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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> | |
15 | #include <linux/sched.h> | |
16 | #include <linux/timer.h> | |
17 | #include <linux/string.h> | |
18 | #include <linux/sockios.h> | |
19 | #include <linux/net.h> | |
20 | #include <net/ax25.h> | |
21 | #include <linux/inet.h> | |
22 | #include <linux/netdevice.h> | |
23 | #include <linux/skbuff.h> | |
24 | #include <net/sock.h> | |
25 | #include <asm/uaccess.h> | |
26 | #include <asm/system.h> | |
27 | #include <linux/fcntl.h> | |
28 | #include <linux/mm.h> | |
29 | #include <linux/interrupt.h> | |
30 | #include <net/netrom.h> | |
31 | ||
32 | /* | |
33 | * This is where all NET/ROM frames pass, except for IP-over-NET/ROM which | |
34 | * cannot be fragmented in this manner. | |
35 | */ | |
36 | void nr_output(struct sock *sk, struct sk_buff *skb) | |
37 | { | |
38 | struct sk_buff *skbn; | |
39 | unsigned char transport[NR_TRANSPORT_LEN]; | |
40 | int err, frontlen, len; | |
41 | ||
42 | if (skb->len - NR_TRANSPORT_LEN > NR_MAX_PACKET_SIZE) { | |
43 | /* Save a copy of the Transport Header */ | |
44 | memcpy(transport, skb->data, NR_TRANSPORT_LEN); | |
45 | skb_pull(skb, NR_TRANSPORT_LEN); | |
46 | ||
47 | frontlen = skb_headroom(skb); | |
48 | ||
49 | while (skb->len > 0) { | |
50 | if ((skbn = sock_alloc_send_skb(sk, frontlen + NR_MAX_PACKET_SIZE, 0, &err)) == NULL) | |
51 | return; | |
52 | ||
53 | skb_reserve(skbn, frontlen); | |
54 | ||
55 | len = (NR_MAX_PACKET_SIZE > skb->len) ? skb->len : NR_MAX_PACKET_SIZE; | |
56 | ||
57 | /* Copy the user data */ | |
58 | memcpy(skb_put(skbn, len), skb->data, len); | |
59 | skb_pull(skb, len); | |
60 | ||
61 | /* Duplicate the Transport Header */ | |
62 | skb_push(skbn, NR_TRANSPORT_LEN); | |
63 | memcpy(skbn->data, transport, NR_TRANSPORT_LEN); | |
64 | ||
65 | if (skb->len > 0) | |
66 | skbn->data[4] |= NR_MORE_FLAG; | |
67 | ||
68 | skb_queue_tail(&sk->sk_write_queue, skbn); /* Throw it on the queue */ | |
69 | } | |
70 | ||
71 | kfree_skb(skb); | |
72 | } else { | |
73 | skb_queue_tail(&sk->sk_write_queue, skb); /* Throw it on the queue */ | |
74 | } | |
75 | ||
76 | nr_kick(sk); | |
77 | } | |
78 | ||
79 | /* | |
80 | * This procedure is passed a buffer descriptor for an iframe. It builds | |
81 | * the rest of the control part of the frame and then writes it out. | |
82 | */ | |
83 | static void nr_send_iframe(struct sock *sk, struct sk_buff *skb) | |
84 | { | |
85 | struct nr_sock *nr = nr_sk(sk); | |
86 | ||
87 | if (skb == NULL) | |
88 | return; | |
89 | ||
90 | skb->data[2] = nr->vs; | |
91 | skb->data[3] = nr->vr; | |
92 | ||
93 | if (nr->condition & NR_COND_OWN_RX_BUSY) | |
94 | skb->data[4] |= NR_CHOKE_FLAG; | |
95 | ||
96 | nr_start_idletimer(sk); | |
97 | ||
98 | nr_transmit_buffer(sk, skb); | |
99 | } | |
100 | ||
101 | void nr_send_nak_frame(struct sock *sk) | |
102 | { | |
103 | struct sk_buff *skb, *skbn; | |
104 | struct nr_sock *nr = nr_sk(sk); | |
105 | ||
106 | if ((skb = skb_peek(&nr->ack_queue)) == NULL) | |
107 | return; | |
108 | ||
109 | if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) | |
110 | return; | |
111 | ||
112 | skbn->data[2] = nr->va; | |
113 | skbn->data[3] = nr->vr; | |
114 | ||
115 | if (nr->condition & NR_COND_OWN_RX_BUSY) | |
116 | skbn->data[4] |= NR_CHOKE_FLAG; | |
117 | ||
118 | nr_transmit_buffer(sk, skbn); | |
119 | ||
120 | nr->condition &= ~NR_COND_ACK_PENDING; | |
121 | nr->vl = nr->vr; | |
122 | ||
123 | nr_stop_t1timer(sk); | |
124 | } | |
125 | ||
126 | void nr_kick(struct sock *sk) | |
127 | { | |
128 | struct nr_sock *nr = nr_sk(sk); | |
129 | struct sk_buff *skb, *skbn; | |
130 | unsigned short start, end; | |
131 | ||
132 | if (nr->state != NR_STATE_3) | |
133 | return; | |
134 | ||
135 | if (nr->condition & NR_COND_PEER_RX_BUSY) | |
136 | return; | |
137 | ||
