The Net-SNMP library

Data Structures
struct	snmp_internal_session
Modules
	asn1 parsing and datatype manipulation routines.
	Note on.
	A generic callback mechanism
	generic linked-list data handling with a string as a key.
	storage space for defaults
	The purpose of the default storage is three-fold:
	mib parsing and datatype manipulation routines.
	Store and retrieve data referenced by an OID.
	This is essentially a way of storing data associated with a given OID.
	parsing various configuration files at run time
	The read_config related functions are a fairly extensible system of parsing various configuration files at the run time.
	generic library based alarm timers for various parts of an application
	various PDU processing routines
	generic logging for net-snmp
	Memory Utility Routines
Defines
#define	MIN(a, b)   (((a) < (b)) ? (a) : (b))
#define	MIB_CLIENTS_ARE_EVIL   1
#define	_init_agent_callback_transport()
#define	SNMP_NEED_REQUEST_LIST
#define	DEFAULT_COMMUNITY   "public"
#define	DEFAULT_RETRIES   5
#define	DEFAULT_TIMEOUT   ONE_SEC
#define	DEFAULT_REMPORT   SNMP_PORT
#define	DEFAULT_ENTERPRISE   default_enterprise
#define	DEFAULT_TIME   0
#define	MAXIMUM_PACKET_SIZE   0x7fffffff
#define	DEBUGPRINTPDUTYPE(token, type)   DEBUGDUMPSECTION(token, snmp_pdu_type(type))
#define	ERROR_STAT_LENGTH   11
Functions
int	init_agent (const char *app)
	Initialize the agent.
void	shutdown_agent (void)
void	add_to_init_list (char *module_list)
int	should_init (const char *module_name)
	netsnmp_feature_child_of (statistics, libnetsnmp)
int	snmp_build (u_char **pkt, size_t *pkt_len, size_t *offset, netsnmp_session *pss, netsnmp_pdu *pdu)
int	snmp_get_errno (void)
NETSNMP_IMPORT void	snmp_synch_reset (netsnmp_session *notused)
NETSNMP_IMPORT void	snmp_synch_setup (netsnmp_session *notused)
const char *	strerror (int err)
const char *	snmp_pdu_type (int type)
long	snmp_get_next_reqid (void)
long	snmp_get_next_msgid (void)
long	snmp_get_next_sessid (void)
long	snmp_get_next_transid (void)
void	snmp_perror (const char *prog_string)
void	snmp_set_detail (const char *detail_string)
const char *	snmp_api_errstring (int snmp_errnumber)
void	snmp_error (netsnmp_session *psess, int *p_errno, int *p_snmp_errno, char **p_str)
	Library API routines concerned with logging and message output (including error handling and debugging).
void	snmp_sess_error (void *sessp, int *p_errno, int *p_snmp_errno, char **p_str)
void	netsnmp_sess_log_error (int priority, const char *prog_string, netsnmp_session *ss)
void	snmp_sess_perror (const char *prog_string, netsnmp_session *ss)
void	snmp_sess_init (netsnmp_session *session)
	Library API routines concerned with specifying and using SNMP "sessions" including sending and receiving requests.
void	init_snmp (const char *type)
	Calls the functions to do config file loading and mib module parsing in the correct order.
void	snmp_store_needed (const char *type)
	set a flag indicating that the persistent store needs to be saved.
void	snmp_store_if_needed (void)
void	snmp_store (const char *type)
void	snmp_shutdown (const char *type)
	Shuts down the application, saving any needed persistent storage, and appropriate clean up.
netsnmp_session *	snmp_open (netsnmp_session *session)
	netsnmp_feature_child_of (snmp_open_ex, netsnmp_unused)
int	snmpv3_probe_contextEngineID_rfc5343 (void *slp, netsnmp_session *session)
	probe for engineID using RFC 5343 probing mechanisms
