[user/henk/code/inspircd.git] / src / modules / m_spanningtree / treesocket1.cpp

/*       +------------------------------------+
 *       | 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.h"
#include "configreader.h"
#include "users.h"
#include "channels.h"
#include "modules.h"
#include "commands/cmd_whois.h"
#include "commands/cmd_stats.h"
#include "socket.h"
#include "wildcard.h"
#include "xline.h"
#include "transport.h"
#include "m_hash.h"
#include "socketengine.h"

#include "m_spanningtree/main.h"
#include "m_spanningtree/utils.h"
#include "m_spanningtree/treeserver.h"
#include "m_spanningtree/link.h"
#include "m_spanningtree/treesocket.h"
#include "m_spanningtree/resolvers.h"
#include "m_spanningtree/handshaketimer.h"

/* $ModDep: m_spanningtree/timesynctimer.h m_spanningtree/resolvers.h m_spanningtree/main.h m_spanningtree/utils.h m_spanningtree/treeserver.h m_spanningtree/link.h m_spanningtree/treesocket.h m_hash.h */


/** Because most of the I/O gubbins are encapsulated within
 * InspSocket, we just call the superclass constructor for
 * most of the action, and append a few of our own values
 * to it.
 */
TreeSocket::TreeSocket(SpanningTreeUtilities* Util, InspIRCd* SI, std::string host, int port, bool listening, unsigned long maxtime, Module* HookMod)
        : InspSocket(SI, host, port, listening, maxtime), Utils(Util), Hook(HookMod)
{
        myhost = host;
        this->LinkState = LISTENER;
        theirchallenge.clear();
        ourchallenge.clear();
        if (listening && Hook)
                InspSocketHookRequest(this, (Module*)Utils->Creator, Hook).Send();
}

TreeSocket::TreeSocket(SpanningTreeUtilities* Util, InspIRCd* SI, std::string host, int port, bool listening, unsigned long maxtime, const std::string &ServerName, const std::string &bindto, Module* HookMod)
        : InspSocket(SI, host, port, listening, maxtime, bindto), Utils(Util), Hook(HookMod)
{
        myhost = ServerName;
        theirchallenge.clear();
        ourchallenge.clear();
        this->LinkState = CONNECTING;
        if (Hook)
                InspSocketHookRequest(this, (Module*)Utils->Creator, Hook).Send();
}

/** When a listening socket gives us a new file descriptor,
 * we must associate it with a socket without creating a new
 * connection. This constructor is used for this purpose.
 */
TreeSocket::TreeSocket(SpanningTreeUtilities* Util, InspIRCd* SI, int newfd, char* ip, Module* HookMod)
        : InspSocket(SI, newfd, ip), Utils(Util), Hook(HookMod)
{
        this->LinkState = WAIT_AUTH_1;
        theirchallenge.clear();
        ourchallenge.clear();
        /* If we have a transport module hooked to the parent, hook the same module to this
         * socket, and set a timer waiting for handshake before we send CAPAB etc.
         */
        if (Hook)
                InspSocketHookRequest(this, (Module*)Utils->Creator, Hook).Send();

        Instance->Timers->AddTimer(new HandshakeTimer(Instance, this, &(Utils->LinkBlocks[0]), this->Utils, 1));
}

ServerState TreeSocket::GetLinkState()
{
        return this->LinkState;
}

Module* TreeSocket::GetHook()
{
        return this->Hook;
}

TreeSocket::~TreeSocket()
{
        if (Hook)
                InspSocketUnhookRequest(this, (Module*)Utils->Creator, Hook).Send();

        Utils->DelBurstingServer(this);
}

const std::string& TreeSocket::GetOurChallenge()
{
        return this->ourchallenge;
}

void TreeSocket::SetOurChallenge(const std::string &c)
{
        this->ourchallenge = c;
}

const std::string& TreeSocket::GetTheirChallenge()
{
        return this->theirchallenge;
}

void TreeSocket::SetTheirChallenge(const std::string &c)
{
        this->theirchallenge = c;
}

std::string TreeSocket::MakePass(const std::string &password, const std::string &challenge)
{
        /* This is a simple (maybe a bit hacky?) HMAC algorithm, thanks to jilles for
         * suggesting the use of HMAC to secure the password against various attacks.
         *
         * Note: If m_sha256.so is not loaded, we MUST fall back to plaintext with no
         *       HMAC challenge/response.
         */
        Module* sha256 = Instance->FindModule("m_sha256.so");
        if (Utils->ChallengeResponse && sha256 && !challenge.empty())
        {
                /* XXX: This is how HMAC is supposed to be done:
                 *
                 * sha256( (pass xor 0x5c) + sha256((pass xor 0x36) + m) )
                 *
                 * Note that we are encoding the hex hash, not the binary
                 * output of the hash which is slightly different to standard.
                 *
                 * Don't ask me why its always 0x5c and 0x36... it just is.
                 */
                std::string hmac1, hmac2;

                for (size_t n = 0; n < password.length(); n++)
                {
                        hmac1 += static_cast<char>(password[n] ^ 0x5C);
                        hmac2 += static_cast<char>(password[n] ^ 0x36);
                }

                hmac2 += challenge;
                HashResetRequest(Utils->Creator, sha256).Send();
                hmac2 = HashSumRequest(Utils->Creator, sha256, hmac2).Send();

                HashResetRequest(Utils->Creator, sha256).Send();
                std::string hmac = hmac1 + hmac2;
                hmac = HashSumRequest(Utils->Creator, sha256, hmac).Send();

                return "HMAC-SHA256:"+ hmac;
        }
        else if (!challenge.empty() && !sha256)
                Instance->Log(DEFAULT,"Not authenticating to server using SHA256/HMAC because we don't have m_sha256 loaded!");

        return password;
}

/** When an outbound connection finishes connecting, we receive
 * this event, and must send our SERVER string to the other
 * side. If the other side is happy, as outlined in the server
 * to server docs on the inspircd.org site, the other side
 * will then send back its own server string.
 */
bool TreeSocket::OnConnected()
{
        if (this->LinkState == CONNECTING)
        {
                /* we do not need to change state here. */
                for (std::vector<Link>::iterator x = Utils->LinkBlocks.begin(); x < Utils->LinkBlocks.end(); x++)
                {
                        if (x->Name == this->myhost)
                        {
                                this->Instance->SNO->WriteToSnoMask('l',"Connection to \2"+myhost+"\2["+(x->HiddenFromStats ? "<hidden>" : this->GetIP())+"] started.");
                                if (Hook)
                                {
                                        InspSocketHookRequest(this, (Module*)Utils->Creator, Hook).Send();
                                        this->Instance->SNO->WriteToSnoMask('l',"Connection to \2"+myhost+"\2["+(x->HiddenFromStats ? "<hidden>" : this->GetIP())+"] using transport \2"+x->Hook+"\2");
                                }
                                this->OutboundPass = x->SendPass;

