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NativeContract.cs
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NativeContract.cs
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// Copyright (C) 2015-2024 The Neo Project.
//
// NativeContract.cs file belongs to the neo project and is free
// software distributed under the MIT software license, see the
// accompanying file LICENSE in the main directory of the
// repository or http://www.opensource.org/licenses/mit-license.php
// for more details.
//
// Redistribution and use in source and binary forms with or without
// modifications are permitted.
using Neo.IO;
using Neo.SmartContract.Manifest;
using Neo.VM;
using System;
using System.Collections.Generic;
using System.Collections.Immutable;
using System.Collections.ObjectModel;
using System.Linq;
using System.Reflection;
using System.Runtime.CompilerServices;
namespace Neo.SmartContract.Native
{
/// <summary>
/// The base class of all native contracts.
/// </summary>
public abstract class NativeContract
{
private class NativeContractsCache
{
public class CacheEntry
{
public Dictionary<int, ContractMethodMetadata> Methods { get; set; }
public byte[] Script { get; set; }
}
internal Dictionary<int, CacheEntry> NativeContracts { get; set; } = new Dictionary<int, CacheEntry>();
public CacheEntry GetAllowedMethods(NativeContract native, ApplicationEngine engine)
{
if (NativeContracts.TryGetValue(native.Id, out var value)) return value;
uint index = engine.PersistingBlock is null ? Ledger.CurrentIndex(engine.Snapshot) : engine.PersistingBlock.Index;
CacheEntry methods = native.GetAllowedMethods(engine.ProtocolSettings.IsHardforkEnabled, index);
NativeContracts[native.Id] = methods;
return methods;
}
}
public delegate bool IsHardforkEnabledDelegate(Hardfork hf, uint index);
private static readonly List<NativeContract> contractsList = new();
private static readonly Dictionary<UInt160, NativeContract> contractsDictionary = new();
private readonly ImmutableHashSet<Hardfork> usedHardforks;
private readonly ReadOnlyCollection<ContractMethodMetadata> methodDescriptors;
private readonly ReadOnlyCollection<ContractEventAttribute> eventsDescriptors;
private static int id_counter = 0;
#region Named Native Contracts
/// <summary>
/// Gets the instance of the <see cref="Native.ContractManagement"/> class.
/// </summary>
public static ContractManagement ContractManagement { get; } = new();
/// <summary>
/// Gets the instance of the <see cref="Native.StdLib"/> class.
/// </summary>
public static StdLib StdLib { get; } = new();
/// <summary>
/// Gets the instance of the <see cref="Native.CryptoLib"/> class.
/// </summary>
public static CryptoLib CryptoLib { get; } = new();
/// <summary>
/// Gets the instance of the <see cref="LedgerContract"/> class.
/// </summary>
public static LedgerContract Ledger { get; } = new();
/// <summary>
/// Gets the instance of the <see cref="NeoToken"/> class.
/// </summary>
public static NeoToken NEO { get; } = new();
/// <summary>
/// Gets the instance of the <see cref="GasToken"/> class.
/// </summary>
public static GasToken GAS { get; } = new();
/// <summary>
/// Gets the instance of the <see cref="PolicyContract"/> class.
/// </summary>
public static PolicyContract Policy { get; } = new();
/// <summary>
/// Gets the instance of the <see cref="Native.RoleManagement"/> class.
/// </summary>
public static RoleManagement RoleManagement { get; } = new();
/// <summary>
/// Gets the instance of the <see cref="OracleContract"/> class.
/// </summary>
public static OracleContract Oracle { get; } = new();
#endregion
/// <summary>
/// Gets all native contracts.
/// </summary>
public static IReadOnlyCollection<NativeContract> Contracts { get; } = contractsList;
/// <summary>
/// The name of the native contract.
/// </summary>
public string Name => GetType().Name;
/// <summary>
/// Since Hardfork has to start having access to the native contract.
/// </summary>
public virtual Hardfork? ActiveIn { get; } = null;
/// <summary>
/// The hash of the native contract.
/// </summary>
public UInt160 Hash { get; }
/// <summary>
/// The id of the native contract.
/// </summary>
public int Id { get; } = --id_counter;
/// <summary>
/// Initializes a new instance of the <see cref="NativeContract"/> class.
/// </summary>
protected NativeContract()
{
Hash = Helper.GetContractHash(UInt160.Zero, 0, Name);
// Reflection to get the methods
List<ContractMethodMetadata> listMethods = new();
foreach (MemberInfo member in GetType().GetMembers(BindingFlags.Instance | BindingFlags.Static | BindingFlags.NonPublic | BindingFlags.Public))
{
ContractMethodAttribute attribute = member.GetCustomAttribute<ContractMethodAttribute>();
if (attribute is null) continue;
listMethods.Add(new ContractMethodMetadata(member, attribute));
}
methodDescriptors = listMethods.OrderBy(p => p.Name, StringComparer.Ordinal).ThenBy(p => p.Parameters.Length).ToList().AsReadOnly();
// Reflection to get the events
eventsDescriptors =
GetType().GetConstructor(BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Public, null, Array.Empty<Type>(), null)?.
