ACE/ASNMP/asnmp/transaction.cpp

   1
   2 //=============================================================================
   3 /**
   4  *  @file    transaction.cpp
   5  *
   6  *  implements blocking SNMPv1 API using a simple state machine
   7  * transactions over UDP/IP networks
   8  *
   9  *  @author Michael R MacFaden  mrm@cisco.com - remove v2c
  10  *  @author async
  11  *  @author rework for ACE
  12  */
  13 //=============================================================================
  14
  15
  16 #include "ace/Reactor.h"
  17 #include "asnmp/transaction.h"
  18 #include "ace/OS_NS_string.h"
  19
  20 // pre: pdu, target report  valid() == 1
  21 // post: pdu sent out over the wire
  22 inline void reset_receive_buffer(iovec& io)
  23 {
  24   io.iov_base = 0;
  25   io.iov_len = 0;
  26 }
  27
  28 transaction::transaction(const Pdu& pdu, const UdpTarget& target,
  29                          ACE_SOCK_Dgram& io):
  30                          result_(0),
  31                          wp_(pdu,target), params_(target), session_(io)
  32 {
  33   // last step, convert address (get ride of this once we have merged address
  34   UdpAddress udp;
  35   target.get_address(udp);
  36   // via string conversion "dotted-quad:port"
  37   ACE_INET_Addr tmp(udp);
  38   addr_ = tmp;
  39   reset_receive_buffer(receive_iovec_);
  40 }
  41
  42 transaction::~transaction()
  43 {
  44   ACE_Reactor::instance()->remove_handler(this, READ_MASK | DONT_CALL);
  45   ACE_Reactor::instance()->cancel_timer(this);
  46
  47   delete [] (char *) receive_iovec_.iov_base;
  48 }
  49
  50 // implement state machine, send, wait (timeout/results) return
  51 int transaction::run()
  52 {
  53   int rc, done = 0;
  54   int retry_counter = 0;
  55   ACE_Time_Value to(params_.get_timeout(), 0); // seconds
  56   ACE_Reactor *reactor = ACE_Reactor::instance ();
  57
  58   // 1. register io port for read access
  59   if (reactor->register_handler(session_.get_handle(), this,
  60                                 ACE_Event_Handler::READ_MASK) == -1)
  61     return SNMP_CLASS_INTERNAL_ERROR;
  62
  63   // register a time handler and a socket with this
  64
  65   while (!done) {
  66     if ((rc = this->send()) < 0)      // send pkt to agent
  67         return rc;
  68     else {
  69       if (retry_counter++ > params_.get_retry())
  70         return SNMP_CLASS_TIMEOUT;
  71     }
  72
  73     // 2. wait for events (timeout, returned msg)
  74     if (( rc = reactor->handle_events (to)) == 1) // one handler registered
  75       return 0;
  76     else {
  77       if (rc == 0) {
  78          to.set(params_.get_timeout(), 0);
  79       }
  80       else
  81         return SNMP_CLASS_INTERNAL_ERROR;
  82     }
  83    }
  84   return SNMP_CLASS_INTERNAL_ERROR;
  85 }
  86
  87 // implement state machine, send, wait (timeout/results) return
  88 int transaction::run(transaction_result * r)
  89 {
  90     result_ = r;
  91     int rc;
  92
  93     // 1. register io port for read access
  94     ACE_Reactor * reactor = ACE_Reactor::instance();
  95     if (reactor->register_handler(session_.get_handle(),
  96                                   this,
  97                                   READ_MASK) == -1)
  98         return SNMP_CLASS_INTERNAL_ERROR;
  99
 100     retry_counter_ = 0;
 101
 102     // register a time handler and a socket with this
 103     ACE_Time_Value to (params_.get_timeout());
 104     if (reactor->schedule_timer(this, 0, to, to) == -1)
 105         return SNMP_CLASS_INTERNAL_ERROR;
 106
 107     if ((rc = this->send()) < 0)      // send pkt to agent
 108         return rc;
 109     return 0;
 110 }
 111
 112 // got back response from SNMPv1 agent - process it
 113 int transaction::handle_input (ACE_HANDLE)
 114 {
 115   // OS allocates iovec_.iov_base ptr and len
 116   delete [] (char*) receive_iovec_.iov_base;
 117   reset_receive_buffer(receive_iovec_);
 118   int rc = session_.recv(&receive_iovec_, receive_addr_, 0);
 119   if (rc == -1)
 120     {
 121       delete [] (char*) receive_iovec_.iov_base;
 122       reset_receive_buffer(receive_iovec_);
 123       if (result_)
 124         result_->result(this, SNMP_CLASS_RESOURCE_UNAVAIL);
 125       return SNMP_CLASS_RESOURCE_UNAVAIL;
 126     }
 127   if (result_)
 128     result_->result(this, rc);
 129
 130   return 0;
 131 }
 132
 133 int transaction::handle_timeout(const ACE_Time_Value &,
 134                                 const void *)
 135 {
 136     if (this->send() < 0)      // send pkt to agent
 137         result_->result(this, 0);
 138     else
 139         if (retry_counter_++ > params_.get_retry())
 140             result_->result(this, SNMP_CLASS_TIMEOUT);
 141
 142     return 0;
 143 }
 144
 145
 146 const ACE_INET_Addr& transaction::get_from_addr() const
 147 {
 148   return receive_addr_;
 149 }
 150
 151
 152 // return pdu to caller
 153 int transaction::result(Pdu& pdu, char *comm_str, ACE_INET_Addr *from)
 154 {
 155   // TODO: check to see the sender matches the receiver address..
 156
 157   // remove any vbs existing in this pdu
 158   pdu.delete_all_vbs();
 159
 160  // any data to return?
 161  if (receive_iovec_.iov_len == 0)
 162    return -1;
 163
 164  wpdu tmp(receive_iovec_);
 165
 166  snmp_version ver;
 167
 168  // return comm str and from address of incomming pdu if requested
 169  int rc = tmp.get_pdu(pdu, ver);
 170  if (comm_str)
 171    ACE_OS::strcpy(comm_str, (char *)tmp.get_community());
 172  if (from)
 173   *from = receive_addr_;
 174  return rc;
 175 }
 176
 177 transaction::transaction(ACE_SOCK_Dgram& io)
 178 : result_(0), session_(io)
 179 {
 180   reset_receive_buffer(receive_iovec_);
 181 }
 182
 183
 184 int transaction::send()
 185 {
 186   iovec io = wp_.get_buffer();
 187   if (io.iov_len == 0) {
 188     // NO DATA ?
 189     return -1;
 190   }
 191   ssize_t rc = session_.send (io.iov_base, io.iov_len, addr_ , 0);
 192   return rc;
 193 }
 194
 195 transaction_result::~transaction_result() {}
 196
 197 ACE_HANDLE
 198 transaction::get_handle () const
 199 {
 200   return session_.get_handle ();
 201 }