Static Decoding of Signed Extensions: Simple Approach (#1235)

* skeleton commit * signed extension decoding * fix some minor things * make api more similar to Extrinsics * defer decoding of signed extensions * fix byte slices * add test for nonce signed extension * adjust test and extend for tip * clippy * support both ChargeTransactionPayment and ChargeAssetTxPayment * address PR comments * Extend lifetimes, expose pub structs, remove as_type * add signed extensions to block subscribing example * add Decoded type * fix merging bug and tests * add decoded type in CustomSignedExtension * fix minor issues, extend test * cargo fmt differences * remove the `decoded` function * new as_signed_extra fn, do not expose as_type anymore * fix Result-Option order, simplify obtaining Nonce * tx: Remove `wait_for_in_block` helper method (#1237) Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * Update smoldot to 0.12 (#1212) * Update lightclient Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * testing: Fix typo Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * testing: Update cargo.toml Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * lightclient: Add tracing logs to improve debugging Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * lightclient: Add socket buffers module for `PlatformRef` Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * lightclient: Update `SubxtPlatform` Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * cargo: Add lightclient dependencies Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * Update cargo.lock of wasm tests Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * lightclient: Add constant for with-buffer module Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * lightclient: Replace rand crate with getrandom Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * example: Update cargo lock file Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> * examples: Update deps Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> --------- Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> Co-authored-by: Tadeo Hepperle <62739623+tadeohepperle@users.noreply.github.com> * ChargeAssetTxPayment: support providing u32 or MultiLocation in default impl (#1227) * Asset Id in Config trait * add example configuring the config * fmt * fix Default trait bound * merge examples, fix default again * adjust config in examples * Update subxt/src/config/mod.rs Co-authored-by: James Wilson <james@jsdw.me> --------- Co-authored-by: James Wilson <james@jsdw.me> * generic AssetId * fix generics * fmt --------- Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io> Co-authored-by: James Wilson <james@jsdw.me> Co-authored-by: Alexandru Vasile <60601340+lexnv@users.noreply.github.com>
2026-06-11 22:21:07 +00:00 · 2023-11-10 18:32:58 +01:00
parent e7c1f73429
commit 56d0cdae78
7 changed files with 150 additions and 44 deletions
@@ -12,9 +12,13 @@ use crate::{
    Metadata,
 };

+use crate::config::signed_extensions::{
+    ChargeAssetTxPayment, ChargeTransactionPayment, CheckNonce,
+};
+use crate::config::SignedExtension;
 use crate::dynamic::DecodedValue;
 use crate::utils::strip_compact_prefix;
-use codec::{Compact, Decode};
+use codec::Decode;
 use derivative::Derivative;
 use scale_decode::{DecodeAsFields, DecodeAsType};

@@ -366,12 +370,13 @@ where
    }

    /// Returns `None` if the extrinsic is not signed.
-    pub fn signed_extensions(&self) -> Option<ExtrinsicSignedExtensions<'_>> {
+    pub fn signed_extensions(&self) -> Option<ExtrinsicSignedExtensions<'_, T>> {
        let signed = self.signed_details.as_ref()?;
        let extra_bytes = &self.bytes[signed.signature_end_idx..signed.extra_end_idx];
        Some(ExtrinsicSignedExtensions {
            bytes: extra_bytes,
            metadata: &self.metadata,
+            _marker: std::marker::PhantomData,
        })
    }

@@ -605,21 +610,22 @@ impl<T: Config> ExtrinsicEvents<T> {

 /// The signed extensions of an extrinsic.
 #[derive(Debug, Clone)]
-pub struct ExtrinsicSignedExtensions<'a> {
+pub struct ExtrinsicSignedExtensions<'a, T: Config> {
    bytes: &'a [u8],
    metadata: &'a Metadata,
+    _marker: std::marker::PhantomData<T>,
 }

-impl<'a> ExtrinsicSignedExtensions<'a> {
+impl<'a, T: Config> ExtrinsicSignedExtensions<'a, T> {
    /// Returns an iterator over each of the signed extension details of the extrinsic.
    /// If the decoding of any signed extension fails, an error item is yielded and the iterator stops.
-    pub fn iter(&self) -> impl Iterator<Item = Result<ExtrinsicSignedExtension<'a>, Error>> {
+    pub fn iter(&self) -> impl Iterator<Item = Result<ExtrinsicSignedExtension<T>, Error>> {
        let signed_extension_types = self.metadata.extrinsic().signed_extensions();
        let num_signed_extensions = signed_extension_types.len();
        let bytes = self.bytes;
-        let metadata = self.metadata;
        let mut index = 0;
        let mut byte_start_idx = 0;
+        let metadata = &self.metadata;

        std::iter::from_fn(move || {
            if index == num_signed_extensions {
@@ -649,49 +655,69 @@ impl<'a> ExtrinsicSignedExtensions<'a> {
                ty_id,
                identifier: extension.identifier(),
                metadata,
+                _marker: std::marker::PhantomData,
            }))
        })
    }

