/*

 * netsnmp_data_list.c

 *

 * Portions of this file are subject to the following copyright(s).  See

 * the Net-SNMP's COPYING file for more details and other copyrights

 * that may apply:

 *

 * Portions of this file are copyrighted by:

 * Copyright (c) 2016 VMware, Inc. All rights reserved.

 * Use is subject to license terms specified in the COPYING file

 * distributed with the Net-SNMP package.

 */

#include <net-snmp/net-snmp-config.h>

#include <net-snmp/net-snmp-features.h>

#include <net-snmp/net-snmp-includes.h>

netsnmp_feature_child_of(data_list_all, libnetsnmp)

netsnmp_feature_child_of(data_list_add_data, data_list_all)

netsnmp_feature_child_of(data_list_get_list_node, data_list_all)

/** @defgroup data_list generic linked-list data handling with a string as a key.

 * @ingroup library

 * @{

*/

/** frees the data and a name at a given data_list node.

 * Note that this doesn't free the node itself.

 * @param node the node for which the data should be freed

 */

NETSNMP_INLINE void

netsnmp_free_list_data(netsnmp_data_list *node)

{

    Netsnmp_Free_List_Data *beer;

    if (!node)

        return;

    beer = node->free_func;

    if (beer)

        (beer) (node->data);

    SNMP_FREE(node->name);

}

/** frees all data and nodes in a list.

 * @param head the top node of the list to be freed.

 */

NETSNMP_INLINE void

netsnmp_free_all_list_data(netsnmp_data_list *head)

{

    netsnmp_data_list *tmpptr;

    for (; head;) {

        netsnmp_free_list_data(head);

        tmpptr = head;

        head = head->next;

        SNMP_FREE(tmpptr);

    }

}

/** adds creates a data_list node given a name, data and a free function ptr.

 * @param name the name of the node to cache the data.

 * @param data the data to be stored under that name

 * @param beer A function that can free the data pointer (in the future)

 * @return a newly created data_list node which can be given to the netsnmp_add_list_data function.

 */

NETSNMP_INLINE netsnmp_data_list *

netsnmp_create_data_list(const char *name, void *data,

                         Netsnmp_Free_List_Data * beer)

{

    netsnmp_data_list *node;

    if (!name)

        return NULL;

    node = SNMP_MALLOC_TYPEDEF(netsnmp_data_list);

    if (!node)

        return NULL;

    node->name = strdup(name);

    if (!node->name) {

        free(node);

        return NULL;

    }

    node->data = data;

    node->free_func = beer;

    return node;

}

/** adds data to a datalist

 * @param head a pointer to the head node of a data_list

 * @param node a node to stash in the data_list

 */

NETSNMP_INLINE void

netsnmp_data_list_add_node(netsnmp_data_list **head, netsnmp_data_list *node)

{

    netsnmp_data_list *ptr;

    netsnmp_assert(NULL != head);

    netsnmp_assert(NULL != node);

    if (!head || !node)

        return;

    netsnmp_assert(NULL != node->name);

    DEBUGMSGTL(("data_list","adding key '%s'\n", node->name));

    if (!*head) {

        *head = node;

        return;

    }

    if (0 == strcmp(node->name, (*head)->name)) {

        netsnmp_assert(!"list key == is unique"); /* always fail */

        snmp_log(LOG_WARNING,

                 "WARNING: adding duplicate key '%s' to data list\n",

                 node->name);

    }

    for (ptr = *head; ptr->next != NULL; ptr = ptr->next) {

        netsnmp_assert(NULL != ptr->name);

        if (0 == strcmp(node->name, ptr->name)) {

            netsnmp_assert(!"list key == is unique"); /* always fail */

            snmp_log(LOG_WARNING,

                     "WARNING: adding duplicate key '%s' to data list\n",

                     node->name);

        }

    }

    netsnmp_assert(NULL != ptr);

    if (ptr)                    /* should always be true */

        ptr->next = node;

}

/** adds data to a datalist

 * @note netsnmp_data_list_add_node is preferred

 * @param head a pointer to the head node of a data_list

 * @param node a node to stash in the data_list

 */

/**  */

NETSNMP_INLINE void

netsnmp_add_list_data(netsnmp_data_list **head, netsnmp_data_list *node)

{

    netsnmp_data_list_add_node(head, node);

}

/** adds data to a datalist

 * @param head a pointer to the head node of a data_list

 * @param name the name of the node to cache the data.

