/*       +------------------------------------+
 *       | Inspire Internet Relay Chat Daemon |
 *       +------------------------------------+
 *
 *  InspIRCd: (C) 2002-2007 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_config.h"
#include "configreader.h"
#include "inspircd.h"
#include "users.h"
#include "channels.h"
#include "modules.h"

#include "m_hash.h"

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

/* Used to vary the output a little more depending on the cloak keys */
static const char* xtab[] = {"F92E45D871BCA630", "A1B9D80C72E653F4", "1ABC078934DEF562", "ABCDEF5678901234"};

/** Handles user mode +x
 */
class CloakUser : public ModeHandler
{
	
	std::string prefix;
	unsigned int key1;
	unsigned int key2;
	unsigned int key3;
	unsigned int key4;
	Module* Sender;
	Module* HashProvider;

	/** This function takes a domain name string and returns just the last two domain parts,
	 * or the last domain part if only two are available. Failing that it just returns what it was given.
	 *
	 * For example, if it is passed "svn.inspircd.org" it will return ".inspircd.org".
	 * If it is passed "brainbox.winbot.co.uk" it will return ".co.uk",
	 * and if it is passed "localhost.localdomain" it will return ".localdomain".
	 * 
	 * This is used to ensure a significant part of the host is always cloaked (see Bug #216)
	 */
	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);
	}
	
 public:
	CloakUser(InspIRCd* Instance, Module* Source, Module* Hash) : ModeHandler(Instance, 'x', 0, 0, false, MODETYPE_USER, false), Sender(Source), HashProvider(Hash)
	{
	}

	ModeAction OnModeChange(userrec* source, userrec* dest, chanrec* channel, std::string &parameter, bool adding)
	{
		/* Only opers can change other users modes */
		if ((source != dest) && (!*source->oper))
			return MODEACTION_DENY;

		/* For remote clients, we dont take any action, we just allow it.
		 * The local server where they are will set their cloak instead.
		 */
		if (!IS_LOCAL(dest))
			return MODEACTION_ALLOW;

		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.
				 */

				char* n1 = strchr(dest->host,'.');
				char* n2 = strchr(dest->host,':');
			
				if (n1 || n2)
				{
					/* 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.
					 */

					unsigned int iv[] = { key1, key2, key3, key4 };
					std::string a = LastTwoDomainParts(dest->host);
					std::string b;

					/** Reset the Hash module, and send it our IV and hex table */
					HashResetRequest(Sender, HashProvider).Send();
					HashKeyRequest(Sender, HashProvider, iv).Send();
					HashHexRequest(Sender, HashProvider, xtab[(*dest->host) % 4]);

					/* Generate a cloak using specialized Hash */
					std::string hostcloak = prefix + "-" + std::string(HashSumRequest(Sender, HashProvider, dest->host).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,&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,&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,':')) ? Cloak4(dest->host) : Cloak6(dest->host));
#else
					in_addr testaddr;
					if ((inet_aton(dest->host,&testaddr) < 1) && (hostcloak.length() <= 64))
						/* Invalid ipv4 address, and ipv4 user (resolved host) */
						b = hostcloak;
					else
						/* Valid ipv4 address (not resolved) ipv4 user */
						b = Cloak4(dest->host);
#endif

					dest->ChangeDisplayedHost(b.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);
				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++)
		{
			octet[j] = seps.GetToken();
			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)
	{
		/* Theyre using 4in6 (YUCK). Translate as ipv4 cloak */
		if (!strncmp(ip, "0::ffff:", 8))
			return Cloak4(ip + 8);

		/* If we get here, yes it really is an ipv6 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() > 4)
			{
				/* 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(0,10));
				item = "";
			}
			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(0,10));
			item = "";
		}
		/* Stick them all together */
		return irc::stringjoiner(":", hashies, 0, hashies.size() - 1).GetJoined();
	}
	
	void DoRehash()
	{
		ConfigReader Conf(ServerInstance);
		key1 = key2 = key3 = key4 = 0;
		key1 = Conf.ReadInteger("cloak","key1",0,true);
		key2 = Conf.ReadInteger("cloak","key2",0,true);
		key3 = Conf.ReadInteger("cloak","key3",0,true);
		key4 = Conf.ReadInteger("cloak","key4",0,true);
		prefix = Conf.ReadValue("cloak","prefix",0);

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

		if (!key1 && !key2 && !key3 && !key4)
			throw ModuleException("You have not defined cloak keys for m_cloaking!!! THIS IS INSECURE AND SHOULD BE CHECKED!");
	}
};


class ModuleCloaking : public Module
{
 private:
	
 	CloakUser* cu;
	Module* HashModule;

 public:
	ModuleCloaking(InspIRCd* Me)
		: Module::Module(Me)
	{
		ServerInstance->UseInterface("HashRequest");

		/* Attempt to locate the md5 service provider, bail if we can't find it */
		HashModule = ServerInstance->FindModule("m_md5.so");
		if (!HashModule)
			throw ModuleException("Can't find m_md5.so. Please load m_md5.so before m_cloaking.so.");

		/* Create new mode handler object */
		cu = new CloakUser(ServerInstance, this, HashModule);

		/* Register it with the core */		
		if (!ServerInstance->AddMode(cu, 'x'))
			throw ModuleException("Could not add new modes!");

		OnRehash(NULL,"");
	}
	
	virtual ~ModuleCloaking()
	{
		ServerInstance->Modes->DelMode(cu);
		DELETE(cu);
		ServerInstance->DoneWithInterface("HashRequest");
	}
	
	virtual Version GetVersion()
	{
		// returns the version number of the module to be
		// listed in /MODULES
		return Version(1,1,0,2,VF_COMMON|VF_VENDOR,API_VERSION);
	}

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

	void Implements(char* List)
	{
		List[I_OnRehash] = 1;
	}
};

// stuff down here is the module-factory stuff. For basic modules you can ignore this.

class ModuleCloakingFactory : public ModuleFactory
{
 public:
	ModuleCloakingFactory()
	{
	}
	
	~ModuleCloakingFactory()
	{
	}
	
	virtual Module * CreateModule(InspIRCd* Me)
	{
		return new ModuleCloaking(Me);
	}
	
};


extern "C" void * init_module( void )
{
	return new ModuleCloakingFactory;
}