adding docstrings

dnstp-server/src/main.rs

@@ -1,3 +1,5 @@
+//! DNS server component for processing requests and replying with DNS records
+
 use clap::Parser;
 use std::{thread};
 
@@ -9,6 +11,7 @@ use std::net::SocketAddr;
 use dnstplib::net::socket::DNSSocket;
 use dnstplib::processor::RequestProcesor;
 
+/// Command-line arguments for configuring the server
 #[derive(Parser, Debug)]
 #[command(author, version, about, long_about = None)]
 struct Args {

dnstp/src/byte.rs

@@ -1,18 +1,24 @@
+//! Utility functions for operating on bytes
 
+/// 8-bit mask for wiping out bits past a byte. Formatted as a 32-bit number
 const BYTEMASK_32: u32 = 0b11111111;
+/// 8-bit mask for wiping out bits past a byte. Formatted as a 16-bit number
 const BYTEMASK_16: u16 = 0b11111111;
 
+/// Take two sequential bytes starting from idx in buffer and return a concatenated 2 byte number
 pub fn two_byte_extraction(buffer: &[u8], idx: usize) -> u16
 {
     ((buffer[idx] as u16) << 8) | buffer[idx + 1] as u16
 }
 
+/// Take a 2 byte number and split it in to it's two 8 bit halves
 pub fn two_byte_split(num: u16) -> (u8, u8)
 {
     ((num >> 8) as u8,
      (num & BYTEMASK_16) as u8)
 }
 
+/// Split a 32 bit number into it's 8-bit quartered components
 pub fn four_byte_split(num: u32) -> (u8, u8, u8, u8)
 {
     ((num >> 24) as u8,

dnstp/src/message/answer.rs

@@ -1,5 +1,5 @@
 use crate::byte::{four_byte_split, two_byte_split};
-use crate::message::question::{QClass, QType};
+use crate::message::question::{DNSQuestion, QClass, QType};
 use crate::string::encode_domain_name;
 
 #[derive(Ord, PartialOrd, Eq, PartialEq, Debug)]
@@ -14,7 +14,7 @@ pub struct DNSAnswer {
 
 impl DNSAnswer {
 
-    pub fn to_bytes(& self) -> Vec<u8>
+    pub fn to_bytes(&self) -> Vec<u8>
     {
         let mut ret = encode_domain_name(&self.name);
 
@@ -40,4 +40,16 @@ impl DNSAnswer {
 
         return ret
     }
+}
+
+pub fn answers_to_bytes(answers: &Vec<DNSAnswer>) -> Vec<u8>
+{
+    let mut ret = Vec::with_capacity(20);
+
+    for a in answers
+    {
+        ret.append(&mut a.to_bytes());
+    }
+
+    ret
 }

dnstp/src/message/header.rs

@@ -2,14 +2,17 @@ use std::convert::TryFrom;
 use crate::byte::apply_split_bytes;
 use crate::message::header::Direction::Response;
 
+/// Size in bytes for a DNS message
 pub const HEADER_SIZE: usize = 12;
 
+/// Flag for whether the message represents a request or a response
 #[derive(Ord, PartialOrd, Eq, PartialEq, Debug, Copy, Clone)]
 pub enum Direction {
     Request = 0,
     Response = 1
 }
 
+/// Operation code for describing the purpose of the message
 #[derive(Ord, PartialOrd, Eq, PartialEq, Debug, Copy, Clone)]
 pub enum Opcode {
     Query = 0,
@@ -32,6 +35,7 @@ impl TryFrom<u16> for Opcode {
     }
 }
 
+/// What is the status of the request or response, what was the nature of the error, if encountered
 #[derive(Ord, PartialOrd, Eq, PartialEq, Debug, Copy, Clone)]
 pub enum ResponseCode {
     NoError = 0,
@@ -68,17 +72,23 @@ impl TryFrom<u16> for ResponseCode {
     }
 }
 
+/// Represents a header including flag fields and record counts
 #[derive(Ord, PartialOrd, Eq, PartialEq, Debug)]
 pub struct DNSHeader {
+    /// Random ID for associating responses with requests
     pub id: u16,
+    /// Is the message a request or the associated response
     pub direction: Direction,
+    /// What is the message function, e.g query, reverse DNS query
     pub opcode: Opcode,
     pub authoritative: bool,
     pub truncation: bool,
     pub recursion_desired: bool,
     pub recursion_available: bool,
     pub valid_zeroes: bool,
+    /// Status of the request or response
     pub response: ResponseCode,
+    /// Number of questions being made, should be the same in both the request and response
     pub question_count: u16,
     pub answer_record_count: u16,
     pub authority_record_count: u16,
@@ -86,6 +96,7 @@ pub struct DNSHeader {
 }
 
 impl DNSHeader {
+    /// Serialise a header memory structure back into bytes for putting on the wire
     pub fn to_bytes(&self) -> [u8; 12]
     {
         let mut header_bytes: [u8; 12] = [0; 12];

dnstp/src/message/response.rs

@@ -1,5 +1,5 @@
 use std::net::SocketAddr;
-use crate::message::answer::DNSAnswer;
+use crate::message::answer::{answers_to_bytes, DNSAnswer};
 use crate::message::header::DNSHeader;
 use crate::message::question::{DNSQuestion, questions_to_bytes};
 
@@ -17,8 +17,10 @@ impl DNSResponse {
     {
         let mut header_bytes = self.header.to_bytes().to_vec();
         let mut body_bytes = questions_to_bytes(&self.questions);
+        let mut answer_bytes = answers_to_bytes(&self.answers);
 
         header_bytes.append(&mut body_bytes);
+        header_bytes.append(&mut answer_bytes);
 
         return header_bytes
     }