int	snmpv3_engineID_probe (struct session_list *slp, netsnmp_session *in_session)
	probe for peer engineID
int	netsnmp_sess_config_transport (netsnmp_container *transport_configuration, netsnmp_transport *transport)
int	netsnmp_sess_config_and_open_transport (netsnmp_session *in_session, netsnmp_transport *transport)
	Copies configuration from the session and calls f_open This function copies any configuration stored in the session pointer to the transport if it has a f_config pointer and then calls the transport's f_open function to actually open the connection.
netsnmp_session *	snmp_add (netsnmp_session *in_session, netsnmp_transport *transport, int(*fpre_parse)(netsnmp_session *, netsnmp_transport *, void *, int), int(*fpost_parse)(netsnmp_session *, netsnmp_pdu *, int))
netsnmp_session *	snmp_add_full (netsnmp_session *in_session, netsnmp_transport *transport, int(*fpre_parse)(netsnmp_session *, netsnmp_transport *, void *, int), int(*fparse)(netsnmp_session *, netsnmp_pdu *, u_char *, size_t), int(*fpost_parse)(netsnmp_session *, netsnmp_pdu *, int), int(*fbuild)(netsnmp_session *, netsnmp_pdu *, u_char *, size_t *), int(*frbuild)(netsnmp_session *, netsnmp_pdu *, u_char **, size_t *, size_t *), int(*fcheck)(u_char *, size_t), netsnmp_pdu *(*fcreate_pdu)(netsnmp_transport *, void *, size_t))
void *	snmp_sess_add_ex (netsnmp_session *in_session, netsnmp_transport *transport, int(*fpre_parse)(netsnmp_session *, netsnmp_transport *, void *, int), int(*fparse)(netsnmp_session *, netsnmp_pdu *, u_char *, size_t), int(*fpost_parse)(netsnmp_session *, netsnmp_pdu *, int), int(*fbuild)(netsnmp_session *, netsnmp_pdu *, u_char *, size_t *), int(*frbuild)(netsnmp_session *, netsnmp_pdu *, u_char **, size_t *, size_t *), int(*fcheck)(u_char *, size_t), netsnmp_pdu *(*fcreate_pdu)(netsnmp_transport *, void *, size_t))
void *	snmp_sess_add (netsnmp_session *in_session, netsnmp_transport *transport, int(*fpre_parse)(netsnmp_session *, netsnmp_transport *, void *, int), int(*fpost_parse)(netsnmp_session *, netsnmp_pdu *, int))
void *	snmp_sess_open (netsnmp_session *pss)
int	create_user_from_session (netsnmp_session *session)
int	snmp_sess_close (void *sessp)
int	snmp_close (netsnmp_session *session)
int	snmp_close_sessions (void)
int	snmpv3_packet_build (netsnmp_session *session, netsnmp_pdu *pdu, u_char *packet, size_t *out_length, u_char *pdu_data, size_t pdu_data_len)
u_char *	snmp_pdu_build (netsnmp_pdu *pdu, u_char *cp, size_t *out_length)
int	snmpv3_parse (netsnmp_pdu *pdu, u_char *data, size_t *length, u_char **after_header, netsnmp_session *sess)
int	snmpv3_make_report (netsnmp_pdu *pdu, int error)
int	snmpv3_get_report_type (netsnmp_pdu *pdu)
int	snmp_pdu_parse (netsnmp_pdu *pdu, u_char *data, size_t *length)
u_char *	snmpv3_scopedPDU_parse (netsnmp_pdu *pdu, u_char *cp, size_t *length)
int	snmp_send (netsnmp_session *session, netsnmp_pdu *pdu)
int	snmp_sess_send (void *sessp, netsnmp_pdu *pdu)
int	snmp_async_send (netsnmp_session *session, netsnmp_pdu *pdu, snmp_callback callback, void *cb_data)
int	snmp_sess_async_send (void *sessp, netsnmp_pdu *pdu, snmp_callback callback, void *cb_data)
void	snmp_free_var_internals (netsnmp_variable_list *var)
void	snmp_free_var (netsnmp_variable_list *var)
void	snmp_free_varbind (netsnmp_variable_list *var)
void	snmp_free_pdu (netsnmp_pdu *pdu)
netsnmp_pdu *	snmp_create_sess_pdu (netsnmp_transport *transport, void *opaque, size_t olength)
void	snmp_read (fd_set *fdset)
void	snmp_read2 (netsnmp_large_fd_set *fdset)