                                /* found who we're supposed to be connecting to, send the neccessary gubbins. */
                                if (this->GetHook())
                                        Instance->Timers->AddTimer(new HandshakeTimer(Instance, this, &(*x), this->Utils, 1));
                                else
                                        this->SendCapabilities();

                                return true;
                        }
                }
        }
        /* There is a (remote) chance that between the /CONNECT and the connection
         * being accepted, some muppet has removed the <link> block and rehashed.
         * If that happens the connection hangs here until it's closed. Unlikely
         * and rather harmless.
         */
        this->Instance->SNO->WriteToSnoMask('l',"Connection to \2"+myhost+"\2 lost link tag(!)");
        return true;
}

void TreeSocket::OnError(InspSocketError e)
{
        Link* MyLink;

        switch (e)
        {
                case I_ERR_CONNECT:
                        this->Instance->SNO->WriteToSnoMask('l',"Connection failed: Connection to \002"+myhost+"\002 refused");
                        MyLink = Utils->FindLink(myhost);
                        if (MyLink)
                                Utils->DoFailOver(MyLink);
                break;
                case I_ERR_SOCKET:
                        this->Instance->SNO->WriteToSnoMask('l',"Connection failed: Could not create socket");
                break;
                case I_ERR_BIND:
                        this->Instance->SNO->WriteToSnoMask('l',"Connection failed: Error binding socket to address or port");
                break;
                case I_ERR_WRITE:
                        this->Instance->SNO->WriteToSnoMask('l',"Connection failed: I/O error on connection");
                break;
                case I_ERR_NOMOREFDS:
                        this->Instance->SNO->WriteToSnoMask('l',"Connection failed: Operating system is out of file descriptors!");
                break;
                default:
                        if ((errno) && (errno != EINPROGRESS) && (errno != EAGAIN))
                        {
                                std::string errstr = strerror(errno);
                                this->Instance->SNO->WriteToSnoMask('l',"Connection to \002"+myhost+"\002 failed with OS error: " + errstr);
                        }
                break;
        }
}

int TreeSocket::OnDisconnect()
{
        /* For the same reason as above, we don't
         * handle OnDisconnect()
         */
        return true;
}

/** Recursively send the server tree with distances as hops.
 * This is used during network burst to inform the other server
 * (and any of ITS servers too) of what servers we know about.
 * If at any point any of these servers already exist on the other
 * end, our connection may be terminated. The hopcounts given
 * by this function are relative, this doesn't matter so long as
 * they are all >1, as all the remote servers re-calculate them
 * to be relative too, with themselves as hop 0.
 */
void TreeSocket::SendServers(TreeServer* Current, TreeServer* s, int hops)
{
        char command[1024];
        for (unsigned int q = 0; q < Current->ChildCount(); q++)
        {
                TreeServer* recursive_server = Current->GetChild(q);
                if (recursive_server != s)
                {
                        snprintf(command,1024,":%s SERVER %s * %d :%s",Current->GetName().c_str(),recursive_server->GetName().c_str(),hops,recursive_server->GetDesc().c_str());
                        this->WriteLine(command);
                        this->WriteLine(":"+recursive_server->GetName()+" VERSION :"+recursive_server->GetVersion());
                        /* down to next level */
                        this->SendServers(recursive_server, s, hops+1);
                }
        }
}

std::string TreeSocket::MyCapabilities()
{
        std::vector<std::string> modlist;
        std::string capabilities;
        for (int i = 0; i <= this->Instance->GetModuleCount(); i++)
        {
                if (this->Instance->modules[i]->GetVersion().Flags & VF_COMMON)
                        modlist.push_back(this->Instance->Config->module_names[i]);
        }
        sort(modlist.begin(),modlist.end());
        for (unsigned int i = 0; i < modlist.size(); i++)
        {
                if (i)
                        capabilities = capabilities + ",";
                capabilities = capabilities + modlist[i];
        }
        return capabilities;
}

std::string TreeSocket::RandString(unsigned int length)
{
        char* randombuf = new char[length+1];
        std::string out;
#ifdef WINDOWS
        int fd = -1;
#else
        int fd = open("/dev/urandom", O_RDONLY, 0);
#endif

        if (fd >= 0)
        {
#ifndef WINDOWS
                read(fd, randombuf, length);
                close(fd);
#endif
        }
        else
        {
                for (unsigned int i = 0; i < length; i++)
                        randombuf[i] = rand();
        }

        for (unsigned int i = 0; i < length; i++)
        {
                char randchar = static_cast<char>((randombuf[i] & 0x7F) | 0x21);
                out += (randchar == '=' ? '_' : randchar);
        }

        delete[] randombuf;
        return out;
}

void TreeSocket::SendCapabilities()
{
        irc::commasepstream modulelist(MyCapabilities());
        this->WriteLine("CAPAB START");

        /* Send module names, split at 509 length */
        std::string item = "*";
        std::string line = "CAPAB MODULES ";
        while ((item = modulelist.GetToken()) != "")
        {
                if (line.length() + item.length() + 1 > 509)
                {
                        this->WriteLine(line);
                        line = "CAPAB MODULES ";
                }

                if (line != "CAPAB MODULES ")
                        line.append(",");

                line.append(item);
        }
        if (line != "CAPAB MODULES ")
                this->WriteLine(line);

        int ip6 = 0;
        int ip6support = 0;
#ifdef IPV6
        ip6 = 1;
#endif
#ifdef SUPPORT_IP6LINKS
        ip6support = 1;
#endif
        std::string extra;
        /* Do we have sha256 available? If so, we send a challenge */
        if (Utils->ChallengeResponse && (Instance->FindModule("m_sha256.so")))
        {
                this->SetOurChallenge(RandString(20));
                extra = " CHALLENGE=" + this->GetOurChallenge();
        }

