blob: 7034d781868d1d76b67474ebc1a02bbb4f7068e2 [file] [log] [blame]
#include <net-snmp/net-snmp-config.h>
#include <sys/types.h>
#if HAVE_STRING_H
#include <string.h>
#endif
#include <net-snmp/net-snmp-includes.h>
#include <net-snmp/agent/net-snmp-agent-includes.h>
#include <net-snmp/agent/bulk_to_next.h>
/***********************************************************************/
/*
* New Handler based API
*/
/***********************************************************************/
/** @defgroup handler Agent handler API
* @ingroup agent
*
* The basic theory goes something like this: In the past, with the
* original mib module api (which derived from the original CMU SNMP
* code) the underlying mib modules were passed very little
* information (only the truly most basic information about a
* request). This worked well at the time but in todays world of
* subagents, device instrumentation, low resource consumption, etc,
* it just isn't flexible enough. "handlers" are here to fix all that.
*
* With the rewrite of the agent internals for the net-snmp 5.0
* release, we introduce a modular calling scheme that allows agent
* modules to be written in a very flexible manner, and more
* importantly allows reuse of code in a decent way (and without the
* memory and speed overheads of OO languages like C++).
*
* Functionally, the notion of what a handler does is the same as the
* older api: A handler is @link netsnmp_create_handler() created@endlink and
* then @link netsnmp_register_handler() registered@endlink with the main
* agent at a given OID in the OID tree and gets called any time a
* request is made that it should respond to. You probably should
* use one of the convenience helpers instead of doing anything else
* yourself though:
*
* Most importantly, though, is that the handlers are built on the
* notion of modularity and reuse. Specifically, rather than do all
* the really hard work (like parsing table indexes out of an
* incoming oid request) in each module, the API is designed to make
* it easy to write "helper" handlers that merely process some aspect
* of the request before passing it along to the final handler that
* returns the real answer. Most people will want to make use of the
* @link instance instance@endlink, @link table table@endlink, @link
* table_iterator table_iterator@endlink, @link table_data
* table_data@endlink, or @link table_dataset table_dataset@endlink
* helpers to make their life easier. These "helpers" interpert
* important aspects of the request and pass them on to you.
*
* For instance, the @link table table@endlink helper is designed to
* hand you a list of extracted index values from an incoming
* request. THe @link table_iterator table_iterator@endlink helper
* is built on top of the table helper, and is designed to help you
* iterate through data stored elsewhere (like in a kernel) that is
* not in OID lexographical order (ie, don't write your own index/oid
* sorting routine, use this helper instead). The beauty of the
* @link table_iterator table_iterator helper@, as well as the @link
* instance instance@ helper is that they take care of the complex
* GETNEXT processing entirely for you and hand you everything you
* need to merely return the data as if it was a GET request. Much
* less code and hair pulling. I've pulled all my hair out to help
* you so that only one of us has to be bald.
*
* @{
*/
/** creates a netsnmp_mib_handler structure given a name and a access method.
* The returned handler should then be @link netsnmp_register_handler()
* registered.@endlink
* @see netsnmp_create_handler_registration()
* @see netsnmp_register_handler()
*/
netsnmp_mib_handler *
netsnmp_create_handler(const char *name,
Netsnmp_Node_Handler * handler_access_method)
{
netsnmp_mib_handler *ret = SNMP_MALLOC_TYPEDEF(netsnmp_mib_handler);
ret->handler_name = strdup(name);
ret->access_method = handler_access_method;
return ret;
}
/** creates a handler registration structure given a name, a
* access_method function, a registration location oid and the modes
* the handler supports. If modes == 0, then modes will automatically
* be set to the default value of only HANDLER_CAN_DEFAULT, which is
* by default read-only GET and GETNEXT requests.
