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// implement a prototype SNMP Agent using ASNMP and ACE
#include <ace/Reactor.h>
#include <ace/SOCK_Dgram.h>
#include <ace/INET_Addr.h>
#include <ace/Signal.h>
#include "agent_impl.h"
agent_impl::agent_impl(unsigned short port, const char *rd, const char *wr) :
sagent(port)
{
ACE_TRACE("agent_impl::agent_impl");
tgt_.set_read_community(rd);
tgt_.set_write_community(wr);
agent_clock_.start();
}
agent_impl::~agent_impl()
{
ACE_TRACE("agent_impl::~agent_impl");
}
// callback : have received a Pdu from the target host with given read comm str
// this is really simplistic, but gives the general idea
int agent_impl::handle_get( Pdu &pdu, UdpTarget &target)
{
ACE_TRACE("agent_impl::handle_get");
OctetStr mgr_rd_str, agent_rd_str;
target.get_read_community(mgr_rd_str); // requster's read community string
tgt_.get_read_community(agent_rd_str); // this agent's read community string
// 1. verify we have a valid read string else drop pdu (no response to caller)
if (mgr_rd_str != agent_rd_str) {
ACE_DEBUG((LM_DEBUG, "agent_impl::handle_get: invalid read community recvd\n"));
return 0;
}
// 2. iterate over each varbind in the pdu, filling providing responses
int fdone = 0;
for (int i = 0; (i < pdu.get_vb_count()) && !fdone; i++) {
Vb vb;
pdu.get_vb(vb, i);
if (get_response(vb)) { // set a value for the oid if we can else
set_error_status(&pdu, SNMP_ERROR_NO_SUCH_NAME); // these ought to be member
set_error_index(&pdu, i); // functions but are not yet...
fdone++; // trigger flag to exit loop early
}
else // failed, return noSuch error
pdu.set_vb(vb, i);
}
// 3. lastly, return the pkt to the caller
return respond(pdu, target);
}
// this routine makes up the brains of the agent
// it knows only the MIB II system group set of variables for a get operation
int agent_impl::get_response(Vb& vb)
{
// these objects represent the MIB II system group per RFC 1213
static Oid sysDescr("1.3.6.1.2.1.1.1.0"),
sysObjectID("1.3.6.1.2.1.1.2.0"), sysUpTime("1.3.6.1.2.1.1.3.0"),
sysContact("1.3.6.1.2.1.1.4.0"), sysName("1.3.6.1.2.1.1.5.0"),
sysLocation("1.3.6.1.2.1.1.6.0"), sysServices("1.3.6.1.2.1.1.7.0");
Oid oid;
vb.get_oid(oid);
if (oid == sysDescr) {
OctetStr desc("ASNMP Prototype Agent 1.0");
vb.set_value(desc);
}
else if (oid == sysObjectID) { // the IANA gives assigns Enterprise Numbers
// see ftp://ftp.isi.edu/in-notes/iana/assignments/enterprise-numbers
// for the official list of enterprise numbers. Then under this tree
// assign a unique subtree to identify this agent
Oid id("1.3.6.1.4.1.2533.9.1");
vb.set_value(id);
}
else if (oid == sysUpTime) {
ACE_Time_Value tv;
agent_clock_.elapsed_time (tv);
TimeTicks tt(tv.msec());
vb.set_value(tt);
}
else if (oid == sysContact) {
OctetStr contact("mrm@acm.org");
vb.set_value(contact);
}
else if (oid == sysName) {
OctetStr fqdn("foo.org"); // extract this from the gethostbyname() TODO
vb.set_value(fqdn);
}
else if (oid == sysLocation) {
OctetStr loc("");
vb.set_value(loc);
}
else if (oid == sysServices) {
SnmpInt32 svcs(72);
vb.set_value(svcs);
}
else
return 1; // noSuchName
return 0;
}
int agent_impl::handle_get_next( Pdu &, UdpTarget &)
{
ACE_TRACE("agent_impl::handle_get_next -NI");
return 0;
}
int agent_impl::handle_set( Pdu &, UdpTarget &)
{
ACE_TRACE("agent_impl::handle_set -NI");
return 0;
}
// stuff used by process_requests
// called when SIGINT
static sig_atomic_t finished = 0;
extern "C" void
sig_handler (int)
{
ACE_TRACE("::sig_handler");
finished = 1;
}
int agent_impl::process_requests()
{
ACE_TRACE("agent_impl::process_requests");
ACE_Reactor reactor;
ACE_Sig_Action sa ((ACE_SignalHandler) sig_handler, SIGINT);
ACE_UNUSED_ARG (sa);
// Read data from other side.
if (reactor.register_handler (this, ACE_Event_Handler::READ_MASK) == -1)
ACE_ERROR_RETURN ((LM_ERROR, "ACE_Reactor::register_handler"), -1);
// TODO: register signal handler to shut down gracefully here
while (!finished)
{
reactor.handle_events ();
ACE_DEBUG ((LM_DEBUG, "return from handle events\n"));
}
ACE_DEBUG ((LM_DEBUG, "return from handle events - normal shut down\n"));
return 0;
}
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