Do not merge: We need to make an approach to verification

Lets talk about verification.md

@@ -0,0 +1,101 @@
+**This description is still approximate and not accurate, we need to define an approach and agree on checks.**
+
+## Draft TransactionVerifier
+
+I suggest adding a structure that will contain: 
+
+```rust
+pub struct TransactionVerifier<'a, T: frame_system::Config> {
+    // Pointer to a tx that we have to check 
+    tx: &'a TransactionFor<T>,
+    // All inputs, to avoid repeated search in the loop 
+    all_inputs_map: BTreeMap<TokenId, TransactionOutputFor<T>>,
+    // All outputs, to avoid repeated search in the loop 
+    all_outputs_map: BTreeMap<TokenId, TransactionOutputFor<T>>,
+    // Using TokenId, you can get the entire amount of this token in all inputs 
+    total_value_of_input_tokens: BTreeMap<TokenId, TransactionOutputFor<T>>,
+    // Using TokenId, you can get the entire amount of this token in all outputs 
+    total_value_of_output_tokens: BTreeMap<TokenId, TransactionOutputFor<T>>,
+    // A set of transaction verification functions, this approach will allow you to remove unnecessary cycles, which will speed up the function 
+    set_of_checks: Vec<&'a mut FnMut(...)>,
+    // ...
+    // I may add a priority field to the set of checks. I'm still thinking here. 
+}
+```
+
+This struct we will use this way in the pallet utxo:
+
+```rust
+    pub fn validate_transaction<T: Config>(
+        tx: &TransactionFor<T>,
+    ) -> Result<ValidTransaction, &'static str> {
+        TransactionVerifier::<'_, T>::new(tx)
+            .checking_inputs()
+            .checking_outputs()
+            .checking_utxos_exists()
+            .checking_signatures()
+            .checking_tokens_transferring()
+            .checking_tokens_issued()
+            .checking_nft_mint()
+            .checking_assets_burn()
+            .calculating_reward()
+            .collect_result()?
+    }
+
+```
+
+When creating a new instance of this structure, we must initialize the fields. 
+
+Each subsequent check adds a new instance of the function to `set_of_checks`, which will be called in` collect_result`. 
+
+At the moment we can split the verification function for these parts: 
+
+* `checking_inputs`
+  * Checks that inputs exist in a transaction 
+  * Checking that the number of inputs is not more than the maximum allowed number, now in the code I see that it is `u32::MAX` 
+  * Ensure each input is used only a single time
+
+* `checking_outputs`
+  * Checks that outputs exist in a transaction 
+  * Checking that the number of outputs is not more than the maximum allowed number, now in the code I see that it is `u32::MAX` 
+  * Ensure each output is unique
+  * Output value must be nonzero
+  * An output can't exist already in the UtxoStore
+
+* `checking_utxos_exists` 
+  * Resolve the transaction inputs by looking up UTXOs being spent by them.
+
+* `checking_signatures`
+  * if all spent UTXOs are available, check the math and signatures
+
+* `checking_tokens_transferring`
+  * We have to check that the total sum of input tokens is less or equal to output tokens. (Or just equal?) 
+  * All inputs with such data code must be correctly mapped to outputs 
+  * If NFT is sent we must not burn or lose data 
+
+* `checking_tokens_issued`
+  * We must check the correctness of the issued tokens
+  * We have to check the length of `metadata_uri` and` ticker` 
+  * We must check the correctness of `value` and `decimal` 
+
+* `checking_nft_mint`
+  * We have to check the uniqueness of digital data, only one NFT can refer to one object 
+  * We have to check the length of `metadata_uri`
+
+* `checking_assets_burn`
+  * Is there burn more than possible?
+  * Is there tocken_id exist for the burn?
+
+* `calculating_reward`
+  * Just collecting MLT for a transaction reward.
+
+* `collect_result`
+  * Call all of these functions in one loop.
+
+## Questions
+* Do we need other checks? 
+* What is we need for checking Bitcoin Script? 
+* What is we need for checking contracts?
+* If we can check an output address here, and add a possibility to find in the UtxoStore by any address format, then we can remove `fn pick_utxo` and `fn send_to_address`. Isn't that?
+
+I'm glad to see any suggestions or critics.

