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/config.h> 21 #include <linux/kernel.h> 22 #include <linux/netdevice.h> 23 #include <linux/skbuff.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->h.raw = skb->data; 53 bh_lock_sock(sk); 54 if (!sock_owned_by_user(sk)) { 55 queued = x25_process_rx_frame(sk, skb); 56 } else { 57 sk_add_backlog(sk, skb); 58 } 59 bh_unlock_sock(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 * Let caller throw it away. 72 */ 73 /* 74 x25_transmit_clear_request(nb, lci, 0x0D); 75 */ 76 77 if (frametype != X25_CLEAR_CONFIRMATION) 78 printk(KERN_DEBUG "x25_receive_data(): unknown frame type %2x\n",frametype); 79 80 return 0; 81 } 82 83 int x25_lapb_receive_frame(struct sk_buff *skb, struct net_device *dev, 84 struct packet_type *ptype, struct net_device *orig_dev) 85 { 86 struct sk_buff *nskb; 87 struct x25_neigh *nb; 88 89 nskb = skb_copy(skb, GFP_ATOMIC); 90 if (!nskb) 91 goto drop; 92 kfree_skb(skb); 93 skb = nskb; 94 95 /* 96 * Packet received from unrecognised device, throw it away. 97 */ 98 nb = x25_get_neigh(dev); 99 if (!nb) { 100 printk(KERN_DEBUG "X.25: unknown neighbour - %s\n", dev->name); 101 goto drop; 102 } 103 104 switch (skb->data[0]) { 105 case 0x00: 106 skb_pull(skb, 1); 107 if (x25_receive_data(skb, nb)) { 108 x25_neigh_put(nb); 109 goto out; 110 } 111 break; 112 case 0x01: 113 x25_link_established(nb); 114 break; 115 case 0x02: 116 x25_link_terminated(nb); 117 break; 118 } 119 x25_neigh_put(nb); 120 drop: 121 kfree_skb(skb); 122 out: 123 return 0; 124 } 125 126 void x25_establish_link(struct x25_neigh *nb) 127 { 128 struct sk_buff *skb; 129 unsigned char *ptr; 130 131 switch (nb->dev->type) { 132 case ARPHRD_X25: 133 if ((skb = alloc_skb(1, GFP_ATOMIC)) == NULL) { 134 printk(KERN_ERR "x25_dev: out of memory\n"); 135 return; 136 } 137 ptr = skb_put(skb, 1); 138 *ptr = 0x01; 139 break; 140 141 #if defined(CONFIG_LLC) || defined(CONFIG_LLC_MODULE) 142 case ARPHRD_ETHER: 143 return; 144 #endif 145 default: 146 return; 147 } 148 149 skb->protocol = htons(ETH_P_X25); 150 skb->dev = nb->dev; 151 152 dev_queue_xmit(skb); 153 } 154 155 void x25_terminate_link(struct x25_neigh *nb) 156 { 157 struct sk_buff *skb; 158 unsigned char *ptr; 159 160 #if defined(CONFIG_LLC) || defined(CONFIG_LLC_MODULE) 161 if (nb->dev->type == ARPHRD_ETHER) 162 return; 163 #endif 164 if (nb->dev->type != ARPHRD_X25) 165 return; 166 167 skb = alloc_skb(1, GFP_ATOMIC); 168 if (!skb) { 169 printk(KERN_ERR "x25_dev: out of memory\n"); 170 return; 171 } 172 173 ptr = skb_put(skb, 1); 174 *ptr = 0x02; 175 176 skb->protocol = htons(ETH_P_X25); 177 skb->dev = nb->dev; 178 dev_queue_xmit(skb); 179 } 180 181 void x25_send_frame(struct sk_buff *skb, struct x25_neigh *nb) 182 { 183 unsigned char *dptr; 184 185 skb->nh.raw = skb->data; 186 187 switch (nb->dev->type) { 188 case ARPHRD_X25: 189 dptr = skb_push(skb, 1); 190 *dptr = 0x00; 191 break; 192 193 #if defined(CONFIG_LLC) || defined(CONFIG_LLC_MODULE) 194 case ARPHRD_ETHER: 195 kfree_skb(skb); 196 return; 197 #endif 198 default: 199 kfree_skb(skb); 200 return; 201 } 202 203 skb->protocol = htons(ETH_P_X25); 204 skb->dev = nb->dev; 205 206 dev_queue_xmit(skb); 207 } 208