iftable_data_access.c

开发snmp的开发包有两个开放的SNMP开发库

/*
 * Note: this file originally auto-generated by mib2c using
 *       version : 1.17 $ of : mfd-data-access.m2c,v $ 
 *
 * $Id: ifTable_data_access.c 15814 2007-02-05 15:10:28Z rstory $
 */
/*
 * standard Net-SNMP includes 
 */
#include <net-snmp/net-snmp-config.h>
#include <net-snmp/net-snmp-includes.h>
#include <net-snmp/agent/net-snmp-agent-includes.h>

/*
 * include our parent header 
 */
#include "ifTable.h"
#include "ifTable_defs.h"

#include "ifTable_data_access.h"

#ifdef USING_IP_MIB_IPV4INTERFACETABLE_IPV4INTERFACETABLE_MODULE
#   include "mibgroup/ip-mib/ipv4InterfaceTable/ipv4InterfaceTable.h"
#endif

/*
 * flag so we know not to set row/table last change times
 * during startup.
 */
static int      _first_load = 1;

/** @ingroup interface 
 * @defgroup data_access data_access: Routines to access data
 *
 * These routines are used to locate the data used to satisfy
 * requests.
 * 
 * @{
 */
/**********************************************************************
 **********************************************************************
 ***
 *** Table ifTable
 ***
 **********************************************************************
 **********************************************************************/
/*
 * IF-MIB::ifTable is subid 2 of interfaces.
 * Its status is Current.
 * OID: .1.3.6.1.2.1.2.2, length: 8
 */

/**
 * initialization for ifTable data access
 *
 * This function is called during startup to allow you to
 * allocate any resources you need for the data table.
 *
 * @param ifTable_reg
 *        Pointer to ifTable_registration
 *
 * @retval MFD_SUCCESS : success.
 * @retval MFD_ERROR   : unrecoverable error.
 */
int
ifTable_init_data(ifTable_registration * ifTable_reg)
{
    DEBUGMSGTL(("verbose:ifTable:ifTable_init_data", "called\n"));

    /*
     * TODO:303:o: Initialize ifTable data.
     */

    return MFD_SUCCESS;
}                               /* ifTable_init_data */

/**
 * container overview
 *
 */

/**
 * container initialization
 *
 * @param container_ptr_ptr A pointer to a container pointer. If you
 *        create a custom container, use this parameter to return it
 *        to the MFD helper. If set to NULL, the MFD helper will
 *        allocate a container for you.
 * @param  cache A pointer to a cache structure. You can set the timeout
 *         and other cache flags using this pointer.
 *
 *  This function is called at startup to allow you to customize certain
 *  aspects of the access method. For the most part, it is for advanced
 *  users. The default code should suffice for most cases. If no custom
 *  container is allocated, the MFD code will create one for your.
 *
 *  This is also the place to set up cache behavior. The default, to
 *  simply set the cache timeout, will work well with the default
 *  container. If you are using a custom container, you may want to
 *  look at the cache helper documentation to see if there are any
 *  flags you want to set.
 *
 * @remark
 *  This would also be a good place to do any initialization needed
 *  for you data source. For example, opening a connection to another
 *  process that will supply the data, opening a database, etc.
 */
void
ifTable_container_init(netsnmp_container **container_ptr_ptr,
                       netsnmp_cache * cache)
{
    DEBUGMSGTL(("verbose:ifTable:ifTable_container_init", "called\n"));

    if (NULL == container_ptr_ptr) {
        snmp_log(LOG_ERR,
                 "bad container param to ifTable_container_init\n");
        return;
    }

    /*
     * For advanced users, you can use a custom container. If you
     * do not create one, one will be created for you.
     */
    *container_ptr_ptr = NULL;

    if (NULL == cache) {
        snmp_log(LOG_ERR, "bad cache param to ifTable_container_init\n");
        return;
    }

