Rewrite entire codebase to split into client and server

src/core/bootstrap.rs

@@ -0,0 +1,177 @@
+use std::{fs, path::PathBuf};
+
+use anyhow::Context;
+use nix::libc::{exit, EXIT_SUCCESS};
+use std::os::unix::net::UnixStream as StdUnixStream;
+use tokio::net::UnixStream as TokioUnixStream;
+
+use crate::{
+    core::{
+        bootstrap::authenticated_unix_socket::client_authenticate,
+        common::{UnixUser, DEFAULT_CONFIG_PATH, DEFAULT_SOCKET_PATH},
+    },
+    server::{config::read_config_form_path, server_loop::handle_requests_for_single_session},
+};
+
+pub mod authenticated_unix_socket;
+
+// TODO: this function is security critical, it should be integration tested
+//       in isolation.
+/// Drop privileges to the real user and group of the process.
+/// If the process is not running with elevated privileges, this function
+/// is a no-op.
+pub fn drop_privs() -> anyhow::Result<()> {
+    log::debug!("Dropping privileges");
+    let real_uid = nix::unistd::getuid();
+    let real_gid = nix::unistd::getgid();
+
+    nix::unistd::setuid(real_uid).context("Failed to drop privileges")?;
+    nix::unistd::setgid(real_gid).context("Failed to drop privileges")?;
+
+    debug_assert_eq!(nix::unistd::getuid(), real_uid);
+    debug_assert_eq!(nix::unistd::getgid(), real_gid);
+
+    log::debug!("Privileges dropped successfully");
+    Ok(())
+}
+
+/// This function is used to bootstrap the connection to the server.
+/// This can happen in two ways:
+/// 1. If a socket path is provided, or exists in the default location,
+///    the function will connect to the socket and authenticate with the
+///    server to ensure that the server knows the uid of the client.
+/// 2. If a config path is provided, or exists in the default location,
+///    and the config is readable, the function will assume it is either
+///    setuid or setgid, and will fork a child process to run the server
+///    with the provided config. The server will exit silently by itself
+///    when it is done, and this function will only return for the client
+///    with the socket for the server.
+/// If neither of these options are available, the function will fail.
+pub fn bootstrap_server_connection_and_drop_privileges(
+    server_socket_path: Option<PathBuf>,
+    config_path: Option<PathBuf>,
+) -> anyhow::Result<StdUnixStream> {
+    if server_socket_path.is_some() && config_path.is_some() {
+        anyhow::bail!("Cannot provide both a socket path and a config path");
+    }
+
+    log::debug!("Starting the server connection bootstrap process");
+
+    let (socket, do_authenticate) = bootstrap_server_connection(server_socket_path, config_path)?;
+
+    drop_privs()?;
+
+    let result: anyhow::Result<StdUnixStream> = if do_authenticate {
+        tokio::runtime::Builder::new_current_thread()
+            .enable_all()
+            .build()
+            .unwrap()
+            .block_on(async {
+                let mut socket = TokioUnixStream::from_std(socket)?;
+                client_authenticate(&mut socket, None).await?;
+                Ok(socket.into_std()?)
+            })
+    } else {
+        Ok(socket)
+    };
+
+    result
+}
+
+/// Inner function for [`bootstrap_server_connection_and_drop_privileges`].
+/// See that function for more information.
+fn bootstrap_server_connection(
+    socket_path: Option<PathBuf>,
+    config_path: Option<PathBuf>,
+) -> anyhow::Result<(StdUnixStream, bool)> {
+    // TODO: ensure this is both readable and writable
+    if let Some(socket_path) = socket_path {
+        log::debug!("Connecting to socket at {:?}", socket_path);
+        return match StdUnixStream::connect(socket_path) {
+            Ok(socket) => Ok((socket, true)),
+            Err(e) => match e.kind() {
+                std::io::ErrorKind::NotFound => Err(anyhow::anyhow!("Socket not found")),
+                std::io::ErrorKind::PermissionDenied => Err(anyhow::anyhow!("Permission denied")),
+                _ => Err(anyhow::anyhow!("Failed to connect to socket: {}", e)),
+            },
+        };
+    }
+    if let Some(config_path) = config_path {
+        // ensure config exists and is readable
+        if fs::metadata(&config_path).is_err() {
+            return Err(anyhow::anyhow!("Config file not found or not readable"));
+        }
+
+        log::debug!("Starting server with config at {:?}", config_path);
+        return invoke_server_with_config(config_path).map(|socket| (socket, false));
+    }
+
+    if fs::metadata(DEFAULT_SOCKET_PATH).is_ok() {
+        return match StdUnixStream::connect(DEFAULT_SOCKET_PATH) {
+            Ok(socket) => Ok((socket, true)),
+            Err(e) => match e.kind() {
+                std::io::ErrorKind::NotFound => Err(anyhow::anyhow!("Socket not found")),
+                std::io::ErrorKind::PermissionDenied => Err(anyhow::anyhow!("Permission denied")),
+                _ => Err(anyhow::anyhow!("Failed to connect to socket: {}", e)),
+            },
+        };
+    }
+
+    let config_path = PathBuf::from(DEFAULT_CONFIG_PATH);
+    if fs::metadata(&config_path).is_ok() {
+        return invoke_server_with_config(config_path).map(|socket| (socket, false));
+    }
+
+    anyhow::bail!("No socket path or config path provided, and no default socket or config found");
+}
+
+// TODO: we should somehow ensure that the forked process is killed on completion,
+//       just in case the client does not behave properly.
+/// Fork a child process to run the server with the provided config.
+/// The server will exit silently by itself when it is done, and this function
+/// will only return for the client with the socket for the server.
+fn invoke_server_with_config(config_path: PathBuf) -> anyhow::Result<StdUnixStream> {
+    let (server_socket, client_socket) = StdUnixStream::pair()?;
+    let unix_user = UnixUser::from_uid(nix::unistd::getuid().as_raw())?;
+
+    match (unsafe { nix::unistd::fork() }).context("Failed to fork")? {
+        nix::unistd::ForkResult::Parent { child } => {
+            log::debug!("Forked child process with PID {}", child);
+            Ok(client_socket)
+        }
+        nix::unistd::ForkResult::Child => {
+            log::debug!("Running server in child process");
+
+            match run_forked_server(config_path, server_socket, unix_user) {
+                Err(e) => Err(e),
+                Ok(_) => unreachable!(),
+            }
+        }
+    }
+}
+
+/// Run the server in the forked child process.
+/// This function will not return, but will exit the process with a success code.
+fn run_forked_server(
+    config_path: PathBuf,
+    server_socket: StdUnixStream,
+    unix_user: UnixUser,
+) -> anyhow::Result<()> {
+    let config = read_config_form_path(Some(config_path))?;
+
+    let result: anyhow::Result<()> = tokio::runtime::Builder::new_current_thread()
+        .enable_all()
+        .build()
+        .unwrap()
+        .block_on(async {
+            let socket = TokioUnixStream::from_std(server_socket)?;
+            handle_requests_for_single_session(socket, &unix_user, &config).await?;
+            Ok(())
+        });
+
+    result?;
+
+    unsafe {
+        exit(EXIT_SUCCESS);
+    }
+}