GetCustomAttributes<ContractEventAttribute>().
// Take into account not only the contract constructor, but also the base type constructor for proper FungibleToken events handling.
Concat(GetType().BaseType?.GetConstructor(BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Public, null, Array.Empty<Type>(), null)?.
GetCustomAttributes<ContractEventAttribute>()).
OrderBy(p => p.Order).ToList().AsReadOnly();
// Calculate the initializations forks
usedHardforks =
methodDescriptors.Select(u => u.ActiveIn)
.Concat(eventsDescriptors.Select(u => u.ActiveIn))
.Concat(new Hardfork?[] { ActiveIn })
.Where(u => u is not null)
.OrderBy(u => (byte)u)
.Cast<Hardfork>().ToImmutableHashSet();
contractsList.Add(this);
contractsDictionary.Add(Hash, this);
}
/// <summary>
/// The allowed methods and his offsets.
/// </summary>
/// <param name="hfChecker">Hardfork checker</param>
/// <param name="index">Block index</param>
/// <returns>The <see cref="NativeContractsCache"/>.</returns>
private NativeContractsCache.CacheEntry GetAllowedMethods(IsHardforkEnabledDelegate hfChecker, uint index)
{
Dictionary<int, ContractMethodMetadata> methods = new();
// Reflection to get the ContractMethods
byte[] script;
using (ScriptBuilder sb = new())
{
foreach (ContractMethodMetadata method in methodDescriptors.Where(u
=>
// no hardfork is involved
u.ActiveIn is null && u.DeprecatedIn is null ||
// deprecated method hardfork is involved
u.DeprecatedIn is not null && hfChecker(u.DeprecatedIn.Value, index) == false ||
// active method hardfork is involved
u.ActiveIn is not null && hfChecker(u.ActiveIn.Value, index))
)
{
method.Descriptor.Offset = sb.Length;
sb.EmitPush(0); //version
methods.Add(sb.Length, method);
sb.EmitSysCall(ApplicationEngine.System_Contract_CallNative);
sb.Emit(OpCode.RET);
}
script = sb.ToArray();
}
return new NativeContractsCache.CacheEntry() { Methods = methods, Script = script };
}
/// <summary>
/// The <see cref="ContractState"/> of the native contract.
/// </summary>
/// <param name="settings">The <see cref="ProtocolSettings"/> where the HardForks are configured.</param>
/// <param name="index">Block index</param>
/// <returns>The <see cref="ContractState"/>.</returns>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public ContractState GetContractState(ProtocolSettings settings, uint index) => GetContractState(settings.IsHardforkEnabled, index);
/// <summary>
/// The <see cref="ContractState"/> of the native contract.
/// </summary>
/// <param name="hfChecker">Hardfork checker</param>
/// <param name="index">Block index</param>
/// <returns>The <see cref="ContractState"/>.</returns>
public ContractState GetContractState(IsHardforkEnabledDelegate hfChecker, uint index)
{
// Get allowed methods and nef script
var allowedMethods = GetAllowedMethods(hfChecker, index);
// Compose nef file
var nef = new NefFile()
{
Compiler = "neo-core-v3.0",
Source = string.Empty,
Tokens = Array.Empty<MethodToken>(),
Script = allowedMethods.Script
};
nef.CheckSum = NefFile.ComputeChecksum(nef);
// Compose manifest
var manifest = new ContractManifest()
{
Name = Name,
Groups = Array.Empty<ContractGroup>(),
SupportedStandards = Array.Empty<string>(),
Abi = new ContractAbi()
{
Events = eventsDescriptors
.Where(u => u.ActiveIn is null || hfChecker(u.ActiveIn.Value, index))
.Select(p => p.Descriptor).ToArray(),
Methods = allowedMethods.Methods.Values
.Select(p => p.Descriptor).ToArray()
},
Permissions = new[] { ContractPermission.DefaultPermission },
Trusts = WildcardContainer<ContractPermissionDescriptor>.Create(),
Extra = null
};
OnManifestCompose(manifest);
// Return ContractState
return new ContractState
{
Id = Id,
Nef = nef,
Hash = Hash,
Manifest = manifest
};
}
protected virtual void OnManifestCompose(ContractManifest manifest) { }
/// <summary>
/// It is the initialize block
/// </summary>
/// <param name="settings">The <see cref="ProtocolSettings"/> where the HardForks are configured.</param>
/// <param name="index">Block index</param>
/// <param name="hardforks">Active hardforks</param>
/// <returns>True if the native contract must be initialized</returns>
internal bool IsInitializeBlock(ProtocolSettings settings, uint index, out Hardfork[] hardforks)
{
var hfs = new List<Hardfork>();
// If is in the hardfork height, add them to return array
foreach (var hf in usedHardforks)
{
if (!settings.Hardforks.TryGetValue(hf, out var activeIn))
{
// If is not set in the configuration is treated as enabled from the genesis
activeIn = 0;
}
if (activeIn == index)
{
hfs.Add(hf);
}
}
// Return all initialize hardforks
if (hfs.Count > 0)
{
hardforks = hfs.ToArray();
return true;
}
// If is not configured, the Genesis is an initialization block.