* @note This ends up calling netsnmp_create_handler(name, handler_access_method)
* @see netsnmp_create_handler()
* @see netsnmp_register_handler()
*/
netsnmp_handler_registration *
netsnmp_create_handler_registration(const char *name,
Netsnmp_Node_Handler *
handler_access_method, oid * reg_oid,
size_t reg_oid_len, int modes)
{
netsnmp_handler_registration *the_reg;
the_reg = SNMP_MALLOC_TYPEDEF(netsnmp_handler_registration);
if (!the_reg)
return NULL;
if (modes)
the_reg->modes = modes;
else
the_reg->modes = HANDLER_CAN_DEFAULT;
the_reg->handler = netsnmp_create_handler(name, handler_access_method);
if (name)
the_reg->handlerName = strdup(name);
memdup((u_char **) & the_reg->rootoid, (const u_char *) reg_oid,
reg_oid_len * sizeof(oid));
the_reg->rootoid_len = reg_oid_len;
return the_reg;
}
/** register a handler, as defined by the netsnmp_handler_registration pointer. */
int
netsnmp_register_handler(netsnmp_handler_registration *reginfo)
{
netsnmp_mib_handler *handler;
DEBUGIF("handler::register") {
DEBUGMSGTL(("handler::register", "Registering "));
for (handler = reginfo->handler; handler; handler = handler->next) {
DEBUGMSG(("handler::register", "::%s", handler->handler_name));
}
DEBUGMSG(("handler::register", " at "));
if (reginfo->rootoid && reginfo->range_subid) {
DEBUGMSGOIDRANGE(("handler::register", reginfo->rootoid,
reginfo->rootoid_len, reginfo->range_subid,
reginfo->range_ubound));
} else if (reginfo->rootoid) {
DEBUGMSGOID(("handler::register", reginfo->rootoid,
reginfo->rootoid_len));
} else {
DEBUGMSG(("handler::register", "[null]"));
}
DEBUGMSG(("handler::register", "\n"));
}
/*
* don't let them register for absolutely nothing. Probably a mistake
*/
if (0 == reginfo->modes) {
reginfo->modes = HANDLER_CAN_DEFAULT;
}
/*
* for handlers that can't GETBULK, force a conversion handler on them
*/
if (!(reginfo->modes & HANDLER_CAN_GETBULK)) {
netsnmp_inject_handler(reginfo,
netsnmp_get_bulk_to_next_handler());
}
return netsnmp_register_mib(reginfo->handler->handler_name,
NULL, 0, 0,
reginfo->rootoid, reginfo->rootoid_len,
reginfo->priority,
reginfo->range_subid,
reginfo->range_ubound, NULL,
reginfo->contextName, reginfo->timeout, 0,
reginfo, 1);
}
/** register a handler, as defined by the netsnmp_handler_registration pointer. */
int
netsnmp_register_handler_nocallback(netsnmp_handler_registration *reginfo)
{
netsnmp_mib_handler *handler;
DEBUGIF("handler::register") {
DEBUGMSGTL(("handler::register",
"Registering (with no callback) "));
for (handler = reginfo->handler; handler; handler = handler->next) {
DEBUGMSG(("handler::register", "::%s", handler->handler_name));
}
DEBUGMSG(("handler::register", " at "));
if (reginfo->rootoid && reginfo->range_subid) {
DEBUGMSGOIDRANGE(("handler::register", reginfo->rootoid,
reginfo->rootoid_len, reginfo->range_subid,
reginfo->range_ubound));
} else if (reginfo->rootoid) {
DEBUGMSGOID(("handler::register", reginfo->rootoid,
reginfo->rootoid_len));
} else {
DEBUGMSG(("handler::register", "[null]"));
}
DEBUGMSG(("handler::register", "\n"));
}
/*
* don't let them register for absolutely nothing. Probably a mistake
*/
if (0 == reginfo->modes) {
reginfo->modes = HANDLER_CAN_DEFAULT;
}
return netsnmp_register_mib(reginfo->handler->handler_name,
NULL, 0, 0,
reginfo->rootoid, reginfo->rootoid_len,
reginfo->priority,
reginfo->range_subid,
reginfo->range_ubound, NULL,
reginfo->contextName, reginfo->timeout, 0,
reginfo, 0);
}
/** inject a new handler into the calling chain of the handlers
definedy by the netsnmp_handler_registration pointer. The new handler is
injected at the top of the list and hence will be the new handler
to be called first.*/
int
netsnmp_inject_handler(netsnmp_handler_registration *reginfo,
netsnmp_mib_handler *handler)
{
DEBUGMSGTL(("handler:inject", "injecting %s before %s\n",
handler->handler_name, reginfo->handler->handler_name));
handler->next = reginfo->handler;
if (reginfo->handler)
reginfo->handler->prev = handler;
reginfo->handler = handler;
return SNMPERR_SUCCESS;
}
/** @internal
* calls all the handlers for a given mode.
