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 * Copyright (C) Frederic Rible F1OAT (frible@teaser.fr) 11 */ 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/sched.h> 18 #include <linux/timer.h> 19 #include <linux/string.h> 20 #include <linux/sockios.h> 21 #include <linux/net.h> 22 #include <net/ax25.h> 23 #include <linux/inet.h> 24 #include <linux/netdevice.h> 25 #include <linux/skbuff.h> 26 #include <net/sock.h> 27 #include <net/tcp_states.h> 28 #include <asm/uaccess.h> 29 #include <asm/system.h> 30 #include <linux/fcntl.h> 31 #include <linux/mm.h> 32 #include <linux/interrupt.h> 33 34 /* 35 * This routine purges all the queues of frames. 36 */ 37 void ax25_clear_queues(ax25_cb *ax25) 38 { 39 skb_queue_purge(&ax25->write_queue); 40 skb_queue_purge(&ax25->ack_queue); 41 skb_queue_purge(&ax25->reseq_queue); 42 skb_queue_purge(&ax25->frag_queue); 43 } 44 45 /* 46 * This routine purges the input queue of those frames that have been 47 * acknowledged. This replaces the boxes labelled "V(a) <- N(r)" on the 48 * SDL diagram. 49 */ 50 void ax25_frames_acked(ax25_cb *ax25, unsigned short nr) 51 { 52 struct sk_buff *skb; 53 54 /* 55 * Remove all the ack-ed frames from the ack queue. 56 */ 57 if (ax25->va != nr) { 58 while (skb_peek(&ax25->ack_queue) != NULL && ax25->va != nr) { 59 skb = skb_dequeue(&ax25->ack_queue); 60 kfree_skb(skb); 61 ax25->va = (ax25->va + 1) % ax25->modulus; 62 } 63 } 64 } 65 66 void ax25_requeue_frames(ax25_cb *ax25) 67 { 68 struct sk_buff *skb, *skb_prev = NULL; 69 70 /* 71 * Requeue all the un-ack-ed frames on the output queue to be picked 72 * up by ax25_kick called from the timer. This arrangement handles the 73 * possibility of an empty output queue. 74 */ 75 while ((skb = skb_dequeue(&ax25->ack_queue)) != NULL) { 76 if (skb_prev == NULL) 77 skb_queue_head(&ax25->write_queue, skb); 78 else 79 skb_append(skb_prev, skb, &ax25->write_queue); 80 skb_prev = skb; 81 } 82 } 83 84 /* 85 * Validate that the value of nr is between va and vs. Return true or 86 * false for testing. 87 */ 88 int ax25_validate_nr(ax25_cb *ax25, unsigned short nr) 89 { 90 unsigned short vc = ax25->va; 91 92 while (vc != ax25->vs) { 93 if (nr == vc) return 1; 94 vc = (vc + 1) % ax25->modulus; 95 } 96 97 if (nr == ax25->vs) return 1; 98 99 return 0; 100 } 101 102 /* 103 * This routine is the centralised routine for parsing the control 104 * information for the different frame formats. 105 */ 106 int ax25_decode(ax25_cb *ax25, struct sk_buff *skb, int *ns, int *nr, int *pf) 107 { 108 unsigned char *frame; 109 int frametype = AX25_ILLEGAL; 110 111 frame = skb->data; 112 *ns = *nr = *pf = 0; 113 114 if (ax25->modulus == AX25_MODULUS) { 115 if ((frame[0] & AX25_S) == 0) { 116 frametype = AX25_I; /* I frame - carries NR/NS/PF */ 117 *ns = (frame[0] >> 1) & 0x07; 118 *nr = (frame[0] >> 5) & 0x07; 119 *pf = frame[0] & AX25_PF; 120 } else if ((frame[0] & AX25_U) == 1) { /* S frame - take out PF/NR */ 121 frametype = frame[0] & 0x0F; 122 *nr = (frame[0] >> 5) & 0x07; 123 *pf = frame[0] & AX25_PF; 124 } else if ((frame[0] & AX25_U) == 3) { /* U frame - take out PF */ 125 frametype = frame[0] & ~AX25_PF; 126 *pf = frame[0] & AX25_PF; 127 } 128 skb_pull(skb, 1); 129 } else { 130 if ((frame[0] & AX25_S) == 0) { 131 frametype = AX25_I; /* I frame - carries NR/NS/PF */ 132 *ns = (frame[0] >> 1) & 0x7F; 133 *nr = (frame[1] >> 1) & 0x7F; 134 *pf = frame[1] & AX25_EPF; 135 skb_pull(skb, 2); 136 } else if ((frame[0] & AX25_U) == 1) { /* S frame - take out PF/NR */ 137 frametype = frame[0] & 0x0F; 138 *nr = (frame[1] >> 1) & 0x7F; 139 *pf = frame[1] & AX25_EPF; 140 skb_pull(skb, 2); 141 } else if ((frame[0] & AX25_U) == 3) { /* U frame - take out PF */ 142 frametype = frame[0] & ~AX25_PF; 143 *pf = frame[0] & AX25_PF; 144 skb_pull(skb, 1); 145 } 146 } 147 148 return frametype; 149 } 150 151 /* 152 * This routine is called when the HDLC layer internally generates a 153 * command or response for the remote machine ( eg. RR, UA etc. ). 