1 | // SPDX-License-Identifier: GPL-2.0-or-later |
2 | /* |
3 | * |
4 | * Copyright (C) Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk) |
5 | * Copyright (C) Joerg Reuter DL1BKE (jreuter@yaina.de) |
6 | */ |
7 | #include <linux/errno.h> |
8 | #include <linux/types.h> |
9 | #include <linux/socket.h> |
10 | #include <linux/in.h> |
11 | #include <linux/kernel.h> |
12 | #include <linux/timer.h> |
13 | #include <linux/string.h> |
14 | #include <linux/sockios.h> |
15 | #include <linux/spinlock.h> |
16 | #include <linux/net.h> |
17 | #include <linux/gfp.h> |
18 | #include <net/ax25.h> |
19 | #include <linux/inet.h> |
20 | #include <linux/netdevice.h> |
21 | #include <linux/skbuff.h> |
22 | #include <net/sock.h> |
23 | #include <linux/uaccess.h> |
24 | #include <linux/fcntl.h> |
25 | #include <linux/mm.h> |
26 | #include <linux/interrupt.h> |
27 | |
28 | void ax25_ds_nr_error_recovery(ax25_cb *ax25) |
29 | { |
30 | ax25_ds_establish_data_link(ax25); |
31 | } |
32 | |
33 | /* |
34 | * dl1bke 960114: transmit I frames on DAMA poll |
35 | */ |
36 | void ax25_ds_enquiry_response(ax25_cb *ax25) |
37 | { |
38 | ax25_cb *ax25o; |
39 | |
40 | /* Please note that neither DK4EG's nor DG2FEF's |
41 | * DAMA spec mention the following behaviour as seen |
42 | * with TheFirmware: |
43 | * |
44 | * DB0ACH->DL1BKE <RR C P R0> [DAMA] |
45 | * DL1BKE->DB0ACH <I NR=0 NS=0> |
46 | * DL1BKE-7->DB0PRA-6 DB0ACH <I C S3 R5> |
47 | * DL1BKE->DB0ACH <RR R F R0> |
48 | * |
49 | * The Flexnet DAMA Master implementation apparently |
50 | * insists on the "proper" AX.25 behaviour: |
51 | * |
52 | * DB0ACH->DL1BKE <RR C P R0> [DAMA] |
53 | * DL1BKE->DB0ACH <RR R F R0> |
54 | * DL1BKE->DB0ACH <I NR=0 NS=0> |
55 | * DL1BKE-7->DB0PRA-6 DB0ACH <I C S3 R5> |
56 | * |
57 | * Flexnet refuses to send us *any* I frame if we send |
58 | * a REJ in case AX25_COND_REJECT is set. It is superfluous in |
59 | * this mode anyway (a RR or RNR invokes the retransmission). |
60 | * Is this a Flexnet bug? |
61 | */ |
62 | |
63 | ax25_std_enquiry_response(ax25); |
64 | |
65 | if (!(ax25->condition & AX25_COND_PEER_RX_BUSY)) { |
66 | ax25_requeue_frames(ax25); |
67 | ax25_kick(ax25); |
68 | } |
69 | |
70 | if (ax25->state == AX25_STATE_1 || ax25->state == AX25_STATE_2 || skb_peek(list_: &ax25->ack_queue) != NULL) |
71 | ax25_ds_t1_timeout(ax25); |
72 | else |
73 | ax25->n2count = 0; |
74 | |
75 | ax25_start_t3timer(ax25); |
76 | ax25_ds_set_timer(ax25->ax25_dev); |
77 | |
78 | spin_lock(lock: &ax25_list_lock); |
79 | ax25_for_each(ax25o, &ax25_list) { |
80 | if (ax25o == ax25) |
81 | continue; |
82 | |
83 | if (ax25o->ax25_dev != ax25->ax25_dev) |
84 | continue; |
85 | |
86 | if (ax25o->state == AX25_STATE_1 || ax25o->state == AX25_STATE_2) { |
87 | ax25_ds_t1_timeout(ax25o); |
88 | continue; |
89 | } |
90 | |
91 | if (!(ax25o->condition & AX25_COND_PEER_RX_BUSY) && ax25o->state == AX25_STATE_3) { |
92 | ax25_requeue_frames(ax25o); |
93 | ax25_kick(ax25o); |
94 | } |
95 | |
96 | if (ax25o->state == AX25_STATE_1 || ax25o->state == AX25_STATE_2 || skb_peek(list_: &ax25o->ack_queue) != NULL) |
97 | ax25_ds_t1_timeout(ax25o); |
98 | |
99 | /* do not start T3 for listening sockets (tnx DD8NE) */ |
