Support pointer ending label compression. Pull request merged: https://github.com/bluejekyll/trust-dns/pull/1182
--- a/src/rr/domain/name.rs
+++ b/src/rr/domain/name.rs
@@ -1322,6 +1322,42 @@ mod tests {
         assert_eq!(fourth, r_test);
     }
 
+    #[test]
+    fn test_pointer_with_pointer_ending_labels() {
+        let mut bytes: Vec<u8> = Vec::with_capacity(512);
+
+        let first = Name::from_str("ra.rb.rc").unwrap();
+        let second = Name::from_str("ra.rc").unwrap();
+        let third = Name::from_str("ra.rc").unwrap();
+
+        {
+            let mut e = BinEncoder::new(&mut bytes);
+
+            first.emit(&mut e).unwrap();
+            assert_eq!(e.len(), 10);
+
+            second.emit(&mut e).unwrap();
+            // +5 with the first +3 being the text form of "ra" and +2 for the pointer to "rc".
+            assert_eq!(e.len(), 15);
+
+            // +2 with the pointer to "ra.rc" as previously seen.
+            third.emit(&mut e).unwrap();
+            assert_eq!(e.len(), 17);
+        }
+
+        // now read them back
+        let mut d = BinDecoder::new(&bytes);
+
+        let r_test = Name::read(&mut d).unwrap();
+        assert_eq!(first, r_test);
+
+        let r_test = Name::read(&mut d).unwrap();
+        assert_eq!(second, r_test);
+
+        let r_test = Name::read(&mut d).unwrap();
+        assert_eq!(third, r_test);
+    }
+
     #[test]
     fn test_recursive_pointer() {
         // points to an invalid begining label marker
--- a/src/serialize/binary/encoder.rs
+++ b/src/serialize/binary/encoder.rs
@@ -91,8 +91,8 @@ mod private {
 pub struct BinEncoder<'a> {
     offset: usize,
     buffer: private::MaximalBuf<'a>,
-    /// start and end of label pointers, smallvec here?
-    name_pointers: Vec<(usize, usize)>,
+    /// start of label pointers with their labels in fully decompressed form for easy comparison, smallvec here?
+    name_pointers: Vec<(usize, Vec<u8>)>,
     mode: EncodeMode,
     canonical_names: bool,
 }
@@ -211,8 +211,7 @@ impl<'a> BinEncoder<'a> {
     pub fn trim(&mut self) {
         let offset = self.offset;
         self.buffer.truncate(offset);
-        self.name_pointers
-            .retain(|&(start, end)| start < offset && end <= offset);
+        self.name_pointers.retain(|&(start, _)| start < offset);
     }
 
     // /// returns an error if the maximum buffer size would be exceeded with the addition number of elements
@@ -243,7 +242,8 @@ impl<'a> BinEncoder<'a> {
         assert!(end <= (u16::max_value() as usize));
         assert!(start <= end);
         if self.offset < 0x3FFF_usize {
-            self.name_pointers.push((start, end)); // the next char will be at the len() location
+            self.name_pointers
+                .push((start, self.slice_of(start, end).to_vec())); // the next char will be at the len() location
         }
     }
 
@@ -251,11 +251,10 @@ impl<'a> BinEncoder<'a> {
     pub fn get_label_pointer(&self, start: usize, end: usize) -> Option<u16> {
         let search = self.slice_of(start, end);
 
-        for &(match_start, match_end) in &self.name_pointers {
-            let matcher = self.slice_of(match_start as usize, match_end as usize);
-            if matcher == search {
-                assert!(match_start <= (u16::max_value() as usize));
-                return Some(match_start as u16);
+        for (match_start, matcher) in &self.name_pointers {
+            if matcher.as_slice() == search {
+                assert!(match_start <= &(u16::max_value() as usize));
+                return Some(*match_start as u16);
             }
         }