discovery service: dynamically replace 0.0.0.0 endpointUrl in server response

opcua/server/internal_server.py

@@ -4,11 +4,14 @@
 """
 
 from datetime import datetime, timedelta
-from copy import copy
+from copy import deepcopy
 import os
 import logging
 from threading import Lock
 from enum import Enum
+from socket import INADDR_ANY # IPv4 '0.0.0.0'
+IN6ADDR_ANY = '::'
+from ipaddress import ip_address
 try:
     from urllib.parse import urlparse
 except ImportError:
@@ -168,19 +171,47 @@ def add_endpoint(self, endpoint):
 
     def get_endpoints(self, params=None, sockname=None):
         self.logger.info("get endpoint")
-        if sockname:
-            # return to client the ip address it has access to
-            edps = []
-            for edp in self.endpoints:
-                edp1 = copy(edp)
-                url = urlparse(edp1.EndpointUrl)
-                url = url._replace(netloc=sockname[0] + ":" + str(sockname[1]))
-                edp1.EndpointUrl = url.geturl()
-                edps.append(edp1)
-            return edps
-        return self.endpoints[:]
+        # return to client the endpoints it has access to
+        netloc = self._get_netloc(params, sockname)
+        edps = deepcopy(self.endpoints)
+        for edp in edps:
+            edp.EndpointUrl = InternalServer._replace_inaddr_any(edp.EndpointUrl, netloc)
+        return edps
+
+    @staticmethod
+    def _get_netloc(params=None, sockname=None):
+        # find the ip:port as seen by our client.
+        netloc = None
+        if params and params.EndpointUrl:
+            # use ip:port as provided within client request params.
+            netloc = urlparse(params.EndpointUrl).netloc
+        if not netloc and sockname:
+            # use ip:port extracted from our local interface.
+            netloc = sockname[0] + ":" + str(sockname[1])
+        return netloc
+
+    @staticmethod
+    def _replace_inaddr_any(urlStr, netloc):
+        # If urlStr is '0.0.0.0:port' or '[::]:port', use netloc ip:port.
+        parseResult = urlparse(urlStr)
+        try:
+            hostip = ip_address(parseResult.hostname)
+        except ValueError:
+            hostip = None
+        if not netloc:
+            pass
+        elif hostip in (ip_address(INADDR_ANY), ip_address(IN6ADDR_ANY)):
+            urlStr = parseResult._replace(netloc=netloc).geturl()
+        return urlStr
 
     def find_servers(self, params):
+        servers = deepcopy(self._filter_servers(params))
+        netloc = self._get_netloc(params)
+        for srv in servers:
+            srv.DiscoveryUrls = [self._replace_inaddr_any(dUrl, netloc) for dUrl in srv.DiscoveryUrls]
+        return servers
+
+    def _filter_servers(self, params):
         if not params.ServerUris:
             return [desc.Server for desc in self._known_servers.values()]
         servers = []
@@ -311,7 +342,7 @@ def create_session(self, params, sockname=None):
         result.MaxRequestMessageSize = 65536
         self.nonce = utils.create_nonce(32)
         result.ServerNonce = self.nonce
-        result.ServerEndpoints = self.get_endpoints(sockname=sockname)
+        result.ServerEndpoints = self.get_endpoints(params=params, sockname=sockname)
 
         return result