Browser extension signing example (#1067)

* routing and signing example

* cliipy fix

* submitting extrinsics

* change order of lines

* Skip call variants if there aren't any (#980)

Co-authored-by: Niklas Adolfsson <niklasadolfsson1@gmail.com>

* Tidy up some metadata accessing (#978)

* Reduce some repetition when obtaining metadata pallets/runtime_traits

* make them pub

* fix docs and clippy

* Bump tokio from 1.28.1 to 1.28.2 (#984)

Bumps [tokio](https://github.com/tokio-rs/tokio) from 1.28.1 to 1.28.2.
- [Release notes](https://github.com/tokio-rs/tokio/releases)
- [Commits](https://github.com/tokio-rs/tokio/compare/tokio-1.28.1...tokio-1.28.2)

---
updated-dependencies:
- dependency-name: tokio
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

* Bump regex from 1.8.2 to 1.8.3 (#986)

Bumps [regex](https://github.com/rust-lang/regex) from 1.8.2 to 1.8.3.
- [Release notes](https://github.com/rust-lang/regex/releases)
- [Changelog](https://github.com/rust-lang/regex/blob/master/CHANGELOG.md)
- [Commits](https://github.com/rust-lang/regex/compare/1.8.2...1.8.3)

---
updated-dependencies:
- dependency-name: regex
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

* Bump quote from 1.0.27 to 1.0.28 (#983)

Bumps [quote](https://github.com/dtolnay/quote) from 1.0.27 to 1.0.28.
- [Release notes](https://github.com/dtolnay/quote/releases)
- [Commits](https://github.com/dtolnay/quote/compare/1.0.27...1.0.28)

---
updated-dependencies:
- dependency-name: quote
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

* Bump proc-macro2 from 1.0.58 to 1.0.59 (#985)

Bumps [proc-macro2](https://github.com/dtolnay/proc-macro2) from 1.0.58 to 1.0.59.
- [Release notes](https://github.com/dtolnay/proc-macro2/releases)
- [Commits](https://github.com/dtolnay/proc-macro2/compare/1.0.58...1.0.59)

---
updated-dependencies:
- dependency-name: proc-macro2
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

* restrict sign_with_address_and_signature interface (#988)

* changing js bridge

* dryrunresult ok

* submitting extrinsic working

* tiny up code and ui

* formatting

* remove todos

* support tip and mortality

* Prevent bug when reusing type ids in hashing (#1075)

* practice TDD

* implement a hashmap 2-phases approach

* use nicer types

* add test for cache filling

* adjust test

---------

Co-authored-by: James Wilson <james@jsdw.me>

* small adjustment

* Merge branch 'master' into tadeo-hepperle-browser-extension-signing-example

* fix lock file

* tell users how to add Alice account to run signing example

* adjust to PR comments

* fmt

---------

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: James Wilson <james@jsdw.me>
Co-authored-by: Niklas Adolfsson <niklasadolfsson1@gmail.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

examples/wasm-example/src/services.rs

@@ -1,10 +1,19 @@
+use anyhow::anyhow;
 use futures::StreamExt;
+use js_sys::Promise;
+use serde::{Deserialize, Serialize};
+use serde_json::json;
 use std::fmt::Write;
+use subxt::ext::codec::Encode;
+use subxt::tx::PartialExtrinsic;
 use subxt::{self, OnlineClient, PolkadotConfig};
+use subxt::utils::AccountId32;
+use wasm_bindgen::prelude::*;
+use wasm_bindgen_futures::JsFuture;
 use yew::{AttrValue, Callback};
 
 #[subxt::subxt(runtime_metadata_path = "../../artifacts/polkadot_metadata_small.scale")]
-mod polkadot {}
+pub mod polkadot {}
 
