sv_main.cpp

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/*
All original material Copyright (C) 2002-2025 UFO: Alien Invasion.
 
Original file from Quake 2 v3.21: quake2-2.31/server/sv_main.c
Copyright (C) 1997-2001 Id Software, Inc.
 
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
 
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 
See the GNU General Public License for more details.
 
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 
*/
 
#include "server.h"
#include "sv_log.h"
#include "../ports/system.h"
#include "../shared/scopedmutex.h"
#include "../shared/thread.h"

static cvar_t* rcon_password;
static cvar_t* sv_http_downloadserver;
static cvar_t* sv_enablemorale;
static cvar_t* sv_maxsoldiersperteam;
static cvar_t* sv_maxsoldiersperplayer;
static cvar_t* sv_hostname;
static cvar_t* sv_reconnect_limit;
static cvar_t* sv_timeout;          /* seconds without any message */
 
cvar_t* sv_maxclients = nullptr;
cvar_t* sv_dumpmapassembly;
cvar_t* sv_threads;
cvar_t* sv_rma;
cvar_t* sv_rmadisplaythemap;
cvar_t* sv_public;
cvar_t* sv_mapname;
 
memPool_t* sv_genericPool;
 
typedef struct leakyBucket_s {
    char node[64];
 
    int lastTime;
    signed char burst;
 
    long hash;
 
    struct leakyBucket_s* prev;
    struct leakyBucket_s* next;
} leakyBucket_t;
 
/* This is deliberately quite large to make it more of an effort to DoS */
#define MAX_BUCKETS         16384
#define MAX_HASHES          1024
 
static leakyBucket_t buckets[MAX_BUCKETS];
static leakyBucket_t* bucketHashes[MAX_HASHES];
static leakyBucket_t outboundLeakyBucket;
 
char* SV_GetConfigString (int index)
{
    if (!Com_CheckConfigStringIndex(index))
        Com_Error(ERR_FATAL, "Invalid config string index given: %i", index);
 
    return sv->configstrings[index];
}
 
int SV_GetConfigStringLength (int index)
{
    if (!Com_CheckConfigStringIndex(index))
        Com_Error(ERR_FATAL, "Invalid config string index given: %i", index);
 
    switch (index) {
    case CS_ENTITYSTRING:
        return MAX_TOKEN_CHARS * MAX_ENTITYSTRINGS;
    case CS_TILES:
        return MAX_TOKEN_CHARS * MAX_TILESTRINGS;
    case CS_POSITIONS:
        return MAX_TOKEN_CHARS * MAX_TILESTRINGS;
    case CS_MODELS:
        return MAX_TOKEN_CHARS * MAX_MODELS;
    case CS_PLAYERNAMES:
        return MAX_TOKEN_CHARS * MAX_CLIENTS;
    case CS_GENERAL:
        return MAX_TOKEN_CHARS * MAX_GENERAL;
    default:
        return MAX_TOKEN_CHARS;
    }
}
 
int SV_GetConfigStringInteger (int index)
{
    return atoi(SV_GetConfigString(index));
}
 
char* SV_SetConfigString (int index, ...)
{
    va_list ap;
    const char* value;
 
    if (!Com_CheckConfigStringIndex(index))
        Com_Error(ERR_FATAL, "Invalid config string index given: %i", index);
 
    va_start(ap, index);
 
    switch (index) {
    case CS_LIGHTMAP:
    case CS_MAPCHECKSUM:
    case CS_UFOCHECKSUM:
    case CS_OBJECTAMOUNT:
        value = va("%i", va_arg(ap, int));
        break;
    default:
        value = va_arg(ap, char*);
        break;
    }
 
