Update examples with modernized code

examples/sample2.rs

@@ -164,9 +164,7 @@ impl BytePacketBuffer {
     }
 
     fn write_qname(&mut self, qname: &str) -> Result<()> {
-        let split_str = qname.split('.').collect::<Vec<&str>>();
-
-        for label in split_str {
+        for label in qname.split('.') {
             let len = label.len();
             if len > 0x34 {
                 return Err("Single label exceeds 63 characters of length".into());
@@ -521,12 +519,18 @@ impl DnsPacket {
 }
 
 fn main() -> Result<()> {
-    let qname = "www.yahoo.com";
+    // Perform an A query for google.com
+    let qname = "google.com";
     let qtype = QueryType::A;
+
+    // Using googles public DNS server
     let server = ("8.8.8.8", 53);
 
+    // Bind a UDP socket to an arbitrary port
     let socket = UdpSocket::bind(("0.0.0.0", 43210))?;
 
+    // Build our query packet. It's important that we remember to set the
+    // `recursion_desired` flag. As noted earlier, the packet id is arbitrary.
     let mut packet = DnsPacket::new();
 
     packet.header.id = 6666;
@@ -536,27 +540,34 @@ fn main() -> Result<()> {
         .questions
         .push(DnsQuestion::new(qname.to_string(), qtype));
 
+    // Use our new write method to write the packet to a buffer...
     let mut req_buffer = BytePacketBuffer::new();
     packet.write(&mut req_buffer)?;
+
+    // ...and send it off to the server using our socket:
     socket.send_to(&req_buffer.buf[0..req_buffer.pos], server)?;
 
+    // To prepare for receiving the response, we'll create a new `BytePacketBuffer`,
+    // and ask the socket to write the response directly into our buffer.
     let mut res_buffer = BytePacketBuffer::new();
     socket.recv_from(&mut res_buffer.buf)?;
 
+    // As per the previous section, `DnsPacket::from_buffer()` is then used to
+    // actually parse the packet after which we can print the response.
     let res_packet = DnsPacket::from_buffer(&mut res_buffer)?;
-    println!("{:?}", res_packet.header);
+    println!("{:#?}", res_packet.header);
 
     for q in res_packet.questions {
-        println!("{:?}", q);
+        println!("{:#?}", q);
     }
     for rec in res_packet.answers {
-        println!("{:?}", rec);
+        println!("{:#?}", rec);
     }
     for rec in res_packet.authorities {
-        println!("{:?}", rec);
+        println!("{:#?}", rec);
     }
     for rec in res_packet.resources {
-        println!("{:?}", rec);
+        println!("{:#?}", rec);
     }
 
     Ok(())