*/
int
netsnmp_call_handlers(netsnmp_handler_registration *reginfo,
netsnmp_agent_request_info *reqinfo,
netsnmp_request_info *requests)
{
Netsnmp_Node_Handler *nh;
int status;
if (reginfo == NULL || reqinfo == NULL || requests == NULL) {
snmp_log(LOG_ERR, "netsnmp_call_handlers() called illegally\n");
return SNMP_ERR_GENERR;
}
if (reginfo->handler == NULL) {
snmp_log(LOG_ERR, "no handler specified.");
return SNMP_ERR_GENERR;
}
switch (reqinfo->mode) {
case MODE_GETBULK:
case MODE_GET:
case MODE_GETNEXT:
if (!(reginfo->modes & HANDLER_CAN_GETANDGETNEXT))
return SNMP_ERR_NOERROR; /* legal */
break;
case MODE_SET_RESERVE1:
case MODE_SET_RESERVE2:
case MODE_SET_ACTION:
case MODE_SET_COMMIT:
case MODE_SET_FREE:
case MODE_SET_UNDO:
if (!(reginfo->modes & HANDLER_CAN_SET)) {
for (; requests; requests = requests->next) {
netsnmp_set_request_error(reqinfo, requests,
SNMP_ERR_NOTWRITABLE);
}
return SNMP_ERR_NOERROR;
}
break;
default:
snmp_log(LOG_ERR, "unknown mode in netsnmp_call_handlers! bug!\n");
return SNMP_ERR_GENERR;
}
DEBUGMSGTL(("handler:calling", "calling main handler %s\n",
reginfo->handler->handler_name));
nh = reginfo->handler->access_method;
if (!nh) {
snmp_log(LOG_ERR, "no handler access method specified.");
return SNMP_ERR_GENERR;
}
/*
* XXX: define acceptable return statuses
*/
status = (*nh) (reginfo->handler, reginfo, reqinfo, requests);
return status;
}
/** calls a handler with with appropriate NULL checking of arguments, etc. */
inline int
netsnmp_call_handler(netsnmp_mib_handler *next_handler,
netsnmp_handler_registration *reginfo,
netsnmp_agent_request_info *reqinfo,
netsnmp_request_info *requests)
{
Netsnmp_Node_Handler *nh;
int ret;
if (next_handler == NULL || reginfo == NULL || reqinfo == NULL ||
requests == NULL) {
snmp_log(LOG_ERR, "netsnmp_call_handler() called illegally\n");
return SNMP_ERR_GENERR;
}
nh = next_handler->access_method;
if (!nh) {
snmp_log(LOG_ERR, "no access method specified in handler %s.",
next_handler->handler_name);
return SNMP_ERR_GENERR;
}
DEBUGMSGTL(("handler:calling", "calling handler %s\n",
next_handler->handler_name));
ret = (*nh) (next_handler, reginfo, reqinfo, requests);
DEBUGMSGTL(("handler:returned", "handler %s returned %d\n",
next_handler->handler_name, ret));
return ret;
}
/** calls the next handler in the chain after the current one with
with appropriate NULL checking, etc. */
inline int
netsnmp_call_next_handler(netsnmp_mib_handler *current,
netsnmp_handler_registration *reginfo,
netsnmp_agent_request_info *reqinfo,
netsnmp_request_info *requests)
{
if (current == NULL || reginfo == NULL || reqinfo == NULL ||
requests == NULL) {
snmp_log(LOG_ERR, "netsnmp_call_next_handler() called illegally\n");
return SNMP_ERR_GENERR;
}
return netsnmp_call_handler(current->next, reginfo, reqinfo, requests);
}
/** calls the next handler in the chain after the current one with
with appropriate NULL checking, etc. */
inline int
netsnmp_call_next_handler_one_request(netsnmp_mib_handler *current,
netsnmp_handler_registration *reginfo,
netsnmp_agent_request_info *reqinfo,
netsnmp_request_info *requests)
{
netsnmp_request_info *request;
int ret;
if (!requests)
return NULL;
request = requests->next;
requests->next = NULL;
ret = netsnmp_call_handler(current->next, reginfo, reqinfo, requests);
requests->next = request;
return ret;
}
