1 /*
2 * X.25 Packet Layer release 002
3 *
4 * This is ALPHA test software. This code may break your machine, randomly fail to work with new
5 * releases, misbehave and/or generally screw up. It might even work.
6 *
7 * This code REQUIRES 2.1.15 or higher
8 *
9 * This module:
10 * This module is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU General Public License
12 * as published by the Free Software Foundation; either version
13 * 2 of the License, or (at your option) any later version.
14 *
15 * History
16 * X.25 001 Jonathan Naylor Started coding.
17 * X.25 002 Jonathan Naylor New timer architecture.
18 * 2000-09-04 Henner Eisen Prevented x25_output() skb leakage.
19 * 2000-10-27 Henner Eisen MSG_DONTWAIT for fragment allocation.
20 * 2000-11-10 Henner Eisen x25_send_iframe(): re-queued frames
21 * needed cleaned seq-number fields.
22 */
23
24 #include <linux/config.h>
25 #if defined(CONFIG_X25) || defined(CONFIG_X25_MODULE)
26 #include <linux/errno.h>
27 #include <linux/types.h>
28 #include <linux/socket.h>
29 #include <linux/in.h>
30 #include <linux/kernel.h>
31 #include <linux/sched.h>
32 #include <linux/timer.h>
33 #include <linux/string.h>
34 #include <linux/sockios.h>
35 #include <linux/net.h>
36 #include <linux/inet.h>
37 #include <linux/netdevice.h>
38 #include <linux/skbuff.h>
39 #include <net/sock.h>
40 #include <asm/segment.h>
41 #include <asm/system.h>
42 #include <linux/fcntl.h>
43 #include <linux/mm.h>
44 #include <linux/interrupt.h>
45 #include <net/x25.h>
46
47 static int x25_pacsize_to_bytes(unsigned int pacsize)
48 {
49 int bytes = 1;
50
51 if (pacsize == 0)
52 return 128;
53
54 while (pacsize-- > 0)
55 bytes *= 2;
56
57 return bytes;
58 }
59
60 /*
61 * This is where all X.25 information frames pass.
62 *
63 * Returns the amount of user data bytes sent on success
64 * or a negative error code on failure.
65 */
66 int x25_output(struct sock *sk, struct sk_buff *skb)
67 {
68 struct sk_buff *skbn;
69 unsigned char header[X25_EXT_MIN_LEN];
70 int err, frontlen, len, header_len, max_len;
71 int sent=0, noblock = X25_SKB_CB(skb)->flags & MSG_DONTWAIT;
72
73 header_len = (sk->protinfo.x25->neighbour->extended) ? X25_EXT_MIN_LEN : X25_STD_MIN_LEN;
74 max_len = x25_pacsize_to_bytes(sk->protinfo.x25->facilities.pacsize_out);
75
76 if (skb->len - header_len > max_len) {
77 /* Save a copy of the Header */
78 memcpy(header, skb->data, header_len);
79 skb_pull(skb, header_len);
80
81 frontlen = skb_headroom(skb);
82
83 while (skb->len > 0) {
84 if ((skbn = sock_alloc_send_skb(sk, frontlen + max_len, 0, noblock, &err)) == NULL){
85 if(err == -EWOULDBLOCK && noblock){
86 kfree_skb(skb);
87 return sent;
88 }
89 SOCK_DEBUG(sk, "x25_output: fragment allocation failed, err=%d, %d bytes sent\n", err, sent);
90 return err;
91 }
92
93 skb_reserve(skbn, frontlen);
94
95 len = (max_len > skb->len) ? skb->len : max_len;
96
97 /* Copy the user data */
98 memcpy(skb_put(skbn, len), skb->data, len);
99 skb_pull(skb, len);
100
101 /* Duplicate the Header */
102 skb_push(skbn, header_len);
103 memcpy(skbn->data, header, header_len);
104
105 if (skb->len > 0) {
106 if (sk->protinfo.x25->neighbour->extended)
107 skbn->data[3] |= X25_EXT_M_BIT;
108 else
109 skbn->data[2] |= X25_STD_M_BIT;
110 }
111
112 skb_queue_tail(&sk->write_queue, skbn);
113 sent += len;
114 }
115
116 kfree_skb(skb);
117 } else {
118 skb_queue_tail(&sk->write_queue, skb);
119 sent = skb->len - header_len;
120 }
121 return sent;
122 }
123
124 /*
125 * This procedure is passed a buffer descriptor for an iframe. It builds
126 * the rest of the control part of the frame and then writes it out.
