1 /* 2 * This program is free software; you can redistribute it and/or modify 3 * it under the terms of the GNU General Public License as published by 4 * the Free Software Foundation; either version 2 of the License, or 5 * (at your option) any later version. 6 * 7 * Copyright (C) Alan Cox GW4PTS (alan@lxorguk.ukuu.org.uk) 8 * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk) 9 * Copyright (C) Joerg Reuter DL1BKE (jreuter@yaina.de) 10 */ 11 #include <linux/config.h> 12 #include <linux/errno.h> 13 #include <linux/types.h> 14 #include <linux/socket.h> 15 #include <linux/in.h> 16 #include <linux/kernel.h> 17 #include <linux/module.h> 18 #include <linux/sched.h> 19 #include <linux/timer.h> 20 #include <linux/string.h> 21 #include <linux/sockios.h> 22 #include <linux/spinlock.h> 23 #include <linux/net.h> 24 #include <net/ax25.h> 25 #include <linux/inet.h> 26 #include <linux/netdevice.h> 27 #include <linux/skbuff.h> 28 #include <linux/netfilter.h> 29 #include <net/sock.h> 30 #include <asm/uaccess.h> 31 #include <asm/system.h> 32 #include <linux/fcntl.h> 33 #include <linux/mm.h> 34 #include <linux/interrupt.h> 35 36 static DEFINE_SPINLOCK(ax25_frag_lock); 37 38 ax25_cb *ax25_send_frame(struct sk_buff *skb, int paclen, ax25_address *src, ax25_address *dest, ax25_digi *digi, struct net_device *dev) 39 { 40 ax25_dev *ax25_dev; 41 ax25_cb *ax25; 42 43 /* 44 * Take the default packet length for the device if zero is 45 * specified. 46 */ 47 if (paclen == 0) { 48 if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL) 49 return NULL; 50 51 paclen = ax25_dev->values[AX25_VALUES_PACLEN]; 52 } 53 54 /* 55 * Look for an existing connection. 56 */ 57 if ((ax25 = ax25_find_cb(src, dest, digi, dev)) != NULL) { 58 ax25_output(ax25, paclen, skb); 59 return ax25; /* It already existed */ 60 } 61 62 if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL) 63 return NULL; 64 65 if ((ax25 = ax25_create_cb()) == NULL) 66 return NULL; 67 68 ax25_fillin_cb(ax25, ax25_dev); 69 70 ax25->source_addr = *src; 71 ax25->dest_addr = *dest; 72 73 if (digi != NULL) { 74 if ((ax25->digipeat = kmalloc(sizeof(ax25_digi), GFP_ATOMIC)) == NULL) { 75 ax25_cb_put(ax25); 76 return NULL; 77 } 78 memcpy(ax25->digipeat, digi, sizeof(ax25_digi)); 79 } 80 81 switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) { 82 case AX25_PROTO_STD_SIMPLEX: 83 case AX25_PROTO_STD_DUPLEX: 84 ax25_std_establish_data_link(ax25); 85 break; 86 87 #ifdef CONFIG_AX25_DAMA_SLAVE 88 case AX25_PROTO_DAMA_SLAVE: 89 if (ax25_dev->dama.slave) 90 ax25_ds_establish_data_link(ax25); 91 else 92 ax25_std_establish_data_link(ax25); 93 break; 94 #endif 95 } 96 97 ax25_cb_add(ax25); 98 99 ax25->state = AX25_STATE_1; 100 101 ax25_start_heartbeat(ax25); 102 103 ax25_output(ax25, paclen, skb); 104 105 return ax25; /* We had to create it */ 106 } 107 108 EXPORT_SYMBOL(ax25_send_frame); 109 110 /* 111 * All outgoing AX.25 I frames pass via this routine. Therefore this is 112 * where the fragmentation of frames takes place. If fragment is set to 113 * zero then we are not allowed to do fragmentation, even if the frame 114 * is too large. 