max / makenotwork

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1	//! Crate error type.
2	//!
3	//! [`ChatError::Host`] is the seam for the host app: a trait impl that fails in
4	//! the database or in its own authz layer boxes that error rather than the crate
5	//! trying to name every failure either consumer might have.
6
7	use std::time::Duration;
8
9	/// Which budget a connection ran out of.
10	///
11	/// Worth distinguishing: [`LimitScope::User`] means this client should close a
12	/// tab, while [`LimitScope::Global`] means the process is saturated and is a
13	/// signal an operator needs, not an end user.
14	#[derive(Debug, Clone, Copy, PartialEq, Eq)]
15	pub enum LimitScope {
16	/// This user holds too many concurrent connections.
17	User,
18	/// The process is at its total connection budget.
19	Global,
20	}
21
22	impl std::fmt::Display for LimitScope {
23	fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
24	match self {
25	Self::User => f.write_str("per-user"),
26	Self::Global => f.write_str("global"),
27	}
28	}
29	}
30
31	/// Anything that can go wrong in the crate or in a host's trait impl.
32	#[derive(Debug, thiserror::Error)]
33	pub enum ChatError {
34	#[error(
35	"retention exceeds the crate ceiling (asked for {max_age:?} / {max_messages} messages)"
36	)]
37	RetentionTooLong {
38	max_age: Duration,
39	max_messages: usize,
40	},
41
42	#[error("retention must be non-zero in both bounds")]
43	RetentionTooShort,
44
45	#[error("message is {len} characters, over the {max} character limit")]
46	MessageTooLong { len: usize, max: usize },
47
48	#[error("message is empty")]
49	MessageEmpty,
50
51	#[error("invalid send nonce")]
52	InvalidNonce,
53
54	#[error("room is closed")]
55	RoomClosed,
56
57	#[error("room is read-only")]
58	RoomReadOnly,
59
60	/// At capacity. The caller has already passed authz by this point, so this is
61	/// a resource refusal and belongs in the 503 family, not the 403 one.
62	#[error("connection limit reached ({0})")]
63	ConnectionLimit(LimitScope),
64
65	/// The sender did something the room refused. Distinct from a host error:
66	/// this is expected traffic, not a fault, and should not be logged as one.
67	#[error("send rejected: {0:?}")]
68	Rejected(crate::send::SendRejection),
69
70	/// An error from the host app's trait impl: a query failure, a session
71	/// lookup, anything the crate has no vocabulary for.
72	#[error("host error: {0}")]
73	Host(#[source] Box<dyn std::error::Error + Send + Sync>),
74	}
75
76	impl ChatError {
77	/// Wrap a host-side error.
78	pub fn host<E: std::error::Error + Send + Sync + 'static>(err: E) -> Self {
79	Self::Host(Box::new(err))
80	}
81	}
82