llc_sap.c revision d389424e00f9097cd24b3df4ca0ab7221f140eeb
1/* 2 * llc_sap.c - driver routines for SAP component. 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 15#include <net/llc.h> 16#include <net/llc_if.h> 17#include <net/llc_conn.h> 18#include <net/llc_pdu.h> 19#include <net/llc_sap.h> 20#include <net/llc_s_ac.h> 21#include <net/llc_s_ev.h> 22#include <net/llc_s_st.h> 23#include <net/sock.h> 24#include <net/tcp_states.h> 25#include <linux/llc.h> 26 27/** 28 * llc_alloc_frame - allocates sk_buff for frame 29 * @dev: network device this skb will be sent over 30 * 31 * Allocates an sk_buff for frame and initializes sk_buff fields. 32 * Returns allocated skb or %NULL when out of memory. 33 */ 34struct sk_buff *llc_alloc_frame(struct sock *sk, struct net_device *dev) 35{ 36 struct sk_buff *skb = alloc_skb(128, GFP_ATOMIC); 37 38 if (skb) { 39 skb_reserve(skb, 50); 40 skb->nh.raw = skb->h.raw = skb->data; 41 skb->protocol = htons(ETH_P_802_2); 42 skb->dev = dev; 43 skb->mac.raw = skb->head; 44 if (sk != NULL) 45 skb_set_owner_w(skb, sk); 46 } 47 return skb; 48} 49 50void llc_save_primitive(struct sock *sk, struct sk_buff* skb, u8 prim) 51{ 52 struct sockaddr_llc *addr = llc_ui_skb_cb(skb); 53 54 /* save primitive for use by the user. */ 55 addr->sllc_family = sk->sk_family; 56 addr->sllc_arphrd = skb->dev->type; 57 addr->sllc_test = prim == LLC_TEST_PRIM; 58 addr->sllc_xid = prim == LLC_XID_PRIM; 59 addr->sllc_ua = prim == LLC_DATAUNIT_PRIM; 60 llc_pdu_decode_sa(skb, addr->sllc_mac); 61 llc_pdu_decode_ssap(skb, &addr->sllc_sap); 62} 63 64/** 65 * llc_sap_rtn_pdu - Informs upper layer on rx of an UI, XID or TEST pdu. 66 * @sap: pointer to SAP 67 * @skb: received pdu 68 */ 69void llc_sap_rtn_pdu(struct llc_sap *sap, struct sk_buff *skb) 70{ 71 struct llc_sap_state_ev *ev = llc_sap_ev(skb); 72 struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb); 73 74 switch (LLC_U_PDU_RSP(pdu)) { 75 case LLC_1_PDU_CMD_TEST: 76 ev->prim = LLC_TEST_PRIM; break; 77 case LLC_1_PDU_CMD_XID: 78 ev->prim = LLC_XID_PRIM; break; 79 case LLC_1_PDU_CMD_UI: 80 ev->prim = LLC_DATAUNIT_PRIM; break; 81 } 82 ev->ind_cfm_flag = LLC_IND; 83} 84 85/** 86 * llc_find_sap_trans - finds transition for event 87 * @sap: pointer to SAP 88 * @skb: happened event 89 * 90 * This function finds transition that matches with happened event. 91 * Returns the pointer to found transition on success or %NULL for 92 * failure. 93 */ 94static struct llc_sap_state_trans *llc_find_sap_trans(struct llc_sap *sap, 95 struct sk_buff* skb) 96{ 97 int i = 0; 98 struct llc_sap_state_trans *rc = NULL; 99 struct llc_sap_state_trans **next_trans; 100 struct llc_sap_state *curr_state = &llc_sap_state_table[sap->state - 1]; 101 /* 102 * Search thru events for this state until list exhausted or until 103 * its obvious the event is not valid for the current state 104 */ 105 for (next_trans = curr_state->transitions; next_trans[i]->ev; i++) 106 if (!next_trans[i]->ev(sap, skb)) { 107 rc = next_trans[i]; /* got event match; return it */ 108 break; 109 } 110 return rc; 111} 112 113/** 114 * llc_exec_sap_trans_actions - execute actions related to event 115 * @sap: pointer to SAP 116 * @trans: pointer to transition that it's actions must be performed 117 * @skb: happened event. 