268 lines
6.3 KiB
Ruby
268 lines
6.3 KiB
Ruby
# :stopdoc:
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module Net
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class SNMP
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VERSION = '0.2'
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AsnSyntax = Net::BER.compile_syntax({
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:application => {
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:primitive => {
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1 => :integer, # Counter32, (RFC2578 sec 2)
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2 => :integer, # Gauge32 or Unsigned32, (RFC2578 sec 2)
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3 => :integer # TimeTicks32, (RFC2578 sec 2)
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},
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:constructed => {
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}
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},
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:context_specific => {
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:primitive => {
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},
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:constructed => {
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0 => :array, # GetRequest PDU (RFC1157 pgh 4.1.2)
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1 => :array, # GetNextRequest PDU (RFC1157 pgh 4.1.3)
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2 => :array # GetResponse PDU (RFC1157 pgh 4.1.4)
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}
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}
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})
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# SNMP 32-bit counter.
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# Defined in RFC1155 (Structure of Mangement Information), section 6.
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# A 32-bit counter is an ASN.1 application [1] implicit unsigned integer
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# with a range from 0 to 2^^32 - 1.
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class Counter32
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def initialize value
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@value = value
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end
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def to_ber
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@value.to_ber_application(1)
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end
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end
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# SNMP 32-bit gauge.
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# Defined in RFC1155 (Structure of Mangement Information), section 6.
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# A 32-bit counter is an ASN.1 application [2] implicit unsigned integer.
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# This is also indistinguishable from Unsigned32. (Need to alias them.)
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class Gauge32
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def initialize value
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@value = value
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end
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def to_ber
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@value.to_ber_application(2)
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end
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end
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# SNMP 32-bit timer-ticks.
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# Defined in RFC1155 (Structure of Mangement Information), section 6.
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# A 32-bit counter is an ASN.1 application [3] implicit unsigned integer.
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class TimeTicks32
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def initialize value
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@value = value
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end
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def to_ber
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@value.to_ber_application(3)
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end
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end
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end
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class SnmpPdu
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class Error < StandardError; end
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PduTypes = [
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:get_request,
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:get_next_request,
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:get_response,
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:set_request,
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:trap
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]
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ErrorStatusCodes = { # Per RFC1157, pgh 4.1.1
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0 => "noError",
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1 => "tooBig",
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2 => "noSuchName",
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3 => "badValue",
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4 => "readOnly",
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5 => "genErr"
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}
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class << self
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def parse ber_object
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n = new
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n.send :parse, ber_object
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n
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end
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end
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attr_reader :version, :community, :pdu_type, :variables, :error_status
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attr_accessor :request_id, :error_index
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def initialize args={}
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@version = args[:version] || 0
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@community = args[:community] || "public"
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@pdu_type = args[:pdu_type] # leave nil unless specified; there's no reasonable default value.
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@error_status = args[:error_status] || 0
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@error_index = args[:error_index] || 0
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@variables = args[:variables] || []
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end
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#--
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def parse ber_object
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begin
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parse_ber_object ber_object
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rescue Error
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# Pass through any SnmpPdu::Error instances
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raise $!
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rescue
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# Wrap any basic parsing error so it becomes a PDU-format error
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raise Error.new( "snmp-pdu format error" )
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end
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end
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private :parse
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def parse_ber_object ber_object
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send :version=, ber_object[0].to_i
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send :community=, ber_object[1].to_s
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data = ber_object[2]
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case (app_tag = data.ber_identifier & 31)
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when 0
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send :pdu_type=, :get_request
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parse_get_request data
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when 1
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send :pdu_type=, :get_next_request
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# This PDU is identical to get-request except for the type.
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parse_get_request data
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when 2
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send :pdu_type=, :get_response
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# This PDU is identical to get-request except for the type,
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# the error_status and error_index values are meaningful,
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# and the fact that the variable bindings will be non-null.
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parse_get_response data
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else
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raise Error.new( "unknown snmp-pdu type: #{app_tag}" )
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end
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end
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private :parse_ber_object
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#--
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# Defined in RFC1157, pgh 4.1.2.
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def parse_get_request data
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send :request_id=, data[0].to_i
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# data[1] is error_status, always zero.
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# data[2] is error_index, always zero.
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send :error_status=, 0
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send :error_index=, 0
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data[3].each {|n,v|
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# A variable-binding, of which there may be several,
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# consists of an OID and a BER null.
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# We're ignoring the null, we might want to verify it instead.
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unless v.is_a?(Net::BER::BerIdentifiedNull)
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raise Error.new(" invalid variable-binding in get-request" )
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end
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add_variable_binding n, nil
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}
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end
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private :parse_get_request
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#--
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# Defined in RFC1157, pgh 4.1.4
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def parse_get_response data
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send :request_id=, data[0].to_i
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send :error_status=, data[1].to_i
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send :error_index=, data[2].to_i
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data[3].each {|n,v|
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# A variable-binding, of which there may be several,
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# consists of an OID and a BER null.
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# We're ignoring the null, we might want to verify it instead.
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add_variable_binding n, v
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}
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end
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private :parse_get_response
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def version= ver
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unless [0,2].include?(ver)
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raise Error.new("unknown snmp-version: #{ver}")
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end
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@version = ver
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end
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def pdu_type= t
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unless PduTypes.include?(t)
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raise Error.new("unknown pdu-type: #{t}")
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end
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@pdu_type = t
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end
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def error_status= es
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unless ErrorStatusCodes.has_key?(es)
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raise Error.new("unknown error-status: #{es}")
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end
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@error_status = es
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end
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def community= c
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@community = c.to_s
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end
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#--
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# Syntactic sugar
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def add_variable_binding name, value=nil
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@variables ||= []
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@variables << [name, value]
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end
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def to_ber_string
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[
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version.to_ber,
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community.to_ber,
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pdu_to_ber_string
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].to_ber_sequence
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end
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#--
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# Helper method that returns a PDU payload in BER form,
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# depending on the PDU type.
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def pdu_to_ber_string
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case pdu_type
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when :get_request
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[
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request_id.to_ber,
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error_status.to_ber,
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error_index.to_ber,
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[
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@variables.map {|n,v|
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[n.to_ber_oid, Net::BER::BerIdentifiedNull.new.to_ber].to_ber_sequence
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}
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].to_ber_sequence
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].to_ber_contextspecific(0)
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when :get_next_request
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[
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request_id.to_ber,
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error_status.to_ber,
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error_index.to_ber,
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[
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@variables.map {|n,v|
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[n.to_ber_oid, Net::BER::BerIdentifiedNull.new.to_ber].to_ber_sequence
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}
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].to_ber_sequence
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].to_ber_contextspecific(1)
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when :get_response
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[
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request_id.to_ber,
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error_status.to_ber,
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error_index.to_ber,
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[
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@variables.map {|n,v|
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[n.to_ber_oid, v.to_ber].to_ber_sequence
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}
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].to_ber_sequence
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].to_ber_contextspecific(2)
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else
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raise Error.new( "unknown pdu-type: #{pdu_type}" )
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end
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end
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private :pdu_to_ber_string
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end
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end
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# :startdoc:
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