115 */ 116 void ax25_output(ax25_cb *ax25, int paclen, struct sk_buff *skb) 117 { 118 struct sk_buff *skbn; 119 unsigned char *p; 120 int frontlen, len, fragno, ka9qfrag, first = 1; 121 122 if ((skb->len - 1) > paclen) { 123 if (*skb->data == AX25_P_TEXT) { 124 skb_pull(skb, 1); /* skip PID */ 125 ka9qfrag = 0; 126 } else { 127 paclen -= 2; /* Allow for fragment control info */ 128 ka9qfrag = 1; 129 } 130 131 fragno = skb->len / paclen; 132 if (skb->len % paclen == 0) fragno--; 133 134 frontlen = skb_headroom(skb); /* Address space + CTRL */ 135 136 while (skb->len > 0) { 137 spin_lock_bh(&ax25_frag_lock); 138 if ((skbn = alloc_skb(paclen + 2 + frontlen, GFP_ATOMIC)) == NULL) { 139 spin_unlock_bh(&ax25_frag_lock); 140 printk(KERN_CRIT "AX.25: ax25_output - out of memory\n"); 141 return; 142 } 143 144 if (skb->sk != NULL) 145 skb_set_owner_w(skbn, skb->sk); 146 147 spin_unlock_bh(&ax25_frag_lock); 148 149 len = (paclen > skb->len) ? skb->len : paclen; 150 151 if (ka9qfrag == 1) { 152 skb_reserve(skbn, frontlen + 2); 153 skbn->nh.raw = skbn->data + (skb->nh.raw - skb->data); 154 memcpy(skb_put(skbn, len), skb->data, len); 155 p = skb_push(skbn, 2); 156 157 *p++ = AX25_P_SEGMENT; 158 159 *p = fragno--; 160 if (first) { 161 *p |= AX25_SEG_FIRST; 162 first = 0; 163 } 164 } else { 165 skb_reserve(skbn, frontlen + 1); 166 skbn->nh.raw = skbn->data + (skb->nh.raw - skb->data); 167 memcpy(skb_put(skbn, len), skb->data, len); 168 p = skb_push(skbn, 1); 169 *p = AX25_P_TEXT; 170 } 171 172 skb_pull(skb, len); 173 skb_queue_tail(&ax25->write_queue, skbn); /* Throw it on the queue */ 174 } 175 176 kfree_skb(skb); 177 } else { 178 skb_queue_tail(&ax25->write_queue, skb); /* Throw it on the queue */ 179 } 180 181 switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) { 182 case AX25_PROTO_STD_SIMPLEX: 183 case AX25_PROTO_STD_DUPLEX: 184 ax25_kick(ax25); 185 break; 186 187 #ifdef CONFIG_AX25_DAMA_SLAVE 188 /* 189 * A DAMA slave is _required_ to work as normal AX.25L2V2 190 * if no DAMA master is available. 191 */ 192 case AX25_PROTO_DAMA_SLAVE: 193 if (!ax25->ax25_dev->dama.slave) ax25_kick(ax25); 194 break; 195 #endif 196 } 197 } 198 199 /* 200 * This procedure is passed a buffer descriptor for an iframe. It builds 201 * the rest of the control part of the frame and then writes it out. 202 */ 203 static void ax25_send_iframe(ax25_cb *ax25, struct sk_buff *skb, int poll_bit) 204 { 205 unsigned char *frame; 206 207 if (skb == NULL) 208 return; 209 210 skb->nh.raw = skb->data; 211 212 if (ax25->modulus == AX25_MODULUS) { 213 frame = skb_push(skb, 1); 214 215 *frame = AX25_I; 216 *frame |= (poll_bit) ? AX25_PF : 0; 217 *frame |= (ax25->vr << 5); 218 *frame |= (ax25->vs << 1); 219 } else { 220 frame = skb_push(skb, 2); 221 222 frame[0] = AX25_I; 223 frame[0] |= (ax25->vs << 1); 224 frame[1] = (poll_bit) ? AX25_EPF : 0; 225 frame[1] |= (ax25->vr << 1); 226 } 227 228 ax25_start_idletimer(ax25); 229 230 ax25_transmit_buffer(ax25, skb, AX25_COMMAND); 231 } 232 233 void ax25_kick(ax25_cb *ax25) 234 { 235 struct sk_buff *skb, *skbn; 236 int last = 1; 237 unsigned short start, end, next; 238 239 if (ax25->state != AX25_STATE_3 && ax25->state != AX25_STATE_4) 240 return; 241 242 if (ax25->condition & AX25_COND_PEER_RX_BUSY) 243 return; 244 245 if (skb_peek(&ax25->write_queue) == NULL) 246 return; 247 248 start = (skb_peek(&ax25->ack_queue) == NULL) ? ax25->va : ax25->vs; 249 end = (ax25->va + ax25->window) % ax25->modulus; 250 251 if (start == end) 252 return; 253 254 ax25->vs = start; 255 256 /* 257 * Transmit data until either we're out of data to send or 258 * the window is full. Send a poll on the final I frame if 259 * the window is filled. 