tari_engine 0.28.2

//  Copyright 2022. The Tari Project
//
//  Redistribution and use in source and binary forms, with or without modification, are permitted provided that the
//  following conditions are met:
//
//  1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following
//  disclaimer.
//
//  2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the
//  following disclaimer in the documentation and/or other materials provided with the distribution.
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//  3. Neither the name of the copyright holder nor the names of its contributors may be used to endorse or promote
//  products derived from this software without specific prior written permission.
//
//  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
//  INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
//  DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
//  SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
//  SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
//  WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
//  USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

use std::{fmt, fmt::Formatter, sync::Arc};

use tari_engine_types::limits;
use tari_template_abi::{ABI_TEMPLATE_DEF_GLOBAL_NAME, FunctionDef, TemplateDef, Type};
use wasmer::{
    AsStoreMut,
    Engine,
    ExportError,
    Function,
    Instance,
    Pages,
    Store,
    TypedFunction,
    WasmPtr,
    imports,
    sys::{BaseTunables, CompilerConfig, Cranelift, CraneliftOptLevel, EngineBuilder, Target},
};

use crate::{
    template::{LoadedTemplate, TemplateLoaderError, TemplateModuleLoader},
    wasm::{
        WasmExecutionError,
        WasmProcess,
        WasmValidationError,
        environment::WasmEnv,
        limiting_tunable::LimitingTunables,
        metering,
    },
};

pub type MainFunction = TypedFunction<(WasmPtr<u8>, u32), WasmPtr<u8>>;
#[derive(Debug, Clone)]
pub struct WasmModule {
    code: Box<[u8]>,
}

impl WasmModule {
    pub fn from_code(code: impl Into<Box<[u8]>>) -> Self {
        Self { code: code.into() }
    }

    pub fn load_template_from_code(code: &[u8]) -> Result<LoadedTemplate, TemplateLoaderError> {
        let engine = Self::create_engine();
        let module = wasmer::Module::new(&engine, code)?;
        let mut store = Store::new(engine);

        let imports = imports! {
            "env" => {
                "tari_engine" => Function::new_typed(&mut store, |_op: i32, _arg_ptr: i32, _arg_len: i32| 0i32),
                "tari_debug" => Function::new_typed(&mut store, |_arg_ptr: i32, _arg_len: i32| {  }),
                "on_panic" => Function::new_typed(&mut store, |_msg_ptr: i32, _msg_len: i32, _line: i32, _col: i32| {  }),
            }
        };
        let instance = Instance::new(&mut store, &module, &imports)?;
        let mut env = WasmEnv::new(());
        let memory = instance.exports.get_memory("memory")?.clone();
        env.set_memory(memory);

        let template = env.load_template_def(&mut store, &instance)?;
        let main_fn = format!("{}_main", template.template_name());

        WasmProcess::validate_template_abi_version(&template)?;
        validate_instance(&mut store, &instance, &main_fn)?;
        validate_functions(&template)?;

        let engine = store.engine().clone();

        Ok(LoadedWasmTemplate::new(template, module, engine, code.len()).into())
    }

    pub fn code(&self) -> &[u8] {
        &self.code
    }

    pub fn into_code(self) -> Box<[u8]> {
        self.code
    }

    fn create_engine() -> Engine {
        const MEMORY_PAGE_LIMIT: Pages = Pages(limits::WASM_LIMITS.max_memory_pages as u32);
        let base = BaseTunables::for_target(&Target::default());
        let tunables = LimitingTunables::new(base, MEMORY_PAGE_LIMIT);
        let mut compiler = Cranelift::new();
        compiler
            .opt_level(CraneliftOptLevel::SpeedAndSize)
            .canonicalize_nans(true);
        // TODO: Configure metering limit
        compiler.push_middleware(Arc::new(metering::middleware(100_000_000)));

        let mut features = wasmer::sys::Features::default();
        features
            // Explicitly disable threads and multi value, the remaining defaults are repeated here for clarity
            .threads(false)
            .bulk_memory(true)
            .multi_value(false)
            .reference_types(true)
            .simd(true)
            .tail_call(false)
            .memory64(false)
            .multi_memory(false)
            .exceptions(false)
            .module_linking(false);

        let mut engine = EngineBuilder::new(compiler).set_features(Some(features)).engine();
        engine.set_tunables(tunables);
        Engine::from(engine)
    }
}

impl TemplateModuleLoader for WasmModule {
    fn load_template(&self) -> Result<LoadedTemplate, TemplateLoaderError> {
        Self::load_template_from_code(&self.code)
    }
}

