serve: Make some error conditions non-fatal, test them.

We don't want flexnbd serve to fall over and die if the client sends an invalid request.

tests/acceptance/test_serve_mode.rb

@@ -0,0 +1,86 @@
+require 'test/unit'
+require 'environment'
+require 'flexnbd/fake_source'
+
+class TestServeMode < Test::Unit::TestCase
+
+  def setup
+    super
+    @env = Environment.new
+    @env.writefile1( "0" )
+    @env.serve1
+  end
+
+  def teardown
+    @env.cleanup
+    super
+  end
+
+  def connect_to_server
+    client = FlexNBD::FakeSource.new(@env.ip, @env.port1, "Connecting to server failed")
+    begin
+      result = client.read_hello
+      assert_equal "NBDMAGIC", result[:magic]
+      assert_equal @env.file1.size, result[:size]
+      yield client
+    ensure
+      client.close rescue nil
+    end
+  end
+
+  def test_bad_request_magic_receives_error_response
+    connect_to_server do |client|
+
+      # replace REQUEST_MAGIC with all 0s to make it look bad
+      client.send_request( 0, "myhandle", 0, 0, "\x00\x00\x00\x00" )
+      rsp = client.read_response
+
+      assert_equal FlexNBD::REPLY_MAGIC, rsp[:magic]
+      assert_equal "myhandle", rsp[:handle]
+      assert rsp[:error] != 0, "Server sent success reply back: #{rsp[:error]}"
+
+      # The client should be disconnected now
+      assert client.disconnected?, "Server not disconnected"
+    end
+  end
+
+
+  def test_read_request_out_of_bounds_receives_error_response
+    connect_to_server do |client|
+      client.write_read_request( @env.file1.size, 4096 )
+      rsp = client.read_response
+
+      assert_equal FlexNBD::REPLY_MAGIC, rsp[:magic]
+      assert_equal "myhandle", rsp[:handle]
+      assert rsp[:error] != 0, "Server sent success reply back: #{rsp[:error]}"
+
+      # Ensure we're not disconnected by sending a request. We don't care about
+      # whether the reply is good or not, here.
+      client.write_read_request( 0, 4096 )
+      rsp = client.read_response
+      assert_equal FlexNBD::REPLY_MAGIC, rsp[:magic]
+    end
+  end
+
+  def test_write_request_out_of_bounds_receives_error_response
+    connect_to_server do |client|
+      client.write( @env.file1.size, "\x00" * 4096 )
+      rsp = client.read_response
+
+      assert_equal FlexNBD::REPLY_MAGIC, rsp[:magic]
+      assert_equal "myhandle", rsp[:handle]
+      assert rsp[:error] != 0, "Server sent success reply back: #{rsp[:error]}"
+
+      # Ensure we're not disconnected by sending a request. We don't care about
+      # whether the reply is good or not, here.
+      client.write( 0, "\x00" * @env.file1.size )
+      rsp = client.read_response
+      assert_equal FlexNBD::REPLY_MAGIC, rsp[:magic]
+    end
+
+  end
+
+
+
+end
+