src/coremods/core_hostname_lookup.cpp

   1 /*
   2  * InspIRCd -- Internet Relay Chat Daemon
   3  *
   4  *   Copyright (C) 2013-2015 Attila Molnar <attilamolnar@hush.com>
   5  *   Copyright (C) 2013, 2017-2019 Sadie Powell <sadie@witchery.services>
   6  *   Copyright (C) 2013, 2016 Adam <Adam@anope.org>
   7  *
   8  * This file is part of InspIRCd.  InspIRCd is free software: you can
   9  * redistribute it and/or modify it under the terms of the GNU General Public
  10  * License as published by the Free Software Foundation, version 2.
  11  *
  12  * This program is distributed in the hope that it will be useful, but WITHOUT
  13  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
  14  * FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
  15  * details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  19  */
  20
  21
  22 #include "inspircd.h"
  23 #include "modules/dns.h"
  24
  25 namespace
  26 {
  27         LocalIntExt* dl;
  28 }
  29
  30 /** Derived from Resolver, and performs user forward/reverse lookups.
  31  */
  32 class UserResolver : public DNS::Request
  33 {
  34  private:
  35         /** UUID we are looking up */
  36         const std::string uuid;
  37
  38         /** Handles errors which happen during DNS resolution. */
  39         static void HandleError(LocalUser* user, const std::string& message)
  40         {
  41                 user->WriteNotice("*** " + message + "; using your IP address (" + user->GetIPString() + ") instead.");
  42
  43                 bool display_is_real = user->GetDisplayedHost() == user->GetRealHost();
  44                 user->ChangeRealHost(user->GetIPString(), display_is_real);
  45
  46                 dl->unset(user);
  47         }
  48
  49  public:
  50         /** Create a resolver.
  51          * @param mgr DNS Manager
  52          * @param me this module
  53          * @param user The user to begin lookup on
  54          * @param to_resolve The IP or host to resolve
  55          * @param qt The query type
  56          */
  57         UserResolver(DNS::Manager* mgr, Module* me, LocalUser* user, const std::string& to_resolve, DNS::QueryType qt)
  58                 : DNS::Request(mgr, me, to_resolve, qt)
  59                 , uuid(user->uuid)
  60         {
  61         }
  62
  63         /** Called on successful lookup
  64          * if a previous result has already come back.
  65          * @param r The finished query
  66          */
  67         void OnLookupComplete(const DNS::Query* r) CXX11_OVERRIDE
  68         {
  69                 LocalUser* bound_user = IS_LOCAL(ServerInstance->FindUUID(uuid));
  70                 if (!bound_user)
  71                 {
  72                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Resolution finished for user '%s' who is gone", uuid.c_str());
  73                         return;
  74                 }
  75
  76                 const DNS::ResourceRecord* ans_record = r->FindAnswerOfType(this->question.type);
  77                 if (ans_record == NULL)
  78                 {
  79                         HandleError(bound_user, "Could not resolve your hostname: No " + this->manager->GetTypeStr(this->question.type) + " records found");
  80                         return;
  81                 }
  82
  83                 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "DNS %s result for %s: '%s' -> '%s'%s",
  84                         this->manager->GetTypeStr(question.type).c_str(), uuid.c_str(),
  85                         ans_record->name.c_str(), ans_record->rdata.c_str(),
  86                         r->cached ? " (cached)" : "");
  87
  88                 if (this->question.type == DNS::QUERY_PTR)
  89                 {
  90                         UserResolver* res_forward;
  91                         if (bound_user->client_sa.family() == AF_INET6)
  92                         {
  93                                 /* IPV6 forward lookup */
  94                                 res_forward = new UserResolver(this->manager, this->creator, bound_user, ans_record->rdata, DNS::QUERY_AAAA);
  95                         }
  96                         else
  97                         {
  98                                 /* IPV4 lookup */
  99                                 res_forward = new UserResolver(this->manager, this->creator, bound_user, ans_record->rdata, DNS::QUERY_A);
 100                         }
 101                         try
 102                         {
 103                                 this->manager->Process(res_forward);
 104                         }
 105                         catch (DNS::Exception& e)
 106                         {
 107                                 delete res_forward;
 108                                 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Error in resolver: " + e.GetReason());
 109
 110                                 HandleError(bound_user, "There was an internal error resolving your host");
 111                         }
