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 28 static int x25_receive_data(struct sk_buff *skb, struct x25_neigh *nb) 29 { 30 struct sock *sk; 31 unsigned short frametype; 32 unsigned int lci; 33 34 frametype = skb->data[2]; 35 lci = ((skb->data[0] << 8) & 0xF00) + ((skb->data[1] << 0) & 0x0FF); 36 37 /* 38 * LCI of zero is always for us, and its always a link control 39 * frame. 40 */ 41 if (lci == 0) { 42 x25_link_control(skb, nb, frametype); 43 return 0; 44 } 45 46 /* 47 * Find an existing socket. 48 */ 49 if ((sk = x25_find_socket(lci, nb)) != NULL) { 50 int queued = 1; 51 52 skb_reset_transport_header(skb); 53 bh_lock_sock(sk); 54 if (!sock_owned_by_user(sk)) { 55 queued = x25_process_rx_frame(sk, skb); 56 } else { 57 queued = !sk_add_backlog(sk, skb); 58 } 59 bh_unlock_sock(sk); 60 sock_put(sk); 61 return queued; 62 } 63 64 /* 65 * Is is a Call Request ? if so process it. 66 */ 67 if (frametype == X25_CALL_REQUEST) 68 return x25_rx_call_request(skb, nb, lci); 69 70 /* 71 * Its not a Call Request, nor is it a control frame. 72 * Can we forward it? 73 */ 74 75 if (x25_forward_data(lci, nb, skb)) { 76 if (frametype == X25_CLEAR_CONFIRMATION) { 77 x25_clear_forward_by_lci(lci); 78 } 79 kfree_skb(skb); 80 return 1; 81 } 82 83 /* 84 x25_transmit_clear_request(nb, lci, 0x0D); 85 */ 86 87 if (frametype != X25_CLEAR_CONFIRMATION) 88 printk(KERN_DEBUG "x25_receive_data(): unknown frame type %2x\n",frametype); 89 90 return 0; 91 } 92 93 int x25_lapb_receive_frame(struct sk_buff *skb, struct net_device *dev, 94 struct packet_type *ptype, struct net_device *orig_dev) 95 { 96 struct sk_buff *nskb; 97 struct x25_neigh *nb; 98 99 if (!net_eq(dev_net(dev), &init_net)) 100 goto drop; 101 102 nskb = skb_copy(skb, GFP_ATOMIC); 103 if (!nskb) 104 goto drop; 105 kfree_skb(skb); 106 skb = nskb; 107 108 /* 109 * Packet received from unrecognised device, throw it away. 110 */ 111 nb = x25_get_neigh(dev); 112 if (!nb) { 113 printk(KERN_DEBUG "X.25: unknown neighbour - %s\n", dev->name); 114 goto drop; 115 } 116 117 switch (skb->data[0]) { 118 case 0x00: 119 skb_pull(skb, 1); 120 if (x25_receive_data(skb, nb)) { 121 x25_neigh_put(nb); 122 goto out; 123 } 124 break; 125 case 0x01: 126 x25_link_established(nb); 127 break; 128 case 0x02: 129 x25_link_terminated(nb); 130 break; 131 } 132 x25_neigh_put(nb); 133 drop: 134 kfree_skb(skb); 135 out: 136 return 0; 137 } 138 139 void x25_establish_link(struct x25_neigh *nb) 140 { 141 struct sk_buff *skb; 142 unsigned char *ptr; 143 144 switch (nb->dev->type) { 145 case ARPHRD_X25: 146 if ((skb = alloc_skb(1, GFP_ATOMIC)) == NULL) { 147 printk(KERN_ERR "x25_dev: out of memory\n"); 148 return; 149 } 150 ptr = skb_put(skb, 1); 151 *ptr = 0x01; 152 break; 153 154 #if defined(CONFIG_LLC) || defined(CONFIG_LLC_MODULE) 155 case ARPHRD_ETHER: 156 return; 157 #endif 158 default: 159 return; 160 } 161 162 skb->protocol = htons(ETH_P_X25); 163 skb->dev = nb->dev; 164 165 dev_queue_xmit(skb); 166 } 167 168 void x25_terminate_link(struct x25_neigh *nb) 169 { 170 struct sk_buff *skb; 171 unsigned char *ptr; 172 173 #if defined(CONFIG_LLC) || defined(CONFIG_LLC_MODULE) 174 if (nb->dev->type == ARPHRD_ETHER) 175 return; 176 #endif 177 if (nb->dev->type != ARPHRD_X25) 178 return; 179 180 skb = alloc_skb(1, GFP_ATOMIC); 181 if (!skb) { 182 printk(KERN_ERR "x25_dev: out of memory\n"); 183 return; 184 } 185 186 ptr = skb_put(skb, 1); 187 *ptr = 0x02; 188 189 skb->protocol = htons(ETH_P_X25); 190 skb->dev = nb->dev; 191 dev_queue_xmit(skb); 192 } 193 194 void x25_send_frame(struct sk_buff *skb, struct x25_neigh *nb) 195 { 196 unsigned char *dptr; 197 198 skb_reset_network_header(skb); 199 200 switch (nb->dev->type) { 201 case ARPHRD_X25: 202 dptr = skb_push(skb, 1); 203 *dptr = 0x00; 204 break; 205 206 #if defined(CONFIG_LLC) || defined(CONFIG_LLC_MODULE) 207 case ARPHRD_ETHER: 208 kfree_skb(skb); 209 return; 210 #endif 211 default: 212 kfree_skb(skb); 213 return; 214 } 215 216 skb->protocol = htons(ETH_P_X25); 217 skb->dev = nb->dev; 218 219 dev_queue_xmit(skb); 220 } 221