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/slab.h> 27#include <linux/kernel.h> 28#include <linux/string.h> 29#include <linux/skbuff.h> 30#include <net/sock.h> 31#include <net/tcp_states.h> 32#include <net/x25.h> 33 34/* 35 * This routine purges all of the queues of frames. 36 */ 37void x25_clear_queues(struct sock *sk) 38{ 39 struct x25_sock *x25 = x25_sk(sk); 40 41 skb_queue_purge(&sk->sk_write_queue); 42 skb_queue_purge(&x25->ack_queue); 43 skb_queue_purge(&x25->interrupt_in_queue); 44 skb_queue_purge(&x25->interrupt_out_queue); 45 skb_queue_purge(&x25->fragment_queue); 46} 47 48 49/* 50 * This routine purges the input queue of those frames that have been 51 * acknowledged. This replaces the boxes labelled "V(a) <- N(r)" on the 52 * SDL diagram. 53*/ 54void x25_frames_acked(struct sock *sk, unsigned short nr) 55{ 56 struct sk_buff *skb; 57 struct x25_sock *x25 = x25_sk(sk); 58 int modulus = x25->neighbour->extended ? X25_EMODULUS : X25_SMODULUS; 59 60 /* 61 * Remove all the ack-ed frames from the ack queue. 62 */ 63 if (x25->va != nr) 64 while (skb_peek(&x25->ack_queue) && x25->va != nr) { 65 skb = skb_dequeue(&x25->ack_queue); 66 kfree_skb(skb); 67 x25->va = (x25->va + 1) % modulus; 68 } 69} 70 71void x25_requeue_frames(struct sock *sk) 72{ 73 struct sk_buff *skb, *skb_prev = NULL; 74 75 /* 76 * Requeue all the un-ack-ed frames on the output queue to be picked 77 * up by x25_kick. This arrangement handles the possibility of an empty 78 * output queue. 79 */ 80 while ((skb = skb_dequeue(&x25_sk(sk)->ack_queue)) != NULL) { 81 if (!skb_prev) 82 skb_queue_head(&sk->sk_write_queue, skb); 83 else 84 skb_append(skb_prev, skb, &sk->sk_write_queue); 85 skb_prev = skb; 86 } 87} 88 89/* 90 * Validate that the value of nr is between va and vs. Return true or 91 * false for testing. 92 */ 93int x25_validate_nr(struct sock *sk, unsigned short nr) 94{ 95 struct x25_sock *x25 = x25_sk(sk); 96 unsigned short vc = x25->va; 97 int modulus = x25->neighbour->extended ? X25_EMODULUS : X25_SMODULUS; 98 99 while (vc != x25->vs) { 100 if (nr == vc) 101 return 1; 102 vc = (vc + 1) % modulus; 103 } 104 105 return nr == x25->vs ? 1 : 0; 106} 107 108/* 109 * This routine is called when the packet layer internally generates a 110 * control frame. 111 */ 112void x25_write_internal(struct sock *sk, int frametype) 113{ 114 struct x25_sock *x25 = x25_sk(sk); 115 struct sk_buff *skb; 116 unsigned char *dptr; 117 unsigned char facilities[X25_MAX_FAC_LEN]; 118 unsigned char addresses[1 + X25_ADDR_LEN]; 119 unsigned char lci1, lci2; 120 /* 121 * Default safe frame size. 122 */ 123 int len = X25_MAX_L2_LEN + X25_EXT_MIN_LEN; 124 125 /* 126 * Adjust frame size. 127 */ 128 switch (frametype) { 129 case X25_CALL_REQUEST: 130 len += 1 + X25_ADDR_LEN + X25_MAX_FAC_LEN + 131 X25_MAX_CUD_LEN; 132 break; 133 case X25_CALL_ACCEPTED: /* fast sel with no restr on resp */ 134 if(x25->facilities.reverse & 0x80) { 135 len += 1 + X25_MAX_FAC_LEN + X25_MAX_CUD_LEN; 136 } else { 137 len += 1 + X25_MAX_FAC_LEN; 138 } 139 break; 140 case