 112                 }
 113                 else if (this->question.type == DNS::QUERY_A || this->question.type == DNS::QUERY_AAAA)
 114                 {
 115                         /* Both lookups completed */
 116
 117                         irc::sockets::sockaddrs* user_ip = &bound_user->client_sa;
 118                         bool rev_match = false;
 119                         if (user_ip->family() == AF_INET6)
 120                         {
 121                                 struct in6_addr res_bin;
 122                                 if (inet_pton(AF_INET6, ans_record->rdata.c_str(), &res_bin))
 123                                 {
 124                                         rev_match = !memcmp(&user_ip->in6.sin6_addr, &res_bin, sizeof(res_bin));
 125                                 }
 126                         }
 127                         else
 128                         {
 129                                 struct in_addr res_bin;
 130                                 if (inet_pton(AF_INET, ans_record->rdata.c_str(), &res_bin))
 131                                 {
 132                                         rev_match = !memcmp(&user_ip->in4.sin_addr, &res_bin, sizeof(res_bin));
 133                                 }
 134                         }
 135
 136                         if (rev_match)
 137                         {
 138                                 bound_user->WriteNotice("*** Found your hostname (" + this->question.name + (r->cached ? ") -- cached" : ")"));
 139                                 bool display_is_real = bound_user->GetDisplayedHost() == bound_user->GetRealHost();
 140                                 bound_user->ChangeRealHost(this->question.name, display_is_real);
 141                                 dl->unset(bound_user);
 142                         }
 143                         else
 144                         {
 145                                 HandleError(bound_user, "Your hostname does not match up with your IP address");
 146                         }
 147                 }
 148         }
 149
 150         /** Called on failed lookup
 151          * @param query The errored query
 152          */
 153         void OnError(const DNS::Query* query) CXX11_OVERRIDE
 154         {
 155                 LocalUser* bound_user = IS_LOCAL(ServerInstance->FindUUID(uuid));
 156                 if (bound_user)
 157                         HandleError(bound_user, "Could not resolve your hostname: " + this->manager->GetErrorStr(query->error));
 158         }
 159 };
 160
 161 class ModuleHostnameLookup : public Module
 162 {
 163  private:
 164         LocalIntExt dnsLookup;
 165         dynamic_reference<DNS::Manager> DNS;
 166
 167  public:
 168         ModuleHostnameLookup()
 169                 : dnsLookup("dnsLookup", ExtensionItem::EXT_USER, this)
 170                 , DNS(this, "DNS")
 171         {
 172                 dl = &dnsLookup;
 173         }
 174
 175         void OnSetUserIP(LocalUser* user) CXX11_OVERRIDE
 176         {
 177                 // If core_dns is not loaded or hostname resolution is disabled for the user's
 178                 // connect class then the logic in this function does not apply.
 179                 if (!DNS || !user->MyClass->resolvehostnames)
 180                         return;
 181
 182                 // Clients can't have a DNS hostname if they aren't connected via IPv4 or IPv6.
 183                 if (user->client_sa.family() != AF_INET && user->client_sa.family() != AF_INET6)
 184                         return;
 185
 186                 user->WriteNotice("*** Looking up your hostname...");
 187
 188                 UserResolver* res_reverse = new UserResolver(*this->DNS, this, user, user->GetIPString(), DNS::QUERY_PTR);
 189                 try
 190                 {
 191                         /* If both the reverse and forward queries are cached, the user will be able to pass DNS completely
 192                          * before Process() completes, which is why dnsLookup.set() is here, before Process()
 193                          */
 194                         this->dnsLookup.set(user, 1);
 195                         this->DNS->Process(res_reverse);
 196                 }
 197                 catch (DNS::Exception& e)
 198                 {
 199                         this->dnsLookup.set(user, 0);
 200                         delete res_reverse;
 201                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Error in resolver: " + e.GetReason());
 202                 }
 203         }
 204
 205         ModResult OnCheckReady(LocalUser* user) CXX11_OVERRIDE
 206         {
 207                 return this->dnsLookup.get(user) ? MOD_RES_DENY : MOD_RES_PASSTHRU;
 208         }
 209
 210         Version GetVersion() CXX11_OVERRIDE
 211         {
 212                 return Version("Provides support for DNS lookups on connecting clients", VF_CORE|VF_VENDOR);
 213         }
 214 };
 215
 216 MODULE_INIT(ModuleHostnameLookup)