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