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m_cloaking.cpp

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/*       +------------------------------------+
 *       | Inspire Internet Relay Chat Daemon |
 *       +------------------------------------+
 *
 *  InspIRCd: (C) 2002-2008 InspIRCd Development Team
 * See: http://www.inspircd.org/wiki/index.php/Credits
 *
 * This program is free but copyrighted software; see
 *          the file COPYING for details.
 *
 * ---------------------------------------------------
 */

#include "inspircd.h"
#include "m_hash.h"

/* $ModDesc: Provides masking of user hostnames */
/* $ModDep: m_hash.h */

class CloakUser : public ModeHandler
{
 public:
        std::string prefix;
        unsigned int key1;
        unsigned int key2;
        unsigned int key3;
        unsigned int key4;
        bool ipalways;
        Module* Sender;
        Module* HashProvider;
        const char *xtab[4];

        std::string LastTwoDomainParts(const std::string &host)
        {
                int dots = 0;
                std::string::size_type splitdot = host.length();

                for (std::string::size_type x = host.length() - 1; x; --x)
                {
                        if (host[x] == '.')
                        {
                                splitdot = x;
                                dots++;
                        }
                        if (dots >= 3)
                                break;
                }

                if (splitdot == host.length())
                        return host;
                else
                        return host.substr(splitdot);
        }

        CloakUser(InspIRCd* Instance, Module* source, Module* Hash) : ModeHandler(Instance, 'x', 0, 0, false, MODETYPE_USER, false), Sender(source), HashProvider(Hash)
        {
        }

        ModeAction OnModeChange(User* source, User* dest, Channel* channel, std::string &parameter, bool adding, bool)
        {
                /* For remote clients, we dont take any action, we just allow it.
                 * The local server where they are will set their cloak instead.
                 * This is fine, as we will recieve it later.
                 */
                if (!IS_LOCAL(dest))
                {
                        dest->SetMode('x',adding);
                        return MODEACTION_ALLOW;
                }

                /* don't allow this user to spam modechanges */
                dest->IncreasePenalty(5);

                if (adding)
                {
                        if(!dest->IsModeSet('x'))
                        {
                                /* The mode is being turned on - so attempt to
                                 * allocate the user a cloaked host using a non-reversible
                                 * algorithm (its simple, but its non-reversible so the
                                 * simplicity doesnt really matter). This algorithm
                                 * will not work if the user has only one level of domain
                                 * naming in their hostname (e.g. if they are on a lan or
                                 * are connecting via localhost) -- this doesnt matter much.
                                 */

                                std::string* cloak;

                                if (!dest->GetExt("cloaked_host", cloak))
                                {
                                        /* Force creation of missing cloak */
                                        Sender->OnUserConnect(dest);
                                }
                                if (dest->GetExt("cloaked_host", cloak))
                                {
                                        dest->ChangeDisplayedHost(cloak->c_str());
                                        dest->SetMode('x',true);
                                        return MODEACTION_ALLOW;
                                }
                        }
                }
                else
                {
                        if (dest->IsModeSet('x'))
                        {
                                /* User is removing the mode, so just restore their real host
                                 * and make it match the displayed one.
                                 */
                                dest->ChangeDisplayedHost(dest->host.c_str());
                                dest->SetMode('x',false);
                                return MODEACTION_ALLOW;
                        }
                }

                return MODEACTION_DENY;
        }

        std::string Cloak4(const char* ip)
        {
                unsigned int iv[] = { key1, key2, key3, key4 };
                irc::sepstream seps(ip, '.');
                std::string ra[4];;
                std::string octet[4];
                int i[4];

                for (int j = 0; j < 4; j++)
                {
                        seps.GetToken(octet[j]);
                        i[j] = atoi(octet[j].c_str());
                }

                octet[3] = octet[0] + "." + octet[1] + "." + octet[2] + "." + octet[3];
                octet[2] = octet[0] + "." + octet[1] + "." + octet[2];
                octet[1] = octet[0] + "." + octet[1];

