flow_cache.c

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/****************************************************************************
 *
 * Copyright (C) 2003-2008 Sourcefire, Inc.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License Version 2 as
 * published by the Free Software Foundation.  You may not use, modify or
 * distribute this program under any other version of the GNU General
 * Public License.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 ****************************************************************************/
 
/**
 * @file   flow_cache.c
 * @author Chris Green <[e-mail]>
 * @date   Fri Jun 20 09:04:51 2003
 * 
 * @brief  where flows are stored
 * 
 * The FlowCache is a memory-capped storage area for the FLOW
 * datatype.  It is inspired by spp_conversation, ipaudit, stream4 and
 * frag2. 
 *
 *
 * Each FLOW is uniquely identified by the 5-tuple (ipproto,sip,dip,sport,dport)
 *
 * Currently we only support IPV4 but new protocols will only require
 * the addition of additional protocol specific hash tables.  Ideally,
 * the API will stay the same and just do a switch on the key type to
 * support the various address families.
 *
 * This is meant to centralize the state management routines so that
 * it's easy to just worry about higher level protocols in other
 * modules.
 *
 * This is built on top of sfxhash currently and relies on it for
 * memory management. flow_hash.c contains the hashing keys 
 * 
 */
#define FLOW_PERF_FIX

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <stdio.h>

#include "flow_cache.h"
#include "flow_callback.h"
#include "flow_hash.h"
#include "bitop_funcs.h"
#include "sf_types.h"

/* helper functions */
static int flowcache_anrfree( void *key, void *data);
static int flowcache_usrfree( void *key, void *data);

/* minor optimization functions */
static INLINE int flowcache_mru(FLOWCACHE *flowcachep, FLOW **flowpp);
static INLINE int flowcache_lru(FLOWCACHE *flowcachep, FLOW **flowpp);

/* statistics functions */
static INLINE int FCS_find(FLOWCACHE *flowcachecp, FLOWKEY *keyp);
static INLINE int FCS_revfind(FLOWCACHE *flowcachecp, FLOWKEY *keyp);
static INLINE int FCS_new(FLOWCACHE *flowcachecp, FLOWKEY *keyp);
static INLINE int FCS_find_success(FLOWCACHE *flowcachecp, FLOWKEY *keyp);
static INLINE int FCS_find_fail(FLOWCACHE *flowcachecp, FLOWKEY *keyp);

int flowcache_init(FLOWCACHE *flowcachep, unsigned int rows,
                   int memcap, int datasize, FLOWHASHID hashid)
{
    int ret;
    int real_datasize = 0;
    
    if(!flowcachep)
    {
        return FLOW_ENULL;
    }

    if(datasize < 0)
    {
        return FLOW_ENULL;
    }

    if(memcap <= (int)(datasize + sizeof(FLOW) + sizeof(SFXHASH_NODE)))
    {
        /* come on man, you gotta give me enough memory to store 1. */
        return FLOW_EINVALID;
    }

    if(rows < 1)
        return FLOW_EINVALID;

    /* zero out the struct for all the additional data strctures */
    memset(flowcachep, 0, sizeof(FLOWCACHE));

    /*
    **  If we have a datasize, then we need to decrement by 1 because
    **  the FLOWDATA already has one byte.
    */
    if(datasize)
    {
        real_datasize = datasize - 1;
    }

    /*
    **  datasize-1 because there is already 1 byte in the FLOWDATA
    **  structure.
    */
    flowcachep->ipv4_table =
        sfxhash_new(rows,                         /* # of nodes in HT*/
                    sizeof(FLOWKEY),              /* size of the key  */
                    sizeof(FLOW) + real_datasize, /* data size */
                    memcap,                       /* max memory */
                    1,                            /* auto recover nodes */
                    flowcache_anrfree,            /* autorecovery function */
                    flowcache_usrfree,            /* data free function*/
                    1);                           /* recycle old nodes */

    if(flowcachep->ipv4_table == NULL)
    {
        return FLOW_ENOMEM;
    }

    /* set our hash function to something that understands ipv4 flowkeys */
    switch(hashid)
    {
    case HASH1:
        ret = sfxhash_set_keyops(flowcachep->ipv4_table,
                                 flowkey_hashfcn1,
                                 flowkeycmp_fcn);
        break;
    case HASH2:
        ret = sfxhash_set_keyops(flowcachep->ipv4_table,
                                 flowkey_hashfcn2,
                                 flowkeycmp_fcn);
        break;
    default:
        ret = FLOW_EINVALID;
    }

