netsnmp_agent_api - embedding an agent into a external application
#include <net-snmp/net-snmp-config.h>
#include <net-snmp/net-snmp-includes.h>
#include <net-snmp/agent/net-snmp-agent-includes.h>
int
main (int argc, char *argv[])
{
int agentx_subagent = 1; /* Change this if you're a master agent. */
snmp_enable_stderrlog();
/* If we're an AgentX subagent... */
if (agentx_subagent) {
/* ...make us an AgentX client. */
netsnmp_ds_set_boolean(NETSNMP_DS_APPLICATION_ID,
NETSNMP_DS_AGENT_ROLE, 1);
}
init_agent("yourappname");
/* Initialize your MIB code here. */
init_my_mib_code();
/* `yourappname' will be used to read yourappname.conf files. */
init_snmp("yourappname");
/* If we're going to be a SNMP master agent... */
if (!agentx_subagent)
init_master_agent(); /* Listen on default port (161). */
/* Your main loop here... */
while (whatever) {
/* if you use select(), see snmp_api(3) */
/* --- OR --- */
agent_check_and_process(0); /* 0 == don't block */
}
/* At shutdown time: */
snmp_shutdown("yourappname");
}
Then:
$(CC) ... `net-snmp-config --agent-libs`
NETSNMP_AGENT_API(3) Net-SNMP NETSNMP_AGENT_API(3)
NAME
netsnmp_agent_api - embedding an agent into a external application
SYNOPSIS
#include <net-snmp/net-snmp-config.h>
#include <net-snmp/net-snmp-includes.h>
#include <net-snmp/agent/net-snmp-agent-includes.h>
int
main (int argc, char *argv[])
{
int agentx_subagent = 1; /* Change this if you're a master agent. */
snmp_enable_stderrlog();
/* If we're an AgentX subagent... */
if (agentx_subagent) {
/* ...make us an AgentX client. */
netsnmp_ds_set_boolean(NETSNMP_DS_APPLICATION_ID,
NETSNMP_DS_AGENT_ROLE, 1);
}
init_agent("yourappname");
/* Initialize your MIB code here. */
init_my_mib_code();
/* `yourappname' will be used to read yourappname.conf files. */
init_snmp("yourappname");
/* If we're going to be a SNMP master agent... */
if (!agentx_subagent)
init_master_agent(); /* Listen on default port (161). */
/* Your main loop here... */
while (whatever) {
/* if you use select(), see snmp_api(3) */
/* --- OR --- */
agent_check_and_process(0); /* 0 == don't block */
}
/* At shutdown time: */
snmp_shutdown("yourappname");
}
Then:
$(CC) ... `net-snmp-config --agent-libs`
DESCRIPTION
Our goal is to create a easy to use interface to the Net-SNMP package
such that you can take code that you have written that has been
designed to be a Net-SNMP MIB module and embed it into an external
application where you can either chose to be a SNMP master agent or an
AgentX sub-agent using the same MIB module code. Our suggestion is
that you use our (or another) SNMP agent as the AgentX master agent and
chose to become an AgentX subagent which then attaches to the master.
The Net-SNMP package provides a pair of libraries that enables easy
embedding of an SNMP or AgentX agent into an external software package.
AgentX is an extensible protocol designed to allow multiple SNMP sub-
agents all run on one machine under a single SNMP master agent. It is
defined in RFC 2741.
You will need to perform a few tasks in order to accomplish this. First
off, you will need to initialize both the SNMP library and the SNMP
agent library. As indicated above, this is done slightly differently
depending on whether or not you are going to perform as a master agent
or an AgentX sub-agent.
CONFIGURATION
If you intend to operate as an AgentX sub-agent, you will have to con-
figured the Net-SNMP package with agentx support (which is turned on by
default, so just don't turn it off)
Additionally, you will need to link against the Net-SNMP libraries (use
the output of "net-snmp-config --agent-libs" to get a library list) and
call subagent_pre_init() as indicated above.
COMPILING
In order to make use of any of the above API, you will need to link
against at least the four libraries listed above.
FUNCTIONS
where to find out more information on them. It is certainly not a com-
plete list of what is available within all the Net-SNMP libraries.
snmp_enable_stderrlog()
Logs error output from the SNMP agent to the standard error
stream.
netsnmp_ds_set_boolean()
Please see the default_store(3) manual page for more information
about this API.
init_agent(char *name)
Initializes the embedded agent. This should be called before
the init_snmp() call. name is used to dictate what .conf file
to read when init_snmp() is called later.
init_snmp(char *name)
Initializes the SNMP library. Note that one of the things this
will do will be to read configuration files in an effort to con-
figure your application. It will attempt to read the configura-
tion files named by the name string that you passed in. It can
be used to configure access control, for instance. Please see
the netsnmp_config_api(3), snmp_config(5), and snmpd.conf(5)
manual pages for further details on this subject.
init_master_agent(void)
Initializes the master agent and causes it to listen for SNMP
requests on its default UDP port of 161.
agent_check_and_process(int block)
This checks for packets arriving on the SNMP port and processes
them if some are found. If block is non-zero, the function call
will block until a packet arrives or an alarm must be run (see
snmp_alarm(3)). The return value from this function is a posi-
tive integer if packets were processed, zero if an alarm
occurred and -1 if an error occured.
snmp_shutdown(char *name);
This shuts down the agent, saving any needed persistent storage,
etc.
ATTRIBUTES
See attributes(7) for descriptions of the following attributes:
+---------------+---------------------------------+
|ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+---------------+---------------------------------+
|Availability | system/management/snmp/net-snmp |
+---------------+---------------------------------+
|Stability | Volatile |
+---------------+---------------------------------+
SEE ALSO
http://www.net-snmp.org/tutorial-5/toolkit/ select(2), snmp_api(3),
default_store(3), snmp_alarm(3), netsnmp_config_api(3), snmp_config(5),
snmpd.conf(5)
NOTES
Source code for open source software components in Oracle Solaris can
be found at https://www.oracle.com/downloads/opensource/solaris-source-
code-downloads.html.
This software was built from source available at
https://github.com/oracle/solaris-userland. The original community
source was downloaded from https://sourceforge.net/projects/net-
snmp/files/net-snmp/5.8/net-snmp-5.8.tar.gz.
Further information about this software can be found on the open source
community website at http://www.net-snmp.org/.
V5.8 13 Aug 2010 NETSNMP_AGENT_API(3)