Add ping endpoint for checking if an Ursula is accessible from another Ursula

nucypher/network/middleware.py

@@ -21,18 +21,15 @@ import ssl
 
 import requests
 import time
+from bytestring_splitter import BytestringSplitter, VariableLengthBytestring
 from constant_sorrow.constants import CERTIFICATE_NOT_SAVED, EXEMPT_FROM_VERIFICATION
-
-
 from cryptography import x509
 from cryptography.hazmat.backends import default_backend
 from twisted.logger import Logger
+
 from umbral.cfrags import CapsuleFrag
 from umbral.signing import Signature
 
-from bytestring_splitter import BytestringSplitter, VariableLengthBytestring
-
-
 EXEMPT_FROM_VERIFICATION.bool_value(False)
 
 
@@ -234,6 +231,22 @@ class RestMiddleware:
             path=f"kFrag/{id_as_hex}/reencrypt",
             data=payload, timeout=2)
 
+    def node_information(self, host, port, certificate_filepath=None):
+        response = self.client.get(host=host, port=port,
+                                   path="public_information",
+                                   timeout=2,
+                                   certificate_filepath=certificate_filepath)
+        return response.content
+
+    def ping(self, host, port, certificate_filepath=None):
+        response = self.client.get(host=host, port=port,
+                                   path="ping",
+                                   timeout=2,
+                                   certificate_filepath=certificate_filepath)
+        if response.status_code != 200:
+            raise RuntimeError("Your node could not successfully be pinged from the remote node.")
+        return True
+
     def get_nodes_via_rest(self,
                            node,
                            announce_nodes=None,

nucypher/network/server.py

@@ -19,14 +19,18 @@ import binascii
 import os
 from typing import Tuple
 
+import requests
 from bytestring_splitter import BytestringSplitter
 from constant_sorrow import constants
-from constant_sorrow.constants import FLEET_STATES_MATCH, NO_KNOWN_NODES, NO_BLOCKCHAIN_CONNECTION
-from flask import Flask, Response, jsonify
-from flask import request
+from constant_sorrow.constants import FLEET_STATES_MATCH, NO_KNOWN_NODES
+from constant_sorrow.constants import NO_BLOCKCHAIN_CONNECTION
+from flask import Flask, Response, request
+from flask import jsonify
 from hendrix.experience import crosstown_traffic
 from jinja2 import Template, TemplateError
 from twisted.logger import Logger
+from umbral.keys import UmbralPublicKey
+from umbral.kfrags import KFrag
 from web3.exceptions import TimeExhausted
 
 import nucypher
@@ -41,8 +45,6 @@ from nucypher.datastore.threading import ThreadedSession
 from nucypher.network import LEARNING_LOOP_VERSION
 from nucypher.network.exceptions import NodeSeemsToBeDown
 from nucypher.network.protocols import InterfaceInfo
-from umbral.keys import UmbralPublicKey
-from umbral.kfrags import KFrag
 
 HERE = BASE_DIR = os.path.abspath(os.path.dirname(__file__))
 TEMPLATES_DIR = os.path.join(HERE, "templates")
@@ -121,6 +123,26 @@ def make_rest_app(
 
         return response
 
+    @rest_app.route("/ping")
+    def ping():
+        """
+        Returns network information about the accessor's connection to
+        the node.
+        TODO: Parameterize the port.
+        TODO: Fix certificate verification check so we don't pass verify=False
+        TODO: Figure out how to test this.
+        """
+        node_ip = request.environ['REMOTE_ADDR']
+
+        try:
+            result = requests.get(f"https://{node_ip}:9151/public_information", verify=False)
+        except requests.exceptions.ConnectionError:
+            return Response(status=400)
+
+        if result.status_code != 200:
+            return Response(status=400)
+        return Response(status=200)
+
     @rest_app.route('/node_metadata', methods=["GET"])
     def all_known_nodes():
         headers = {'Content-Type': 'application/octet-stream'}