    /* if setting the hash function or setting the comparison function fails,
       abort */
    if(ret != 0)
    {
        sfxhash_delete(flowcachep->ipv4_table);
        return FLOW_BADJUJU;
    }

    flowcachep->max_flowbits_bytes = (unsigned int)datasize;

    return FLOW_SUCCESS;
}

int flowcache_destroy(FLOWCACHE *flowcachep)
{
    if(!flowcachep)
    {
        return FLOW_ENULL;
    }

    sfxhash_delete(flowcachep->ipv4_table);

    flowcachep->ipv4_table = NULL;
    
    return FLOW_SUCCESS;
}

unsigned flowcache_overhead_blocks(FLOWCACHE *fcp)
{
    return sfxhash_overhead_blocks(fcp->ipv4_table);
}


int flowcache_releaseflow(FLOWCACHE *flowcachep, FLOW **flowpp)
{
    FLOWKEY *key;
    FLOWKEY search_key;
    
    if(!flowcachep || !flowpp || !(*flowpp))
    {
        return FLOW_ENULL;
    }

    /** @todo remove any associated data with the flow */

    key = &(*flowpp)->key;
    
    flowkey_normalize(&search_key, key);

    if(sfxhash_remove(flowcachep->ipv4_table, &search_key) != 0)
    {
        return FLOW_NOTFOUND;
    }

    /* we've successfully removed the node from the table */
    
    *flowpp = NULL;

    return FLOW_SUCCESS;
}

int init_flowdata(FLOWCACHE *fcp, FLOW *flowp)
{
    if(!flowp || !fcp)
        return 1;

    if(boInitStaticBITOP(&(flowp->data.boFlowbits), fcp->max_flowbits_bytes, 
                         flowp->data.flowb))
    {
        return 1;
    }

    return 0;
}

int flowcache_newflow(FLOWCACHE *flowcachep, FLOWKEY *keyp, FLOW **flowpp)
{
    static int run_once = 1;
#ifdef FLOW_PERF_FIX
    FLOW *newflow = NULL;
    SFXHASH_NODE *new_node = NULL;
#else
    static FLOW zeroflow;
#endif
    static FLOWKEY searchkey;
    int ret;
    
    if(!flowcachep || !keyp || !flowpp)
    {
        return FLOW_ENULL;
    }

    FCS_new(flowcachep, keyp);
    
    if(run_once)
    {
        /* all the time that we're running this, we're actually going
           to be filling in the key, and having zero'd out counters */ 
#ifndef FLOW_PERF_FIX
        memset(&zeroflow, 0, sizeof(FLOW));
#endif
        memset(&searchkey, 0, sizeof(FLOWKEY));        
        run_once = 0;
    }

    flowkey_normalize(&searchkey, keyp);
   
#ifdef FLOW_PERF_FIX
    /* This just eliminates a memcpy. */
    /* Since we're using auto node recovery, we should get a node back
     * here that has a data pointer. */
    /* flow_init resets the internal key & stats to zero. */
    new_node = sfxhash_get_node(flowcachep->ipv4_table, &searchkey);
    if (new_node && new_node->data)
    {
        newflow = new_node->data;
    
        if(flow_init(newflow, keyp->protocol,
                     keyp->init_address, keyp->init_port,
                     keyp->resp_address, keyp->resp_port))
        {
            return FLOW_ENULL;
        }
        ret = SFXHASH_OK;
    }
    else
    {
        ret = SFXHASH_NOMEM;
    }
#else
    if(flow_init(&zeroflow, keyp->protocol,
                 keyp->init_address, keyp->init_port,
                 keyp->resp_address, keyp->resp_port))
    {
        return FLOW_ENULL;
    }

    ret = sfxhash_add(flowcachep->ipv4_table, &searchkey, &zeroflow);
#endif

    switch(ret)
    {
    case SFXHASH_OK:
        if(flowcache_mru(flowcachep,flowpp) != FLOW_SUCCESS)
        {
            /* something's wrong because we just added this thing!\n */
            flow_printf("Unable to find a key I just added!\n");
            return FLOW_BADJUJU;
        }

        if(init_flowdata(flowcachep, *flowpp))
        {
            return FLOW_BADJUJU;
        }

        return FLOW_SUCCESS;
        
    case SFXHASH_NOMEM:
        return FLOW_ENOMEM;

    case SFXHASH_INTABLE:
    default:
        return FLOW_EINVALID;
    }
}

/** 
 * Get the most recently used flow from the cache
 * 
 * @param flowcachep flow cache to operate on
 * @param flowp where to put the flow
 * 
 * @return FLOW_SUCCESS on success
 */
static INLINE int flowcache_mru(FLOWCACHE *flowcachep, FLOW **flowpp)
{
    if(!flowcachep  || !flowpp)
        return FLOW_EINVALID;

    *flowpp = sfxhash_mru(flowcachep->ipv4_table);

    if(*flowpp == NULL)
        return FLOW_NOTFOUND;