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1da177e4 LT |
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 Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk) | |
8 | * Copyright Darryl Miles G7LED (dlm@g7led.demon.co.uk) | |
9 | */ | |
10 | #include <linux/errno.h> | |
11 | #include <linux/types.h> | |
12 | #include <linux/socket.h> | |
13 | #include <linux/in.h> | |
14 | #include <linux/kernel.h> | |
1da177e4 LT |
15 | #include <linux/timer.h> |
16 | #include <linux/string.h> | |
17 | #include <linux/sockios.h> | |
18 | #include <linux/net.h> | |
19 | #include <net/ax25.h> | |
20 | #include <linux/inet.h> | |
21 | #include <linux/netdevice.h> | |
22 | #include <linux/skbuff.h> | |
23 | #include <net/sock.h> | |
24 | #include <asm/uaccess.h> | |
25 | #include <asm/system.h> | |
26 | #include <linux/fcntl.h> | |
27 | #include <linux/mm.h> | |
28 | #include <linux/interrupt.h> | |
29 | #include <net/netrom.h> | |
30 | ||
31 | /* | |
32 | * This is where all NET/ROM frames pass, except for IP-over-NET/ROM which | |
33 | * cannot be fragmented in this manner. | |
34 | */ | |
35 | void nr_output(struct sock *sk, struct sk_buff *skb) | |
36 | { | |
37 | struct sk_buff *skbn; | |
38 | unsigned char transport[NR_TRANSPORT_LEN]; | |
39 | int err, frontlen, len; | |
40 | ||
41 | if (skb->len - NR_TRANSPORT_LEN > NR_MAX_PACKET_SIZE) { | |
42 | /* Save a copy of the Transport Header */ | |
d626f62b | 43 | skb_copy_from_linear_data(skb, transport, NR_TRANSPORT_LEN); |
1da177e4 LT |
44 | skb_pull(skb, NR_TRANSPORT_LEN); |
45 | ||
46 | frontlen = skb_headroom(skb); | |
47 | ||
48 | while (skb->len > 0) { | |
49 | if ((skbn = sock_alloc_send_skb(sk, frontlen + NR_MAX_PACKET_SIZE, 0, &err)) == NULL) | |
50 | return; | |
51 | ||
52 | skb_reserve(skbn, frontlen); | |
53 | ||
54 | len = (NR_MAX_PACKET_SIZE > skb->len) ? skb->len : NR_MAX_PACKET_SIZE; | |
55 | ||
56 | /* Copy the user data */ | |
d626f62b | 57 | skb_copy_from_linear_data(skb, skb_put(skbn, len), len); |
1da177e4 LT |
58 | skb_pull(skb, len); |
59 | ||
60 | /* Duplicate the Transport Header */ | |
61 | skb_push(skbn, NR_TRANSPORT_LEN); | |
27d7ff46 ACM |
62 | skb_copy_to_linear_data(skbn, transport, |
63 | NR_TRANSPORT_LEN); | |
1da177e4 LT |
64 | if (skb->len > 0) |
65 | skbn->data[4] |= NR_MORE_FLAG; | |
66 | ||
67 | skb_queue_tail(&sk->sk_write_queue, skbn); /* Throw it on the queue */ | |
68 | } | |
69 | ||
70 | kfree_skb(skb); | |
71 | } else { | |
72 | skb_queue_tail(&sk->sk_write_queue, skb); /* Throw it on the queue */ | |
73 | } | |
74 | ||
75 | nr_kick(sk); | |
76 | } | |
77 | ||
78 | /* | |
79 | * This procedure is passed a buffer descriptor for an iframe. It builds | |
80 | * the rest of the control part of the frame and then writes it out. | |
81 | */ | |
82 | static void nr_send_iframe(struct sock *sk, struct sk_buff *skb) | |
83 | { | |
84 | struct nr_sock *nr = nr_sk(sk); | |
85 | ||
86 | if (skb == NULL) | |
87 | return; | |
88 | ||
89 | skb->data[2] = nr->vs; | |
90 | skb->data[3] = nr->vr; | |
91 | ||
92 | if (nr->condition & NR_COND_OWN_RX_BUSY) | |
93 | skb->data[4] |= NR_CHOKE_FLAG; | |
94 | ||
95 | nr_start_idletimer(sk); | |
96 | ||
97 | nr_transmit_buffer(sk, skb); | |
98 | } | |
99 | ||
100 | void nr_send_nak_frame(struct sock *sk) | |
101 | { | |
102 | struct sk_buff *skb, *skbn; | |
103 | struct nr_sock *nr = nr_sk(sk); | |
104 | ||
105 | if ((skb = skb_peek(&nr->ack_queue)) == NULL) | |
106 | return; | |
107 | ||
108 | if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) | |
109 | return; | |
110 | ||
111 | skbn->data[2] = nr->va; | |
112 | skbn->data[3] = nr->vr; | |
113 | ||
114 | if (nr->condition & NR_COND_OWN_RX_BUSY) | |
115 | skbn->data[4] |= NR_CHOKE_FLAG; | |
116 | ||
117 | nr_transmit_buffer(sk, skbn); | |
118 | ||
119 | nr->condition &= ~NR_COND_ACK_PENDING; | |
120 | nr->vl = nr->vr; | |
121 | ||
122 | nr_stop_t1timer(sk); | |
123 | } | |
124 | ||
125 | void nr_kick(struct sock *sk) | |
126 | { | |
127 | struct nr_sock *nr = nr_sk(sk); | |
128 | struct sk_buff *skb, *skbn; | |
