Test that a write reply with the wrong magic will force a retry

tests/acceptance/fakes/dest/write_wrong_magic.rb

@@ -0,0 +1,24 @@
+#!/usr/bin/env ruby
+# encoding: utf-8
+
+# Accept a connection, write hello, wait for a write request, read the
+# data, then write back a reply with a bad magic field.  We then
+# expect a reconnect.
+
+require 'flexnbd/fake_dest'
+include FlexNBD
+
+addr, port = *ARGV
+server = FakeDest.new( addr, port )
+
+client = server.accept
+client.write_hello
+req = client.read_request
+client.read_data( req[:len] )
+client.write_reply( req[:handle], 0, :magic => :wrong )
+
+client2 = server.accept
+client.close
+client2.close
+
+exit(0)

tests/acceptance/flexnbd/fake_dest.rb

@@ -56,10 +56,21 @@ module FlexNBD
         }
       end
 
+      REPLY_MAGIC="\x67\x44\x66\x98"
 
       def write_error( handle )
-        @sock.write( "\x67\x44\x66\x98" )
-        @sock.write( "\x00\x00\x00\x01" )
+        write_reply( handle, 1 )
+      end
+
+
+      def write_reply( handle, err=0, opts={} )
+        if opts[:magic] == :wrong
+          write_rand( @sock, 4 )
+        else
+          @sock.write( REPLY_MAGIC )
+        end
+
+        @sock.write( [err].pack("N") )
         @sock.write( handle )
       end
 
@@ -69,6 +80,10 @@ module FlexNBD
       end
 
 
+      def read_data( len )
+        @sock.read( len )
+      end
+
 
       def self.parse_be64(str)
         raise "String is the wrong length: 8 bytes expected (#{str.length} received)" unless

tests/acceptance/test_source_error_handling.rb

@@ -89,6 +89,13 @@ class TestSourceErrorHandling < Test::Unit::TestCase
   end
 
 
+  def test_bad_write_reply_causes_retry
+    run_fake( "dest/write_wrong_magic" )
+    @env.mirror12_unchecked
+    assert_success
+  end
+
+
   private
   def run_fake(name)
     @env.run_fake( name, @env.ip, @env.port2 )