wip: blockchain: local validation

Closes #146 (closed)

lib/modules/blockchain/blockchain/src/dubp/check/global.rs

+//  Copyright (C) 2017-2019  The AXIOM TEAM Association.
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as
+// published by the Free Software Foundation, either version 3 of the
+// License, or (at your option) any later version.
+//
+// This program 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 Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+//! Sub-module checking if a block complies with all the rules of the (DUBP DUniter Blockchain Protocol).
+
+use crate::dubp::BlockError;
+use dubp_block_doc::block::{BlockDocument, BlockDocumentTrait};
+use dubp_common_doc::traits::Document;
+use dubp_common_doc::BlockNumber;
+use dup_crypto::keys::PubKey;
+use durs_bc_db_reader::DbReadable;
+use durs_bc_db_reader::DbReader;
+use durs_bc_db_writer::BinFreeStructDb;
+use durs_wot::*;
+use std::collections::HashMap;
+
+#[derive(Debug, Copy, Clone)]
+pub enum GlobalVerifyBlockError {
+    NoPreviousBlock,
+    VersionDecrease,
+}
+
+pub fn verify_global_validity_block<DB, R, W>(
+    block: &BlockDocument,
+    db: &DB,
+    r: &R,
+    _wot_index: &HashMap<PubKey, WotId>,
+    _wot_db: &BinFreeStructDb<W>,
+) -> Result<(), BlockError>
+where
+    DB: DbReadable,
+    R: DbReader,
+    W: WebOfTrust,
+{
+    // Rules that do not concern genesis block
+    if block.number().0 > 0 {
+        // Get previous block
+        let previous_block_opt = durs_bc_db_reader::blocks::get_block_in_local_blockchain(
+            db,
+            r,
+            BlockNumber(block.number().0 - 1),
+        )?;
+
+        // Previous block must exist
+        if previous_block_opt.is_none() {
+            return Err(BlockError::InvalidBlock(super::InvalidBlockError::Global(
+                GlobalVerifyBlockError::NoPreviousBlock,
+            )));
+        }
+        let previous_block = previous_block_opt.expect("safe unwrap");
+
+        // Block version must not decrease
+        if previous_block.version() > block.version() {
+            return Err(BlockError::InvalidBlock(super::InvalidBlockError::Global(
+                GlobalVerifyBlockError::VersionDecrease,
+            )));
+        }
+    }
+
+    Ok(())
+}