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.
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)
12 #include <linux/errno.h>
13 #include <linux/types.h>
14 #include <linux/socket.h>
16 #include <linux/kernel.h>
17 #include <linux/timer.h>
18 #include <linux/string.h>
19 #include <linux/sockios.h>
20 #include <linux/net.h>
22 #include <linux/inet.h>
23 #include <linux/netdevice.h>
24 #include <linux/skbuff.h>
26 #include <net/tcp_states.h>
27 #include <asm/uaccess.h>
28 #include <asm/system.h>
29 #include <linux/fcntl.h>
31 #include <linux/interrupt.h>
34 * This routine purges all the queues of frames.
36 void ax25_clear_queues(ax25_cb
*ax25
)
38 skb_queue_purge(&ax25
->write_queue
);
39 skb_queue_purge(&ax25
->ack_queue
);
40 skb_queue_purge(&ax25
->reseq_queue
);
41 skb_queue_purge(&ax25
->frag_queue
);
45 * This routine purges the input queue of those frames that have been
46 * acknowledged. This replaces the boxes labelled "V(a) <- N(r)" on the
49 void ax25_frames_acked(ax25_cb
*ax25
, unsigned short nr
)
54 * Remove all the ack-ed frames from the ack queue.
57 while (skb_peek(&ax25
->ack_queue
) != NULL
&& ax25
->va
!= nr
) {
58 skb
= skb_dequeue(&ax25
->ack_queue
);
60 ax25
->va
= (ax25
->va
+ 1) % ax25
->modulus
;
65 void ax25_requeue_frames(ax25_cb
*ax25
)
70 * Requeue all the un-ack-ed frames on the output queue to be picked
71 * up by ax25_kick called from the timer. This arrangement handles the
72 * possibility of an empty output queue.
74 while ((skb
= skb_dequeue_tail(&ax25
->ack_queue
)) != NULL
)
75 skb_queue_head(&ax25
->write_queue
, skb
);
79 * Validate that the value of nr is between va and vs. Return true or
82 int ax25_validate_nr(ax25_cb
*ax25
, unsigned short nr
)
84 unsigned short vc
= ax25
->va
;
86 while (vc
!= ax25
->vs
) {
87 if (nr
== vc
) return 1;
88 vc
= (vc
+ 1) % ax25
->modulus
;
91 if (nr
== ax25
->vs
) return 1;
97 * This routine is the centralised routine for parsing the control
98 * information for the different frame formats.
100 int ax25_decode(ax25_cb
*ax25
, struct sk_buff
*skb
, int *ns
, int *nr
, int *pf
)
102 unsigned char *frame
;
103 int frametype
= AX25_ILLEGAL
;
108 if (ax25
->modulus
== AX25_MODULUS
) {
109 if ((frame
[0] & AX25_S
) == 0) {
110 frametype
= AX25_I
; /* I frame - carries NR/NS/PF */
111 *ns
= (frame
[0] >> 1) & 0x07;
112 *nr
= (frame
[0] >> 5) & 0x07;
113 *pf
= frame
[0] & AX25_PF
;
114 } else if ((frame
[0] & AX25_U
) == 1) { /* S frame - take out PF/NR */
115 frametype
= frame
[0] & 0x0F;
116 *nr
= (frame
[0] >> 5) & 0x07;
117 *pf
= frame
[0] & AX25_PF
;
118 } else if ((frame
[0] & AX25_U
) == 3) { /* U frame - take out PF */
119 frametype
= frame
[0] & ~AX25_PF
;
120 *pf
= frame
[0] & AX25_PF
;
124 if ((frame
[0] & AX25_S
) == 0) {
125 frametype
= AX25_I
; /* I frame - carries NR/NS/PF */
126 *ns
= (frame
[0] >> 1) & 0x7F;
127 *nr
= (frame
[1] >> 1) & 0x7F;
128 *pf
= frame
[1] & AX25_EPF
;
130 } else if ((frame
[0] & AX25_U
) == 1) { /* S frame - take out PF/NR */
131 frametype
= frame
[0] & 0x0F;
132 *nr
= (frame
[1] >> 1) & 0x7F;
133 *pf
= frame
[1] & AX25_EPF
;
135 } else if ((frame
[0] & AX25_U
) == 3) { /* U frame - take out PF */
136 frametype
= frame
[0] & ~AX25_PF
;
137 *pf
= frame
[0] & AX25_PF
;
146 * This routine is called when the HDLC layer internally generates a
147 * command or response for the remote machine ( eg. RR, UA etc. ).
