1/* 2 * X.25 Packet Layer release 002 3 * 4 * This is ALPHA test software. This code may break your machine, 5 * randomly fail to work with new releases, misbehave and/or generally 6 * screw up. It might even work. 7 * 8 * This code REQUIRES 2.1.15 or higher 9 * 10 * This module: 11 * This module is free software; you can redistribute it and/or 12 * modify it under the terms of the GNU General Public License 13 * as published by the Free Software Foundation; either version 14 * 2 of the License, or (at your option) any later version. 15 * 16 * History 17 * X.25 001 Jonathan Naylor Started coding. 18 * X.25 002 Jonathan Naylor Centralised disconnection processing. 19 * mar/20/00 Daniela Squassoni Disabling/enabling of facilities 20 * negotiation. 21 * jun/24/01 Arnaldo C. Melo use skb_queue_purge, cleanups 22 * apr/04/15 Shaun Pereira Fast select with no 23 * restriction on response. 24 */ 25 26#include <linux/kernel.h> 27#include <linux/string.h> 28#include <linux/skbuff.h> 29#include <net/sock.h> 30#include <net/tcp_states.h> 31#include <net/x25.h> 32 33/* 34 * This routine purges all of the queues of frames. 35 */ 36void x25_clear_queues(struct sock *sk) 37{ 38 struct x25_sock *x25 = x25_sk(sk); 39 40 skb_queue_purge(&sk->sk_write_queue); 41 skb_queue_purge(&x25->ack_queue); 42 skb_queue_purge(&x25->interrupt_in_queue); 43 skb_queue_purge(&x25->interrupt_out_queue); 44 skb_queue_purge(&x25->fragment_queue); 45} 46 47 48/* 49 * This routine purges the input queue of those frames that have been 50 * acknowledged. This replaces the boxes labelled "V(a) <- N(r)" on the 51 * SDL diagram. 52*/ 53void x25_frames_acked(struct sock *sk, unsigned short nr) 54{ 55 struct sk_buff *skb; 56 struct x25_sock *x25 = x25_sk(sk); 57 int modulus = x25->neighbour->extended ? X25_EMODULUS : X25_SMODULUS; 58 59 /* 60 * Remove all the ack-ed frames from the ack queue. 61 */ 62 if (x25->va != nr) 63 while (skb_peek(&x25->ack_queue) && x25->va != nr) { 64 skb = skb_dequeue(&x25->ack_queue); 65 kfree_skb(skb); 66 x25->va = (x25->va + 1) % modulus; 67 } 68} 69 70void x25_requeue_frames(struct sock *sk) 71{ 72 struct sk_buff *skb, *skb_prev = NULL; 73 74 /* 75 * Requeue all the un-ack-ed frames on the output queue to be picked 76 * up by x25_kick. This arrangement handles the possibility of an empty 77 * output queue. 78 */ 79 while ((skb = skb_dequeue(&x25_sk(sk)->ack_queue)) != NULL) { 80 if (!skb_prev) 81 skb_queue_head(&sk->sk_write_queue, skb); 82 else 83 skb_append(skb_prev, skb, &sk->sk_write_queue); 84 skb_prev = skb; 85 } 86} 87 88/* 89 * Validate that the value of nr is between va and vs. Return true or 90 * false for testing. 91 */ 92int x25_validate_nr(struct sock *sk, unsigned short nr) 93{ 94 struct x25_sock *x25 = x25_sk(sk); 95 unsigned short vc = x25->va; 96 int modulus = x25->neighbour->extended ? X25_EMODULUS : X25_SMODULUS; 97 98 while (vc != x25->vs) { 99 if (nr == vc) 100 return 1; 101 vc = (vc + 1) % modulus; 102 } 103 104 return nr == x25->vs ? 1 : 0; 105} 106 107/* 108 * This routine is called when the packet layer internally generates a 109 * control frame. 