    /* change the string in sv
     * there may be overflows in i==CS_TILES - but thats ok
     * see definition of configstrings and MAX_TILESTRINGS */
    if (index == CS_TILES || index == CS_POSITIONS)
        Q_strncpyz(sv->configstrings[index], value, MAX_TOKEN_CHARS * MAX_TILESTRINGS);
    else
        Q_strncpyz(sv->configstrings[index], value, sizeof(sv->configstrings[index]));
 
    va_end(ap);
 
    return sv->configstrings[index];
}

client_t* SV_GetNextClient (client_t* lastClient)
{
    client_t* endOfClients = &svs.clients[sv_maxclients->integer];
    client_t* client;
 
    if (!sv_maxclients->integer)
        return nullptr;
 
    if (!lastClient)
        return svs.clients;
    assert(lastClient >= svs.clients);
    assert(lastClient < endOfClients);
 
    client = lastClient;
 
    client++;
    if (client >= endOfClients)
        return nullptr;
    else
        return client;
}
 
client_t* SV_GetClient (int index)
{
    return &svs.clients[index];
}

void SV_DropClient (client_t* drop, const char* message)
{
    /* add the disconnect */
    dbuffer msg(2 + strlen(message));
    NET_WriteByte(&msg, svc_disconnect);
    NET_WriteString(&msg, message);
    NET_WriteMsg(drop->stream, msg);
    SV_BroadcastPrintf(PRINT_CHAT, "%s was dropped from the server - reason: %s\n", drop->name, message);
 
    if (drop->state == cs_spawned || drop->state == cs_spawning) {
        /* call the prog function for removing a client */
        /* this will remove the body, among other things */
        const ScopedMutex scopedMutex(svs.serverMutex);
        svs.ge->ClientDisconnect(*drop->player);
    }
 
    NET_StreamFinished(drop->stream);
    drop->stream = nullptr;
 
    drop->player->setInUse(false);
    SV_SetClientState(drop, cs_free);
    drop->name[0] = 0;
 
    if (svs.abandon) {
        int count = 0;
        client_t* cl = nullptr;
        while ((cl = SV_GetNextClient(cl)) != nullptr)
            if (cl->state >= cs_connected)
                count++;
        if (count == 0)
            svs.killserver = true;
    }
}
 
/*
==============================================================================
CONNECTIONLESS COMMANDS
==============================================================================
*/

static leakyBucket_t* SVC_BucketForAddress (struct net_stream& address, int burst, int period)
{
    char node[64];
    NET_StreamPeerToName(&address, node, sizeof(node), false);
 
    const long hash = Com_HashKey(node, MAX_HASHES);
    const int now = Sys_Milliseconds();
 
    for (leakyBucket_t* bucket = bucketHashes[hash]; bucket; bucket = bucket->next) {
        if (!Q_streq(bucket->node, node))
            continue;
 
        return bucket;
    }
 
    for (int i = 0; i < MAX_BUCKETS; i++) {
        leakyBucket_t* bucket = &buckets[i];
        const int interval = now - bucket->lastTime;
 
        /* Reclaim expired buckets */
        if (bucket->lastTime > 0 && (interval > (burst * period) || interval < 0)) {
            if (bucket->prev != nullptr) {
                bucket->prev->next = bucket->next;
            } else {
                bucketHashes[bucket->hash] = bucket->next;
            }
 
            if (bucket->next != nullptr) {
                bucket->next->prev = bucket->prev;
            }
 
            OBJZERO(*bucket);
        }
 
        if (Q_strnull(bucket->node)) {
            Q_strncpyz(bucket->node, node, sizeof(bucket->node));
            bucket->lastTime = now;
            bucket->burst = 0;
            bucket->hash = hash;
 
            /* Add to the head of the relevant hash chain */
            bucket->next = bucketHashes[hash];
            if (bucketHashes[hash] != nullptr) {
                bucketHashes[hash]->prev = bucket;
            }
 
            bucket->prev = nullptr;
            bucketHashes[hash] = bucket;
 
            return bucket;
        }
    }
 
    /* Couldn't allocate a bucket for this address */
    return nullptr;
}
 
static bool SVC_RateLimit (leakyBucket_t* bucket, int burst = 10, int period = 100)
{
    if (bucket == nullptr)
        return true;
 
    const int now = Sys_Milliseconds();
    const int interval = now - bucket->lastTime;
    const int expired = interval / period;
    const int expiredRemainder = interval % period;
 
