Fix newline escaping in line protocol (#3992)

plugins/parsers/influx/machine.go.rl

@@ -142,7 +142,7 @@ fieldfloat =
 fieldinteger =
 	(integer 'i') >begin %integer;
 
-fieldunsigned = 
+fieldunsigned =
 	(unsigned 'u') >begin %unsigned;
 
 false =
@@ -155,7 +155,7 @@ fieldbool =
 	(true | false) >begin %bool;
 
 fieldstringchar =
-	[^\\"] | '\\' [\\"];
+	[^\n\f\r\\"] | '\\' [\\"];
 
 fieldstring =
 	fieldstringchar* >begin %string;

plugins/parsers/influx/machine_test.go

@@ -1154,6 +1154,22 @@ var tests = []struct {
 			},
 		},
 	},
+	{
+		name:  "invalid newline in string field",
+		input: []byte("cpu value=\"4\n2\""),
+		results: []Result{
+			Result{
+				Name:  Measurement,
+				Value: []byte("cpu"),
+			},
+			Result{
+				err: ErrFieldParse,
+			},
+			Result{
+				err: ErrFieldParse,
+			},
+		},
+	},
 	{
 		name:  "invalid field value",
 		input: []byte(`cpu value=howdy`),