util_funcs.c

开发snmp的开发包有两个开放的SNMP开发库

    oid             newname[MAX_OID_LEN];

    for (i = 0, rtest = 0;
         i < (int) vp->namelen && i < (int) (*length) && !rtest; i++) {
        if (name[i] != vp->name[i]) {
            if (name[i] < vp->name[i])
                rtest = -1;
            else
                rtest = 1;
        }
    }
    if (rtest > 0 ||
        (exact == 1
         && (rtest || (int) *length != (int) (vp->namelen + 1)))) {
        if (var_len)
            *var_len = 0;
        return MATCH_FAILED;
    }

    memset(newname, 0, sizeof(newname));

    if (((int) *length) <= (int) vp->namelen || rtest == -1) {
        memmove(newname, vp->name, (int) vp->namelen * sizeof(oid));
        newname[vp->namelen] = 1;
        *length = vp->namelen + 1;
    } else if (((int) *length) > (int) vp->namelen + 1) {       /* exact case checked earlier */
        *length = vp->namelen + 1;
        memmove(newname, name, (*length) * sizeof(oid));
        if (name[*length - 1] < ULONG_MAX) {
            newname[*length - 1] = name[*length - 1] + 1;
        } else {
            /*
             * Careful not to overflow...  
             */
            newname[*length - 1] = name[*length - 1];
        }
    } else {
        *length = vp->namelen + 1;
        memmove(newname, name, (*length) * sizeof(oid));
        if (!exact) {
            if (name[*length - 1] < ULONG_MAX) {
                newname[*length - 1] = name[*length - 1] + 1;
            } else {
                /*
                 * Careful not to overflow...  
                 */
                newname[*length - 1] = name[*length - 1];
            }
        } else {
            newname[*length - 1] = name[*length - 1];
        }
    }
    if ((max >= 0 && ((int)newname[*length - 1] > max)) ||
               ( 0 == newname[*length - 1] )) {
        if (var_len)
            *var_len = 0;
        return MATCH_FAILED;
    }

    memmove(name, newname, (*length) * sizeof(oid));
    if (write_method)
        *write_method = 0;
    if (var_len)
        *var_len = sizeof(long);        /* default */
    return (MATCH_SUCCEEDED);
}

/*
 * header_generic(...
 * Arguments:
 * vp     IN      - pointer to variable entry that points here
 * name    IN/OUT  - IN/name requested, OUT/name found
 * length  IN/OUT  - length of IN/OUT oid's 
 * exact   IN      - TRUE if an exact match was requested
 * var_len OUT     - length of variable or 0 if function returned
 * write_method
 * 
 */

/*******************************************************************-o-******
 * generic_header
 *
 * Parameters:
 *	  *vp	   (I)     Pointer to variable entry that points here.
 *	  *name	   (I/O)   Input name requested, output name found.
 *	  *length  (I/O)   Length of input and output oid's.
 *	   exact   (I)     TRUE if an exact match was requested.
 *	  *var_len (O)     Length of variable or 0 if function returned.
 *	(**write_method)   Hook to name a write method (UNUSED).
 *      
 * Returns:
 *	MATCH_SUCCEEDED	If vp->name matches name (accounting for exact bit).
 *	MATCH_FAILED	Otherwise,
 *
 *
 * Check whether variable (vp) matches name.
 */
int
header_generic(struct variable *vp,
               oid * name,
               size_t * length,
               int exact, size_t * var_len, WriteMethod ** write_method)
{
    oid             newname[MAX_OID_LEN];
    int             result;

