lightningd: remove support for long-deprecated old-style feerate responses.
What the developer wrote
Authored by Rusty Russell
lightningd: remove support for long-deprecated old-style feerate responses.
This was supposed to be removed in v24.05. Finally remove it now.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Changelog-Removed: lightningd: `estimatefeesv1` support for older bcli plugins (deprecated v23.05, disabled by default v24.05).
What changed, and why it matters
This commit removes old, deprecated fee-estimate response handling from Core Lightning's Bitcoin backend plugin interface. It was already disabled by default in v24.05 and was scheduled for removal. The change makes the code stricter: if a plugin still returns the old format, Core Lightning will now log an error and stop rather than silently accepting it. This is a cleanup of technical debt, not a fix for an active security vulnerability.
No urgent action. Operators using custom bcli plugins should ensure they emit the modern estimatefees response format (feerate_floor + feerates object). This is a normal deprecation removal; review plugin compatibility before upgrading.
Security signals we found
Removal of deprecated protocol/format fallback reduces attack surface
Error path now terminates instead of continuing with parsed deprecated data
No input validation bypass or memory safety bug evident in diff
Evidence from the diff
The patch deletes parse_deprecated_feerates() and the fallback path in estimatefees_callback() that accepted the pre-v23.05 ‘estimatefeesv1’ response shape (fields like opening, mutual_close, unilateral_close, max_acceptable). It also marks bitcoin_plugin_error() as NORETURN. From now on, estimatefees responses must include feerate_floor and the modern feerates object; missing feerate_floor triggers bitcoin_plugin_error(). The deprecation cycle (deprecated v23.05, disabled by default v24.05) was already documented.
Changed components
lightningd/bitcoind.cestimatefees callbackBitcoin backend plugin interfaceInspect captured patch +8 / −79
diff --git a/lightningd/bitcoind.c b/lightningd/bitcoind.c
index a7e9b876..58b7b092 100644
--- a/lightningd/bitcoind.c
+++ b/lightningd/bitcoind.c
@@ -93,9 +93,10 @@ void bitcoind_check_commands(struct bitcoind *bitcoind)
}
/* Our Bitcoin backend plugin gave us a bad response. We can't recover. */
-static void bitcoin_plugin_error(struct bitcoind *bitcoind, const char *buf,
- const jsmntok_t *toks, const char *method,
- const char *fmt, ...)
+static void NORETURN
+bitcoin_plugin_error(struct bitcoind *bitcoind, const char *buf,
+ const jsmntok_t *toks, const char *method,
+ const char *fmt, ...)
{
va_list ap;
char *reason;
@@ -137,19 +138,7 @@ static void bitcoin_plugin_send(struct bitcoind *bitcoind,
* - `min` is the minimum acceptable feerate
* - `max` is the maximum acceptable feerate
*
- * Plugin response (deprecated):
- * {
- * "opening": <sat per kVB>,
- * "mutual_close": <sat per kVB>,
- * "unilateral_close": <sat per kVB>,
- * "delayed_to_us": <sat per kVB>,
- * "htlc_resolution": <sat per kVB>,
- * "penalty": <sat per kVB>,
- * "min_acceptable": <sat per kVB>,
- * "max_acceptable": <sat per kVB>,
- * }
- *
- * Plugin response (modern):
+ * Plugin response:
* {
* "feerate_floor": <sat per kVB>,
* "feerates": {
@@ -230,55 +219,6 @@ static struct feerate_est *parse_feerate_ranges(const tal_t *ctx,
return rates;
}
-static struct feerate_est *parse_deprecated_feerates(const tal_t *ctx,
- struct bitcoind *bitcoind,
- const char *buf,
- const jsmntok_t *toks)
-{
- struct feerate_est *rates = tal_arr(ctx, struct feerate_est, 0);
- struct oldstyle {
- const char *name;
- size_t blockcount;
- size_t multiplier;
- } oldstyles[] = { { "max_acceptable", 2, 10 },
- { "unilateral_close", 6, 1 },
- { "opening", 12, 1 },
- { "mutual_close", 100, 1 } };
-
- for (size_t i = 0; i < ARRAY_SIZE(oldstyles); i++) {
- const jsmntok_t *feeratetok;
- struct feerate_est rate;
-
- feeratetok = json_get_member(buf, toks, oldstyles[i].name);
- if (!feeratetok) {
- bitcoin_plugin_error(bitcoind, buf, toks,
- "estimatefees",
- "missing '%s' field",
- oldstyles[i].name);
- }
- if (!json_to_u32(buf, feeratetok, &rate.rate)) {
- if (chainparams->testnet)
- log_debug(bitcoind->log,
- "Unable to estimate %s fees",
- oldstyles[i].name);
- else
- log_unusual(bitcoind->log,
- "Unable to estimate %s fees",
- oldstyles[i].name);
- continue;
- }
-
- if (rate.rate == 0)
- continue;
-
- /* Cancel out the 10x multiplier on max_acceptable */
- rate.rate /= oldstyles[i].multiplier;
- rate.blockcount = oldstyles[i].blockcount;
- tal_arr_expand(&rates, rate);
- }
- return rates;
-}
-
static void estimatefees_callback(const char *buf, const jsmntok_t *toks,
const jsmntok_t *idtok,
struct estimatefee_call *call)
@@ -302,20 +242,9 @@ static void estimatefees_callback(const char *buf, const jsmntok_t *toks,
"feerates"),
&floor);
} else {
- if (!lightningd_deprecated_in_ok(call->bitcoind->ld,
- call->bitcoind->ld->log,
- call->bitcoind->ld->deprecated_ok,
- "estimatefeesv1", NULL,
- "v23.05", "v24.05",
- NULL)) {
- bitcoin_plugin_error(call->bitcoind, buf, resulttok,
- "estimatefees",
- "missing feerate_floor field");
- }
-
- feerates = parse_deprecated_feerates(call, call->bitcoind,
- buf, resulttok);
- floor = feerate_from_style(FEERATE_FLOOR, FEERATE_PER_KSIPA);
+ bitcoin_plugin_error(call->bitcoind, buf, resulttok,
+ "estimatefees",
+ "missing feerate_floor field");
}
/* Convert to perkw */
Why this scored 23/100
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