if (index == 0 && ActiveIn is null)
{
hardforks = hfs.ToArray();
return true;
}
// Initialized not required
hardforks = null;
return false;
}
/// <summary>
/// Is the native contract active
/// </summary>
/// <param name="settings">The <see cref="ProtocolSettings"/> where the HardForks are configured.</param>
/// <param name="index">Block index</param>
/// <returns>True if the native contract is active</returns>
internal bool IsActive(ProtocolSettings settings, uint index)
{
if (ActiveIn is null) return true;
if (!settings.Hardforks.TryGetValue(ActiveIn.Value, out var activeIn))
{
// If is not set in the configuration is treated as enabled from the genesis
activeIn = 0;
}
return activeIn <= index;
}
/// <summary>
/// Checks whether the committee has witnessed the current transaction.
/// </summary>
/// <param name="engine">The <see cref="ApplicationEngine"/> that is executing the contract.</param>
/// <returns><see langword="true"/> if the committee has witnessed the current transaction; otherwise, <see langword="false"/>.</returns>
protected static bool CheckCommittee(ApplicationEngine engine)
{
UInt160 committeeMultiSigAddr = NEO.GetCommitteeAddress(engine.Snapshot);
return engine.CheckWitnessInternal(committeeMultiSigAddr);
}
private protected KeyBuilder CreateStorageKey(byte prefix)
{
return new KeyBuilder(Id, prefix);
}
/// <summary>
/// Gets the native contract with the specified hash.
/// </summary>
/// <param name="hash">The hash of the native contract.</param>
/// <returns>The native contract with the specified hash.</returns>
public static NativeContract GetContract(UInt160 hash)
{
contractsDictionary.TryGetValue(hash, out var contract);
return contract;
}
internal async void Invoke(ApplicationEngine engine, byte version)
{
try
{
if (version != 0)
throw new InvalidOperationException($"The native contract of version {version} is not active.");
// Get native contracts invocation cache
NativeContractsCache nativeContracts = engine.GetState(() => new NativeContractsCache());
NativeContractsCache.CacheEntry currentAllowedMethods = nativeContracts.GetAllowedMethods(this, engine);
// Check if the method is allowed
ExecutionContext context = engine.CurrentContext;
ContractMethodMetadata method = currentAllowedMethods.Methods[context.InstructionPointer];
if (method.ActiveIn is not null && !engine.IsHardforkEnabled(method.ActiveIn.Value))
throw new InvalidOperationException($"Cannot call this method before hardfork {method.ActiveIn}.");
if (method.DeprecatedIn is not null && engine.IsHardforkEnabled(method.DeprecatedIn.Value))
throw new InvalidOperationException($"Cannot call this method after hardfork {method.DeprecatedIn}.");
ExecutionContextState state = context.GetState<ExecutionContextState>();
if (!state.CallFlags.HasFlag(method.RequiredCallFlags))
throw new InvalidOperationException($"Cannot call this method with the flag {state.CallFlags}.");
engine.AddGas(method.CpuFee * engine.ExecFeeFactor + method.StorageFee * engine.StoragePrice);
List<object> parameters = new();
if (method.NeedApplicationEngine) parameters.Add(engine);
if (method.NeedSnapshot) parameters.Add(engine.Snapshot);
for (int i = 0; i < method.Parameters.Length; i++)
parameters.Add(engine.Convert(context.EvaluationStack.Peek(i), method.Parameters[i]));
object returnValue = method.Handler.Invoke(this, parameters.ToArray());
if (returnValue is ContractTask task)
{
await task;
returnValue = task.GetResult();
}
for (int i = 0; i < method.Parameters.Length; i++)
{
context.EvaluationStack.Pop();
}
if (method.Handler.ReturnType != typeof(void) && method.Handler.ReturnType != typeof(ContractTask))
{
context.EvaluationStack.Push(engine.Convert(returnValue));
}
}
catch (Exception ex)
{
engine.Throw(ex);
}
}
/// <summary>
/// Determine whether the specified contract is a native contract.
/// </summary>
/// <param name="hash">The hash of the contract.</param>
/// <returns><see langword="true"/> if the contract is native; otherwise, <see langword="false"/>.</returns>
public static bool IsNative(UInt160 hash)
{
return contractsDictionary.ContainsKey(hash);
}
internal virtual ContractTask InitializeAsync(ApplicationEngine engine, Hardfork? hardFork)
{
return ContractTask.CompletedTask;
}
internal virtual ContractTask OnPersistAsync(ApplicationEngine engine)
{
return ContractTask.CompletedTask;
}
internal virtual ContractTask PostPersistAsync(ApplicationEngine engine)
{
return ContractTask.CompletedTask;
}
}
}