X25_CLEAR_REQUEST: 141 case X25_RESET_REQUEST: 142 len += 2; 143 break; 144 case X25_RR: 145 case X25_RNR: 146 case X25_REJ: 147 case X25_CLEAR_CONFIRMATION: 148 case X25_INTERRUPT_CONFIRMATION: 149 case X25_RESET_CONFIRMATION: 150 break; 151 default: 152 printk(KERN_ERR "X.25: invalid frame type %02X\n", 153 frametype); 154 return; 155 } 156 157 if ((skb = alloc_skb(len, GFP_ATOMIC)) == NULL) 158 return; 159 160 /* 161 * Space for Ethernet and 802.2 LLC headers. 162 */ 163 skb_reserve(skb, X25_MAX_L2_LEN); 164 165 /* 166 * Make space for the GFI and LCI, and fill them in. 167 */ 168 dptr = skb_put(skb, 2); 169 170 lci1 = (x25->lci >> 8) & 0x0F; 171 lci2 = (x25->lci >> 0) & 0xFF; 172 173 if (x25->neighbour->extended) { 174 *dptr++ = lci1 | X25_GFI_EXTSEQ; 175 *dptr++ = lci2; 176 } else { 177 *dptr++ = lci1 | X25_GFI_STDSEQ; 178 *dptr++ = lci2; 179 } 180 181 /* 182 * Now fill in the frame type specific information. 183 */ 184 switch (frametype) { 185 186 case X25_CALL_REQUEST: 187 dptr = skb_put(skb, 1); 188 *dptr++ = X25_CALL_REQUEST; 189 len = x25_addr_aton(addresses, &x25->dest_addr, 190 &x25->source_addr); 191 dptr = skb_put(skb, len); 192 memcpy(dptr, addresses, len); 193 len = x25_create_facilities(facilities, 194 &x25->facilities, 195 &x25->dte_facilities, 196 x25->neighbour->global_facil_mask); 197 dptr = skb_put(skb, len); 198 memcpy(dptr, facilities, len); 199 dptr = skb_put(skb, x25->calluserdata.cudlength); 200 memcpy(dptr, x25->calluserdata.cuddata, 201 x25->calluserdata.cudlength); 202 x25->calluserdata.cudlength = 0; 203 break; 204 205 case X25_CALL_ACCEPTED: 206 dptr = skb_put(skb, 2); 207 *dptr++ = X25_CALL_ACCEPTED; 208 *dptr++ = 0x00; /* Address lengths */ 209 len = x25_create_facilities(facilities, 210 &x25->facilities, 211 &x25->dte_facilities, 212 x25->vc_facil_mask); 213 dptr = skb_put(skb, len); 214 memcpy(dptr, facilities, len); 215 216 /* fast select with no restriction on response 217 allows call user data. Userland must 218 ensure it is ours and not theirs */ 219 if(x25->facilities.reverse & 0x80) { 220 dptr = skb_put(skb, 221 x25->calluserdata.cudlength); 222 memcpy(dptr, x25->calluserdata.cuddata, 223 x25->calluserdata.cudlength); 224 } 225 x25->calluserdata.cudlength = 0; 226 break; 227 228 case X25_CLEAR_REQUEST: 229 dptr = skb_put(skb, 3); 230 *dptr++ = frametype; 231 *dptr++ = x25->causediag.cause; 232 *dptr++ = x25->causediag.diagnostic; 233 break; 234 235 case X25_RESET_REQUEST: 236 dptr = skb_put(skb, 3); 237 *dptr++ = frametype; 238 *dptr++ = 0x00; 239 *dptr++ = 0x00; 240 break; 241 242 case X25_RR: 243 case X25_RNR: 244 case X25_REJ: 245 if (x25->neighbour->extended) { 246 dptr = skb_put(skb, 2); 247 *dptr++ = frametype; 248 *dptr++ = (x25->vr << 1) & 0xFE; 249 } else { 250 dptr = skb_put(skb, 1); 251 *dptr = frametype; 252 *dptr++ |= (x25->vr << 5) & 0xE0; 253 } 254 break; 255 256 case X25_CLEAR_CONFIRMATION: 257 case X25_INTERRUPT_CONFIRMATION: 258 case X25_RESET_CONFIRMATION: 259 dptr = skb_put(skb, 1); 260 *dptr = frametype; 261 break; 262 } 263 264 x25_transmit_link(skb, x25->neighbour); 265} 266 267/* 268 * Unpick the contents of the passed X.25 Packet Layer frame. 