118 * 119 * This function executes actions that is related to happened event. 120 * Returns 0 for success and 1 for failure of at least one action. 121 */ 122static int llc_exec_sap_trans_actions(struct llc_sap *sap, 123 struct llc_sap_state_trans *trans, 124 struct sk_buff *skb) 125{ 126 int rc = 0; 127 llc_sap_action_t *next_action = trans->ev_actions; 128 129 for (; next_action && *next_action; next_action++) 130 if ((*next_action)(sap, skb)) 131 rc = 1; 132 return rc; 133} 134 135/** 136 * llc_sap_next_state - finds transition, execs actions & change SAP state 137 * @sap: pointer to SAP 138 * @skb: happened event 139 * 140 * This function finds transition that matches with happened event, then 141 * executes related actions and finally changes state of SAP. It returns 142 * 0 on success and 1 for failure. 143 */ 144static int llc_sap_next_state(struct llc_sap *sap, struct sk_buff *skb) 145{ 146 int rc = 1; 147 struct llc_sap_state_trans *trans; 148 149 if (sap->state > LLC_NR_SAP_STATES) 150 goto out; 151 trans = llc_find_sap_trans(sap, skb); 152 if (!trans) 153 goto out; 154 /* 155 * Got the state to which we next transition; perform the actions 156 * associated with this transition before actually transitioning to the 157 * next state 158 */ 159 rc = llc_exec_sap_trans_actions(sap, trans, skb); 160 if (rc) 161 goto out; 162 /* 163 * Transition SAP to next state if all actions execute successfully 164 */ 165 sap->state = trans->next_state; 166out: 167 return rc; 168} 169 170/** 171 * llc_sap_state_process - sends event to SAP state machine 172 * @sap: sap to use 173 * @skb: pointer to occurred event 174 * 175 * After executing actions of the event, upper layer will be indicated 176 * if needed(on receiving an UI frame). sk can be null for the 177 * datalink_proto case. 178 */ 179static void llc_sap_state_process(struct llc_sap *sap, struct sk_buff *skb) 180{ 181 struct llc_sap_state_ev *ev = llc_sap_ev(skb); 182 183 /* 184 * We have to hold the skb, because llc_sap_next_state 185 * will kfree it in the sending path and we need to 186 * look at the skb->cb, where we encode llc_sap_state_ev. 187 */ 188 skb_get(skb); 189 ev->ind_cfm_flag = 0; 190 llc_sap_next_state(sap, skb); 191 if (ev->ind_cfm_flag == LLC_IND) { 192 if (skb->sk->sk_state == TCP_LISTEN) 193 kfree_skb(skb); 194 else { 195 llc_save_primitive(skb->sk, skb, ev->prim); 196 197 /* queue skb to the user. */ 198 if (sock_queue_rcv_skb(skb->sk, skb)) 199 kfree_skb(skb); 200 } 201 } 202 kfree_skb(skb); 203} 204 205/** 206 * llc_build_and_send_test_pkt - TEST interface for upper layers. 207 * @sap: sap to use 208 * @skb: packet to send 209 * @dmac: destination mac address 210 * @dsap: destination sap 211 * 212 * This function is called when upper layer wants to send a TEST pdu. 213 * Returns 0 for success, 1 otherwise. 