node/Cargo.toml

@@ -24,7 +24,6 @@ structopt = '0.3.8'
 node-template-runtime = {version = '3.0.0', path = '../runtime'}
 pallet-utxo-rpc = { path = "../pallets/utxo/rpc" }
 pallet-utxo-rpc-runtime-api = { path = "../pallets/utxo/rpc/runtime-api" }
-pallet-utxo-tokens = { path = "../pallets/utxo/tokens" }
 log = "0.4.8"
 ureq = "2.2.0"
 

node/src/chain_spec.rs

@@ -164,7 +164,7 @@ fn testnet_genesis(
         .map(|x| {
             // may need to create a const variable to represent 1_000 and 100_000_000
             pallet_utxo::TransactionOutput::new_pubkey(
-                1_000 * 100_000_000 * 400_000_000 as pallet_utxo::Value,
+                1_000 * 100_000_000 * 400_000_000 as pallet_utxo::tokens::Value,
                 H256::from_slice(x.as_slice()),
             )
         })

pallets/utxo/Cargo.toml

@@ -21,7 +21,6 @@ std = [
 hex-literal = "0.2.1"
 log = "0.4.8"
 serde = '1.0.119'
-pallet-utxo-tokens = { path = "./tokens" }
 variant_count = '1.1'
 
 [dependencies.bech32]
@@ -36,7 +35,7 @@ version = '0.1.0'
 
 [dependencies.codec]
 default-features = false
-features = ['derive']
+features = ["derive", "chain-error"]
 package = 'parity-scale-codec'
 version = '2.0.0'
 

pallets/utxo/rpc/Cargo.toml

@@ -6,7 +6,6 @@ edition = "2018"
 
 [dependencies]
 pallet-utxo-rpc-runtime-api = { path = "./runtime-api" }
-pallet-utxo-tokens = {path = "../tokens"}
 jsonrpc-core = "18.0.0"
 jsonrpc-core-client = "18.0.0"
 jsonrpc-derive = "18.0.0"
@@ -44,3 +43,9 @@ default-features = false
 git = 'https://github.com/paritytech/substrate.git'
 version = '4.0.0-dev'
 branch = "master"
+
+[dependencies.sp-core]
+default-features = false
+git = 'https://github.com/paritytech/substrate.git'
+version = '4.0.0-dev'
+branch = "master"

pallets/utxo/rpc/runtime-api/Cargo.toml

@@ -4,9 +4,6 @@ version = "0.1.0"
 authors = ["RBB Lab"]
 edition = "2018"
 
-[dependencies]
-pallet-utxo-tokens = { path = "../../tokens" }
-
 [dependencies.serde]
 version = "1.0.104"
 optional = true
@@ -36,6 +33,12 @@ git = 'https://github.com/paritytech/substrate.git'
 version = '4.0.0-dev'
 branch = "master"
 
+[dependencies.sp-core]
+default-features = false
+git = 'https://github.com/paritytech/substrate.git'
+version = '4.0.0-dev'
+branch = "master"
+
 [dev-dependencies]
 serde_json = "1.0.48"
 

pallets/utxo/rpc/runtime-api/src/lib.rs

@@ -16,15 +16,8 @@
 // Author(s): A. Altonen, Anton Sinitsyn
 #![cfg_attr(not(feature = "std"), no_std)]
 
-use frame_support::inherent::Vec;
-
 sp_api::decl_runtime_apis! {
     pub trait UtxoApi {
         fn send() -> u32;
-        // What means Vec<(u64, Vec<u8>)> ?
-        // At the moment we have some problems with use serde in RPC, we can serialize and deserialize
-        // only simple types. This approach allow us to return Vec<(TokenId, TokenName)> instead of
-        // pallet_utxo_tokens::TokenListData
-        fn tokens_list() -> Vec<(u64, Vec<u8>)>;
     }
 }

pallets/utxo/rpc/src/lib.rs

@@ -27,10 +27,6 @@ use std::sync::Arc;
 pub trait UtxoApi<BlockHash> {
     #[rpc(name = "utxo_send")]
     fn send(&self, at: Option<BlockHash>) -> Result<u32>;
-
-    // What means Vec<(u64, Vec<u8>)> ? Have a look at utxo/rpc/runtime-api/src/lib.rs
-    #[rpc(name = "tokens_list")]
-    fn tokens_list(&self, at: Option<BlockHash>) -> Result<Vec<(u64, Vec<u8>)>>;
 }
 
 /// A struct that implements the [`UtxoApi`].
@@ -79,18 +75,4 @@ where
             data: Some(format!("{:?}", e).into()),
         })
     }
-
-    fn tokens_list(&self, at: Option<<Block as BlockT>::Hash>) -> Result<Vec<(u64, Vec<u8>)>> {
-        let api = self.client.runtime_api();
-        let at = BlockId::hash(at.unwrap_or_else(||
-            // If the block hash is not supplied assume the best block.
-            self.client.info().best_hash));
-
-        let runtime_api_result = api.tokens_list(&at);
-        runtime_api_result.map_err(|e| RpcError {
-            code: ErrorCode::ServerError(Error::StorageError as i64),
-            message: "Something wrong".into(),
-            data: Some(format!("{:?}", e).into()),
-        })
-    }
 }