/** free's the resourceses associated with a given handler */
void
netsnmp_handler_free(netsnmp_mib_handler *handler)
{
if (handler != NULL) {
if (handler->next != NULL) {
netsnmp_handler_free(handler->next);
handler->next = NULL;
}
SNMP_FREE(handler->handler_name);
free(handler);
}
}
/** dulpicates a handler */
netsnmp_mib_handler *
netsnmp_handler_dup(netsnmp_mib_handler *handler)
{
netsnmp_mib_handler *h = NULL;
if (handler == NULL) {
return NULL;
}
h = (netsnmp_mib_handler *) calloc(1, sizeof(netsnmp_mib_handler));
if (h != NULL) {
h->myvoid = handler->myvoid;
h->access_method = handler->access_method;
if (handler->handler_name != NULL) {
h->handler_name = strdup(handler->handler_name);
if (h->handler_name == NULL) {
free(h);
return NULL;
}
}
if (handler->next != NULL) {
h->next = netsnmp_handler_dup(handler->next);
if (h->next == NULL) {
if (h->handler_name) {
free(h->handler_name);
}
free(h);
return NULL;
}
h->next->prev = h;
}
h->prev = NULL;
return h;
}
return NULL;
}
/** free the resources associated with a handler registration object */
void
netsnmp_handler_registration_free(netsnmp_handler_registration *reginfo)
{
if (reginfo != NULL) {
netsnmp_handler_free(reginfo->handler);
SNMP_FREE(reginfo->handlerName);
SNMP_FREE(reginfo->contextName);
SNMP_FREE(reginfo->rootoid);
free(reginfo);
}
}
/** duplicates the handler registration object */
netsnmp_handler_registration *
netsnmp_handler_registration_dup(netsnmp_handler_registration *reginfo)
{
netsnmp_handler_registration *r = NULL;
if (reginfo == NULL) {
return NULL;
}
r = (netsnmp_handler_registration *) calloc(1,
sizeof
(netsnmp_handler_registration));
if (r != NULL) {
r->modes = reginfo->modes;
r->priority = reginfo->priority;
r->range_subid = reginfo->range_subid;
r->timeout = reginfo->timeout;
r->range_ubound = reginfo->range_ubound;
r->rootoid_len = reginfo->rootoid_len;
if (reginfo->handlerName != NULL) {
r->handlerName = strdup(reginfo->handlerName);
if (r->handlerName == NULL) {
netsnmp_handler_registration_free(r);
return NULL;
}
}
if (reginfo->contextName != NULL) {
r->contextName = strdup(reginfo->contextName);
if (r->contextName == NULL) {
netsnmp_handler_registration_free(r);
return NULL;
}
}
if (reginfo->rootoid != NULL) {
memdup((u_char **) & (r->rootoid),
(const u_char *) reginfo->rootoid,
reginfo->rootoid_len * sizeof(oid));
if (r->rootoid == NULL) {
netsnmp_handler_registration_free(r);
return NULL;
}
}
r->handler = netsnmp_handler_dup(reginfo->handler);
if (r->handler == NULL) {
netsnmp_handler_registration_free(r);
return NULL;
}
return r;
}
return NULL;
}
/** creates a cache of information which can be saved for future
reference. Use netsnmp_handler_check_cache() later to make sure it's still
valid before referencing it in the future. */
inline netsnmp_delegated_cache *
netsnmp_create_delegated_cache(netsnmp_mib_handler *handler,
netsnmp_handler_registration *reginfo,
netsnmp_agent_request_info *reqinfo,
netsnmp_request_info *requests,
void *localinfo)
{
netsnmp_delegated_cache *ret;
ret = SNMP_MALLOC_TYPEDEF(netsnmp_delegated_cache);
if (ret) {
ret->transaction_id = reqinfo->asp->pdu->transid;
ret->handler = handler;
ret->reginfo = reginfo;
ret->reqinfo = reqinfo;
ret->requests = requests;
ret->localinfo = localinfo;
}
return ret;
}
/** check's a given cache and returns it if it is still valid (ie, the