    DEBUGMSGTL(("util_funcs", "header_generic: "));
    DEBUGMSGOID(("util_funcs", name, *length));
    DEBUGMSG(("util_funcs", " exact=%d\n", exact));

    memcpy((char *) newname, (char *) vp->name,
           (int) vp->namelen * sizeof(oid));
    newname[vp->namelen] = 0;
    result = snmp_oid_compare(name, *length, newname, vp->namelen + 1);
    DEBUGMSGTL(("util_funcs", "  result: %d\n", result));
    if ((exact && (result != 0)) || (!exact && (result >= 0)))
        return (MATCH_FAILED);
    memcpy((char *) name, (char *) newname,
           ((int) vp->namelen + 1) * sizeof(oid));
    *length = vp->namelen + 1;

    *write_method = 0;
    *var_len = sizeof(long);    /* default to 'long' results */
    return (MATCH_SUCCEEDED);
}

/*
 * checkmib(): provided for backwards compatibility, do not use: 
 */
int
checkmib(struct variable *vp, oid * name, size_t * length,
         int exact, size_t * var_len, WriteMethod ** write_method, int max)
{
    /*
     * checkmib used to be header_simple_table, with reveresed boolean
     * return output.  header_simple_table() was created to match
     * header_generic(). 
     */
    return (!header_simple_table(vp, name, length, exact, var_len,
                                 write_method, max));
}

char           *
find_field(char *ptr, int field)
{
    int             i;
    char           *init = ptr;

    if (field == NETSNMP_LASTFIELD) {
        /*
         * skip to end 
         */
        while (*ptr++);
        ptr = ptr - 2;
        /*
         * rewind a field length 
         */
        while (*ptr != 0 && isspace(*ptr) && init <= ptr)
            ptr--;
        while (*ptr != 0 && !isspace(*ptr) && init <= ptr)
            ptr--;
        if (isspace(*ptr))
            ptr++;              /* past space */
        if (ptr < init)
            ptr = init;
        if (!isspace(*ptr) && *ptr != 0)
            return (ptr);
    } else {
        if ((ptr = skip_white(ptr)) == NULL)
            return (NULL);
        for (i = 1; *ptr != 0 && i != field; i++) {
            if ((ptr = skip_not_white(ptr)) == NULL)
                return (NULL);
            if ((ptr = skip_white(ptr)) == NULL)
                return (NULL);
        }
        if (*ptr != 0 && i == field)
            return (ptr);
        return (NULL);
    }
    return (NULL);
}

int
parse_miboid(const char *buf, oid * oidout)
{
    int             i;

    if (!buf)
        return 0;
    if (*buf == '.')
        buf++;
    for (i = 0; isdigit(*buf); i++) {
        oidout[i] = atoi(buf);
        while (isdigit(*buf++));
        if (*buf == '.')
            buf++;
    }
    /*
     * oidout[i] = -1; hmmm 
     */
    return i;
}

void
string_append_int(char *s, int val)
{
    char            textVal[16];

    if (val < 10) {
        *s++ = '0' + val;
        *s = '\0';
        return;
    }
    sprintf(textVal, "%d", val);
    strcpy(s, textVal);
    return;
}

struct internal_mib_table {
    int             max_size;   /* Size of the current data table */
    int             next_index; /* Index of the next free entry */
    int             current_index;      /* Index of the 'current' entry */
    int             cache_timeout;
    marker_t        cache_marker;
    RELOAD         *reload;     /* Routine to read in the data */
    COMPARE        *compare;    /* Routine to compare two entries */
    int             data_size;  /* Size of an individual entry */
    void           *data;       /* The table itself */
};

mib_table_t
Initialise_Table(int size, int timeout, RELOAD *reload, COMPARE *compare)
{
    struct internal_mib_table *t;

    t = (struct internal_mib_table *)
        malloc(sizeof(struct internal_mib_table));
    if (t == NULL)
        return NULL;

    t->max_size = 0;
    t->next_index = 1;          /* Don't use index 0 */
    t->current_index = 1;
    t->cache_timeout = timeout;
    t->cache_marker = NULL;
    t->reload = reload;
    t->compare = compare;
    t->data_size = size;
    t->data = NULL;

