strip.c

linux-2.6.15.6

/*
 * Copyright 1996 The Board of Trustees of The Leland Stanford
 * Junior University. All Rights Reserved.
 *
 * Permission to use, copy, modify, and distribute this
 * software and its documentation for any purpose and without
 * fee is hereby granted, provided that the above copyright
 * notice appear in all copies.  Stanford University
 * makes no representations about the suitability of this
 * software for any purpose.  It is provided "as is" without
 * express or implied warranty.
 *
 * strip.c	This module implements Starmode Radio IP (STRIP)
 *		for kernel-based devices like TTY.  It interfaces between a
 *		raw TTY, and the kernel's INET protocol layers (via DDI).
 *
 * Version:	@(#)strip.c	1.3	July 1997
 *
 * Author:	Stuart Cheshire <[e-mail]>
 *
 * Fixes:	v0.9 12th Feb 1996 (SC)
 *		New byte stuffing (2+6 run-length encoding)
 *		New watchdog timer task
 *		New Protocol key (SIP0)
 *		
 *		v0.9.1 3rd March 1996 (SC)
 *		Changed to dynamic device allocation -- no more compile
 *		time (or boot time) limit on the number of STRIP devices.
 *		
 *		v0.9.2 13th March 1996 (SC)
 *		Uses arp cache lookups (but doesn't send arp packets yet)
 *		
 *		v0.9.3 17th April 1996 (SC)
 *		Fixed bug where STR_ERROR flag was getting set unneccessarily
 *		(causing otherwise good packets to be unneccessarily dropped)
 *		
 *		v0.9.4 27th April 1996 (SC)
 *		First attempt at using "&COMMAND" Starmode AT commands
 *		
 *		v0.9.5 29th May 1996 (SC)
 *		First attempt at sending (unicast) ARP packets
 *		
 *		v0.9.6 5th June 1996 (Elliot)
 *		Put "message level" tags in every "printk" statement
 *		
 *		v0.9.7 13th June 1996 (laik)
 *		Added support for the /proc fs
 *
 *              v0.9.8 July 1996 (Mema)
 *              Added packet logging
 *
 *              v1.0 November 1996 (SC)
 *              Fixed (severe) memory leaks in the /proc fs code
 *              Fixed race conditions in the logging code
 *
 *              v1.1 January 1997 (SC)
 *              Deleted packet logging (use tcpdump instead)
 *              Added support for Metricom Firmware v204 features
 *              (like message checksums)
 *
 *              v1.2 January 1997 (SC)
 *              Put portables list back in
 *
 *              v1.3 July 1997 (SC)
 *              Made STRIP driver set the radio's baud rate automatically.
 *              It is no longer necessarily to manually set the radio's
 *              rate permanently to 115200 -- the driver handles setting
 *              the rate automatically.
 */

#ifdef MODULE
static const char StripVersion[] = "1.3A-STUART.CHESHIRE-MODULAR";
#else
static const char StripVersion[] = "1.3A-STUART.CHESHIRE";
#endif

#define TICKLE_TIMERS 0
#define EXT_COUNTERS 1


/************************************************************************/
/* Header files								*/

#include <linux/config.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/bitops.h>
#include <asm/system.h>
#include <asm/uaccess.h>

# include <linux/ctype.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/in.h>
#include <linux/tty.h>
#include <linux/errno.h>
#include <linux/netdevice.h>
#include <linux/inetdevice.h>
#include <linux/etherdevice.h>
#include <linux/skbuff.h>
#include <linux/if_arp.h>
#include <linux/if_strip.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/serial.h>
#include <linux/serialP.h>
#include <linux/rcupdate.h>
#include <net/arp.h>

#include <linux/ip.h>
#include <linux/tcp.h>
#include <linux/time.h>


/************************************************************************/
/* Useful structures and definitions					*/