    /*
     * TODO:345:A: Set up ifTable cache properties.
     *
     * Also for advanced users, you can set parameters for the
     * cache. Do not change the magic pointer, as it is used
     * by the MFD helper. To completely disable caching, set
     * cache->enabled to 0.
     */
    /*
     * since we set AUTO_RELOAD below, this timer controls how
     * often the cache is reloaded. A 10 Mbps stream can wrap if*Octets in ~57 minutes.
     * At 100 Mbps it is ~5 minutes, and at 1 Gbps, ~34 seconds.
     */
    cache->timeout = IFTABLE_CACHE_TIMEOUT;     /* seconds */

    /*
     * don't release resources
     */
    cache->flags |=
        (NETSNMP_CACHE_DONT_AUTO_RELEASE | NETSNMP_CACHE_DONT_FREE_EXPIRED
         | NETSNMP_CACHE_DONT_FREE_BEFORE_LOAD | NETSNMP_CACHE_PRELOAD |
         NETSNMP_CACHE_AUTO_RELOAD | NETSNMP_CACHE_DONT_INVALIDATE_ON_SET);
}                               /* ifTable_container_init */

/**
 * check entry for update
 *
 */
static void
_check_interface_entry_for_updates(ifTable_rowreq_ctx * rowreq_ctx,
                                   netsnmp_container *ifcontainer)
{
    char            oper_changed = 0;

    /*
     * check for matching entry. We can do this directly, since
     * both containers use the same index.
     */
    netsnmp_interface_entry *ifentry =
        CONTAINER_FIND(ifcontainer, rowreq_ctx);

#ifdef USING_IP_MIB_IPV4INTERFACETABLE_IPV4INTERFACETABLE_MODULE
    /*
     * give ipv4If table a crack at the entry
     */
    ipv4InterfaceTable_check_entry_for_updates(rowreq_ctx, ifentry);
#endif

#ifdef USING_IP_MIB_IPV6INTERFACETABLE_IPV6INTERFACETABLE_MODULE
    /*
     * give ipv6If table a crack at the entry
     */
    ipv6InterfaceTable_check_entry_for_updates(rowreq_ctx, ifentry);
#endif

    if (NULL == ifentry) {
        /*
         * if this is the first time we detected that this interface is
         * missing, set admin/oper status down, and set last change.
         *
         * yyy-rks: when, if ever, would we consider an entry
         * deleted (and thus need to update ifTableLastChanged)?
         */
        if (!rowreq_ctx->known_missing) {
            DEBUGMSGTL(("ifTable:access", "updating missing entry\n"));
            rowreq_ctx->known_missing = 1;
            rowreq_ctx->data.ifAdminStatus = IFADMINSTATUS_DOWN;
            if ((!(rowreq_ctx->data.ifentry->ns_flags & NETSNMP_INTERFACE_FLAGS_HAS_LASTCHANGE))
                && (rowreq_ctx->data.ifOperStatus != IFOPERSTATUS_DOWN))
                oper_changed = 1;
            rowreq_ctx->data.ifOperStatus = IFOPERSTATUS_DOWN;
        }
    } else {
        DEBUGMSGTL(("ifTable:access", "updating existing entry\n"));

#ifdef USING_IF_MIB_IFXTABLE_IFXTABLE_MODULE
        {
            int rc = strcmp(rowreq_ctx->data.ifName,
                            ifentry->name);
            netsnmp_assert(rc == 0);
        }
#endif
        /*
         * if the interface was missing, but came back, clear the
         * missing flag and set the discontinuity time. (if an os keeps
         * persistent counters, tough cookies. We'll cross that 
         * bridge if we come to it).
         */
        if (rowreq_ctx->known_missing) {
            rowreq_ctx->known_missing = 0;
#ifdef USING_IF_MIB_IFXTABLE_IFXTABLE_MODULE
            rowreq_ctx->data.ifCounterDiscontinuityTime =
                netsnmp_get_agent_uptime();
#endif
        }

