table_data.c

snmp的源代码,已经在我的ubuntu下编译通过

                regresult = -1;

            if (result < 0 || 0 == result) {
                /*
                 * before us entirely, return the first 
                 */
                row = table->first_row;
                table_info->colnum = table_reg_info->min_column;
            } else if (regresult == 0 && request->requestvb->name_length ==
                       reginfo->rootoid_len + 1 &&
                       /* entry node must be 1, but any column is ok */
                       request->requestvb->name[reginfo->rootoid_len] == 1) {
                /*
                 * exactly to the entry 
                 */
                row = table->first_row;
                table_info->colnum = table_reg_info->min_column;
            } else if (regresult == 0 && request->requestvb->name_length ==
                       reginfo->rootoid_len + 2 &&
                       /* entry node must be 1, but any column is ok */
                       request->requestvb->name[reginfo->rootoid_len] == 1) {
                /*
                 * exactly to the column 
                 */
                row = table->first_row;
            } else {
                /*
                 * loop through all rows looking for the first one
                 * that is equal to the request or greater than it 
                 */
                for (row = table->first_row; row; row = row->next) {
                    /*
                     * compare the index of the request to the row 
                     */
                    result =
                        snmp_oid_compare(row->index_oid,
                                         row->index_oid_len,
                                         request->requestvb->name + 2 +
                                         reginfo->rootoid_len,
                                         request->requestvb->name_length -
                                         2 - reginfo->rootoid_len);
                    if (result == 0) {
                        /*
                         * equal match, return the next row 
                         */
                        if (row) {
                            row = row->next;
                        }
                        break;
                    } else if (result > 0) {
                        /*
                         * the current row is greater than the
                         * request, use it 
                         */
                        break;
                    }
                }
            }
            if (!row) {
                table_info->colnum++;
                if (table_info->colnum <= table_reg_info->max_column) {
                    row = table->first_row;
                }
            }
            if (row) {
                valid_request = 1;
                netsnmp_request_add_list_data(request,
                                              netsnmp_create_data_list
                                              (TABLE_DATA_ROW, row,
                                               NULL));
                /*
                 * Set the name appropriately, so we can pass this
                 *  request on as a simple GET request
                 */
                netsnmp_table_data_build_result(reginfo, reqinfo, request,
                                                row,
                                                table_info->colnum,
                                                ASN_NULL, NULL, 0);
            } else {            /* no decent result found.  Give up. It's beyond us. */
                request->processed = 1;
            }
            break;

        case MODE_GET:
            if (request->requestvb->type != ASN_NULL)
                continue;
            /*
             * find the row in question 
             */
            if (request->requestvb->name_length < (reginfo->rootoid_len + 3)) { /* table.entry.column... */
                /*
                 * request too short 
                 */
                netsnmp_set_request_error(reqinfo, request,
                                          SNMP_NOSUCHINSTANCE);
                break;
            } else if (NULL ==
                       (row =
                        netsnmp_table_data_get_from_oid(table,
                                                        request->
                                                        requestvb->name +
                                                        reginfo->
                                                        rootoid_len + 2,
                                                        request->
                                                        requestvb->
                                                        name_length -
                                                        reginfo->
                                                        rootoid_len -
                                                        2))) {
                /*
                 * no such row 
                 */
                netsnmp_set_request_error(reqinfo, request,
                                          SNMP_NOSUCHINSTANCE);
                break;
            } else {
                valid_request = 1;
                netsnmp_request_add_list_data(request,
                                              netsnmp_create_data_list
                                              (TABLE_DATA_ROW, row,
                                               NULL));
            }
            break;

        case MODE_SET_RESERVE1:
            valid_request = 1;
            if (NULL !=
                (row =
                 netsnmp_table_data_get_from_oid(table,
                                                 request->requestvb->name +
                                                 reginfo->rootoid_len + 2,
                                                 request->requestvb->
                                                 name_length -
                                                 reginfo->rootoid_len -
                                                 2))) {
                netsnmp_request_add_list_data(request,
                                              netsnmp_create_data_list
                                              (TABLE_DATA_ROW, row,
                                               NULL));
            }
            break;

        case MODE_SET_RESERVE2:
        case MODE_SET_ACTION:
        case MODE_SET_COMMIT:
        case MODE_SET_FREE:
        case MODE_SET_UNDO:
            valid_request = 1;

        }
    }

    if (valid_request &&
       (reqinfo->mode == MODE_GETNEXT || reqinfo->mode == MODE_GETBULK)) {
        /*
         * If this is a GetNext or GetBulk request, then we've identified
         *  the row that ought to include the appropriate next instance.
         *  Convert the request into a Get request, so that the lower-level
         *  handlers don't need to worry about skipping on, and call these
         *  handlers ourselves (so we can undo this again afterwards).
         */
        oldmode = reqinfo->mode;
        reqinfo->mode = MODE_GET;
        result = netsnmp_call_next_handler(handler, reginfo, reqinfo,
                                         requests);
        reqinfo->mode = oldmode;
        handler->flags |= MIB_HANDLER_AUTO_NEXT_OVERRIDE_ONCE;
        return result;
    }
    else
        /* next handler called automatically - 'AUTO_NEXT' */
        return SNMP_ERR_NOERROR;
}

/** creates and returns a pointer to table data set */
netsnmp_table_data *
netsnmp_create_table_data(const char *name)
{
    netsnmp_table_data *table = SNMP_MALLOC_TYPEDEF(netsnmp_table_data);
    if (name && table)
        table->name = strdup(name);
    return table;
}