214 */ 215void llc_build_and_send_test_pkt(struct llc_sap *sap, 216 struct sk_buff *skb, u8 *dmac, u8 dsap) 217{ 218 struct llc_sap_state_ev *ev = llc_sap_ev(skb); 219 220 ev->saddr.lsap = sap->laddr.lsap; 221 ev->daddr.lsap = dsap; 222 memcpy(ev->saddr.mac, skb->dev->dev_addr, IFHWADDRLEN); 223 memcpy(ev->daddr.mac, dmac, IFHWADDRLEN); 224 225 ev->type = LLC_SAP_EV_TYPE_PRIM; 226 ev->prim = LLC_TEST_PRIM; 227 ev->prim_type = LLC_PRIM_TYPE_REQ; 228 llc_sap_state_process(sap, skb); 229} 230 231/** 232 * llc_build_and_send_xid_pkt - XID interface for upper layers 233 * @sap: sap to use 234 * @skb: packet to send 235 * @dmac: destination mac address 236 * @dsap: destination sap 237 * 238 * This function is called when upper layer wants to send a XID pdu. 239 * Returns 0 for success, 1 otherwise. 240 */ 241void llc_build_and_send_xid_pkt(struct llc_sap *sap, struct sk_buff *skb, 242 u8 *dmac, u8 dsap) 243{ 244 struct llc_sap_state_ev *ev = llc_sap_ev(skb); 245 246 ev->saddr.lsap = sap->laddr.lsap; 247 ev->daddr.lsap = dsap; 248 memcpy(ev->saddr.mac, skb->dev->dev_addr, IFHWADDRLEN); 249 memcpy(ev->daddr.mac, dmac, IFHWADDRLEN); 250 251 ev->type = LLC_SAP_EV_TYPE_PRIM; 252 ev->prim = LLC_XID_PRIM; 253 ev->prim_type = LLC_PRIM_TYPE_REQ; 254 llc_sap_state_process(sap, skb); 255} 256 257/** 258 * llc_sap_rcv - sends received pdus to the sap state machine 259 * @sap: current sap component structure. 260 * @skb: received frame. 261 * 262 * Sends received pdus to the sap state machine. 263 */ 264static void llc_sap_rcv(struct llc_sap *sap, struct sk_buff *skb) 265{ 266 struct llc_sap_state_ev *ev = llc_sap_ev(skb); 267 268 ev->type = LLC_SAP_EV_TYPE_PDU; 269 ev->reason = 0; 270 llc_sap_state_process(sap, skb); 271} 272 273/** 274 * llc_lookup_dgram - Finds dgram socket for the local sap/mac 275 * @sap: SAP 276 * @laddr: address of local LLC (MAC + SAP) 277 * 278 * Search socket list of the SAP and finds connection using the local 279 * mac, and local sap. Returns pointer for socket found, %NULL otherwise. 280 */ 281static struct sock *llc_lookup_dgram(struct llc_sap *sap, 282 struct llc_addr *laddr) 283{ 284 struct sock *rc; 285 struct hlist_node *node; 286 287 read_lock_bh(&sap->sk_list.lock); 288 sk_for_each(rc, node, &sap->sk_list.list) { 289 struct llc_sock *llc = llc_sk(rc); 290 291 if (rc->sk_type == SOCK_DGRAM && 292 llc->laddr.lsap == laddr->lsap && 293 llc_mac_match(llc->laddr.mac, laddr->mac)) { 294 sock_hold(rc); 295 goto found; 296 } 297 } 298 rc = NULL; 299found: 300 read_unlock_bh(&sap->sk_list.lock); 301 return rc; 302} 303 304void llc_sap_handler(struct llc_sap *sap, struct sk_buff *skb) 305{ 306 struct llc_addr laddr; 307 struct sock *sk; 308 309 llc_pdu_decode_da(skb, laddr.mac); 310 llc_pdu_decode_dsap(skb, &laddr.lsap); 311 312 sk = llc_lookup_dgram(sap, &laddr); 313 if (sk) { 314 skb_set_owner_r(skb, sk); 315 llc_sap_rcv(sap, skb); 316 sock_put(sk); 317 } else 318 kfree_skb(skb); 319} 320