        /*
         * Check for changes, then update
         */
        if ((!(ifentry->ns_flags & NETSNMP_INTERFACE_FLAGS_HAS_LASTCHANGE))
            && (rowreq_ctx->data.ifOperStatus != ifentry->oper_status))
            oper_changed = 1;
        netsnmp_access_interface_entry_copy(rowreq_ctx->data.ifentry,
                                            ifentry);

        /*
         * remove entry from temporary ifcontainer
         */
        CONTAINER_REMOVE(ifcontainer, ifentry);
        netsnmp_access_interface_entry_free(ifentry);
    }

    /*
     * if ifOperStatus changed, update ifLastChange
     */
    if (oper_changed)
        rowreq_ctx->data.ifLastChange = netsnmp_get_agent_uptime();

}

/**
 * add new entry
 */
static void
_add_new_interface(netsnmp_interface_entry *ifentry,
                   netsnmp_container *container)
{
    ifTable_rowreq_ctx *rowreq_ctx;

    DEBUGMSGTL(("ifTable:access", "creating new entry\n"));

    /*
     * allocate an row context and set the index(es), then add it to
     * the container and set ifTableLastChanged.
     */
    rowreq_ctx = ifTable_allocate_rowreq_ctx(ifentry);
    if ((NULL != rowreq_ctx) &&
        (MFD_SUCCESS == ifTable_indexes_set(rowreq_ctx, ifentry->index))) {
        CONTAINER_INSERT(container, rowreq_ctx);
        /*
         * fix this when we hit an arch that reports its own last change
         */
        netsnmp_assert(0 == (ifentry->ns_flags &
                             NETSNMP_INTERFACE_FLAGS_HAS_LASTCHANGE));
        if (0 == _first_load) {
            rowreq_ctx->data.ifLastChange = netsnmp_get_agent_uptime();
            ifTable_lastChange_set(rowreq_ctx->data.ifLastChange);
        }
#ifdef USING_IP_MIB_IPV4INTERFACETABLE_IPV4INTERFACETABLE_MODULE
        /*
         * give ipv4If table a crack at the entry
         */
        ipv4InterfaceTable_check_entry_for_updates(rowreq_ctx, ifentry);
#endif
#ifdef USING_IP_MIB_IPV6INTERFACETABLE_IPV6INTERFACETABLE_MODULE
        /*
         * give ipv6If table a crack at the entry
         */
        ipv6InterfaceTable_check_entry_for_updates(rowreq_ctx, ifentry);
#endif
    } else {
        if (rowreq_ctx) {
            snmp_log(LOG_ERR, "error setting index while loading "
                     "ifTable cache.\n");
            ifTable_release_rowreq_ctx(rowreq_ctx);
        } else {
            snmp_log(LOG_ERR, "memory allocation failed while loading "
                     "ifTable cache.\n");
            netsnmp_access_interface_entry_free(ifentry);
        }
    }
}

/**
 * container shutdown
 *
 * @param container_ptr A pointer to the container.
 *
 *  This function is called at shutdown to allow you to customize certain
 *  aspects of the access method. For the most part, it is for advanced
 *  users. The default code should suffice for most cases.
 *
 *  This function is called before ifTable_container_free().
 *
 * @remark
 *  This would also be a good place to do any cleanup needed
 *  for you data source. For example, closing a connection to another
 *  process that supplied the data, closing a database, etc.
 */
void
ifTable_container_shutdown(netsnmp_container *container_ptr)
{
    DEBUGMSGTL(("verbose:ifTable:ifTable_container_shutdown", "called\n"));

    if (NULL == container_ptr) {
        snmp_log(LOG_ERR, "bad params to ifTable_container_shutdown\n");
        return;
    }