100 | |
101 | if (ax25o->state != AX25_STATE_0) |
102 | ax25_start_t3timer(ax25o); |
103 | } |
104 | spin_unlock(lock: &ax25_list_lock); |
105 | } |
106 | |
107 | void ax25_ds_establish_data_link(ax25_cb *ax25) |
108 | { |
109 | ax25->condition &= AX25_COND_DAMA_MODE; |
110 | ax25->n2count = 0; |
111 | ax25_calculate_t1(ax25); |
112 | ax25_start_t1timer(ax25); |
113 | ax25_stop_t2timer(ax25); |
114 | ax25_start_t3timer(ax25); |
115 | } |
116 | |
117 | /* |
118 | * :::FIXME::: |
119 | * This is a kludge. Not all drivers recognize kiss commands. |
120 | * We need a driver level request to switch duplex mode, that does |
121 | * either SCC changing, PI config or KISS as required. Currently |
122 | * this request isn't reliable. |
123 | */ |
124 | static void ax25_kiss_cmd(ax25_dev *ax25_dev, unsigned char cmd, unsigned char param) |
125 | { |
126 | struct sk_buff *skb; |
127 | unsigned char *p; |
128 | |
129 | if (ax25_dev->dev == NULL) |
130 | return; |
131 | |
132 | if ((skb = alloc_skb(size: 2, GFP_ATOMIC)) == NULL) |
133 | return; |
134 | |
135 | skb_reset_network_header(skb); |
136 | p = skb_put(skb, len: 2); |
137 | |
138 | *p++ = cmd; |
139 | *p++ = param; |
140 | |
141 | skb->protocol = ax25_type_trans(skb, dev: ax25_dev->dev); |
142 | |
143 | dev_queue_xmit(skb); |
144 | } |
145 | |
146 | /* |
147 | * A nasty problem arises if we count the number of DAMA connections |
148 | * wrong, especially when connections on the device already existed |
149 | * and our network node (or the sysop) decides to turn on DAMA Master |
150 | * mode. We thus flag the 'real' slave connections with |
151 | * ax25->dama_slave=1 and look on every disconnect if still slave |
152 | * connections exist. |
153 | */ |
154 | static int ax25_check_dama_slave(ax25_dev *ax25_dev) |
155 | { |
156 | ax25_cb *ax25; |
157 | int res = 0; |
158 | |
159 | spin_lock(lock: &ax25_list_lock); |
160 | ax25_for_each(ax25, &ax25_list) |
161 | if (ax25->ax25_dev == ax25_dev && (ax25->condition & AX25_COND_DAMA_MODE) && ax25->state > AX25_STATE_1) { |
162 | res = 1; |
163 | break; |
164 | } |
165 | spin_unlock(lock: &ax25_list_lock); |
166 | |
167 | return res; |
168 | } |
169 | |
170 | static void ax25_dev_dama_on(ax25_dev *ax25_dev) |
171 | { |
172 | if (ax25_dev == NULL) |
173 | return; |
174 | |
175 | if (ax25_dev->dama.slave == 0) |
176 | ax25_kiss_cmd(ax25_dev, cmd: 5, param: 1); |
177 | |
178 | ax25_dev->dama.slave = 1; |
179 | ax25_ds_set_timer(ax25_dev); |
180 | } |
181 | |
182 | void ax25_dev_dama_off(ax25_dev *ax25_dev) |
183 | { |
184 | if (ax25_dev == NULL) |
185 | return; |
186 | |
187 | if (ax25_dev->dama.slave && !ax25_check_dama_slave(ax25_dev)) { |
188 | ax25_kiss_cmd(ax25_dev, cmd: 5, param: 0); |
189 | ax25_dev->dama.slave = 0; |
190 | ax25_ds_del_timer(ax25_dev); |
191 | } |
192 | } |
193 | |
194 | void ax25_dama_on(ax25_cb *ax25) |
195 | { |
196 | ax25_dev_dama_on(ax25_dev: ax25->ax25_dev); |
197 | ax25->condition |= AX25_COND_DAMA_MODE; |
198 | } |
199 | |
200 | void ax25_dama_off(ax25_cb *ax25) |
201 | { |
202 | ax25->condition &= ~AX25_COND_DAMA_MODE; |
203 | ax25_dev_dama_off(ax25_dev: ax25->ax25_dev); |
204 | } |
205 | |