From 0f656652e6d76deebcfc7834923adf99eadc050f Mon Sep 17 00:00:00 2001
From: obscuren <obscuren@obscura.com>
Date: Fri, 27 Dec 2013 23:48:44 +0100
Subject: [PATCH] Implemented decoding rlp

---
 rlp.go      | 51 +++++++++++++++++++++++++++++++++++++++++++++++----
 rlp_test.go | 15 ++++++++++++---
 2 files changed, 59 insertions(+), 7 deletions(-)

diff --git a/rlp.go b/rlp.go
index cce839095..2ea8ff094 100644
--- a/rlp.go
+++ b/rlp.go
@@ -1,7 +1,7 @@
 package main
 
 import (
-  _"fmt"
+  "fmt"
   "bytes"
   "math"
 )
@@ -40,11 +40,53 @@ func FromBin(data []byte) uint64 {
   return FromBin(data[:len(data)-1]) * 256 + uint64(data[len(data)-1])
 }
 
-func Decode(data []byte, pos int) {
+func Decode(data []byte, pos int) (interface{}, int) {
   char := int(data[pos])
+  slice := make([]interface{}, 0)
   switch {
   case char < 24:
+    return append(slice, data[pos]), pos + 1
+  case char < 56:
+    b := int(data[pos]) - 23
+    return FromBin(data[pos+1 : pos+1+b]), pos + 1 + b
+  case char < 64:
+    b := int(data[pos]) - 55
+    b2 := int(FromBin(data[pos+1 : pos+1+b]))
+    return FromBin(data[pos+1+b : pos+1+b+b2]), pos+1+b+b2
+  case char < 120:
+    b := int(data[pos]) - 64
+    return data[pos+1:pos+1+b], pos+1+b
+  case char < 128:
+    b := int(data[pos]) - 119
+    b2 := int(FromBin(data[pos+1 : pos+1+b]))
+    return data[pos+1+b : pos+1+b+b2], pos+1+b+b2
+  case char < 184:
+    b := int(data[pos]) - 128
+    pos++
+    for i := 0; i < b; i++ {
+      var obj interface{}
+
+      obj, pos = Decode(data, pos)
+      slice = append(slice, obj)
+    }
+    return slice, pos
+  case char < 192:
+    b := int(data[pos]) - 183
+    //b2 := int(FromBin(data[pos+1 : pos+1+b])) (ref imprementation has an unused variable)
+    pos = pos+1+b
+    for i := 0; i < b; i++ {
+      var obj interface{}
+
+      obj, pos = Decode(data, pos)
+      slice = append(slice, obj)
+    }
+    return slice, pos
+
+  default:
+    panic(fmt.Sprintf("byte not supported: %q", char))
   }
+
+  return slice, 0
 }
 
 func Encode(object interface{}) []byte {
@@ -86,10 +128,11 @@ func Encode(object interface{}) []byte {
     // Inline function for writing the slice header
     WriteSliceHeader := func(length int) {
       if length < 56 {
-        buff.WriteString(string(length + 128))
+        buff.WriteByte(byte(length + 128))
       } else {
         b2 := ToBin(uint64(length), 0)
-        buff.WriteString(string(len(b2) + 183) + b2)
+        buff.WriteByte(byte(len(b2) + 183))
+        buff.WriteString(b2)
       }
     }
 
diff --git a/rlp_test.go b/rlp_test.go
index 922b70978..c2d5ba263 100644
--- a/rlp_test.go
+++ b/rlp_test.go
@@ -7,14 +7,23 @@ import (
 
 func TestEncode(t *testing.T) {
   strRes := "Cdog"
-  str := string(Encode("dog"))
+  bytes := Encode("dog")
+  str := string(bytes)
   if str != strRes {
     t.Error(fmt.Sprintf("Expected %q, got %q", strRes, str))
   }
+  dec,_ := Decode(bytes, 0)
+  fmt.Printf("raw: %v encoded: %q == %v\n", dec, str, "dog")
 
-  sliceRes := "\u0083CdogCgodCcat"
-  slice := string(Encode([]string{"dog", "god", "cat"}))
+
+  sliceRes := "\x83CdogCgodCcat"
+  strs := []string{"dog", "god", "cat"}
+  bytes = Encode(strs)
+  slice := string(bytes)
   if slice != sliceRes {
     t.Error(fmt.Sprintf("Expected %q, got %q", sliceRes, slice))
   }
+
+  dec,_ = Decode(bytes, 0)
+  fmt.Printf("raw: %v encoded: %q == %v\n", dec, slice, strs)
 }