src/core/bootstrap/authenticated_unix_socket.rs

@@ -0,0 +1,439 @@
+//! This module provides a way to authenticate a client uid to a server over a Unix socket.
+//! This is needed so that the server can trust the client's uid, which it depends on to
+//! make modifications for that user in the database. It is crucial that the server can trust
+//! that the client is the unix user it claims to be.
+//!
+//! This works by having the client respond to a challenge on a socket that is verifiably owned
+//! by the client. In more detailed steps, the following should happen:
+//!
+//! 1. Before initializing it's request, the client should open an "authentication" socket with permissions 644
+//!    and owned by the uid of the current user.
+//! 2. The client opens a request to the server on the "normal" socket where the server is listening,
+//!    In this request, the client should include the following:
+//!      - The address of it's authentication socket
+//!      - The uid of the user currently using the client
+//!      - A challenge string that has been randomly generated
+//! 3. The server validates the following:
+//!      - The address of the auth socket is valid
+//!      - The owner of the auth socket address is the same as the uid
+//! 4. Server connects to the auth socket address and receives another challenge string.
+//!    The server should close the connection after receiving the challenge string.
+//! 5. Server verifies that the challenge is the same as the one it originally received.
+//!    It responds to the client with an "Authenticated" message if the challenge matches,
+//!    or an error message if it does not.
+//! 6. Client closes the authentication socket. Normal socket is used for communication.
+//!
+//! Note that the server can at any point in the process send an error message to the client
+//! over it's initial connection, and the client should respond by closing the authentication
+//! socket, it's connection to the normal socket, and reporting the error to the user.
+//!
+//! Also note that it is essential that the client does not send any sensitive information
+//! over it's authentication socket, since it is readable by any user on the system.
+
+// TODO: rewrite this so that it can be used with a normal std::os::unix::net::UnixStream
+
+use std::os::unix::io::AsRawFd;
+use std::path::{Path, PathBuf};
+
+use async_bincode::{tokio::AsyncBincodeStream, AsyncDestination};
+use derive_more::derive::{Display, Error};
+use futures::{SinkExt, StreamExt};
+use nix::{sys::stat, unistd::Uid};
+use rand::distributions::Alphanumeric;
+use rand::Rng;
+use serde::{Deserialize, Serialize};
+use tokio::net::{UnixListener, UnixStream};
+use tokio_util::sync::CancellationToken;
+
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub enum ClientRequest {
+    Initialize {
+        uid: u32,
+        challenge: u64,
+        auth_socket: String,
+    },
+    Cancel,
+}
+
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize, Display, Error)]
+pub enum ServerResponse {
+    Authenticated,
+    ChallengeDidNotMatch,
+    ServerError(ServerError),
+}
+
+// TODO: wrap more data into the errors
+
+#[derive(Debug, Display, PartialEq, Serialize, Deserialize, Clone, Error)]
+pub enum ServerError {
+    InvalidRequest,
+    UnableToReadPermissionsFromAuthSocket,
+    CouldNotConnectToAuthSocket,
+    AuthSocketClosedEarly,
+    UidMismatch,
+    ChallengeMismatch,
+    InvalidChallenge,
+}
+
+#[derive(Debug, PartialEq, Display, Error)]
+pub enum ClientError {
+    UnableToConnectToServer,
+    UnableToOpenAuthSocket,
+    UnableToConfigureAuthSocket,
+    AuthSocketClosedEarly,
+    UnableToCloseAuthSocket,
+    AuthenticationError,
+    UnableToParseServerResponse,
+    NoServerResponse,
+    ServerError(ServerError),
+}
+
+async fn create_auth_socket(socket_addr: &PathBuf) -> Result<UnixListener, ClientError> {
+    let auth_socket =
+        UnixListener::bind(socket_addr).map_err(|_err| ClientError::UnableToOpenAuthSocket)?;
+
+    stat::fchmod(
+        auth_socket.as_raw_fd(),
+        stat::Mode::S_IRUSR | stat::Mode::S_IWUSR | stat::Mode::S_IRGRP,
+    )
+    .map_err(|_err| ClientError::UnableToConfigureAuthSocket)?;
+
+    Ok(auth_socket)
+}
+
+type ClientToServerStream<'a> =
+    AsyncBincodeStream<&'a mut UnixStream, ServerResponse, ClientRequest, AsyncDestination>;
+type ServerToClientStream<'a> =
+    AsyncBincodeStream<&'a mut UnixStream, ClientRequest, ServerResponse, AsyncDestination>;
+
+// TODO: make the challenge constant size and use socket directly, this is overkill
+type AuthStream<'a> = AsyncBincodeStream<&'a mut UnixStream, u64, u64, AsyncDestination>;
+
+// TODO: add timeout
+
+// TODO: respect $XDG_RUNTIME_DIR and $TMPDIR
+
+const AUTH_SOCKET_NAME: &str = "mysqladm-rs-cli-auth.sock";
+
+pub async fn client_authenticate(
+    normal_socket: &mut UnixStream,
+    auth_socket_dir: Option<PathBuf>,
+) -> Result<(), ClientError> {
+    let random_prefix: String = rand::thread_rng()
+        .sample_iter(&Alphanumeric)
+        .take(16)
+        .map(char::from)
+        .collect();
+
+    let socket_name = format!("{}-{}", random_prefix, AUTH_SOCKET_NAME);
+
+    let auth_socket_address = auth_socket_dir
+        .unwrap_or(std::env::temp_dir())
+        .join(socket_name);
+
+    client_authenticate_with_auth_socket_address(normal_socket, &auth_socket_address).await
+}
+
+async fn client_authenticate_with_auth_socket_address(
+    normal_socket: &mut UnixStream,
+    auth_socket_address: &PathBuf,
+) -> Result<(), ClientError> {
+    let auth_socket = create_auth_socket(auth_socket_address).await?;
+
+    let result =
+        client_authenticate_with_auth_socket(normal_socket, auth_socket, auth_socket_address).await;
+
+    std::fs::remove_file(auth_socket_address)
+        .map_err(|_err| ClientError::UnableToCloseAuthSocket)?;
+
+    result
+}
+
+async fn client_authenticate_with_auth_socket(
+    normal_socket: &mut UnixStream,
+    auth_socket: UnixListener,
+    auth_socket_address: &Path,
+) -> Result<(), ClientError> {
+    let challenge = rand::random::<u64>();
+    let uid = nix::unistd::getuid();
+
+    let mut normal_socket: ClientToServerStream =
+        AsyncBincodeStream::from(normal_socket).for_async();
+
+    let challenge_replier_cancellation_token = CancellationToken::new();
+    let challenge_replier_cancellation_token_clone = challenge_replier_cancellation_token.clone();
+    let challenge_replier_handle = tokio::spawn(async move {
+        loop {
+            tokio::select! {
+                socket = auth_socket.accept() =>
+                  {
+                  match socket {
+                      Ok((mut conn, _addr)) => {
+                          let mut stream: AuthStream = AsyncBincodeStream::from(&mut conn).for_async();
+                          stream.send(challenge).await.ok();
+                          stream.close().await.ok();
+                      }
+                      Err(_err) => return Err(ClientError::AuthSocketClosedEarly),
+                  }
+              }
+
+                _ = challenge_replier_cancellation_token_clone.cancelled() => {
+                    break Ok(());
+                }
+            }
+        }
+    });
+
+    let client_hello = ClientRequest::Initialize {
+        uid: uid.into(),
+        challenge,
+        auth_socket: auth_socket_address
+            .to_str()
+            .ok_or(ClientError::UnableToConfigureAuthSocket)?
+            .to_owned(),
+    };
+
+    normal_socket
+        .send(client_hello)
+        .await
+        .map_err(|err| match *err {
+            bincode::ErrorKind::Io(_err) => ClientError::UnableToConnectToServer,
+            _ => ClientError::NoServerResponse,
+        })?;
+
+    match normal_socket.next().await {
+        Some(Ok(ServerResponse::Authenticated)) => {}
+        Some(Ok(ServerResponse::ChallengeDidNotMatch)) => {
+            return Err(ClientError::AuthenticationError)
+        }
+        Some(Ok(ServerResponse::ServerError(err))) => return Err(ClientError::ServerError(err)),
+        Some(Err(err)) => match *err {
+            bincode::ErrorKind::Io(_err) => return Err(ClientError::NoServerResponse),
+            _ => return Err(ClientError::UnableToParseServerResponse),
+        },
+        None => return Err(ClientError::NoServerResponse),
+    }
+
+    challenge_replier_cancellation_token.cancel();
+    challenge_replier_handle.await.ok();
+
+    Ok(())
+}
+
+macro_rules! report_server_error_and_return {
+    ($normal_socket:expr, $err:expr) => {{
+        $normal_socket
+            .send(ServerResponse::ServerError($err))
+            .await
+            .ok();
+        return Err($err);
+    }};
+}
+
+pub async fn server_authenticate(normal_socket: &mut UnixStream) -> Result<Uid, ServerError> {
+    _server_authenticate(normal_socket, None).await
+}
+
+pub async fn _server_authenticate(
+    normal_socket: &mut UnixStream,
+    unix_user_uid: Option<u32>,
+) -> Result<Uid, ServerError> {
+    let mut normal_socket: ServerToClientStream =
+        AsyncBincodeStream::from(normal_socket).for_async();
+
+    let (uid, challenge, auth_socket) = match normal_socket.next().await {
+        Some(Ok(ClientRequest::Initialize {
+            uid,
+            challenge,
+            auth_socket,
+        })) => (uid, challenge, auth_socket),
+        // TODO: more granular errros
+        _ => report_server_error_and_return!(normal_socket, ServerError::InvalidRequest),
+    };
+
+    let auth_socket_uid = match unix_user_uid {
+        Some(uid) => uid,
+        None => match stat::stat(auth_socket.as_str()) {
+            Ok(stat) => stat.st_uid,
+            Err(_err) => report_server_error_and_return!(
+                normal_socket,
+                ServerError::UnableToReadPermissionsFromAuthSocket
+            ),
+        },
+    };
+
+    if uid != auth_socket_uid {
+        report_server_error_and_return!(normal_socket, ServerError::UidMismatch);
+    }
+
+    let mut authenticated_unix_socket = match UnixStream::connect(auth_socket).await {
+        Ok(socket) => socket,
+        Err(_err) => {
+            report_server_error_and_return!(normal_socket, ServerError::CouldNotConnectToAuthSocket)
+        }
+    };
+    let mut authenticated_unix_socket: AuthStream =
+        AsyncBincodeStream::from(&mut authenticated_unix_socket).for_async();
+
+    let challenge_2 = match authenticated_unix_socket.next().await {
+        Some(Ok(challenge)) => challenge,
+        Some(Err(_)) => {
+            report_server_error_and_return!(normal_socket, ServerError::InvalidChallenge)
+        }
+        None => report_server_error_and_return!(normal_socket, ServerError::AuthSocketClosedEarly),
+    };
+
+    authenticated_unix_socket.close().await.ok();
+
+    if challenge != challenge_2 {
+        normal_socket
+            .send(ServerResponse::ChallengeDidNotMatch)
+            .await
+            .ok();
+        return Err(ServerError::ChallengeMismatch);
+    }
+
+    normal_socket.send(ServerResponse::Authenticated).await.ok();
+
+    Ok(Uid::from_raw(uid))
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    use std::time::Duration;
+    use tokio::time::sleep;
+
+    #[tokio::test]
+    async fn test_valid_authentication() {
+        let (mut client, mut server) = UnixStream::pair().unwrap();
+
+        let client_handle =
+            tokio::spawn(async move { client_authenticate(&mut client, None).await });
+
+        let server_handle = tokio::spawn(async move { server_authenticate(&mut server).await });
+
+        client_handle.await.unwrap().unwrap();
+        server_handle.await.unwrap().unwrap();
+    }
+
+    #[tokio::test]
+    async fn test_ensure_auth_socket_does_not_exist() {
+        let (mut client, mut server) = UnixStream::pair().unwrap();
+
+        let client_handle = tokio::spawn(async move {
+            client_authenticate_with_auth_socket_address(
+                &mut client,
+                &PathBuf::from("/tmp/test_auth_socket_does_not_exist.sock"),
+            )
+            .await
+        });
+
+        let server_handle = tokio::spawn(async move { server_authenticate(&mut server).await });
+
+        client_handle.await.unwrap().unwrap();
+        server_handle.await.unwrap().unwrap();
+    }
+
+    #[tokio::test]
+    async fn test_uid_mismatch() {
+        let (mut client, mut server) = UnixStream::pair().unwrap();
+
+        let client_handle = tokio::spawn(async move {
+            let err = client_authenticate(&mut client, None).await;
+            assert_eq!(err, Err(ClientError::ServerError(ServerError::UidMismatch)));
+        });
+
+        let server_handle = tokio::spawn(async move {
+            let uid: u32 = nix::unistd::getuid().into();
+            let err = _server_authenticate(&mut server, Some(uid + 1)).await;
+            assert_eq!(err, Err(ServerError::UidMismatch));
+        });
+
+        client_handle.await.unwrap();
+        server_handle.await.unwrap();
+    }
+
+    #[tokio::test]
+    async fn test_snooping_connection() {
+        let (mut client, mut server) = UnixStream::pair().unwrap();
+
+        let socket_path = std::env::temp_dir().join("socket_to_snoop.sock");
+        let socket_path_clone = socket_path.clone();
+        let client_handle = tokio::spawn(async move {
+            client_authenticate_with_auth_socket_address(&mut client, &socket_path_clone).await
+        });
+
+        for i in 0..100 {
+            if socket_path.exists() {
+                break;
+            }
+            sleep(Duration::from_millis(10)).await;
+
+            if i == 99 {
+                panic!("Socket not created after 1 second, assuming test failure");
+            }
+        }
+
+        let mut snooper = UnixStream::connect(socket_path.clone()).await.unwrap();
+        let mut snooper: AuthStream = AsyncBincodeStream::from(&mut snooper).for_async();
+        let message = snooper.next().await.unwrap().unwrap();
+
+        let mut other_snooper = UnixStream::connect(socket_path.clone()).await.unwrap();
+        let mut other_snooper: AuthStream =
+            AsyncBincodeStream::from(&mut other_snooper).for_async();
+        let other_message = other_snooper.next().await.unwrap().unwrap();
+
+        assert_eq!(message, other_message);
+
+        let third_snooper_handle = tokio::spawn(async move {
+            let mut third_snooper = UnixStream::connect(socket_path.clone()).await.unwrap();
+            let mut third_snooper: AuthStream =
+                AsyncBincodeStream::from(&mut third_snooper).for_async();
+            // NOTE: Should hang
+            third_snooper.send(1234).await.unwrap()
+        });
+
+        sleep(Duration::from_millis(10)).await;
+
+        let server_handle = tokio::spawn(async move { server_authenticate(&mut server).await });
+
+        client_handle.await.unwrap().unwrap();
+        server_handle.await.unwrap().unwrap();
+
+        third_snooper_handle.abort();
+    }
+
+    #[tokio::test]
+    async fn test_dead_server() {
+        let (mut client, server) = UnixStream::pair().unwrap();
+        std::mem::drop(server);
+
+        let client_handle = tokio::spawn(async move {
+            let err = client_authenticate(&mut client, None).await;
+            assert_eq!(err, Err(ClientError::UnableToConnectToServer));
+        });
+
+        client_handle.await.unwrap();
+    }
+
+    #[tokio::test]
+    async fn test_no_response_from_server() {
+        let (mut client, server) = UnixStream::pair().unwrap();
+
+        let client_handle = tokio::spawn(async move {
+            let err = client_authenticate(&mut client, None).await;
+            assert_eq!(err, Err(ClientError::NoServerResponse));
+        });
+
+        sleep(Duration::from_millis(200)).await;
+
+        std::mem::drop(server);
+
+        client_handle.await.unwrap();
+    }
+
+    // TODO: Test challenge mismatch
+    // TODO: Test invoking server with junk data
+}

src/core/common.rs

@@ -1,56 +1,32 @@
 use anyhow::Context;
-use indoc::indoc;
-use itertools::Itertools;
-use nix::unistd::{getuid, Group, User};
-use sqlx::{Connection, MySqlConnection};
+use nix::unistd::{Group as LibcGroup, User as LibcUser};
 
