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 * 2000-09-04 Henner Eisen Prevent freeing a dangling skb.
18 */
19
20 #include <linux/kernel.h>
21 #include <linux/netdevice.h>
22 #include <linux/skbuff.h>
23 #include <net/sock.h>
24 #include <linux/if_arp.h>
25 #include <net/x25.h>
26
27 static int x25_receive_data(struct sk_buff *skb, struct x25_neigh *nb)
28 {
29 struct sock *sk;
30 unsigned short frametype;
31 unsigned int lci;
32
33 frametype = skb->data[2];
34 lci = ((skb->data[0] << 8) & 0xF00) + ((skb->data[1] << 0) & 0x0FF);
35
36 /*
37 * LCI of zero is always for us, and its always a link control
38 * frame.
39 */
40 if (lci == 0) {
41 x25_link_control(skb, nb, frametype);
42 return 0;
43 }
44
45 /*
46 * Find an existing socket.
47 */
48 if ((sk = x25_find_socket(lci, nb)) != NULL) {
49 int queued = 1;
50
51 skb_reset_transport_header(skb);
52 bh_lock_sock(sk);
53 if (!sock_owned_by_user(sk)) {
54 queued = x25_process_rx_frame(sk, skb);
55 } else {
56 sk_add_backlog(sk, skb);
57 }
58 bh_unlock_sock(sk);
59 sock_put(sk);
60 return queued;
61 }
62
63 /*
64 * Is is a Call Request ? if so process it.
65 */
66 if (frametype == X25_CALL_REQUEST)
67 return x25_rx_call_request(skb, nb, lci);
68
69 /*
70 * Its not a Call Request, nor is it a control frame.
71 * Can we forward it?
72 */
73
74 if (x25_forward_data(lci, nb, skb)) {
75 if (frametype == X25_CLEAR_CONFIRMATION) {
76 x25_clear_forward_by_lci(lci);
77 }
78 kfree_skb(skb);
79 return 1;
80 }
81
82 /*
83 x25_transmit_clear_request(nb, lci, 0x0D);
84 */
85
86 if (frametype != X25_CLEAR_CONFIRMATION)
87 printk(KERN_DEBUG "x25_receive_data(): unknown frame type %2x\n",frametype);
88
89 return 0;
90 }
91
92 int x25_lapb_receive_frame(struct sk_buff *skb, struct net_device *dev,
93 struct packet_type *ptype, struct net_device *orig_dev)
94 {
95 struct sk_buff *nskb;
96 struct x25_neigh *nb;
97
98 if (dev->nd_net != &init_net)
99 goto drop;
100
101 nskb = skb_copy(skb, GFP_ATOMIC);
102 if (!nskb)
103 goto drop;
104 kfree_skb(skb);
105 skb = nskb;
106
107 /*
108 * Packet received from unrecognised device, throw it away.
109 */
110 nb = x25_get_neigh(dev);
111 if (!nb) {
112 printk(KERN_DEBUG "X.25: unknown neighbour - %s\n", dev->name);
113 goto drop;
114 }
115
116 switch (skb->data[0]) {
117 case 0x00:
118 skb_pull(skb, 1);
119 if (x25_receive_data(skb, nb)) {
120 x25_neigh_put(nb);
121 goto out;
122 }
123 break;
124 case 0x01:
125 x25_link_established(nb);
126 break;
127 case 0x02:
128 x25_link_terminated(nb);
129 break;
130 }
131 x25_neigh_put(nb);
132 drop:
133 kfree_skb(skb);
134 out:
135 return 0;
136 }
137
138 void x25_establish_link(struct x25_neigh *nb)
139 {
140 struct sk_buff *skb;
141 unsigned char *ptr;
142
143 switch (nb->dev->type) {
144 case ARPHRD_X25:
145 if ((skb = alloc_skb(1, GFP_ATOMIC)) == NULL) {
146 printk(KERN_ERR "x25_dev: out of memory\n");
147 return;
148 }
149 ptr = skb_put(skb, 1);
150 *ptr = 0x01;
151 break;
152
153 #if defined(CONFIG_LLC) || defined(CONFIG_LLC_MODULE)
154 case ARPHRD_ETHER:
155 return;
156 #endif
157 default:
158 return;
159 }
160
161 skb->protocol = htons(ETH_P_X25);
162 skb->dev = nb->dev;
163
164 dev_queue_xmit(skb);
165 }
166
167 void x25_terminate_link(struct x25_neigh *nb)
168 {
169 struct sk_buff *skb;
170 unsigned char *ptr;
171
172 #if defined(CONFIG_LLC) || defined(CONFIG_LLC_MODULE)
173 if (nb->dev->type == ARPHRD_ETHER)
174 return;
175 #endif
176 if (nb->dev->type != ARPHRD_X25)
177 return;
178
179 skb = alloc_skb(1, GFP_ATOMIC);
180 if (!skb) {
181 printk(KERN_ERR "x25_dev: out of memory\n");
182 return;
183 }
184
185 ptr = skb_put(skb, 1);
186 *ptr = 0x02;
187
188 skb->protocol = htons(ETH_P_X25);
189 skb->dev = nb->dev;
190 dev_queue_xmit(skb);
191 }
192
193 void x25_send_frame(struct sk_buff *skb, struct x25_neigh *nb)
194 {
195 unsigned char *dptr;
196
197 skb_reset_network_header(skb);
198
199 switch (nb->dev->type) {
200 case ARPHRD_X25:
201 dptr = skb_push(skb, 1);
202 *dptr = 0x00;
203 break;
204
205 #if defined(CONFIG_LLC) || defined(CONFIG_LLC_MODULE)
206 case ARPHRD_ETHER:
207 kfree_skb(skb);
208 return;
209 #endif
210 default:
211 kfree_skb(skb);
212 return;
213 }
214
215 skb->protocol = htons(ETH_P_X25);
216 skb->dev = nb->dev;
217
218 dev_queue_xmit(skb);
219 }
220
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