ACE/ASNMP/agent/agent_impl.cpp

   1 // implement a prototype SNMP Agent using ASNMP and ACE
   2
   3 #include <ace/Reactor.h>
   4 #include <ace/SOCK_Dgram.h>
   5 #include <ace/INET_Addr.h>
   6 #include <ace/Signal.h>
   7
   8 #include "agent_impl.h"
   9
  10 agent_impl::agent_impl(unsigned short port, const char *rd, const char *wr) :
  11 sagent(port)
  12 {
  13   ACE_TRACE("agent_impl::agent_impl");
  14   tgt_.set_read_community(rd);
  15   tgt_.set_write_community(wr);
  16   agent_clock_.start();
  17 }
  18
  19 agent_impl::~agent_impl()
  20 {
  21    ACE_TRACE("agent_impl::~agent_impl");
  22 }
  23
  24 // callback : have received a Pdu from the target host with given read comm str
  25 // this is really simplistic, but gives the general idea
  26 int agent_impl::handle_get( Pdu &pdu, UdpTarget &target)
  27 {
  28   ACE_TRACE("agent_impl::handle_get");
  29   OctetStr mgr_rd_str, agent_rd_str;
  30   target.get_read_community(mgr_rd_str); // requster's read community string
  31   tgt_.get_read_community(agent_rd_str); // this agent's read community string
  32
  33   //  1. verify we have a valid read string else drop pdu (no response to caller)
  34   if (mgr_rd_str != agent_rd_str) {
  35      ACE_DEBUG((LM_DEBUG, "agent_impl::handle_get: invalid read community recvd\n"));
  36      return 0;
  37   }
  38
  39   // 2. iterate over each varbind in the pdu, filling providing responses
  40   int fdone = 0;
  41   for (int i = 0; (i < pdu.get_vb_count()) && !fdone; i++) {
  42     Vb vb;
  43     pdu.get_vb(vb, i);
  44     if (get_response(vb)) { // set a value for the oid if we can else
  45       set_error_status(&pdu, SNMP_ERROR_NO_SUCH_NAME); // these ought to be member
  46       set_error_index(&pdu, i); // functions but are not yet...
  47       fdone++; // trigger flag to exit loop early
  48     }
  49     else // failed, return noSuch error
  50       pdu.set_vb(vb, i);
  51   }
  52
  53   // 3. lastly, return the pkt to the caller
  54   return respond(pdu, target);
  55 }
  56
  57 // this routine makes up the brains of the agent
  58 // it knows only the MIB II system group set of variables for a get operation
  59 int agent_impl::get_response(Vb& vb)
  60 {
  61   // these objects represent the MIB II system group per RFC 1213
  62    static Oid sysDescr("1.3.6.1.2.1.1.1.0"),
  63    sysObjectID("1.3.6.1.2.1.1.2.0"), sysUpTime("1.3.6.1.2.1.1.3.0"),
  64    sysContact("1.3.6.1.2.1.1.4.0"), sysName("1.3.6.1.2.1.1.5.0"),
  65    sysLocation("1.3.6.1.2.1.1.6.0"), sysServices("1.3.6.1.2.1.1.7.0");
  66
  67   Oid oid;
  68   vb.get_oid(oid);
  69   if (oid == sysDescr) {
  70     OctetStr desc("ASNMP Prototype Agent 1.0");
  71     vb.set_value(desc);
  72   }
  73   else if (oid == sysObjectID) { // the IANA gives assigns Enterprise Numbers
  74     // see ftp://ftp.isi.edu/in-notes/iana/assignments/enterprise-numbers
  75     // for the official list of enterprise numbers. Then under this tree
  76     // assign a unique subtree to identify this agent
  77     Oid id("1.3.6.1.4.1.2533.9.1");
  78     vb.set_value(id);
  79   }
  80   else if (oid == sysUpTime) {
  81     ACE_Time_Value tv;
  82     agent_clock_.elapsed_time (tv);
  83     TimeTicks tt(tv.msec());
  84     vb.set_value(tt);
  85   }
  86   else if (oid == sysContact) {
  87     OctetStr contact("mrm@acm.org");
  88     vb.set_value(contact);
  89   }
  90   else if (oid == sysName) {
  91     OctetStr fqdn("foo.org"); // extract this from the gethostbyname() TODO
  92     vb.set_value(fqdn);
  93   }
  94   else if (oid == sysLocation) {
  95     OctetStr loc("");
  96     vb.set_value(loc);
  97   }
  98   else if (oid == sysServices) {
  99     SnmpInt32 svcs(72);
 100     vb.set_value(svcs);
 101   }
 102   else
 103     return 1; // noSuchName
 104
 105   return 0;
 106 }
 107
 108 int agent_impl::handle_get_next( Pdu &, UdpTarget &)
 109 {
 110    ACE_TRACE("agent_impl::handle_get_next -NI");
 111   return 0;
 112 }
 113
 114 int agent_impl::handle_set( Pdu &, UdpTarget &)
 115 {
 116  ACE_TRACE("agent_impl::handle_set -NI");
 117  return 0;
 118 }
 119
 120 // stuff used by process_requests
 121
 122 // called when SIGINT
 123 static sig_atomic_t finished = 0;
 124
 125 extern "C" void
 126 sig_handler (int)
 127 {
 128   ACE_TRACE("::sig_handler");
 129   finished = 1;
 130 }
 131
 132 int agent_impl::process_requests()
 133 {
 134   ACE_TRACE("agent_impl::process_requests");
 135   ACE_Reactor reactor;
 136
 137   ACE_Sig_Action sa ((ACE_SignalHandler) sig_handler, SIGINT);
 138   ACE_UNUSED_ARG (sa);
 139
 140   // Read data from other side.
 141   if (reactor.register_handler (this, ACE_Event_Handler::READ_MASK) == -1)
 142     ACE_ERROR_RETURN ((LM_ERROR, "ACE_Reactor::register_handler"), -1);
 143
 144   // TODO: register signal handler to shut down gracefully here
 145
 146   while (!finished)
 147     {
 148       reactor.handle_events ();
 149       ACE_DEBUG ((LM_DEBUG, "return from handle events\n"));
 150     }
 151
 152   ACE_DEBUG ((LM_DEBUG, "return from handle events - normal shut down\n"));
 153   return 0;
 154 }