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Net-SNMP Agent handler and extensibility API
[The Net-SNMP 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). More...

Modules
group   utility_handlers: simplify request processing
  A group of handlers intended to simplify certain aspects of processing a request for a MIB object.
group   leaf_handlers: process individual leaf objects
  A group of handlers to implement individual leaf objects and instances (both scalar objects, and individual objects and instances within a table).
group   baby_steps: calls your handler in baby_steps for set processing.
group   old_api: Calls mib module code written in the old style of code.
  This is a backwards compatilibity module that allows code written in the old API to be run under the new handler based architecture.
group   stash_cache: automatically caches data for certain handlers.
  This handler caches data in an optimized way which may aleviate the need for the lower level handlers to perform as much optimization.
group   table: Helps you implement a table.
  This handler helps you implement a table by doing some of the processing for you.

Data Structures
struct   netsnmp_mib_handler_s
  the mib handler structure to be registered More...
struct   netsnmp_handler_registration_s
  Root registration info. More...
struct   netsnmp_handler_args_s
struct   netsnmp_delegated_cache_s
struct   netsnmp_mib_handler_s
  the mib handler structure to be registered More...
struct   netsnmp_handler_registration_s
  Root registration info. More...

Defines
#define  MIB_HANDLER_AUTO_NEXT   0x00000001
#define  MIB_HANDLER_AUTO_NEXT_OVERRIDE_ONCE   0x00000002
#define  MIB_HANDLER_CUSTOM4   0x10000000
#define  MIB_HANDLER_CUSTOM3   0x20000000
#define  MIB_HANDLER_CUSTOM2   0x40000000
#define  MIB_HANDLER_CUSTOM1   0x80000000
#define  HANDLER_CAN_GETANDGETNEXT   0x01
#define  HANDLER_CAN_SET   0x02
#define  HANDLER_CAN_GETBULK   0x04
#define  HANDLER_CAN_NOT_CREATE   0x08
#define  HANDLER_CAN_BABY_STEP   0x10
#define  HANDLER_CAN_STASH   0x20
#define  HANDLER_CAN_RONLY   (HANDLER_CAN_GETANDGETNEXT)
#define  HANDLER_CAN_RWRITE   (HANDLER_CAN_GETANDGETNEXT | HANDLER_CAN_SET)
#define  HANDLER_CAN_SET_ONLY   (HANDLER_CAN_SET | HANDLER_CAN_NOT_CREATE)
#define  HANDLER_CAN_DEFAULT   (HANDLER_CAN_RONLY | HANDLER_CAN_NOT_CREATE)
#define  REQUEST_IS_DELEGATED   1
#define  REQUEST_IS_NOT_DELEGATED   0

Typedefs
typedef netsnmp_mib_handler_s  netsnmp_mib_handler
  Typedefs the netsnmp_mib_handler_s struct into netsnmp_mib_handler.
typedef netsnmp_handler_registration_s  netsnmp_handler_registration
  Typedefs the netsnmp_handler_registration_s struct into netsnmp_handler_registration.
typedef int(  Netsnmp_Node_Handler )(netsnmp_mib_handler *handler, netsnmp_handler_registration *reginfo, netsnmp_agent_request_info *reqinfo, netsnmp_request_info *requests)
typedef netsnmp_handler_args_s  netsnmp_handler_args
typedef netsnmp_delegated_cache_s  netsnmp_delegated_cache