129 | unsigned short start, end; | |
130 | ||
131 | if (nr->state != NR_STATE_3) | |
132 | return; | |
133 | ||
134 | if (nr->condition & NR_COND_PEER_RX_BUSY) | |
135 | return; | |
136 | ||
137 | if (!skb_peek(&sk->sk_write_queue)) | |
138 | return; | |
139 | ||
140 | start = (skb_peek(&nr->ack_queue) == NULL) ? nr->va : nr->vs; | |
141 | end = (nr->va + nr->window) % NR_MODULUS; | |
142 | ||
143 | if (start == end) | |
144 | return; | |
145 | ||
146 | nr->vs = start; | |
147 | ||
148 | /* | |
149 | * Transmit data until either we're out of data to send or | |
150 | * the window is full. | |
151 | */ | |
152 | ||
153 | /* | |
154 | * Dequeue the frame and copy it. | |
155 | */ | |
156 | skb = skb_dequeue(&sk->sk_write_queue); | |
157 | ||
158 | do { | |
159 | if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) { | |
160 | skb_queue_head(&sk->sk_write_queue, skb); | |
161 | break; | |
162 | } | |
163 | ||
164 | skb_set_owner_w(skbn, sk); | |
165 | ||
166 | /* | |
167 | * Transmit the frame copy. | |
168 | */ | |
169 | nr_send_iframe(sk, skbn); | |
170 | ||
171 | nr->vs = (nr->vs + 1) % NR_MODULUS; | |
172 | ||
173 | /* | |
174 | * Requeue the original data frame. | |
175 | */ | |
176 | skb_queue_tail(&nr->ack_queue, skb); | |
177 | ||
178 | } while (nr->vs != end && | |
179 | (skb = skb_dequeue(&sk->sk_write_queue)) != NULL); | |
180 | ||
181 | nr->vl = nr->vr; | |
182 | nr->condition &= ~NR_COND_ACK_PENDING; | |
183 | ||
184 | if (!nr_t1timer_running(sk)) | |
185 | nr_start_t1timer(sk); | |
186 | } | |
187 | ||
188 | void nr_transmit_buffer(struct sock *sk, struct sk_buff *skb) | |
189 | { | |
190 | struct nr_sock *nr = nr_sk(sk); | |
191 | unsigned char *dptr; | |
192 | ||
193 | /* | |
194 | * Add the protocol byte and network header. | |
195 | */ | |
196 | dptr = skb_push(skb, NR_NETWORK_LEN); | |
197 | ||
198 | memcpy(dptr, &nr->source_addr, AX25_ADDR_LEN); | |
199 | dptr[6] &= ~AX25_CBIT; | |
200 | dptr[6] &= ~AX25_EBIT; | |
201 | dptr[6] |= AX25_SSSID_SPARE; | |
202 | dptr += AX25_ADDR_LEN; | |
203 | ||
204 | memcpy(dptr, &nr->dest_addr, AX25_ADDR_LEN); | |
205 | dptr[6] &= ~AX25_CBIT; | |
206 | dptr[6] |= AX25_EBIT; | |
207 | dptr[6] |= AX25_SSSID_SPARE; | |
208 | dptr += AX25_ADDR_LEN; | |
209 | ||
210 | *dptr++ = sysctl_netrom_network_ttl_initialiser; | |
211 | ||
212 | if (!nr_route_frame(skb, NULL)) { | |
213 | kfree_skb(skb); | |
214 | nr_disconnect(sk, ENETUNREACH); | |
215 | } | |
216 | } | |
217 | ||
218 | /* | |
219 | * The following routines are taken from page 170 of the 7th ARRL Computer | |
220 | * Networking Conference paper, as is the whole state machine. | |
221 | */ | |
222 | ||
223 | void nr_establish_data_link(struct sock *sk) | |
224 | { | |
225 | struct nr_sock *nr = nr_sk(sk); | |
226 | ||
227 | nr->condition = 0x00; | |
228 | nr->n2count = 0; | |
229 | ||
230 | nr_write_internal(sk, NR_CONNREQ); | |
231 | ||
232 | nr_stop_t2timer(sk); | |
233 | nr_stop_t4timer(sk); | |
234 | nr_stop_idletimer(sk); | |
235 | nr_start_t1timer(sk); | |
236 | } | |
237 | ||
238 | /* | |
239 | * Never send a NAK when we are CHOKEd. | |
240 | */ | |
241 | void nr_enquiry_response(struct sock *sk) | |
242 | { | |
243 | struct nr_sock *nr = nr_sk(sk); | |
244 | int frametype = NR_INFOACK; | |
245 | ||
246 | if (nr->condition & NR_COND_OWN_RX_BUSY) { | |
247 | frametype |= NR_CHOKE_FLAG; | |
248 | } else { | |
249 | if (skb_peek(&nr->reseq_queue) != NULL) | |
250 | frametype |= NR_NAK_FLAG; | |
251 | } | |
252 | ||
253 | nr_write_internal(sk, frametype); | |
254 | ||
255 | nr->vl = nr->vr; | |
256 | nr->condition &= ~NR_COND_ACK_PENDING; | |
257 | } | |
258 | ||
259 | void nr_check_iframes_acked(struct sock *sk, unsigned short nr) | |
260 | { | |
261 | struct nr_sock *nrom = nr_sk(sk); | |
262 | ||
263 | if (nrom->vs == nr) { | |
264 | nr_frames_acked(sk, nr); | |
265 | nr_stop_t1timer(sk); | |
266 | nrom->n2count = 0; | |
267 | } else { | |
268 | if (nrom->va != nr) { | |
269 | nr_frames_acked(sk, nr); | |
270 | nr_start_t1timer(sk); | |
271 | } | |
272 | } | |
273 | } |