 #[cfg(not(target_os = "macos"))]
 use std::ffi::CString;
 
-/// Report the result status of a command.
-/// This is used to display a status message to the user.
-pub enum CommandStatus {
-    /// The command was successful,
-    /// and made modification to the database.
-    SuccessfullyModified,
+pub const DEFAULT_CONFIG_PATH: &str = "/etc/mysqladm/config.toml";
+pub const DEFAULT_SOCKET_PATH: &str = "/run/mysqladm/mysqladm.sock";
 
-    /// The command was mostly successful,
-    /// and modifications have been made to the database.
-    /// However, some of the requested modifications failed.
-    PartiallySuccessfullyModified,
-
-    /// The command was successful,
-    /// but no modifications were needed.
-    NoModificationsNeeded,
-
-    /// The command was successful,
-    /// and made no modification to the database.
-    NoModificationsIntended,
-
-    /// The command was cancelled, either through a dialog or a signal.
-    /// No modifications have been made to the database.
-    Cancelled,
+pub struct UnixUser {
+    pub username: String,
+    pub groups: Vec<String>,
 }
 
-pub fn get_current_unix_user() -> anyhow::Result<User> {
-    User::from_uid(getuid())
-        .context("Failed to look up your UNIX username")
-        .and_then(|u| u.ok_or(anyhow::anyhow!("Failed to look up your UNIX username")))
-}
+// TODO: these functions are somewhat critical, and should have integration tests
 
 #[cfg(target_os = "macos")]
-pub fn get_unix_groups(_user: &User) -> anyhow::Result<Vec<Group>> {
+fn get_unix_groups(_user: &LibcUser) -> anyhow::Result<Vec<LibcGroup>> {
     // Return an empty list on macOS since there is no `getgrouplist` function
     Ok(vec![])
 }
 
 #[cfg(not(target_os = "macos"))]
-pub fn get_unix_groups(user: &User) -> anyhow::Result<Vec<Group>> {
+fn get_unix_groups(user: &LibcUser) -> anyhow::Result<Vec<LibcGroup>> {
     let user_cstr =
         CString::new(user.name.as_bytes()).context("Failed to convert username to CStr")?;
     let groups = nix::unistd::getgrouplist(&user_cstr, user.gid)?
         .iter()
-        .filter_map(|gid| match Group::from_gid(*gid) {
+        .filter_map(|gid| match LibcGroup::from_gid(*gid) {
             Ok(Some(group)) => Some(group),
             Ok(None) => None,
             Err(e) => {
@@ -62,211 +38,32 @@ pub fn get_unix_groups(user: &User) -> anyhow::Result<Vec<Group>> {
                 None
             }
         })
-        .collect::<Vec<Group>>();
+        .collect::<Vec<LibcGroup>>();
 
     Ok(groups)
 }
 
-/// This function creates a regex that matches items (users, databases)
-/// that belong to the user or any of the user's groups.
-pub fn create_user_group_matching_regex(user: &User) -> String {
-    let groups = get_unix_groups(user).unwrap_or_default();
+impl UnixUser {
+    pub fn from_uid(uid: u32) -> anyhow::Result<Self> {
+        let libc_uid = nix::unistd::Uid::from_raw(uid);
+        let libc_user = LibcUser::from_uid(libc_uid)
+            .context("Failed to look up your UNIX username")?
+            .ok_or(anyhow::anyhow!("Failed to look up your UNIX username"))?;
 
-    if groups.is_empty() {
-        format!("{}(_.+)?", user.name)
-    } else {
-        format!(
-            "({}|{})(_.+)?",
-            user.name,
-            groups
-                .iter()
-                .map(|g| g.name.as_str())
-                .collect::<Vec<_>>()
-                .join("|")
-        )
-    }
-}
+        let groups = get_unix_groups(&libc_user)?;
 
-/// This enum is used to differentiate between database and user operations.
-/// Their output are very similar, but there are slight differences in the words used.
-#[derive(Debug, PartialEq, Eq, Clone, Copy)]
-pub enum DbOrUser {
-    Database,
-    User,
-}
-
-impl DbOrUser {
-    pub fn lowercased(&self) -> String {
-        match self {
-            DbOrUser::Database => "database".to_string(),
-            DbOrUser::User => "user".to_string(),
-        }
+        Ok(UnixUser {
+            username: libc_user.name,
+            groups: groups.iter().map(|g| g.name.clone()).collect(),
+        })
     }
 
-    pub fn capitalized(&self) -> String {
-        match self {
-            DbOrUser::Database => "Database".to_string(),
-            DbOrUser::User => "User".to_string(),
-        }
+    pub fn from_enviroment() -> anyhow::Result<Self> {
+        let libc_uid = nix::unistd::getuid();
+        UnixUser::from_uid(libc_uid.as_raw())
     }
 }
 
-#[derive(Debug, PartialEq, Eq)]
-pub enum NameValidationResult {
-    Valid,
-    EmptyString,
-    InvalidCharacters,
-    TooLong,
-}
-
-pub fn validate_name(name: &str) -> NameValidationResult {
-    if name.is_empty() {
-        NameValidationResult::EmptyString
-    } else if name.len() > 64 {
-        NameValidationResult::TooLong
-    } else if !name
-        .chars()
-        .all(|c| c.is_ascii_alphanumeric() || c == '_' || c == '-')
-    {
-        NameValidationResult::InvalidCharacters
-    } else {
-        NameValidationResult::Valid
-    }
-}
-
-pub fn validate_name_or_error(name: &str, db_or_user: DbOrUser) -> anyhow::Result<()> {
-    match validate_name(name) {
-        NameValidationResult::Valid => Ok(()),
-        NameValidationResult::EmptyString => {
-            anyhow::bail!("{} name cannot be empty.", db_or_user.capitalized())
-        }
-        NameValidationResult::TooLong => anyhow::bail!(
-            "{} is too long. Maximum length is 64 characters.",
-            db_or_user.capitalized()
-        ),
-        NameValidationResult::InvalidCharacters => anyhow::bail!(
-            indoc! {r#"
-              Invalid characters in {} name: '{}'
-
-              Only A-Z, a-z, 0-9, _ (underscore) and - (dash) are permitted.
-            "#},
-            db_or_user.lowercased(),
-            name
-        ),
-    }
-}
-
-#[derive(Debug, PartialEq, Eq)]
-pub enum OwnerValidationResult {
-    // The name is valid and matches one of the given prefixes
-    Match,
-
-    // The name is valid, but none of the given prefixes matched the name
-    NoMatch,
-
-    // The name is empty, which is invalid
-    StringEmpty,
-
-    // The name is in the format "_<postfix>", which is invalid
-    MissingPrefix,
-
-    // The name is in the format "<prefix>_", which is invalid
-    MissingPostfix,
-}
-
-/// Core logic for validating the ownership of a database name.
-/// This function checks if the given name matches any of the given prefixes.
-/// These prefixes will in most cases be the user's unix username and any
-/// unix groups the user is a member of.
-pub fn validate_ownership_by_prefixes(name: &str, prefixes: &[String]) -> OwnerValidationResult {
-    if name.is_empty() {
-        return OwnerValidationResult::StringEmpty;
-    }
-
-    if name.starts_with('_') {
-        return OwnerValidationResult::MissingPrefix;
-    }
-
-    let (prefix, _) = match name.split_once('_') {
-        Some(pair) => pair,
-        None => return OwnerValidationResult::MissingPostfix,
-    };
-
-    if prefixes.iter().any(|g| g == prefix) {
-        OwnerValidationResult::Match
-    } else {
-        OwnerValidationResult::NoMatch
-    }
-}
-
-/// Validate the ownership of a database name or database user name.
-/// This function takes the name of a database or user and a unix user,
-/// for which it fetches the user's groups. It then checks if the name
-/// is prefixed with the user's username or any of the user's groups.
-pub fn validate_ownership_or_error<'a>(
-    name: &'a str,
-    user: &User,
-    db_or_user: DbOrUser,
-) -> anyhow::Result<&'a str> {
-    let user_groups = get_unix_groups(user)?;
-    let prefixes = std::iter::once(user.name.clone())
-        .chain(user_groups.iter().map(|g| g.name.clone()))
-        .collect::<Vec<String>>();
-
-    match validate_ownership_by_prefixes(name, &prefixes) {
-        OwnerValidationResult::Match => Ok(name),
-        OwnerValidationResult::NoMatch => {
-            anyhow::bail!(
-                indoc! {r#"
-                  Invalid {} name prefix: '{}' does not match your username or any of your groups.
-                  Are you sure you are allowed to create {} names with this prefix?
-
-                  Allowed prefixes:
-                    - {}
-                  {}
-                "#},
-                db_or_user.lowercased(),
-                name,
-                db_or_user.lowercased(),
-                user.name,
-                user_groups
-                    .iter()
-                    .filter(|g| g.name != user.name)
-                    .map(|g| format!("  - {}", g.name))
-                    .sorted()
-                    .join("\n"),
-            );
-        }
-        _ => anyhow::bail!(
-            "'{}' is not a valid {} name.",
-            name,
-            db_or_user.lowercased()
-        ),
-    }
-}
-
-/// Gracefully close a MySQL connection.
-pub async fn close_database_connection(connection: MySqlConnection) {
-    if let Err(e) = connection
-        .close()
-        .await
-        .context("Failed to close connection properly")
-    {
-        eprintln!("{}", e);
-        eprintln!("Ignoring...");
-    }
-}
-
-#[inline]
-pub fn quote_literal(s: &str) -> String {
-    format!("'{}'", s.replace('\'', r"\'"))
-}
-
-#[inline]
-pub fn quote_identifier(s: &str) -> String {
-    format!("`{}`", s.replace('`', r"\`"))
-}
-
 #[inline]
 pub(crate) fn yn(b: bool) -> &'static str {
     if b {
@@ -303,94 +100,4 @@ mod test {
         assert_eq!(rev_yn("n"), Some(false));
         assert_eq!(rev_yn("X"), None);
     }
-
-    #[test]
-    fn test_quote_literal() {
-        let payload = "' OR 1=1 --";
-        assert_eq!(quote_literal(payload), r#"'\' OR 1=1 --'"#);
-    }
-
-    #[test]
-    fn test_quote_identifier() {
-        let payload = "` OR 1=1 --";
-        assert_eq!(quote_identifier(payload), r#"`\` OR 1=1 --`"#);
-    }
-
-    #[test]
-    fn test_validate_name() {
-        assert_eq!(validate_name(""), NameValidationResult::EmptyString);
-        assert_eq!(
-            validate_name("abcdefghijklmnopqrstuvwxyz"),
-            NameValidationResult::Valid
-        );
-        assert_eq!(
-            validate_name("ABCDEFGHIJKLMNOPQRSTUVWXYZ"),
-            NameValidationResult::Valid
-        );
-        assert_eq!(validate_name("0123456789_-"), NameValidationResult::Valid);
-
-        for c in "\n\t\r !@#$%^&*()+=[]{}|;:,.<>?/".chars() {
-            assert_eq!(
-                validate_name(&c.to_string()),
-                NameValidationResult::InvalidCharacters
-            );
-        }
-
-        assert_eq!(validate_name(&"a".repeat(64)), NameValidationResult::Valid);
-
-        assert_eq!(
-            validate_name(&"a".repeat(65)),
-            NameValidationResult::TooLong
-        );
-    }
-
-    #[test]
-    fn test_validate_owner_by_prefixes() {
-        let prefixes = vec!["user".to_string(), "group".to_string()];
-
-        assert_eq!(
-            validate_ownership_by_prefixes("", &prefixes),
-            OwnerValidationResult::StringEmpty
-        );
-
-        assert_eq!(
-            validate_ownership_by_prefixes("user", &prefixes),
-            OwnerValidationResult::MissingPostfix
-        );
-        assert_eq!(
-            validate_ownership_by_prefixes("something", &prefixes),
-            OwnerValidationResult::MissingPostfix
-        );
-        assert_eq!(
-            validate_ownership_by_prefixes("user-testdb", &prefixes),
-            OwnerValidationResult::MissingPostfix
-        );
-
-        assert_eq!(
-            validate_ownership_by_prefixes("_testdb", &prefixes),
-            OwnerValidationResult::MissingPrefix
-        );
-
-        assert_eq!(
-            validate_ownership_by_prefixes("user_testdb", &prefixes),
-            OwnerValidationResult::Match
-        );
-        assert_eq!(
-            validate_ownership_by_prefixes("group_testdb", &prefixes),
-            OwnerValidationResult::Match
-        );
-        assert_eq!(
-            validate_ownership_by_prefixes("group_test_db", &prefixes),
-            OwnerValidationResult::Match
-        );
-        assert_eq!(
-            validate_ownership_by_prefixes("group_test-db", &prefixes),
-            OwnerValidationResult::Match
-        );
-
-        assert_eq!(
-            validate_ownership_by_prefixes("nonexistent_testdb", &prefixes),
-            OwnerValidationResult::NoMatch
-        );
-    }
 }