                /* Reset the Hash module and send it our IV */
                HashResetRequest(Sender, HashProvider).Send();
                HashKeyRequest(Sender, HashProvider, iv).Send();

                /* Send the Hash module a different hex table for each octet group's Hash sum */
                for (int k = 0; k < 4; k++)
                {
                        HashHexRequest(Sender, HashProvider, xtab[(iv[k]+i[k]) % 4]).Send();
                        ra[k] = std::string(HashSumRequest(Sender, HashProvider, octet[k]).Send()).substr(0,6);
                }
                /* Stick them all together */
                return std::string().append(ra[0]).append(".").append(ra[1]).append(".").append(ra[2]).append(".").append(ra[3]);
        }

        std::string Cloak6(const char* ip)
        {
                unsigned int iv[] = { key1, key2, key3, key4 };
                std::vector<std::string> hashies;
                std::string item;
                int rounds = 0;

                /* Reset the Hash module and send it our IV */
                HashResetRequest(Sender, HashProvider).Send();
                HashKeyRequest(Sender, HashProvider, iv).Send();

                for (const char* input = ip; *input; input++)
                {
                        item += *input;
                        if (item.length() > 7)
                        {
                                /* Send the Hash module a different hex table for each octet group's Hash sum */
                                HashHexRequest(Sender, HashProvider, xtab[(key1+rounds) % 4]).Send();
                                hashies.push_back(std::string(HashSumRequest(Sender, HashProvider, item).Send()).substr(0,8));
                                item.clear();
                        }
                        rounds++;
                }
                if (!item.empty())
                {
                        /* Send the Hash module a different hex table for each octet group's Hash sum */
                        HashHexRequest(Sender, HashProvider, xtab[(key1+rounds) % 4]).Send();
                        hashies.push_back(std::string(HashSumRequest(Sender, HashProvider, item).Send()).substr(0,8));
                        item.clear();
                }
                /* Stick them all together */
                return irc::stringjoiner(":", hashies, 0, hashies.size() - 1).GetJoined();
        }

        void DoRehash()
        {
                ConfigReader Conf(ServerInstance);
                bool lowercase;

                /* These are *not* using the need_positive parameter of ReadInteger -
                 * that will limit the valid values to only the positive values in a
                 * signed int. Instead, accept any value that fits into an int and
                 * cast it to an unsigned int. That will, a bit oddly, give us the full
                 * spectrum of an unsigned integer. - Special */
                key1 = key2 = key3 = key4 = 0;
                key1 = (unsigned int) Conf.ReadInteger("cloak","key1",0,false);
                key2 = (unsigned int) Conf.ReadInteger("cloak","key2",0,false);
                key3 = (unsigned int) Conf.ReadInteger("cloak","key3",0,false);
                key4 = (unsigned int) Conf.ReadInteger("cloak","key4",0,false);
                prefix = Conf.ReadValue("cloak","prefix",0);
                ipalways = Conf.ReadFlag("cloak", "ipalways", 0);
                lowercase = Conf.ReadFlag("cloak", "lowercase", 0);

                if (!lowercase)
                {
                        xtab[0] = "F92E45D871BCA630";
                        xtab[1] = "A1B9D80C72E653F4";
                        xtab[2] = "1ABC078934DEF562";
                        xtab[3] = "ABCDEF5678901234";
                }
                else
                {
                        xtab[0] = "f92e45d871bca630";
                        xtab[1] = "a1b9d80c72e653f4";
                        xtab[2] = "1abc078934def562";
                        xtab[3] = "abcdef5678901234";
                }

                if (prefix.empty())
                        prefix = ServerInstance->Config->Network;

                if (!key1 || !key2 || !key3 || !key4)
                {
                        std::string detail;
                        if (!key1)
                                detail = "<cloak:key1> is not valid, it may be set to a too high/low value, or it may not exist.";
                        else if (!key2)
                                detail = "<cloak:key2> is not valid, it may be set to a too high/low value, or it may not exist.";
                        else if (!key3)
                                detail = "<cloak:key3> is not valid, it may be set to a too high/low value, or it may not exist.";
                        else if (!key4)
                                detail = "<cloak:key4> is not valid, it may be set to a too high/low value, or it may not exist.";