148 * Only supervisory or unnumbered frames are processed.
150 void ax25_send_control(ax25_cb
*ax25
, int frametype
, int poll_bit
, int type
)
155 if ((skb
= alloc_skb(ax25
->ax25_dev
->dev
->hard_header_len
+ 2, GFP_ATOMIC
)) == NULL
)
158 skb_reserve(skb
, ax25
->ax25_dev
->dev
->hard_header_len
);
160 skb_reset_network_header(skb
);
162 /* Assume a response - address structure for DTE */
163 if (ax25
->modulus
== AX25_MODULUS
) {
164 dptr
= skb_put(skb
, 1);
166 *dptr
|= (poll_bit
) ? AX25_PF
: 0;
167 if ((frametype
& AX25_U
) == AX25_S
) /* S frames carry NR */
168 *dptr
|= (ax25
->vr
<< 5);
170 if ((frametype
& AX25_U
) == AX25_U
) {
171 dptr
= skb_put(skb
, 1);
173 *dptr
|= (poll_bit
) ? AX25_PF
: 0;
175 dptr
= skb_put(skb
, 2);
177 dptr
[1] = (ax25
->vr
<< 1);
178 dptr
[1] |= (poll_bit
) ? AX25_EPF
: 0;
182 ax25_transmit_buffer(ax25
, skb
, type
);
186 * Send a 'DM' to an unknown connection attempt, or an invalid caller.
188 * Note: src here is the sender, thus it's the target of the DM
190 void ax25_return_dm(struct net_device
*dev
, ax25_address
*src
, ax25_address
*dest
, ax25_digi
*digi
)
199 if ((skb
= alloc_skb(dev
->hard_header_len
+ 1, GFP_ATOMIC
)) == NULL
)
200 return; /* Next SABM will get DM'd */
202 skb_reserve(skb
, dev
->hard_header_len
);
203 skb_reset_network_header(skb
);
205 ax25_digi_invert(digi
, &retdigi
);
207 dptr
= skb_put(skb
, 1);
209 *dptr
= AX25_DM
| AX25_PF
;
212 * Do the address ourselves
214 dptr
= skb_push(skb
, ax25_addr_size(digi
));
215 dptr
+= ax25_addr_build(dptr
, dest
, src
, &retdigi
, AX25_RESPONSE
, AX25_MODULUS
);
217 ax25_queue_xmit(skb
, dev
);
221 * Exponential backoff for AX.25
223 void ax25_calculate_t1(ax25_cb
*ax25
)
227 switch (ax25
->backoff
) {
232 t
+= 2 * ax25
->n2count
;
236 for (n
= 0; n
< ax25
->n2count
; n
++)
242 ax25
->t1
= t
* ax25
->rtt
;
246 * Calculate the Round Trip Time
248 void ax25_calculate_rtt(ax25_cb
*ax25
)
250 if (ax25
->backoff
== 0)
253 if (ax25_t1timer_running(ax25
) && ax25
->n2count
== 0)
254 ax25
->rtt
= (9 * ax25
->rtt
+ ax25
->t1
- ax25_display_timer(&ax25
->t1timer
)) / 10;
256 if (ax25
->rtt
< AX25_T1CLAMPLO
)
257 ax25
->rtt
= AX25_T1CLAMPLO
;
259 if (ax25
->rtt
> AX25_T1CLAMPHI
)
260 ax25
->rtt
= AX25_T1CLAMPHI
;
263 void ax25_disconnect(ax25_cb
*ax25
, int reason
)
265 ax25_clear_queues(ax25
);
267 ax25_stop_t1timer(ax25
);
268 ax25_stop_t2timer(ax25
);
269 ax25_stop_t3timer(ax25
);
270 ax25_stop_idletimer(ax25
);
272 ax25
->state
= AX25_STATE_0
;
274 ax25_link_failed(ax25
, reason
);
276 if (ax25
->sk
!= NULL
) {
278 bh_lock_sock(ax25
->sk
);
279 ax25
->sk
->sk_state
= TCP_CLOSE
;
280 ax25
->sk
->sk_err
= reason
;
281 ax25
->sk
->sk_shutdown
|= SEND_SHUTDOWN
;
282 if (!sock_flag(ax25
->sk
, SOCK_DEAD
)) {
283 ax25
->sk
->sk_state_change(ax25
->sk
);
284 sock_set_flag(ax25
->sk
, SOCK_DEAD
);
286 bh_unlock_sock(ax25
->sk
);
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