Struct ClientConfig 

#[non_exhaustive]
pub struct ClientConfig {
    pub request_timeout: Duration,
    pub max_session_body: u64,
    pub max_call_body: u64,
    pub max_download_body: u64,
    pub max_upload_response_body: u64,
    pub max_sse_frame: usize,
    pub max_ws_message: usize,
}

Per-client configuration for timeouts and body size limits.

Use ClientConfig::default() for production defaults (30s timeout, RFC-safe caps).

This type is #[non_exhaustive]: callers outside this crate must use ..ClientConfig::default() when constructing it, allowing new fields to be added in minor versions without breaking callers.

Field-type rationale (bd:JMAP-6r7c.21)

The fields mix u64 and usize integer types. The split is deliberate and tracks the underlying transport’s expectations:

• HTTP body caps are u64 (max_session_body, max_call_body, max_download_body, max_upload_response_body). reqwest reports Content-Length as u64, and an HTTP body can in principle exceed usize::MAX on a 32-bit target (4 GiB) without exceeding 64-bit limits; the cap comparison happens before accumulation.
• In-memory frame/message caps are usize (max_sse_frame, max_ws_message). These bound a Vec<u8> or String that must fit in process memory; usize is the address-space-native type and matches what tokio_tungstenite::tungstenite::protocol::WebSocketConfig expects.

A future minor release MAY consolidate on u64 with internal usize::try_from casts at the call sites that need it. The mixed-int API is a small ergonomic cost (callers cannot pass the same untyped integer literal to both kinds of field without a _u64 or _usize suffix or as usize cast) traded for transparency to the underlying transport’s contract.

No cross-field invariants are enforced

validate() checks each field independently. There is intentionally no constraint that max_sse_frame <= max_call_body or similar — they govern different threats (per-frame buffer cap vs whole-body cap) and a deployment may rationally configure them in either order. Document the chosen values in your own deployment notes.

Fields (Non-exhaustive)

Non-exhaustive structs could have additional fields added in future. Therefore, non-exhaustive structs cannot be constructed in external crates using the traditional Struct { .. } syntax; cannot be matched against without a wildcard ..; and struct update syntax will not work.

request_timeout: Duration

Timeout for HTTP request/response cycles (fetch_session, call, upload_blob, download_blob). Does NOT apply to SSE or WebSocket streams (which are indefinite by nature). Must be > 0. Use Duration::from_secs(30) for a 30-second timeout. Default: 30 seconds.

Duration::ZERO is forbidden because reqwest::RequestBuilder::timeout treats Duration::ZERO as “no per-request timeout” (only the client-level connect_timeout applies), not “instant fail”. A future maintainer who thinks “zero means disable timeout, why not allow it?” is reading reqwest’s semantics correctly but missing that this crate intentionally forbids the no-timeout configuration: a caller-visible 30-second-by-default timeout protects against indefinite hangs on stalled servers and against a slowloris-style resource leak in JMAP clients that hold one outstanding request per account. validate() enforces the positive-timeout invariant (bd:JMAP-6r7c.29). Do not relax this without re-deriving the no-timeout DoS argument.

max_session_body: u64

Maximum response body for fetch_session. Default: 1 MiB.

max_call_body: u64

Maximum response body for call(). Default: 8 MiB.

max_download_body: u64

Maximum response body for download_blob(). Default: 64 MiB.

max_upload_response_body: u64

Maximum size in bytes of the JSON response body returned by the server in reply to upload_blob(). Does NOT cap the size of the blob being uploaded — the JMAP server enforces that via its maxSizeUpload capability. This field caps only the small JSON envelope the server returns describing the stored blob. Default: 1 MiB.

max_sse_frame: usize

Maximum byte length of a single SSE frame; applied independently to the raw incoming bytes (pre-UTF-8 decode) and the decoded text. Protects against memory exhaustion from a hostile or misbehaving server that sends a single very large frame. Must be > 0. Default: 1 MiB.

Memory residency note (bd:JMAP-6lsm.7): because the raw byte buffer and the decoded text buffer are tracked separately, the in-flight footprint while parsing a single frame can momentarily reach ~2 × max_sse_frame (raw bytes accumulated up to the limit, plus decoded text not yet drained). If you tune this value for a tight memory budget, plan for that 2× peak. The independent tracking is correct for the streaming UTF-8 decoder (which needs the raw buffer to be at least one full frame to handle split multi-byte sequences across HTTP chunks); see decode_utf8_chunk for the rationale.

max_ws_message: usize

Maximum byte length of a single WebSocket message (and frame). Mirrors max_sse_frame for the WebSocket transport. Used by JmapClient::connect_ws_session and threaded through to tokio_tungstenite::tungstenite::protocol::WebSocketConfig’s max_message_size and max_frame_size. Must be > 0. Default: 1 MiB. (bd:JMAP-6lsm.5)

Implementations

impl ClientConfig

pub fn validate(&self) -> Result<(), ClientError>

Validate that all config fields satisfy their constraints.

Called automatically by JmapClient::new. Callers may also call this directly to pre-validate a config before passing it to the constructor.

Errors

Returns ClientError::InvalidArgument when any field is zero or out-of-range.

Trait Implementations

impl Clone for ClientConfig

fn clone(&self) -> ClientConfig

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for ClientConfig

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for ClientConfig

fn default() -> Self

Returns the “default value” for a type.

impl Eq for ClientConfig

impl PartialEq for ClientConfig

fn eq(&self, other: &ClientConfig) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl StructuralPartialEq for ClientConfig