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/*
* AX.25 release 037
*
* This code REQUIRES 2.1.15 or higher/ NET3.038
*
* This module:
* This module is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
* Most of this code is based on the SDL diagrams published in the 7th
* ARRL Computer Networking Conference papers. The diagrams have mistakes
* in them, but are mostly correct. Before you modify the code could you
* read the SDL diagrams as the code is not obvious and probably very
* easy to break;
*
* History
* AX.25 028a Jonathan(G4KLX) New state machine based on SDL diagrams.
* AX.25 028b Jonathan(G4KLX) Extracted AX25 control block from
* the sock structure.
* AX.25 029 Alan(GW4PTS) Switched to KA9Q constant names.
* Jonathan(G4KLX) Added IP mode registration.
* AX.25 030 Jonathan(G4KLX) Added AX.25 fragment reception.
* Upgraded state machine for SABME.
* Added arbitrary protocol id support.
* AX.25 031 Joerg(DL1BKE) Added DAMA support
* HaJo(DD8NE) Added Idle Disc Timer T5
* Joerg(DL1BKE) Renamed it to "IDLE" with a slightly
* different behaviour. Fixed defrag
* routine (I hope)
* AX.25 032 Darryl(G7LED) AX.25 segmentation fixed.
* AX.25 033 Jonathan(G4KLX) Remove auto-router.
* Modularisation changes.
* AX.25 035 Hans(PE1AYX) Fixed interface to IP layer.
* AX.25 036 Jonathan(G4KLX) Move DAMA code into own file.
* Joerg(DL1BKE) Fixed DAMA Slave.
* AX.25 037 Jonathan(G4KLX) New timer architecture.
* Thomas(DL9SAU) Fixed missing initialization of skb->protocol.
*/
#include <linux/config.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/socket.h>
#include <linux/in.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/timer.h>
#include <linux/string.h>
#include <linux/sockios.h>
#include <linux/net.h>
#include <net/ax25.h>
#include <linux/inet.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <linux/netfilter.h>
#include <net/sock.h>
#include <net/ip.h> /* For ip_rcv */
#include <net/arp.h> /* For arp_rcv */
#include <asm/uaccess.h>
#include <asm/system.h>
#include <linux/fcntl.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
/*
* Given a fragment, queue it on the fragment queue and if the fragment
* is complete, send it back to ax25_rx_iframe.
*/
static int ax25_rx_fragment(ax25_cb *ax25, struct sk_buff *skb)
{
struct sk_buff *skbn, *skbo;
if (ax25->fragno != 0) {
if (!(*skb->data & AX25_SEG_FIRST)) {
if ((ax25->fragno - 1) == (*skb->data & AX25_SEG_REM)) {
/* Enqueue fragment */
ax25->fragno = *skb->data & AX25_SEG_REM;
skb_pull(skb, 1); /* skip fragno */
ax25->fraglen += skb->len;
skb_queue_tail(&ax25->frag_queue, skb);
/* Last fragment received ? */
if (ax25->fragno == 0) {
skbn = alloc_skb(AX25_MAX_HEADER_LEN +
ax25->fraglen,
GFP_ATOMIC);
if (!skbn) {
skb_queue_purge(&ax25->frag_queue);
return 1;
}
skb_reserve(skbn, AX25_MAX_HEADER_LEN);
skbn->dev = ax25->ax25_dev->dev;
skbn->h.raw = skbn->data;
skbn->nh.raw = skbn->data;
/* Copy data from the fragments */
while ((skbo = skb_dequeue(&ax25->frag_queue)) != NULL) {
memcpy(skb_put(skbn, skbo->len), skbo->data, skbo->len);
kfree_skb(skbo);
}
ax25->fraglen = 0;
if (ax25_rx_iframe(ax25, skbn) == 0)
kfree_skb(skbn);
}
return 1;
}
}
} else {
/* First fragment received */
if (*skb->data & AX25_SEG_FIRST) {
skb_queue_purge(&ax25->frag_queue);
ax25->fragno = *skb->data & AX25_SEG_REM;
skb_pull(skb, 1); /* skip fragno */
ax25->fraglen = skb->len;
skb_queue_tail(&ax25->frag_queue, skb);
return 1;
}
}
return 0;
}
/*
* This is where all valid I frames are sent to, to be dispatched to
* whichever protocol requires them.
*/
int ax25_rx_iframe(ax25_cb *ax25, struct sk_buff *skb)
{
int (*func)(struct sk_buff *, ax25_cb *);
volatile int queued = 0;
unsigned char pid;
if (skb == NULL) return 0;
ax25_start_idletimer(ax25);
pid = *skb->data;
#ifdef CONFIG_INET
if (pid == AX25_P_IP) {
/* working around a TCP bug to keep additional listeners
* happy. TCP re-uses the buffer and destroys the original
* content.
