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->h.raw = skb->data; 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 return queued; 60 } 61 62 /* 63 * Is is a Call Request ? if so process it. 64 */ 65 if (frametype == X25_CALL_REQUEST) 66 return x25_rx_call_request(skb, nb, lci); 67 68 /* 69 * Its not a Call Request, nor is it a control frame. 70 * Let caller throw it away. 71 */ 72 /* 73 x25_transmit_clear_request(nb, lci, 0x0D); 74 */ 75 76 if (frametype != X25_CLEAR_CONFIRMATION) 77 printk(KERN_DEBUG "x25_receive_data(): unknown frame type %2x\n",frametype); 78 79 return 0; 80 } 81 82 int x25_lapb_receive_frame(struct sk_buff *skb, struct net_device *dev, 83 struct packet_type *ptype, struct net_device *orig_dev) 84 { 85 struct sk_buff *nskb; 86 struct x25_neigh *nb; 87 88 nskb = skb_copy(skb, GFP_ATOMIC); 89 if (!nskb) 90 goto drop; 91 kfree_skb(skb); 92 skb = nskb; 93 94 /* 95 * Packet received from unrecognised device, throw it away. 96 */ 97 nb = x25_get_neigh(dev); 98 if (!nb) { 99 printk(KERN_DEBUG "X.25: unknown neighbour - %s\n", dev->name); 100 goto drop; 101 } 102 103 switch (skb->data[0]) { 104 case 0x00: 105 skb_pull(skb, 1); 106 if (x25_receive_data(skb, nb)) { 107 x25_neigh_put(nb); 108 goto out; 109 } 110 break; 111 case 0x01: 112 x25_link_established(nb); 113 break; 114 case 0x02: 115 x25_link_terminated(nb); 116 break; 117 } 118 x25_neigh_put(nb); 119 drop: 120 kfree_skb(skb); 121 out: 122 return 0; 123 } 124 125 void x25_establish_link(struct x25_neigh *nb) 126 { 127 struct sk_buff *skb; 128 unsigned char *ptr; 129 130 switch (nb->dev->type) { 131 case ARPHRD_X25: 132 if ((skb = alloc_skb(1, GFP_ATOMIC)) == NULL) { 133 printk(KERN_ERR "x25_dev: out of memory\n"); 134 return; 135 } 136 ptr = skb_put(skb, 1); 137 *ptr = 0x01; 138 break; 139 140 #if defined(CONFIG_LLC) || defined(CONFIG_LLC_MODULE) 141 case ARPHRD_ETHER: 142 return; 143 #endif 144 default: 145 return; 146 } 147 148 skb->protocol = htons(ETH_P_X25); 149 skb->dev = nb->dev; 150 151 dev_queue_xmit(skb); 152 } 153 154 void x25_terminate_link(struct x25_neigh *nb) 155 { 156 struct sk_buff *skb; 157 unsigned char *ptr; 158 159 #if defined(CONFIG_LLC) || defined(CONFIG_LLC_MODULE) 160 if (nb->dev->type == ARPHRD_ETHER) 161 return; 162 #endif 163 if (nb->dev->type != ARPHRD_X25) 164 return; 165 166 skb = alloc_skb(1, GFP_ATOMIC); 167 if (!skb) { 168 printk(KERN_ERR "x25_dev: out of memory\n"); 169 return; 170 } 171 172 ptr = skb_put(skb, 1); 173 *ptr = 0x02; 174 175 skb->protocol = htons(ETH_P_X25); 176 skb->dev = nb->dev; 177 dev_queue_xmit(skb); 178 } 179 180 void x25_send_frame(struct sk_buff *skb, struct x25_neigh *nb) 181 { 182 unsigned char *dptr; 183 184 skb->nh.raw = skb->data; 185 186 switch (nb->dev->type) { 187 case ARPHRD_X25: 188 dptr = skb_push(skb, 1); 189 *dptr = 0x00; 190 break; 191 192 #if defined(CONFIG_LLC) || defined(CONFIG_LLC_MODULE) 193 case ARPHRD_ETHER: 194 kfree_skb(skb); 195 return; 196 #endif 197 default: 198 kfree_skb(skb); 199 return; 200 } 201 202 skb->protocol = htons(ETH_P_X25); 203 skb->dev = nb->dev; 204 205 dev_queue_xmit(skb); 206 } 207