260 */ 261 262 /* 263 * Dequeue the frame and copy it. 264 */ 265 skb = skb_dequeue(&ax25->write_queue); 266 267 do { 268 if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) { 269 skb_queue_head(&ax25->write_queue, skb); 270 break; 271 } 272 273 if (skb->sk != NULL) 274 skb_set_owner_w(skbn, skb->sk); 275 276 next = (ax25->vs + 1) % ax25->modulus; 277 last = (next == end); 278 279 /* 280 * Transmit the frame copy. 281 * bke 960114: do not set the Poll bit on the last frame 282 * in DAMA mode. 283 */ 284 switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) { 285 case AX25_PROTO_STD_SIMPLEX: 286 case AX25_PROTO_STD_DUPLEX: 287 ax25_send_iframe(ax25, skbn, (last) ? AX25_POLLON : AX25_POLLOFF); 288 break; 289 290 #ifdef CONFIG_AX25_DAMA_SLAVE 291 case AX25_PROTO_DAMA_SLAVE: 292 ax25_send_iframe(ax25, skbn, AX25_POLLOFF); 293 break; 294 #endif 295 } 296 297 ax25->vs = next; 298 299 /* 300 * Requeue the original data frame. 301 */ 302 skb_queue_tail(&ax25->ack_queue, skb); 303 304 } while (!last && (skb = skb_dequeue(&ax25->write_queue)) != NULL); 305 306 ax25->condition &= ~AX25_COND_ACK_PENDING; 307 308 if (!ax25_t1timer_running(ax25)) { 309 ax25_stop_t3timer(ax25); 310 ax25_calculate_t1(ax25); 311 ax25_start_t1timer(ax25); 312 } 313 } 314 315 void ax25_transmit_buffer(ax25_cb *ax25, struct sk_buff *skb, int type) 316 { 317 struct sk_buff *skbn; 318 unsigned char *ptr; 319 int headroom; 320 321 if (ax25->ax25_dev == NULL) { 322 ax25_disconnect(ax25, ENETUNREACH); 323 return; 324 } 325 326 headroom = ax25_addr_size(ax25->digipeat); 327 328 if (skb_headroom(skb) < headroom) { 329 if ((skbn = skb_realloc_headroom(skb, headroom)) == NULL) { 330 printk(KERN_CRIT "AX.25: ax25_transmit_buffer - out of memory\n"); 331 kfree_skb(skb); 332 return; 333 } 334 335 if (skb->sk != NULL) 336 skb_set_owner_w(skbn, skb->sk); 337 338 kfree_skb(skb); 339 skb = skbn; 340 } 341 342 ptr = skb_push(skb, headroom); 343 344 ax25_addr_build(ptr, &ax25->source_addr, &ax25->dest_addr, ax25->digipeat, type, ax25->modulus); 345 346 ax25_queue_xmit(skb, ax25->ax25_dev->dev); 347 } 348 349 /* 350 * A small shim to dev_queue_xmit to add the KISS control byte, and do 351 * any packet forwarding in operation. 352 */ 353 void ax25_queue_xmit(struct sk_buff *skb, struct net_device *dev) 354 { 355 unsigned char *ptr; 356 357 skb->protocol = ax25_type_trans(skb, ax25_fwd_dev(dev)); 358 359 ptr = skb_push(skb, 1); 360 *ptr = 0x00; /* KISS */ 361 362 dev_queue_xmit(skb); 363 } 364 365 int ax25_check_iframes_acked(ax25_cb *ax25, unsigned short nr) 366 { 367 if (ax25->vs == nr) { 368 ax25_frames_acked(ax25, nr); 369 ax25_calculate_rtt(ax25); 370 ax25_stop_t1timer(ax25); 371 ax25_start_t3timer(ax25); 372 return 1; 373 } else { 374 if (ax25->va != nr) { 375 ax25_frames_acked(ax25, nr); 376 ax25_calculate_t1(ax25); 377 ax25_start_t1timer(ax25); 378 return 1; 379 } 380 } 381 return 0; 382 } 383 384