+    fn find_by_name(&self, name: &str) -> Option<ExtrinsicSignedExtension<'_, T>> {
+        let signed_extension = self
+            .iter()
+            .find_map(|e| e.ok().filter(|e| e.name() == name))?;
+        Some(signed_extension)
+    }
+
+    /// Searches through all signed extensions to find a specific one.
+    /// If the Signed Extension is not found `Ok(None)` is returned.
+    /// If the Signed Extension is found but decoding failed `Err(_)` is returned.
+    pub fn find<S: SignedExtension<T>>(&self) -> Result<Option<S::Decoded>, Error> {
+        self.find_by_name(S::NAME)
+            .map(|s| {
+                s.as_signed_extra::<S>().map(|e| {
+                    e.expect("signed extra name is correct, because it was found before; qed.")
+                })
+            })
+            .transpose()
+    }
+
    /// The tip of an extrinsic, extracted from the ChargeTransactionPayment or ChargeAssetTxPayment
    /// signed extension, depending on which is present.
    ///
    /// Returns `None` if  `tip` was not found or decoding failed.
    pub fn tip(&self) -> Option<u128> {
-        let tip = self.iter().find_map(|e| {
-            e.ok().filter(|e| {
-                e.name() == "ChargeTransactionPayment" || e.name() == "ChargeAssetTxPayment"
+        // Note: the overhead of iterating twice should be negligible.
+        self.find::<ChargeTransactionPayment>()
+            .ok()
+            .flatten()
+            .map(|e| e.tip())
+            .or_else(|| {
+                self.find::<ChargeAssetTxPayment<T>>()
+                    .ok()
+                    .flatten()
+                    .map(|e| e.tip())
            })
-        })?;
-
-        // Note: ChargeAssetTxPayment might have addition information in it (asset_id).
-        // But both should start with a compact encoded u128, so this decoding is fine.
-        let tip = Compact::<u128>::decode(&mut tip.bytes()).ok()?.0;
-        Some(tip)
    }

    /// The nonce of the account that submitted the extrinsic, extracted from the CheckNonce signed extension.
    ///
    /// Returns `None` if `nonce` was not found or decoding failed.
    pub fn nonce(&self) -> Option<u64> {
-        let nonce = self
-            .iter()
-            .find_map(|e| e.ok().filter(|e| e.name() == "CheckNonce"))?;
-        let nonce = Compact::<u64>::decode(&mut nonce.bytes()).ok()?.0;
+        let nonce = self.find::<CheckNonce>().ok()??.0;
        Some(nonce)
    }
 }

 /// A single signed extension
 #[derive(Debug, Clone)]
-pub struct ExtrinsicSignedExtension<'a> {
+pub struct ExtrinsicSignedExtension<'a, T: Config> {
    bytes: &'a [u8],
    ty_id: u32,
    identifier: &'a str,
    metadata: &'a Metadata,
+    _marker: std::marker::PhantomData<T>,
 }

-impl<'a> ExtrinsicSignedExtension<'a> {
+impl<'a, T: Config> ExtrinsicSignedExtension<'a, T> {
    /// The bytes representing this signed extension.
    pub fn bytes(&self) -> &'a [u8] {
        self.bytes
@@ -709,11 +735,23 @@ impl<'a> ExtrinsicSignedExtension<'a> {

    /// Signed Extension as a [`scale_value::Value`]
    pub fn value(&self) -> Result<DecodedValue, Error> {
-        let value =
-            DecodedValue::decode_as_type(&mut &self.bytes[..], self.ty_id, self.metadata.types())?;
+        self.as_type()
+    }

+    /// Decodes the `extra` bytes of this Signed Extension into a static type.
+    fn as_type<E: DecodeAsType>(&self) -> Result<E, Error> {
+        let value = E::decode_as_type(&mut &self.bytes[..], self.ty_id, self.metadata.types())?;
        Ok(value)
    }
+
+    /// Decodes the `extra` bytes of this Signed Extension into its associated `Decoded` type.
+    /// Returns `Ok(None)` if the identitfier of this Signed Extension object does not line up with the `NAME` constant of the provided Signed Extension type.
+    pub fn as_signed_extra<S: SignedExtension<T>>(&self) -> Result<Option<S::Decoded>, Error> {
+        if self.identifier != S::NAME {
+            return Ok(None);
+        }
+        self.as_type::<S::Decoded>().map(Some)
+    }
 }

 #[cfg(test)]