}                               /* ifTable_container_shutdown */

/**
 * load initial data
 *
 * TODO:350:M: Implement ifTable data load
 * This function will also be called by the cache helper to load
 * the container again (after the container free function has been
 * called to free the previous contents).
 *
 * @param container container to which items should be inserted
 *
 * @retval MFD_SUCCESS              : success.
 * @retval MFD_RESOURCE_UNAVAILABLE : Can't access data source
 * @retval MFD_ERROR                : other error.
 *
 *  This function is called to load the index(es) (and data, optionally)
 *  for the every row in the data set.
 *
 * @remark
 *  While loading the data, the only important thing is the indexes.
 *  If access to your data is cheap/fast (e.g. you have a pointer to a
 *  structure in memory), it would make sense to update the data here.
 *  If, however, the accessing the data invovles more work (e.g. parsing
 *  some other existing data, or peforming calculations to derive the data),
 *  then you can limit yourself to setting the indexes and saving any
 *  information you will need later. Then use the saved information in
 *  ifTable_row_prep() for populating data.
 *
 * @note
 *  If you need consistency between rows (like you want statistics
 *  for each row to be from the same time frame), you should set all
 *  data here.
 *
 */
int
ifTable_container_load(netsnmp_container *container)
{
    netsnmp_container *ifcontainer;

    DEBUGMSGTL(("verbose:ifTable:ifTable_container_load", "called\n"));

    /*
     * TODO:351:M: |-> Load/update data in the ifTable container.
     * loop over your ifTable data, allocate a rowreq context,
     * set the index(es) [and data, optionally] and insert into
     * the container.
     */
    /*
     * ifTable gets its data from the netsnmp_interface API.
     */
    ifcontainer =
        netsnmp_access_interface_container_load(NULL,
                                                NETSNMP_ACCESS_INTERFACE_INIT_NOFLAGS);
    if (NULL == ifcontainer)
        return MFD_RESOURCE_UNAVAILABLE;        /* msg already logged */

    /*
     * we just got a fresh copy of interface data. compare it to
     * what we've already got, and make any adjustements...
     */
    CONTAINER_FOR_EACH(container, (netsnmp_container_obj_func *)
                       _check_interface_entry_for_updates, ifcontainer);

    /*
     * now add any new interfaces
     */
    CONTAINER_FOR_EACH(ifcontainer,
                       (netsnmp_container_obj_func *) _add_new_interface,
                       container);

    /*
     * free the container. we've either claimed each ifentry, or released it,
     * so the dal function doesn't need to clear the container.
     */
    netsnmp_access_interface_container_free(ifcontainer,
                                            NETSNMP_ACCESS_INTERFACE_FREE_DONT_CLEAR);

    DEBUGMSGT(("verbose:ifTable:ifTable_cache_load",
               "%d records\n", CONTAINER_SIZE(container)));

    if (_first_load)
        _first_load = 0;

    return MFD_SUCCESS;
}                               /* ifTable_container_load */

/**
 * container clean up
 *
 * @param container container with all current items
 *
 *  This optional callback is called prior to all
 *  item's being removed from the container. If you
 *  need to do any processing before that, do it here.
 *
 * @note
 *  The MFD helper will take care of releasing all the row contexts.
 *
 */
void
ifTable_container_free(netsnmp_container *container)
{
    DEBUGMSGTL(("verbose:ifTable:ifTable_container_free", "called\n"));

    /*
     * TODO:380:M: Free ifTable container data.
     */
}                               /* ifTable_container_free */

/**
 * prepare row for processing.
 *
 *  When the agent has located the row for a request, this function is
 *  called to prepare the row for processing. If you fully populated
 *  the data context during the index setup phase, you may not need to
 *  do anything.
 *
 * @param rowreq_ctx pointer to a context.
 *
 * @retval MFD_SUCCESS     : success.
 * @retval MFD_ERROR       : other error.
 */
int
ifTable_row_prep(ifTable_rowreq_ctx * rowreq_ctx)
{
    DEBUGMSGTL(("verbose:ifTable:ifTable_row_prep", "called\n"));

    netsnmp_assert(NULL != rowreq_ctx);

    /*
     * TODO:390:o: Prepare row for request.
     * If populating row data was delayed, this is the place to
     * fill in the row for this request.
     */

    return MFD_SUCCESS;
}                               /* ifTable_row_prep */

/** @} */