From a3c60a1951e1f18cf9218f594b669101cf7908b4 Mon Sep 17 00:00:00 2001
From: garrettmills <shout@garrettmills.dev>
Date: Sat, 10 Apr 2021 09:34:04 -0500
Subject: [PATCH] Fix logic for validating blockchain and expose debugging
 endpoint

---
 .../controllers/api/Blockchain.controller.ts  |  9 ++-
 src/app/http/routes/app.routes.ts             |  3 +
 src/app/units/Blockchain.ts                   | 74 ++++++++++++++-----
 3 files changed, 68 insertions(+), 18 deletions(-)

diff --git a/src/app/http/controllers/api/Blockchain.controller.ts b/src/app/http/controllers/api/Blockchain.controller.ts
index 5453839..065f91c 100644
--- a/src/app/http/controllers/api/Blockchain.controller.ts
+++ b/src/app/http/controllers/api/Blockchain.controller.ts
@@ -2,7 +2,7 @@ import {Controller} from "@extollo/lib"
 import {Injectable, Inject} from "@extollo/di"
 import {TransactionResource, TransactionResourceItem} from "../../../rtdb/TransactionResource"
 import {many, one} from "@extollo/util"
-import {Blockchain as BlockchainService} from "../../../units/Blockchain"
+import {Block, Blockchain as BlockchainService} from "../../../units/Blockchain"
 import {ExposureResource, ExposureResourceItem} from "../../../rtdb/ExposureResource";
 
 /**
@@ -26,6 +26,13 @@ export class Blockchain extends Controller {
         }))
     }
 
+    public async validate() {
+        const blocks = (await this.blockchain.read()).map(x => new Block(x))
+        return {
+            is_valid: await this.blockchain.validate(blocks)
+        }
+    }
+
     /**
      * Post a new transaction to the blockchain. This is only intended for testing.
      */
diff --git a/src/app/http/routes/app.routes.ts b/src/app/http/routes/app.routes.ts
index a6978d8..0226b22 100644
--- a/src/app/http/routes/app.routes.ts
+++ b/src/app/http/routes/app.routes.ts
@@ -9,5 +9,8 @@ Route.group('/api/v1', () => {
         .pre('DebugOnly')
         .pre('api:ValidateExposureTransaction')
 
+    Route.post('/validate', 'api:Blockchain.validate')
+        .pre('DebugOnly')
+
     Route.get('/chain', 'api:Blockchain.readBlockchain')
 })
diff --git a/src/app/units/Blockchain.ts b/src/app/units/Blockchain.ts
index 4ec1980..8c70e16 100644
--- a/src/app/units/Blockchain.ts
+++ b/src/app/units/Blockchain.ts
@@ -44,15 +44,17 @@ export class Block implements BlockResourceItem {
         }
         const proof = this.proof
         const publicKey = this.config.get("app.gpg.key.public")
-        const message = openpgp.Message.fromText(proof)
 
-        // Verify the signature
-        const verified = await (await openpgp.verify({
-            message,
-            publicKeys: publicKey
-        })).signatures[0].verified
+        const result = await openpgp.verify({
+            publicKeys: await openpgp.readKey({
+                armoredKey: publicKey,
+            }),
+            message: await openpgp.readMessage({
+                armoredMessage: proof,
+            }),
+        })
 
-        return !!verified
+        return !!(await result.signatures?.[0]?.verified)
     }
 
     /** Generate the hash for this block. */
@@ -80,7 +82,7 @@ export class Block implements BlockResourceItem {
     toString() {
         return [
             this.uuid,
-            JSON.stringify(this.transactions),
+            JSON.stringify(this.transactions || [], undefined, 0),
             this.lastBlockHash,
             this.lastBlockUUID,
         ].join('%')
@@ -145,7 +147,43 @@ export class Blockchain extends Unit {
      */
     public async validate(chain: Block[]) {
         const blocks = collect<Block>(chain)
-        return (await blocks.promiseMap((block: Block) => block.isGenesis())).every(Boolean)
+        return (
+            await blocks.promiseMap(async (block, idx) => {
+                if ( await block.isGenesis() ) {
+                    return true
+                }
+
+                const previous: Block | undefined = blocks.at(idx - 1)
+                if ( !previous ) {
+                    this.logging.debug(`Chain is invalid: block ${idx} is missing previous ${idx - 1}.`)
+                    return false;
+                }
+
+                if ( !(await this.validateProofOfWork(block, previous)) ) {
+                    this.logging.debug(`Chain is invalid: block ${idx} failed proof of work validation`)
+                    return false;
+                }
+
+
+
+                const pass = (
+                    block.lastBlockUUID === previous.uuid
+                    && block.lastBlockHash === previous.hash()
+                )
+
+                if ( !pass ) {
+                    this.logging.debug(`Chain is invalid: block ${idx} does not match previous.`)
+                    this.logging.debug({
+                        lastBlockUUID: block.lastBlockUUID,
+                        computedLastUUID: previous.uuid,
+                        lastBlockHash: block.lastBlockHash,
+                        computedLastHash: previous.hash(),
+                    })
+                }
+
+                return pass
+            })
+        ).every(Boolean)
     }
 
     public async refresh() {
@@ -276,7 +314,7 @@ export class Blockchain extends Unit {
             privateKeys: await openpgp.readKey({
                 armoredKey: privateKey,
             })
-        })).toString()
+        }))
     }
 
     /**
@@ -288,14 +326,16 @@ export class Blockchain extends Unit {
     protected async validateProofOfWork(currentBlock: Block, lastBlock: Block): Promise<boolean> {
         const proof = lastBlock.proof
         const publicKey = this.config.get("app.gpg.key.public")
-        const message = openpgp.Message.fromText(proof)
 
-        // Verify the signature
-        const verified = await (await openpgp.verify({
-            message,
-            publicKeys: publicKey
-        })).signatures[0].verified
+        const result = await openpgp.verify({
+            publicKeys: await openpgp.readKey({
+                armoredKey: publicKey,
+            }),
+            message: await openpgp.readMessage({
+                armoredMessage: proof,
+            }),
+        })
 
-        return !!verified
+        return !!(await result.signatures?.[0]?.verified)
     }
 }