110 */ 111void x25_write_internal(struct sock *sk, int frametype) 112{ 113 struct x25_sock *x25 = x25_sk(sk); 114 struct sk_buff *skb; 115 unsigned char *dptr; 116 unsigned char facilities[X25_MAX_FAC_LEN]; 117 unsigned char addresses[1 + X25_ADDR_LEN]; 118 unsigned char lci1, lci2; 119 /* 120 * Default safe frame size. 121 */ 122 int len = X25_MAX_L2_LEN + X25_EXT_MIN_LEN; 123 124 /* 125 * Adjust frame size. 126 */ 127 switch (frametype) { 128 case X25_CALL_REQUEST: 129 len += 1 + X25_ADDR_LEN + X25_MAX_FAC_LEN + 130 X25_MAX_CUD_LEN; 131 break; 132 case X25_CALL_ACCEPTED: /* fast sel with no restr on resp */ 133 if(x25->facilities.reverse & 0x80) { 134 len += 1 + X25_MAX_FAC_LEN + X25_MAX_CUD_LEN; 135 } else { 136 len += 1 + X25_MAX_FAC_LEN; 137 } 138 break; 139 case X25_CLEAR_REQUEST: 140 case X25_RESET_REQUEST: 141 len += 2; 142 break; 143 case X25_RR: 144 case X25_RNR: 145 case X25_REJ: 146 case X25_CLEAR_CONFIRMATION: 147 case X25_INTERRUPT_CONFIRMATION: 148 case X25_RESET_CONFIRMATION: 149 break; 150 default: 151 printk(KERN_ERR "X.25: invalid frame type %02X\n", 152 frametype); 153 return; 154 } 155 156 if ((skb = alloc_skb(len, GFP_ATOMIC)) == NULL) 157 return; 158 159 /* 160 * Space for Ethernet and 802.2 LLC headers. 161 */ 162 skb_reserve(skb, X25_MAX_L2_LEN); 163 164 /* 165 * Make space for the GFI and LCI, and fill them in. 166 */ 167 dptr = skb_put(skb, 2); 168 169 lci1 = (x25->lci >> 8) & 0x0F; 170 lci2 = (x25->lci >> 0) & 0xFF; 171 172 if (x25->neighbour->extended) { 173 *dptr++ = lci1 | X25_GFI_EXTSEQ; 174 *dptr++ = lci2; 175 } else { 176 *dptr++ = lci1 | X25_GFI_STDSEQ; 177 *dptr++ = lci2; 178 } 179 180 /* 181 * Now fill in the frame type specific information. 182 */ 183 switch (frametype) { 184 185 case X25_CALL_REQUEST: 186 dptr = skb_put(skb, 1); 187 *dptr++ = X25_CALL_REQUEST; 188 len = x25_addr_aton(addresses, &x25->dest_addr, 189 &x25->source_addr); 190 dptr = skb_put(skb, len); 191 memcpy(dptr, addresses, len); 192 len = x25_create_facilities(facilities, 193 &x25->facilities, 194 &x25->dte_facilities, 195 x25->neighbour->global_facil_mask); 196 dptr = skb_put(skb, len); 197 memcpy(dptr, facilities, len); 198 dptr = skb_put(skb, x25->calluserdata.cudlength); 199 memcpy(dptr, x25->calluserdata.cuddata, 200 x25->calluserdata.cudlength); 201 x25->calluserdata.cudlength = 0; 202 break; 203 204 case X25_CALL_ACCEPTED: 205 dptr = skb_put(skb, 2); 206 *dptr++ = X25_CALL_ACCEPTED; 207 *dptr++ = 0x00; /* Address lengths */ 208 len = x25_create_facilities(facilities, 209 &x25->facilities, 210 &x25->dte_facilities, 211 x25->vc_facil_mask); 212 dptr = skb_put(skb, len); 213 memcpy(dptr, facilities, len); 214 215 /* fast select with no restriction on response 216 allows call user data. Userland must 217 ensure it is ours and not theirs */ 218 if(x25->facilities.reverse & 0x80) { 219 dptr = skb_put(skb, 220 x25->calluserdata.cudlength); 221 memcpy(dptr, x25->calluserdata.cuddata, 222 x25->calluserdata.cudlength); 223 } 224 x25->calluserdata.cudlength = 0; 225 break; 226 227 case X25_CLEAR_REQUEST: 228 case X25_RESET_REQUEST: 229 dptr = skb_put(skb, 3); 230 *dptr++ = frametype; 231 *dptr++ = 0x00; 232 *dptr++ = 0x00; 233 break; 234 235 case X25_RR: 236 case X25_RNR: 237 case X25_REJ: 238 if (x25->neighbour->extended) { 239 dptr = skb_put(skb, 2); 240 *dptr++ = frametype; 241 *dptr++ = (x25->vr << 1) & 0xFE; 242 } else { 243 dptr = skb_put(skb, 1); 244 *dptr = frametype; 245 *dptr++ |= (x25->vr << 5) & 0xE0; 246 } 247 break; 248 249 case X25_CLEAR_CONFIRMATION: 250 case X25_INTERRUPT_CONFIRMATION: 251 case X25_RESET_CONFIRMATION: 252 dptr = skb_put(skb, 1); 253 *dptr = frametype; 254 break; 255 } 256 257 x25_transmit_link(skb, x25->neighbour); 258} 259 260/* 261 * Unpick the contents of the passed X.25 Packet Layer frame. 