        this->WriteLine("CAPAB CAPABILITIES :NICKMAX="+ConvToStr(NICKMAX)+" HALFOP="+ConvToStr(this->Instance->Config->AllowHalfop)+" CHANMAX="+ConvToStr(CHANMAX)+" MAXMODES="+ConvToStr(MAXMODES)+" IDENTMAX="+ConvToStr(IDENTMAX)+" MAXQUIT="+ConvToStr(MAXQUIT)+" MAXTOPIC="+ConvToStr(MAXTOPIC)+" MAXKICK="+ConvToStr(MAXKICK)+" MAXGECOS="+ConvToStr(MAXGECOS)+" MAXAWAY="+ConvToStr(MAXAWAY)+" IP6NATIVE="+ConvToStr(ip6)+" IP6SUPPORT="+ConvToStr(ip6support)+" PROTOCOL="+ConvToStr(ProtocolVersion)+extra+" PREFIX="+Instance->Modes->BuildPrefixes()+" CHANMODES="+Instance->Modes->ChanModes());

        this->WriteLine("CAPAB END");
}

/* Check a comma seperated list for an item */
bool TreeSocket::HasItem(const std::string &list, const std::string &item)
{
        irc::commasepstream seplist(list);
        std::string item2 = "*";
        while ((item2 = seplist.GetToken()) != "")
        {
                if (item2 == item)
                        return true;
        }
        return false;
}

/* Isolate and return the elements that are different between two comma seperated lists */
std::string TreeSocket::ListDifference(const std::string &one, const std::string &two)
{
        irc::commasepstream list_one(one);
        std::string item = "*";
        std::string result;
        while ((item = list_one.GetToken()) != "")
        {
                if (!HasItem(two, item))
                {
                        result.append(" ");
                        result.append(item);
                }
        }
        return result;
}

void TreeSocket::SendError(const std::string &errormessage)
{
        /* Display the error locally as well as sending it remotely */
        this->WriteLine("ERROR :"+errormessage);
        this->Instance->SNO->WriteToSnoMask('l',"Sent \2ERROR\2 to "+this->InboundServerName+": "+errormessage);
        /* One last attempt to make sure the error reaches its target */
        this->FlushWriteBuffer();
}

bool TreeSocket::Capab(const std::deque<std::string> &params)
{
        if (params.size() < 1)
        {
                this->SendError("Invalid number of parameters for CAPAB - Mismatched version");
                return false;
        }
        if (params[0] == "START")
        {
                this->ModuleList.clear();
                this->CapKeys.clear();
        }
        else if (params[0] == "END")
        {
                std::string reason;
                int ip6support = 0;
#ifdef SUPPORT_IP6LINKS
                ip6support = 1;
#endif
                /* Compare ModuleList and check CapKeys...
                 * Maybe this could be tidier? -- Brain
                 */
                if ((this->ModuleList != this->MyCapabilities()) && (this->ModuleList.length()))
                {
                        std::string diff = ListDifference(this->ModuleList, this->MyCapabilities());
                        if (!diff.length())
                        {
                                diff = "your server:" + ListDifference(this->MyCapabilities(), this->ModuleList);
                        }
                        else
                        {
                                diff = "this server:" + diff;
                        }
                        if (diff.length() == 12)
                                reason = "Module list in CAPAB is not alphabetically ordered, cannot compare lists.";
                        else
                                reason = "Modules loaded on these servers are not correctly matched, these modules are not loaded on " + diff;
                }

                cap_validation valid_capab[] = { 
                        {"Maximum nickname lengths differ or remote nickname length not specified", "NICKMAX", NICKMAX},
                        {"Maximum ident lengths differ or remote ident length not specified", "IDENTMAX", IDENTMAX},
                        {"Maximum channel lengths differ or remote channel length not specified", "CHANMAX", CHANMAX},
                        {"Maximum modes per line differ or remote modes per line not specified", "MAXMODES", MAXMODES},
                        {"Maximum quit lengths differ or remote quit length not specified", "MAXQUIT", MAXQUIT},
                        {"Maximum topic lengths differ or remote topic length not specified", "MAXTOPIC", MAXTOPIC},
                        {"Maximum kick lengths differ or remote kick length not specified", "MAXKICK", MAXKICK},
                        {"Maximum GECOS (fullname) lengths differ or remote GECOS length not specified", "MAXGECOS", MAXGECOS},
                        {"Maximum awaymessage lengths differ or remote awaymessage length not specified", "MAXAWAY", MAXAWAY},
                        {"", "", 0}
                };

                if (((this->CapKeys.find("IP6SUPPORT") == this->CapKeys.end()) && (ip6support)) || ((this->CapKeys.find("IP6SUPPORT") != this->CapKeys.end()) && (this->CapKeys.find("IP6SUPPORT")->second != ConvToStr(ip6support))))
                        reason = "We don't both support linking to IPV6 servers";
                if (((this->CapKeys.find("IP6NATIVE") != this->CapKeys.end()) && (this->CapKeys.find("IP6NATIVE")->second == "1")) && (!ip6support))
                        reason = "The remote server is IPV6 native, and we don't support linking to IPV6 servers";
                if (((this->CapKeys.find("PROTOCOL") == this->CapKeys.end()) || ((this->CapKeys.find("PROTOCOL") != this->CapKeys.end()) && (this->CapKeys.find("PROTOCOL")->second != ConvToStr(ProtocolVersion)))))
                {
                        if (this->CapKeys.find("PROTOCOL") != this->CapKeys.end())
                                reason = "Mismatched protocol versions "+this->CapKeys.find("PROTOCOL")->second+" and "+ConvToStr(ProtocolVersion);
                        else
                                reason = "Protocol version not specified";
                }

                if (((this->CapKeys.find("HALFOP") == this->CapKeys.end()) && (Instance->Config->AllowHalfop)) || ((this->CapKeys.find("HALFOP") != this->CapKeys.end()) && (this->CapKeys.find("HALFOP")->second != ConvToStr(Instance->Config->AllowHalfop))))
                        reason = "We don't both have halfop support enabled/disabled identically";

                for (int x = 0; valid_capab[x].size; ++x)
                {
                        if (((this->CapKeys.find(valid_capab[x].key) == this->CapKeys.end()) || ((this->CapKeys.find(valid_capab[x].key) != this->CapKeys.end()) &&
                                                 (this->CapKeys.find(valid_capab[x].key)->second != ConvToStr(valid_capab[x].size)))))
                                reason = valid_capab[x].reason;
                }
        