                        throw ModuleException("You have not defined cloak keys for m_cloaking!!! THIS IS INSECURE AND SHOULD BE CHECKED! - " + detail);
                }
        }
};


class ModuleCloaking : public Module
{
 private:

        CloakUser* cu;
        Module* HashModule;

 public:
        ModuleCloaking(InspIRCd* Me)
                : Module(Me)
        {
                /* Attempt to locate the md5 service provider, bail if we can't find it */
                HashModule = ServerInstance->Modules->Find("m_md5.so");
                if (!HashModule)
                        throw ModuleException("Can't find m_md5.so. Please load m_md5.so before m_cloaking.so.");

                cu = new CloakUser(ServerInstance, this, HashModule);

                try
                {
                        OnRehash(NULL,"");
                }
                catch (ModuleException &e)
                {
                        delete cu;
                        throw e;
                }

                /* Register it with the core */
                if (!ServerInstance->Modes->AddMode(cu))
                {
                        delete cu;
                        throw ModuleException("Could not add new modes!");
                }

                ServerInstance->Modules->UseInterface("HashRequest");

                Implementation eventlist[] = { I_OnRehash, I_OnUserDisconnect, I_OnCleanup, I_OnCheckBan, I_OnUserConnect, I_OnSyncUserMetaData, I_OnCleanup };
                ServerInstance->Modules->Attach(eventlist, this, 6);

                CloakExistingUsers();
        }

        void OnSyncUserMetaData(User* user, Module* proto,void* opaque, const std::string &extname, bool displayable)
        {
                if ((displayable) && (extname == "cloaked_host"))
                {
                        std::string* cloak;
                        if (user->GetExt("cloaked_host", cloak))
                                proto->ProtoSendMetaData(opaque, TYPE_USER, user, extname, *cloak);
                }
        }

        void CloakExistingUsers()
        {
                std::string* cloak;
                for (std::vector<User*>::iterator u = ServerInstance->Users->local_users.begin(); u != ServerInstance->Users->local_users.end(); u++)
                {
                        if (!(*u)->GetExt("cloaked_host", cloak))
                        {
                                OnUserConnect(*u);
                        }
                }
        }

        virtual int OnCheckBan(User* user, Channel* chan)
        {
                char mask[MAXBUF];
                std::string* tofree;
                /* Check if they have a cloaked host, but are not using it */
                if (user->GetExt("cloaked_host", tofree) && *tofree != user->dhost)
                {
                        snprintf(mask, MAXBUF, "%s!%s@%s", user->nick.c_str(), user->ident.c_str(), tofree->c_str());
                        for (BanList::iterator i = chan->bans.begin(); i != chan->bans.end(); i++)
                        {
                                if (InspIRCd::Match(mask,i->data))
                                        return -1;
                        }
                }
                return 0;
        }

        void Prioritize()
        {
                /* Needs to be after m_banexception etc. */
                ServerInstance->Modules->SetPriority(this, I_OnCheckBan, PRIO_LAST);

                /* but before m_conn_umodes, so host is generated ready to apply */
                Module *um = ServerInstance->Modules->Find("m_conn_umodes.so");
                ServerInstance->Modules->SetPriority(this, I_OnUserConnect, PRIO_AFTER, &um);
        }

        virtual void OnUserDisconnect(User* user)
        {
                std::string* tofree;
                if (user->GetExt("cloaked_host", tofree))
                {
                        delete tofree;
                        user->Shrink("cloaked_host");
                }
        }

        virtual void OnCleanup(int target_type, void* item)
        {
                if (target_type == TYPE_USER)
                        OnUserDisconnect((User*)item);
        }