src/core/config.rs

@@ -1,121 +0,0 @@
-use std::{fs, path::PathBuf, time::Duration};
-
-use anyhow::{anyhow, Context};
-use clap::Parser;
-use serde::{Deserialize, Serialize};
-use sqlx::{mysql::MySqlConnectOptions, ConnectOptions, MySqlConnection};
-
-// NOTE: this might look empty now, and the extra wrapping for the mysql
-//       config seems unnecessary, but it will be useful later when we
-//       add more configuration options.
-#[derive(Debug, Clone, Deserialize, Serialize)]
-pub struct Config {
-    pub mysql: MysqlConfig,
-}
-
-#[derive(Debug, Clone, Deserialize, Serialize)]
-#[serde(rename = "mysql")]
-pub struct MysqlConfig {
-    pub host: String,
-    pub port: Option<u16>,
-    pub username: String,
-    pub password: String,
-    pub timeout: Option<u64>,
-}
-
-const DEFAULT_PORT: u16 = 3306;
-const DEFAULT_TIMEOUT: u64 = 2;
-
-#[derive(Parser)]
-pub struct GlobalConfigArgs {
-    /// Path to the configuration file.
-    #[arg(
-        short,
-        long,
-        value_name = "PATH",
-        global = true,
-        hide_short_help = true,
-        default_value = "/etc/mysqladm/config.toml"
-    )]
-    config_file: String,
-
-    /// Hostname of the MySQL server.
-    #[arg(long, value_name = "HOST", global = true, hide_short_help = true)]
-    mysql_host: Option<String>,
-
-    /// Port of the MySQL server.
-    #[arg(long, value_name = "PORT", global = true, hide_short_help = true)]
-    mysql_port: Option<u16>,
-
-    /// Username to use for the MySQL connection.
-    #[arg(long, value_name = "USER", global = true, hide_short_help = true)]
-    mysql_user: Option<String>,
-
-    /// Path to a file containing the MySQL password.
-    #[arg(long, value_name = "PATH", global = true, hide_short_help = true)]
-    mysql_password_file: Option<String>,
-
-    /// Seconds to wait for the MySQL connection to be established.
-    #[arg(long, value_name = "SECONDS", global = true, hide_short_help = true)]
-    mysql_connect_timeout: Option<u64>,
-}
-
-/// Use the arguments and whichever configuration file which might or might not
-/// be found and default values to determine the configuration for the program.
-pub fn get_config(args: GlobalConfigArgs) -> anyhow::Result<Config> {
-    let config_path = PathBuf::from(args.config_file);
-
-    let config: Config = fs::read_to_string(&config_path)
-        .context(format!(
-            "Failed to read config file from {:?}",
-            &config_path
-        ))
-        .and_then(|c| toml::from_str(&c).context("Failed to parse config file"))
-        .context(format!(
-            "Failed to parse config file from {:?}",
-            &config_path
-        ))?;
-
-    let mysql = &config.mysql;
-
-    let password = if let Some(path) = args.mysql_password_file {
-        fs::read_to_string(path)
-            .context("Failed to read MySQL password file")
-            .map(|s| s.trim().to_owned())?
-    } else {
-        mysql.password.to_owned()
-    };
-
-    let mysql_config = MysqlConfig {
-        host: args.mysql_host.unwrap_or(mysql.host.to_owned()),
-        port: args.mysql_port.or(mysql.port),
-        username: args.mysql_user.unwrap_or(mysql.username.to_owned()),
-        password,
-        timeout: args.mysql_connect_timeout.or(mysql.timeout),
-    };
-
-    Ok(Config {
-        mysql: mysql_config,
-    })
-}
-
-/// Use the provided configuration to establish a connection to a MySQL server.
-pub async fn create_mysql_connection_from_config(
-    config: MysqlConfig,
-) -> anyhow::Result<MySqlConnection> {
-    match tokio::time::timeout(
-        Duration::from_secs(config.timeout.unwrap_or(DEFAULT_TIMEOUT)),
-        MySqlConnectOptions::new()
-            .host(&config.host)
-            .username(&config.username)
-            .password(&config.password)
-            .port(config.port.unwrap_or(DEFAULT_PORT))
-            .database("mysql")
-            .connect(),
-    )
-    .await
-    {
-        Ok(connection) => connection.context("Failed to connect to MySQL"),
-        Err(_) => Err(anyhow!("Timed out after 2 seconds")).context("Failed to connect to MySQL"),
-    }
-}

src/core/database_operations.rs

@@ -1,120 +0,0 @@
-use anyhow::Context;
-use indoc::formatdoc;
-use itertools::Itertools;
-use nix::unistd::User;
-use sqlx::{prelude::*, MySqlConnection};
-
-use crate::core::{
-    common::{
-        create_user_group_matching_regex, get_current_unix_user, quote_identifier,
-        validate_name_or_error, validate_ownership_or_error, DbOrUser,
-    },
-    database_privilege_operations::DATABASE_PRIVILEGE_FIELDS,
-};
-
-pub async fn create_database(name: &str, connection: &mut MySqlConnection) -> anyhow::Result<()> {
-    let user = get_current_unix_user()?;
-    validate_database_name(name, &user)?;
-
-    // NOTE: see the note about SQL injections in `validate_owner_of_database_name`
-    sqlx::query(&format!("CREATE DATABASE {}", quote_identifier(name)))
-        .execute(connection)
-        .await
-        .map_err(|e| {
-            if e.to_string().contains("database exists") {
-                anyhow::anyhow!("Database '{}' already exists", name)
-            } else {
-                e.into()
-            }
-        })?;
-
-    Ok(())
-}
-
-pub async fn drop_database(name: &str, connection: &mut MySqlConnection) -> anyhow::Result<()> {
-    let user = get_current_unix_user()?;
-    validate_database_name(name, &user)?;
-
-    // NOTE: see the note about SQL injections in `validate_owner_of_database_name`
-    sqlx::query(&format!("DROP DATABASE {}", quote_identifier(name)))
-        .execute(connection)
-        .await
-        .map_err(|e| {
-            if e.to_string().contains("doesn't exist") {
-                anyhow::anyhow!("Database '{}' does not exist", name)
-            } else {
-                e.into()
-            }
-        })?;
-
-    Ok(())
-}
-
-pub async fn get_database_list(connection: &mut MySqlConnection) -> anyhow::Result<Vec<String>> {
-    let unix_user = get_current_unix_user()?;
-
-    let databases: Vec<String> = sqlx::query(
-        r#"
-          SELECT `SCHEMA_NAME` AS `database`
-          FROM `information_schema`.`SCHEMATA`
-          WHERE `SCHEMA_NAME` NOT IN ('information_schema', 'performance_schema', 'mysql', 'sys')
-            AND `SCHEMA_NAME` REGEXP ?
-        "#,
-    )
-    .bind(create_user_group_matching_regex(&unix_user))
-    .fetch_all(connection)
-    .await
-    .and_then(|row| {
-        row.into_iter()
-            .map(|row| row.try_get::<String, _>("database"))
-            .collect::<Result<_, _>>()
-    })
-    .context(format!(
-        "Failed to get databases for user '{}'",
-        unix_user.name
-    ))?;
-
-    Ok(databases)
-}
-
-pub async fn get_databases_where_user_has_privileges(
-    username: &str,
-    connection: &mut MySqlConnection,
-) -> anyhow::Result<Vec<String>> {
-    let result = sqlx::query(
-        formatdoc!(
-            r#"
-            SELECT `db` AS `database`
-            FROM `db`
-            WHERE `user` = ?
-              AND ({})
-        "#,
-            DATABASE_PRIVILEGE_FIELDS
-                .iter()
-                .map(|field| format!("`{}` = 'Y'", field))
-                .join(" OR "),
-        )
-        .as_str(),
-    )
-    .bind(username)
-    .fetch_all(connection)
-    .await?
-    .into_iter()
-    .map(|databases| databases.try_get::<String, _>("database").unwrap())
-    .collect();
-
-    Ok(result)
-}
-
-/// NOTE: It is very critical that this function validates the database name
-///       properly. MySQL does not seem to allow for prepared statements, binding
-///       the database name as a parameter to the query. This means that we have
-///       to validate the database name ourselves to prevent SQL injection.
-pub fn validate_database_name(name: &str, user: &User) -> anyhow::Result<()> {
-    validate_name_or_error(name, DbOrUser::Database)
-        .context(format!("Invalid database name: '{}'", name))?;
-    validate_ownership_or_error(name, user, DbOrUser::Database)
-        .context(format!("Invalid database name: '{}'", name))?;
-
-    Ok(())
-}

src/core/database_privileges.rs

@@ -1,52 +1,16 @@
-//! Database privilege operations
-//!
-//! This module contains functions for querying, modifying,
-//! displaying and comparing database privileges.
-//!
-//! A lot of the complexity comes from two core components:
-//!
-//! - The privilege editor that needs to be able to print
-//!   an editable table of privileges and reparse the content
-//!   after the user has made manual changes.
-//!
-//! - The comparison functionality that tells the user what
-//!   changes will be made when applying a set of changes
-//!   to the list of database privileges.
-
-use std::collections::{BTreeSet, HashMap};
-
 use anyhow::{anyhow, Context};
-use indoc::indoc;
 use itertools::Itertools;
 use prettytable::Table;
 use serde::{Deserialize, Serialize};
-use sqlx::{mysql::MySqlRow, prelude::*, MySqlConnection};
-
-use crate::core::{
-    common::{
-        create_user_group_matching_regex, get_current_unix_user, quote_identifier, rev_yn, yn,
-    },
-    database_operations::validate_database_name,
+use std::{
+    cmp::max,
+    collections::{BTreeSet, HashMap},
 };
 