                /* Challenge response, store their challenge for our password */
                std::map<std::string,std::string>::iterator n = this->CapKeys.find("CHALLENGE");
                if (Utils->ChallengeResponse && (n != this->CapKeys.end()) && (Instance->FindModule("m_sha256.so")))
                {
                        /* Challenge-response is on now */
                        this->SetTheirChallenge(n->second);
                        if (!this->GetTheirChallenge().empty() && (this->LinkState == CONNECTING))
                        {
                                this->WriteLine(std::string("SERVER ")+this->Instance->Config->ServerName+" "+this->MakePass(OutboundPass, this->GetTheirChallenge())+" 0 :"+this->Instance->Config->ServerDesc);
                        }
                }
                else
                {
                        /* They didnt specify a challenge or we don't have m_sha256.so, we use plaintext */
                        if (this->LinkState == CONNECTING)
                                this->WriteLine(std::string("SERVER ")+this->Instance->Config->ServerName+" "+OutboundPass+" 0 :"+this->Instance->Config->ServerDesc);
                }

                if (reason.length())
                {
                        this->SendError("CAPAB negotiation failed: "+reason);
                        return false;
                }
        }
        else if ((params[0] == "MODULES") && (params.size() == 2))
        {
                if (!this->ModuleList.length())
                {
                        this->ModuleList.append(params[1]);
                }
                else
                {
                        this->ModuleList.append(",");
                        this->ModuleList.append(params[1]);
                }
        }

        else if ((params[0] == "CAPABILITIES") && (params.size() == 2))
        {
                irc::tokenstream capabs(params[1]);
                std::string item;
                bool more = true;
                while ((more = capabs.GetToken(item)))
                {
                        /* Process each key/value pair */
                        std::string::size_type equals = item.rfind('=');
                        if (equals != std::string::npos)
                        {
                                std::string var = item.substr(0, equals);
                                std::string value = item.substr(equals+1, item.length());
                                CapKeys[var] = value;
                        }
                }
        }
        return true;
}

/** This function forces this server to quit, removing this server
 * and any users on it (and servers and users below that, etc etc).
 * It's very slow and pretty clunky, but luckily unless your network
 * is having a REAL bad hair day, this function shouldnt be called
 * too many times a month ;-)
 */
void TreeSocket::SquitServer(std::string &from, TreeServer* Current)
{
        /* recursively squit the servers attached to 'Current'.
         * We're going backwards so we don't remove users
         * while we still need them ;)
         */
        for (unsigned int q = 0; q < Current->ChildCount(); q++)
        {
                TreeServer* recursive_server = Current->GetChild(q);
                this->SquitServer(from,recursive_server);
        }
        /* Now we've whacked the kids, whack self */
        num_lost_servers++;
        num_lost_users += Current->QuitUsers(from);
}

/** This is a wrapper function for SquitServer above, which
 * does some validation first and passes on the SQUIT to all
 * other remaining servers.
 */
void TreeSocket::Squit(TreeServer* Current, const std::string &reason)
{
        if ((Current) && (Current != Utils->TreeRoot))
        {
                Event rmode((char*)Current->GetName().c_str(), (Module*)Utils->Creator, "lost_server");
                rmode.Send(Instance);

                std::deque<std::string> params;
                params.push_back(Current->GetName());
                params.push_back(":"+reason);
                Utils->DoOneToAllButSender(Current->GetParent()->GetName(),"SQUIT",params,Current->GetName());
                if (Current->GetParent() == Utils->TreeRoot)
                {
                        this->Instance->SNO->WriteToSnoMask('l',"Server \002"+Current->GetName()+"\002 split: "+reason);
                }
                else
                {
                        this->Instance->SNO->WriteToSnoMask('l',"Server \002"+Current->GetName()+"\002 split from server \002"+Current->GetParent()->GetName()+"\002 with reason: "+reason);
                }
                num_lost_servers = 0;
                num_lost_users = 0;
                std::string from = Current->GetParent()->GetName()+" "+Current->GetName();
                SquitServer(from, Current);
                Current->Tidy();
                Current->GetParent()->DelChild(Current);
                DELETE(Current);
                this->Instance->SNO->WriteToSnoMask('l',"Netsplit complete, lost \002%d\002 users on \002%d\002 servers.", num_lost_users, num_lost_servers);
        }
        else
                Instance->Log(DEFAULT,"Squit from unknown server");
}

/** FMODE command - server mode with timestamp checks */
bool TreeSocket::ForceMode(const std::string &source, std::deque<std::string> &params)
{
        /* Chances are this is a 1.0 FMODE without TS */
        if (params.size() < 3)
        {
                /* No modes were in the command, probably a channel with no modes set on it */
                return true;
        }

        bool smode = false;
        std::string sourceserv;
        /* Are we dealing with an FMODE from a user, or from a server? */
        userrec* who = this->Instance->FindNick(source);
        if (who)
        {
                /* FMODE from a user, set sourceserv to the users server name */
                sourceserv = who->server;
        }
        else
        {
                /* FMODE from a server, create a fake user to receive mode feedback */
                who = new userrec(this->Instance);
                who->SetFd(FD_MAGIC_NUMBER);
                smode = true;      /* Setting this flag tells us we should free the userrec later */
                sourceserv = source;    /* Set sourceserv to the actual source string */
        }
        const char* modelist[64];
        time_t TS = 0;
        int n = 0;
        memset(&modelist,0,sizeof(modelist));
        for (unsigned int q = 0; (q < params.size()) && (q < 64); q++)
        {
                if (q == 1)
                {
                        /* The timestamp is in this position.
                         * We don't want to pass that up to the
                         * server->client protocol!
                         */
                        TS = atoi(params[q].c_str());
                }
                else
                {
                        /* Everything else is fine to append to the modelist */
                        modelist[n++] = params[q].c_str();
                }

        }
        /* Extract the TS value of the object, either userrec or chanrec */
        userrec* dst = this->Instance->FindNick(params[0]);
        chanrec* chan = NULL;
        time_t ourTS = 0;
        if (dst)
        {
                ourTS = dst->age;
        }
        else
        {
                chan = this->Instance->FindChan(params[0]);
                if (chan)
                {
                        ourTS = chan->age;
                }
                else
                        /* Oops, channel doesnt exist! */
                        return true;
        }