127 */
128 static void x25_send_iframe(struct sock *sk, struct sk_buff *skb)
129 {
130 if (skb == NULL)
131 return;
132
133 if (sk->protinfo.x25->neighbour->extended) {
134 skb->data[2] = (sk->protinfo.x25->vs << 1) & 0xFE;
135 skb->data[3] &= X25_EXT_M_BIT;
136 skb->data[3] |= (sk->protinfo.x25->vr << 1) & 0xFE;
137 } else {
138 skb->data[2] &= X25_STD_M_BIT;
139 skb->data[2] |= (sk->protinfo.x25->vs << 1) & 0x0E;
140 skb->data[2] |= (sk->protinfo.x25->vr << 5) & 0xE0;
141 }
142
143 x25_transmit_link(skb, sk->protinfo.x25->neighbour);
144 }
145
146 void x25_kick(struct sock *sk)
147 {
148 struct sk_buff *skb, *skbn;
149 unsigned short start, end;
150 int modulus;
151
152 if (sk->protinfo.x25->state != X25_STATE_3)
153 return;
154
155 /*
156 * Transmit interrupt data.
157 */
158 if (!sk->protinfo.x25->intflag && skb_peek(&sk->protinfo.x25->interrupt_out_queue) != NULL) {
159 sk->protinfo.x25->intflag = 1;
160 skb = skb_dequeue(&sk->protinfo.x25->interrupt_out_queue);
161 x25_transmit_link(skb, sk->protinfo.x25->neighbour);
162 }
163
164 if (sk->protinfo.x25->condition & X25_COND_PEER_RX_BUSY)
165 return;
166
167 if (skb_peek(&sk->write_queue) == NULL)
168 return;
169
170 modulus = (sk->protinfo.x25->neighbour->extended) ? X25_EMODULUS : X25_SMODULUS;
171
172 start = (skb_peek(&sk->protinfo.x25->ack_queue) == NULL) ? sk->protinfo.x25->va : sk->protinfo.x25->vs;
173 end = (sk->protinfo.x25->va + sk->protinfo.x25->facilities.winsize_out) % modulus;
174
175 if (start == end)
176 return;
177
178 sk->protinfo.x25->vs = start;
179
180 /*
181 * Transmit data until either we're out of data to send or
182 * the window is full.
183 */
184
185 skb = skb_dequeue(&sk->write_queue);
186
187 do {
188 if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) {
189 skb_queue_head(&sk->write_queue, skb);
190 break;
191 }
192
193 skb_set_owner_w(skbn, sk);
194
195 /*
196 * Transmit the frame copy.
197 */
198 x25_send_iframe(sk, skbn);
199
200 sk->protinfo.x25->vs = (sk->protinfo.x25->vs + 1) % modulus;
201
202 /*
203 * Requeue the original data frame.
204 */
205 skb_queue_tail(&sk->protinfo.x25->ack_queue, skb);
206
207 } while (sk->protinfo.x25->vs != end && (skb = skb_dequeue(&sk->write_queue)) != NULL);
208
209 sk->protinfo.x25->vl = sk->protinfo.x25->vr;
210 sk->protinfo.x25->condition &= ~X25_COND_ACK_PENDING;
211
212 x25_stop_timer(sk);
213 }
214
215 /*
216 * The following routines are taken from page 170 of the 7th ARRL Computer
217 * Networking Conference paper, as is the whole state machine.
218 */
219
220 void x25_enquiry_response(struct sock *sk)
221 {
222 if (sk->protinfo.x25->condition & X25_COND_OWN_RX_BUSY)
223 x25_write_internal(sk, X25_RNR);
224 else
225 x25_write_internal(sk, X25_RR);
226
227 sk->protinfo.x25->vl = sk->protinfo.x25->vr;
228 sk->protinfo.x25->condition &= ~X25_COND_ACK_PENDING;
229
230 x25_stop_timer(sk);
231 }
232
233 #endif
234
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