int	_sess_read (void *sessp, netsnmp_large_fd_set *fdset)
int	snmp_sess_read (void *sessp, fd_set *fdset)
int	snmp_sess_read2 (void *sessp, netsnmp_large_fd_set *fdset)
int	snmp_select_info (int *numfds, fd_set *fdset, struct timeval *timeout, int *block)
int	snmp_select_info2 (int *numfds, netsnmp_large_fd_set *fdset, struct timeval *timeout, int *block)
int	snmp_sess_select_info (void *sessp, int *numfds, fd_set *fdset, struct timeval *timeout, int *block)
int	snmp_sess_select_info_flags (void *sessp, int *numfds, fd_set *fdset, struct timeval *timeout, int *block, int flags)
int	snmp_sess_select_info2 (void *sessp, int *numfds, netsnmp_large_fd_set *fdset, struct timeval *timeout, int *block)
int	snmp_sess_select_info2_flags (void *sessp, int *numfds, netsnmp_large_fd_set *fdset, struct timeval *timeout, int *block, int flags)
void	snmp_timeout (void)
void	snmp_sess_timeout (void *sessp)
int	snmp_oid_ncompare (const oid *in_name1, size_t len1, const oid *in_name2, size_t len2, size_t max_len)
int	snmp_oid_compare (const oid *in_name1, size_t len1, const oid *in_name2, size_t len2)
	lexicographical compare two object identifiers.
int	netsnmp_oid_compare_ll (const oid *in_name1, size_t len1, const oid *in_name2, size_t len2, size_t *offpt)
	lexicographical compare two object identifiers and return the point where they differ
int	snmp_oidtree_compare (const oid *in_name1, size_t len1, const oid *in_name2, size_t len2)
	Compares 2 OIDs to determine if they are equal up until the shortest length.
int	snmp_oidsubtree_compare (const oid *in_name1, size_t len1, const oid *in_name2, size_t len2)
int	netsnmp_oid_equals (const oid *in_name1, size_t len1, const oid *in_name2, size_t len2)
	Compares 2 OIDs to determine if they are exactly equal.
int	netsnmp_oid_is_subtree (const oid *in_name1, size_t len1, const oid *in_name2, size_t len2)
	Identical to netsnmp_oid_equals, except only the length up to len1 is compared.
int	netsnmp_oid_find_prefix (const oid *in_name1, size_t len1, const oid *in_name2, size_t len2)
	Given two OIDs, determine the common prefix to them both.
netsnmp_variable_list *	snmp_pdu_add_variable (netsnmp_pdu *pdu, const oid *name, size_t name_length, u_char type, const void *value, size_t len)
	Library API routines concerned with variable bindings and values.
netsnmp_variable_list *	snmp_varlist_add_variable (netsnmp_variable_list **varlist, const oid *name, size_t name_length, u_char type, const void *value, size_t len)
int	snmp_add_var (netsnmp_pdu *pdu, const oid *name, size_t name_length, char type, const char *value)
void *	snmp_sess_pointer (netsnmp_session *session)
netsnmp_session *	snmp_sess_session (void *sessp)
netsnmp_session *	snmp_sess_session_lookup (void *sessp)
	Look up a session that already may have been closed.
netsnmp_transport *	snmp_sess_transport (void *sessp)
void	snmp_sess_transport_set (void *sp, netsnmp_transport *t)
oid *	snmp_duplicate_objid (const oid *objToCopy, size_t objToCopyLen)
u_int	snmp_increment_statistic (int which)
u_int	snmp_increment_statistic_by (int which, int count)
u_int	snmp_get_statistic (int which)
void	snmp_init_statistics (void)
Variables
struct module_init_list *	initlist = NULL
struct module_init_list *	noinitlist = NULL
netsnmp_subtree *	subtrees
long	long_return
u_char	return_buf [258]
int	callback_master_num = -1
oid	nullOid [] = { 0, 0 }
int	nullOidLen = sizeof(nullOid)
struct session_list *	Sessions = NULL
int	snmp_errno = 0