*/
struct sk_buff *skbn = skb_copy(skb, GFP_ATOMIC);
if (skbn != NULL) {
kfree_skb(skb);
skb = skbn;
}
skb_pull(skb, 1); /* Remove PID */
skb->h.raw = skb->data;
skb->nh.raw = skb->data;
skb->dev = ax25->ax25_dev->dev;
skb->pkt_type = PACKET_HOST;
skb->protocol = htons(ETH_P_IP);
ip_rcv(skb, skb->dev, NULL); /* Wrong ptype */
return 1;
}
#endif
if (pid == AX25_P_SEGMENT) {
skb_pull(skb, 1); /* Remove PID */
return ax25_rx_fragment(ax25, skb);
}
if ((func = ax25_protocol_function(pid)) != NULL) {
skb_pull(skb, 1); /* Remove PID */
return (*func)(skb, ax25);
}
if (ax25->sk != NULL && ax25->ax25_dev->values[AX25_VALUES_CONMODE] == 2) {
if ((!ax25->pidincl && ax25->sk->protocol == pid) || ax25->pidincl) {
if (sock_queue_rcv_skb(ax25->sk, skb) == 0)
queued = 1;
else
ax25->condition |= AX25_COND_OWN_RX_BUSY;
}
}
return queued;
}
/*
* Higher level upcall for a LAPB frame
*/
static int ax25_process_rx_frame(ax25_cb *ax25, struct sk_buff *skb, int type, int dama)
{
int queued = 0;
if (ax25->state == AX25_STATE_0)
return 0;
switch (ax25->ax25_dev->values[AX25_VALUES_PROTOCOL]) {
case AX25_PROTO_STD_SIMPLEX:
case AX25_PROTO_STD_DUPLEX:
queued = ax25_std_frame_in(ax25, skb, type);
break;
#ifdef CONFIG_AX25_DAMA_SLAVE
case AX25_PROTO_DAMA_SLAVE:
if (dama || ax25->ax25_dev->dama.slave)
queued = ax25_ds_frame_in(ax25, skb, type);
else
queued = ax25_std_frame_in(ax25, skb, type);
break;
#endif
}
return queued;
}
static int ax25_rcv(struct sk_buff *skb, struct net_device *dev, ax25_address *dev_addr, struct packet_type *ptype)
{
struct sock *make;
struct sock *sk;
int type = 0;
ax25_digi dp, reverse_dp;
ax25_cb *ax25;
ax25_address src, dest;
ax25_address *next_digi = NULL;
ax25_dev *ax25_dev;
struct sock *raw;
int mine = 0;
int dama;
/*
* Process the AX.25/LAPB frame.
*/
skb->h.raw = skb->data;
if ((ax25_dev = ax25_dev_ax25dev(dev)) == NULL) {
kfree_skb(skb);
return 0;
}
/*
* Parse the address header.
*/
if (ax25_addr_parse(skb->data, skb->len, &src, &dest, &dp, &type, &dama) == NULL) {
kfree_skb(skb);
return 0;
}
/*
* Ours perhaps ?
*/
if (dp.lastrepeat + 1 < dp.ndigi) /* Not yet digipeated completely */
next_digi = &dp.calls[dp.lastrepeat + 1];
/*
* Pull of the AX.25 headers leaving the CTRL/PID bytes
*/
skb_pull(skb, ax25_addr_size(&dp));
/* For our port addresses ? */
if (ax25cmp(&dest, dev_addr) == 0 && dp.lastrepeat + 1 == dp.ndigi)
mine = 1;
/* Also match on any registered callsign from L3/4 */
if (!mine && ax25_listen_mine(&dest, dev) && dp.lastrepeat + 1 == dp.ndigi)
mine = 1;
/* UI frame - bypass LAPB processing */
if ((*skb->data & ~0x10) == AX25_UI && dp.lastrepeat + 1 == dp.ndigi) {
skb->h.raw = skb->data + 2; /* skip control and pid */
if ((raw = ax25_addr_match(&dest)) != NULL)
ax25_send_to_raw(raw, skb, skb->data[1]);
if (!mine && ax25cmp(&dest, (ax25_address *)dev->broadcast) != 0) {
kfree_skb(skb);
return 0;
}
/* Now we are pointing at the pid byte */
switch (skb->data[1]) {
#ifdef CONFIG_INET
case AX25_P_IP:
skb_pull(skb,2); /* drop PID/CTRL */
skb->h.raw = skb->data;
skb->nh.raw = skb->data;
skb->dev = dev;
skb->pkt_type = PACKET_HOST;
skb->protocol = htons(ETH_P_IP);
ip_rcv(skb, dev, ptype); /* Note ptype here is the wrong one, fix me later */
break;
case AX25_P_ARP:
skb_pull(skb,2);
skb->h.raw = skb->data;
skb->nh.raw = skb->data;
skb->dev = dev;
skb->pkt_type = PACKET_HOST;
skb->protocol = htons(ETH_P_ARP);
arp_rcv(skb, dev, ptype); /* Note ptype here is wrong... */
break;
#endif
case AX25_P_TEXT:
/* Now find a suitable dgram socket */
if ((sk = ax25_find_socket(&dest, &src, SOCK_DGRAM)) != NULL) {
if (atomic_read(&sk->rmem_alloc) >= sk->rcvbuf) {
kfree_skb(skb);
} else {
/*
* Remove the control and PID.
