314 lines
8.4 KiB
C
314 lines
8.4 KiB
C
/*
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* llc_station.c - station component of LLC
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*
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* Copyright (c) 1997 by Procom Technology, Inc.
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* 2001-2003 by Arnaldo Carvalho de Melo <acme@conectiva.com.br>
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*
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* This program can be redistributed or modified under the terms of the
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* GNU General Public License as published by the Free Software Foundation.
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* This program is distributed without any warranty or implied warranty
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* of merchantability or fitness for a particular purpose.
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*
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* See the GNU General Public License for more details.
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*/
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/slab.h>
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#include <net/llc.h>
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#include <net/llc_sap.h>
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#include <net/llc_conn.h>
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#include <net/llc_c_ac.h>
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#include <net/llc_s_ac.h>
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#include <net/llc_c_ev.h>
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#include <net/llc_c_st.h>
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#include <net/llc_s_ev.h>
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#include <net/llc_s_st.h>
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#include <net/llc_pdu.h>
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/**
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* struct llc_station - LLC station component
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*
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* SAP and connection resource manager, one per adapter.
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*
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* @mac_sa: MAC source address
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* @sap_list: list of related SAPs
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* @ev_q: events entering state mach.
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* @mac_pdu_q: PDUs ready to send to MAC
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*/
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struct llc_station {
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struct {
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struct sk_buff_head list;
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spinlock_t lock;
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} ev_q;
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struct sk_buff_head mac_pdu_q;
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};
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typedef int (*llc_station_ev_t)(struct sk_buff *skb);
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typedef int (*llc_station_action_t)(struct sk_buff *skb);
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/* Station component state table structure */
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struct llc_station_state_trans {
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llc_station_ev_t ev;
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llc_station_action_t *ev_actions;
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};
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static struct llc_station llc_main_station;
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static int llc_stat_ev_rx_null_dsap_xid_c(struct sk_buff *skb)
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{
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struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);
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return LLC_PDU_IS_CMD(pdu) && /* command PDU */
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LLC_PDU_TYPE_IS_U(pdu) && /* U type PDU */
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LLC_U_PDU_CMD(pdu) == LLC_1_PDU_CMD_XID &&
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!pdu->dsap ? 0 : 1; /* NULL DSAP value */
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}
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static int llc_stat_ev_rx_null_dsap_test_c(struct sk_buff *skb)
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{
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struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);
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return LLC_PDU_IS_CMD(pdu) && /* command PDU */
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LLC_PDU_TYPE_IS_U(pdu) && /* U type PDU */
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LLC_U_PDU_CMD(pdu) == LLC_1_PDU_CMD_TEST &&
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!pdu->dsap ? 0 : 1; /* NULL DSAP */
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}
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/**
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* llc_station_send_pdu - queues PDU to send
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* @skb: Address of the PDU
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*
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* Queues a PDU to send to the MAC layer.
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*/
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static void llc_station_send_pdu(struct sk_buff *skb)
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{
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skb_queue_tail(&llc_main_station.mac_pdu_q, skb);
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while ((skb = skb_dequeue(&llc_main_station.mac_pdu_q)) != NULL)
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if (dev_queue_xmit(skb))
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break;
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}
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static int llc_station_ac_send_xid_r(struct sk_buff *skb)
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{
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u8 mac_da[ETH_ALEN], dsap;
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int rc = 1;
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struct sk_buff *nskb = llc_alloc_frame(NULL, skb->dev, LLC_PDU_TYPE_U,
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sizeof(struct llc_xid_info));
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if (!nskb)
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goto out;
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rc = 0;
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llc_pdu_decode_sa(skb, mac_da);
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llc_pdu_decode_ssap(skb, &dsap);
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llc_pdu_header_init(nskb, LLC_PDU_TYPE_U, 0, dsap, LLC_PDU_RSP);
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llc_pdu_init_as_xid_rsp(nskb, LLC_XID_NULL_CLASS_2, 127);
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rc = llc_mac_hdr_init(nskb, skb->dev->dev_addr, mac_da);
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if (unlikely(rc))
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goto free;
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llc_station_send_pdu(nskb);
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out:
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return rc;
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free:
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kfree_skb(nskb);
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goto out;
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}
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static int llc_station_ac_send_test_r(struct sk_buff *skb)
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{
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u8 mac_da[ETH_ALEN], dsap;
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int rc = 1;
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u32 data_size;
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struct sk_buff *nskb;
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/* The test request command is type U (llc_len = 3) */
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data_size = ntohs(eth_hdr(skb)->h_proto) - 3;
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nskb = llc_alloc_frame(NULL, skb->dev, LLC_PDU_TYPE_U, data_size);
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if (!nskb)
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goto out;
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rc = 0;
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llc_pdu_decode_sa(skb, mac_da);
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llc_pdu_decode_ssap(skb, &dsap);
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llc_pdu_header_init(nskb, LLC_PDU_TYPE_U, 0, dsap, LLC_PDU_RSP);
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llc_pdu_init_as_test_rsp(nskb, skb);
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rc = llc_mac_hdr_init(nskb, skb->dev->dev_addr, mac_da);
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if (unlikely(rc))
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goto free;
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llc_station_send_pdu(nskb);
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out:
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return rc;
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free:
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kfree_skb(nskb);
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goto out;
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}
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/* state transition for LLC_STATION_EV_RX_NULL_DSAP_XID_C event */
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static llc_station_action_t llc_stat_up_state_actions_2[] = {
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[0] = llc_station_ac_send_xid_r,
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[1] = NULL,
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};
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static struct llc_station_state_trans llc_stat_up_state_trans_2 = {
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.ev = llc_stat_ev_rx_null_dsap_xid_c,
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.ev_actions = llc_stat_up_state_actions_2,
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};
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/* state transition for LLC_STATION_EV_RX_NULL_DSAP_TEST_C event */
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static llc_station_action_t llc_stat_up_state_actions_3[] = {
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[0] = llc_station_ac_send_test_r,
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[1] = NULL,
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};
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static struct llc_station_state_trans llc_stat_up_state_trans_3 = {
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.ev = llc_stat_ev_rx_null_dsap_test_c,
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.ev_actions = llc_stat_up_state_actions_3,
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};
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/* array of pointers; one to each transition */
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static struct llc_station_state_trans *llc_stat_up_state_trans [] = {
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&llc_stat_up_state_trans_2,
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&llc_stat_up_state_trans_3,
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NULL,
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};
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/**
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* llc_exec_station_trans_actions - executes actions for transition
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* @trans: Address of the transition
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* @skb: Address of the event that caused the transition
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*
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* Executes actions of a transition of the station state machine. Returns
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* 0 if all actions complete successfully, nonzero otherwise.