        /* TS is equal or less: Merge the mode changes into ours and pass on.
         */
        if (TS <= ourTS)
        {
                if ((TS < ourTS) && (!dst))
                        Instance->Log(DEFAULT,"*** BUG *** Channel TS sent in FMODE to %s is %lu which is not equal to %lu!", params[0].c_str(), TS, ourTS);

                if (smode)
                {
                        this->Instance->SendMode(modelist, n, who);
                }
                else
                {
                        this->Instance->CallCommandHandler("MODE", modelist, n, who);
                }
                /* HOT POTATO! PASS IT ON! */
                Utils->DoOneToAllButSender(source,"FMODE",params,sourceserv);
        }
        /* If the TS is greater than ours, we drop the mode and dont pass it anywhere.
         */

        if (smode)
                DELETE(who);

        return true;
}

/** FTOPIC command */
bool TreeSocket::ForceTopic(const std::string &source, std::deque<std::string> &params)
{
        if (params.size() != 4)
                return true;
        time_t ts = atoi(params[1].c_str());
        std::string nsource = source;
        chanrec* c = this->Instance->FindChan(params[0]);
        if (c)
        {
                if ((ts >= c->topicset) || (!*c->topic))
                {
                        std::string oldtopic = c->topic;
                        strlcpy(c->topic,params[3].c_str(),MAXTOPIC);
                        strlcpy(c->setby,params[2].c_str(),127);
                        c->topicset = ts;
                        /* if the topic text is the same as the current topic,
                         * dont bother to send the TOPIC command out, just silently
                         * update the set time and set nick.
                         */
                        if (oldtopic != params[3])
                        {
                                userrec* user = this->Instance->FindNick(source);
                                if (!user)
                                {
                                        c->WriteChannelWithServ(Instance->Config->ServerName, "TOPIC %s :%s", c->name, c->topic);
                                }
                                else
                                {
                                        c->WriteChannel(user, "TOPIC %s :%s", c->name, c->topic);
                                        nsource = user->server;
                                }
                                /* all done, send it on its way */
                                params[3] = ":" + params[3];
                                Utils->DoOneToAllButSender(source,"FTOPIC",params,nsource);
                        }
                }

        }
        return true;
}

/** FJOIN, similar to TS6 SJOIN, but not quite. */
bool TreeSocket::ForceJoin(const std::string &source, std::deque<std::string> &params)
{
        /* 1.1 FJOIN works as follows:
         *
         * Each FJOIN is sent along with a timestamp, and the side with the lowest
         * timestamp 'wins'. From this point on we will refer to this side as the
         * winner. The side with the higher timestamp loses, from this point on we
         * will call this side the loser or losing side. This should be familiar to
         * anyone who's dealt with dreamforge or TS6 before.
         *
         * When two sides of a split heal and this occurs, the following things
         * will happen:
         *
         * If the timestamps are exactly equal, both sides merge their privilages
         * and users, as in InspIRCd 1.0 and ircd2.8. The channels have not been
         * re-created during a split, this is safe to do.
         *
         * If the timestamps are NOT equal, the losing side removes all of its
         * modes from the channel, before introducing new users into the channel
         * which are listed in the FJOIN command's parameters. The losing side then
         * LOWERS its timestamp value of the channel to match that of the winning
         * side, and the modes of the users of the winning side are merged in with
         * the losing side.
         *
         * The winning side on the other hand will ignore all user modes from the
         * losing side, so only its own modes get applied. Life is simple for those
         * who succeed at internets. :-)
         *
         * NOTE: Unlike TS6 and dreamforge and other protocols which have SJOIN,
         * FJOIN does not contain the simple-modes such as +iklmnsp. Why not,
         * you ask? Well, quite simply because we don't need to. They'll be sent
         * after the FJOIN by FMODE, and FMODE is timestamped, so in the event
         * the losing side sends any modes for the channel which shouldnt win,
         * they wont as their timestamp will be too high :-)
         */

        if (params.size() < 3)
                return true;

        irc::modestacker modestack(true);                               /* Modes to apply from the users in the user list */
        userrec* who = NULL;                                            /* User we are currently checking */
        std::string channel = params[0];                                /* Channel name, as a string */
        time_t TS = atoi(params[1].c_str());                            /* Timestamp given to us for remote side */
        irc::tokenstream users(params[2]);                              /* Users from the user list */
        bool apply_other_sides_modes = true;                            /* True if we are accepting the other side's modes */
        chanrec* chan = this->Instance->FindChan(channel);              /* The channel we're sending joins to */
        time_t ourTS = chan ? chan->age : Instance->Time(true)+600;     /* The TS of our side of the link */
        bool created = !chan;                                           /* True if the channel doesnt exist here yet */
        std::string item;                                               /* One item in the list of nicks */

        params[2] = ":" + params[2];
        Utils->DoOneToAllButSender(source,"FJOIN",params,source);

        /* If our TS is less than theirs, we dont accept their modes */
        if (ourTS < TS)
                apply_other_sides_modes = false;

        /* Our TS greater than theirs, clear all our modes from the channel, accept theirs. */
        if (ourTS > TS)
        {
                std::deque<std::string> param_list;
                if (Utils->AnnounceTSChange && chan)
                        chan->WriteChannelWithServ(Instance->Config->ServerName, "NOTICE %s :TS for %s changed from %lu to %lu", chan->name, chan->name, ourTS, TS);
                ourTS = TS;
                if (!created)
                {
                        chan->age = TS;
                        param_list.push_back(channel);
                        this->RemoveStatus(Instance->Config->ServerName, param_list);
                }
        }

        /* Now, process every 'prefixes,nick' pair */
        while (users.GetToken(item))
        {
                const char* usr = item.c_str();
                if (usr && *usr)
                {
                        const char* permissions = usr;
                        /* Iterate through all the prefix values, convert them from prefixes to mode letters */
                        std::string modes;
                        while ((*permissions) && (*permissions != ','))
                        {
                                ModeHandler* mh = Instance->Modes->FindPrefix(*permissions);
                                if (mh)
                                        modes = modes + mh->GetModeChar();
                                else
                                {
                                        this->SendError(std::string("Invalid prefix '")+(*permissions)+"' in FJOIN");
                                        return false;
                                }
                                usr++;
                                permissions++;
                        }
                        /* Advance past the comma, to the nick */
                        usr++;
                        