    return (mib_table_t) t;
}

#define TABLE_ADD( x, y )	((void*)((char*)(x) + y))
#define TABLE_INDEX(t, i)	(TABLE_ADD(t->data, i * t->data_size))
#define TABLE_START(t)		(TABLE_INDEX(t, 1))
#define TABLE_NEXT(t)		(TABLE_INDEX(t, t->next_index))
#define TABLE_CURRENT(t)	(TABLE_INDEX(t, t->current_index))

int
check_and_reload_table(struct internal_mib_table *table)
{
    /*
     * If the saved data is fairly recent,
     *    we don't need to reload it
     */
    if (table->cache_marker &&
        !(atime_ready(table->cache_marker, table->cache_timeout * 1000)))
        return 1;


    /*
     * Call the routine provided to read in the data
     *
     * N.B:  Update the cache marker *before* calling
     *   this routine, to avoid problems with recursion
     */
    if (!table->cache_marker)
        table->cache_marker = atime_newMarker();
    else
        atime_setMarker(table->cache_marker);

    table->next_index = 1;
    if (table->reload((mib_table_t) table) < 0) {
        free(table->cache_marker);
        table->cache_marker = NULL;
        return 0;
    }
    table->current_index = 1;
    if (table->compare != NULL) /* Sort the table */
        qsort(TABLE_START(table), table->next_index,
              table->data_size, table->compare);
    return 1;
}

int
Search_Table(mib_table_t t, void *entry, int exact)
{
    struct internal_mib_table *table = (struct internal_mib_table *) t;
    void           *entry2;
    int             res;

    if (!check_and_reload_table(table))
        return -1;

    if (table->compare == NULL) {
        /*
         * XXX - not sure this is right ? 
         */
        memcpy(entry, table->data, table->data_size);
        return 0;
    }

    if (table->next_index == table->current_index)
        table->current_index = 1;

    entry2 = TABLE_CURRENT(table);
    res = table->compare(entry, entry2);
    if ((res < 0) && (table->current_index != 1)) {
        table->current_index = 1;
        entry2 = TABLE_CURRENT(table);
        res = table->compare(entry, entry2);
    }

    while (res > 0) {
        table->current_index++;
        if (table->next_index == table->current_index)
            return -1;
        entry2 = TABLE_CURRENT(table);
        res = table->compare(entry, entry2);
    }

    if (exact && res != 0)
        return -1;

    if (!exact && res == 0) {
        table->current_index++;
        if (table->next_index == table->current_index)
            return -1;
        entry2 = TABLE_CURRENT(table);
    }
    memcpy(entry, entry2, table->data_size);
    return 0;
}

int
Add_Entry(mib_table_t t, void *entry)
{
    struct internal_mib_table *table = (struct internal_mib_table *) t;
    int             new_max;
    void           *new_data;   /* Used for
                                 *      a) extending the data table
                                 *      b) the next entry to use
                                 */

    if (table->max_size <= table->next_index) {
        /*
         * Table is full, so extend it to double the size
         */
        new_max = 2 * table->max_size;
        if (new_max == 0)
            new_max = 10;       /* Start with 10 entries */

        new_data = (void *) malloc(new_max * table->data_size);
        if (new_data == NULL)
            return -1;

        if (table->data) {
            memcpy(new_data, table->data,
                   table->max_size * table->data_size);
            free(table->data);
        }
        table->data = new_data;
        table->max_size = new_max;
    }

    /*
     * Insert the new entry into the data array
     */
    new_data = TABLE_NEXT(table);
    memcpy(new_data, entry, table->data_size);
    table->next_index++;
    return 0;
}

void           *
Retrieve_Table_Data(mib_table_t t, int *max_idx)
{
    struct internal_mib_table *table = (struct internal_mib_table *) t;

    if (!check_and_reload_table(table))
        return NULL;
    *max_idx = table->next_index - 1;
    return table->data;
}