---

Function Documentation

int _sess_read	(	void *	sessp,
		netsnmp_large_fd_set *	fdset
	)

XXX-rks: why no SNMP_FREE(isp->packet); ??

XXX-rks: why no SNMP_FREE(isp->packet); ??

Definition at line 5482 of file snmp_api.c.

int init_agent

(

const char *

app

)

Initialize the agent.

Calls into init_agent_read_config to set tha app's configuration file in the appropriate default storage space, NETSNMP_DS_LIB_APPTYPE. Need to call init_agent before calling init_snmp.

Parameters:

app	the configuration file to be read in, gets stored in default storage

Returns:

Returns non-zero on failure and zero on success.

See also:

init_snmp

Definition at line 270 of file snmp_vars.c.

void init_snmp

(

const char *

type

)

Calls the functions to do config file loading and mib module parsing in the correct order.

Parameters:

type	label for the config file "type"

Returns:

void

See also:

init_agent

Definition at line 803 of file snmp_api.c.

int netsnmp_oid_compare_ll	(	const oid *	in_name1,
		size_t	len1,
		const oid *	in_name2,
		size_t	len2,
		size_t *	offpt
	)

lexicographical compare two object identifiers and return the point where they differ

Caution: this method is called often by command responder applications (ie, agent).

Returns:

-1 if name1 < name2, 0 if name1 = name2, 1 if name1 > name2 and offpt = len where name1 != name2

Definition at line 6478 of file snmp_api.c.

int netsnmp_oid_equals	(	const oid *	in_name1,
		size_t	len1,
		const oid *	in_name2,
		size_t	len2
	)

Compares 2 OIDs to determine if they are exactly equal.

This should be faster than doing a snmp_oid_compare for different length OIDs, since the length is checked first and if != returns immediately. Might be very slighly faster if lengths are ==.

Parameters:

in_name1	A pointer to the first oid.
len1	length of the first OID (in segments, not bytes)
in_name2	A pointer to the second oid.
len2	length of the second OID (in segments, not bytes)

Returns:

0 if they are equal, 1 if they are not.

Definition at line 6559 of file snmp_api.c.

int netsnmp_oid_find_prefix	(	const oid *	in_name1,
		size_t	len1,
		const oid *	in_name2,
		size_t	len2
	)

Given two OIDs, determine the common prefix to them both.

Parameters:

in_name1	A pointer to the first oid.
len1	Length of the first oid.
in_name2	A pointer to the second oid.
len2	Length of the second oid.

Returns:

length of common prefix 0 if no common prefix, -1 on error.

Definition at line 6625 of file snmp_api.c.

int netsnmp_oid_is_subtree	(	const oid *	in_name1,
		size_t	len1,
		const oid *	in_name2,
		size_t	len2
	)

Identical to netsnmp_oid_equals, except only the length up to len1 is compared.

Functionally, this determines if in_name2 is equal or a subtree of in_name1

Parameters:

in_name1	A pointer to the first oid.
len1	length of the first OID (in segments, not bytes)
in_name2	A pointer to the second oid.
len2	length of the second OID (in segments, not bytes)

Returns:

0 if one is a common prefix of the other.