    if (expired > bucket->burst) {
        bucket->burst = 0;
        bucket->lastTime = now;
    } else {
        bucket->burst -= expired;
        bucket->lastTime = now - expiredRemainder;
    }
 
    if (bucket->burst < burst) {
        bucket->burst++;
        return false;
    }
 
    return true;
}

static bool SVC_RateLimitAddress (struct net_stream& from, int burst = 10, int period = 1000)
{
    leakyBucket_t* bucket = SVC_BucketForAddress(from, burst, period);
    return SVC_RateLimit(bucket, burst, period);
}

static void SVC_TeamInfo (struct net_stream* s)
{
    if (SVC_RateLimitAddress(*s)) {
        Com_DPrintf(DEBUG_SERVER, "SVC_TeamInfo: rate limit from %s exceeded, dropping request\n", NET_StreamToString(s));
        return;
    }
 
    /* Allow getinfo to be DoSed relatively easily, but prevent excess outbound bandwidth usage when being flooded inbound */
    if (SVC_RateLimit(&outboundLeakyBucket)) {
        Com_DPrintf(DEBUG_SERVER, "SVC_TeamInfo: rate limit exceeded, dropping request\n");
        return;
    }
 
    char infoGlobal[MAX_INFO_STRING] = "";
    Info_SetValueForKey(infoGlobal, sizeof(infoGlobal), "sv_teamplay", Cvar_GetString("sv_teamplay"));
    Info_SetValueForKey(infoGlobal, sizeof(infoGlobal), "sv_maxteams", Cvar_GetString("sv_maxteams"));
    Info_SetValueForKey(infoGlobal, sizeof(infoGlobal), "sv_maxplayersperteam", Cvar_GetString("sv_maxplayersperteam"));
 
    dbuffer msg;
    NET_WriteByte(&msg, svc_oob);
    NET_WriteRawString(&msg, "teaminfo\n");
    NET_WriteString(&msg, infoGlobal);
 
    client_t* cl = nullptr;
    while ((cl = SV_GetNextClient(cl)) != nullptr) {
        if (cl->state < cs_connected)
            continue;
        char infoPlayer[MAX_INFO_STRING] = "";
        /* show players that already have a team with their teamnum */
        int teamId = svs.ge->ClientGetTeamNum(*cl->player);
        if (!teamId)
            teamId = TEAM_NO_ACTIVE;
        Info_SetValueForKeyAsInteger(infoPlayer, sizeof(infoPlayer), "cl_team", teamId);
        Info_SetValueForKeyAsInteger(infoPlayer, sizeof(infoPlayer), "cl_ready", svs.ge->ClientIsReady(cl->player));
        Info_SetValueForKey(infoPlayer, sizeof(infoPlayer), "cl_name", cl->name);
        NET_WriteString(&msg, infoPlayer);
    }
 
    NET_WriteByte(&msg, 0);
 
    NET_WriteMsg(s, msg);
}

static void SVC_Status (struct net_stream* s)
{
    if (SVC_RateLimitAddress(*s)) {
        Com_DPrintf(DEBUG_SERVER, "SVC_Status: rate limit from %s exceeded, dropping request\n", NET_StreamToString(s));
        return;
    }
 
    /* Allow getstatus to be DoSed relatively easily, but prevent excess outbound bandwidth usage when being flooded inbound */
    if (SVC_RateLimit(&outboundLeakyBucket, 10, 100)) {
        Com_DPrintf(DEBUG_SERVER, "SVC_Status: rate limit exceeded, dropping request\n");
        return;
    }
 
    dbuffer msg;
    NET_WriteByte(&msg, svc_oob);
    NET_WriteRawString(&msg, SV_CMD_PRINT "\n");
    char info[MAX_INFO_STRING];
    NET_WriteRawString(&msg, Cvar_Serverinfo(info, sizeof(info)));
    NET_WriteRawString(&msg, "\n");
 
    client_t* cl = nullptr;
    while ((cl = SV_GetNextClient(cl)) != nullptr) {
        if (cl->state <= cs_free)
            continue;
 
        char player[1024];
        Com_sprintf(player, sizeof(player), "%i \"%s\"\n", svs.ge->ClientGetTeamNum(*cl->player), cl->name);
        NET_WriteRawString(&msg, player);
    }
 