agent still considers it to be an outstanding request. Returns
NULL if it's no longer valid. */
inline netsnmp_delegated_cache *
netsnmp_handler_check_cache(netsnmp_delegated_cache *dcache)
{
if (!dcache)
return dcache;
if (netsnmp_check_transaction_id(dcache->transaction_id) ==
SNMPERR_SUCCESS)
return dcache;
return NULL;
}
/** frees a cache once you're finished using it */
inline void
netsnmp_free_delegated_cache(netsnmp_delegated_cache *dcache)
{
/*
* right now, no extra data is there that needs to be freed
*/
if (dcache)
free(dcache);
return;
}
/** marks a list of requests as delegated (or not if isdelegaded = 0) */
void
netsnmp_handler_mark_requests_as_delegated(netsnmp_request_info *requests,
int isdelegated)
{
while (requests) {
requests->delegated = isdelegated;
requests = requests->next;
}
}
/** add data to a request that can be extracted later by submodules */
inline void
netsnmp_request_add_list_data(netsnmp_request_info *request,
netsnmp_data_list *node)
{
if (request) {
if (request->parent_data)
netsnmp_add_list_data(&request->parent_data, node);
else
request->parent_data = node;
}
}
/** extract data from a request that was added previously by a parent module */
inline void *
netsnmp_request_get_list_data(netsnmp_request_info *request,
const char *name)
{
if (request)
return netsnmp_get_list_data(request->parent_data, name);
return NULL;
}
/** Free the extra data stored in a request */
inline void
netsnmp_free_request_data_set(netsnmp_request_info *request)
{
if (request)
netsnmp_free_list_data(request->parent_data);
}
/** Free the extra data stored in a bunch of requests (all data in the chain) */
inline void
netsnmp_free_request_data_sets(netsnmp_request_info *request)
{
if (request && request->parent_data) {
netsnmp_free_all_list_data(request->parent_data);
request->parent_data = NULL;
}
}
/** Returns a handler from a chain based on the name */
netsnmp_mib_handler *
netsnmp_find_handler_by_name(netsnmp_handler_registration *reginfo,
const char *name)
{
netsnmp_mib_handler *it;
for (it = reginfo->handler; it; it = it->next) {
if (strcmp(it->handler_name, name) == 0) {
return it;
}
}
return NULL;
}
/** Returns a handler's void * pointer from a chain based on the name.
This probably shouldn't be used by the general public as the void *
data may change as a handler evolves. Handlers should really
advertise some function for you to use instead. */
void *
netsnmp_find_handler_data_by_name(netsnmp_handler_registration *reginfo,
const char *name)
{
netsnmp_mib_handler *it = netsnmp_find_handler_by_name(reginfo, name);
if (it)
return it->myvoid;
return NULL;
}
/** clones a mib handler (it's name and access methods onlys; not myvoid)
*/
netsnmp_mib_handler *
clone_handler(netsnmp_mib_handler *it)
{
return netsnmp_create_handler(it->handler_name, it->access_method);
}
static netsnmp_data_list *handler_reg = NULL;
/** registers a given handler by name so that it can be found easily later.
*/
void
netsnmp_register_handler_by_name(const char *name,
netsnmp_mib_handler *handler)
{
netsnmp_add_list_data(&handler_reg,
netsnmp_create_data_list(name, (void *) handler,
NULL));
DEBUGMSGTL(("handler_registry", "registering helper %s\n", name));
}
/** @internal
* injects a handler into a subtree, peers and children when a given
* subtrees name matches a passed in name.