Definition at line 6603 of file snmp_api.c.

int netsnmp_sess_config_and_open_transport	(	netsnmp_session *	in_session,
		netsnmp_transport *	transport
	)

Copies configuration from the session and calls f_open This function copies any configuration stored in the session pointer to the transport if it has a f_config pointer and then calls the transport's f_open function to actually open the connection.

Parameters:

in_session	A pointer to the session that config information is in.
transport	A pointer to the transport to config/open.

Returns:

SNMPERR_SUCCESS : on success

Definition at line 1476 of file snmp_api.c.

void snmp_error	(	netsnmp_session *	psess,
		int *	p_errno,
		int *	p_snmp_errno,
		char **	p_str
	)

Library API routines concerned with logging and message output (including error handling and debugging).

Definition at line 550 of file snmp_api.c.

int snmp_oid_compare	(	const oid *	in_name1,
		size_t	len1,
		const oid *	in_name2,
		size_t	len2
	)

lexicographical compare two object identifiers.

Caution: this method is called often by command responder applications (ie, agent).

Returns:

-1 if name1 < name2, 0 if name1 = name2, 1 if name1 > name2

Definition at line 6429 of file snmp_api.c.

int snmp_oidtree_compare	(	const oid *	in_name1,
		size_t	len1,
		const oid *	in_name2,
		size_t	len2
	)

Compares 2 OIDs to determine if they are equal up until the shortest length.

Parameters:

in_name1	A pointer to the first oid.
len1	length of the first OID (in segments, not bytes)
in_name2	A pointer to the second oid.
len2	length of the second OID (in segments, not bytes)

Returns:

0 if they are equal, 1 if in_name1 is > in_name2, or -1 if <.

Definition at line 6531 of file snmp_api.c.

netsnmp_variable_list* snmp_pdu_add_variable	(	netsnmp_pdu *	pdu,
		const oid *	name,
		size_t	name_length,
		u_char	type,
		const void *	value,
		size_t	len
	)

Library API routines concerned with variable bindings and values.

Definition at line 6696 of file snmp_api.c.

void snmp_sess_init

(

netsnmp_session *

session

)

Library API routines concerned with specifying and using SNMP "sessions" including sending and receiving requests.

Definition at line 721 of file snmp_api.c.

netsnmp_session* snmp_sess_session_lookup

(

void *

sessp

)

Look up a session that already may have been closed.

Parameters:

sessp

Opaque pointer, returned by snmp_sess_open.

Returns:

Pointer to session upon success or NULL upon failure.

See also:

snmp_sess_session()

Definition at line 7289 of file snmp_api.c.

void snmp_shutdown

(

const char *

type

)

Shuts down the application, saving any needed persistent storage, and appropriate clean up.

Parameters:

type	Label for the config file "type" used

Returns:

void

Definition at line 900 of file snmp_api.c.

void snmp_store_needed

(

const char *

type

)

set a flag indicating that the persistent store needs to be saved.

Definition at line 863 of file snmp_api.c.

int snmpv3_engineID_probe	(	struct session_list *	slp,
		netsnmp_session *	in_session
	)

probe for peer engineID

Parameters:

slp	session list pointer.
in_session	session for errors

Note:

• called by _sess_open(), snmp_sess_add_ex()
• in_session is the user supplied session provided to those functions.
• the first session in slp should the internal allocated copy of in_session

Returns:

0 : error

1 : ok

Definition at line 1357 of file snmp_api.c.

int snmpv3_probe_contextEngineID_rfc5343	(	void *	slp,
		netsnmp_session *	session
	)

probe for engineID using RFC 5343 probing mechanisms

Designed to be a callback for within a security model's probe_engineid hook. Since it's likely multiple security models won't have engineIDs to probe for then this function is a callback likely to be used by multiple future security models. E.G. both SSH and DTLS.

Definition at line 1259 of file snmp_api.c.