    NET_WriteMsg(s, msg);
}

static void SVC_Info (struct net_stream* s)
{
    if (SVC_RateLimitAddress(*s)) {
        Com_DPrintf(DEBUG_SERVER, "SVC_Info: rate limit from %s exceeded, dropping request\n", NET_StreamToString(s));
        return;
    }
 
    /* Allow getinfo to be DoSed relatively easily, but prevent excess outbound bandwidth usage when being flooded inbound */
    if (SVC_RateLimit(&outboundLeakyBucket)) {
        Com_DPrintf(DEBUG_SERVER, "SVC_Info: rate limit exceeded, dropping request\n");
        return;
    }
 
    if (sv_maxclients->integer == 1) {
        Com_DPrintf(DEBUG_SERVER, "Ignore info string in singleplayer mode\n");
        return; /* ignore in single player */
    }
 
    const int version = atoi(Cmd_Argv(1));
    if (version != PROTOCOL_VERSION) {
        char string[MAX_VAR];
        Com_sprintf(string, sizeof(string), "%s: wrong version (client: %i, host: %i)\n", sv_hostname->string, version, PROTOCOL_VERSION);
        NET_OOB_Printf(s, SV_CMD_PRINT "\n%s", string);
        return;
    }
 
    int count = 0;
 
    client_t* cl = nullptr;
    while ((cl = SV_GetNextClient(cl)) != nullptr)
        if (cl->state >= cs_spawning)
            count++;
 
    char infostring[MAX_INFO_STRING];
    infostring[0] = '\0';
    Info_SetValueForKey(infostring, sizeof(infostring), "sv_protocol", DOUBLEQUOTE(PROTOCOL_VERSION));
    Info_SetValueForKey(infostring, sizeof(infostring), "sv_hostname", sv_hostname->string);
    Info_SetValueForKey(infostring, sizeof(infostring), "sv_dedicated", sv_dedicated->string);
    Info_SetValueForKey(infostring, sizeof(infostring), "sv_gametype", sv_gametype->string);
    Info_SetValueForKey(infostring, sizeof(infostring), "sv_mapname", sv->name);
    Info_SetValueForKeyAsInteger(infostring, sizeof(infostring), "clients", count);
    Info_SetValueForKey(infostring, sizeof(infostring), "sv_maxclients", sv_maxclients->string);
    Info_SetValueForKey(infostring, sizeof(infostring), "sv_version", UFO_VERSION);
    NET_OOB_Printf(s, SV_CMD_INFO "\n%s", infostring);
}
 

static void SVC_DirectConnect (struct net_stream* stream)
{
    Com_DPrintf(DEBUG_SERVER, "SVC_DirectConnect()\n");
 
    if (sv->started || sv->spawned) {
        Com_Printf("rejected connect because match is already running\n");
        NET_OOB_Printf(stream, SV_CMD_PRINT "\n" REJ_GAME_ALREADY_STARTED "\n");
        return;
    }
 
    char buf[256];
    const char* peername = NET_StreamPeerToName(stream, buf, sizeof(buf), false);
 
    const int version = atoi(Cmd_Argv(1));
    if (version != PROTOCOL_VERSION) {
        Com_Printf("rejected connect from version %i - %s\n", version, peername);
        NET_OOB_Printf(stream, SV_CMD_PRINT "\n" REJ_SERVER_VERSION_MISMATCH "\n");
        return;
    }
 
    char userinfo[MAX_INFO_STRING];
    Q_strncpyz(userinfo, Cmd_Argv(2), sizeof(userinfo));
 
    if (Q_strnull(userinfo)) {  /* catch empty userinfo */
        Com_Printf("Empty userinfo from %s\n", peername);
        NET_OOB_Printf(stream, SV_CMD_PRINT "\n" REJ_CONNECTION_REFUSED "\n");
        return;
    }
 
    if (strchr(userinfo, '\xFF')) {  /* catch end of message in string exploit */
        Com_Printf("Illegal userinfo contained xFF from %s\n", peername);
        NET_OOB_Printf(stream, SV_CMD_PRINT "\n" REJ_CONNECTION_REFUSED "\n");
        return;
    }
 
    if (strlen(Info_ValueForKey(userinfo, "ip"))) {  /* catch spoofed ips  */
        Com_Printf("Illegal userinfo contained ip from %s\n", peername);
        NET_OOB_Printf(stream, SV_CMD_PRINT "\n" REJ_CONNECTION_REFUSED "\n");
        return;
    }
 