/** creates and returns a pointer to table data set */
netsnmp_table_row *
netsnmp_create_table_data_row(void)
{
    netsnmp_table_row *row = SNMP_MALLOC_TYPEDEF(netsnmp_table_row);
    return row;
}

/** inserts a newly created table_data row into a request */
NETSNMP_INLINE void
netsnmp_insert_table_row(netsnmp_request_info *request,
                         netsnmp_table_row *row)
{
    netsnmp_request_info       *req;
    netsnmp_table_request_info *table_info = NULL;
    netsnmp_variable_list      *this_index = NULL;
    netsnmp_variable_list      *that_index = NULL;
    oid      base_oid[] = {0, 0};	/* Make sure index OIDs are legal! */
    oid      this_oid[MAX_OID_LEN];
    oid      that_oid[MAX_OID_LEN];
    size_t   this_oid_len, that_oid_len;

    if (!request)
        return;

    /*
     * We'll add the new row information to any request
     * structure with the same index values as the request
     * passed in (which includes that one!).
     *
     * So construct an OID based on these index values.
     */

    table_info = netsnmp_extract_table_info(request);
    this_index = table_info->indexes;
    build_oid_noalloc(this_oid, MAX_OID_LEN, &this_oid_len,
                      base_oid, 2, this_index);

    /*
     * We need to look through the whole of the request list
     * (as received by the current handler), as there's no
     * guarantee that this routine will be called by the first
     * varbind that refers to this row.
     *   In particular, a RowStatus controlled row creation
     * may easily occur later in the variable list.
     *
     * So first, we rewind to the head of the list....
     */
    for (req=request; req->prev; req=req->prev)
        ;

    /*
     * ... and then start looking for matching indexes
     * (by constructing OIDs from these index values)
     */
    for (; req; req=req->next) {
        table_info = netsnmp_extract_table_info(req);
        that_index = table_info->indexes;
        build_oid_noalloc(that_oid, MAX_OID_LEN, &that_oid_len,
                          base_oid, 2, that_index);
      
        /*
         * This request has the same index values,
         * so add the newly-created row information.
         */
        if (snmp_oid_compare(this_oid, this_oid_len,
                             that_oid, that_oid_len) == 0) {
            netsnmp_request_add_list_data(req,
                netsnmp_create_data_list(TABLE_DATA_ROW, row, NULL));
        }
    }
}

/** extracts the row being accessed passed from the table_data helper */
netsnmp_table_row *
netsnmp_extract_table_row(netsnmp_request_info *request)
{
    return (netsnmp_table_row *) netsnmp_request_get_list_data(request,
                                                               TABLE_DATA_ROW);
}

/** extracts the table being accessed passed from the table_data helper */
netsnmp_table_data *
netsnmp_extract_table(netsnmp_request_info *request)
{
    return (netsnmp_table_data *) netsnmp_request_get_list_data(request,
                                                               TABLE_DATA_TABLE);
}

/** extracts the data from the row being accessed passed from the
 * table_data helper */
void           *
netsnmp_extract_table_row_data(netsnmp_request_info *request)
{
    netsnmp_table_row *row;
    row = (netsnmp_table_row *) netsnmp_extract_table_row(request);
    if (row)
        return row->data;
    else
        return NULL;
}

/** builds a result given a row, a varbind to set and the data */
int
netsnmp_table_data_build_result(netsnmp_handler_registration *reginfo,
                                netsnmp_agent_request_info *reqinfo,
                                netsnmp_request_info *request,
                                netsnmp_table_row *row,
                                int column,
                                u_char type,
                                u_char * result_data,
                                size_t result_data_len)
{
    oid             build_space[MAX_OID_LEN];

    if (!reginfo || !reqinfo || !request)
        return SNMPERR_GENERR;

    if (reqinfo->mode == MODE_GETNEXT || reqinfo->mode == MODE_GETBULK) {
        /*
         * only need to do this for getnext type cases where oid is changing 
         */
        memcpy(build_space, reginfo->rootoid,   /* registered oid */
               reginfo->rootoid_len * sizeof(oid));
        build_space[reginfo->rootoid_len] = 1;  /* entry */
        build_space[reginfo->rootoid_len + 1] = column; /* column */
        memcpy(build_space + reginfo->rootoid_len + 2,  /* index data */
               row->index_oid, row->index_oid_len * sizeof(oid));
        snmp_set_var_objid(request->requestvb, build_space,
                           reginfo->rootoid_len + 2 + row->index_oid_len);
    }
    snmp_set_var_typed_value(request->requestvb, type,
                             result_data, result_data_len);
    return SNMPERR_SUCCESS;     /* WWWXXX: check for bounds */
}

/** clones a data row. DOES NOT CLONE THE CONTAINED DATA. */
netsnmp_table_row *
netsnmp_table_data_clone_row(netsnmp_table_row *row)
{
    netsnmp_table_row *newrow = NULL;
    if (!row)
        return NULL;

    memdup((u_char **) & newrow, (u_char *) row,
           sizeof(netsnmp_table_row));
    if (!newrow)
        return NULL;

    if (row->indexes) {
        newrow->indexes = snmp_clone_varbind(newrow->indexes);
        if (!newrow->indexes)
            return NULL;
    }

    if (row->index_oid) {
        memdup((u_char **) & newrow->index_oid,
               (u_char *) row->index_oid,
               row->index_oid_len * sizeof(oid));
        if (!newrow->index_oid)
            return NULL;
    }

    return newrow;
}

int
netsnmp_table_data_num_rows(netsnmp_table_data *table)
{
    int i=0;
    netsnmp_table_row *row;
    if (!table)
        return 0;
    for (row = table->first_row; row; row = row->next) {
        i++;
    }
    return i;
}
/*
 * @} 
 */