working startup

src/client.rs

@@ -0,0 +1,64 @@
+/// PostgreSQL client (frontend).
+/// We are pretending to be the backend.
+
+use tokio::net::TcpStream;
+use tokio::io::{AsyncReadExt, AsyncWriteExt};
+
+use bytes::{BytesMut, Buf, BufMut};
+
+use crate::errors::Error;
+use crate::messages::*;
+
+pub struct Client {
+    stream: TcpStream,
+}
+
+impl Client {
+    pub async fn startup(mut stream: TcpStream) -> Result<Client, Error> {
+        loop {
+            // Could be StartupMessage or SSLRequest
+            // which makes this variable length.
+            let len = match stream.read_i32().await {
+                Ok(len) => len,
+                Err(_) => return Err(Error::ClientBadStartup),
+            };
+
+            // Read whatever is left.
+            let mut startup = vec![0u8; len as usize - 4];
+
+            match stream.read_exact(&mut startup).await {
+                Ok(_) => (),
+                Err(_) => return Err(Error::ClientBadStartup),
+            };
+
+            let mut bytes = BytesMut::from(&startup[..]);
+            let code = bytes.get_i32();
+
+            match code {
+                // Client wants SSL. We don't support it at the moment.
+                80877103 => {
+                    let mut no = BytesMut::with_capacity(1);
+                    no.put_u8(b'N');
+
+                    write_all(&mut stream, no).await?;
+                },
+
+                // Regular startup message.
+                196608 => {
+                    // TODO: perform actual auth.
+                    // TODO: record startup parameters client sends over.
+                    auth_ok(&mut stream).await?;
+                    ready_for_query(&mut stream).await?;
+
+                    return Ok(Client {
+                        stream: stream,
+                    });
+                },
+
+                _ => {
+                    return Err(Error::ProtocolSyncError);
+                }
+            };
+        }
+    }
+}