Functions
netsnmp_mib_handler *  netsnmp_create_handler (const char *name, Netsnmp_Node_Handler *handler_access_method)
  creates a netsnmp_mib_handler structure given a name and a access method.
netsnmp_handler_registration *  netsnmp_handler_registration_create (const char *name, netsnmp_mib_handler *handler, oid *reg_oid, size_t reg_oid_len, int modes)
  creates a handler registration structure given a name, a access_method function, a registration location oid and the modes the handler supports.
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)
int  netsnmp_register_handler (netsnmp_handler_registration *reginfo)
  register a handler, as defined by the netsnmp_handler_registration pointer.
int  netsnmp_unregister_handler (netsnmp_handler_registration *reginfo)
  unregister a handler, as defined by the netsnmp_handler_registration pointer.
int  netsnmp_register_handler_nocallback (netsnmp_handler_registration *reginfo)
  register a handler, as defined by the netsnmp_handler_registration pointer.
int  netsnmp_inject_handler_before (netsnmp_handler_registration *reginfo, netsnmp_mib_handler *handler, const char *before_what)
  inject a new handler into the calling chain of the handlers definedy by the netsnmp_handler_registration pointer.
int  netsnmp_inject_handler (netsnmp_handler_registration *reginfo, netsnmp_mib_handler *handler)
  inject a new handler into the calling chain of the handlers definedy by the netsnmp_handler_registration pointer.
NETSNMP_INLINE int  netsnmp_call_handler (netsnmp_mib_handler *next_handler, netsnmp_handler_registration *reginfo, netsnmp_agent_request_info *reqinfo, netsnmp_request_info *requests)
  calls a handler with with appropriate NULL checking of arguments, etc.
int  netsnmp_call_handlers (netsnmp_handler_registration *reginfo, netsnmp_agent_request_info *reqinfo, netsnmp_request_info *requests)
NETSNMP_INLINE int  netsnmp_call_next_handler (netsnmp_mib_handler *current, netsnmp_handler_registration *reginfo, netsnmp_agent_request_info *reqinfo, netsnmp_request_info *requests)
  calls the next handler in the chain after the current one with with appropriate NULL checking, etc.
NETSNMP_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)
  calls the next handler in the chain after the current one with with appropriate NULL checking, etc.
void  netsnmp_handler_free (netsnmp_mib_handler *handler)
  free's the resourceses associated with a given handler
netsnmp_mib_handler *  netsnmp_handler_dup (netsnmp_mib_handler *handler)
  dulpicates a handler and all subsequent handlers see also _clone_handler
void  netsnmp_handler_registration_free (netsnmp_handler_registration *reginfo)
  free the resources associated with a handler registration object
netsnmp_handler_registration *  netsnmp_handler_registration_dup (netsnmp_handler_registration *reginfo)
  duplicates the handler registration object
NETSNMP_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)
  creates a cache of information which can be saved for future reference.
NETSNMP_INLINE netsnmp_delegated_cache *  netsnmp_handler_check_cache (netsnmp_delegated_cache *dcache)
  check's a given cache and returns it if it is still valid (ie, the agent still considers it to be an outstanding request.
NETSNMP_INLINE void  netsnmp_free_delegated_cache (netsnmp_delegated_cache *dcache)
  frees a cache once you're finished using it
void  netsnmp_handler_mark_requests_as_delegated (netsnmp_request_info *requests, int isdelegated)
  marks a list of requests as delegated (or not if isdelegaded = 0)
NETSNMP_INLINE void  netsnmp_request_add_list_data (netsnmp_request_info *request, netsnmp_data_list *node)
  add data to a request that can be extracted later by submodules
NETSNMP_INLINE int  netsnmp_request_remove_list_data (netsnmp_request_info *request, const char *name)
  remove data from a request
NETSNMP_INLINE void *  netsnmp_request_get_list_data (netsnmp_request_info *request, const char *name)
  extract data from a request that was added previously by a parent module
NETSNMP_INLINE void  netsnmp_free_request_data_set (netsnmp_request_info *request)
  Free the extra data stored in a request.
NETSNMP_INLINE void  netsnmp_free_request_data_sets (netsnmp_request_info *request)
  Free the extra data stored in a bunch of requests (all data in the chain).
netsnmp_mib_handler *  netsnmp_find_handler_by_name (netsnmp_handler_registration *reginfo, const char *name)
  Returns a handler from a chain based on the name.
void *  netsnmp_find_handler_data_by_name (netsnmp_handler_registration *reginfo, const char *name)
  Returns a handler's void * pointer from a chain based on the name.
void  handler_free_callback (void *free)
void  netsnmp_register_handler_by_name (const char *name, netsnmp_mib_handler *handler)
  registers a given handler by name so that it can be found easily later.
void  netsnmp_clear_handler_list (void)
  clears the entire handler-registration list
void  netsnmp_inject_handler_into_subtree (netsnmp_subtree *tp, const char *name, netsnmp_mib_handler *handler, const char *before_what)
void  parse_injectHandler_conf (const char *token, char *cptr)
void  netsnmp_init_handler_conf (void)
void *  netsnmp_handler_get_parent_data (netsnmp_request_info *, const char *)

Detailed Description

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 created and then registered 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 instance, table, table_iterator, table_data, or table_dataset helpers to make their life easier. These "helpers" interpert important aspects of the request and pass them on to you.

