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roowho2/src/server/varlink_api/walld.rs
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server/walld: init
2026-07-28 20:29:46 +09:00

277 lines
8.9 KiB
Rust

use std::time::Duration;
use nix::unistd::gethostname;
use serde::{Deserialize, Serialize};
use zlink::ReplyError;
use crate::server::walld::tty_utils::{self, TtyError};
#[zlink::proxy("no.ntnu.pvv.roowho2.walld")]
pub trait VarlinkWalldClientProxy {
/// Broadcast `message` to the tty of every logged in user, optionally restricted to `group`.
async fn wall(
&mut self,
source_tty: Option<String>,
message: String,
group: Option<String>,
nobanner: bool,
timeout_secs: u32,
) -> zlink::Result<Result<VarlinkWalldClientResponse, VarlinkWalldClientError>>;
/// Send `message` to a the tty of a single user, optionally targeting a specific tty.
async fn write(
&mut self,
source_tty: Option<String>,
target_user: String,
target_tty: Option<String>,
message: String,
) -> zlink::Result<Result<VarlinkWalldClientResponse, VarlinkWalldClientError>>;
}
#[derive(Debug, Deserialize)]
#[serde(tag = "method", content = "parameters")]
pub enum VarlinkWalldClientRequest {
#[serde(rename = "no.ntnu.pvv.roowho2.walld.Wall")]
Wall {
source_tty: Option<String>,
message: String,
group: Option<String>,
nobanner: bool,
timeout_secs: u32,
},
#[serde(rename = "no.ntnu.pvv.roowho2.walld.Write")]
Write {
source_tty: Option<String>,
target_user: String,
target_tty: Option<String>,
message: String,
},
}
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
#[serde(untagged)]
pub enum VarlinkWalldClientResponse {
Wall(VarlinkWallResponse),
Write(VarlinkWriteResponse),
}
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize, Default)]
pub struct VarlinkWallResponse {
pub delivered: Vec<VarlinkWallDelivery>,
pub failures: Vec<VarlinkWallDeliveryFailure>,
}
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
pub struct VarlinkWallDelivery {
pub user: String,
pub tty: String,
}
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
pub struct VarlinkWallDeliveryFailure {
pub user: String,
pub tty: String,
pub reason: String,
}
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize, Default)]
pub struct VarlinkWriteResponse {
/// The tty the message was actually delivered to.
/// This is relevant when the caller didn't specify one, and it was picked automatically.
pub tty: String,
}
#[derive(Debug, Clone, PartialEq, ReplyError)]
#[zlink(interface = "no.ntnu.pvv.roowho2.walld")]
pub enum VarlinkWalldClientError {
/// The walld service is not enabled on the server.
Disabled,
/// Caller was not authorized by polkit to perform the request.
NotAuthorized,
/// The target user is not logged in anywhere.
UserNotLoggedIn { user: String },
/// The target user has disabled incoming messages on the relevant tty/ttys.
MessagesDisabled { user: String },
/// The requested tty does not belong to the target user, or does not exist.
TtyNotFound { user: String, tty: String },
/// The request parameters were invalid (e.g. unknown group).
InvalidRequest { message: String },
/// The request timed out.
TimedOut,
/// Something went wrong while talking to the tty (open/write failure).
Io { message: String },
}
// TODO: use `thiserror` to derive `Display` the impl instead.
