Add DNS resolution tests

data/hooks/diagnosis/10-ip.py

@@ -28,16 +28,44 @@ class IPDiagnoser(Diagnoser):
 
         if 4 in versions:
 
+            # If we can't ping, there's not much else we can do
             if not self.can_ping_outside(4):
                 ipv4 = None
+            # If we do ping, check that we can resolv domain name
             else:
+                can_resolve_dns = self.can_resolve_dns()
+                # And if we do, then we can fetch the public ip
+                if can_resolve_dns:
                     ipv4 = self.get_public_ip(4)
 
+            # In every case, we can check that resolvconf seems to be okay
+            # (symlink managed by resolvconf service + pointing to dnsmasq)
+            good_resolvconf = self.resolvconf_is_symlink() and self.resolvconf_points_to_localhost()
+
+            # If we can't resolve domain names at all, that's a pretty big issue ...
+            # If it turns out that at the same time, resolvconf is bad, that's probably
+            # the cause of this, so we use a different message in that case
+            if not can_resolve_dns:
+                yield dict(meta = {"name": "dnsresolution"},
+                           status = "ERROR",
+                           summary = ("diagnosis_ip_broken_dnsresolution", {}) if good_resolvconf
+                                else ("diagnosis_ip_broken_resolvconf", {}))
+            # Otherwise, if the resolv conf is bad but we were able to resolve domain name,
+            # still warn that we're using a weird resolv conf ...
+            elif not good_resolvconf:
+                yield dict(meta = {"name": "dnsresolution"},
+                           status = "WARNING",
+                           summary = ("diagnosis_ip_weird_resolvconf", {}))
+            else:
+                # Well, maybe we could report a "success", "dns resolution is working", idk if it's worth it
+                pass
+
+            # And finally, we actually report the ipv4 connectivity stuff
             yield dict(meta = {"version": 4},
                        data = ipv4,
                        status = "SUCCESS" if ipv4 else "ERROR",
-                       summary = ("diagnosis_network_connected_ipv4", {}) if ipv4 \
-                            else ("diagnosis_network_no_ipv4", {}))
+                       summary = ("diagnosis_ip_connected_ipv4", {}) if ipv4 \
+                            else ("diagnosis_ip_no_ipv4", {}))
 
         if 6 in versions:
 
@@ -49,8 +77,8 @@ class IPDiagnoser(Diagnoser):
             yield dict(meta = {"version": 6},
                        data = ipv6,
                        status = "SUCCESS" if ipv6 else "WARNING",
-                       summary = ("diagnosis_network_connected_ipv6", {}) if ipv6 \
-                            else ("diagnosis_network_no_ipv6", {}))
+                       summary = ("diagnosis_ip_connected_ipv6", {}) if ipv6 \
+                            else ("diagnosis_ip_no_ipv6", {}))
 
 
     def can_ping_outside(self, protocol=4):
@@ -85,6 +113,20 @@ class IPDiagnoser(Diagnoser):
         random.shuffle(resolvers)
         return any(ping(protocol, resolver) for resolver in resolvers[:5])
 
+
+    def can_resolve_dns(self):
+        return os.system("dig +short ip.yunohost.org >/dev/null 2>/dev/null") == 0
+
+
+    def resolvconf_is_symlink(self):
+        return os.path.realpath("/etc/resolv.conf") == "/run/resolvconf/resolv.conf"
+
+    def resolvconf_points_to_localhost(self):
+        file_ = "/etc/resolv.conf"
+        resolvers = [r.split(" ")[1] for r in read_file(file_).split("\n") if r.startswith("nameserver")]
+        return resolvers == ["127.0.0.1"]
+
+
     def get_public_ip(self, protocol=4):
 
         # FIXME - TODO : here we assume that DNS resolution for ip.yunohost.org is working

locales/en.json

@@ -155,10 +155,13 @@
     "diagnosis_no_apps": "No installed application",
     "dpkg_is_broken": "You cannot do this right now because dpkg/APT (the system package managers) seems to be in a broken state… You can try to solve this issue by connecting through SSH and running `sudo dpkg --configure -a`.",
     "dpkg_lock_not_available": "This command can't be ran right now because another program seems to be using the lock of dpkg (the system package manager)",
-    "diagnosis_network_connected_ipv4": "The server is connected to the Internet through IPv4 !",
-    "diagnosis_network_no_ipv4": "The server does not have a working IPv4.",
-    "diagnosis_network_connected_ipv6": "The server is connect to the Internet through IPv6 !",
-    "diagnosis_network_no_ipv6": "The server does not have a working IPv6.",
+    "diagnosis_ip_connected_ipv4": "The server is connected to the Internet through IPv4 !",
+    "diagnosis_ip_no_ipv4": "The server does not have a working IPv4.",
+    "diagnosis_ip_connected_ipv6": "The server is connected to the Internet through IPv6 !",
+    "diagnosis_ip_no_ipv6": "The server does not have a working IPv6.",
+    "diagnosis_ip_broken_dnsresolution": "Domain name resolution seems to be broken for some reason ... Is a firewall blocking DNS requests ?",
+    "diagnosis_ip_broken_resolvconf": "Domain name resolution seems to be broken on your server, which seems related to /etc/resolv.conf not pointing to 127.0.0.1.",
+    "diagnosis_ip_weird_resolvconf": "Be careful that you seem to be using a custom /etc/resolv.conf. Instead, this file should be a symlink to /etc/resolvconf/run/resolv.conf itself pointing to 127.0.0.1 (dnsmasq).",
     "diagnosis_dns_good_conf": "Good DNS configuration for domain {domain} (category {category})",
     "diagnosis_dns_bad_conf": "Bad DNS configuration for domain {domain} (category {category})",
     "diagnosis_dns_missing_record": "According to the recommended DNS configuration, you should add a DNS record with type {0}, name {1} and value {2}",