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use crate::error::{Error, Result};
use crate::link::reconcile::StoredRewrite;
use crate::protocol::command::rewrite_payload;
use crate::protocol::opcode::{
MAX_PAYLOAD, Q_REWRITE, Q_REWRITE_ENTRY, REWRITE_MATCH_MAX, REWRITE_MAX_ENTRIES,
};
use crate::protocol::{FrameType, Resp, parse_resp};
use crate::types::rewrite::{REWRITE_CLEAR_ID, rewrite_entry_from_payload};
use crate::types::{Direction, RewriteAction, RewriteClass, RewriteRule, RewriteTable};
use super::Device;
impl Device {
/// `REWRITE` (§3.14): install (add or overwrite) one rewrite rule.
///
/// The on-box rewrite table matches traffic in flight and rewrites, answers, refuses or drops it
/// per the rule's [`action`](RewriteRule::action). A rule is keyed by
/// `(class, id, direction, match, mask)`; setting one whose key exists overwrites it. Rules are
/// session state, re-asserted on reconnect and held alive by the keepalive exactly like a
/// [`lock`](Device::lock) or a catch subscription, and cleared on control-PC silence,
/// [`reset`](Device::reset), a re-clone, or the opt-in going off.
///
/// Gated on [`allow_imperfect_clones`](Device::allow_imperfect_clones): with the opt-in off this
/// returns [`Error::ImperfectRequired`](crate::Error::ImperfectRequired). The rule's `match` and
/// `mask` must be the same length ([`Error::RewriteMaskLength`](crate::Error::RewriteMaskLength)),
/// its `action` must be valid for its `class`
/// ([`Error::RewriteActionClass`](crate::Error::RewriteActionClass)), and its `direction` must not
/// be bearing-relative ([`Error::RelativeDirection`](crate::Error::RelativeDirection)). Delivery is
/// fire-and-forget: [`query_rewrite`](Device::query_rewrite) confirms what the box actually holds.
pub fn set_rewrite(&self, rule: &RewriteRule) -> Result<()> {
validate_rule(rule)?;
self.require_imperfect()?;
self.set_rewrite_checked(rule)
}
/// The capacity check and the send under ONE re-assert guard, so two threads at the last slot
/// cannot both pass it, and so the async wrapper (which does its own opt-in check) gets the check
/// too. Taking the guard here and again in `set_rewrite_send` would deadlock: it is not reentrant.
pub(crate) fn set_rewrite_checked(&self, rule: &RewriteRule) -> Result<()> {
let _serial = self.link.reassert_guard();
{
let d = self.link.desired().lock();
if !d.holds_rewrite(&to_stored(rule).key()) && d.rewrite_count() >= REWRITE_MAX_ENTRIES
{
return Err(Error::RewriteTableFull {
limit: REWRITE_MAX_ENTRIES,
});
}
}
self.set_rewrite_send_locked(rule)
}
/// The validated `REWRITE` set with no opt-in pre-check, so the async wrapper can gate on the async
/// query path. Records the rule for reconnect-replay, then rolls back if the frame never went out.
/// The caller holds the re-assert guard, which serialises this against the keepalive/reconnect
/// re-assert so a concurrent remove/clear cannot interleave. Recorded before the write so a
/// reconnect racing it still replays the rule, and rolled back when the frame never went out.
fn set_rewrite_send_locked(&self, rule: &RewriteRule) -> Result<()> {
let stored = to_stored(rule);
let undo = self.link.desired().lock().apply_rewrite(stored);
let sent = self.link.send(
FrameType::Rewrite,
&rewrite_payload(
rule.class.as_u8(),
rule.id,
rule.direction.as_u8(),
1,
rule.action.as_u8(),
rule.offset,
&rule.match_bytes,
&rule.mask,
&rule.payload,
),
);
if sent.is_err() {
self.link.desired().lock().restore_rewrite(undo);
}
sent
}
/// `REWRITE` remove (§3.14): drop the rule keyed by this rule's `(class, id, direction, match,
/// mask)`. The rule's action and payload are ignored. A no-op on the box if no such rule is held.
pub fn remove_rewrite(&self, rule: &RewriteRule) -> Result<()> {
if rule.match_bytes.len() != rule.mask.len() {
return Err(Error::RewriteMaskLength {
match_len: rule.match_bytes.len(),
mask_len: rule.mask.len(),
});
}
let key = to_stored(rule).key();
// Serialise the removal and its send against the re-assert, or a keepalive tick could re-send a
// stale add after the remove and leave the rule live on the box.
let _serial = self.link.reassert_guard();
let undo = self.link.desired().lock().remove_rewrite(key);
let sent = self.link.send(
FrameType::Rewrite,
&rewrite_payload(
rule.class.as_u8(),
rule.id,
rule.direction.as_u8(),
0,
rule.action.as_u8(),
rule.offset,
&rule.match_bytes,
&rule.mask,
&[],
),
);
if sent.is_err() {
self.link.desired().lock().restore_rewrite(undo);
}
sent
}
/// `REWRITE` clear (§3.14): drop the whole rewrite table (the `class 0xFF, id 0xFFFF, state 0`
/// blanket). Always clears the crate's held rules, whatever the opt-in.
