APPS/libalias/alias_mod.h

/*-
 * Copyright (c) 2005 Paolo Pisati <piso@FreeBSD.org>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * $FreeBSD: src/sys/netinet/libalias/alias_mod.h,v 1.1 2006/09/26 23:26:53 piso Exp $
 */

/*
 * Alias_mod.h defines the outside world interfaces for the packet aliasing
 * modular framework
 */

#ifndef _ALIAS_MOD_H_
#define _ALIAS_MOD_H_

#ifdef _KERNEL
MALLOC_DECLARE(M_ALIAS);

/* Use kernel allocator. */
#if defined(_SYS_MALLOC_H_)
#define	malloc(x)	malloc(x, M_ALIAS, M_NOWAIT|M_ZERO)
#define	calloc(x, n)	malloc(x*n)
#define	free(x)		free(x, M_ALIAS)
#endif
#endif

/* Protocol handlers struct & function. */

/* Packet flow direction. */
#define IN                              1 
#define OUT                             2 

/* Working protocol. */
#define IP                              1
#define TCP                             2
#define UDP                             4

/* 
 * Data passed to protocol handler module, it must be filled
 * right before calling find_handler() to determine which
 * module is elegible to be called.
 */

struct alias_data {	
	struct alias_link       *lnk;            
	struct in_addr          *oaddr;         /* Original address. */
	struct in_addr          *aaddr;         /* Alias address. */ 
	uint16_t                *aport;         /* Alias port. */
	uint16_t                *sport, *dport;	/* Source & destination port */
	uint16_t                maxpktsize;     /* Max packet size. */
}; 

/* 
 * This structure contains all the information necessary to make
 * a protocol handler correctly work.
 */

struct proto_handler {
	u_int pri;                                              /* Handler priority. */
        int16_t dir;                                            /* Flow direction. */
	uint8_t proto;                                          /* Working protocol. */	
	int (*fingerprint)(struct libalias *la,                 /* Fingerprint * function. */
		 struct ip *pip, struct alias_data *ah);
	int (*protohandler)(struct libalias *la,                /* Aliasing * function. */
		 struct ip *pip, struct alias_data *ah);                 
	LIST_ENTRY(proto_handler) entries;
};


/* 
 * Used only in userland when libalias needs to keep track of all
 * module loaded. In kernel land (kld mode) we don't need to care
 * care about libalias modules cause it's kld to do it for us.
 */

#define DLL_LEN         32
struct dll {	
	char            name[DLL_LEN];  /* Name of module. */
	void            *handle;        /* 
					 * Ptr to shared obj obtained through
					 * dlopen() - use this ptr to get access
					 * to any symbols from a loaded module 					 
					 * via dlsym(). 
					 */
	SLIST_ENTRY(dll)        next;
};

/* Functions used with protocol handlers. */

void            handler_chain_init(void);
void            handler_chain_destroy(void);
int             LibAliasAttachHandlers(struct proto_handler *);
int             LibAliasDetachHandlers(struct proto_handler *);
int             detach_handler(struct proto_handler *);
int             find_handler(int8_t, int8_t, struct libalias *, 
			   struct ip *, struct alias_data *);
struct proto_handler *first_handler(void);

/* Functions used with dll module. */

void            dll_chain_init(void);
void            dll_chain_destroy(void);
int             attach_dll(struct dll *);
void            *detach_dll(char *);
struct dll      *walk_dll_chain(void);

/* End of handlers. */
#define EOH     -1

/* 
 * Some defines borrowed from sys/module.h used to compile a kld
 * in userland as a shared lib.
 */

#ifndef _KERNEL
typedef enum modeventtype {
        MOD_LOAD,
        MOD_UNLOAD,
        MOD_SHUTDOWN,
        MOD_QUIESCE
} modeventtype_t;
        
typedef struct module *module_t;
typedef int (*modeventhand_t)(module_t, int /* modeventtype_t */, void *);

/*
 * Struct for registering modules statically via SYSINIT.
 */
typedef struct moduledata {
        const char      *name;          /* module name */
        modeventhand_t  evhand;         /* event handler */
        void            *priv;          /* extra data */
} moduledata_t;
#endif

#endif				/* !_ALIAS_MOD_H_ */