*/
skb_pull(skb, 2);
if (sock_queue_rcv_skb(sk, skb) != 0)
kfree_skb(skb);
}
} else {
kfree_skb(skb);
}
break;
default:
kfree_skb(skb); /* Will scan SOCK_AX25 RAW sockets */
break;
}
return 0;
}
/*
* Is connected mode supported on this device ?
* If not, should we DM the incoming frame (except DMs) or
* silently ignore them. For now we stay quiet.
*/
if (ax25_dev->values[AX25_VALUES_CONMODE] == 0) {
kfree_skb(skb);
return 0;
}
/* LAPB */
/* AX.25 state 1-4 */
ax25_digi_invert(&dp, &reverse_dp);
if ((ax25 = ax25_find_cb(&dest, &src, &reverse_dp, dev)) != NULL) {
/*
* Process the frame. If it is queued up internally it returns one otherwise we
* free it immediately. This routine itself wakes the user context layers so we
* do no further work
*/
if (ax25_process_rx_frame(ax25, skb, type, dama) == 0)
kfree_skb(skb);
return 0;
}
/* AX.25 state 0 (disconnected) */
/* a) received not a SABM(E) */
if ((*skb->data & ~AX25_PF) != AX25_SABM && (*skb->data & ~AX25_PF) != AX25_SABME) {
/*
* Never reply to a DM. Also ignore any connects for
* addresses that are not our interfaces and not a socket.
*/
if ((*skb->data & ~AX25_PF) != AX25_DM && mine)
ax25_return_dm(dev, &src, &dest, &dp);
kfree_skb(skb);
return 0;
}
/* b) received SABM(E) */
if (dp.lastrepeat + 1 == dp.ndigi)
sk = ax25_find_listener(&dest, 0, dev, SOCK_SEQPACKET);
else
sk = ax25_find_listener(next_digi, 1, dev, SOCK_SEQPACKET);
if (sk != NULL) {
if (sk->ack_backlog == sk->max_ack_backlog || (make = ax25_make_new(sk, ax25_dev)) == NULL) {
if (mine) ax25_return_dm(dev, &src, &dest, &dp);
kfree_skb(skb);
return 0;
}
ax25 = make->protinfo.ax25;
skb_set_owner_r(skb, make);
skb_queue_head(&sk->receive_queue, skb);
make->state = TCP_ESTABLISHED;
make->pair = sk;
sk->ack_backlog++;
} else {
if (!mine) {
kfree_skb(skb);
return 0;
}
if ((ax25 = ax25_create_cb()) == NULL) {
ax25_return_dm(dev, &src, &dest, &dp);
kfree_skb(skb);
return 0;
}
ax25_fillin_cb(ax25, ax25_dev);
}
ax25->source_addr = dest;
ax25->dest_addr = src;
/*
* Sort out any digipeated paths.
*/
if (dp.ndigi && !ax25->digipeat &&
(ax25->digipeat = kmalloc(sizeof(ax25_digi), GFP_ATOMIC)) == NULL) {
kfree_skb(skb);
ax25_destroy_socket(ax25);
return 0;
}
if (dp.ndigi == 0) {
if (ax25->digipeat != NULL) {
kfree(ax25->digipeat);
ax25->digipeat = NULL;
}
} else {
/* Reverse the source SABM's path */
memcpy(ax25->digipeat, &reverse_dp, sizeof(ax25_digi));
}
if ((*skb->data & ~AX25_PF) == AX25_SABME) {
ax25->modulus = AX25_EMODULUS;
ax25->window = ax25_dev->values[AX25_VALUES_EWINDOW];
} else {
ax25->modulus = AX25_MODULUS;
ax25->window = ax25_dev->values[AX25_VALUES_WINDOW];
}
ax25_send_control(ax25, AX25_UA, AX25_POLLON, AX25_RESPONSE);
#ifdef CONFIG_AX25_DAMA_SLAVE
if (dama && ax25->ax25_dev->values[AX25_VALUES_PROTOCOL] == AX25_PROTO_DAMA_SLAVE)
ax25_dama_on(ax25);
#endif
ax25->state = AX25_STATE_3;
ax25_insert_socket(ax25);
ax25_start_heartbeat(ax25);
ax25_start_t3timer(ax25);
ax25_start_idletimer(ax25);
if (sk != NULL) {
if (!sk->dead)
sk->data_ready(sk, skb->len);
} else {
kfree_skb(skb);
}
return 0;
}
/*
* Receive an AX.25 frame via a SLIP interface.
*/
int ax25_kiss_rcv(struct sk_buff *skb, struct net_device *dev,
struct packet_type *ptype)
{
skb->sk = NULL; /* Initially we don't know who it's for */
skb->destructor = NULL; /* Who initializes this, dammit?! */
if ((*skb->data & 0x0F) != 0) {
kfree_skb(skb); /* Not a KISS data frame */
return 0;
}
skb_pull(skb, AX25_KISS_HEADER_LEN); /* Remove the KISS byte */
return ax25_rcv(skb, dev, (ax25_address *)dev->dev_addr, ptype);
}
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