For instance, the table helper is designed to hand you a list of extracted index values from an incoming request. THe table_iterator 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 table_iterator helper@, as well as the 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.

Typedef Documentation

struct netsnmp_handler_registration_s netsnmp_handler_registration
 

Typedefs the netsnmp_handler_registration_s struct into netsnmp_handler_registration.

Referenced by _data_lookup(), _netsnmp_stash_cache_load(), netsnmp_cache_handler_register(), netsnmp_cache_helper_handler(), netsnmp_call_handler(), netsnmp_call_next_handler(), netsnmp_call_next_handler_one_request(), netsnmp_create_delegated_cache(), netsnmp_find_handler_by_name(), netsnmp_find_handler_data_by_name(), netsnmp_find_table_array_handler(), netsnmp_find_table_registration_info(), netsnmp_generic_register(), netsnmp_generic_unregister(), netsnmp_handler_registration_create(), netsnmp_handler_registration_dup(), netsnmp_handler_registration_free(), netsnmp_inject_handler(), netsnmp_inject_handler_before(), netsnmp_instance_num_file_handler(), netsnmp_multiplexer_helper_handler(), netsnmp_old_api_helper(), netsnmp_register_cache_handler(), netsnmp_register_handler(), netsnmp_register_handler_nocallback(), netsnmp_register_instance(), netsnmp_register_int_instance(), netsnmp_register_mib_table_row(), netsnmp_register_old_api(), netsnmp_register_read_only_instance(), netsnmp_register_read_only_scalar(), netsnmp_register_read_only_table_data(), netsnmp_register_row_merge(), netsnmp_register_scalar(), netsnmp_register_serialize(), netsnmp_register_table(), netsnmp_register_table_data(), netsnmp_register_table_data_set(), netsnmp_register_table_iterator(), netsnmp_row_merge_helper_handler(), netsnmp_row_merge_status_first(), netsnmp_row_merge_status_get(), netsnmp_row_merge_status_last(), netsnmp_serialize_helper_handler(), netsnmp_sparse_table_register(), netsnmp_table_build_oid(), netsnmp_table_build_oid_from_index(), netsnmp_table_build_result(), netsnmp_table_container_register(), netsnmp_tdata_register(), netsnmp_unregister_handler(), and table_helper_handler().
struct netsnmp_mib_handler_s netsnmp_mib_handler
 

Typedefs the netsnmp_mib_handler_s struct into netsnmp_mib_handler.

Referenced by _netsnmp_stash_cache_load(), netsnmp_baby_steps_access_multiplexer_get(), netsnmp_baby_steps_handler_get(), netsnmp_cache_handler_get(), netsnmp_cache_handler_register(), netsnmp_cache_helper_handler(), netsnmp_call_handler(), netsnmp_call_next_handler(), netsnmp_call_next_handler_one_request(), netsnmp_container_table_handler_get(), netsnmp_create_delegated_cache(), netsnmp_create_handler(), netsnmp_find_handler_by_name(), netsnmp_find_handler_data_by_name(), netsnmp_find_table_array_handler(), netsnmp_generic_free_handler(), netsnmp_get_bulk_to_next_handler(), netsnmp_get_cache_handler(), netsnmp_get_mode_end_call_handler(), netsnmp_get_multiplexer_handler(), netsnmp_get_read_only_handler(), netsnmp_get_row_merge_handler(), netsnmp_get_stash_cache_handler(), netsnmp_get_stash_to_next_handler(), netsnmp_get_table_data_handler(), netsnmp_get_table_data_set_handler(), netsnmp_get_table_handler(), netsnmp_get_table_iterator_handler(), netsnmp_get_tdata_handler(), netsnmp_get_timed_bare_stash_cache_handler(), netsnmp_get_timed_stash_cache_handler(), netsnmp_handler_dup(), netsnmp_handler_free(), netsnmp_handler_registration_create(), netsnmp_inject_handler(), netsnmp_inject_handler_before(), netsnmp_instance_num_file_handler(), netsnmp_mode_end_call_add_mode_callback(), netsnmp_multiplexer_helper_handler(), netsnmp_old_api_helper(), netsnmp_register_cache_handler(), netsnmp_register_handler(), netsnmp_register_handler_by_name(), netsnmp_register_handler_nocallback(), netsnmp_row_merge_helper_handler(), netsnmp_serialize_helper_handler(), and table_helper_handler().