        virtual ~ModuleCloaking()
        {
                ServerInstance->Modes->DelMode(cu);
                delete cu;
                ServerInstance->Modules->DoneWithInterface("HashRequest");
        }

        virtual Version GetVersion()
        {
                // returns the version number of the module to be
                // listed in /MODULES
                return Version("$Id: m_cloaking.cpp 10781 2008-11-01 20:20:12Z w00t $", VF_COMMON|VF_VENDOR,API_VERSION);
        }

        virtual void OnRehash(User* user, const std::string &parameter)
        {
                cu->DoRehash();
        }

        virtual void OnUserConnect(User* dest)
        {
                std::string* tofree;
                if (dest->GetExt("cloaked_host", tofree))
                        return;

                if (dest->host.find('.') != std::string::npos || dest->host.find(':') != std::string::npos)
                {
                        unsigned int iv[] = { cu->key1, cu->key2, cu->key3, cu->key4 };
                        std::string a = cu->LastTwoDomainParts(dest->host);
                        std::string b;

                        /* InspIRCd users have two hostnames; A displayed
                         * hostname which can be modified by modules (e.g.
                         * to create vhosts, implement chghost, etc) and a
                         * 'real' hostname which you shouldnt write to.
                         */

                        /* 2008/08/18: add <cloak:ipalways> which always cloaks
                         * the IP, for anonymity. --nenolod
                         */
                        if (!cu->ipalways)
                        {
                                HashResetRequest(this, cu->HashProvider).Send();
                                HashKeyRequest(this, cu->HashProvider, iv).Send();
                                HashHexRequest(this, cu->HashProvider, cu->xtab[(dest->host[0]) % 4]);

                                /* Generate a cloak using specialized Hash */
                                std::string hostcloak = cu->prefix + "-" + std::string(HashSumRequest(this, cu->HashProvider, dest->host.c_str()).Send()).substr(0,8) + a;

                                /* Fix by brain - if the cloaked host is > the max length of a host (64 bytes
                                 * according to the DNS RFC) then tough titty, they get cloaked as an IP.
                                 * Their ISP shouldnt go to town on subdomains, or they shouldnt have a kiddie
                                 * vhost.
                                 */
#ifdef IPV6
                                in6_addr testaddr;
                                in_addr testaddr2;
                                if ((dest->GetProtocolFamily() == AF_INET6) && (inet_pton(AF_INET6,dest->host.c_str(),&testaddr) < 1) && (hostcloak.length() <= 64))
                                        /* Invalid ipv6 address, and ipv6 user (resolved host) */
                                        b = hostcloak;
                                else if ((dest->GetProtocolFamily() == AF_INET) && (inet_aton(dest->host.c_str(),&testaddr2) < 1) && (hostcloak.length() <= 64))
                                        /* Invalid ipv4 address, and ipv4 user (resolved host) */
                                        b = hostcloak;
                                else
                                        /* Valid ipv6 or ipv4 address (not resolved) ipv4 or ipv6 user */
                                        b = ((!strchr(dest->host.c_str(),':')) ? cu->Cloak4(dest->host.c_str()) : cu->Cloak6(dest->host.c_str()));
#else
                                in_addr testaddr;
                                if ((inet_aton(dest->host.c_str(),&testaddr) < 1) && (hostcloak.length() <= 64))
                                        /* Invalid ipv4 address, and ipv4 user (resolved host) */
                                        b = hostcloak;
                                else
                                        /* Valid ipv4 address (not resolved) ipv4 user */
                                        b = cu->Cloak4(dest->host.c_str());
#endif
                        }
                        else
                        {
#ifdef IPV6
                                if (dest->GetProtocolFamily() == AF_INET6)
                                        b = cu->Cloak6(dest->GetIPString());
#endif
                                if (dest->GetProtocolFamily() == AF_INET)
                                        b = cu->Cloak4(dest->GetIPString());
                        }

                        dest->Extend("cloaked_host", new std::string(b));
                }
        }

};

MODULE_INIT(ModuleCloaking)