setup some parsing infrastructure.

the plan is to have classes fore every packet type and (in a separate
module) the same classes again, but extended by a parsing module such that
each packet can parse itself.

detect first packet headers and parse its size.

can be used e.g. with:
FPG::Parse::Parser.parse( File.open( "spec/fixtures/test.bin.pub" ) )

will create a Signature Packet with size 13

9 files changed, 221 insertions, 90 deletions

diff --git a/lib/fpg/io/radix64.rb b/lib/fpg/io/radix64.rb
index 49102a0..4ecdaf3 100644
--- a/lib/fpg/io/radix64.rb
+++ b/lib/fpg/io/radix64.rb
@@ -1,101 +1,103 @@
 module FPG
-  class Radix64
-    def char_table
-        @char_table ||= "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/".each_byte.collect.to_a
-    end
-    def pad
-        pad_s.unpack("C1!").first
-    end
-    def pad_s
-      "="
-    end
-    def char2six_table
-        @char2six_table ||= Hash[char_table.zip((0..63).to_a)]
-    end
-    def char2six(char)
-        char2six_table[char]
-    end
-    def six2char(six)
-        char_table[six]
-    end
-    def quad2bytes(quad)
-        q = (quad.unpack("C4!").collect { |v| char2six(v) }).to_a
-        [ (q[0]<<2)+(q[1]>>4), ((q[1]<<4)%256)+(q[2]>>2), ((q[2]<<6)%256)+q[3] ]
-    end
-    def padded_quad2bytes(quad)
-        if quad[2] == pad_s then
-            q = quad.unpack("C2!").collect { |v| char2six(v) }
-            [ (q[0]<<2)+(q[1]>>4), ((q[1]<<4)%256)>>4 ]
-        else
-            q = quad.unpack("C3!").collect { |v| char2six(v) }
-            [ (q[0]<<2)+(q[1]>>4),  ((q[1]<<4)%256)+(q[2]>>2), ((q[2]<<6)%256) ]
-        end
-    end
-    def bytes2quad(bytes)
-        [ six2char(bytes[0]>>2),                      six2char(((bytes[0]<<4)%64)+(bytes[1]>>4)),
-          six2char(((bytes[1]<<2)%64)+(bytes[2]>>6)), six2char(bytes[2]%64) ].pack("C4!")
-    end
-    def bytes2padded_quad(bytes)
-        if bytes.length == 1
-            [six2char(bytes[0]>>2), six2char((bytes[0]<<4)%64), pad, pad].pack("C4!")
-        elsif bytes.length == 2
-            [ six2char(bytes[0]>>2), six2char(((bytes[0]<<4)%64)+(bytes[1]>>4)),
-              six2char((bytes[1]<<2)%64), pad].pack("C4!")
-        end
-    end
-    def de_armor( stream )
-      stream.each do |line|
-        line.chop!
-        return if line.length == 0
-        0.step(line.length-1, 4) do |i|
-          quad = line[i..i+3]
-          if quad[3] == pad_s
-            bytes = padded_quad2bytes(quad)
-            if bytes.length == 2 and bytes[1] != 0
-              yield bytes[0]
-              yield bytes[1]
-            elsif bytes[0] != 0
-              yield bytes[0]
+  module Io
+    class Radix64
+      def char_table
+          @char_table ||= "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/".each_byte.collect.to_a
+      end
+      def pad
+          pad_s.unpack("C1!").first
+      end
+      def pad_s
+        "="
+      end
+      def char2six_table
+          @char2six_table ||= Hash[char_table.zip((0..63).to_a)]
+      end
+      def char2six(char)
+          char2six_table[char]
+      end
+      def six2char(six)
+          char_table[six]
+      end
+      def quad2bytes(quad)
+          q = (quad.unpack("C4!").collect { |v| char2six(v) }).to_a
+          [ (q[0]<<2)+(q[1]>>4), ((q[1]<<4)%256)+(q[2]>>2), ((q[2]<<6)%256)+q[3] ]
+      end
+      def padded_quad2bytes(quad)
+          if quad[2] == pad_s then
+              q = quad.unpack("C2!").collect { |v| char2six(v) }
+              [ (q[0]<<2)+(q[1]>>4), ((q[1]<<4)%256)>>4 ]
+          else
+              q = quad.unpack("C3!").collect { |v| char2six(v) }
+              [ (q[0]<<2)+(q[1]>>4),  ((q[1]<<4)%256)+(q[2]>>2), ((q[2]<<6)%256) ]
+          end
+      end
+      def bytes2quad(bytes)
+          [ six2char(bytes[0]>>2),                      six2char(((bytes[0]<<4)%64)+(bytes[1]>>4)),