-/// This is the list of fields that are used to fetch the db + user + privileges
-/// from the `db` table in the database. If you need to add or remove privilege
-/// fields, this is a good place to start.
-pub const DATABASE_PRIVILEGE_FIELDS: [&str; 13] = [
-    "db",
-    "user",
-    "select_priv",
-    "insert_priv",
-    "update_priv",
-    "delete_priv",
-    "create_priv",
-    "drop_priv",
-    "alter_priv",
-    "index_priv",
-    "create_tmp_table_priv",
-    "lock_tables_priv",
-    "references_priv",
-];
+use super::common::{rev_yn, yn};
+use crate::server::sql::database_privilege_operations::{
+    DatabasePrivilegeRow, DATABASE_PRIVILEGE_FIELDS,
+};
 
 pub fn db_priv_field_human_readable_name(name: &str) -> String {
     match name {
@@ -67,162 +31,24 @@ pub fn db_priv_field_human_readable_name(name: &str) -> String {
     }
 }
 
-/// This struct represents the set of privileges for a single user on a single database.
-#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize, PartialOrd, Ord)]
-pub struct DatabasePrivilegeRow {
-    pub db: String,
-    pub user: String,
-    pub select_priv: bool,
-    pub insert_priv: bool,
-    pub update_priv: bool,
-    pub delete_priv: bool,
-    pub create_priv: bool,
-    pub drop_priv: bool,
-    pub alter_priv: bool,
-    pub index_priv: bool,
-    pub create_tmp_table_priv: bool,
-    pub lock_tables_priv: bool,
-    pub references_priv: bool,
-}
+pub fn diff(row1: &DatabasePrivilegeRow, row2: &DatabasePrivilegeRow) -> DatabasePrivilegeRowDiff {
+    debug_assert!(row1.db == row2.db && row1.user == row2.user);
 
-impl DatabasePrivilegeRow {
-    pub fn empty(db: &str, user: &str) -> Self {
-        Self {
-            db: db.to_owned(),
-            user: user.to_owned(),
-            select_priv: false,
-            insert_priv: false,
-            update_priv: false,
-            delete_priv: false,
-            create_priv: false,
-            drop_priv: false,
-            alter_priv: false,
-            index_priv: false,
-            create_tmp_table_priv: false,
-            lock_tables_priv: false,
-            references_priv: false,
-        }
+    DatabasePrivilegeRowDiff {
+        db: row1.db.clone(),
+        user: row1.user.clone(),
+        diff: DATABASE_PRIVILEGE_FIELDS
+            .into_iter()
+            .skip(2)
+            .filter_map(|field| {
+                DatabasePrivilegeChange::new(
+                    row1.get_privilege_by_name(field),
+                    row2.get_privilege_by_name(field),
+                    field,
+                )
+            })
+            .collect(),
     }
-
-    pub fn get_privilege_by_name(&self, name: &str) -> bool {
-        match name {
-            "select_priv" => self.select_priv,
-            "insert_priv" => self.insert_priv,
-            "update_priv" => self.update_priv,
-            "delete_priv" => self.delete_priv,
-            "create_priv" => self.create_priv,
-            "drop_priv" => self.drop_priv,
-            "alter_priv" => self.alter_priv,
-            "index_priv" => self.index_priv,
-            "create_tmp_table_priv" => self.create_tmp_table_priv,
-            "lock_tables_priv" => self.lock_tables_priv,
-            "references_priv" => self.references_priv,
-            _ => false,
-        }
-    }
-
-    pub fn diff(&self, other: &DatabasePrivilegeRow) -> DatabasePrivilegeRowDiff {
-        debug_assert!(self.db == other.db && self.user == other.user);
-
-        DatabasePrivilegeRowDiff {
-            db: self.db.clone(),
-            user: self.user.clone(),
-            diff: DATABASE_PRIVILEGE_FIELDS
-                .into_iter()
-                .skip(2)
-                .filter_map(|field| {
-                    DatabasePrivilegeChange::new(
-                        self.get_privilege_by_name(field),
-                        other.get_privilege_by_name(field),
-                        field,
-                    )
-                })
-                .collect(),
-        }
-    }
-}
-
-#[inline]
-fn get_mysql_row_priv_field(row: &MySqlRow, position: usize) -> Result<bool, sqlx::Error> {
-    let field = DATABASE_PRIVILEGE_FIELDS[position];
-    let value = row.try_get(position)?;
-    match rev_yn(value) {
-        Some(val) => Ok(val),
-        _ => {
-            log::warn!(r#"Invalid value for privilege "{}": '{}'"#, field, value);
-            Ok(false)
-        }
-    }
-}
-
-impl FromRow<'_, MySqlRow> for DatabasePrivilegeRow {
-    fn from_row(row: &MySqlRow) -> Result<Self, sqlx::Error> {
-        Ok(Self {
-            db: row.try_get("db")?,
-            user: row.try_get("user")?,
-            select_priv: get_mysql_row_priv_field(row, 2)?,
-            insert_priv: get_mysql_row_priv_field(row, 3)?,
-            update_priv: get_mysql_row_priv_field(row, 4)?,
-            delete_priv: get_mysql_row_priv_field(row, 5)?,
-            create_priv: get_mysql_row_priv_field(row, 6)?,
-            drop_priv: get_mysql_row_priv_field(row, 7)?,
-            alter_priv: get_mysql_row_priv_field(row, 8)?,
-            index_priv: get_mysql_row_priv_field(row, 9)?,
-            create_tmp_table_priv: get_mysql_row_priv_field(row, 10)?,
-            lock_tables_priv: get_mysql_row_priv_field(row, 11)?,
-            references_priv: get_mysql_row_priv_field(row, 12)?,
-        })
-    }
-}
-
-/// Get all users + privileges for a single database.
-pub async fn get_database_privileges(
-    database_name: &str,
-    connection: &mut MySqlConnection,
-) -> anyhow::Result<Vec<DatabasePrivilegeRow>> {
-    let unix_user = get_current_unix_user()?;
-    validate_database_name(database_name, &unix_user)?;
-
-    let result = sqlx::query_as::<_, DatabasePrivilegeRow>(&format!(
-        "SELECT {} FROM `db` WHERE `db` = ?",
-        DATABASE_PRIVILEGE_FIELDS
-            .iter()
-            .map(|field| quote_identifier(field))
-            .join(","),
-    ))
-    .bind(database_name)
-    .fetch_all(connection)
-    .await
-    .context("Failed to show database")?;
-
-    Ok(result)
-}
-
-/// Get all database + user + privileges pairs that are owned by the current user.
-pub async fn get_all_database_privileges(
-    connection: &mut MySqlConnection,
-) -> anyhow::Result<Vec<DatabasePrivilegeRow>> {
-    let unix_user = get_current_unix_user()?;
-
-    let result = sqlx::query_as::<_, DatabasePrivilegeRow>(&format!(
-        indoc! {r#"
-          SELECT {} FROM `db` WHERE `db` IN
-          (SELECT DISTINCT `SCHEMA_NAME` AS `database`
-            FROM `information_schema`.`SCHEMATA`
-            WHERE `SCHEMA_NAME` NOT IN ('information_schema', 'performance_schema', 'mysql', 'sys')
-              AND `SCHEMA_NAME` REGEXP ?)
-        "#},
-        DATABASE_PRIVILEGE_FIELDS
-            .iter()
-            .map(|field| format!("`{field}`"))
-            .join(","),
-    ))
-    .bind(create_user_group_matching_regex(&unix_user))
-    .fetch_all(connection)
-    .await
-    .context("Failed to show databases")?;
-
-    Ok(result)
 }
 
 /*************************/
@@ -340,17 +166,23 @@ pub fn generate_editor_content_from_privilege_data(
     //       editor will be the example user and example db name.
     //       Hence, it's put as the fallback value, despite not really
     //       being a "fallback" in the normal sense.
-    let longest_username = privilege_data
-        .iter()
-        .map(|p| p.user.len())
-        .max()
-        .unwrap_or(example_user.len());
+    let longest_username = max(
+        privilege_data
+            .iter()
+            .map(|p| p.user.len())
+            .max()
+            .unwrap_or(example_user.len()),
+        "User".len(),
+    );
 
-    let longest_database_name = privilege_data
-        .iter()
-        .map(|p| p.db.len())
-        .max()
-        .unwrap_or(example_db.len());
+    let longest_database_name = max(
+        privilege_data
+            .iter()
+            .map(|p| p.db.len())
+            .max()
+            .unwrap_or(example_db.len()),
+        "Database".len(),
+    );
 
     let mut header: Vec<_> = DATABASE_PRIVILEGE_FIELDS
         .into_iter()
@@ -578,7 +410,7 @@ pub fn parse_privilege_data_from_editor_content(
 /// instances of privilege sets for a single user on a single database.
 ///
 /// The `User` and `Database` are the same for both instances.
-#[derive(Debug, Clone, PartialEq, Eq, Serialize, PartialOrd, Ord)]
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize, PartialOrd, Ord)]
 pub struct DatabasePrivilegeRowDiff {
     pub db: String,
     pub user: String,
@@ -586,7 +418,7 @@ pub struct DatabasePrivilegeRowDiff {
 }
 
 /// This enum represents a change for a single privilege.
-#[derive(Debug, Clone, PartialEq, Eq, Serialize, PartialOrd, Ord)]
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize, PartialOrd, Ord)]
 pub enum DatabasePrivilegeChange {
     YesToNo(String),
     NoToYes(String),
@@ -603,13 +435,31 @@ impl DatabasePrivilegeChange {
 }
 
 /// This enum encapsulates whether a [`DatabasePrivilegeRow`] was intrduced, modified or deleted.
-#[derive(Debug, Clone, PartialEq, Eq, Serialize, PartialOrd, Ord)]
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize, PartialOrd, Ord)]
 pub enum DatabasePrivilegesDiff {
     New(DatabasePrivilegeRow),
     Modified(DatabasePrivilegeRowDiff),
     Deleted(DatabasePrivilegeRow),
 }
 
+impl DatabasePrivilegesDiff {
+    pub fn get_database_name(&self) -> &str {
+        match self {
+            DatabasePrivilegesDiff::New(p) => &p.db,
+            DatabasePrivilegesDiff::Modified(p) => &p.db,
+            DatabasePrivilegesDiff::Deleted(p) => &p.db,
+        }
+    }
+
+    pub fn get_user_name(&self) -> &str {
+        match self {
+            DatabasePrivilegesDiff::New(p) => &p.user,
+            DatabasePrivilegesDiff::Modified(p) => &p.user,
+            DatabasePrivilegesDiff::Deleted(p) => &p.user,
+        }
+    }
+}
+
 /// This function calculates the differences between two sets of database privileges.
 /// It returns a set of [`DatabasePrivilegesDiff`] that can be used to display or
 /// apply a set of privilege modifications to the database.
@@ -633,7 +483,7 @@ pub fn diff_privileges(
 
     for p in to {
         if let Some(old_p) = from_lookup_table.get(&(p.db.clone(), p.user.clone())) {
-            let diff = old_p.diff(p);
+            let diff = diff(old_p, p);
             if !diff.diff.is_empty() {
                 result.insert(DatabasePrivilegesDiff::Modified(diff));
             }
@@ -651,72 +501,6 @@ pub fn diff_privileges(
     result
 }
 
