resolve domains directly against dyn nameserver (instead of system resolver)

[dyn-nsupdate.git] / client-scripts / dyn-ns-client

diff --git a/client-scripts/dyn-ns-client b/client-scripts/dyn-ns-client
index 88d92204e121fff6571d6dbf111aa4b9d2b09b75..124498a8d6940133bf3ab043fa1308502af3a7b8 100755 (executable)
--- a/client-scripts/dyn-ns-client
+++ b/client-scripts/dyn-ns-client
@@ -24,6 +24,7 @@
 #==============================================================================
 
 import urllib.request, socket, sys, argparse, os, configparser, itertools, subprocess, re, ssl
+import dns, dns.resolver
 
 VERBOSE_CHANGE = 1
 VERBOSE_FULL   = 2
@@ -51,9 +52,9 @@ def getConfigDir():
 
 def urlopen(url, config):
     if sys.version_info >= (3, 4, 3):
-        return urllib.request.urlopen(url, context=sslContext(config)).read().decode('utf-8').strip()
+        return urllib.request.urlopen(url, context=sslContext(config)).read().decode('utf-8').strip('\n')
     else:
-        return urllib.request.urlopen(url).read().decode('utf-8').strip()
+        return urllib.request.urlopen(url).read().decode('utf-8').strip('\n')
 
 def getMyIP(family, config, methods = {}, verbose = 0):
     '''Returns our current IP address (<family> can be "IPv4" or "IPv6"), detected as given by the configuration.
@@ -61,9 +62,15 @@ def getMyIP(family, config, methods = {}, verbose = 0):
     method = config[family]['method']
     if method == 'none':
         return None
+    elif method == 'remove':
+        return ""
     elif method == 'web':
         server = config[family].get('server', config['DEFAULT']['server'])
-        ip = urlopen('https://'+server+'/checkip', config)
+        url = 'https://'+server+'/checkip'
+        try:
+            ip = urlopen(url, config)
+        except urllib.error.URLError:
+            raise Exception("Error fetching {}, make sure the URL is correct and the internet connection actually works.".format(url))
         if verbose >= VERBOSE_FULL:
             print("Server",server,"says my",family,"is",ip)
         return ip
@@ -79,7 +86,8 @@ def getMyIPv4(config, verbose = 0):
 def getMyIPv6(config, verbose = 0):
     '''Returns our current IPv6 address, detected as given by the configuration'''
     def local():
-        out = subprocess.check_output(["ip", "addr"])
+        device = config["IPv6"].get("device")
+        out = subprocess.check_output(["ip", "addr", "show"] + ([] if device is None else ["dev", device]))
         for line in out.decode('utf-8').split('\n'):
             m = re.search('inet6 ([a-fA-F0-9:]+)/64 ([a-zA-Z0-9 ]*)', line)
             if m is not None:
@@ -92,22 +100,21 @@ def getMyIPv6(config, verbose = 0):
         raise Exception("Unable to detect correct local IPv6 address")
     return getMyIP("IPv6", config, methods={'local': local}, verbose=verbose)
 
-def getCurIP(domain, family):
-    '''Return the current IP of the given <domain>. <family> can be socket.AF_INET or socket.AF_INET6.'''
+def getResolver(server):
+    '''Return a resovler with the given server (defined by DNS name)'''
+    addr = socket.getaddrinfo(server, None, family=socket.AF_INET)
+    addr = addr[0][4][0]
+    res = dns.resolver.Resolver()
+    res.nameservers = [addr]
+    return res
+
+def getCurIP(domain, rtype, res):
+    '''Return the current IP of the given <domain>. <rtype> can be A or AAAA.'''
     try:
-        addr = socket.getaddrinfo(domain, None, family=family)
-        return addr[0][4][0]
-    except socket.gaierror: # domain not found
+        return res.query(domain, rtype)[0].address
+    except dns.exception.DNSException: # domain not found
         return ""
 
-def getCurIPv4(domain):
-    '''Returns the current IPv4 address of the given domain'''
-    return getCurIP(domain, socket.AF_INET)
-
-def getCurIPv6(domain):
-    '''Returns the current IPv6 address of the given domain'''
-    return getCurIP(domain, socket.AF_INET6)
-
 def updateDomain(server, domain, ipv4, ipv6, password, config, verbose):
     '''Update the given domain, using the server, password. ipv4 or ipv6 can be None to not update that record, or strings with the respective addresses.
        Updates ae only performed if necessary.
@@ -115,8 +122,11 @@ def updateDomain(server, domain, ipv4, ipv6, password, config, verbose):
     assert ipv4 is not None or ipv6 is not None
     
     # check what the domain is currently mapped to
-    curIPv4 = getCurIPv4(domain)
-    curIPv6 = getCurIPv6(domain)
+    res = getResolver(server)
+    if verbose >= VERBOSE_FULL:
+        print("Resolving names using {}".format(res.nameservers))
+    curIPv4 = getCurIP(domain, 'A', res)
+    curIPv6 = getCurIP(domain, 'AAAA', res)
     if verbose >= VERBOSE_FULL:
         print("Current status of domain {} is: IPv4 address '{}', IPv6 address '{}'".format(domain, curIPv4, curIPv6))
     
@@ -136,6 +146,8 @@ def updateDomain(server, domain, ipv4, ipv6, password, config, verbose):
     if ipv6 is not None:
         url += '&ipv6='+urllib.parse.quote(ipv6)
         expected += " "+ipv6
+    if verbose >= VERBOSE_FULL:
+        print("Request:",url)
     result = urlopen(url, config)
     
     # did everything go as planned?
@@ -143,16 +155,24 @@ def updateDomain(server, domain, ipv4, ipv6, password, config, verbose):
         if verbose >= VERBOSE_CHANGE:
             msg = "Successfully updated domain {} on {}:".format(domain, server)
             if ipv4 is not None:
-                msg += " IPv4={} -> {}".format(curIPv4, ipv4)
+                if curIPv4 == ipv4:
+                    msg += " IPv4={} (unchanged)".format(curIPv4)
+                else:
+                    msg += " IPv4={} -> {}".format(curIPv4, ipv4)
+            if ipv4 is not None and ipv6 is not None:
+                msg += ","
             if ipv6 is not None:
-                msg += " IPv6={} -> {}".format(curIPv6, ipv6)
+                if curIPv6 == ipv6:
+                    msg += " IPv6={} (unchanged)".format(curIPv6)
+                else:
+                    msg += " IPv6={} -> {}".format(curIPv6, ipv6)
             print(msg)
         # all went all right
         return True
     else:
         # Something went wrong
         print("Unexpected answer from server",server,"while updating",domain)
-        print(result)
+        print("Got '{}', expected '{}'".format(result, expected))
         return False
 
 if __name__ == "__main__":