+            six2char(((bytes[1]<<2)%64)+(bytes[2]>>6)), six2char(bytes[2]%64) ].pack("C4!")
+      end
+      def bytes2padded_quad(bytes)
+          if bytes.length == 1
+              [six2char(bytes[0]>>2), six2char((bytes[0]<<4)%64), pad, pad].pack("C4!")
+          elsif bytes.length == 2
+              [ six2char(bytes[0]>>2), six2char(((bytes[0]<<4)%64)+(bytes[1]>>4)),
+                six2char((bytes[1]<<2)%64), pad].pack("C4!")
+          end
+      end
+      def de_armor( stream )
+        stream.each do |line|
+          line.chop!
+          return if line.length == 0
+          0.step(line.length-1, 4) do |i|
+            quad = line[i..i+3]
+            if quad[3] == pad_s
+              bytes = padded_quad2bytes(quad)
+              if bytes.length == 2 and bytes[1] != 0
+                yield bytes[0]
+                yield bytes[1]
+              elsif bytes[0] != 0
+                yield bytes[0]
+              end
+              return
             end
-            return
+            bytes = quad2bytes(quad)
+            yield bytes[0]
+            yield bytes[1]
+            yield bytes[2]
           end
-          bytes = quad2bytes(quad)
-          yield bytes[0]
-          yield bytes[1]
-          yield bytes[2]
         end
       end
-    end
-    def armor( stream )
-      line_buffer = ""
-      line_length = 0
-      buffer = [0,0,0]
-      buffer_size = 0
-      stream.each_byte do |byte|
-        if buffer_size == 3 then
-          line_buffer << bytes2quad(buffer)
-          line_length += 4
-          buffer_size = 0
+      def armor( stream )
+        line_buffer = ""
+        line_length = 0
+        buffer = [0,0,0]
+        buffer_size = 0
+        stream.each_byte do |byte|
+          if buffer_size == 3 then
+            line_buffer << bytes2quad(buffer)
+            line_length += 4
+            buffer_size = 0
+          end
+          if line_length > 63 then
+            yield line_buffer
+            line_length = 0
+            line_buffer = ""
+          end
+          buffer[buffer_size] = byte
+          buffer_size += 1
         end
-        if line_length > 63 then
-          yield line_buffer
-          line_length = 0
-          line_buffer = ""
+        if buffer_size == 1
+          line_buffer << bytes2padded_quad([buffer[0]])
+        elsif buffer_size == 2
+          line_buffer << bytes2padded_quad([buffer[0],buffer[1]])
         end
-        buffer[buffer_size] = byte
-        buffer_size += 1
+        yield line_buffer
       end
-      if buffer_size == 1
-        line_buffer << bytes2padded_quad([buffer[0]])
-      elsif buffer_size == 2
-        line_buffer << bytes2padded_quad([buffer[0],buffer[1]])
+      def armor_public_key( stream )
+        yield Versioning.public_key_header
+        armor( stream )
+        yield Versioning.public_key_footer
       end
-      yield line_buffer
-    end
-    def armor_public_key( stream )
-      yield Versioning.public_key_header
-      armor( stream )
-      yield Versioning.public_key_footer
     end
   end
 end
diff --git a/lib/fpg/packets/new_packet.rb b/lib/fpg/packets/new_packet.rb
new file mode 100644
index 0000000..417c737
--- /dev/null
+++ b/lib/fpg/packets/new_packet.rb
@@ -0,0 +1,7 @@
+module FPG
+  module Packets
+    class NewPacket
+      attr_accessor :byte_size
+    end
+  end
+end
diff --git a/lib/fpg/packets/signature.rb b/lib/fpg/packets/signature.rb
new file mode 100644
index 0000000..f8f4aef
--- /dev/null
+++ b/lib/fpg/packets/signature.rb
@@ -0,0 +1,6 @@
+module FPG
+  module Packets
+    class Signature < NewPacket
+    end
+  end
+end
diff --git a/lib/fpg/parse/_packet_headers.rb b/lib/fpg/parse/_packet_headers.rb
new file mode 100644
index 0000000..a016a04
--- /dev/null
+++ b/lib/fpg/parse/_packet_headers.rb
@@ -0,0 +1,51 @@
+module FPG
+  module Parse
+    module PacketHeaders
+      def packet_for( byte )
