stream.peer_addr() & auth_query (#575)

* Don't unwrap stream.peer_addr()

https://github.com/postgresml/pgcat/pull/562 (same code)
(another lines changed)

* auth_query (real sample)

# single quote need
auth_query="SELECT usename, passwd FROM pg_shadow WHERE usename='$1'"

pgcat.toml

@@ -187,7 +187,7 @@ sharding_function = "pg_bigint_hash"
 # Query to be sent to servers to obtain the hash used for md5 authentication. The connection will be
 # established using the database configured in the pool. This parameter is inherited by every pool
 # and can be redefined in pool configuration.
-# auth_query = "SELECT $1"
+# auth_query="SELECT usename, passwd FROM pg_shadow WHERE usename='$1'"
 
 # User to be used for connecting to servers to obtain the hash used for md5 authentication by sending the query
 # specified in `auth_query_user`. The connection will be established using the database configured in the pool.

src/client.rs

@@ -117,7 +117,15 @@ pub async fn client_entrypoint(
     log_client_connections: bool,
 ) -> Result<(), Error> {
     // Figure out if the client wants TLS or not.
-    let addr = stream.peer_addr().unwrap();
+    let addr = match stream.peer_addr() {
+        Ok(addr) => addr,
+        Err(err) => {
+            return Err(Error::SocketError(format!(
+                "Failed to get peer address: {:?}",
+                err
+            )));
+        }
+    };
 
     match get_startup::<TcpStream>(&mut stream).await {
         // Client requested a TLS connection.