想学习区块链？那就用 Python 构建一个 | Linux 中国(4)

               return False

           # Check that the Proof of Work is correct

           if not self.valid_proof(last_block["proof"], block["proof"]):

               return False

           last_block = block

           current_index += 1

       return True

   def resolve_conflicts(self):

       """

       This is our Consensus Algorithm, it resolves conflicts

       by replacing our chain with the longest one in the network.

       :return: <bool> True if our chain was replaced, False if not

       """

       neighbours = self.nodes

       new_chain = None

       # We"re only looking for chains longer than ours

       max_length = len(self.chain)

       # Grab and verify the chains from all the nodes in our network

       for node in neighbours:

           response = requests.get(f"http://{node}/chain")

           if response.status_code == 200:

               length = response.json()["length"]

               chain = response.json()["chain"]

               # Check if the length is longer and the chain is valid

               if length > max_length and self.valid_chain(chain):

                   max_length = length

                   new_chain = chain

       # Replace our chain if we discovered a new, valid chain longer than ours

       if new_chain:

           self.chain = new_chain

           return True

       return False

@app.route("/nodes/register", methods=["POST"])

def register_nodes():

   values = request.get_json()

   nodes = values.get("nodes")

   if nodes is None:

       return "Error: Please supply a valid list of nodes", 400

   for node in nodes:

       blockchain.register_node(node)

   response = {

       "message": "New nodes have been added",

       "total_nodes": list(blockchain.nodes),

   }

   return jsonify(response), 201

@app.route("/nodes/resolve", methods=["GET"])

def consensus():

   replaced = blockchain.resolve_conflicts()

   if replaced:

       response = {

           "message": "Our chain was replaced",

           "new_chain": blockchain.chain

       }

   else:

       response = {

           "message": "Our chain is authoritative",

           "chain": blockchain.chain

       }

   return jsonify(response), 200