    /* force the IP key/value pair so the game can filter based on ip */
    Info_SetValueForKey(userinfo, sizeof(userinfo), "ip", peername);
 
    /* find a client slot */
    client_t* cl = nullptr;
    while ((cl = SV_GetNextClient(cl)) != nullptr)
        if (cl->state == cs_free)
            break;
    if (cl == nullptr) {
        NET_OOB_Printf(stream, SV_CMD_PRINT "\n" REJ_SERVER_FULL "\n");
        Com_Printf("Rejected a connection - server is full.\n");
        return;
    }
 
    /* build a new connection - accept the new client
     * this is the only place a client_t is ever initialized */
    OBJZERO(*cl);
    const int playernum = cl - SV_GetClient(0);
    SrvPlayer* player = PLAYER_NUM(playernum);
    cl->player = player;
    cl->player->setNum(playernum);
 
    bool connected;
    {
        const ScopedMutex scopedMutex(svs.serverMutex);
        connected = svs.ge->ClientConnect(player, userinfo, sizeof(userinfo));
    }
 
    /* get the game a chance to reject this connection or modify the userinfo */
    if (!connected) {
        const char* rejmsg = Info_ValueForKey(userinfo, "rejmsg");
        if (rejmsg[0] != '\0') {
            NET_OOB_Printf(stream, SV_CMD_PRINT "\n%s\n" REJ_CONNECTION_REFUSED "\n", rejmsg);
            Com_Printf("Game rejected a connection from %s. Reason: %s\n", peername, rejmsg);
        } else {
            NET_OOB_Printf(stream, SV_CMD_PRINT "\n" REJ_CONNECTION_REFUSED "\n");
            Com_Printf("Game rejected a connection from %s.\n", peername);
        }
        return;
    }
 
    /* new player */
    cl->player->setInUse(true);
    cl->lastmessage = svs.realtime;
 
    /* parse some info from the info strings */
    Q_strncpyz(cl->userinfo, userinfo, sizeof(cl->userinfo));
    SV_UserinfoChanged(cl);
 
    /* send the connect packet to the client */
    if (sv_http_downloadserver->string[0])
        NET_OOB_Printf(stream, CL_CMD_CLIENT_CONNECT " dlserver=%s", sv_http_downloadserver->string);
    else
        NET_OOB_Printf(stream, CL_CMD_CLIENT_CONNECT);
 
    SV_SetClientState(cl, cs_connected);
 
    Q_strncpyz(cl->peername, peername, sizeof(cl->peername));
    cl->stream = stream;
    NET_StreamSetData(stream, cl);
}

static inline bool Rcon_Validate (const char* password)
{
    /* no rcon access */
    if (Q_strnull(rcon_password->string))
        return false;
 
    /* password not valid */
    if (!Q_streq(password, rcon_password->string))
        return false;
 
    return true;
}

static void SVC_RemoteCommand (struct net_stream* stream)
{
    char buf[64];
    const char* peername = NET_StreamPeerToName(stream, buf, sizeof(buf), false);
 
    /* Prevent using rcon as an amplifier and make dictionary attacks impractical */
    if (SVC_RateLimitAddress(*stream)) {
        Com_DPrintf(DEBUG_SERVER, "SVC_RemoteCommand: rate limit from %s exceeded, dropping request\n", peername);
        return;
    }
 
    const bool valid = Rcon_Validate(Cmd_Argv(1));
    if (!valid) {
        static leakyBucket_t bucket;
        /* Make DoS via rcon impractical */
        if (SVC_RateLimit(&bucket, 10, 1000)) {
            Com_DPrintf(DEBUG_SERVER, "SVC_RemoteCommand: rate limit exceeded, dropping request\n");
            return;
        }
 