                        /* Check the user actually exists */
                        who = this->Instance->FindNick(usr);
                        if (who)
                        {
                                /* Check that the user's 'direction' is correct */
                                TreeServer* route_back_again = Utils->BestRouteTo(who->server);
                                if ((!route_back_again) || (route_back_again->GetSocket() != this))
                                        continue;

                                /* Add any permissions this user had to the mode stack */
                                for (std::string::iterator x = modes.begin(); x != modes.end(); ++x)
                                        modestack.Push(*x, who->nick);

                                chanrec::JoinUser(this->Instance, who, channel.c_str(), true, "", TS);
                        }
                        else
                        {
                                Instance->Log(SPARSE,"Warning! Invalid user %s in FJOIN to channel %s IGNORED", usr, channel.c_str());
                                continue;
                        }
                }
        }

        /* Flush mode stacker if we lost the FJOIN or had equal TS */
        if (apply_other_sides_modes)
        {
                std::deque<std::string> stackresult;
                const char* mode_junk[MAXMODES+1];
                userrec* n = new userrec(Instance);
                n->SetFd(FD_MAGIC_NUMBER);
                mode_junk[0] = channel.c_str();

                while (modestack.GetStackedLine(stackresult))
                {
                        for (size_t j = 0; j < stackresult.size(); j++)
                        {
                                mode_junk[j+1] = stackresult[j].c_str();
                        }
                        Instance->SendMode(mode_junk, stackresult.size() + 1, n);
                }

                delete n;
        }

        return true;
}

/** NICK command */
bool TreeSocket::IntroduceClient(const std::string &source, std::deque<std::string> &params)
{
        /** Do we have enough parameters:
         * NICK age nick host dhost ident +modes ip :gecos
         */
        if (params.size() != 8)
        {
                this->WriteLine(std::string(":")+this->Instance->Config->ServerName+" KILL "+params[1]+" :Invalid client introduction ("+params[1]+"?)");
                return true;
        }

        time_t age = ConvToInt(params[0]);
        const char* tempnick = params[1].c_str();

        cmd_validation valid[] = { {"Nickname", 1, NICKMAX}, {"Hostname", 2, 64}, {"Displayed hostname", 3, 64}, {"Ident", 4, IDENTMAX}, {"GECOS", 7, MAXGECOS}, {"", 0, 0} };

        TreeServer* remoteserver = Utils->FindServer(source);
        if (!remoteserver)
        {
                this->WriteLine(std::string(":")+this->Instance->Config->ServerName+" KILL "+params[1]+" :Invalid client introduction (Unknown server "+source+")");
                return true;
        }

        /* Check parameters for validity before introducing the client, discovered by dmb */
        if (!age)
        {
                this->WriteLine(std::string(":")+this->Instance->Config->ServerName+" KILL "+params[1]+" :Invalid client introduction (Invalid TS?)");
                return true;
        }
        for (size_t x = 0; valid[x].length; ++x)
        {
                if (params[valid[x].param].length() > valid[x].length)
                {
                        this->WriteLine(std::string(":")+this->Instance->Config->ServerName+" KILL "+params[1]+" :Invalid client introduction (" + valid[x].item + " > " + ConvToStr(valid[x].length) + ")");
                        return true;
                }
        }

        /** Our client looks ok, lets introduce it now
         */
        Instance->Log(DEBUG,"New remote client %s",tempnick);
        user_hash::iterator iter = this->Instance->clientlist->find(tempnick);

        if (iter != this->Instance->clientlist->end())
        {
                /* nick collision */
                this->WriteLine(std::string(":")+this->Instance->Config->ServerName+" KILL "+tempnick+" :Nickname collision");
                userrec::QuitUser(this->Instance, iter->second, "Nickname collision");
                return true;
        }

        userrec* _new = new userrec(this->Instance);
        (*(this->Instance->clientlist))[tempnick] = _new;
        _new->SetFd(FD_MAGIC_NUMBER);
        strlcpy(_new->nick, tempnick,NICKMAX-1);
        strlcpy(_new->host, params[2].c_str(),64);
        strlcpy(_new->dhost, params[3].c_str(),64);
        _new->server = this->Instance->FindServerNamePtr(source.c_str());
        strlcpy(_new->ident, params[4].c_str(),IDENTMAX);
        strlcpy(_new->fullname, params[7].c_str(),MAXGECOS);
        _new->registered = REG_ALL;
        _new->signon = age;

        /* we need to remove the + from the modestring, so we can do our stuff */
        std::string::size_type pos_after_plus = params[5].find_first_not_of('+');
        if (pos_after_plus != std::string::npos)
        params[5] = params[5].substr(pos_after_plus);

        for (std::string::iterator v = params[5].begin(); v != params[5].end(); v++)
        {
                _new->modes[(*v)-65] = 1;
                /* For each mode thats set, increase counter */
                ModeHandler* mh = Instance->Modes->FindMode(*v, MODETYPE_USER);
                if (mh)
                        mh->ChangeCount(1);
        }

        /* now we've done with modes processing, put the + back for remote servers */
        params[5] = "+" + params[5];

#ifdef SUPPORT_IP6LINKS
        if (params[6].find_first_of(":") != std::string::npos)
                _new->SetSockAddr(AF_INET6, params[6].c_str(), 0);
        else
#endif
                _new->SetSockAddr(AF_INET, params[6].c_str(), 0);

        Instance->AddGlobalClone(_new);

        bool dosend = !(((this->Utils->quiet_bursts) && (this->bursting || Utils->FindRemoteBurstServer(remoteserver))) || (this->Instance->SilentULine(_new->server)));
        
        if (dosend)
                this->Instance->SNO->WriteToSnoMask('C',"Client connecting at %s: %s!%s@%s [%s] [%s]",_new->server,_new->nick,_new->ident,_new->host, _new->GetIPString(), _new->fullname);

        params[7] = ":" + params[7];
        Utils->DoOneToAllButSender(source,"NICK", params, source);

        // Increment the Source Servers User Count..
        TreeServer* SourceServer = Utils->FindServer(source);
        if (SourceServer)
        {
                SourceServer->AddUserCount();
        }