138 | if (!skb_peek(&sk->sk_write_queue)) | |
139 | return; | |
140 | ||
141 | start = (skb_peek(&nr->ack_queue) == NULL) ? nr->va : nr->vs; | |
142 | end = (nr->va + nr->window) % NR_MODULUS; | |
143 | ||
144 | if (start == end) | |
145 | return; | |
146 | ||
147 | nr->vs = start; | |
148 | ||
149 | /* | |
150 | * Transmit data until either we're out of data to send or | |
151 | * the window is full. | |
152 | */ | |
153 | ||
154 | /* | |
155 | * Dequeue the frame and copy it. | |
156 | */ | |
157 | skb = skb_dequeue(&sk->sk_write_queue); | |
158 | ||
159 | do { | |
160 | if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) { | |
161 | skb_queue_head(&sk->sk_write_queue, skb); | |
162 | break; | |
163 | } | |
164 | ||
165 | skb_set_owner_w(skbn, sk); | |
166 | ||
167 | /* | |
168 | * Transmit the frame copy. | |
169 | */ | |
170 | nr_send_iframe(sk, skbn); | |
171 | ||
172 | nr->vs = (nr->vs + 1) % NR_MODULUS; | |
173 | ||
174 | /* | |
175 | * Requeue the original data frame. | |
176 | */ | |
177 | skb_queue_tail(&nr->ack_queue, skb); | |
178 | ||
179 | } while (nr->vs != end && | |
180 | (skb = skb_dequeue(&sk->sk_write_queue)) != NULL); | |
181 | ||
182 | nr->vl = nr->vr; | |
183 | nr->condition &= ~NR_COND_ACK_PENDING; | |
184 | ||
185 | if (!nr_t1timer_running(sk)) | |
186 | nr_start_t1timer(sk); | |
187 | } | |
188 | ||
189 | void nr_transmit_buffer(struct sock *sk, struct sk_buff *skb) | |
190 | { | |
191 | struct nr_sock *nr = nr_sk(sk); | |
192 | unsigned char *dptr; | |
193 | ||
194 | /* | |
195 | * Add the protocol byte and network header. | |
196 | */ | |
197 | dptr = skb_push(skb, NR_NETWORK_LEN); | |
198 | ||
199 | memcpy(dptr, &nr->source_addr, AX25_ADDR_LEN); | |
200 | dptr[6] &= ~AX25_CBIT; | |
201 | dptr[6] &= ~AX25_EBIT; | |
202 | dptr[6] |= AX25_SSSID_SPARE; | |
203 | dptr += AX25_ADDR_LEN; | |
204 | ||
205 | memcpy(dptr, &nr->dest_addr, AX25_ADDR_LEN); | |
206 | dptr[6] &= ~AX25_CBIT; | |
207 | dptr[6] |= AX25_EBIT; | |
208 | dptr[6] |= AX25_SSSID_SPARE; | |
209 | dptr += AX25_ADDR_LEN; | |
210 | ||
211 | *dptr++ = sysctl_netrom_network_ttl_initialiser; | |
212 | ||
213 | if (!nr_route_frame(skb, NULL)) { | |
214 | kfree_skb(skb); | |
215 | nr_disconnect(sk, ENETUNREACH); | |
216 | } | |
217 | } | |
218 | ||
219 | /* | |
220 | * The following routines are taken from page 170 of the 7th ARRL Computer | |
221 | * Networking Conference paper, as is the whole state machine. | |
222 | */ | |
223 | ||
224 | void nr_establish_data_link(struct sock *sk) | |
225 | { | |
226 | struct nr_sock *nr = nr_sk(sk); | |
227 | ||
228 | nr->condition = 0x00; | |
229 | nr->n2count = 0; | |
230 | ||
231 | nr_write_internal(sk, NR_CONNREQ); | |
232 | ||
233 | nr_stop_t2timer(sk); | |
234 | nr_stop_t4timer(sk); | |
235 | nr_stop_idletimer(sk); | |
236 | nr_start_t1timer(sk); | |
237 | } | |
238 | ||
239 | /* | |
240 | * Never send a NAK when we are CHOKEd. | |
241 | */ | |
242 | void nr_enquiry_response(struct sock *sk) | |
243 | { | |
244 | struct nr_sock *nr = nr_sk(sk); | |
245 | int frametype = NR_INFOACK; | |
246 | ||
247 | if (nr->condition & NR_COND_OWN_RX_BUSY) { | |
248 | frametype |= NR_CHOKE_FLAG; | |
249 | } else { | |
250 | if (skb_peek(&nr->reseq_queue) != NULL) | |
251 | frametype |= NR_NAK_FLAG; | |
252 | } | |
253 | ||
254 | nr_write_internal(sk, frametype); | |
255 | ||
256 | nr->vl = nr->vr; | |
257 | nr->condition &= ~NR_COND_ACK_PENDING; | |
258 | } | |
259 | ||
260 | void nr_check_iframes_acked(struct sock *sk, unsigned short nr) | |
261 | { | |
262 | struct nr_sock *nrom = nr_sk(sk); | |
263 | ||
264 | if (nrom->vs == nr) { | |
265 | nr_frames_acked(sk, nr); | |
266 | nr_stop_t1timer(sk); | |
267 | nrom->n2count = 0; | |
268 | } else { | |
269 | if (nrom->va != nr) { | |
270 | nr_frames_acked(sk, nr); | |
271 | nr_start_t1timer(sk); | |
272 | } | |
273 | } | |
274 | } |