[2087] Add the LabelSequence::getOffsetData() method

src/lib/dns/labelsequence.cc

@@ -29,6 +29,15 @@ LabelSequence::getData(size_t *len) const {
     return &(data_[offsets_[first_label_]]);
 }
 
+void
+LabelSequence::getOffsetData(size_t* len,
+                             uint8_t placeholder[Name::MAX_LABELS]) const {
+  *len = last_label_ - first_label_;
+  for (size_t i = 0; i < *len; i++) {
+      placeholder[i] = offsets_[first_label_ + i] - offsets_[first_label_];
+  }
+}
+
 size_t
 LabelSequence::getDataLength() const {
     // If the labelsequence is absolute, the current last_label_ falls

src/lib/dns/labelsequence.h

@@ -96,6 +96,16 @@ public:
     /// \return Pointer to the wire-format data of this label sequence
     const uint8_t* getData(size_t* len) const;
 
+    /// \brief Return the offset data for this LabelSequence
+    ///
+    /// The offsets are returned in the <code>placeholder</code> array.
+    ///
+    /// \param len Pointer to a size_t where the number of offsets
+    ///        will be stored
+    /// \param placeholder Array where the offset data will be returned
+    void getOffsetData(size_t* len,
+                       uint8_t placeholder[Name::MAX_LABELS]) const;
+
     /// \brief Return the length of the wire-format data of this LabelSequence
     ///
     /// This method returns the number of octets for the data that would

src/lib/dns/tests/labelsequence_unittest.cc

@@ -400,6 +400,93 @@ TEST_F(LabelSequenceTest, getData) {
     getDataCheck("\000", 1, ls7);
 };
 
+TEST_F(LabelSequenceTest, getOffsetData) {
+    size_t len;
+    uint8_t placeholder[Name::MAX_LABELS];
+
+    Name nx("x.isc.example.org");
+    LabelSequence lsx(nx);
+
+    // x.isc.example.org.
+    lsx.getOffsetData(&len, placeholder);
+    EXPECT_EQ(5, len);
+    EXPECT_EQ(0, placeholder[0]);
+    EXPECT_EQ(2, placeholder[1]);
+    EXPECT_EQ(6, placeholder[2]);
+    EXPECT_EQ(14, placeholder[3]);
+    EXPECT_EQ(18, placeholder[4]);
+
+    lsx.stripLeft(2);
+
+    // example.org.
+    lsx.getOffsetData(&len, placeholder);
+    EXPECT_EQ(3, len);
+    EXPECT_EQ(0, placeholder[0]);
+    EXPECT_EQ(8, placeholder[1]);
+    EXPECT_EQ(12, placeholder[2]);
+
+    lsx.stripLeft(1);
+
+    // org.
+    lsx.getOffsetData(&len, placeholder);
+    EXPECT_EQ(2, len);
+    EXPECT_EQ(0, placeholder[0]);
+    EXPECT_EQ(4, placeholder[1]);
+
+    lsx.stripLeft(1);
+
+    // .
+    lsx.getOffsetData(&len, placeholder);
+    EXPECT_EQ(1, len);
+    EXPECT_EQ(0, placeholder[0]);
+
+    Name ny("y.isc.example.org");
+    LabelSequence lsy(ny);
+
+    // y.isc.example.org.
+    lsy.getOffsetData(&len, placeholder);
+    EXPECT_EQ(5, len);
+    EXPECT_EQ(0, placeholder[0]);
+    EXPECT_EQ(2, placeholder[1]);
+    EXPECT_EQ(6, placeholder[2]);
+    EXPECT_EQ(14, placeholder[3]);
+    EXPECT_EQ(18, placeholder[4]);
+
+    lsy.stripRight(1);
+
+    // y.isc.example.org
+    lsy.getOffsetData(&len, placeholder);
+    EXPECT_EQ(4, len);
+    EXPECT_EQ(0, placeholder[0]);
+    EXPECT_EQ(2, placeholder[1]);
+    EXPECT_EQ(6, placeholder[2]);
+    EXPECT_EQ(14, placeholder[3]);
+
+    lsy.stripRight(1);
+
+    // y.isc.example
+    lsy.getOffsetData(&len, placeholder);
+    EXPECT_EQ(3, len);
+    EXPECT_EQ(0, placeholder[0]);
+    EXPECT_EQ(2, placeholder[1]);
+    EXPECT_EQ(6, placeholder[2]);
+
+    lsy.stripLeft(1);
+
+    // isc.example
+    lsy.getOffsetData(&len, placeholder);
+    EXPECT_EQ(2, len);
+    EXPECT_EQ(0, placeholder[0]);
+    EXPECT_EQ(4, placeholder[1]);
+
+    lsy.stripLeft(1);
+
+    // example
+    lsy.getOffsetData(&len, placeholder);
+    EXPECT_EQ(1, len);
+    EXPECT_EQ(0, placeholder[0]);
+};
+
 TEST_F(LabelSequenceTest, stripLeft) {
     EXPECT_TRUE(ls1.equals(ls3));
     ls1.stripLeft(0);