Class: NETSNMP::PDU

Inherits:
Object
  • Object
show all
Defined in:
lib/netsnmp/pdu.rb

Overview

Abstracts the PDU base structure into a ruby object. It gives access to its varbinds.

Direct Known Subclasses

ScopedPDU

Constant Summary collapse

MAXREQUESTID = 
2147483647

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(type:, headers:, request_id: nil, error_status: 0, error_index: 0, varbinds: []) ⇒ PDU

Returns a new instance of PDU.



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# File 'lib/netsnmp/pdu.rb', line 66

def initialize(type:, headers:,
               request_id: nil,
               error_status: 0,
               error_index: 0,
               varbinds: [])
  @version, @community = headers
  @version = @version.to_i
  @error_status = error_status
  @error_index  = error_index
  @type = type
  @varbinds = []
  varbinds.each do |varbind|
    add_varbind(varbind)
  end
  @request_id = request_id || SecureRandom.random_number(MAXREQUESTID)
  check_error_status(@error_status)
end

Instance Attribute Details

#community ⇒ Object (readonly)

Returns the value of attribute community.



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# File 'lib/netsnmp/pdu.rb', line 64

def community
  @community
end

#request_id ⇒ Object (readonly)

Returns the value of attribute request_id.



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# File 'lib/netsnmp/pdu.rb', line 64

def request_id
  @request_id
end

#type ⇒ Object (readonly)

Returns the value of attribute type.



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# File 'lib/netsnmp/pdu.rb', line 62

def type
  @type
end

#varbinds ⇒ Object (readonly)

Returns the value of attribute varbinds.



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# File 'lib/netsnmp/pdu.rb', line 62

def varbinds
  @varbinds
end

#version ⇒ Object (readonly)

Returns the value of attribute version.



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# File 'lib/netsnmp/pdu.rb', line 64

def version
  @version
end

Class Method Details

.build(type, **args) ⇒ Object

factory method that abstracts initialization of the pdu types that the library supports.

Parameters:

  • type (Symbol) —

    the type of pdu structure to build



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# File 'lib/netsnmp/pdu.rb', line 47

def build(type, **args)
  typ = case type
        when :get       then 0
        when :getnext   then 1
        #          when :getbulk   then 5
        when :set       then 3
        when :inform    then 6
        when :trap      then 7
        when :response  then 2
        else raise Error, "#{type} is not supported as type"
        end
  new(args.merge(type: typ))
end

.decode(der) ⇒ Object 



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# File 'lib/netsnmp/pdu.rb', line 10

def decode(der)
  asn_tree = case der
             when String
               OpenSSL::ASN1.decode(der)
             when OpenSSL::ASN1::ASN1Data
               der
             else
               raise "#{der}: unexpected data"
             end

  *headers, request = asn_tree.value

  version, community = headers.map(&:value)

  type = request.tag

  *request_headers, varbinds = request.value

  request_id, error_status, error_index = request_headers.map(&:value).map(&:to_i)

  varbs = varbinds.value.map do |varbind|
    oid_asn, val_asn = varbind.value
    oid = oid_asn.value
    { oid: oid, value: val_asn }
  end

  new(type: type, headers: [version, community],
      error_status: error_status,
      error_index: error_index,
      request_id: request_id,
      varbinds: varbs)
end

Instance Method Details

#add_varbind(oid:, **options) ⇒ Object Also known as: <<

Adds a request varbind to the pdu

Parameters:

  • oid (OID) —

    a valid oid

  • options (Hash) —

    additional request varbind options

Options Hash (**options):

  • :value (Object) —

    the value for the oid



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# File 'lib/netsnmp/pdu.rb', line 93

def add_varbind(oid:, **options)
  @varbinds << Varbind.new(oid, **options)
end

#to_asn ⇒ Object 



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# File 'lib/netsnmp/pdu.rb', line 98

def to_asn
  request_id_asn = OpenSSL::ASN1::Integer.new(@request_id)
  error_asn = OpenSSL::ASN1::Integer.new(@error_status)
  error_index_asn = OpenSSL::ASN1::Integer.new(@error_index)

  varbind_asns = OpenSSL::ASN1::Sequence.new(@varbinds.map(&:to_asn))

  request_asn = OpenSSL::ASN1::ASN1Data.new([request_id_asn,
                                             error_asn, error_index_asn,
                                             varbind_asns], @type,
                                            :CONTEXT_SPECIFIC)

  OpenSSL::ASN1::Sequence.new([*encode_headers_asn, request_asn])
end

#to_der ⇒ Object 



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# File 'lib/netsnmp/pdu.rb', line 84

def to_der
  to_asn.to_der
end