 pub(crate) async fn fetch_constant_block_length() -> Result<String, subxt::Error> {
     let api = OnlineClient::<PolkadotConfig>::new().await?;
@@ -71,3 +80,105 @@ pub(crate) async fn subscribe_to_finalized_blocks(
     }
     Ok(())
 }
+
+#[wasm_bindgen]
+extern "C" {
+    #[wasm_bindgen(js_name = getAccounts)]
+    pub fn js_get_accounts() -> Promise;
+    #[wasm_bindgen(js_name = signPayload)]
+    pub fn js_sign_payload(payload: String, source: String, address: String) -> Promise;
+}
+
+/// DTO to communicate with JavaScript
+#[derive(Clone, Debug, Serialize, Deserialize)]
+pub struct Account {
+    /// account name
+    pub name: String,
+    /// name of the browser extension
+    pub source: String,
+    /// the signature type, e.g. "sr25519" or "ed25519"
+    pub ty: String,
+    /// ss58 formatted address as string. Can be converted into AccountId32 via it's FromStr implementation.
+    pub address: String,
+}
+
+pub async fn get_accounts() -> Result<Vec<Account>, anyhow::Error> {
+    let result = JsFuture::from(js_get_accounts())
+        .await
+        .map_err(|js_err| anyhow!("{js_err:?}"))?;
+    let accounts_str = result
+        .as_string()
+        .ok_or(anyhow!("Error converting JsValue into String"))?;
+    let accounts: Vec<Account> = serde_json::from_str(&accounts_str)?;
+    Ok(accounts)
+}
+
+fn to_hex(bytes: impl AsRef<[u8]>) -> String {
+    format!("0x{}", hex::encode(bytes.as_ref()))
+}
+
+fn encode_to_hex<E: Encode>(input: &E) -> String {
+    format!("0x{}", hex::encode(input.encode()))
+}
+
+/// this is used because numeric types (e.g. u32) are encoded as little-endian via scale (e.g. 9430 -> d6240000)
+/// while we need a big-endian representation for the json (e.g. 9430 -> 000024d6).
+fn encode_to_hex_reverse<E: Encode>(input: &E) -> String {
+    let mut bytes = input.encode();
+    bytes.reverse();
+    format!("0x{}", hex::encode(bytes))
+}
+
+
+/// communicates with JavaScript to obtain a signature for the `partial_extrinsic` via a browser extension (e.g. polkadot-js or Talisman)
+///
+/// Some parameters are hard-coded here and not taken from the partial_extrinsic itself (mortality_checkpoint, era, tip).
+pub async fn extension_signature_for_partial_extrinsic(
+    partial_extrinsic: &PartialExtrinsic<PolkadotConfig, OnlineClient<PolkadotConfig>>,
+    api: &OnlineClient<PolkadotConfig>,
+    account_id: &AccountId32,
+    account_source: String,
+    account_address: String,
+) -> Result<Vec<u8>, anyhow::Error> {
+    let spec_version = encode_to_hex_reverse(&api.runtime_version().spec_version);
+    let transaction_version = encode_to_hex_reverse(&api.runtime_version().transaction_version);
+    let mortality_checkpoint = encode_to_hex(&api.genesis_hash());
+    let era = encode_to_hex(&subxt::config::extrinsic_params::Era::Immortal);
+    let genesis_hash = encode_to_hex(&api.genesis_hash());
+    let method = to_hex(partial_extrinsic.call_data());
+    let nonce = api.tx().account_nonce(account_id).await?;
+    let nonce = encode_to_hex_reverse(&nonce);
+    let signed_extensions: Vec<String> = api
+        .metadata()
+        .extrinsic()
+        .signed_extensions()
+        .iter()
+        .map(|e| e.identifier().to_string())
+        .collect();
+    let tip = encode_to_hex(&subxt::config::polkadot::PlainTip::new(0));
+
+    let payload = json!({
+        "specVersion": spec_version,
+        "transactionVersion": transaction_version,
+        "address": account_address,
+        "blockHash": mortality_checkpoint,
+        "blockNumber": "0x00000000",
+        "era": era,
+        "genesisHash": genesis_hash,
+        "method": method,
+        "nonce": nonce,
+        "signedExtensions": signed_extensions,
+        "tip": tip,
+        "version": 4,
+    });
+
+    let payload = payload.to_string();
+    let result = JsFuture::from(js_sign_payload(payload, account_source, account_address))
+        .await
+        .map_err(|js_err| anyhow!("{js_err:?}"))?;
+    let signature = result
+        .as_string()
+        .ok_or(anyhow!("Error converting JsValue into String"))?;
+    let signature = hex::decode(&signature[2..])?;
+    Ok(signature)
+}