Function Documentation

int netsnmp_call_handler (  netsnmp_mib_handler *  next_handler,
netsnmp_handler_registration *  reginfo,
netsnmp_agent_request_info *  reqinfo,
netsnmp_request_info *  requests
) 
 

calls a handler with with appropriate NULL checking of arguments, etc.

Definition at line 387 of file agent_handler.c.

References netsnmp_mib_handler_s::access_method, netsnmp_mib_handler_s::flags, netsnmp_mib_handler_s::handler_name, netsnmp_agent_request_info_s::mode, netsnmp_handler_registration, netsnmp_mib_handler, netsnmp_mib_handler_s::next, and snmp_log().

Referenced by netsnmp_call_next_handler(), netsnmp_call_next_handler_one_request(), and netsnmp_multiplexer_helper_handler().
int netsnmp_call_next_handler (  netsnmp_mib_handler *  current,
netsnmp_handler_registration *  reginfo,
netsnmp_agent_request_info *  reqinfo,
netsnmp_request_info *  requests
) 
 

calls the next handler in the chain after the current one with with appropriate NULL checking, etc.

Definition at line 517 of file agent_handler.c.

References netsnmp_call_handler(), netsnmp_handler_registration, netsnmp_mib_handler, netsnmp_mib_handler_s::next, and snmp_log().

Referenced by _netsnmp_stash_cache_load(), netsnmp_instance_num_file_handler(), netsnmp_row_merge_helper_handler(), netsnmp_serialize_helper_handler(), and table_helper_handler().
int netsnmp_call_next_handler_one_request (  netsnmp_mib_handler *  current,
netsnmp_handler_registration *  reginfo,
netsnmp_agent_request_info *  reqinfo,
netsnmp_request_info *  requests
) 
 

calls the next handler in the chain after the current one with with appropriate NULL checking, etc.

Definition at line 539 of file agent_handler.c.

References netsnmp_call_handler(), netsnmp_handler_registration, netsnmp_mib_handler, netsnmp_mib_handler_s::next, netsnmp_request_info_s::next, and snmp_log().
void netsnmp_clear_handler_list (  void   ) 
 

clears the entire handler-registration list

Definition at line 897 of file agent_handler.c.

References netsnmp_free_all_list_data().
NETSNMP_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
) 
 

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.

Examples:
delayed_instance.c.

Definition at line 688 of file agent_handler.c.

References netsnmp_agent_request_info_s::asp, netsnmp_handler_registration, netsnmp_mib_handler, and SNMP_MALLOC_TYPEDEF.
netsnmp_mib_handler * netsnmp_create_handler (  const char *  name,
Netsnmp_Node_Handler *  handler_access_method
) 
 

creates a netsnmp_mib_handler structure given a name and a access method.

The returned handler should then be registered.

Parameters:
name  is the handler name and is copied then assigned to netsnmp_mib_handler->handler_name
handler_access_method  is a function pointer used as the access method for this handler registration instance for whatever required needs.
Returns:
a pointer to a populated netsnmp_mib_handler struct to be registered
See also:
netsnmp_create_handler_registration()

netsnmp_register_handler()

Definition at line 105 of file agent_handler.c.

References netsnmp_mib_handler_s::access_method, netsnmp_mib_handler_s::handler_name, netsnmp_mib_handler, SNMP_FREE, and SNMP_MALLOC_TYPEDEF.

Referenced by get_old_api_handler(), netsnmp_baby_steps_access_multiplexer_get(), netsnmp_baby_steps_handler_get(), netsnmp_cache_handler_get(), netsnmp_container_table_handler_get(), netsnmp_get_bulk_to_next_handler(), netsnmp_get_debug_handler(), netsnmp_get_instance_handler(), netsnmp_get_mode_end_call_handler(), netsnmp_get_multiplexer_handler(), netsnmp_get_read_only_handler(), netsnmp_get_row_merge_handler(), netsnmp_get_scalar_handler(), netsnmp_get_serialize_handler(), netsnmp_get_stash_to_next_handler(), netsnmp_get_table_data_handler(), netsnmp_get_table_data_set_handler(), netsnmp_get_table_handler(), netsnmp_get_table_iterator_handler(), netsnmp_get_tdata_handler(), netsnmp_get_timed_bare_stash_cache_handler(), netsnmp_sparse_table_handler_get(), and netsnmp_sparse_table_register().
netsnmp_mib_handler * netsnmp_find_handler_by_name (  netsnmp_handler_registration *  reginfo,
const char *  name
) 
 

Returns a handler from a chain based on the name.