 * @param data the data to be stored under that name

 * @param beer A function that can free the data pointer (in the future)

 * @return a newly created data_list node which was inserted in the list

 */

#ifndef NETSNMP_FEATURE_REMOVE_DATA_LIST_ADD_DATA

NETSNMP_INLINE netsnmp_data_list *

netsnmp_data_list_add_data(netsnmp_data_list **head, const char *name,

                           void *data, Netsnmp_Free_List_Data * beer)

{

    netsnmp_data_list *node;

    if (!name) {

        snmp_log(LOG_ERR,"no name provided.");

        return NULL;

    }

    node = netsnmp_create_data_list(name, data, beer);

    if(NULL == node) {

        snmp_log(LOG_ERR,"could not allocate memory for node.");

        return NULL;

    }

    netsnmp_add_list_data(head, node);

    return node;

}

#endif /* NETSNMP_FEATURE_REMOVE_DATA_LIST_ADD_DATA */

/** returns a data_list node's data for a given name within a data_list

 * @param head the head node of a data_list

 * @param name the name to find

 * @return a pointer to the data cached at that node

 */

NETSNMP_INLINE void    *

netsnmp_get_list_data(netsnmp_data_list *head, const char *name)

{

    if (!name)

        return NULL;

    for (; head; head = head->next)

        if (head->name && strcmp(head->name, name) == 0)

            break;

    if (head)

        return head->data;

    return NULL;

}

/** returns a data_list node for a given name within a data_list

 * @param head the head node of a data_list

 * @param name the name to find

 * @return a pointer to the data_list node

 */

#ifndef NETSNMP_FEATURE_REMOVE_DATA_LIST_GET_LIST_NODE

NETSNMP_INLINE netsnmp_data_list    *

netsnmp_get_list_node(netsnmp_data_list *head, const char *name)

{

    if (!name)

        return NULL;

    for (; head; head = head->next)

        if (head->name && strcmp(head->name, name) == 0)

            break;

    if (head)

        return head;

    return NULL;

}

#endif /* NETSNMP_FEATURE_REMOVE_DATA_LIST_GET_LIST_NODE */

/** Removes a named node from a data_list (and frees it)

 * @param realhead a pointer to the head node of a data_list

 * @param name the name to find and remove

 * @return 0 on successful find-and-delete, 1 otherwise.

 */

int

netsnmp_remove_list_node(netsnmp_data_list **realhead, const char *name)

{

    netsnmp_data_list *head, *prev;

    if (!name)

        return 1;

    for (head = *realhead, prev = NULL; head;

         prev = head, head = head->next) {

        if (head->name && strcmp(head->name, name) == 0) {

            if (prev)

                prev->next = head->next;

            else

                *realhead = head->next;

            netsnmp_free_list_data(head);

            free(head);

            return 0;

        }

    }

    return 1;

}

/** used to store registered save/parse handlers (specifically, parsing info) */

static netsnmp_data_list *saveHead;

/** registers to store a data_list set of data at persistent storage time

 *

 * @param datalist the data to be saved

 * @param type the name of the application to save the data as.  If left NULL the default application name that was registered during the init_snmp call will be used (recommended).

 * @param token the unique token identifier string to use as the first word in the persistent file line.

 * @param data_list_save_ptr a function pointer which will be called to save the rest of the data to a buffer.

 * @param data_list_read_ptr a function pointer which can read the remainder of a saved line and return the application specific void * pointer.

 * @param data_list_free_ptr a function pointer which will be passed to the data node for freeing it in the future when/if the list/node is cleaned up or destroyed.

 */

void

netsnmp_register_save_list(netsnmp_data_list **datalist,

                           const char *type, const char *token,

                           Netsnmp_Save_List_Data *data_list_save_ptr,

                           Netsnmp_Read_List_Data *data_list_read_ptr,

                           Netsnmp_Free_List_Data *data_list_free_ptr)

{

    netsnmp_data_list_saveinfo *info;

    if (!data_list_save_ptr && !data_list_read_ptr)

        return;

    info = SNMP_MALLOC_TYPEDEF(netsnmp_data_list_saveinfo);

    if (!info) {

        snmp_log(LOG_ERR, "couldn't malloc a netsnmp_data_list_saveinfo typedef");

        return;