pub fn clear_rewrite(&self) -> Result<()> {
// Serialise the clear and its send against the re-assert, and snapshot the rules first so a
// failed send restores them (the box still holds them), keeping DesiredState in step.
let _serial = self.link.reassert_guard();
let held = {
let mut d = self.link.desired().lock();
let held = d.held_rewrites();
d.clear_rewrites();
held
};
let sent = self.link.send(
FrameType::Rewrite,
&rewrite_payload(
RewriteClass::Any.as_u8(),
REWRITE_CLEAR_ID,
Direction::Both.as_u8(),
0,
0,
0,
&[],
&[],
&[],
),
);
if sent.is_err() {
let mut d = self.link.desired().lock();
for r in held {
d.apply_rewrite(r);
}
}
sent
}
/// `QUERY(REWRITE)` → [`RewriteTable`] (§4.17): the whole table's summary (flags, generation, and a
/// row per rule without its match/mask/payload bytes). Read one rule in full with
/// [`query_rewrite_entry`](Device::query_rewrite_entry).
pub fn query_rewrite(&self) -> Result<RewriteTable> {
let payload = self.link.query(Q_REWRITE)?;
match parse_resp(&payload) {
Some(Resp::Rewrite(t)) => Ok(t),
_ => Err(Error::NoReply),
}
}
/// `QUERY(REWRITE_ENTRY, index)` → [`RewriteRule`] (§4.17): one rule in full, in the shape
/// [`set_rewrite`](Device::set_rewrite) takes, so a read rule replays as a set. `index` is the row
/// in the [`query_rewrite`](Device::query_rewrite) summary.
pub fn query_rewrite_entry(&self, index: u8) -> Result<RewriteRule> {
let payload = self.link.query_indexed(Q_REWRITE_ENTRY, index)?;
rewrite_entry_from_payload(&payload).ok_or(Error::NoReply)
}
}
pub(crate) fn to_stored(rule: &RewriteRule) -> StoredRewrite {
StoredRewrite {
class: rule.class.as_u8(),
id: rule.id,
direction: rule.direction.as_u8(),
action: rule.action.as_u8(),
offset: rule.offset,
match_bytes: rule.match_bytes.clone(),
mask: rule.mask.clone(),
payload: rule.payload.clone(),
}
}
pub(crate) fn validate_rule(rule: &RewriteRule) -> Result<()> {
if rule.match_bytes.len() != rule.mask.len() {
return Err(Error::RewriteMaskLength {
match_len: rule.match_bytes.len(),
mask_len: rule.mask.len(),
});
}
if rule.match_bytes.len() > REWRITE_MATCH_MAX {
return Err(Error::RewriteMatchTooLong {
len: rule.match_bytes.len(),
limit: REWRITE_MATCH_MAX,
});
}
// REWRITE's direction byte is Both/Positive/Negative only; the box rejects the bearing-relative
// pair by range, so surface it here rather than sending a frame the box drops.
if rule.direction.is_relative() {
return Err(Error::RelativeDirection {
direction: rule.direction,
what: "rewrite rule",
});
}
if !rule.action.is_valid_for(rule.class) {
return Err(Error::RewriteActionClass {
action: rule.action,
class: rule.class,
});
}
// The box refuses a rule its own read-back reply cannot carry: that reply's header is two bytes
// wider than the command's, so a rule can fit the frame it is sent in and still be refused.
const ENTRY_HDR: usize = 11;
let room = MAX_PAYLOAD - ENTRY_HDR - 2 * rule.match_bytes.len();
if rule.payload.len() > room {
return Err(Error::RewritePayloadTooLarge {
action: rule.action,
class: rule.class,
len: rule.payload.len(),
offset: rule.offset as usize,
cap: room,
});
}
// Mirror the box's head-cap admission (rewrite_tab.h): a report surface holds 64 bytes and a
// control image 8+2048, so a rule whose payload cannot land is refused there. Reject it here
// rather than hold a rule DesiredState keeps but the box drops.
const HEAD_REPORT: usize = 64;
const HEAD_CONTROL: usize = 8 + 2048;
let plen = rule.payload.len();
let off = rule.offset as usize;
let report_cap = if rule.class == RewriteClass::Control {
HEAD_CONTROL
} else {
HEAD_REPORT
};
let (over, cap) = match rule.action {
RewriteAction::Patch | RewriteAction::ReplyPatch => (off + plen > report_cap, report_cap),
RewriteAction::Replace => (plen > report_cap, report_cap),
RewriteAction::Answer | RewriteAction::ReplyReplace => (plen > HEAD_CONTROL, HEAD_CONTROL),
_ => (false, 0),
};
if over {
return Err(Error::RewritePayloadTooLarge {
action: rule.action,
class: rule.class,
len: plen,
offset: off,
cap,
});
}
Ok(())
}