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 <linux/slab.h>
24 #include <net/sock.h>
25 #include <linux/if_arp.h>
26 #include <net/x25.h>
27 #include <net/x25device.h>
28
x25_receive_data(struct sk_buff * skb,struct x25_neigh * nb)29 static int x25_receive_data(struct sk_buff *skb, struct x25_neigh *nb)
30 {
31 struct sock *sk;
32 unsigned short frametype;
33 unsigned int lci;
34
35 frametype = skb->data[2];
36 lci = ((skb->data[0] << 8) & 0xF00) + ((skb->data[1] << 0) & 0x0FF);
37
38 /*
39 * LCI of zero is always for us, and its always a link control
40 * frame.
41 */
42 if (lci == 0) {
43 x25_link_control(skb, nb, frametype);
44 return 0;
45 }
46
47 /*
48 * Find an existing socket.
49 */
50 if ((sk = x25_find_socket(lci, nb)) != NULL) {
51 int queued = 1;
52
53 skb_reset_transport_header(skb);
54 bh_lock_sock(sk);
55 if (!sock_owned_by_user(sk)) {
56 queued = x25_process_rx_frame(sk, skb);
57 } else {
58 queued = !sk_add_backlog(sk, skb);
59 }
60 bh_unlock_sock(sk);
61 sock_put(sk);
62 return queued;
63 }
64
65 /*
66 * Is is a Call Request ? if so process it.
67 */
68 if (frametype == X25_CALL_REQUEST)
69 return x25_rx_call_request(skb, nb, lci);
70
71 /*
72 * Its not a Call Request, nor is it a control frame.
73 * Can we forward it?
74 */
75
76 if (x25_forward_data(lci, nb, skb)) {
77 if (frametype == X25_CLEAR_CONFIRMATION) {
78 x25_clear_forward_by_lci(lci);
79 }
80 kfree_skb(skb);
81 return 1;
82 }
83
84 /*
85 x25_transmit_clear_request(nb, lci, 0x0D);
86 */
87
88 if (frametype != X25_CLEAR_CONFIRMATION)
89 printk(KERN_DEBUG "x25_receive_data(): unknown frame type %2x\n",frametype);
90
91 return 0;
92 }
93
x25_lapb_receive_frame(struct sk_buff * skb,struct net_device * dev,struct packet_type * ptype,struct net_device * orig_dev)94 int x25_lapb_receive_frame(struct sk_buff *skb, struct net_device *dev,
95 struct packet_type *ptype, struct net_device *orig_dev)
96 {
97 struct sk_buff *nskb;
98 struct x25_neigh *nb;
99
100 if (!net_eq(dev_net(dev), &init_net))
101 goto drop;
102
103 nskb = skb_copy(skb, GFP_ATOMIC);
104 if (!nskb)
105 goto drop;
106 kfree_skb(skb);
107 skb = nskb;
108
109 /*
110 * Packet received from unrecognised device, throw it away.
111 */
112 nb = x25_get_neigh(dev);
113 if (!nb) {
114 printk(KERN_DEBUG "X.25: unknown neighbour - %s\n", dev->name);
115 goto drop;
116 }
117
118 switch (skb->data[0]) {
119
120 case X25_IFACE_DATA:
121 skb_pull(skb, 1);
122 if (x25_receive_data(skb, nb)) {
123 x25_neigh_put(nb);
124 goto out;
125 }
126 break;
127
128 case X25_IFACE_CONNECT:
129 x25_link_established(nb);
130 break;
131
132 case X25_IFACE_DISCONNECT:
133 x25_link_terminated(nb);
134 break;
135 }
136 x25_neigh_put(nb);
137 drop:
138 kfree_skb(skb);
139 out:
140 return 0;
141 }
142
x25_establish_link(struct x25_neigh * nb)143 void x25_establish_link(struct x25_neigh *nb)
144 {
145 struct sk_buff *skb;
146 unsigned char *ptr;
147
148 switch (nb->dev->type) {
149 case ARPHRD_X25:
150 if ((skb = alloc_skb(1, GFP_ATOMIC)) == NULL) {
151 printk(KERN_ERR "x25_dev: out of memory\n");
152 return;
153 }
154 ptr = skb_put(skb, 1);
155 *ptr = X25_IFACE_CONNECT;
156 break;
157
158 #if defined(CONFIG_LLC) || defined(CONFIG_LLC_MODULE)
159 case ARPHRD_ETHER:
160 return;
161 #endif
162 default:
163 return;
164 }
165
166 skb->protocol = htons(ETH_P_X25);
167 skb->dev = nb->dev;
168
169 dev_queue_xmit(skb);
170 }
171
x25_terminate_link(struct x25_neigh * nb)172 void x25_terminate_link(struct x25_neigh *nb)
173 {
174 struct sk_buff *skb;
175 unsigned char *ptr;
176
177 #if defined(CONFIG_LLC) || defined(CONFIG_LLC_MODULE)
178 if (nb->dev->type == ARPHRD_ETHER)
179 return;
180 #endif
181 if (nb->dev->type != ARPHRD_X25)
182 return;
183
184 skb = alloc_skb(1, GFP_ATOMIC);
185 if (!skb) {
186 printk(KERN_ERR "x25_dev: out of memory\n");
187 return;
188 }
189
190 ptr = skb_put(skb, 1);
191 *ptr = X25_IFACE_DISCONNECT;
192
193 skb->protocol = htons(ETH_P_X25);
194 skb->dev = nb->dev;
195 dev_queue_xmit(skb);
196 }
197
x25_send_frame(struct sk_buff * skb,struct x25_neigh * nb)198 void x25_send_frame(struct sk_buff *skb, struct x25_neigh *nb)
199 {
200 unsigned char *dptr;
201
202 skb_reset_network_header(skb);
203
204 switch (nb->dev->type) {
205 case ARPHRD_X25:
206 dptr = skb_push(skb, 1);
207 *dptr = X25_IFACE_DATA;
208 break;
209
210 #if defined(CONFIG_LLC) || defined(CONFIG_LLC_MODULE)
211 case ARPHRD_ETHER:
212 kfree_skb(skb);
213 return;
214 #endif
215 default:
216 kfree_skb(skb);
217 return;
218 }
219
220 skb->protocol = htons(ETH_P_X25);
221 skb->dev = nb->dev;
222
223 dev_queue_xmit(skb);
224 }
225