xref: /openbmc/linux/net/x25/x25_dev.c (revision e868d61272caa648214046a096e5a6bfc068dc8c)
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 	nskb = skb_copy(skb, GFP_ATOMIC);
99 	if (!nskb)
100 		goto drop;
101 	kfree_skb(skb);
102 	skb = nskb;
103 
104 	/*
105 	 * Packet received from unrecognised device, throw it away.
106 	 */
107 	nb = x25_get_neigh(dev);
108 	if (!nb) {
109 		printk(KERN_DEBUG "X.25: unknown neighbour - %s\n", dev->name);
110 		goto drop;
111 	}
112 
113 	switch (skb->data[0]) {
114 		case 0x00:
115 			skb_pull(skb, 1);
116 			if (x25_receive_data(skb, nb)) {
117 				x25_neigh_put(nb);
118 				goto out;
119 			}
120 			break;
121 		case 0x01:
122 			x25_link_established(nb);
123 			break;
124 		case 0x02:
125 			x25_link_terminated(nb);
126 			break;
127 	}
128 	x25_neigh_put(nb);
129 drop:
130 	kfree_skb(skb);
131 out:
132 	return 0;
133 }
134 
135 void x25_establish_link(struct x25_neigh *nb)
136 {
137 	struct sk_buff *skb;
138 	unsigned char *ptr;
139 
140 	switch (nb->dev->type) {
141 		case ARPHRD_X25:
142 			if ((skb = alloc_skb(1, GFP_ATOMIC)) == NULL) {
143 				printk(KERN_ERR "x25_dev: out of memory\n");
144 				return;
145 			}
146 			ptr  = skb_put(skb, 1);
147 			*ptr = 0x01;
148 			break;
149 
150 #if defined(CONFIG_LLC) || defined(CONFIG_LLC_MODULE)
151 		case ARPHRD_ETHER:
152 			return;
153 #endif
154 		default:
155 			return;
156 	}
157 
158 	skb->protocol = htons(ETH_P_X25);
159 	skb->dev      = nb->dev;
160 
161 	dev_queue_xmit(skb);
162 }
163 
164 void x25_terminate_link(struct x25_neigh *nb)
165 {
166 	struct sk_buff *skb;
167 	unsigned char *ptr;
168 
169 #if defined(CONFIG_LLC) || defined(CONFIG_LLC_MODULE)
170 	if (nb->dev->type == ARPHRD_ETHER)
171 		return;
172 #endif
173 	if (nb->dev->type != ARPHRD_X25)
174 		return;
175 
176 	skb = alloc_skb(1, GFP_ATOMIC);
177 	if (!skb) {
178 		printk(KERN_ERR "x25_dev: out of memory\n");
179 		return;
180 	}
181 
182 	ptr  = skb_put(skb, 1);
183 	*ptr = 0x02;
184 
185 	skb->protocol = htons(ETH_P_X25);
186 	skb->dev      = nb->dev;
187 	dev_queue_xmit(skb);
188 }
189 
190 void x25_send_frame(struct sk_buff *skb, struct x25_neigh *nb)
191 {
192 	unsigned char *dptr;
193 
194 	skb_reset_network_header(skb);
195 
196 	switch (nb->dev->type) {
197 		case ARPHRD_X25:
198 			dptr  = skb_push(skb, 1);
199 			*dptr = 0x00;
200 			break;
201 
202 #if defined(CONFIG_LLC) || defined(CONFIG_LLC_MODULE)
203 		case ARPHRD_ETHER:
204 			kfree_skb(skb);
205 			return;
206 #endif
207 		default:
208 			kfree_skb(skb);
209 			return;
210 	}
211 
212 	skb->protocol = htons(ETH_P_X25);
213 	skb->dev      = nb->dev;
214 
215 	dev_queue_xmit(skb);
216 }
217