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*/
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static u16 llc_exec_station_trans_actions(struct llc_station_state_trans *trans,
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struct sk_buff *skb)
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{
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u16 rc = 0;
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llc_station_action_t *next_action = trans->ev_actions;
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for (; next_action && *next_action; next_action++)
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if ((*next_action)(skb))
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rc = 1;
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return rc;
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}
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/**
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* llc_find_station_trans - finds transition for this event
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* @skb: Address of the event
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*
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* Search thru events of the current state of the station until list
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* exhausted or it's obvious that the event is not valid for the current
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* state. Returns the address of the transition if cound, %NULL otherwise.
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*/
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static struct llc_station_state_trans *
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llc_find_station_trans(struct sk_buff *skb)
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{
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int i = 0;
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struct llc_station_state_trans *rc = NULL;
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struct llc_station_state_trans **next_trans;
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for (next_trans = llc_stat_up_state_trans; next_trans[i]; i++)
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if (!next_trans[i]->ev(skb)) {
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rc = next_trans[i];
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break;
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}
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return rc;
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}
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/**
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* llc_station_free_ev - frees an event
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* @skb: Address of the event
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*
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* Frees an event.
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*/
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static void llc_station_free_ev(struct sk_buff *skb)
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{
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kfree_skb(skb);
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}
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/**
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* llc_station_next_state - processes event and goes to the next state
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* @skb: Address of the event
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*
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* Processes an event, executes any transitions related to that event and
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* updates the state of the station.
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*/
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static u16 llc_station_next_state(struct sk_buff *skb)
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{
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u16 rc = 1;
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struct llc_station_state_trans *trans;
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trans = llc_find_station_trans(skb);
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if (trans)
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/* got the state to which we next transition; perform the
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* actions associated with this transition before actually
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* transitioning to the next state
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*/
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rc = llc_exec_station_trans_actions(trans, skb);
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else
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/* event not recognized in current state; re-queue it for
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* processing again at a later time; return failure
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*/
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rc = 0;
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llc_station_free_ev(skb);
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return rc;
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}
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/**
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* llc_station_service_events - service events in the queue
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*
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* Get an event from the station event queue (if any); attempt to service
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* the event; if event serviced, get the next event (if any) on the event
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* queue; if event not service, re-queue the event on the event queue and
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* attempt to service the next event; when serviced all events in queue,
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* finished; if don't transition to different state, just service all
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* events once; if transition to new state, service all events again.
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* Caller must hold llc_main_station.ev_q.lock.
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*/
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static void llc_station_service_events(void)
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{
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struct sk_buff *skb;
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while ((skb = skb_dequeue(&llc_main_station.ev_q.list)) != NULL)
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llc_station_next_state(skb);
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}
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/**
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* llc_station_state_process - queue event and try to process queue.
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* @skb: Address of the event
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*
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* Queues an event (on the station event queue) for handling by the
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* station state machine and attempts to process any queued-up events.
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*/
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static void llc_station_state_process(struct sk_buff *skb)
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{
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spin_lock_bh(&llc_main_station.ev_q.lock);
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skb_queue_tail(&llc_main_station.ev_q.list, skb);
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llc_station_service_events();
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spin_unlock_bh(&llc_main_station.ev_q.lock);
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}
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/**
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* llc_station_rcv - send received pdu to the station state machine
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* @skb: received frame.
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*
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* Sends data unit to station state machine.
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*/
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static void llc_station_rcv(struct sk_buff *skb)
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{
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llc_station_state_process(skb);
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}
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void __init llc_station_init(void)
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{
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skb_queue_head_init(&llc_main_station.mac_pdu_q);
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skb_queue_head_init(&llc_main_station.ev_q.list);
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spin_lock_init(&llc_main_station.ev_q.lock);
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llc_set_station_handler(llc_station_rcv);
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}
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void llc_station_exit(void)
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{
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llc_set_station_handler(NULL);
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}
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