llc_sap.c revision c752f0739f09b803aed191c4765a3b6650a08653
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 * 30 * Allocates an sk_buff for frame and initializes sk_buff fields. 31 * Returns allocated skb or %NULL when out of memory. 32 */ 33struct sk_buff *llc_alloc_frame(void) 34{ 35 struct sk_buff *skb = alloc_skb(128, GFP_ATOMIC); 36 37 if (skb) { 38 skb_reserve(skb, 50); 39 skb->nh.raw = skb->h.raw = skb->data; 40 skb->protocol = htons(ETH_P_802_2); 41 skb->dev = dev_base->next; 42 skb->mac.raw = skb->head; 43 } 44 return skb; 45} 46 47void llc_save_primitive(struct sk_buff* skb, u8 prim) 48{ 49 struct sockaddr_llc *addr = llc_ui_skb_cb(skb); 50 51 /* save primitive for use by the user. */ 52 addr->sllc_family = skb->sk->sk_family; 53 addr->sllc_arphrd = skb->dev->type; 54 addr->sllc_test = prim == LLC_TEST_PRIM; 55 addr->sllc_xid = prim == LLC_XID_PRIM; 56 addr->sllc_ua = prim == LLC_DATAUNIT_PRIM; 57 llc_pdu_decode_sa(skb, addr->sllc_mac); 58 llc_pdu_decode_ssap(skb, &addr->sllc_sap); 59} 60 61/** 62 * llc_sap_rtn_pdu - Informs upper layer on rx of an UI, XID or TEST pdu. 63 * @sap: pointer to SAP 64 * @skb: received pdu 65 */ 66void llc_sap_rtn_pdu(struct llc_sap *sap, struct sk_buff *skb) 67{ 68 struct llc_sap_state_ev *ev = llc_sap_ev(skb); 69 struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb); 70 71 switch (LLC_U_PDU_RSP(pdu)) { 72 case LLC_1_PDU_CMD_TEST: 73 ev->prim = LLC_TEST_PRIM; break; 74 case LLC_1_PDU_CMD_XID: 75 ev->prim = LLC_XID_PRIM; break; 76 case LLC_1_PDU_CMD_UI: 77 ev->prim = LLC_DATAUNIT_PRIM; break; 78 } 79 ev->ind_cfm_flag = LLC_IND; 80} 81 82/** 83 * llc_find_sap_trans - finds transition for event 84 * @sap: pointer to SAP 85 * @skb: happened event 86 * 87 * This function finds transition that matches with happened event. 88 * Returns the pointer to found transition on success or %NULL for 89 * failure. 90 */ 91static struct llc_sap_state_trans *llc_find_sap_trans(struct llc_sap *sap, 92 struct sk_buff* skb) 93{ 94 int i = 0; 95 struct llc_sap_state_trans *rc = NULL; 96 struct llc_sap_state_trans **next_trans; 97 struct llc_sap_state *curr_state = &llc_sap_state_table[sap->state - 1]; 98 /* 99 * Search thru events for this state until list exhausted or until 100 * its obvious the event is not valid for the current state 101 */ 102 for (next_trans = curr_state->transitions; next_trans[i]->ev; i++) 103 if (!next_trans[i]->ev(sap, skb)) { 104 rc = next_trans[i]; /* got event match; return it */ 105 break; 106 } 107 return rc; 108} 109 110/** 111 * llc_exec_sap_trans_actions - execute actions related to event 112 * @sap: pointer to SAP 113 * @trans: pointer to transition that it's actions must be performed 114 * @skb: happened event. 115 * 116 * This function executes actions that is related to happened event. 117 * Returns 0 for success and 1 for failure of at least one action. 118 */ 119static int llc_exec_sap_trans_actions(struct llc_sap *sap, 120 struct llc_sap_state_trans *trans, 121 struct sk_buff *skb) 122{ 123 int rc = 0; 124 llc_sap_action_t *next_action = trans->ev_actions; 125 126 for (; next_action && *next_action; next_action++) 127 if ((*next_action)(sap, skb)) 128 rc = 1; 129 return rc; 130} 131 132/** 133 * llc_sap_next_state - finds transition, execs actions & change SAP state 134 * @sap: pointer to SAP 135 * @skb: happened event 136 * 137 * This function finds transition that matches with happened event, then 138 * executes related actions and finally changes state of SAP. It returns 139 * 0 on success and 1 for failure. 140 */ 141static int llc_sap_next_state(struct llc_sap *sap, struct sk_buff *skb) 142{ 143 int rc = 1; 144 struct llc_sap_state_trans *trans; 145 146 if (sap->state > LLC_NR_SAP_STATES) 147 goto out; 148 trans = llc_find_sap_trans(sap, skb); 149 if (!trans) 150 goto out; 151 /* 152 * Got the state to which we next transition; perform the actions 153 * associated with this transition before actually transitioning to the 154 * next state 155 */ 156 rc = llc_exec_sap_trans_actions(sap, trans, skb); 157 if (rc) 158 goto out; 159 /* 160 * Transition SAP to next state if all actions execute successfully 161 */ 162 sap->state = trans->next_state; 163out: 164 return rc; 165} 166 167/** 168 * llc_sap_state_process - sends event to SAP state machine 169 * @sap: sap to use 170 * @skb: pointer to occurred event 171 * 172 * After executing actions of the event, upper layer will be indicated 173 * if needed(on receiving an UI frame). sk can be null for the 174 * datalink_proto case. 175 */ 176static void llc_sap_state_process(struct llc_sap *sap, struct sk_buff *skb) 177{ 178 struct llc_sap_state_ev *ev = llc_sap_ev(skb); 179 180 /* 181 * We have to hold the skb, because llc_sap_next_state 182 * will kfree it in the sending path and we need to 183 * look at the skb->cb, where we encode llc_sap_state_ev. 184 */ 185 skb_get(skb); 186 ev->ind_cfm_flag = 0; 187 llc_sap_next_state(sap, skb); 188 if (ev->ind_cfm_flag == LLC_IND) { 189 if (skb->sk->sk_state == TCP_LISTEN) 190 kfree_skb(skb); 191 else { 192 llc_save_primitive(skb, ev->prim); 193 194 /* queue skb to the user. */ 195 if (sock_queue_rcv_skb(skb->sk, skb)) 196 kfree_skb(skb); 197 } 198 } 199 kfree_skb(skb); 200} 201 202/** 203 * llc_build_and_send_test_pkt - TEST interface for upper layers. 204 * @sap: sap to use 205 * @skb: packet to send 206 * @dmac: destination mac address 207 * @dsap: destination sap 208 * 209 * This function is called when upper layer wants to send a TEST pdu. 210 * Returns 0 for success, 1 otherwise. 211 */ 212void llc_build_and_send_test_pkt(struct llc_sap *sap, 213 struct sk_buff *skb, u8 *dmac, u8 dsap) 214{ 215 struct llc_sap_state_ev *ev = llc_sap_ev(skb); 216 217 ev->saddr.lsap = sap->laddr.lsap; 218 ev->daddr.lsap = dsap; 219 memcpy(ev->saddr.mac, skb->dev->dev_addr, IFHWADDRLEN); 220 memcpy(ev->daddr.mac, dmac, IFHWADDRLEN); 221 222 ev->type = LLC_SAP_EV_TYPE_PRIM; 223 ev->prim = LLC_TEST_PRIM; 224 ev->prim_type = LLC_PRIM_TYPE_REQ; 225 llc_sap_state_process(sap, skb); 226} 227 228/** 229 * llc_build_and_send_xid_pkt - XID interface for upper layers 230 * @sap: sap to use 231 * @skb: packet to send 232 * @dmac: destination mac address 233 * @dsap: destination sap 234 * 235 * This function is called when upper layer wants to send a XID pdu. 236 * Returns 0 for success, 1 otherwise. 237 */ 238void llc_build_and_send_xid_pkt(struct llc_sap *sap, struct sk_buff *skb, 239 u8 *dmac, u8 dsap) 240{ 241 struct llc_sap_state_ev *ev = llc_sap_ev(skb); 242 243 ev->saddr.lsap = sap->laddr.lsap; 244 ev->daddr.lsap = dsap; 245 memcpy(ev->saddr.mac, skb->dev->dev_addr, IFHWADDRLEN); 246 memcpy(ev->daddr.mac, dmac, IFHWADDRLEN); 247 248 ev->type = LLC_SAP_EV_TYPE_PRIM; 249 ev->prim = LLC_XID_PRIM; 250 ev->prim_type = LLC_PRIM_TYPE_REQ; 251 llc_sap_state_process(sap, skb); 252} 253 254/** 255 * llc_sap_rcv - sends received pdus to the sap state machine 256 * @sap: current sap component structure. 257 * @skb: received frame. 258 * 259 * Sends received pdus to the sap state machine. 260 */ 261static void llc_sap_rcv(struct llc_sap *sap, struct sk_buff *skb) 262{ 263 struct llc_sap_state_ev *ev = llc_sap_ev(skb); 264 265 ev->type = LLC_SAP_EV_TYPE_PDU; 266 ev->reason = 0; 267 llc_sap_state_process(sap, skb); 268} 269 270/** 271 * llc_lookup_dgram - Finds dgram socket for the local sap/mac 272 * @sap: SAP 273 * @laddr: address of local LLC (MAC + SAP) 274 * 275 * Search socket list of the SAP and finds connection using the local 276 * mac, and local sap. Returns pointer for socket found, %NULL otherwise. 277 */ 278static struct sock *llc_lookup_dgram(struct llc_sap *sap, 279 struct llc_addr *laddr) 280{ 281 struct sock *rc; 282 struct hlist_node *node; 283 284 read_lock_bh(&sap->sk_list.lock); 285 sk_for_each(rc, node, &sap->sk_list.list) { 286 struct llc_sock *llc = llc_sk(rc); 287 288 if (rc->sk_type == SOCK_DGRAM && 289 llc->laddr.lsap == laddr->lsap && 290 llc_mac_match(llc->laddr.mac, laddr->mac)) { 291 sock_hold(rc); 292 goto found; 293 } 294 } 295 rc = NULL; 296found: 297 read_unlock_bh(&sap->sk_list.lock); 298 return rc; 299} 300 301void llc_sap_handler(struct llc_sap *sap, struct sk_buff *skb) 302{ 303 struct llc_addr laddr; 304 struct sock *sk; 305 306 llc_pdu_decode_da(skb, laddr.mac); 307 llc_pdu_decode_dsap(skb, &laddr.lsap); 308 309 sk = llc_lookup_dgram(sap, &laddr); 310 if (sk) { 311 skb->sk = sk; 312 llc_sap_rcv(sap, skb); 313 sock_put(sk); 314 } else 315 kfree_skb(skb); 316} 317