        Com_Printf("Bad rcon from %s with password: '%s'\n", peername, Cmd_Argv(1));
    } else {
        Com_Printf("Rcon from %s\n", peername);
    }
 
    static char sv_outputbuf[1024];
    Com_BeginRedirect(stream, sv_outputbuf, sizeof(sv_outputbuf));
 
    if (!valid) {
        /* inform the client */
        Com_Printf(BAD_RCON_PASSWORD);
    } else {
        char remaining[1024] = "";
        int i;
 
        /* execute the rcon commands */
        for (i = 2; i < Cmd_Argc(); i++) {
            Q_strcat(remaining, sizeof(remaining), "%s ", Cmd_Argv(i));
        }
 
        /* execute the string */
        Cmd_ExecuteString("%s", remaining);
    }
 
    Com_EndRedirect();
}

static void SV_ConnectionlessPacket (struct net_stream* stream, dbuffer* msg)
{
    char s[512];
 
    NET_ReadStringLine(msg, s, sizeof(s));
    Cmd_TokenizeString(s, false, false);
 
    const char* c = Cmd_Argv(0);
    Com_DPrintf(DEBUG_SERVER, "Packet : %s\n", c);
 
    if (Q_streq(c, SV_CMD_TEAMINFO)) {
        SVC_TeamInfo(stream);
    } else if (Q_streq(c, SV_CMD_INFO)) {
        SVC_Info(stream);
    } else if (Q_streq(c, SV_CMD_STATUS)) {
        SVC_Status(stream);
    } else if (Q_streq(c, SV_CMD_CONNECT)) {
        SVC_DirectConnect(stream);
    } else if (Q_streq(c, SV_CMD_RCON)) {
        SVC_RemoteCommand(stream);
    } else {
        char buf[256];
        Com_Printf("Bad connectionless packet from %s:\n%s\n", NET_StreamPeerToName(stream, buf, sizeof(buf), true), s);
    }
}

void SV_ReadPacket (struct net_stream* s)
{
    client_t* cl = static_cast<client_t* >(NET_StreamGetData(s));
    dbuffer* msg;
 
    while ((msg = NET_ReadMsg(s))) {
        const int cmd = NET_ReadByte(msg);
 
        if (cmd == clc_oob)
            SV_ConnectionlessPacket(s, msg);
        else if (cl)
            SV_ExecuteClientMessage(cl, cmd, msg);
        else {
            NET_StreamFree(s);
            s = nullptr;
        }
 
        delete msg;
    }
}
 
#define HEARTBEAT_SECONDS   30
 
static SDL_Thread* masterServerHeartBeatThread;

static int Master_HeartbeatThread (void*  data)
{
    char url[512];
    Com_sprintf(url, sizeof(url), "%s/ufo/masterserver.php?heartbeat&port=%s", masterserver_url->string, port->string);
 
    /* send to master */
    Com_Printf("sending heartbeat\n");
    HTTP_GetURL(url, nullptr);
 
    masterServerHeartBeatThread = nullptr;
    return 0;
}

static void Master_Heartbeat (void)
{
    if (!sv_dedicated || !sv_dedicated->integer)
        return;     /* only dedicated servers send heartbeats */
 
    if (!sv_public || !sv_public->integer)
        return;     /* a private dedicated game */
 