Definition at line 830 of file agent_handler.c.

References netsnmp_handler_registration_s::handler, netsnmp_mib_handler_s::handler_name, netsnmp_handler_registration, netsnmp_mib_handler, and netsnmp_mib_handler_s::next.

Referenced by netsnmp_find_handler_data_by_name().
void * netsnmp_find_handler_data_by_name (  netsnmp_handler_registration *  reginfo,
const char *  name
) 
 

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.

Definition at line 847 of file agent_handler.c.

References netsnmp_mib_handler_s::myvoid, netsnmp_find_handler_by_name(), netsnmp_handler_registration, and netsnmp_mib_handler.

Referenced by netsnmp_find_table_registration_info().
NETSNMP_INLINE void netsnmp_free_delegated_cache (  netsnmp_delegated_cache *  dcache  ) 
 

frees a cache once you're finished using it

Examples:
delayed_instance.c.

Definition at line 726 of file agent_handler.c.

References SNMP_FREE.
NETSNMP_INLINE void netsnmp_free_request_data_set (  netsnmp_request_info *  request  ) 
 

Free the extra data stored in a request.

Definition at line 812 of file agent_handler.c.

References netsnmp_free_list_data(), and netsnmp_request_info_s::parent_data.
NETSNMP_INLINE void netsnmp_free_request_data_sets (  netsnmp_request_info *  request  ) 
 

Free the extra data stored in a bunch of requests (all data in the chain).

Definition at line 820 of file agent_handler.c.

References netsnmp_free_all_list_data(), and netsnmp_request_info_s::parent_data.

Referenced by netsnmp_add_varbind_to_cache().
NETSNMP_INLINE netsnmp_delegated_cache * netsnmp_handler_check_cache (  netsnmp_delegated_cache *  dcache  ) 
 

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.

Examples:
delayed_instance.c.

Definition at line 712 of file agent_handler.c.

References netsnmp_check_transaction_id().
netsnmp_mib_handler * netsnmp_handler_dup (  netsnmp_mib_handler *  handler  ) 
 

dulpicates a handler and all subsequent handlers see also _clone_handler

Definition at line 584 of file agent_handler.c.

References netsnmp_mib_handler_s::myvoid, netsnmp_handler_free(), netsnmp_mib_handler, netsnmp_mib_handler_s::next, and netsnmp_mib_handler_s::prev.

Referenced by netsnmp_handler_registration_dup().
void netsnmp_handler_free (  netsnmp_mib_handler *  handler  ) 
 

free's the resourceses associated with a given handler

make sure we aren't pointing to ourselves.

XXX : segv here at shutdown if SHUTDOWN_AGENT_CLEANLY defined. About 30 functions down the stack, starting in clear_context() -> clear_subtree()

Definition at line 562 of file agent_handler.c.

References netsnmp_mib_handler_s::handler_name, netsnmp_mib_handler, netsnmp_mib_handler_s::next, and SNMP_FREE.

Referenced by netsnmp_baby_steps_handler_get(), netsnmp_handler_dup(), and netsnmp_handler_registration_free().
void netsnmp_handler_mark_requests_as_delegated (  netsnmp_request_info *  requests,
int  isdelegated
) 
 

marks a list of requests as delegated (or not if isdelegaded = 0)

Definition at line 740 of file agent_handler.c.

References netsnmp_request_info_s::delegated, and netsnmp_request_info_s::next.
netsnmp_handler_registration * netsnmp_handler_registration_create (  const char *  name,
netsnmp_mib_handler *  handler,
oid *  reg_oid,
size_t  reg_oid_len,
int  modes
) 
 

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. A hander which supports sets but not row creation should set us a mode of HANDLER_CAN_SET_ONLY.

Note:
This ends up calling netsnmp_create_handler(name, handler_access_method)
Parameters:
name  is the handler name and is copied then assigned to netsnmp_handler_registration->handlerName.
handler_access_method  is a function pointer used as the access method for this handler registration instance for whatever required needs.
reg_oid  is the registration location oid.
reg_oid_len  is the length of reg_oid, can use the macro, OID_LENGTH
modes  is used to configure read/write access. 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. The other two mode options are read only, HANDLER_CAN_RONLY, and read/write, HANDLER_CAN_RWRITE.
  • HANDLER_CAN_GETANDGETNEXT
  • HANDLER_CAN_SET
  • HANDLER_CAN_GETBULK
  • HANDLER_CAN_RONLY (HANDLER_CAN_GETANDGETNEXT)
  • HANDLER_CAN_RWRITE (HANDLER_CAN_GETANDGETNEXT | HANDLER_CAN_SET)
  • HANDLER_CAN_DEFAULT HANDLER_CAN_RONLY
Returns:
Returns a pointer to a netsnmp_handler_registration struct. NULL is returned only when memory could not be allocated for the netsnmp_handler_registration struct.
See also:
netsnmp_create_handler()

netsnmp_register_handler()

Definition at line 163 of file agent_handler.c.

