Setup a basic project and program driver

.gitignore

@@ -0,0 +1,3 @@
+/scratch/
+/jasn1-*.gem
+.DS_Store

LICENSE

@@ -0,0 +1,7 @@
+Copyright (c) Nick Chambers <uplime@spookyinternet.com>
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

README.md

@@ -0,0 +1,3 @@
+# Jasn1
+
+Display an X.509 DER-encoded certificate as a JSON string.

bin/jasn1

@@ -0,0 +1,18 @@
+#!/usr/bin/env ruby
+
+if $PROGRAM_NAME.start_with?("bin/")
+  $LOAD_PATH.unshift(File.expand_path("./lib", "."))
+end
+
+require "jasn1"
+
+opts = Jasn1::Options::Options.new do |opt|
+  opt.arg(key: "format", values: ["openssl", "verbose", "basic"])
+  opt.arg(key: "critical", default: false)
+end
+
+opts.args.each do |filename|
+  contents = File.open(filename) do |file|
+    file.read
+  end
+end

jasn1.gemspec

@@ -0,0 +1,9 @@
+Gem::Specification.new do |spec|
+  spec.name = "jasn1"
+  spec.version = "0.0.1"
+  spec.summary = "Display an X.509 DER-encoded certificate as a JSON string."
+  spec.authors = ["uplime"]
+  spec.executables = ["jasn1"]
+  spec.files = ["lib/jasn1.rb"]
+  spec.license = "MIT"
+end

lib/jasn1.rb

@@ -0,0 +1,2 @@
+require "jasn1/asn1"
+require "jasn1/options"

lib/jasn1/options.rb

@@ -0,0 +1,138 @@
+module Jasn1
+  module Options
+    class NoKeyError < StandardError
+    end
+
+    class AmbiguousTypeError < StandardError
+    end
+
+    class TypeValueMismatchError < StandardError
+    end
+
+    class DefaultTypeMismatchError < StandardError
+    end
+
+    class UnrecognizedFlagError < StandardError
+    end
+
+    class NoValueError < StandardError
+    end
+
+    class UnsupportedValueError < StandardError
+    end
+
+    class Option
+      attr_reader :type, :values
+      attr_accessor :value
+
+      def initialize(type, values, default)
+        @type = type
+        @values = values
+        @value = default
+      end
+    end
+
+    class OptionsManager
+      attr_reader :opts
+
+      def initialize
+        @opts = { }
+        @strict = false
+      end
+
+      def arg(key: "", type: nil, values: [], default: nil)
+        if key.empty?
+          raise NoKeyError
+        end
+
+        if default.nil? and not values.empty?
+          default = values.first
+        end
+
+        if type.nil?
+          if not default.nil?
+            type = default.class
+          elsif not values.empty?
+            type = values.first.class
+          else
+            raise AmbiguousTypeError
+          end
+        else
+          bad_values = values.filter do |value|
+            not value.is_a?(type)
+          end
+
+          if not bad_values.empty?
+            raise TypeValueMismatchError
+          elsif not default.nil? and not default.is_a?(type)
+            raise DefaultTypeMismatchError
+          end
+        end
+
+        @opts[key] = Option.new(type, values, default)
+      end
+
+      def boolean?(key)
+        [TrueClass, FalseClass].include? @opts[key].type
+      end
+    end
+
+    class Options
+      attr_reader :args
+
+      def initialize(args=ARGV)
+        if not block_given?
+          return
+        end
+
+        scanning = true
+        @args = args.clone
+        @mgr = OptionsManager.new
+        yield @mgr
+
+        while not @args.empty? and scanning
+          if @args.first == "--"
+            @args.shift
+            scanning = false
+          elsif @args.first[0] != "-"
+            scanning = false
+          end
+
+          if scanning
+            opt = @args.shift[1..]
+            flip = false
+
+            if opt.start_with?("no-")
+              opt = opt[3..]
+              flip = true
+            end
+
+            key, val = opt.split("=", 2)
+
+            if not @mgr.opts.key? key
+              raise UnrecognizedFlagError
+            end
+
+            if @mgr.boolean? key
+              @mgr.opts[key].value = if val.nil?
+                !flip
+              else
+                somehow_convert_to_boolean val
+              end
+            elsif val.nil?
+              raise NoValueError
+            elsif not @mgr.opts[key].values.include? val
+              raise UnsupportedValueError
+            else
+              @mgr.opts[key].value = @mgr.opts[key].type.new(val)
+            end
+          end
+        end
+      end
+
+      def [](key)
+        @mgr.opts[idx].value
+      end
+    end
+  end
+end