    /* check for time wraparound */
    if (svs.lastHeartbeat > svs.realtime)
        svs.lastHeartbeat = svs.realtime;
 
    if (svs.realtime - svs.lastHeartbeat < HEARTBEAT_SECONDS * 1000)
        return;                 /* not time to send yet */
 
    svs.lastHeartbeat = svs.realtime;
 
    if (masterServerHeartBeatThread != nullptr)
        SDL_WaitThread(masterServerHeartBeatThread, nullptr);
 
    masterServerHeartBeatThread = Com_CreateThread(Master_HeartbeatThread, "HeartbeatThread");
}

static void SV_CheckSpawnSoldiers (void)
{
    /* already started? */
    if (sv->spawned)
        return;
 
    client_t* cl = nullptr;
    while ((cl = SV_GetNextClient(cl)) != nullptr) {
        /* all players must be connected and all of them must have set
         * the ready flag */
        if (cl->state != cs_began || !cl->player->isReady())
            return;
    }
 
    sv->spawned = true;
 
    cl = nullptr;
    while ((cl = SV_GetNextClient(cl)) != nullptr)
        if (cl->state != cs_free)
            SV_ClientCommand(cl, CL_SPAWNSOLDIERS "\n");
}
 
static void SV_CheckStartMatch (void)
{
    client_t* cl;
 
    if (!sv->spawned || sv->started)
        return;
 
    if (sv_maxclients->integer > 1) {
        cl = nullptr;
        while ((cl = SV_GetNextClient(cl)) != nullptr) {
            /* all players must have their actors spawned */
            if (cl->state != cs_spawned)
                return;
        }
    } else if (SV_GetClient(0)->state != cs_spawned) {
        /* in single player mode we must have received the 'spawnsoldiers' */
        return;
    }
 
    sv->started = true;
 
    cl = nullptr;
    while ((cl = SV_GetNextClient(cl)) != nullptr)
        if (cl->state != cs_free)
            SV_ClientCommand(cl, CL_STARTMATCH "\n");
}
 
#define PING_SECONDS    5
 
static void SV_PingPlayers (void)
{
    /* check for time wraparound */
    if (svs.lastPing > svs.realtime)
        svs.lastPing = svs.realtime;
 
    if (svs.realtime - svs.lastPing < PING_SECONDS * 1000)
        return;                 /* not time to send yet */
 
    svs.lastPing = svs.realtime;
    client_t* cl = nullptr;
    while ((cl = SV_GetNextClient(cl)) != nullptr) {
        if (cl->state == cs_free)
            continue;
        dbuffer msg(1);
        NET_WriteByte(&msg, svc_ping);
        NET_WriteMsg(cl->stream, msg);
    }
}
 
static void SV_CheckTimeouts (void)
{
    const int droppoint = svs.realtime - 1000 * sv_timeout->integer;
 
    if (sv_maxclients->integer == 1)
        return;
 
    client_t* cl = nullptr;
    while ((cl = SV_GetNextClient(cl)) != nullptr) {
        if (cl->state == cs_free)
            continue;
 
        /* might be invalid across a mapchange */
        if (cl->lastmessage > svs.realtime)
            cl->lastmessage = svs.realtime;
 
        if (cl->lastmessage > 0 && cl->lastmessage < droppoint)
            SV_DropClient(cl, "timed out");
    }
}

void SV_Frame (int now, void* data)
{
    Com_ReadFromPipe();
 
    /* change the gametype even if no server is running (e.g. the first time) */
    if (sv_dedicated->integer && sv_gametype->modified) {
        Com_SetGameType();
        sv_gametype->modified = false;
    }
 
    if (sv_dedicated->integer) {
        const char* s;
        do {
            s = Sys_ConsoleInput();
            if (s)
                Cbuf_AddText("%s\n", s);
        } while (s);
    }
 
    /* if server is not active, do nothing */
    if (!svs.initialized) {
#ifdef DEDICATED_ONLY
        Com_Printf("Starting next map from the mapcycle\n");
        SV_NextMapcycle();
#endif
        return;
    }
 
    svs.realtime = now;
 
    /* if time is about to hit the 32nd bit, kick all clients
     * and clear sv.time, rather
     * than checking for negative time wraparound everywhere.
     * 2giga-milliseconds = 23 days, so it won't be too often */
    if (svs.realtime > 0x70000000) {
        SV_Map(true, sv->name, sv->assembly);
        return;
    }
 
    /* keep the random time dependent */
    rand();
 