References netsnmp_handler_registration_s::handler, netsnmp_handler_registration_s::handlerName, memdup(), netsnmp_handler_registration_s::modes, netsnmp_handler_registration, netsnmp_mib_handler, netsnmp_handler_registration_s::priority, netsnmp_handler_registration_s::rootoid, netsnmp_handler_registration_s::rootoid_len, and SNMP_MALLOC_TYPEDEF.
netsnmp_handler_registration * netsnmp_handler_registration_dup (  netsnmp_handler_registration *  reginfo  ) 
 

duplicates the handler registration object

Definition at line 626 of file agent_handler.c.

References netsnmp_handler_registration_s::contextName, netsnmp_handler_registration_s::handler, netsnmp_handler_registration_s::handlerName, memdup(), netsnmp_handler_registration_s::modes, netsnmp_handler_dup(), netsnmp_handler_registration, netsnmp_handler_registration_free(), netsnmp_handler_registration_s::priority, netsnmp_handler_registration_s::range_subid, netsnmp_handler_registration_s::range_ubound, netsnmp_handler_registration_s::rootoid, netsnmp_handler_registration_s::rootoid_len, and netsnmp_handler_registration_s::timeout.
void netsnmp_handler_registration_free (  netsnmp_handler_registration *  reginfo  ) 
 

free the resources associated with a handler registration object

Definition at line 613 of file agent_handler.c.

References netsnmp_handler_registration_s::contextName, netsnmp_handler_registration_s::handler, netsnmp_handler_registration_s::handlerName, netsnmp_handler_free(), netsnmp_handler_registration, netsnmp_handler_registration_s::rootoid, and SNMP_FREE.

Referenced by netsnmp_handler_registration_dup(), and netsnmp_register_mib_table_row().
int netsnmp_inject_handler (  netsnmp_handler_registration *  reginfo,
netsnmp_mib_handler *  handler
) 
 

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.

Definition at line 379 of file agent_handler.c.

References netsnmp_handler_registration, netsnmp_inject_handler_before(), and netsnmp_mib_handler.

Referenced by netsnmp_cache_handler_register(), netsnmp_register_cache_handler(), netsnmp_register_handler(), netsnmp_register_instance(), netsnmp_register_read_only_instance(), netsnmp_register_read_only_scalar(), netsnmp_register_read_only_table_data(), netsnmp_register_row_merge(), netsnmp_register_scalar(), netsnmp_register_serialize(), netsnmp_register_table(), netsnmp_register_table_data(), netsnmp_register_table_data_set(), netsnmp_register_table_iterator(), netsnmp_sparse_table_register(), and netsnmp_tdata_register().
int netsnmp_inject_handler_before (  netsnmp_handler_registration *  reginfo,
netsnmp_mib_handler *  handler,
const char *  before_what
) 
 

inject a new handler into the calling chain of the handlers definedy by the netsnmp_handler_registration pointer.

The new handler is injected after the before_what handler, or if NULL at the top of the list and hence will be the new handler to be called first.

Definition at line 322 of file agent_handler.c.

References netsnmp_handler_registration_s::handler, netsnmp_mib_handler_s::handler_name, netsnmp_handler_registration, netsnmp_mib_handler, netsnmp_mib_handler_s::next, netsnmp_mib_handler_s::prev, and snmp_log().

Referenced by netsnmp_inject_handler().
int netsnmp_register_handler (  netsnmp_handler_registration *  reginfo  ) 
 

register a handler, as defined by the netsnmp_handler_registration pointer.

Definition at line 202 of file agent_handler.c.

