Class: SNMP4EM::Manager

Inherits:
Object
  • Object
show all
Includes:
SNMPCommonRequests
Defined in:
lib/snmp4em/manager.rb

Overview

Provides access to send and receive SNMP messages via a UDP socket.

Note - The methods for actually sending requests are documented in SNMPCommonRequests and, for those specific to SNMPv2, SNMPv2cRequests.

Constant Summary collapse

MAX_INDEX = 
2**31

Class Attribute Summary collapse

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Methods included from SNMPCommonRequests

#get, #getnext, #set, #walk

Constructor Details

#initialize(args = {}) ⇒ Manager

Creates a new object to communicate with SNMP agents. Optionally pass in the following parameters:

  • host - IP/hostname of remote agent (default: 127.0.0.1)

  • port - UDP port on remote agent (default: 161)

  • community - Community string to use for all operations (default: public)

  • community_ro - Read-only community string to use for read-only operations (default: public)

  • community_rw - Read-write community string to use for read-write operations (default: public)

  • timeout - Number of seconds to wait before a request times out (default: 1)

  • retries - Number of retries before failing (default: 3)

  • version - SNMP version, either :SNMPv1 or :SNMPv2c (default: :SNMPv2c)



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# File 'lib/snmp4em/manager.rb', line 59

def initialize(args = {})
  @host    = args[:host]    || "127.0.0.1"
  @port    = args[:port]    || 161
  @timeout = args[:timeout] || 1
  @retries = args[:retries] || 3
  @version = args[:version] || :SNMPv2c
  @fiber   = args[:fiber]   || false

  self.extend SNMPv2cRequests if @version == :SNMPv2c

  @community_ro = args[:community_ro] || args[:community] || "public"
  @community_rw = args[:community_rw] || args[:community] || "public"
  
  self.class.init_socket
end

Class Attribute Details

.pending_requests ⇒ Object (readonly)

Returns the value of attribute pending_requests.



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# File 'lib/snmp4em/manager.rb', line 20

def pending_requests
  @pending_requests
end

.socket ⇒ Object (readonly)

Returns the value of attribute socket.



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# File 'lib/snmp4em/manager.rb', line 21

def socket
  @socket
end

Instance Attribute Details

#community_ro ⇒ Object (readonly)

Returns the value of attribute community_ro.



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# File 'lib/snmp4em/manager.rb', line 47

def community_ro
  @community_ro
end

#community_rw ⇒ Object (readonly)

Returns the value of attribute community_rw.



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# File 'lib/snmp4em/manager.rb', line 47

def community_rw
  @community_rw
end

#host ⇒ Object (readonly)

Returns the value of attribute host.



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# File 'lib/snmp4em/manager.rb', line 47

def host
  @host
end

#port ⇒ Object (readonly)

Returns the value of attribute port.



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# File 'lib/snmp4em/manager.rb', line 47

def port
  @port
end

#retries ⇒ Object (readonly)

Returns the value of attribute retries.



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# File 'lib/snmp4em/manager.rb', line 47

def retries
  @retries
end

#timeout ⇒ Object (readonly)

Returns the value of attribute timeout.



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# File 'lib/snmp4em/manager.rb', line 47

def timeout
  @timeout
end

#version ⇒ Object (readonly)

Returns the value of attribute version.



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# File 'lib/snmp4em/manager.rb', line 47

def version
  @version
end

Class Method Details

.init_socket ⇒ Object

Initializes the outgoing socket. Checks to see if it’s in an error state, and if so closes and reopens the socket



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# File 'lib/snmp4em/manager.rb', line 24

def init_socket
  if !@socket.nil? && @socket.error?
    @socket.close_connection
    @socket = nil
  end

  @next_index ||= rand(MAX_INDEX)
  @socket ||= EM::open_datagram_socket("0.0.0.0", 0, Handler)
end

.track_request(request) ⇒ Object

Assigns an SNMP ID to an outgoing request so that it can be matched with its incoming response



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# File 'lib/snmp4em/manager.rb', line 35

def track_request(request)
  @pending_requests.delete(request.snmp_id)

  begin
    @next_index = (@next_index + 1) % MAX_INDEX
    request.snmp_id = @next_index
  end while @pending_requests[request.snmp_id]

  @pending_requests[request.snmp_id] = request
end

Instance Method Details

#send_msg(message) ⇒ Object 



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# File 'lib/snmp4em/manager.rb', line 75

def send_msg(message) # @private
  self.class.socket.send_datagram message.encode, @host, @port
end

#wrap_in_fiber(request) ⇒ Object 



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# File 'lib/snmp4em/manager.rb', line 79

def wrap_in_fiber(request) # @private
  require "fiber"

  fiber = Fiber.current

  request.callback do |response|
    fiber.resume response
  end

  request.errback do |error|
    fiber.resume SNMP::RequestTimeout.new(error)
  end

  Fiber.yield
end