154 * Only supervisory or unnumbered frames are processed. 155 */ 156 void ax25_send_control(ax25_cb *ax25, int frametype, int poll_bit, int type) 157 { 158 struct sk_buff *skb; 159 unsigned char *dptr; 160 161 if ((skb = alloc_skb(ax25->ax25_dev->dev->hard_header_len + 2, GFP_ATOMIC)) == NULL) 162 return; 163 164 skb_reserve(skb, ax25->ax25_dev->dev->hard_header_len); 165 166 skb->nh.raw = skb->data; 167 168 /* Assume a response - address structure for DTE */ 169 if (ax25->modulus == AX25_MODULUS) { 170 dptr = skb_put(skb, 1); 171 *dptr = frametype; 172 *dptr |= (poll_bit) ? AX25_PF : 0; 173 if ((frametype & AX25_U) == AX25_S) /* S frames carry NR */ 174 *dptr |= (ax25->vr << 5); 175 } else { 176 if ((frametype & AX25_U) == AX25_U) { 177 dptr = skb_put(skb, 1); 178 *dptr = frametype; 179 *dptr |= (poll_bit) ? AX25_PF : 0; 180 } else { 181 dptr = skb_put(skb, 2); 182 dptr[0] = frametype; 183 dptr[1] = (ax25->vr << 1); 184 dptr[1] |= (poll_bit) ? AX25_EPF : 0; 185 } 186 } 187 188 ax25_transmit_buffer(ax25, skb, type); 189 } 190 191 /* 192 * Send a 'DM' to an unknown connection attempt, or an invalid caller. 193 * 194 * Note: src here is the sender, thus it's the target of the DM 195 */ 196 void ax25_return_dm(struct net_device *dev, ax25_address *src, ax25_address *dest, ax25_digi *digi) 197 { 198 struct sk_buff *skb; 199 char *dptr; 200 ax25_digi retdigi; 201 202 if (dev == NULL) 203 return; 204 205 if ((skb = alloc_skb(dev->hard_header_len + 1, GFP_ATOMIC)) == NULL) 206 return; /* Next SABM will get DM'd */ 207 208 skb_reserve(skb, dev->hard_header_len); 209 skb->nh.raw = skb->data; 210 211 ax25_digi_invert(digi, &retdigi); 212 213 dptr = skb_put(skb, 1); 214 215 *dptr = AX25_DM | AX25_PF; 216 217 /* 218 * Do the address ourselves 219 */ 220 dptr = skb_push(skb, ax25_addr_size(digi)); 221 dptr += ax25_addr_build(dptr, dest, src, &retdigi, AX25_RESPONSE, AX25_MODULUS); 222 223 ax25_queue_xmit(skb, dev); 224 } 225 226 /* 227 * Exponential backoff for AX.25 228 */ 229 void ax25_calculate_t1(ax25_cb *ax25) 230 { 231 int n, t = 2; 232 233 switch (ax25->backoff) { 234 case 0: 235 break; 236 237 case 1: 238 t += 2 * ax25->n2count; 239 break; 240 241 case 2: 242 for (n = 0; n < ax25->n2count; n++) 243 t *= 2; 244 if (t > 8) t = 8; 245 break; 246 } 247 248 ax25->t1 = t * ax25->rtt; 249 } 250 251 /* 252 * Calculate the Round Trip Time 253 */ 254 void ax25_calculate_rtt(ax25_cb *ax25) 255 { 256 if (ax25->backoff == 0) 257 return; 258 259 if (ax25_t1timer_running(ax25) && ax25->n2count == 0) 260 ax25->rtt = (9 * ax25->rtt + ax25->t1 - ax25_display_timer(&ax25->t1timer)) / 10; 261 262 if (ax25->rtt < AX25_T1CLAMPLO) 263 ax25->rtt = AX25_T1CLAMPLO; 264 265 if (ax25->rtt > AX25_T1CLAMPHI) 266 ax25->rtt = AX25_T1CLAMPHI; 267 } 268 269 void ax25_disconnect(ax25_cb *ax25, int reason) 270 { 271 ax25_clear_queues(ax25); 272 273 ax25_stop_t1timer(ax25); 274 ax25_stop_t2timer(ax25); 275 ax25_stop_t3timer(ax25); 276 ax25_stop_idletimer(ax25); 277 278 ax25->state = AX25_STATE_0; 279 280 ax25_link_failed(ax25, reason); 281 282 if (ax25->sk != NULL) { 283 bh_lock_sock(ax25->sk); 284 ax25->sk->sk_state = TCP_CLOSE; 285 ax25->sk->sk_err = reason; 286 ax25->sk->sk_shutdown |= SEND_SHUTDOWN; 287 if (!sock_flag(ax25->sk, SOCK_DEAD)) { 288 ax25->sk->sk_state_change(ax25->sk); 289 sock_set_flag(ax25->sk, SOCK_DEAD); 290 } 291 bh_unlock_sock(ax25->sk); 292 } 293 } 294