-/// Uses the result of [`diff_privileges`] to modify privileges in the database.
-pub async fn apply_privilege_diffs(
-    diffs: BTreeSet<DatabasePrivilegesDiff>,
-    connection: &mut MySqlConnection,
-) -> anyhow::Result<()> {
-    for diff in diffs {
-        match diff {
-            DatabasePrivilegesDiff::New(p) => {
-                let tables = DATABASE_PRIVILEGE_FIELDS
-                    .iter()
-                    .map(|field| format!("`{field}`"))
-                    .join(",");
-
-                let question_marks = std::iter::repeat("?")
-                    .take(DATABASE_PRIVILEGE_FIELDS.len())
-                    .join(",");
-
-                sqlx::query(
-                    format!("INSERT INTO `db` ({}) VALUES ({})", tables, question_marks).as_str(),
-                )
-                .bind(p.db)
-                .bind(p.user)
-                .bind(yn(p.select_priv))
-                .bind(yn(p.insert_priv))
-                .bind(yn(p.update_priv))
-                .bind(yn(p.delete_priv))
-                .bind(yn(p.create_priv))
-                .bind(yn(p.drop_priv))
-                .bind(yn(p.alter_priv))
-                .bind(yn(p.index_priv))
-                .bind(yn(p.create_tmp_table_priv))
-                .bind(yn(p.lock_tables_priv))
-                .bind(yn(p.references_priv))
-                .execute(&mut *connection)
-                .await?;
-            }
-            DatabasePrivilegesDiff::Modified(p) => {
-                let tables = p
-                    .diff
-                    .iter()
-                    .map(|diff| match diff {
-                        DatabasePrivilegeChange::YesToNo(name) => format!("`{}` = 'N'", name),
-                        DatabasePrivilegeChange::NoToYes(name) => format!("`{}` = 'Y'", name),
-                    })
-                    .join(",");
-
-                sqlx::query(
-                    format!("UPDATE `db` SET {} WHERE `db` = ? AND `user` = ?", tables).as_str(),
-                )
-                .bind(p.db)
-                .bind(p.user)
-                .execute(&mut *connection)
-                .await?;
-            }
-            DatabasePrivilegesDiff::Deleted(p) => {
-                sqlx::query("DELETE FROM `db` WHERE `db` = ? AND `user` = ?")
-                    .bind(p.db)
-                    .bind(p.user)
-                    .execute(&mut *connection)
-                    .await?;
-            }
-        }
-    }
-    Ok(())
-}
-
 fn display_privilege_cell(diff: &DatabasePrivilegeRowDiff) -> String {
     diff.diff
         .iter()
@@ -731,6 +515,20 @@ fn display_privilege_cell(diff: &DatabasePrivilegeRowDiff) -> String {
         .join("\n")
 }
 
+fn display_new_privileges_list(row: &DatabasePrivilegeRow) -> String {
+    DATABASE_PRIVILEGE_FIELDS
+        .into_iter()
+        .skip(2)
+        .map(|field| {
+            if row.get_privilege_by_name(field) {
+                format!("{}: Y", db_priv_field_human_readable_name(field))
+            } else {
+                format!("{}: N", db_priv_field_human_readable_name(field))
+            }
+        })
+        .join("\n")
+}
+
 /// Displays the difference between two sets of database privileges.
 pub fn display_privilege_diffs(diffs: &BTreeSet<DatabasePrivilegesDiff>) -> String {
     let mut table = Table::new();
@@ -741,24 +539,14 @@ pub fn display_privilege_diffs(diffs: &BTreeSet<DatabasePrivilegesDiff>) -> Stri
                 table.add_row(row![
                     p.db,
                     p.user,
-                    "(New user)\n".to_string()
-                        + &display_privilege_cell(
-                            &DatabasePrivilegeRow::empty(&p.db, &p.user).diff(p)
-                        )
+                    "(New user)\n".to_string() + &display_new_privileges_list(p)
                 ]);
             }
             DatabasePrivilegesDiff::Modified(p) => {
                 table.add_row(row![p.db, p.user, display_privilege_cell(p),]);
             }
             DatabasePrivilegesDiff::Deleted(p) => {
-                table.add_row(row![
-                    p.db,
-                    p.user,
-                    "(All privileges removed)\n".to_string()
-                        + &display_privilege_cell(
-                            &p.diff(&DatabasePrivilegeRow::empty(&p.db, &p.user))
-                        )
-                ]);
+                table.add_row(row![p.db, p.user, "Removed".to_string()]);
             }
         }
     }

src/core/protocol.rs

@@ -0,0 +1,5 @@
+pub mod request_response;
+pub mod server_responses;
+
+pub use request_response::*;
+pub use server_responses::*;

src/core/protocol/request_response.rs

@@ -0,0 +1,79 @@
+use std::collections::BTreeSet;
+
+use serde::{Deserialize, Serialize};
+use tokio::net::UnixStream;
+use tokio_serde::{formats::Bincode, Framed as SerdeFramed};
+use tokio_util::codec::{Framed, LengthDelimitedCodec};
+
+use crate::core::{database_privileges::DatabasePrivilegesDiff, protocol::*};
+
+pub type ServerToClientMessageStream = SerdeFramed<
+    Framed<UnixStream, LengthDelimitedCodec>,
+    Request,
+    Response,
+    Bincode<Request, Response>,
+>;
+
+pub type ClientToServerMessageStream = SerdeFramed<
+    Framed<UnixStream, LengthDelimitedCodec>,
+    Response,
+    Request,
+    Bincode<Response, Request>,
+>;
+
+pub fn create_server_to_client_message_stream(socket: UnixStream) -> ServerToClientMessageStream {
+    let length_delimited = Framed::new(socket, LengthDelimitedCodec::new());
+    tokio_serde::Framed::new(length_delimited, Bincode::default())
+}
+
+pub fn create_client_to_server_message_stream(socket: UnixStream) -> ClientToServerMessageStream {
+    let length_delimited = Framed::new(socket, LengthDelimitedCodec::new());
+    tokio_serde::Framed::new(length_delimited, Bincode::default())
+}
+
+#[non_exhaustive]
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub enum Request {
+    CreateDatabases(Vec<String>),
+    DropDatabases(Vec<String>),
+    ListDatabases,
+    ListPrivileges(Option<Vec<String>>),
+    ModifyPrivileges(BTreeSet<DatabasePrivilegesDiff>),
+
+    CreateUsers(Vec<String>),
+    DropUsers(Vec<String>),
+    PasswdUser(String, String),
+    ListUsers(Option<Vec<String>>),
+    LockUsers(Vec<String>),
+    UnlockUsers(Vec<String>),
+
+    // Commit,
+    Exit,
+}
+
+// TODO: include a generic "message" that will display a message to the user?
+
+#[non_exhaustive]
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub enum Response {
+    // Specific data for specific commands
+    CreateDatabases(CreateDatabasesOutput),
+    DropDatabases(DropDatabasesOutput),
+    ListAllDatabases(ListAllDatabasesOutput),
+    ListPrivileges(GetDatabasesPrivilegeData),
+    ListAllPrivileges(GetAllDatabasesPrivilegeData),
+    ModifyPrivileges(ModifyDatabasePrivilegesOutput),
+
+    CreateUsers(CreateUsersOutput),
+    DropUsers(DropUsersOutput),
+    PasswdUser(SetPasswordOutput),
+    ListUsers(ListUsersOutput),
+    ListAllUsers(ListAllUsersOutput),
+    LockUsers(LockUsersOutput),
+    UnlockUsers(UnlockUsersOutput),
+
+    // Generic responses
+    OperationAborted,
+    Error(String),
+    Exit,
+}

