLC_CONN_OUT_OF_SVC)
 134                 goto out;
 135         /*
 136          * Postpone unassigning the connection from its SAP and returning the
 137          * connection until all ACTIONs have been completely executed
 138          */
 139         skb = alloc_skb(0, GFP_ATOMIC);
 140         if (!skb)
 141                 goto out;
 142         skb_set_owner_w(skb, sk);
 143         sk->sk_state  = TCP_CLOSING;
 144         ev            = llc_conn_ev(skb);
 145         ev->type      = LLC_CONN_EV_TYPE_PRIM;
 146         ev->prim      = LLC_DISC_PRIM;
 147         ev->prim_type = LLC_PRIM_TYPE_REQ;
 148         rc = llc_conn_state_process(sk, skb);
 149 out:
 150         sock_put(sk);
 151         return rc;
 152 }
 153