net/llc/llc_station.c

0001 /*
0002  * llc_station.c - station component of LLC
0003  *
0004  * Copyright (c) 1997 by Procom Technology, Inc.
0005  *       2001-2003 by Arnaldo Carvalho de Melo <acme@conectiva.com.br>
0006  *
0007  * This program can be redistributed or modified under the terms of the
0008  * GNU General Public License as published by the Free Software Foundation.
0009  * This program is distributed without any warranty or implied warranty
0010  * of merchantability or fitness for a particular purpose.
0011  *
0012  * See the GNU General Public License for more details.
0013  */
0014 #include <linux/init.h>
0015 #include <linux/module.h>
0016 #include <linux/slab.h>
0017 #include <net/llc.h>
0018 #include <net/llc_sap.h>
0019 #include <net/llc_conn.h>
0020 #include <net/llc_c_ac.h>
0021 #include <net/llc_s_ac.h>
0022 #include <net/llc_c_ev.h>
0023 #include <net/llc_c_st.h>
0024 #include <net/llc_s_ev.h>
0025 #include <net/llc_s_st.h>
0026 #include <net/llc_pdu.h>
0027
0028 static int llc_stat_ev_rx_null_dsap_xid_c(struct sk_buff *skb)
0029 {
0030     struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);
0031
0032     return LLC_PDU_IS_CMD(pdu) &&           /* command PDU */
0033            LLC_PDU_TYPE_IS_U(pdu) &&        /* U type PDU */
0034            LLC_U_PDU_CMD(pdu) == LLC_1_PDU_CMD_XID &&
0035            !pdu->dsap;              /* NULL DSAP value */
0036 }
0037
0038 static int llc_stat_ev_rx_null_dsap_test_c(struct sk_buff *skb)
0039 {
0040     struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);
0041
0042     return LLC_PDU_IS_CMD(pdu) &&           /* command PDU */
0043            LLC_PDU_TYPE_IS_U(pdu) &&        /* U type PDU */
0044            LLC_U_PDU_CMD(pdu) == LLC_1_PDU_CMD_TEST &&
0045            !pdu->dsap;              /* NULL DSAP */
0046 }
0047
0048 static int llc_station_ac_send_xid_r(struct sk_buff *skb)
0049 {
0050     u8 mac_da[ETH_ALEN], dsap;
0051     int rc = 1;
0052     struct sk_buff *nskb = llc_alloc_frame(NULL, skb->dev, LLC_PDU_TYPE_U,
0053                            sizeof(struct llc_xid_info));
0054
0055     if (!nskb)
0056         goto out;
0057     llc_pdu_decode_sa(skb, mac_da);
0058     llc_pdu_decode_ssap(skb, &dsap);
0059     llc_pdu_header_init(nskb, LLC_PDU_TYPE_U, 0, dsap, LLC_PDU_RSP);
0060     llc_pdu_init_as_xid_rsp(nskb, LLC_XID_NULL_CLASS_2, 127);
0061     rc = llc_mac_hdr_init(nskb, skb->dev->dev_addr, mac_da);
0062     if (unlikely(rc))
0063         goto free;
0064     dev_queue_xmit(nskb);
0065 out:
0066     return rc;
0067 free:
0068     kfree_skb(nskb);
0069     goto out;
0070 }
0071
0072 static int llc_station_ac_send_test_r(struct sk_buff *skb)
0073 {
0074     u8 mac_da[ETH_ALEN], dsap;
0075     int rc = 1;
0076     u32 data_size;
0077     struct sk_buff *nskb;
0078
0079     /* The test request command is type U (llc_len = 3) */
0080     data_size = ntohs(eth_hdr(skb)->h_proto) - 3;
0081     nskb = llc_alloc_frame(NULL, skb->dev, LLC_PDU_TYPE_U, data_size);
0082
0083     if (!nskb)
0084         goto out;
0085     llc_pdu_decode_sa(skb, mac_da);
0086     llc_pdu_decode_ssap(skb, &dsap);
0087     llc_pdu_header_init(nskb, LLC_PDU_TYPE_U, 0, dsap, LLC_PDU_RSP);
0088     llc_pdu_init_as_test_rsp(nskb, skb);
0089     rc = llc_mac_hdr_init(nskb, skb->dev->dev_addr, mac_da);
0090     if (unlikely(rc))
0091         goto free;
0092     dev_queue_xmit(nskb);
0093 out:
0094     return rc;
0095 free:
0096     kfree_skb(nskb);
0097     goto out;
0098 }
0099
0100 /**
0101  *  llc_station_rcv - send received pdu to the station state machine
0102  *  @skb: received frame.
0103  *
0104  *  Sends data unit to station state machine.
0105  */
0106 static void llc_station_rcv(struct sk_buff *skb)
0107 {
0108     if (llc_stat_ev_rx_null_dsap_xid_c(skb))
0109         llc_station_ac_send_xid_r(skb);
0110     else if (llc_stat_ev_rx_null_dsap_test_c(skb))
0111         llc_station_ac_send_test_r(skb);
0112     kfree_skb(skb);
0113 }
0114
0115 void __init llc_station_init(void)
0116 {
0117     llc_set_station_handler(llc_station_rcv);
0118 }
0119
0120 void llc_station_exit(void)
0121 {
0122     llc_set_station_handler(NULL);
0123 }