*/
void
netsnmp_inject_handler_into_subtree(netsnmp_subtree *tp, const char *name,
netsnmp_mib_handler *handler)
{
netsnmp_subtree *tptr;
netsnmp_mib_handler *mh;
for (tptr = tp; tptr != NULL; tptr = tptr->next) {
/* if (tptr->children) {
netsnmp_inject_handler_into_subtree(tptr->children,name,handler);
} */
if (strcmp(tptr->label_a, name) == 0) {
DEBUGMSGTL(("injectHandler", "injecting handler %s into %s\n",
handler->handler_name, tptr->label_a));
netsnmp_inject_handler(tptr->reginfo, clone_handler(handler));
} else if (tptr->reginfo != NULL &&
tptr->reginfo->handlerName != NULL &&
strcmp(tptr->reginfo->handlerName, name) == 0) {
DEBUGMSGTL(("injectHandler", "injecting handler into %s/%s\n",
tptr->label_a, tptr->reginfo->handlerName));
netsnmp_inject_handler(tptr->reginfo, clone_handler(handler));
} else {
for (mh = tptr->reginfo->handler; mh != NULL; mh = mh->next) {
if (mh->handler_name && strcmp(mh->handler_name, name) == 0) {
DEBUGMSGTL(("injectHandler", "injecting handler into %s\n",
tptr->label_a));
netsnmp_inject_handler(tptr->reginfo,
clone_handler(handler));
break;
} else {
DEBUGMSGTL(("yyyinjectHandler",
"not injecting handler into %s\n",
mh->handler_name));
}
}
}
}
}
static int doneit = 0;
/** @internal
* parses the "injectHandler" token line.
*/
void
parse_injectHandler_conf(const char *token, char *cptr)
{
char handler_to_insert[256];
subtree_context_cache *stc;
netsnmp_mib_handler *handler;
/*
* XXXWWW: ensure instead that handler isn't inserted twice
*/
if (doneit) /* we only do this once without restart the agent */
return;
cptr = copy_nword(cptr, handler_to_insert, sizeof(handler_to_insert));
handler = netsnmp_get_list_data(handler_reg, handler_to_insert);
if (!handler) {
config_perror("no such \"%s\" handler registered.");
return;
}
if (!cptr) {
config_perror("no INTONAME specified. Can't do insertion.");
return;
}
for (stc = get_top_context_cache(); stc; stc = stc->next) {
DEBUGMSGTL(("injectHandler", "Checking context tree %s\n",
stc->context_name));
netsnmp_inject_handler_into_subtree(stc->first_subtree, cptr,
handler);
}
}
/** @internal
* callback to ensure injectHandler parser doesn't do things twice
* @todo replace this with a method to check the handler chain instead.
*/
static int
handler_mark_doneit(int majorID, int minorID,
void *serverarg, void *clientarg)
{
doneit = 1;
return 0;
}
/** @internal
* register's the injectHandle parser token.
*/
void
netsnmp_init_handler_conf(void)
{
snmpd_register_config_handler("injectHandler",
parse_injectHandler_conf,
NULL, "injectHandler NAME INTONAME");
snmp_register_callback(SNMP_CALLBACK_LIBRARY,
SNMP_CALLBACK_POST_READ_CONFIG,
handler_mark_doneit, NULL);
se_add_pair_to_slist("agent_mode", strdup("GET"), MODE_GET);
se_add_pair_to_slist("agent_mode", strdup("GETNEXT"), MODE_GETNEXT);
se_add_pair_to_slist("agent_mode", strdup("GETBULK"), MODE_GETBULK);
se_add_pair_to_slist("agent_mode", strdup("SET_BEGIN"),
MODE_SET_BEGIN);
se_add_pair_to_slist("agent_mode", strdup("SET_RESERVE1"),
MODE_SET_RESERVE1);
se_add_pair_to_slist("agent_mode", strdup("SET_RESERVE2"),
MODE_SET_RESERVE2);
se_add_pair_to_slist("agent_mode", strdup("SET_ACTION"),
MODE_SET_ACTION);
se_add_pair_to_slist("agent_mode", strdup("SET_COMMIT"),
MODE_SET_COMMIT);
se_add_pair_to_slist("agent_mode", strdup("SET_FREE"), MODE_SET_FREE);
se_add_pair_to_slist("agent_mode", strdup("SET_UNDO"), MODE_SET_UNDO);
se_add_pair_to_slist("handler_can_mode", strdup("GET/GETNEXT"),
HANDLER_CAN_GETANDGETNEXT);
se_add_pair_to_slist("handler_can_mode", strdup("SET"),
HANDLER_CAN_SET);
se_add_pair_to_slist("handler_can_mode", strdup("GETBULK"),
HANDLER_CAN_GETBULK);
}
/** @} */