        FOREACH_MOD_I(Instance,I_OnPostConnect,OnPostConnect(_new));

        return true;
}

/** Send one or more FJOINs for a channel of users.
 * If the length of a single line is more than 480-NICKMAX
 * in length, it is split over multiple lines.
 */
void TreeSocket::SendFJoins(TreeServer* Current, chanrec* c)
{
        std::string buffer;
        char list[MAXBUF];
        std::string individual_halfops = std::string(":")+this->Instance->Config->ServerName+" FMODE "+c->name+" "+ConvToStr(c->age);

        size_t dlen, curlen;
        dlen = curlen = snprintf(list,MAXBUF,":%s FJOIN %s %lu",this->Instance->Config->ServerName,c->name,(unsigned long)c->age);
        int numusers = 0;
        char* ptr = list + dlen;

        CUList *ulist = c->GetUsers();
        std::string modes;
        std::string params;

        for (CUList::iterator i = ulist->begin(); i != ulist->end(); i++)
        {
                // The first parameter gets a : before it
                size_t ptrlen = snprintf(ptr, MAXBUF, " %s%s,%s", !numusers ? ":" : "", c->GetAllPrefixChars(i->first), i->first->nick);

                curlen += ptrlen;
                ptr += ptrlen;

                numusers++;

                if (curlen > (480-NICKMAX))
                {
                        buffer.append(list).append("\r\n");
                        dlen = curlen = snprintf(list,MAXBUF,":%s FJOIN %s %lu",this->Instance->Config->ServerName,c->name,(unsigned long)c->age);
                        ptr = list + dlen;
                        ptrlen = 0;
                        numusers = 0;
                }
        }

        if (numusers)
                buffer.append(list).append("\r\n");

        buffer.append(":").append(this->Instance->Config->ServerName).append(" FMODE ").append(c->name).append(" ").append(ConvToStr(c->age)).append(" +").append(c->ChanModes(true)).append("\r\n");

        int linesize = 1;
        for (BanList::iterator b = c->bans.begin(); b != c->bans.end(); b++)
        {
                int size = strlen(b->data) + 2;
                int currsize = linesize + size;
                if (currsize <= 350)
                {
                        modes.append("b");
                        params.append(" ").append(b->data);
                        linesize += size; 
                }
                if ((params.length() >= MAXMODES) || (currsize > 350))
                {
                        /* Wrap at MAXMODES */
                        buffer.append(":").append(this->Instance->Config->ServerName).append(" FMODE ").append(c->name).append(" ").append(ConvToStr(c->age)).append(" +").append(modes).append(params).append("\r\n");
                        modes.clear();
                        params.clear();
                        linesize = 1;
                }
        }

        /* Only send these if there are any */
        if (!modes.empty())
                buffer.append(":").append(this->Instance->Config->ServerName).append(" FMODE ").append(c->name).append(" ").append(ConvToStr(c->age)).append(" +").append(modes).append(params);

        this->WriteLine(buffer);
}

/** Send G, Q, Z and E lines */
void TreeSocket::SendXLines(TreeServer* Current)
{
        char data[MAXBUF];
        std::string buffer;
        std::string n = this->Instance->Config->ServerName;
        const char* sn = n.c_str();
        /* Yes, these arent too nice looking, but they get the job done */
        for (std::vector<ZLine*>::iterator i = Instance->XLines->zlines.begin(); i != Instance->XLines->zlines.end(); i++)
        {
                snprintf(data,MAXBUF,":%s ADDLINE Z %s %s %lu %lu :%s\r\n",sn,(*i)->ipaddr,(*i)->source,(unsigned long)(*i)->set_time,(unsigned long)(*i)->duration,(*i)->reason);
                buffer.append(data);
        }
        for (std::vector<QLine*>::iterator i = Instance->XLines->qlines.begin(); i != Instance->XLines->qlines.end(); i++)
        {
                snprintf(data,MAXBUF,":%s ADDLINE Q %s %s %lu %lu :%s\r\n",sn,(*i)->nick,(*i)->source,(unsigned long)(*i)->set_time,(unsigned long)(*i)->duration,(*i)->reason);
                buffer.append(data);
        }
        for (std::vector<GLine*>::iterator i = Instance->XLines->glines.begin(); i != Instance->XLines->glines.end(); i++)
        {
                snprintf(data,MAXBUF,":%s ADDLINE G %s@%s %s %lu %lu :%s\r\n",sn,(*i)->identmask,(*i)->hostmask,(*i)->source,(unsigned long)(*i)->set_time,(unsigned long)(*i)->duration,(*i)->reason);
                buffer.append(data);
        }
        for (std::vector<ELine*>::iterator i = Instance->XLines->elines.begin(); i != Instance->XLines->elines.end(); i++)
        {
                snprintf(data,MAXBUF,":%s ADDLINE E %s@%s %s %lu %lu :%s\r\n",sn,(*i)->identmask,(*i)->hostmask,(*i)->source,(unsigned long)(*i)->set_time,(unsigned long)(*i)->duration,(*i)->reason);
                buffer.append(data);
        }
        for (std::vector<ZLine*>::iterator i = Instance->XLines->pzlines.begin(); i != Instance->XLines->pzlines.end(); i++)
        {
                snprintf(data,MAXBUF,":%s ADDLINE Z %s %s %lu %lu :%s\r\n",sn,(*i)->ipaddr,(*i)->source,(unsigned long)(*i)->set_time,(unsigned long)(*i)->duration,(*i)->reason);
                buffer.append(data);
        }
        for (std::vector<QLine*>::iterator i = Instance->XLines->pqlines.begin(); i != Instance->XLines->pqlines.end(); i++)
        {
                snprintf(data,MAXBUF,":%s ADDLINE Q %s %s %lu %lu :%s\r\n",sn,(*i)->nick,(*i)->source,(unsigned long)(*i)->set_time,(unsigned long)(*i)->duration,(*i)->reason);
                buffer.append(data);
        }
        for (std::vector<GLine*>::iterator i = Instance->XLines->pglines.begin(); i != Instance->XLines->pglines.end(); i++)
        {
                snprintf(data,MAXBUF,":%s ADDLINE G %s@%s %s %lu %lu :%s\r\n",sn,(*i)->identmask,(*i)->hostmask,(*i)->source,(unsigned long)(*i)->set_time,(unsigned long)(*i)->duration,(*i)->reason);
                buffer.append(data);
        }
        for (std::vector<ELine*>::iterator i = Instance->XLines->pelines.begin(); i != Instance->XLines->pelines.end(); i++)
        {
                snprintf(data,MAXBUF,":%s ADDLINE E %s@%s %s %lu %lu :%s\r\n",sn,(*i)->identmask,(*i)->hostmask,(*i)->source,(unsigned long)(*i)->set_time,(unsigned long)(*i)->duration,(*i)->reason);
                buffer.append(data);
        }