262 */ 263int x25_decode(struct sock *sk, struct sk_buff *skb, int *ns, int *nr, int *q, 264 int *d, int *m) 265{ 266 struct x25_sock *x25 = x25_sk(sk); 267 unsigned char *frame = skb->data; 268 269 *ns = *nr = *q = *d = *m = 0; 270 271 switch (frame[2]) { 272 case X25_CALL_REQUEST: 273 case X25_CALL_ACCEPTED: 274 case X25_CLEAR_REQUEST: 275 case X25_CLEAR_CONFIRMATION: 276 case X25_INTERRUPT: 277 case X25_INTERRUPT_CONFIRMATION: 278 case X25_RESET_REQUEST: 279 case X25_RESET_CONFIRMATION: 280 case X25_RESTART_REQUEST: 281 case X25_RESTART_CONFIRMATION: 282 case X25_REGISTRATION_REQUEST: 283 case X25_REGISTRATION_CONFIRMATION: 284 case X25_DIAGNOSTIC: 285 return frame[2]; 286 } 287 288 if (x25->neighbour->extended) { 289 if (frame[2] == X25_RR || 290 frame[2] == X25_RNR || 291 frame[2] == X25_REJ) { 292 *nr = (frame[3] >> 1) & 0x7F; 293 return frame[2]; 294 } 295 } else { 296 if ((frame[2] & 0x1F) == X25_RR || 297 (frame[2] & 0x1F) == X25_RNR || 298 (frame[2] & 0x1F) == X25_REJ) { 299 *nr = (frame[2] >> 5) & 0x07; 300 return frame[2] & 0x1F; 301 } 302 } 303 304 if (x25->neighbour->extended) { 305 if ((frame[2] & 0x01) == X25_DATA) { 306 *q = (frame[0] & X25_Q_BIT) == X25_Q_BIT; 307 *d = (frame[0] & X25_D_BIT) == X25_D_BIT; 308 *m = (frame[3] & X25_EXT_M_BIT) == X25_EXT_M_BIT; 309 *nr = (frame[3] >> 1) & 0x7F; 310 *ns = (frame[2] >> 1) & 0x7F; 311 return X25_DATA; 312 } 313 } else { 314 if ((frame[2] & 0x01) == X25_DATA) { 315 *q = (frame[0] & X25_Q_BIT) == X25_Q_BIT; 316 *d = (frame[0] & X25_D_BIT) == X25_D_BIT; 317 *m = (frame[2] & X25_STD_M_BIT) == X25_STD_M_BIT; 318 *nr = (frame[2] >> 5) & 0x07; 319 *ns = (frame[2] >> 1) & 0x07; 320 return X25_DATA; 321 } 322 } 323 324 printk(KERN_DEBUG "X.25: invalid PLP frame %02X %02X %02X\n", 325 frame[0], frame[1], frame[2]); 326 327 return X25_ILLEGAL; 328} 329 330void x25_disconnect(struct sock *sk, int reason, unsigned char cause, 331 unsigned char diagnostic) 332{ 333 struct x25_sock *x25 = x25_sk(sk); 334 335 x25_clear_queues(sk); 336 x25_stop_timer(sk); 337 338 x25->lci = 0; 339 x25->state = X25_STATE_0; 340 341 x25->causediag.cause = cause; 342 x25->causediag.diagnostic = diagnostic; 343 344 sk->sk_state = TCP_CLOSE; 345 sk->sk_err = reason; 346 sk->sk_shutdown |= SEND_SHUTDOWN; 347 348 if (!sock_flag(sk, SOCK_DEAD)) { 349 sk->sk_state_change(sk); 350 sock_set_flag(sk, SOCK_DEAD); 351 } 352} 353 354/* 355 * Clear an own-rx-busy condition and tell the peer about this, provided 356 * that there is a significant amount of free receive buffer space available. 357 */ 358void x25_check_rbuf(struct sock *sk) 359{ 360 struct x25_sock *x25 = x25_sk(sk); 361 362 if (atomic_read(&sk->sk_rmem_alloc) < (sk->sk_rcvbuf / 2) && 363 (x25->condition & X25_COND_OWN_RX_BUSY)) { 364 x25->condition &= ~X25_COND_OWN_RX_BUSY; 365 x25->condition &= ~X25_COND_ACK_PENDING; 366 x25->vl = x25->vr; 367 x25_write_internal(sk, X25_RR); 368 x25_stop_timer(sk); 369 } 370} 371