net/llc/llc_station.c

   1 /*
   2  * llc_station.c - station component of LLC
   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/init.h>
  15 #include <linux/module.h>
  16 #include <linux/slab.h>
  17 #include <net/llc.h>
  18 #include <net/llc_sap.h>
  19 #include <net/llc_conn.h>
  20 #include <net/llc_c_ac.h>
  21 #include <net/llc_s_ac.h>
  22 #include <net/llc_c_ev.h>
  23 #include <net/llc_c_st.h>
  24 #include <net/llc_s_ev.h>
  25 #include <net/llc_s_st.h>
  26 #include <net/llc_pdu.h>
  27
  28 static int llc_stat_ev_rx_null_dsap_xid_c(struct sk_buff *skb)
  29 {
  30         struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);
  31
  32         return LLC_PDU_IS_CMD(pdu) &&                   /* command PDU */
  33                LLC_PDU_TYPE_IS_U(pdu) &&                /* U type PDU */
  34                LLC_U_PDU_CMD(pdu) == LLC_1_PDU_CMD_XID &&
  35                !pdu->dsap ? 0 : 1;                      /* NULL DSAP value */
  36 }
  37
  38 static int llc_stat_ev_rx_null_dsap_test_c(struct sk_buff *skb)
  39 {
  40         struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);
  41
  42         return LLC_PDU_IS_CMD(pdu) &&                   /* command PDU */
  43                LLC_PDU_TYPE_IS_U(pdu) &&                /* U type PDU */
  44                LLC_U_PDU_CMD(pdu) == LLC_1_PDU_CMD_TEST &&
  45                !pdu->dsap ? 0 : 1;                      /* NULL DSAP */
  46 }
  47
  48 static int llc_station_ac_send_xid_r(struct sk_buff *skb)
  49 {
  50         u8 mac_da[ETH_ALEN], dsap;
  51         int rc = 1;
  52         struct sk_buff *nskb = llc_alloc_frame(NULL, skb->dev, LLC_PDU_TYPE_U,
  53                                                sizeof(struct llc_xid_info));
  54
  55         if (!nskb)
  56                 goto out;
  57         rc = 0;
  58         llc_pdu_decode_sa(skb, mac_da);
  59         llc_pdu_decode_ssap(skb, &dsap);
  60         llc_pdu_header_init(nskb, LLC_PDU_TYPE_U, 0, dsap, LLC_PDU_RSP);
  61         llc_pdu_init_as_xid_rsp(nskb, LLC_XID_NULL_CLASS_2, 127);
  62         rc = llc_mac_hdr_init(nskb, skb->dev->dev_addr, mac_da);
  63         if (unlikely(rc))
  64                 goto free;
  65         dev_queue_xmit(nskb);
  66 out:
  67         return rc;
  68 free:
  69         kfree_skb(nskb);
  70         goto out;
  71 }
  72
  73 static int llc_station_ac_send_test_r(struct sk_buff *skb)
  74 {
  75         u8 mac_da[ETH_ALEN], dsap;
  76         int rc = 1;
  77         u32 data_size;
  78         struct sk_buff *nskb;
  79
  80         /* The test request command is type U (llc_len = 3) */
  81         data_size = ntohs(eth_hdr(skb)->h_proto) - 3;
  82         nskb = llc_alloc_frame(NULL, skb->dev, LLC_PDU_TYPE_U, data_size);
  83
  84         if (!nskb)
  85                 goto out;
  86         rc = 0;
  87         llc_pdu_decode_sa(skb, mac_da);
  88         llc_pdu_decode_ssap(skb, &dsap);
  89         llc_pdu_header_init(nskb, LLC_PDU_TYPE_U, 0, dsap, LLC_PDU_RSP);
  90         llc_pdu_init_as_test_rsp(nskb, skb);
  91         rc = llc_mac_hdr_init(nskb, skb->dev->dev_addr, mac_da);
  92         if (unlikely(rc))
  93                 goto free;
  94         dev_queue_xmit(nskb);
  95 out:
  96         return rc;
  97 free:
  98         kfree_skb(nskb);
  99         goto out;
 100 }
 101
 102 /**
 103  *      llc_station_rcv - send received pdu to the station state machine
 104  *      @skb: received frame.
 105  *
 106  *      Sends data unit to station state machine.
 107  */
 108 static void llc_station_rcv(struct sk_buff *skb)
 109 {
 110         if (llc_stat_ev_rx_null_dsap_xid_c(skb))
 111                 llc_station_ac_send_xid_r(skb);
 112         else if (llc_stat_ev_rx_null_dsap_test_c(skb))
 113                 llc_station_ac_send_test_r(skb);
 114         kfree_skb(skb);
 115 }
 116
 117 void __init llc_station_init(void)
 118 {
 119         llc_set_station_handler(llc_station_rcv);
 120 }
 121
 122 void llc_station_exit(void)
 123 {
 124         llc_set_station_handler(NULL);
 125 }