        if (!buffer.empty())
                this->WriteLine(buffer);
}

/** Send channel modes and topics */
void TreeSocket::SendChannelModes(TreeServer* Current)
{
        char data[MAXBUF];
        std::deque<std::string> list;
        std::string n = this->Instance->Config->ServerName;
        const char* sn = n.c_str();
        Instance->Log(DEBUG,"Sending channels and modes, %d to send", this->Instance->chanlist->size());
        for (chan_hash::iterator c = this->Instance->chanlist->begin(); c != this->Instance->chanlist->end(); c++)
        {
                SendFJoins(Current, c->second);
                if (*c->second->topic)
                {
                        snprintf(data,MAXBUF,":%s FTOPIC %s %lu %s :%s",sn,c->second->name,(unsigned long)c->second->topicset,c->second->setby,c->second->topic);
                        this->WriteLine(data);
                }
                FOREACH_MOD_I(this->Instance,I_OnSyncChannel,OnSyncChannel(c->second,(Module*)Utils->Creator,(void*)this));
                list.clear();
                c->second->GetExtList(list);
                for (unsigned int j = 0; j < list.size(); j++)
                {
                        FOREACH_MOD_I(this->Instance,I_OnSyncChannelMetaData,OnSyncChannelMetaData(c->second,(Module*)Utils->Creator,(void*)this,list[j]));
                }
        }
}

/** send all users and their oper state/modes */
void TreeSocket::SendUsers(TreeServer* Current)
{
        char data[MAXBUF];
        std::deque<std::string> list;
        std::string dataline;
        for (user_hash::iterator u = this->Instance->clientlist->begin(); u != this->Instance->clientlist->end(); u++)
        {
                if (u->second->registered == REG_ALL)
                {
                        snprintf(data,MAXBUF,":%s NICK %lu %s %s %s %s +%s %s :%s",u->second->server,(unsigned long)u->second->age,u->second->nick,u->second->host,u->second->dhost,u->second->ident,u->second->FormatModes(),u->second->GetIPString(),u->second->fullname);
                        this->WriteLine(data);
                        if (*u->second->oper)
                        {
                                snprintf(data,MAXBUF,":%s OPERTYPE %s", u->second->nick, u->second->oper);
                                this->WriteLine(data);
                        }
                        if (*u->second->awaymsg)
                        {
                                snprintf(data,MAXBUF,":%s AWAY :%s", u->second->nick, u->second->awaymsg);
                                this->WriteLine(data);
                        }
                }
        }
        for (user_hash::iterator u = this->Instance->clientlist->begin(); u != this->Instance->clientlist->end(); u++)
        {
                FOREACH_MOD_I(this->Instance,I_OnSyncUser,OnSyncUser(u->second,(Module*)Utils->Creator,(void*)this));
                list.clear();
                u->second->GetExtList(list);
                for (unsigned int j = 0; j < list.size(); j++)
                {
                        FOREACH_MOD_I(this->Instance,I_OnSyncUserMetaData,OnSyncUserMetaData(u->second,(Module*)Utils->Creator,(void*)this,list[j]));
                }
        }
}

/** This function is called when we want to send a netburst to a local
 * server. There is a set order we must do this, because for example
 * users require their servers to exist, and channels require their
 * users to exist. You get the idea.
 */
void TreeSocket::DoBurst(TreeServer* s)
{
        std::string name = s->GetName();
        std::string burst = "BURST "+ConvToStr(Instance->Time(true));
        std::string endburst = "ENDBURST";
        this->Instance->SNO->WriteToSnoMask('l',"Bursting to \2%s\2 (Authentication: %s).", name.c_str(), this->GetTheirChallenge().empty() ? "plaintext password" : "SHA256-HMAC challenge-response");
        this->WriteLine(burst);
        /* send our version string */
        this->WriteLine(std::string(":")+this->Instance->Config->ServerName+" VERSION :"+this->Instance->GetVersionString());
        /* Send server tree */
        this->SendServers(Utils->TreeRoot,s,1);
        /* Send users and their oper status */
        this->SendUsers(s);
        /* Send everything else (channel modes, xlines etc) */
        this->SendChannelModes(s);
        this->SendXLines(s);
        FOREACH_MOD_I(this->Instance,I_OnSyncOtherMetaData,OnSyncOtherMetaData((Module*)Utils->Creator,(void*)this));
        this->WriteLine(endburst);
        this->Instance->SNO->WriteToSnoMask('l',"Finished bursting to \2"+name+"\2.");
}

/** This function is called when we receive data from a remote
 * server. We buffer the data in a std::string (it doesnt stay
 * there for long), reading using InspSocket::Read() which can
 * read up to 16 kilobytes in one operation.
 *
 * IF THIS FUNCTION RETURNS FALSE, THE CORE CLOSES AND DELETES
 * THE SOCKET OBJECT FOR US.
 */
bool TreeSocket::OnDataReady()
{
        char* data = this->Read();
        /* Check that the data read is a valid pointer and it has some content */
        if (data && *data)
        {
                this->in_buffer.append(data);
                /* While there is at least one new line in the buffer,
                 * do something useful (we hope!) with it.
                 */
                while (in_buffer.find("\n") != std::string::npos)
                {
                        std::string ret = in_buffer.substr(0,in_buffer.find("\n")-1);
                        in_buffer = in_buffer.substr(in_buffer.find("\n")+1,in_buffer.length()-in_buffer.find("\n"));
                        /* Use rfind here not find, as theres more
                         * chance of the \r being near the end of the
                         * string, not the start.
                         */
                        if (ret.find("\r") != std::string::npos)
                                ret = in_buffer.substr(0,in_buffer.find("\r")-1);
                        /* Process this one, abort if it
                         * didnt return true.
                         */
                        if (!this->ProcessLine(ret))
                        {
                                return false;
                        }
                }
                return true;
        }
        /* EAGAIN returns an empty but non-NULL string, so this
         * evaluates to TRUE for EAGAIN but to FALSE for EOF.
         */
        return (data && !*data);
}