/*
 * A MetricomKey identifies the protocol being carried inside a Metricom
 * Starmode packet.
 */

typedef union {
	__u8 c[4];
	__u32 l;
} MetricomKey;

/*
 * An IP address can be viewed as four bytes in memory (which is what it is) or as
 * a single 32-bit long (which is convenient for assignment, equality testing etc.)
 */

typedef union {
	__u8 b[4];
	__u32 l;
} IPaddr;

/*
 * A MetricomAddressString is used to hold a printable representation of
 * a Metricom address.
 */

typedef struct {
	__u8 c[24];
} MetricomAddressString;

/* Encapsulation can expand packet of size x to 65/64x + 1
 * Sent packet looks like "<CR>*<address>*<key><encaps payload><CR>"
 *                           1 1   1-18  1  4         ?         1
 * eg.                     <CR>*0000-1234*SIP0<encaps payload><CR>
 * We allow 31 bytes for the stars, the key, the address and the <CR>s
 */
#define STRIP_ENCAP_SIZE(X) (32 + (X)*65L/64L)

/*
 * A STRIP_Header is never really sent over the radio, but making a dummy
 * header for internal use within the kernel that looks like an Ethernet
 * header makes certain other software happier. For example, tcpdump
 * already understands Ethernet headers.
 */

typedef struct {
	MetricomAddress dst_addr;	/* Destination address, e.g. "0000-1234"   */
	MetricomAddress src_addr;	/* Source address, e.g. "0000-5678"        */
	unsigned short protocol;	/* The protocol type, using Ethernet codes */
} STRIP_Header;

typedef struct {
	char c[60];
} MetricomNode;

#define NODE_TABLE_SIZE 32
typedef struct {
	struct timeval timestamp;
	int num_nodes;
	MetricomNode node[NODE_TABLE_SIZE];
} MetricomNodeTable;

enum { FALSE = 0, TRUE = 1 };

/*
 * Holds the radio's firmware version.
 */
typedef struct {
	char c[50];
} FirmwareVersion;

/*
 * Holds the radio's serial number.
 */
typedef struct {
	char c[18];
} SerialNumber;

/*
 * Holds the radio's battery voltage.
 */
typedef struct {
	char c[11];
} BatteryVoltage;

typedef struct {
	char c[8];
} char8;

enum {
	NoStructure = 0,	/* Really old firmware */
	StructuredMessages = 1,	/* Parsable AT response msgs */
	ChecksummedMessages = 2	/* Parsable AT response msgs with checksums */
};

struct strip {
	int magic;
	/*
	 * These are pointers to the malloc()ed frame buffers.
	 */

	unsigned char *rx_buff;	/* buffer for received IP packet */
	unsigned char *sx_buff;	/* buffer for received serial data */
	int sx_count;		/* received serial data counter */
	int sx_size;		/* Serial buffer size           */
	unsigned char *tx_buff;	/* transmitter buffer           */
	unsigned char *tx_head;	/* pointer to next byte to XMIT */
	int tx_left;		/* bytes left in XMIT queue     */
	int tx_size;		/* Serial buffer size           */

	/*
	 * STRIP interface statistics.
	 */

	unsigned long rx_packets;	/* inbound frames counter       */
	unsigned long tx_packets;	/* outbound frames counter      */
	unsigned long rx_errors;	/* Parity, etc. errors          */
	unsigned long tx_errors;	/* Planned stuff                */
	unsigned long rx_dropped;	/* No memory for skb            */
	unsigned long tx_dropped;	/* When MTU change              */
	unsigned long rx_over_errors;	/* Frame bigger then STRIP buf. */

	unsigned long pps_timer;	/* Timer to determine pps       */
	unsigned long rx_pps_count;	/* Counter to determine pps     */
	unsigned long tx_pps_count;	/* Counter to determine pps     */
	unsigned long sx_pps_count;	/* Counter to determine pps     */
	unsigned long rx_average_pps;	/* rx packets per second * 8    */
	unsigned long tx_average_pps;	/* tx packets per second * 8    */
	unsigned long sx_average_pps;	/* sent packets per second * 8  */