impl std::fmt::Display for VarlinkWalldClientError {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
match self {
VarlinkWalldClientError::Disabled => {
write!(f, "The walld service is disabled on the server")
}
VarlinkWalldClientError::NotAuthorized => write!(f, "Caller is not authorized"),
VarlinkWalldClientError::UserNotLoggedIn { user } => {
write!(f, "User '{}' is not logged in", user)
}
VarlinkWalldClientError::MessagesDisabled { user } => {
write!(f, "User '{}' has disabled incoming messages", user)
}
VarlinkWalldClientError::TtyNotFound { user, tty } => {
write!(f, "Tty '{}' not found for user '{}'", tty, user)
}
VarlinkWalldClientError::InvalidRequest { message } => {
write!(f, "Invalid request: {}", message)
}
VarlinkWalldClientError::TimedOut => write!(f, "Request timed out"),
VarlinkWalldClientError::Io { message } => {
write!(f, "I/O error while sending message: {}", message)
}
}
}
}
fn username_for_uid(uid: u32) -> String {
users::get_user_by_uid(uid)
.map(|u| u.name().to_string_lossy().into_owned())
.unwrap_or_else(|| uid.to_string())
}
fn hostname() -> String {
gethostname()
.ok()
.and_then(|h| h.into_string().ok())
.unwrap_or_else(|| "unknown".to_string())
}
fn tty_error_to_walld_error(user: &str, tty: &str, err: TtyError) -> VarlinkWalldClientError {
match err {
TtyError::NotFound(_) | TtyError::InvalidName(_) | TtyError::NotCharacterDevice(_) => {
VarlinkWalldClientError::TtyNotFound {
user: user.to_string(),
tty: tty.to_string(),
}
}
TtyError::Unavailable(_) => VarlinkWalldClientError::MessagesDisabled {
user: user.to_string(),
},
other => VarlinkWalldClientError::Io {
message: other.to_string(),
},
}
}
// TODO: have the client send the name of the TTY
// verify that the TTY is owned by the user from peercred.
pub async fn handle_wall_request(
_source_pid: u32,
source_uid: u32,
source_tty: Option<String>,
message: String,
group: Option<String>,
nobanner: bool,
timeout_secs: u32,
) -> Result<VarlinkWallResponse, VarlinkWalldClientError> {
if let Some(group) = &group
&& users::get_group_by_name(group).is_none()
{
return Err(VarlinkWalldClientError::InvalidRequest {
message: format!("unknown group {group:?}"),
});
}
// TODO: authorize against polkit
let body = tty_utils::format_wall_message(
&username_for_uid(source_uid),
&hostname(),
source_tty.as_deref(),
&message,
nobanner,
);
let timeout = Duration::from_secs(timeout_secs.max(1) as u64);
let sessions = tty_utils::all_sessions(group.as_deref());
let mut response = VarlinkWallResponse::default();
for session in sessions {
match tty_utils::deliver_message(&session.tty, &body, timeout).await {
Ok(()) => response.delivered.push(VarlinkWallDelivery {
user: session.user,
tty: session.tty,
}),
Err(err) => response.failures.push(VarlinkWallDeliveryFailure {
user: session.user,
tty: session.tty,
reason: err.to_string(),
}),
}
}
Ok(response)
}
const DEFAULT_WRITE_TIMEOUT: Duration = Duration::from_secs(30);
pub async fn handle_write_request(
_source_pid: u32,
source_uid: u32,
source_tty: Option<String>,
user: String,
tty: Option<String>,
message: String,
) -> Result<VarlinkWriteResponse, VarlinkWalldClientError> {
// TODO: authorize against polkit
let sessions = tty_utils::sessions_for_user(&user);
if sessions.is_empty() {
return Err(VarlinkWalldClientError::UserNotLoggedIn { user });
}
let target_tty = match &tty {
Some(tty) => {
if !sessions.iter().any(|s| &s.tty == tty) {
return Err(VarlinkWalldClientError::TtyNotFound {
user,
tty: tty.clone(),
});
}
tty.clone()
}
// No tty requested, pick the one the user touched most recently
None => sessions
.iter()
.filter_map(|s| {
tty_utils::stat_tty(&s.tty)
.ok()
.map(|info| (s.tty.clone(), info))
})
.max_by_key(|(_, info)| info.atime)
.map(|(tty, _)| tty)
.ok_or_else(|| VarlinkWalldClientError::MessagesDisabled { user: user.clone() })?,
};
match tty_utils::stat_tty(&target_tty) {
Ok(info) if info.writable => {}
Ok(_) => return Err(VarlinkWalldClientError::MessagesDisabled { user }),
Err(_) => {
return Err(VarlinkWalldClientError::TtyNotFound {
user,
tty: target_tty,
});
}
}
let source_user = username_for_uid(source_uid);
let body =
tty_utils::format_write_message(&source_user, &hostname(), source_tty.as_deref(), &message);
tty_utils::deliver_message(&target_tty, &body, DEFAULT_WRITE_TIMEOUT)
.await
.map_err(|err| tty_error_to_walld_error(&user, &target_tty, err))?;
Ok(VarlinkWriteResponse { tty: target_tty })
}