src/core/protocol/server_responses.rs

@@ -0,0 +1,611 @@
+use std::collections::BTreeMap;
+
+use indoc::indoc;
+use itertools::Itertools;
+use serde::{Deserialize, Serialize};
+
+use crate::{
+    core::{common::UnixUser, database_privileges::DatabasePrivilegeRowDiff},
+    server::sql::{
+        database_privilege_operations::DatabasePrivilegeRow, user_operations::DatabaseUser,
+    },
+};
+
+/// This enum is used to differentiate between database and user operations.
+/// Their output are very similar, but there are slight differences in the words used.
+#[derive(Debug, PartialEq, Eq, Clone, Copy)]
+pub enum DbOrUser {
+    Database,
+    User,
+}
+
+impl DbOrUser {
+    pub fn lowercased(&self) -> String {
+        match self {
+            DbOrUser::Database => "database".to_string(),
+            DbOrUser::User => "user".to_string(),
+        }
+    }
+
+    pub fn capitalized(&self) -> String {
+        match self {
+            DbOrUser::Database => "Database".to_string(),
+            DbOrUser::User => "User".to_string(),
+        }
+    }
+}
+
+#[derive(Debug, PartialEq, Eq, Clone, Copy, Serialize, Deserialize)]
+pub enum NameValidationError {
+    EmptyString,
+    InvalidCharacters,
+    TooLong,
+}
+
+impl NameValidationError {
+    pub fn to_error_message(self, name: &str, db_or_user: DbOrUser) -> String {
+        match self {
+            NameValidationError::EmptyString => {
+                format!("{} name cannot be empty.", db_or_user.capitalized()).to_owned()
+            }
+            NameValidationError::TooLong => format!(
+                "{} is too long. Maximum length is 64 characters.",
+                db_or_user.capitalized()
+            )
+            .to_owned(),
+            NameValidationError::InvalidCharacters => format!(
+                indoc! {r#"
+                  Invalid characters in {} name: '{}'
+
+                  Only A-Z, a-z, 0-9, _ (underscore) and - (dash) are permitted.
+                "#},
+                db_or_user.lowercased(),
+                name
+            )
+            .to_owned(),
+        }
+    }
+}
+
+impl OwnerValidationError {
+    pub fn to_error_message(self, name: &str, db_or_user: DbOrUser) -> String {
+        let user = UnixUser::from_enviroment();
+
+        match self {
+            OwnerValidationError::NoMatch => format!(
+                indoc! {r#"
+                  Invalid {} name prefix: '{}' does not match your username or any of your groups.
+                  Are you sure you are allowed to create {} names with this prefix?
+
+                  Allowed prefixes:
+                    - {}
+                  {}
+                "#},
+                db_or_user.lowercased(),
+                name,
+                db_or_user.lowercased(),
+                user.as_ref()
+                    .map(|u| u.username.clone())
+                    .unwrap_or("???".to_string()),
+                user.map(|u| u.groups)
+                    .unwrap_or_default()
+                    .iter()
+                    .map(|g| format!("  - {}", g))
+                    .sorted()
+                    .join("\n"),
+            )
+            .to_owned(),
+
+            _ => format!(
+                "'{}' is not a valid {} name.",
+                name,
+                db_or_user.lowercased()
+            )
+            .to_string(),
+        }
+    }
+}
+
+#[derive(Debug, PartialEq, Eq, Clone, Copy, Serialize, Deserialize)]
+pub enum OwnerValidationError {
+    // The name is valid, but none of the given prefixes matched the name
+    NoMatch,
+
+    // The name is empty, which is invalid
+    StringEmpty,
+
+    // The name is in the format "_<postfix>", which is invalid
+    MissingPrefix,
+
+    // The name is in the format "<prefix>_", which is invalid
+    MissingPostfix,
+}
+
+pub type CreateDatabasesOutput = BTreeMap<String, Result<(), CreateDatabaseError>>;
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub enum CreateDatabaseError {
+    SanitizationError(NameValidationError),
+    OwnershipError(OwnerValidationError),
+    DatabaseAlreadyExists,
+    MySqlError(String),
+}
+
+pub fn print_create_databases_output_status(output: &CreateDatabasesOutput) {
+    for (database_name, result) in output {
+        match result {
+            Ok(()) => {
+                println!("Database '{}' created successfully.", database_name);
+            }
+            Err(err) => {
+                println!("{}", err.to_error_message(database_name));
+                println!("Skipping...");
+            }
+        }
+        println!();
+    }
+}
+
+impl CreateDatabaseError {
+    pub fn to_error_message(&self, database_name: &str) -> String {
+        match self {
+            CreateDatabaseError::SanitizationError(err) => {
+                err.to_error_message(database_name, DbOrUser::Database)
+            }
+            CreateDatabaseError::OwnershipError(err) => {
+                err.to_error_message(database_name, DbOrUser::Database)
+            }
+            CreateDatabaseError::DatabaseAlreadyExists => {
+                format!("Database {} already exists.", database_name)
+            }
+            CreateDatabaseError::MySqlError(err) => {
+                format!("MySQL error: {}", err)
+            }
+        }
+    }
+}
+
+pub type DropDatabasesOutput = BTreeMap<String, Result<(), DropDatabaseError>>;
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub enum DropDatabaseError {
+    SanitizationError(NameValidationError),
+    OwnershipError(OwnerValidationError),
+    DatabaseDoesNotExist,
+    MySqlError(String),
+}
+
+pub fn print_drop_databases_output_status(output: &DropDatabasesOutput) {
+    for (database_name, result) in output {
+        match result {
+            Ok(()) => {
+                println!("Database '{}' dropped successfully.", database_name);
+            }
+            Err(err) => {
+                println!("{}", err.to_error_message(database_name));
+                println!("Skipping...");
+            }
+        }
+        println!();
+    }
+}
+
+impl DropDatabaseError {
+    pub fn to_error_message(&self, database_name: &str) -> String {
+        match self {
+            DropDatabaseError::SanitizationError(err) => {
+                err.to_error_message(database_name, DbOrUser::Database)
+            }
+            DropDatabaseError::OwnershipError(err) => {
+                err.to_error_message(database_name, DbOrUser::Database)
+            }
+            DropDatabaseError::DatabaseDoesNotExist => {
+                format!("Database {} does not exist.", database_name)
+            }
+            DropDatabaseError::MySqlError(err) => {
+                format!("MySQL error: {}", err)
+            }
+        }
+    }
+}
+
+pub type ListAllDatabasesOutput = Result<Vec<String>, ListDatabasesError>;
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub enum ListDatabasesError {
+    MySqlError(String),
+}
+
+impl ListDatabasesError {
+    pub fn to_error_message(&self) -> String {
+        match self {
+            ListDatabasesError::MySqlError(err) => format!("MySQL error: {}", err),
+        }
+    }
+}
+
+// TODO: merge all rows into a single collection.
+//       they already contain which database they belong to.
+//       no need to index by database name.
+
+pub type GetDatabasesPrivilegeData =
+    BTreeMap<String, Result<Vec<DatabasePrivilegeRow>, GetDatabasesPrivilegeDataError>>;
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub enum GetDatabasesPrivilegeDataError {
+    SanitizationError(NameValidationError),
+    OwnershipError(OwnerValidationError),
+    DatabaseDoesNotExist,
+    MySqlError(String),
+}
+
+impl GetDatabasesPrivilegeDataError {
+    pub fn to_error_message(&self, database_name: &str) -> String {
+        match self {
+            GetDatabasesPrivilegeDataError::SanitizationError(err) => {
+                err.to_error_message(database_name, DbOrUser::Database)
+            }
+            GetDatabasesPrivilegeDataError::OwnershipError(err) => {
+                err.to_error_message(database_name, DbOrUser::Database)
+            }
+            GetDatabasesPrivilegeDataError::DatabaseDoesNotExist => {
+                format!("Database '{}' does not exist.", database_name)
+            }
+            GetDatabasesPrivilegeDataError::MySqlError(err) => {
+                format!("MySQL error: {}", err)
+            }
+        }
+    }
+}
+
+pub type GetAllDatabasesPrivilegeData =
+    Result<Vec<DatabasePrivilegeRow>, GetAllDatabasesPrivilegeDataError>;
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub enum GetAllDatabasesPrivilegeDataError {
+    MySqlError(String),
+}
+
+impl GetAllDatabasesPrivilegeDataError {
+    pub fn to_error_message(&self) -> String {
+        match self {
+            GetAllDatabasesPrivilegeDataError::MySqlError(err) => format!("MySQL error: {}", err),
+        }
+    }
+}
+
+pub type ModifyDatabasePrivilegesOutput =
+    BTreeMap<(String, String), Result<(), ModifyDatabasePrivilegesError>>;
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub enum ModifyDatabasePrivilegesError {
+    DatabaseSanitizationError(NameValidationError),
+    DatabaseOwnershipError(OwnerValidationError),
+    UserSanitizationError(NameValidationError),
+    UserOwnershipError(OwnerValidationError),
+    DatabaseDoesNotExist,
+    DiffDoesNotApply(DiffDoesNotApplyError),
+    MySqlError(String),
+}
+
+#[allow(clippy::enum_variant_names)]
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub enum DiffDoesNotApplyError {
+    RowAlreadyExists(String, String),
+    RowDoesNotExist(String, String),
+    RowPrivilegeChangeDoesNotApply(DatabasePrivilegeRowDiff, DatabasePrivilegeRow),
+}
+
+pub fn print_modify_database_privileges_output_status(output: &ModifyDatabasePrivilegesOutput) {
+    for ((database_name, username), result) in output {
+        match result {
+            Ok(()) => {
+                println!(
+                    "Privileges for user '{}' on database '{}' modified successfully.",
+                    username, database_name
+                );
+            }
+            Err(err) => {
+                println!("{}", err.to_error_message(database_name, username));
+                println!("Skipping...");
+            }
+        }
+        println!();
+    }
+}
+
+impl ModifyDatabasePrivilegesError {
+    pub fn to_error_message(&self, database_name: &str, username: &str) -> String {
+        match self {
+            ModifyDatabasePrivilegesError::DatabaseSanitizationError(err) => {
+                err.to_error_message(database_name, DbOrUser::Database)
+            }
+            ModifyDatabasePrivilegesError::DatabaseOwnershipError(err) => {
+                err.to_error_message(database_name, DbOrUser::Database)
+            }
+            ModifyDatabasePrivilegesError::UserSanitizationError(err) => {
+                err.to_error_message(username, DbOrUser::User)
+            }
+            ModifyDatabasePrivilegesError::UserOwnershipError(err) => {
+                err.to_error_message(username, DbOrUser::User)
+            }
+            ModifyDatabasePrivilegesError::DatabaseDoesNotExist => {
+                format!("Database '{}' does not exist.", database_name)
+            }
+            ModifyDatabasePrivilegesError::DiffDoesNotApply(diff) => {
+                format!(
+                    "Could not apply privilege change:\n{}",
+                    diff.to_error_message()
+                )
+            }
+            ModifyDatabasePrivilegesError::MySqlError(err) => {
+                format!("MySQL error: {}", err)
+            }
+        }
+    }
+}
+
+impl DiffDoesNotApplyError {
+    pub fn to_error_message(&self) -> String {
+        match self {
+            DiffDoesNotApplyError::RowAlreadyExists(database_name, username) => {
+                format!(
+                    "Privileges for user '{}' on database '{}' already exist.",
+                    username, database_name
+                )
+            }
+            DiffDoesNotApplyError::RowDoesNotExist(database_name, username) => {
+                format!(
+                    "Privileges for user '{}' on database '{}' do not exist.",
+                    username, database_name
+                )
+            }
+            DiffDoesNotApplyError::RowPrivilegeChangeDoesNotApply(diff, row) => {
+                format!(
+                    "Could not apply privilege change {:?} to row {:?}",
+                    diff, row
+                )
+            }
+        }
+    }
+}
+
+pub type CreateUsersOutput = BTreeMap<String, Result<(), CreateUserError>>;
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub enum CreateUserError {
+    SanitizationError(NameValidationError),
+    OwnershipError(OwnerValidationError),
+    UserAlreadyExists,
+    MySqlError(String),
+}
+
+pub fn print_create_users_output_status(output: &CreateUsersOutput) {
+    for (username, result) in output {
+        match result {
+            Ok(()) => {
+                println!("User '{}' created successfully.", username);
+            }
+            Err(err) => {
+                println!("{}", err.to_error_message(username));
+                println!("Skipping...");
+            }
+        }
+        println!();
+    }
+}
+
+impl CreateUserError {
+    pub fn to_error_message(&self, username: &str) -> String {
+        match self {
+            CreateUserError::SanitizationError(err) => {
+                err.to_error_message(username, DbOrUser::User)
+            }
+            CreateUserError::OwnershipError(err) => err.to_error_message(username, DbOrUser::User),
+            CreateUserError::UserAlreadyExists => {
+                format!("User '{}' already exists.", username)
+            }
+            CreateUserError::MySqlError(err) => {
+                format!("MySQL error: {}", err)
+            }
+        }
+    }
+}
+
+pub type DropUsersOutput = BTreeMap<String, Result<(), DropUserError>>;
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub enum DropUserError {
+    SanitizationError(NameValidationError),
+    OwnershipError(OwnerValidationError),
+    UserDoesNotExist,
+    MySqlError(String),
+}
+
+pub fn print_drop_users_output_status(output: &DropUsersOutput) {
+    for (username, result) in output {
+        match result {
+            Ok(()) => {
+                println!("User '{}' dropped successfully.", username);
+            }
+            Err(err) => {
+                println!("{}", err.to_error_message(username));
+                println!("Skipping...");
+            }
+        }
+        println!();
+    }
+}
+
+impl DropUserError {
+    pub fn to_error_message(&self, username: &str) -> String {
+        match self {
+            DropUserError::SanitizationError(err) => err.to_error_message(username, DbOrUser::User),
+            DropUserError::OwnershipError(err) => err.to_error_message(username, DbOrUser::User),
+            DropUserError::UserDoesNotExist => {
+                format!("User '{}' does not exist.", username)
+            }
+            DropUserError::MySqlError(err) => {
+                format!("MySQL error: {}", err)
+            }
+        }
+    }
+}
+
+pub type SetPasswordOutput = Result<(), SetPasswordError>;
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub enum SetPasswordError {
+    SanitizationError(NameValidationError),
+    OwnershipError(OwnerValidationError),
+    UserDoesNotExist,
+    MySqlError(String),
+}
+
+pub fn print_set_password_output_status(output: &SetPasswordOutput, username: &str) {
+    match output {
+        Ok(()) => {
+            println!("Password for user '{}' set successfully.", username);
+        }
+        Err(err) => {
+            println!("{}", err.to_error_message(username));
+            println!("Skipping...");
+        }
+    }
+}
+
+impl SetPasswordError {
+    pub fn to_error_message(&self, username: &str) -> String {
+        match self {
+            SetPasswordError::SanitizationError(err) => {
+                err.to_error_message(username, DbOrUser::User)
+            }
+            SetPasswordError::OwnershipError(err) => err.to_error_message(username, DbOrUser::User),
+            SetPasswordError::UserDoesNotExist => {
+                format!("User '{}' does not exist.", username)
+            }
+            SetPasswordError::MySqlError(err) => {
+                format!("MySQL error: {}", err)
+            }
+        }
+    }
+}
+
+pub type LockUsersOutput = BTreeMap<String, Result<(), LockUserError>>;
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub enum LockUserError {
+    SanitizationError(NameValidationError),
+    OwnershipError(OwnerValidationError),
+    UserDoesNotExist,
+    UserIsAlreadyLocked,
+    MySqlError(String),
+}
+
+pub fn print_lock_users_output_status(output: &LockUsersOutput) {
+    for (username, result) in output {
+        match result {
+            Ok(()) => {
+                println!("User '{}' locked successfully.", username);
+            }
+            Err(err) => {
+                println!("{}", err.to_error_message(username));
+                println!("Skipping...");
+            }
+        }
+        println!();
+    }
+}
+
+impl LockUserError {
+    pub fn to_error_message(&self, username: &str) -> String {
+        match self {
+            LockUserError::SanitizationError(err) => err.to_error_message(username, DbOrUser::User),
+            LockUserError::OwnershipError(err) => err.to_error_message(username, DbOrUser::User),
+            LockUserError::UserDoesNotExist => {
+                format!("User '{}' does not exist.", username)
+            }
+            LockUserError::UserIsAlreadyLocked => {
+                format!("User '{}' is already locked.", username)
+            }
+            LockUserError::MySqlError(err) => {
+                format!("MySQL error: {}", err)
+            }
+        }
+    }
+}
+
+pub type UnlockUsersOutput = BTreeMap<String, Result<(), UnlockUserError>>;
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub enum UnlockUserError {
+    SanitizationError(NameValidationError),
+    OwnershipError(OwnerValidationError),
+    UserDoesNotExist,
+    UserIsAlreadyUnlocked,
+    MySqlError(String),
+}
+
+pub fn print_unlock_users_output_status(output: &UnlockUsersOutput) {
+    for (username, result) in output {
+        match result {
+            Ok(()) => {
+                println!("User '{}' unlocked successfully.", username);
+            }
+            Err(err) => {
+                println!("{}", err.to_error_message(username));
+                println!("Skipping...");
+            }
+        }
+        println!();
+    }
+}
+
+impl UnlockUserError {
+    pub fn to_error_message(&self, username: &str) -> String {
+        match self {
+            UnlockUserError::SanitizationError(err) => {
+                err.to_error_message(username, DbOrUser::User)
+            }
+            UnlockUserError::OwnershipError(err) => err.to_error_message(username, DbOrUser::User),
+            UnlockUserError::UserDoesNotExist => {
+                format!("User '{}' does not exist.", username)
+            }
+            UnlockUserError::UserIsAlreadyUnlocked => {
+                format!("User '{}' is already unlocked.", username)
+            }
+            UnlockUserError::MySqlError(err) => {
+                format!("MySQL error: {}", err)
+            }
+        }
+    }
+}
+
+pub type ListUsersOutput = BTreeMap<String, Result<DatabaseUser, ListUsersError>>;
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub enum ListUsersError {
+    SanitizationError(NameValidationError),
+    OwnershipError(OwnerValidationError),
+    UserDoesNotExist,
+    MySqlError(String),
+}
+
+impl ListUsersError {
+    pub fn to_error_message(&self, username: &str) -> String {
+        match self {
+            ListUsersError::SanitizationError(err) => {
+                err.to_error_message(username, DbOrUser::User)
+            }
+            ListUsersError::OwnershipError(err) => err.to_error_message(username, DbOrUser::User),
+            ListUsersError::UserDoesNotExist => {
+                format!("User '{}' does not exist.", username)
+            }
+            ListUsersError::MySqlError(err) => {
+                format!("MySQL error: {}", err)
+            }
+        }
+    }
+}
+
+pub type ListAllUsersOutput = Result<Vec<DatabaseUser>, ListAllUsersError>;
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
+pub enum ListAllUsersError {
+    MySqlError(String),
+}
+
+impl ListAllUsersError {
+    pub fn to_error_message(&self) -> String {
+        match self {
+            ListAllUsersError::MySqlError(err) => format!("MySQL error: {}", err),
+        }
+    }
+}