#ifdef EXT_COUNTERS
	unsigned long rx_bytes;		/* total received bytes */
	unsigned long tx_bytes;		/* total received bytes */
	unsigned long rx_rbytes;	/* bytes thru radio i/f */
	unsigned long tx_rbytes;	/* bytes thru radio i/f */
	unsigned long rx_sbytes;	/* tot bytes thru serial i/f */
	unsigned long tx_sbytes;	/* tot bytes thru serial i/f */
	unsigned long rx_ebytes;	/* tot stat/err bytes */
	unsigned long tx_ebytes;	/* tot stat/err bytes */
#endif

	/*
	 * Internal variables.
	 */

	struct list_head  list;		/* Linked list of devices */

	int discard;			/* Set if serial error          */
	int working;			/* Is radio working correctly?  */
	int firmware_level;		/* Message structuring level    */
	int next_command;		/* Next periodic command        */
	unsigned int user_baud;		/* The user-selected baud rate  */
	int mtu;			/* Our mtu (to spot changes!)   */
	long watchdog_doprobe;		/* Next time to test the radio  */
	long watchdog_doreset;		/* Time to do next reset        */
	long gratuitous_arp;		/* Time to send next ARP refresh */
	long arp_interval;		/* Next ARP interval            */
	struct timer_list idle_timer;	/* For periodic wakeup calls    */
	MetricomAddress true_dev_addr;	/* True address of radio        */
	int manual_dev_addr;		/* Hack: See note below         */

	FirmwareVersion firmware_version;	/* The radio's firmware version */
	SerialNumber serial_number;	/* The radio's serial number    */
	BatteryVoltage battery_voltage;	/* The radio's battery voltage  */

	/*
	 * Other useful structures.
	 */

	struct tty_struct *tty;		/* ptr to TTY structure         */
	struct net_device *dev;		/* Our device structure         */

	/*
	 * Neighbour radio records
	 */

	MetricomNodeTable portables;
	MetricomNodeTable poletops;
};

/*
 * Note: manual_dev_addr hack
 * 
 * It is not possible to change the hardware address of a Metricom radio,
 * or to send packets with a user-specified hardware source address, thus
 * trying to manually set a hardware source address is a questionable
 * thing to do.  However, if the user *does* manually set the hardware
 * source address of a STRIP interface, then the kernel will believe it,
 * and use it in certain places. For example, the hardware address listed
 * by ifconfig will be the manual address, not the true one.
 * (Both addresses are listed in /proc/net/strip.)
 * Also, ARP packets will be sent out giving the user-specified address as
 * the source address, not the real address. This is dangerous, because
 * it means you won't receive any replies -- the ARP replies will go to
 * the specified address, which will be some other radio. The case where
 * this is useful is when that other radio is also connected to the same
 * machine. This allows you to connect a pair of radios to one machine,
 * and to use one exclusively for inbound traffic, and the other
 * exclusively for outbound traffic. Pretty neat, huh?
 * 
 * Here's the full procedure to set this up:
 * 
 * 1. "slattach" two interfaces, e.g. st0 for outgoing packets,
 *    and st1 for incoming packets
 * 
 * 2. "ifconfig" st0 (outbound radio) to have the hardware address
 *    which is the real hardware address of st1 (inbound radio).
 *    Now when it sends out packets, it will masquerade as st1, and
 *    replies will be sent to that radio, which is exactly what we want.
 * 
 * 3. Set the route table entry ("route add default ..." or
 *    "route add -net ...", as appropriate) to send packets via the st0
 *    interface (outbound radio). Do not add any route which sends packets
 *    out via the st1 interface -- that radio is for inbound traffic only.
 * 
 * 4. "ifconfig" st1 (inbound radio) to have hardware address zero.
 *    This tells the STRIP driver to "shut down" that interface and not
 *    send any packets through it. In particular, it stops sending the
 *    periodic gratuitous ARP packets that a STRIP interface normally sends.
 *    Also, when packets arrive on that interface, it will search the
 *    interface list to see if there is another interface who's manual
 *    hardware address matches its own real address (i.e. st0 in this
 *    example) and if so it will transfer ownership of the skbuff to
 *    that interface, so that it looks to the kernel as if the packet
 *    arrived on that interface. This is necessary because when the
 *    kernel sends an ARP packet on st0, it expects to get a reply on
 *    st0, and if it sees the reply come from st1 then it will ignore
 *    it (to be accurate, it puts the entry in the ARP table, but
 *    labelled in such a way that st0 can't use it).
 * 
 * Thanks to Petros Maniatis for coming up with the idea of splitting
 * inbound and outbound traffic between two interfaces, which turned
 * out to be really easy to implement, even if it is a bit of a hack.
 * 
 * Having set a manual address on an interface, you can restore it
 * to automatic operation (where the address is automatically kept
 * consistent with the real address of the radio) by setting a manual
 * address of all ones, e.g. "ifconfig st0 hw strip FFFFFFFFFFFF"
 * This 'turns off' manual override mode for the device address.
 * 
 * Note: The IEEE 802 headers reported in tcpdump will show the *real*
 * radio addresses the packets were sent and received from, so that you
 * can see what is really going on with packets, and which interfaces
 * they are really going through.
 */


