Bugfix: routing_key or exchange with length 255 no launger causes an ArithmeticOverflow (#1094)

fixes a bug where using routing_key or exchange with length 255 causes an ArithmeticOverflow. 

Fixes #1093

Author: viktorerlingsson

spec/storage_spec.cr

@@ -164,6 +164,31 @@ describe LavinMQ::AMQP::DurableQueue do
       end
     end
   end
+
+  # ArithmeticOverflow error when routing key length = 255
+  # https://github.com/cloudamqp/lavinmq/issues/1093
+  it "should handle routing key length = 255" do
+    rk = "a" * 255
+    with_amqp_server do |s|
+      vhost = s.vhosts.create("test_vhost")
+      with_channel(s, vhost: vhost.name) do |ch|
+        q = ch.queue(rk, durable: true)
+        queue = vhost.queues[rk].as(LavinMQ::AMQP::DurableQueue)
+        q.publish_confirm "a"
+        store = LavinMQ::Queue::MessageStore.new(queue.@msg_store.@queue_data_dir, nil)
+
+        if env = store.shift?
+          if msg = env.message
+            msg.routing_key.should eq rk
+          else
+            fail "no message"
+          end
+        else
+          fail "no message"
+        end
+      end
+    end
+  end
 end
 
 describe LavinMQ::VHost do

src/lavinmq/message.cr

@@ -38,8 +38,8 @@ module LavinMQ
     def self.skip(io, format = IO::ByteFormat::SystemEndian) : UInt64
       skipped = 0_u64
       skipped += io.skip(sizeof(UInt64))                             # ts
-      skipped += io.skip(io.read_byte || raise IO::EOFError.new) + 1 # ex
-      skipped += io.skip(io.read_byte || raise IO::EOFError.new) + 1 # rk
+      skipped += 1 + io.skip(io.read_byte || raise IO::EOFError.new) # ex
+      skipped += 1 + io.skip(io.read_byte || raise IO::EOFError.new) # rk
       skipped += AMQ::Protocol::Properties.skip(io, format)
       skipped += io.skip(UInt64.from_io io, format) + sizeof(UInt64)
       skipped