snoop.h

一种无线拥塞控制协议

/***************************************************************************
                          snoop.h  -  SNOOP HEADER
                             -------------------
    last updated         : March 25 2003
    copyright            : (C) 2002 by Indradeep Biswas
    email                : [e-mail]
 ***************************************************************************/

#ifndef SNOOP
#define SNOOP

//============ INCLUDE FILES - functions are imported from them ============

#include <linux/module.h>
#include <linux/skbuff.h>	// Definition of the SOCKET BUFFER
#include <linux/tcp.h>		// Definition of the TCP packet
#include <linux/ip.h>		// Definition of the IP packet
#include <linux/slab.h>		// Malloc function
#include <linux/time.h>		// Timekeeping header file
#include <linux/timer.h>	// Used for Timer functions
#include <linux/param.h>	// Converts strings to other formats & V.V
#include <linux/sched.h>	// Used for schedulilng
#include <asm/byteorder.h>
#include <asm/semaphore.h>
#include <net/tcp.h>
#include <asm/io.h>
//============ SNOOP CONTROL PARAMETERS ====================================

#define SNOOP_MAXWINDOW		20	// Max # of packets to cache per conn
#define SNOOP_MAXCONN		5	// Max # of connections to accept
#define SNOOP_MAX_RXMIT		2	// Max # of local retransmissions
#define SNOOP_CONN_TIMEOUT	40	// Max time in seconds before timeout 
#define SNOOP_RTO		30	// Default RTO set to 50 ms

//============ SNOOP ERRORS - define types of errors =======================

#define SNOOPE_SUCCESS		 0	// Integer return for success.
#define SNOOPE_NOTFOUND		-1	// Item is not found
#define SNOOPE_PKTFULL		-2	// Packet buffer is full
#define SNOOPE_CONFULL		-3	// Connection buffer is full
#define SNOOPE_NOMEM		-4	// Out of memory - can't allocate
#define SNOOPE_FORWARD		-5	// Forward packet without processing
#define SNOOPE_DROP		-6	// Drop the packet from stack

//============ SNOOP STATES - status bits ==================================

#define SNOOP_ACTIVE	0x01	// connection active
#define SNOOP_CLOSED	0x02	// connection closed
#define SNOOP_FULL	0x04	// snoop cache full
#define SNOOP_NOACK	0x08	// no ack seen yet
#define SNOOP_DUPACK	0x16	// one dupack received ack seen yet

//============ OTHER MISCELLANEOUS DEFINITINOS =============================

#define IPPROTO_TCP	6	// Protocol value in IP header for TCP
#define SNOOP_DEBUG 	0	// If set, debug statements will be printed

#define SNOOP_FH		1	// Segment from Fixed host
#define SNOOP_MH		0	// Segment from Mobile host

//============ BASIC TRAVERSAL FUNCTIONS ===================================

#define NEXT(i) (i + 1) % SNOOP_MAXWINDOW
#define PREV(i) (i == 0)? SNOOP_MAXWINDOW - 1 : i - 1

//============ snoop_packet : sk_buff wrapper ==============================

typedef struct snoop_packet {
	unsigned int	conn_id;	// stores the address of cs
	unsigned int	seq;		// sequence number pointer
	unsigned int	size;		// amount of actual TCP data
	unsigned long 	departure;	// time when packet leaves - jiffies
	unsigned char	num_rxmit;	// number of local rexmits
	struct sk_buff	*skb;		// skbuff chain of data
	struct snoop_socket *sock;	// snoop socket used to identify connection
	struct timer_list rexmit;	// retransmission timeout timer
	spinlock_t 	lock;		// mutual exclusion spinlock
	unsigned long 	irqflags;	// for the spinlock
} snoop_packet_t;

//============ conn_state : control and maintain each connection ===========

typedef struct conn_state{
	unsigned char	state;		// state of connection
	unsigned int	last_seq;	// first byte of last packet buffered
	unsigned int	last_ack;	// last byte recd. by mh for sure
	unsigned char 	tail;		// next pkt goes here
	unsigned char 	head;		// first unack'd pkt
	unsigned long	rto;		// retransmission timeout
	struct snoop_socket *sock;	// snoop socket
	struct timer_list timeout;	// times out the connection when idle.
	struct semaphore mutex;
	snoop_packet_t	*pkts[SNOOP_MAXWINDOW];// circular pointer array
} snoop_cs_t;

//============ controller : control structure for snoop module =============

typedef struct controller {
	unsigned short	num_connections;	// number of active connections
	snoop_cs_t *cstate[SNOOP_MAXCONN];	// array of per-connection state
} snoop_control_t;


//============ snoop_socket : a tcp socket for snoop =======================

struct snoop_socket {
	unsigned int 	daddr;	// destination ip address
        unsigned int 	saddr;	// source ip address
        unsigned short	dest;	// destination port number
        unsigned short	source;	// source port number
};

//============ snoop_flags : keeps the flags temporarily ===================


struct snoop_flags {
	 __u8	syn:1,	// syn flag for connection start
		ack:1,	// ack flag for acknowledgement
		fin:1,	// fin flag for finishing off a connection
		rst:1,	// rst flag for resetting connection
		others:4;	// other flags can be accomodated here
};

//============ snoop_buffer : a wrapper for skb ============================

struct snoop_buffer {
	struct sk_buff		*skb;	// pointer to the actual sk_buff
	struct snoop_socket	*sock;	// socket for the packet above
	struct snoop_flags	*flags;	// flags for the packet above

	unsigned int	seq;		// sequence number for the packet
	unsigned int	ack_seq;	// acknowledgement number
	unsigned int	size;		// size of the above packet
};

#endif

//============ MISCELLANEOUS DEFINITIONS ===================================

int (* snoop_ip_forward)(struct sk_buff *);//forward hook
int (* snoop_ip_forward_finish)(struct sk_buff *); // kernel symbol

snoop_control_t snoop_control;	// SNOOP module control structure

//============ snoop.c : FUNCTION LIST =====================================

void * snoop_malloc (int);
int snoop_init_control();
int snoop_init_conn(struct snoop_buffer *);
int snoop_data(struct snoop_buffer *, unsigned int);
int snoop_insert(unsigned int, struct snoop_buffer *);
int snoop_save_packet (snoop_packet_t *, struct snoop_buffer *, unsigned int);
int snoop_forward (struct sk_buff *, snoop_packet_t *);
int snoop_ack(struct snoop_buffer *, unsigned int);
void snoop_clean_buff (unsigned int, unsigned int);
void snoop_free_packet (snoop_packet_t *);
void snoop_clean_conn(unsigned int);
void snoop_clean_conrol();
int snoop_getconn(struct snoop_buffer *, char *);
void snoop_error (char, char[]);
int snoop_main(struct sk_buff *);
void snoop_free_skb (struct sk_buff * free_skb);
void snoop_conn_timeout (unsigned long);
void snoop_packet_retransmit(unsigned long);
void snoop_rto_calc (snoop_cs_t *, unsigned long );