src/core/user_operations.rs

@@ -1,249 +0,0 @@
-use anyhow::Context;
-use nix::unistd::User;
-use serde::{Deserialize, Serialize};
-use sqlx::{prelude::*, MySqlConnection};
-
-use crate::core::common::{
-    create_user_group_matching_regex, get_current_unix_user, quote_literal, validate_name_or_error,
-    validate_ownership_or_error, DbOrUser,
-};
-
-pub async fn user_exists(db_user: &str, connection: &mut MySqlConnection) -> anyhow::Result<bool> {
-    let unix_user = get_current_unix_user()?;
-
-    validate_user_name(db_user, &unix_user)?;
-
-    let user_exists = sqlx::query(
-        r#"
-          SELECT EXISTS(
-            SELECT 1
-            FROM `mysql`.`user`
-            WHERE `User` = ?
-          )
-        "#,
-    )
-    .bind(db_user)
-    .fetch_one(connection)
-    .await?
-    .get::<bool, _>(0);
-
-    Ok(user_exists)
-}
-
-pub async fn create_database_user(
-    db_user: &str,
-    connection: &mut MySqlConnection,
-) -> anyhow::Result<()> {
-    let unix_user = get_current_unix_user()?;
-
-    validate_user_name(db_user, &unix_user)?;
-
-    if user_exists(db_user, connection).await? {
-        anyhow::bail!("User '{}' already exists", db_user);
-    }
-
-    // NOTE: see the note about SQL injections in `validate_ownership_of_user_name`
-    sqlx::query(format!("CREATE USER {}@'%'", quote_literal(db_user),).as_str())
-        .execute(connection)
-        .await?;
-
-    Ok(())
-}
-
-pub async fn delete_database_user(
-    db_user: &str,
-    connection: &mut MySqlConnection,
-) -> anyhow::Result<()> {
-    let unix_user = get_current_unix_user()?;
-
-    validate_user_name(db_user, &unix_user)?;
-
-    if !user_exists(db_user, connection).await? {
-        anyhow::bail!("User '{}' does not exist", db_user);
-    }
-
-    // NOTE: see the note about SQL injections in `validate_ownership_of_user_name`
-    sqlx::query(format!("DROP USER {}@'%'", quote_literal(db_user),).as_str())
-        .execute(connection)
-        .await?;
-
-    Ok(())
-}
-
-pub async fn set_password_for_database_user(
-    db_user: &str,
-    password: &str,
-    connection: &mut MySqlConnection,
-) -> anyhow::Result<()> {
-    let unix_user = crate::core::common::get_current_unix_user()?;
-    validate_user_name(db_user, &unix_user)?;
-
-    if !user_exists(db_user, connection).await? {
-        anyhow::bail!("User '{}' does not exist", db_user);
-    }
-
-    // NOTE: see the note about SQL injections in `validate_ownership_of_user_name`
-    sqlx::query(
-        format!(
-            "ALTER USER {}@'%' IDENTIFIED BY {}",
-            quote_literal(db_user),
-            quote_literal(password).as_str()
-        )
-        .as_str(),
-    )
-    .execute(connection)
-    .await?;
-
-    Ok(())
-}
-
-async fn user_is_locked(db_user: &str, connection: &mut MySqlConnection) -> anyhow::Result<bool> {
-    let unix_user = get_current_unix_user()?;
-
-    validate_user_name(db_user, &unix_user)?;
-
-    if !user_exists(db_user, connection).await? {
-        anyhow::bail!("User '{}' does not exist", db_user);
-    }
-
-    let is_locked = sqlx::query(
-        r#"
-          SELECT JSON_EXTRACT(`mysql`.`global_priv`.`priv`, "$.account_locked") = 'true'
-          FROM `mysql`.`global_priv`
-          WHERE `User` = ?
-          AND `Host` = '%'
-        "#,
-    )
-    .bind(db_user)
-    .fetch_one(connection)
-    .await?
-    .get::<bool, _>(0);
-
-    Ok(is_locked)
-}
-
-pub async fn lock_database_user(
-    db_user: &str,
-    connection: &mut MySqlConnection,
-) -> anyhow::Result<()> {
-    let unix_user = get_current_unix_user()?;
-
-    validate_user_name(db_user, &unix_user)?;
-
-    if !user_exists(db_user, connection).await? {
-        anyhow::bail!("User '{}' does not exist", db_user);
-    }
-
-    if user_is_locked(db_user, connection).await? {
-        anyhow::bail!("User '{}' is already locked", db_user);
-    }
-
-    // NOTE: see the note about SQL injections in `validate_ownership_of_user_name`
-    sqlx::query(format!("ALTER USER {}@'%' ACCOUNT LOCK", quote_literal(db_user),).as_str())
-        .execute(connection)
-        .await?;
-
-    Ok(())
-}
-
-pub async fn unlock_database_user(
-    db_user: &str,
-    connection: &mut MySqlConnection,
-) -> anyhow::Result<()> {
-    let unix_user = get_current_unix_user()?;
-
-    validate_user_name(db_user, &unix_user)?;
-
-    if !user_exists(db_user, connection).await? {
-        anyhow::bail!("User '{}' does not exist", db_user);
-    }
-
-    if !user_is_locked(db_user, connection).await? {
-        anyhow::bail!("User '{}' is already unlocked", db_user);
-    }
-
-    // NOTE: see the note about SQL injections in `validate_ownership_of_user_name`
-    sqlx::query(format!("ALTER USER {}@'%' ACCOUNT UNLOCK", quote_literal(db_user),).as_str())
-        .execute(connection)
-        .await?;
-
-    Ok(())
-}
-
-/// This struct contains information about a database user.
-/// This can be extended if we need more information in the future.
-#[derive(Debug, Clone, FromRow, Serialize, Deserialize)]
-pub struct DatabaseUser {
-    #[sqlx(rename = "User")]
-    pub user: String,
-
-    #[allow(dead_code)]
-    #[serde(skip)]
-    #[sqlx(rename = "Host")]
-    pub host: String,
-
-    #[sqlx(rename = "has_password")]
-    pub has_password: bool,
-
-    #[sqlx(rename = "is_locked")]
-    pub is_locked: bool,
-}
-
-const DB_USER_SELECT_STATEMENT: &str = r#"
-SELECT
-  `mysql`.`user`.`User`,
-  `mysql`.`user`.`Host`,
-  `mysql`.`user`.`Password` != '' OR `mysql`.`user`.`authentication_string` != '' AS `has_password`,
-  COALESCE(
-    JSON_EXTRACT(`mysql`.`global_priv`.`priv`, "$.account_locked"),
-    'false'
-  ) != 'false' AS `is_locked`
-FROM `mysql`.`user`
-JOIN `mysql`.`global_priv` ON
-  `mysql`.`user`.`User` = `mysql`.`global_priv`.`User`
-  AND `mysql`.`user`.`Host` = `mysql`.`global_priv`.`Host`
-"#;
-
-/// This function fetches all database users that have a prefix matching the
-/// unix username and group names of the given unix user.
-pub async fn get_all_database_users_for_unix_user(
-    unix_user: &User,
-    connection: &mut MySqlConnection,
-) -> anyhow::Result<Vec<DatabaseUser>> {
-    let users = sqlx::query_as::<_, DatabaseUser>(
-        &(DB_USER_SELECT_STATEMENT.to_string() + "WHERE `mysql`.`user`.`User` REGEXP ?"),
-    )
-    .bind(create_user_group_matching_regex(unix_user))
-    .fetch_all(connection)
-    .await?;
-
-    Ok(users)
-}
-
-/// This function fetches a database user if it exists.
-pub async fn get_database_user_for_user(
-    username: &str,
-    connection: &mut MySqlConnection,
-) -> anyhow::Result<Option<DatabaseUser>> {
-    let user = sqlx::query_as::<_, DatabaseUser>(
-        &(DB_USER_SELECT_STATEMENT.to_string() + "WHERE `mysql`.`user`.`User` = ?"),
-    )
-    .bind(username)
-    .fetch_optional(connection)
-    .await?;
-
-    Ok(user)
-}
-
-/// NOTE: It is very critical that this function validates the database name
-///       properly. MySQL does not seem to allow for prepared statements, binding
-///       the database name as a parameter to the query. This means that we have
-///       to validate the database name ourselves to prevent SQL injection.
-pub fn validate_user_name(name: &str, user: &User) -> anyhow::Result<()> {
-    validate_name_or_error(name, DbOrUser::User)
-        .context(format!("Invalid username: '{}'", name))?;
-    validate_ownership_or_error(name, user, DbOrUser::User)
-        .context(format!("Invalid username: '{}'", name))?;
-
-    Ok(())
-}