Fixed #411 (very big DNS result over DoH).

src/dns/buffer.rs

@@ -166,6 +166,9 @@ impl VectorPacketBuffer {
 
 impl PacketBuffer for VectorPacketBuffer {
     fn read(&mut self) -> Result<u8> {
+        if self.pos >= self.buffer.len() {
+            return Err(BufferError::EndOfBuffer);
+        }
         let res = self.buffer[self.pos];
         self.pos += 1;
 
@@ -173,10 +176,16 @@ impl PacketBuffer for VectorPacketBuffer {
     }
 
     fn get(&mut self, pos: usize) -> Result<u8> {
+        if pos >= self.buffer.len() {
+            return Err(BufferError::EndOfBuffer);
+        }
         Ok(self.buffer[pos])
     }
 
     fn get_range(&mut self, start: usize, len: usize) -> Result<&[u8]> {
+        if start + len > self.buffer.len() {
+            return Err(BufferError::EndOfBuffer);
+        }
         Ok(&self.buffer[start..start + len as usize])
     }
 

src/dns/client.rs

@@ -617,7 +617,7 @@ impl DnsClient for HttpsDnsClient {
                                     Ok(size) => {
                                         let mut bytes: Vec<u8> = Vec::with_capacity(size);
                                         response.into_body().into_reader()
-                                            .take(4096)
+                                            .take(65535)
                                             .read_to_end(&mut bytes)?;
                                         let mut buffer = VectorPacketBuffer::new();
                                         buffer.buffer.extend_from_slice(bytes.as_slice());