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_net(dev) != &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