Improve new dig() helper, and use it in dnsrecords diagnosis as well

data/hooks/diagnosis/12-dnsrecords.py

@@ -2,9 +2,9 @@
 
 import os
 
-from moulinette.utils.process import check_output
 from moulinette.utils.filesystem import read_file
 
+from yunohost.utils.network import dig
 from yunohost.diagnosis import Diagnoser
 from yunohost.domain import domain_list, _build_dns_conf, _get_maindomain
 
@@ -100,20 +100,14 @@ class DNSRecordsDiagnoser(Diagnoser):
             yield output
 
     def get_current_record(self, domain, name, type_):
-        if name == "@":
-            command = "dig +short @%s %s %s" % (self.resolver, type_, domain)
-        else:
-            command = "dig +short @%s %s %s.%s" % (self.resolver, type_, name, domain)
-        # FIXME : gotta handle case where this command fails ...
-        # e.g. no internet connectivity (dependency mechanism to good result from 'ip' diagosis ?)
-        # or the resolver is unavailable for some reason
-        output = check_output(command).strip().split("\n")
-        if len(output) == 0 or not output[0]:
+
+        query = "%s.%s" % (name, domain) if name != "@" else domain
+        success, answers = dig(query, type_, resolvers="force_external")
+
+        if success != "ok":
             return None
-        elif len(output) == 1:
-            return output[0]
         else:
-            return output
+            return answers[0] if len(answers) == 1 else answers
 
     def current_record_match_expected(self, r):
         if r["value"] is not None and r["current"] is None:

data/hooks/diagnosis/24-mail.py

@@ -164,7 +164,7 @@ class MailDiagnoser(Diagnoser):
                 query = subdomain + '.' + blacklist['dns_server']
 
                 # Do the DNS Query
-                status, answers = dig(query, 'A')
+                status, _ = dig(query, 'A')
                 if status != 'ok':
                     continue
 

src/yunohost/utils/network.py

@@ -25,6 +25,7 @@ import dns.resolver
 
 from moulinette.utils.network import download_text
 from moulinette.utils.process import check_output
+from moulinette.utils.filesystem import read_file
 
 logger = logging.getLogger('yunohost.utils.network')
 
@@ -85,22 +86,50 @@ def get_gateway():
     return addr.popitem()[1] if len(addr) == 1 else None
 
 
-def dig(qname, rdtype="A", timeout=5, resolvers=["127.0.0.1"], edns_size=1500):
+# Lazy dev caching to avoid re-reading the file multiple time when calling
+# dig() often during same yunohost operation
+external_resolvers_ = []
+
+
+def external_resolvers():
+
+    global external_resolvers_
+
+    if not external_resolvers_:
+        resolv_dnsmasq_conf = read_file("/etc/resolv.dnsmasq.conf").split("\n")
+        external_resolvers_ = [r.split(" ")[1] for r in resolv_dnsmasq_conf if r.startswith("nameserver")]
+
+    return external_resolvers_
+
+
+def dig(qname, rdtype="A", timeout=5, resolvers="local", edns_size=1500, full_answers=False):
     """
     Do a quick DNS request and avoid the "search" trap inside /etc/resolv.conf
     """
 
+    if resolvers == "local":
+        resolvers = ["127.0.0.1"]
+    elif resolvers == "force_external":
+        resolvers = external_resolvers()
+    else:
+        assert isinstance(resolvers, list)
+
     resolver = dns.resolver.Resolver(configure=False)
     resolver.use_edns(0, 0, edns_size)
     resolver.nameservers = resolvers
     resolver.timeout = timeout
     try:
         answers = resolver.query(qname, rdtype)
-    except (dns.resolver.NXDOMAIN, dns.resolver.NoNameservers, dns.resolver.NoAnswer,
-    dns.exception.Timeout) as e:
-        return ("nok", e.__class__.__name__, e)
+    except (dns.resolver.NXDOMAIN,
+            dns.resolver.NoNameservers,
+            dns.resolver.NoAnswer,
+            dns.exception.Timeout) as e:
+        return ("nok", (e.__class__.__name__, e))
 
-    return ("ok", [(answer.to_text(), answer) for answer in answers])
+    if not full_answers:
+        answers = [answer.to_text() for answer in answers]
+
+    return ("ok", answers)
 
 
 def _extract_inet(string, skip_netmask=False, skip_loopback=True):