docs: handshake documentation

proto/src/handshake/client.rs

@@ -7,15 +7,20 @@ use crate::reader::backend::BackendProtoReader;
 use crate::writer::frontend::FrontendProtoWriter;
 use crate::writer::protowriter::ProtoFlush;
 
+/// Performs client-side handshake with the server until the `ReadyForQuery` message is received.
+/// For more info visit the [`55.2.1. Start-up`](https://www.postgresql.org/docs/current/protocol-flow.html#PROTOCOL-FLOW-START-UP)
 pub async fn do_client_handshake(
     writer: &mut (impl FrontendProtoWriter + ProtoFlush),
     reader: &mut impl BackendProtoReader,
     request: HandshakeRequest,
 ) -> Result<HandshakeResponse, ClientHandshakeError> {
+
+    //  Send StartupMessage without SSLRequest
     let startup_message: StartupMessageData = request.into();
     writer.write_startup_message(startup_message).await?;
     writer.flush().await?;
 
+    //  Wait for AuthenticationOk
     let auth = reader.read_proto().await?;
     if !matches!(
         auth,
@@ -24,6 +29,7 @@ pub async fn do_client_handshake(
         return Err(ClientHandshakeError::UnexpectedAuthResponse(auth));
     }
 
+    //  Read server parameter messages until ReadyForQuery is received
     let mut messages = Vec::new();
     loop {
         let msg = reader.read_proto().await?;