References netsnmp_handler_registration_s::contextName, netsnmp_handler_registration_s::handler, netsnmp_mib_handler_s::handler_name, netsnmp_handler_registration_s::handlerName, netsnmp_handler_registration_s::modes, netsnmp_get_bulk_to_next_handler(), netsnmp_handler_registration, netsnmp_inject_handler(), netsnmp_mib_handler, netsnmp_mib_handler_s::next, netsnmp_handler_registration_s::priority, netsnmp_handler_registration_s::range_subid, netsnmp_handler_registration_s::range_ubound, netsnmp_handler_registration_s::rootoid, netsnmp_handler_registration_s::rootoid_len, snmp_log(), and netsnmp_handler_registration_s::timeout.

Referenced by netsnmp_cache_handler_register(), netsnmp_register_cache_handler(), netsnmp_register_old_api(), netsnmp_register_row_merge(), netsnmp_register_serialize(), netsnmp_register_table(), and netsnmp_sparse_table_register().
void netsnmp_register_handler_by_name (  const char *  name,
netsnmp_mib_handler *  handler
) 
 

registers a given handler by name so that it can be found easily later.

Definition at line 885 of file agent_handler.c.

References netsnmp_add_list_data(), netsnmp_create_data_list(), and netsnmp_mib_handler.

Referenced by netsnmp_baby_steps_handler_init(), netsnmp_init_bulk_to_next_helper(), netsnmp_init_debug_helper(), netsnmp_init_read_only_helper(), netsnmp_init_row_merge(), netsnmp_init_serialize(), and netsnmp_init_stash_cache_helper().
int netsnmp_register_handler_nocallback (  netsnmp_handler_registration *  reginfo  ) 
 

register a handler, as defined by the netsnmp_handler_registration pointer.

Definition at line 270 of file agent_handler.c.

References netsnmp_handler_registration_s::contextName, netsnmp_handler_registration_s::handler, netsnmp_mib_handler_s::handler_name, netsnmp_handler_registration_s::modes, netsnmp_handler_registration, netsnmp_mib_handler, netsnmp_mib_handler_s::next, netsnmp_handler_registration_s::priority, netsnmp_handler_registration_s::range_subid, netsnmp_handler_registration_s::range_ubound, netsnmp_handler_registration_s::rootoid, netsnmp_handler_registration_s::rootoid_len, snmp_log(), and netsnmp_handler_registration_s::timeout.

Referenced by netsnmp_register_mib_table_row().
NETSNMP_INLINE void netsnmp_request_add_list_data (  netsnmp_request_info *  request,
netsnmp_data_list *  node
) 
 

add data to a request that can be extracted later by submodules

Parameters:
requset  the netsnmp request info structure
node  this is the data to be added to the linked list request->parent_data
Returns:
void
Examples:
delayed_instance.c.

Definition at line 760 of file agent_handler.c.

References netsnmp_add_list_data(), and netsnmp_request_info_s::parent_data.

Referenced by _data_lookup(), netsnmp_container_table_row_insert(), netsnmp_insert_iterator_context(), netsnmp_insert_table_row(), netsnmp_instance_num_file_handler(), netsnmp_old_api_helper(), and table_helper_handler().
NETSNMP_INLINE void * netsnmp_request_get_list_data (  netsnmp_request_info *  request,
const char *  name
) 
 

extract data from a request that was added previously by a parent module

Parameters:
request  the netsnmp request info function
name  used to compare against the request->parent_data->name value, if a match is found request->parent_data->data is returned
Returns:
a void pointer(request->parent_data->data), otherwise NULL is returned if request is NULL or request->parent_data is NULL or request->parent_data object is not found.
Examples:
delayed_instance.c.

Definition at line 802 of file agent_handler.c.

References netsnmp_get_list_data(), and netsnmp_request_info_s::parent_data.

Referenced by netsnmp_container_table_container_extract(), netsnmp_container_table_extract_context(), netsnmp_container_table_row_extract(), netsnmp_extract_array_context(), netsnmp_extract_iterator_context(), netsnmp_extract_table(), netsnmp_extract_table_data_set(), netsnmp_extract_table_info(), netsnmp_extract_table_row(), netsnmp_instance_num_file_handler(), netsnmp_old_api_helper(), netsnmp_tdata_extract_container(), and netsnmp_tdata_extract_table().
NETSNMP_INLINE int netsnmp_request_remove_list_data (  netsnmp_request_info *  request,
const char *  name
) 
 

remove data from a request

Parameters:
requset  the netsnmp request info structure
name  this is the name of the previously added data
Returns:
0 on successful find-and-delete, 1 otherwise.

Definition at line 781 of file agent_handler.c.

References