docs: add comments (and blank lines)

src/lib.rs

@@ -46,43 +46,68 @@ impl From<rustls::ClientConfig> for Client {
 impl Client {
     pub async fn request(self: &Self, url_str: &str) -> Result<Response, LibError> {
         let url = Url::parse(url_str).map_err(|e| InvalidUrl::ParseError(e))?;
+        // for proxying http(s) through gemini server,
+        // use Client::request_with_host
         if url.scheme() != "gemini" {
+            // deny non-Gemini req
             return Err(InvalidUrl::SchemeNotGemini.into());
         }
+        // userinfo (user:pswd@) is not allowed in Gemini
         if !url.username().is_empty() {
             return Err(InvalidUrl::UserinfoPresent.into());
         }
+
         let host = url.host_str().ok_or(InvalidUrl::ConvertError)?;
         let addr = (host, url.port().unwrap_or(1965))
             .to_socket_addrs()?
             .next()
             .ok_or(InvalidUrl::ConvertError)?;
+
         let domain = pki_types::ServerName::try_from(host)
             .map_err(|_| InvalidUrl::ConvertError)?
             .to_owned();
+
         let stream = TcpStream::connect(&addr).await?;
         let mut stream = self.connector.connect(domain, stream).await?;
+
+        // Write URL, then CRLF
         stream.write_all(url_str.as_bytes()).await?;
         stream.write_all(b"\r\n").await?;
+
         let mut buf: [u8; 3] = [0, 0, 0]; // 2 digits, space
         stream.read_exact(&mut buf).await?;
         let status = Status::parse_status(&buf)?;
+
         let mut message: Vec<u8> = Vec::new();
         let mut buf_reader = tokio::io::BufReader::new(&mut stream);
-        let mut buf: [u8; 1] = [0];
+        let mut buf: [u8; 1] = [0]; // buffer for LF (\n)
+
+        // reading message after status code
+        // until CRLF (\r\n)
         loop {
+            // until CR
             buf_reader.read_until(b'\r', &mut message).await?;
+            // now read next char...
             buf_reader.read_exact(&mut buf).await?;
             if buf[0] == b'\n' {
+                // ...and check if it's LF
                 break;
             } else {
+                // ...otherwise, CR is a part of message, not a CRLF terminator,
+                // so append that one byte that's supposed to be LF (but not LF)
+                // to the message buffer
                 message.push(buf[0].into());
             }
         }
+
+        // trim last CR
         if message.last().is_some_and(|c| c == &b'\r') {
             message.pop();
         }
+
+        // Vec<u8> -> ASCII or UTF-8 String
         let message = String::from_utf8(message)?;
+
         Ok(Response::new(status, message, stream))
     }
 }

src/status.rs

@@ -54,11 +54,16 @@ const ASCII_ZERO: u8 = 48; // '0'
 
 impl Status {
     pub fn parse_status(buf: &[u8]) -> Result<Self, LibError> {
+        // simple decimal digit conversion
+        // '2' - '0' = 50 - 48 = 2 (from byte '2' to uint 2)
         let first = buf[0] - ASCII_ZERO;
         let second = buf[1] - ASCII_ZERO;
         Ok(Status {
+            // get enum item for 2-digit status code
             status_code: StatusCode::try_from_primitive(first * 10 + second)?,
+            // get enum entry for first digit
             reply_type: ReplyType::try_from_primitive(first)?,
+            // provide separate field for the 2nd digit
             second_digit: second,
         })
     }