/************************************************************************/
/* Constants								*/

/*
 * CommandString1 works on all radios
 * Other CommandStrings are only used with firmware that provides structured responses.
 * 
 * ats319=1 Enables Info message for node additions and deletions
 * ats319=2 Enables Info message for a new best node
 * ats319=4 Enables checksums
 * ats319=8 Enables ACK messages
 */

static const int MaxCommandStringLength = 32;
static const int CompatibilityCommand = 1;

static const char CommandString0[] = "*&COMMAND*ATS319=7";	/* Turn on checksums & info messages */
static const char CommandString1[] = "*&COMMAND*ATS305?";	/* Query radio name */
static const char CommandString2[] = "*&COMMAND*ATS325?";	/* Query battery voltage */
static const char CommandString3[] = "*&COMMAND*ATS300?";	/* Query version information */
static const char CommandString4[] = "*&COMMAND*ATS311?";	/* Query poletop list */
static const char CommandString5[] = "*&COMMAND*AT~LA";		/* Query portables list */
typedef struct {
	const char *string;
	long length;
} StringDescriptor;

static const StringDescriptor CommandString[] = {
	{CommandString0, sizeof(CommandString0) - 1},
	{CommandString1, sizeof(CommandString1) - 1},
	{CommandString2, sizeof(CommandString2) - 1},
	{CommandString3, sizeof(CommandString3) - 1},
	{CommandString4, sizeof(CommandString4) - 1},
	{CommandString5, sizeof(CommandString5) - 1}
};

#define GOT_ALL_RADIO_INFO(S)      \
    ((S)->firmware_version.c[0] && \
     (S)->battery_voltage.c[0]  && \
     memcmp(&(S)->true_dev_addr, zero_address.c, sizeof(zero_address)))

static const char hextable[16] = "0123456789ABCDEF";

static const MetricomAddress zero_address;
static const MetricomAddress broadcast_address =
    { {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF} };

static const MetricomKey SIP0Key = { "SIP0" };
static const MetricomKey ARP0Key = { "ARP0" };
static const MetricomKey ATR_Key = { "ATR " };
static const MetricomKey ACK_Key = { "ACK_" };
static const MetricomKey INF_Key = { "INF_" };
static const MetricomKey ERR_Key = { "ERR_" };

static const long MaxARPInterval = 60 * HZ;	/* One minute */