#[derive(Clone)]
pub struct LoadedWasmTemplate {
    template_def: Arc<TemplateDef>,
    module: wasmer::Module,
    engine: Engine,
    code_size: usize,
}

impl LoadedWasmTemplate {
    pub fn new(template_def: TemplateDef, module: wasmer::Module, engine: Engine, code_size: usize) -> Self {
        Self {
            template_def: Arc::new(template_def),
            module,
            engine,
            code_size,
        }
    }

    pub fn wasm_module(&self) -> &wasmer::Module {
        &self.module
    }

    pub fn engine(&self) -> &Engine {
        &self.engine
    }

    pub fn create_store(&self) -> Store {
        Store::new(self.engine.clone())
    }

    pub fn template_name(&self) -> &str {
        self.template_def.template_name()
    }

    pub fn template_def(&self) -> &TemplateDef {
        &self.template_def
    }

    pub fn into_template_def(self) -> TemplateDef {
        Arc::try_unwrap(self.template_def).unwrap_or_else(|arc| (*arc).clone())
    }

    pub fn find_func_by_name(&self, function_name: &str) -> Option<&FunctionDef> {
        self.template_def.functions().iter().find(|f| f.name == *function_name)
    }

    pub fn code_size(&self) -> usize {
        self.code_size
    }
}

impl fmt::Debug for LoadedWasmTemplate {
    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
        f.debug_struct("LoadedWasmTemplate")
            .field("template_name", &self.template_name())
            .field("code_size", &self.code_size())
            .field("main", &"<main func>")
            .field("module", &self.module)
            .finish()
    }
}

fn validate_instance<S: AsStoreMut>(
    store: &mut S,
    instance: &Instance,
    main_fn: &str,
) -> Result<(), WasmExecutionError> {
    fn is_func_permitted(name: &str, main_fn: &str) -> bool {
        name == main_fn || name == "tari_alloc" || name == "tari_free"
    }

    instance.exports.get_memory("memory")?;

    // Enforce that only permitted functions are allowed
    let unexpected_abi_func = instance
        .exports
        .iter()
        .functions()
        .find(|(name, _)| !is_func_permitted(name, main_fn));

    if let Some((name, _)) = unexpected_abi_func {
        return Err(WasmExecutionError::UnexpectedAbiFunction { name: name.to_string() });
    }

    instance
        .exports
        .get_global(ABI_TEMPLATE_DEF_GLOBAL_NAME)?
        .get(store)
        .i32()
        .ok_or(WasmExecutionError::ExportError(ExportError::IncompatibleType))?;

    // Check that the main function exists and it's signature is correct
    let _main: MainFunction = instance.exports.get_typed_function(store, main_fn)?;

    Ok(())
}

fn validate_functions(template_def: &TemplateDef) -> Result<(), WasmExecutionError> {
    match template_def {
        TemplateDef::V1(def) => {
            let function_count = def.functions.len();
            if function_count > limits::WASM_LIMITS.max_functions {
                return Err(WasmValidationError::TooManyFunctions {
                    max_functions: limits::WASM_LIMITS.max_functions,
                }
                .into());
            }
            for func in &def.functions {
                if func.name.len() > limits::WASM_LIMITS.max_function_name_length {
                    return Err(WasmValidationError::FunctionNameTooLong {
                        name: func.name.clone(),
                        max_length: limits::WASM_LIMITS.max_function_name_length,
                    }
                    .into());
                }

                if func.arguments.len() > limits::WASM_LIMITS.max_function_arguments {
                    return Err(WasmValidationError::FunctionTooManyArguments {
                        name: func.name.clone(),
                        max_args: limits::WASM_LIMITS.max_function_arguments,
                        num_args: func.arguments.len(),
                    }
                    .into());
                }
                for arg in &func.arguments {
                    if arg.name.len() > limits::WASM_LIMITS.max_function_name_length {
                        return Err(WasmValidationError::FunctionNameTooLong {
                            name: arg.name.clone(),
                            max_length: limits::WASM_LIMITS.max_function_name_length,
                        }
                        .into());
                    }
                    match &arg.arg_type {
                        Type::Tuple(tuple) => {
                            if tuple.len() > limits::WASM_LIMITS.max_function_arguments {
                                return Err(WasmValidationError::FunctionTooManyTupleReturn {
                                    name: func.name.clone(),
                                    max_tuple_size: limits::WASM_LIMITS.max_function_arguments,
                                    tuple_size: tuple.len(),
                                }
                                .into());
                            }
                        },
                        Type::Other { name } => {
                            if name.len() > limits::WASM_LIMITS.max_function_name_length {
                                return Err(WasmValidationError::FunctionNameTooLong {
                                    name: name.clone(),
                                    max_length: limits::WASM_LIMITS.max_function_name_length,
                                }
                                .into());
                            }
                        },
                        _ => {},
                    }
                }
                if func.is_migration {
                    // Note that we are checking the TemplateDef, not the actual return type of the function in Wasm.
                    match &func.output {
                        Type::Other { name } => {
                            if name != "Self" &&
                                name != template_def.template_name() &&
                                name != "Component<Self>" &&
                                *name != format!("Component<{}>", template_def.template_name())
                            {
                                return Err(WasmValidationError::InvalidMigrationReturnType {
                                    function_name: func.name.clone(),
                                    return_type: func.output.clone(),
                                }
                                .into());
                            }
                        },
                        _ => {
                            return Err(WasmValidationError::InvalidMigrationReturnType {
                                function_name: func.name.clone(),
                                return_type: func.output.clone(),
                            }
                            .into());
                        },
                    }
                }
            }
        },
    }
    Ok(())
}