+        case byte
+        when 0
+          raise Error, "a packet tag must not be 0"
+        when 1
+          PublicKeyEncryptedSessionKey.new
+        when 2
+          Signature.new
+        when 3
+          SymmetricKeyEncryptedSession.new
+        when 4
+          OnePassSignature.new
+        when 5
+          SecretKey.new
+        when 6
+          PublicKey.new
+        when 7
+          SecretSubkey.new
+        when 8
+          CompressedData.new
+        when 9
+          SymmetricallyEncryptedData.new
+        when 10
+          Marker.new
+        when 11
+          Literal.new
+        when 12
+          Trust.new
+        when 13
+          UserId.new
+        when 14
+          PublicSubkey.new
+        when 17
+          UserAttribute.new
+        when 18
+          SymmetricEncryptedAndIntegrityProtectedData.new
+        when 19
+          MudificationDetectionCode.new
+        when 60..63
+          raise Error, 'Private or Experimental  Header detected'
+        else
+          nil
+        end
+      end
+    end
+  end
+end
+ 
diff --git a/lib/fpg/parse/new_packet.rb b/lib/fpg/parse/new_packet.rb
new file mode 100644
index 0000000..f4e7658
--- /dev/null
+++ b/lib/fpg/parse/new_packet.rb
@@ -0,0 +1,21 @@
+module FPG
+  module Parse
+    module NewPacketParser
+      def parse( stream )
+        size= packet_size( stream )
+        puts "i'm size "+size.to_s
+        stream.seek( size, IO::SEEK_CUR )
+      end
+      def packet_size( str )
+        tag = str.getbyte
+        return tag if tag < 192
+        return ((tag-192)<<8) + str.getbyte + 192 if tag < 224
+        return (str.getbyte<<24) | (str.getbyte<<16) | (str.getbyte<<8) | str.getbyte if tag == 255
+        raise Error, "Partial Body lengths are not supported"
+      end
+    end
+    class NewPacket < Packets::NewPacket
+      include NewPacketParser
+    end
+  end
+end
diff --git a/lib/fpg/parse/new_packet_header.rb b/lib/fpg/parse/new_packet_header.rb
new file mode 100644
index 0000000..a65a82e
--- /dev/null
+++ b/lib/fpg/parse/new_packet_header.rb
@@ -0,0 +1,23 @@
+module FPG
+  module Parse
+    class NewPacketHeader
+      include PacketHeaders
+      def parse( stream )
+        stream.each_byte do |byte|
+          current_packet = packet_for( byte )
+          unless current_packet.nil? then
+            puts current_packet.inspect
+            return current_packet.parse( stream )
+          end
+        end
+      end
+      def packet_size( str )
+        tag = str.getbyte
+        return tag if tag < 192
+        return ((tag-192)<<8) + str.getbyte + 192 if tag < 224
+        return (str.getbyte<<24) | (str.getbyte<<16) | (str.getbyte<<8) | str.getbyte if tag == 255
+        raise Error, "Partial Body lengths are not supported"
+      end
+    end
+end
+end
diff --git a/lib/fpg/parse/parser.rb b/lib/fpg/parse/parser.rb
new file mode 100644
index 0000000..3d0cd26
--- /dev/null
+++ b/lib/fpg/parse/parser.rb
@@ -0,0 +1,10 @@
+module FPG
+  module Parse
+    class Parser
+      def self.parse( stream )
+        #TODO: parse until stream at end
+        NewPacketHeader.new.parse( stream )
+      end
+    end
+  end
+end
diff --git a/lib/fpg/parse/signature.rb b/lib/fpg/parse/signature.rb
new file mode 100644
index 0000000..41bee87
--- /dev/null
+++ b/lib/fpg/parse/signature.rb
@@ -0,0 +1,10 @@
+module FPG
+  module Parse
+    module SignatureParser
+      include NewPacketParser
+    end
+    class Signature < Packets::Signature
+      include SignatureParser
+    end
+  end
+end
diff --git a/spec/radix64_spec.rb b/spec/radix64_spec.rb
index 73262d1..81c9bb6 100644
--- a/spec/radix64_spec.rb
+++ b/spec/radix64_spec.rb
@@ -1,8 +1,9 @@
-
 require File.join(File.dirname(__FILE__), %w[spec_helper])
 
 require 'stringio'
 
+include FPG::Io
+
 describe Radix64 do
   before(:each) do
    @radix = Radix64.new