    }

    info->datalist = datalist;

    info->token = token;

    info->type = type;

    if (!info->type) {

        info->type = netsnmp_ds_get_string(NETSNMP_DS_LIBRARY_ID,

                                           NETSNMP_DS_LIB_APPTYPE);

    }

    /* function which will save the data */

    info->data_list_save_ptr = data_list_save_ptr;

    if (data_list_save_ptr)

        snmp_register_callback(SNMP_CALLBACK_LIBRARY, SNMP_CALLBACK_STORE_DATA,

                               netsnmp_save_all_data_callback, info);

    /* function which will read the data back in */

    info->data_list_read_ptr = data_list_read_ptr;

    if (data_list_read_ptr) {

        /** @todo netsnmp_register_save_list should handle the same token name being saved from different types? */

        netsnmp_add_list_data(&saveHead,

                              netsnmp_create_data_list(token, info, NULL));

        register_config_handler(type, token, netsnmp_read_data_callback,

                                NULL /* XXX */, NULL);

    }

    info->data_list_free_ptr = data_list_free_ptr;

}

/** intended to be registerd as a callback operation.

 * It should be registered using:

 *

 * snmp_register_callback(SNMP_CALLBACK_LIBRARY, SNMP_CALLBACK_STORE_DATA, netsnmp_save_all_data_callback, INFO_POINTER);

 *

 * where INFO_POINTER is a pointer to a netsnmp_data_list_saveinfo object containing apporpriate registration information

 */

int

netsnmp_save_all_data_callback(int major, int minor,

                               void *serverarg, void *clientarg) {

    netsnmp_data_list_saveinfo *info = (netsnmp_data_list_saveinfo *)clientarg;

    if (!clientarg) {

        snmp_log(LOG_WARNING, "netsnmp_save_all_data_callback called with no passed data");

        return SNMP_ERR_NOERROR;

    }

    netsnmp_save_all_data(*(info->datalist), info->type, info->token,

                          info->data_list_save_ptr);

    return SNMP_ERR_NOERROR;

}    

/** intended to be called as a callback during persistent save operations.

 * See the netsnmp_save_all_data_callback for where this is typically used. */

int

netsnmp_save_all_data(netsnmp_data_list *head,

                      const char *type, const char *token,

                      Netsnmp_Save_List_Data * data_list_save_ptr)

{

    char buf[SNMP_MAXBUF], *cp;

    for (; head; head = head->next) {

        if (head->name) {

            /* save begining of line */

            snprintf(buf, sizeof(buf), "%s ", token);

            cp = buf + strlen(buf);

            cp = read_config_save_octet_string(cp, (u_char*)head->name,

                                               strlen(head->name));

            *cp++ = ' ';

            /* call registered function to save the rest */

            if (!(data_list_save_ptr)(cp,

                                      sizeof(buf) - strlen(buf),

                                      head->data)) {

                read_config_store(type, buf);

            }

        }

    }

    return SNMP_ERR_NOERROR;

}

/** intended to be registerd as a .conf parser

 * It should be registered using:

 *

 * register_app_config_handler("token", netsnmp_read_data_callback, XXX)

 *

 * where INFO_POINTER is a pointer to a netsnmp_data_list_saveinfo object

 * containing apporpriate registration information

 * @todo make netsnmp_read_data_callback deal with a free routine

 */

void

netsnmp_read_data_callback(const char *token, char *line) {

    netsnmp_data_list_saveinfo *info;

    char *dataname = NULL;

    size_t dataname_len;

    void *data = NULL;

    /* find the stashed information about what we're parsing */

    info = (netsnmp_data_list_saveinfo *) netsnmp_get_list_data(saveHead, token);

    if (!info) {

        snmp_log(LOG_WARNING, "netsnmp_read_data_callback called without previously registered subparser");

        return;

    }

    /* read in the token */

    line =

        read_config_read_data(ASN_OCTET_STR, line,

                              &dataname, &dataname_len);

    if (!line || !dataname)

        return;

    /* call the sub-parser to read the rest */

    data = (info->data_list_read_ptr)(line, strlen(line));

    if (!data) {

        free(dataname);

        return;

    }

    /* add to the datalist */

    netsnmp_add_list_data(info->datalist,

                          netsnmp_create_data_list(dataname, data,

                                                   info->data_list_free_ptr));

    return;

}

void

shutdown_data_list(void)

{

    netsnmp_free_all_list_data(saveHead);

}

/**  @} */