Add decode command for event, message and constructor data decoding

src/cmd/decode.rs

@@ -0,0 +1,65 @@
+// Copyright 2018-2020 Parity Technologies (UK) Ltd.
+// This file is part of cargo-contract.
+//
+// cargo-contract is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// cargo-contract is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with cargo-contract.  If not, see <http://www.gnu.org/licenses/>.
+
+use crate::{
+    cmd::extrinsics::{load_metadata, ContractMessageTranscoder},
+    util::decode_hex,
+    DEFAULT_KEY_COL_WIDTH,
+};
+use anyhow::{Context, Result};
+use colored::Colorize as _;
+
+#[derive(Debug, Clone, clap::Args)]
+#[clap(name = "decode", about = "Decode input_data for a contract")]
+pub struct DecodeCommand {
+    /// Type of data
+    #[clap(arg_enum, short, long)]
+    r#type: DataType,
+    /// The data to decode
+    #[clap(long)]
+    data: String,
+}
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord, clap::ArgEnum)]
+enum DataType {
+    Event,
+    Message,
+}
+
+impl DecodeCommand {
+    pub fn run(&self) -> Result<()> {
+        let (_, contract_metadata) = load_metadata(None)?;
+        let transcoder = ContractMessageTranscoder::new(&contract_metadata);
+
+        const ERR_MSG: &str = "Failed to decode specified data as a hex value";
+        let decoded_data = match self.r#type {
+            DataType::Event => {
+                transcoder.decode_contract_event(&mut &decode_hex(&self.data).context(ERR_MSG)?[..])
+            }
+            DataType::Message => transcoder
+                .decode_contract_message(&mut &decode_hex(&self.data).context(ERR_MSG)?[..]),
+        };
+
+        println!(
+            "{:>width$} {:?}",
+            "Decoded data:".bright_green().bold(),
+            decoded_data,
+            width = DEFAULT_KEY_COL_WIDTH
+        );
+
+        Ok(())
+    }
+}

src/cmd/extrinsics/call.rs

@@ -56,6 +56,8 @@ impl CallCommand {
         let (_, contract_metadata) = load_metadata(self.extrinsic_opts.manifest_path.as_ref())?;
         let transcoder = ContractMessageTranscoder::new(&contract_metadata);
         let call_data = transcoder.encode(&self.message, &self.args)?;
+        log::debug!("message data: {:?}", hex::encode(&call_data));
+
         let signer = super::pair_signer(self.extrinsic_opts.signer()?);
 
         async_std::task::block_on(async {

src/cmd/extrinsics/events.rs

@@ -66,6 +66,7 @@ pub fn display_events(
             if <ContractEmitted as Event>::is_event(&event.pallet, &event.variant)
                 && field.name() == Some(&"data".to_string())
             {
+                log::debug!("event data: {:?}", hex::encode(&event_data));
                 let contract_event = transcoder.decode_contract_event(event_data)?;
                 maybe_println!(
                     verbosity,

src/cmd/extrinsics/mod.rs

@@ -28,7 +28,7 @@ mod integration_tests;
 use anyhow::{anyhow, Context, Result};
 use std::{fs::File, path::PathBuf};
 
-use self::{events::display_events, transcode::ContractMessageTranscoder};
+use self::events::display_events;
 use crate::{
     crate_metadata::CrateMetadata, name_value_println, workspace::ManifestPath, Verbosity,
     VerbosityFlags,
@@ -37,6 +37,7 @@ use pallet_contracts_primitives::ContractResult;
 use sp_core::{crypto::Pair, sr25519};
 use subxt::{Config, DefaultConfig};
 
+pub use self::transcode::ContractMessageTranscoder;
 pub use call::CallCommand;
 pub use instantiate::InstantiateCommand;
 pub use runtime_api::api::{DispatchError as RuntimeDispatchError, Event as RuntimeEvent};

src/cmd/extrinsics/transcode/mod.rs

@@ -175,7 +175,6 @@ impl<'a> ContractMessageTranscoder<'a> {
         // data is an encoded `Vec<u8>` so is prepended with its length `Compact<u32>`, which we
         // ignore because the structure of the event data is known for decoding.
         let _len = <Compact<u32>>::decode(data)?;
-
         let variant_index = data.read_byte()?;
         let event_spec = self
             .metadata
@@ -203,6 +202,37 @@ impl<'a> ContractMessageTranscoder<'a> {
         Ok(Value::Map(map))
     }
 
+    pub fn decode_contract_message(&self, data: &mut &[u8]) -> Result<Value> {
+        let mut msg_selector = [0u8; 4];
+        data.read(&mut msg_selector)?;
+        let msg_spec = self
+            .metadata
+            .spec()
+            .messages()
+            .iter()
+            .filter(|x| msg_selector == x.selector().to_bytes())
+            .next()
+            .ok_or_else(|| {
+                anyhow::anyhow!(
+                    "Message with selector {} not found in contract metadata",
+                    hex::encode(&msg_selector)
+                )
+            })?;
+        log::debug!("decoding contract message '{}'", msg_spec.label());
+
+        let mut args = Vec::new();
+        for arg in msg_spec.args() {
+            let name = arg.label().to_string();
+            let value = self.transcoder.decode(arg.ty().ty().id(), data)?;
+            args.push((Value::String(name), value));
+        }
+
+        let name = msg_spec.label().to_string();
+        let map = Map::new(Some(&name), args.into_iter().collect());
+
+        Ok(Value::Map(map))
+    }
+
     pub fn decode_return(&self, name: &str, data: &mut &[u8]) -> Result<Value> {
         let msg_spec = self
             .find_message_spec(name)
@@ -391,4 +421,15 @@ mod tests {
 
         Ok(())
     }
+
+    #[test]
+    fn decode_contract_message() -> Result<()> {
+        let metadata = generate_metadata();
+        let transcoder = ContractMessageTranscoder::new(&metadata);
+
+        let encoded_bytes = hex::decode("633aa551").unwrap();
+        let _ = transcoder.decode_contract_message(&mut &encoded_bytes[..])?;
+
+        Ok(())
+    }
 }

src/cmd/mod.rs

@@ -15,12 +15,14 @@
 // along with cargo-contract.  If not, see <http://www.gnu.org/licenses/>.
 
 pub mod build;
+pub mod decode;
 pub mod metadata;
 pub mod new;
 pub mod test;
 
 pub(crate) use self::{
     build::{BuildCommand, CheckCommand},
+    decode::DecodeCommand,
     test::TestCommand,
 };
 mod extrinsics;

src/main.rs

@@ -22,8 +22,8 @@ mod workspace;
 
 use self::{
     cmd::{
-        metadata::MetadataResult, BuildCommand, CallCommand, CheckCommand, InstantiateCommand,
-        TestCommand, UploadCommand,
+        metadata::MetadataResult, BuildCommand, CallCommand, CheckCommand, DecodeCommand,
+        InstantiateCommand, TestCommand, UploadCommand,
     },
     util::DEFAULT_KEY_COL_WIDTH,
     workspace::ManifestPath,
@@ -454,6 +454,9 @@ enum Command {
     /// Call a contract
     #[clap(name = "call")]
     Call(CallCommand),
+    /// Decode a contract input data
+    #[clap(name = "decode")]
+    Decode(DecodeCommand),
 }
 
 fn main() {
@@ -511,6 +514,7 @@ fn exec(cmd: Command) -> Result<()> {
         Command::Upload(upload) => upload.run(),
         Command::Instantiate(instantiate) => instantiate.run(),
         Command::Call(call) => call.run(),
+        Command::Decode(decode) => decode.run(),
     }
 }