[2442] rejected extra \n for std::string version of txt-like ctor.

src/lib/dns/rdata/generic/detail/txt_like.h

@@ -88,9 +88,14 @@ public:
 
         try {
             buildFromTextHelper(lexer);
+            if (lexer.getNextToken().getType() != MasterToken::END_OF_FILE) {
+                isc_throw(InvalidRdataText, "Failed to construct " <<
+                          RRType(typeCode) << " RDATA from '" << txtstr <<
+                          "': extra new line");
+            }
         } catch (const MasterLexer::LexerError& ex) {
             isc_throw(InvalidRdataText, "Failed to construct " <<
-                      RRType(typeCode) << " RDATA from " << txtstr << ": "
+                      RRType(typeCode) << " RDATA from '" << txtstr << "': "
                       << ex.what());
         }
     }

src/lib/dns/tests/rdata_txt_like_unittest.cc

@@ -214,6 +214,14 @@ TYPED_TEST(Rdata_TXT_LIKE_Test, createMultiStringsFromText) {
     }
 }
 
+TYPED_TEST(Rdata_TXT_LIKE_Test, createFromTextExtra) {
+    // This is for the std::string version only: the input must end with EOF;
+    // an extra new-line will result in an exception.
+    EXPECT_THROW(TypeParam("\"Test-String\"\n"), InvalidRdataText);
+    // Same if there's a space before '\n'
+    EXPECT_THROW(TypeParam("\"Test-String\" \n"), InvalidRdataText);
+}
+
 TYPED_TEST(Rdata_TXT_LIKE_Test, fromTextEmpty) {
     // If the input text doesn't contain any character-string, it should be
     // rejected