lib/distack/urlsign/signer.rb in distack-urlsign-0.1.0 vs lib/distack/urlsign/signer.rb in distack-urlsign-0.2.0

@@ -1,6 +1,8 @@
 module Distack::URLSign
+  InvalidSignatureError = Class.new(StandardError)
+
   class Signer
     KEY_REGEX = /^[0-9A-f]+$/
 
     def initialize(hex_key)
       if hex_key !~ KEY_REGEX
@@ -10,28 +12,55 @@
       @key = [hex_key].pack("H*")
     end
 
     def sign(url)
       if url.opaque
-        raise "can't sign or verify opaque URL"
+        raise "can't sign opaque URL"
       end
 
       chunks = [url.scheme, "#{url.host}:#{url.port}", url.path, url.query, url.userinfo].compact
       digest = OpenSSL::Digest.new("sha512")
 
       rawsig    = OpenSSL::HMAC.digest(digest, @key, chunks.join)
       signature = Base64.urlsafe_encode64(rawsig)
 
       if url.query
-        q = URI.decode_www_form(url.query)
+        q = Rack::Utils.parse_nested_query(url.query)
       else
-        q = []
+        q = {}
       end
 
-      q << ["_signature", signature]
+      q ["_signature"] = signature
 
       new_url = url.dup
-      new_url.query = URI.encode_www_form(q)
+      new_url.query = Rack::Utils.build_nested_query(q)
       new_url
+    end
+
+    def verify(url)
+      if url.opaque
+        raise "can't verify opaque URL"
+      end
+
+      q = Rack::Utils.parse_nested_query(url.query)
+
+      original_q  = q.dup
+      original_q.delete("_signature")
+
+      original_qs = Rack::Utils.build_nested_query(original_q)
+
+      chunks = [url.scheme, "#{url.host}:#{url.port}", url.path, original_qs, url.userinfo].compact
+      digest = OpenSSL::Digest.new("sha512")
+
+      rawsig    = OpenSSL::HMAC.digest(digest, @key, chunks.join)
+      signature = Base64.urlsafe_encode64(rawsig)
+
+      if signature == q["_signature"]
+        new_url = url.dup
+        new_url.query = original_qs
+        new_url
+      else
+        raise InvalidSignatureError, "signature is invalid for #{url}"
+      end
     end
   end
 end