269 */ 270int x25_decode(struct sock *sk, struct sk_buff *skb, int *ns, int *nr, int *q, 271 int *d, int *m) 272{ 273 struct x25_sock *x25 = x25_sk(sk); 274 unsigned char *frame = skb->data; 275 276 *ns = *nr = *q = *d = *m = 0; 277 278 switch (frame[2]) { 279 case X25_CALL_REQUEST: 280 case X25_CALL_ACCEPTED: 281 case X25_CLEAR_REQUEST: 282 case X25_CLEAR_CONFIRMATION: 283 case X25_INTERRUPT: 284 case X25_INTERRUPT_CONFIRMATION: 285 case X25_RESET_REQUEST: 286 case X25_RESET_CONFIRMATION: 287 case X25_RESTART_REQUEST: 288 case X25_RESTART_CONFIRMATION: 289 case X25_REGISTRATION_REQUEST: 290 case X25_REGISTRATION_CONFIRMATION: 291 case X25_DIAGNOSTIC: 292 return frame[2]; 293 } 294 295 if (x25->neighbour->extended) { 296 if (frame[2] == X25_RR || 297 frame[2] == X25_RNR || 298 frame[2] == X25_REJ) { 299 *nr = (frame[3] >> 1) & 0x7F; 300 return frame[2]; 301 } 302 } else { 303 if ((frame[2] & 0x1F) == X25_RR || 304 (frame[2] & 0x1F) == X25_RNR || 305 (frame[2] & 0x1F) == X25_REJ) { 306 *nr = (frame[2] >> 5) & 0x07; 307 return frame[2] & 0x1F; 308 } 309 } 310 311 if (x25->neighbour->extended) { 312 if ((frame[2] & 0x01) == X25_DATA) { 313 *q = (frame[0] & X25_Q_BIT) == X25_Q_BIT; 314 *d = (frame[0] & X25_D_BIT) == X25_D_BIT; 315 *m = (frame[3] & X25_EXT_M_BIT) == X25_EXT_M_BIT; 316 *nr = (frame[3] >> 1) & 0x7F; 317 *ns = (frame[2] >> 1) & 0x7F; 318 return X25_DATA; 319 } 320 } else { 321 if ((frame[2] & 0x01) == X25_DATA) { 322 *q = (frame[0] & X25_Q_BIT) == X25_Q_BIT; 323 *d = (frame[0] & X25_D_BIT) == X25_D_BIT; 324 *m = (frame[2] & X25_STD_M_BIT) == X25_STD_M_BIT; 325 *nr = (frame[2] >> 5) & 0x07; 326 *ns = (frame[2] >> 1) & 0x07; 327 return X25_DATA; 328 } 329 } 330 331 printk(KERN_DEBUG "X.25: invalid PLP frame %02X %02X %02X\n", 332 frame[0], frame[1], frame[2]); 333 334 return X25_ILLEGAL; 335} 336 337void x25_disconnect(struct sock *sk, int reason, unsigned char cause, 338 unsigned char diagnostic) 339{ 340 struct x25_sock *x25 = x25_sk(sk); 341 342 x25_clear_queues(sk); 343 x25_stop_timer(sk); 344 345 x25->lci = 0; 346 x25->state = X25_STATE_0; 347 348 x25->causediag.cause = cause; 349 x25->causediag.diagnostic = diagnostic; 350 351 sk->sk_state = TCP_CLOSE; 352 sk->sk_err = reason; 353 sk->sk_shutdown |= SEND_SHUTDOWN; 354 355 if (!sock_flag(sk, SOCK_DEAD)) { 356 sk->sk_state_change(sk); 357 sock_set_flag(sk, SOCK_DEAD); 358 } 359} 360 361/* 362 * Clear an own-rx-busy condition and tell the peer about this, provided 363 * that there is a significant amount of free receive buffer space available. 364 */ 365void x25_check_rbuf(struct sock *sk) 366{ 367 struct x25_sock *x25 = x25_sk(sk); 368 369 if (atomic_read(&sk->sk_rmem_alloc) < (sk->sk_rcvbuf >> 1) && 370 (x25->condition & X25_COND_OWN_RX_BUSY)) { 371 x25->condition &= ~X25_COND_OWN_RX_BUSY; 372 x25->condition &= ~X25_COND_ACK_PENDING; 373 x25->vl = x25->vr; 374 x25_write_internal(sk, X25_RR); 375 x25_stop_timer(sk); 376 } 377} 378