    SV_CheckSpawnSoldiers();
    SV_CheckStartMatch();
    SV_CheckTimeouts();
 
    if (!sv_threads->integer)
        SV_RunGameFrame();
    else
        /* signal the game frame thread to wake up */
        SDL_CondSignal(svs.gameFrameCond);
    SV_LogHandleOutput();
 
    /* next map in the cycle */
    if (sv->endgame && sv_maxclients->integer > 1)
        SV_NextMapcycle();
 
    /* send a heartbeat to the master if needed */
    Master_Heartbeat();
    SV_PingPlayers();
 
    /* server is empty - so shutdown */
    if (svs.abandon && svs.killserver)
        SV_Shutdown("Server disconnected.", false);
}

static void Master_Shutdown (void)
{
    if (!sv_dedicated || !sv_dedicated->integer)
        return;                 /* only dedicated servers send heartbeats */
 
    if (!sv_public || !sv_public->integer)
        return;                 /* a private dedicated game */
 
    /* send to master */
    HTTP_GetURL(va("%s/ufo/masterserver.php?shutdown&port=%s", masterserver_url->string, port->string), nullptr);
}

void SV_UserinfoChanged (client_t* cl)
{
    /* call prog code to allow overrides */
    {
        const ScopedMutex scopedMutex(svs.serverMutex);
        svs.ge->ClientUserinfoChanged(*cl->player, cl->userinfo);
    }
 
    /* name of the player */
    Q_strncpyz(cl->name, Info_ValueForKey(cl->userinfo, "cl_name"), sizeof(cl->name));
    /* mask off high bit */
    for (int i = 0; i < sizeof(cl->name); i++)
        cl->name[i] &= 127;
 
    /* msg command */
    cl->messagelevel = Info_IntegerForKey(cl->userinfo, "cl_msg");
 
    Com_DPrintf(DEBUG_SERVER, "SV_UserinfoChanged: Changed userinfo for player %s\n", cl->name);
}
 
static bool SV_CheckMaxSoldiersPerPlayer (cvar_t* cvar)
{
    const int max = MAX_ACTIVETEAM;
    return Cvar_AssertValue(cvar, 1, max, true);
}
 
mapData_t* SV_GetMapData (void)
{
    return &sv->mapData;
}
 
mapTiles_t* SV_GetMapTiles (void)
{
    return &sv->mapTiles;
}

void SV_Init (void)
{
    Com_Printf("\n------ server initialization -------\n");
 
    sv_genericPool = Mem_CreatePool("Server: Generic");
 
    OBJZERO(svs);
 
    sv = Mem_PoolAllocType(serverInstanceGame_t, sv_genericPool);
 
    SV_InitOperatorCommands();
 
    rcon_password = Cvar_Get("rcon_password", "", CVAR_ARCHIVE);
    Cvar_Get("sv_cheats", "0", CVAR_SERVERINFO | CVAR_LATCH);
    Cvar_Get("sv_protocol", DOUBLEQUOTE(PROTOCOL_VERSION), CVAR_SERVERINFO | CVAR_NOSET);
    /* this cvar will become a latched cvar when you start the server */
    sv_maxclients = Cvar_Get("sv_maxclients", "1", CVAR_SERVERINFO, "Max. connected clients");
    sv_hostname = Cvar_Get("sv_hostname", "noname", CVAR_SERVERINFO | CVAR_ARCHIVE, "The name of the server that is displayed in the serverlist");
    sv_http_downloadserver = Cvar_Get("sv_http_downloadserver", "", CVAR_ARCHIVE, "URL to a location where clients can download game content over HTTP");
    sv_enablemorale = Cvar_Get("sv_enablemorale", "1", CVAR_ARCHIVE | CVAR_SERVERINFO | CVAR_LATCH, "Enable morale changes in multiplayer");
    sv_maxsoldiersperteam = Cvar_Get("sv_maxsoldiersperteam", "4", CVAR_ARCHIVE | CVAR_SERVERINFO, "Max. amount of soldiers per team (see sv_maxsoldiersperplayer and sv_teamplay)");
    sv_maxsoldiersperplayer = Cvar_Get("sv_maxsoldiersperplayer", DOUBLEQUOTE(MAX_ACTIVETEAM), CVAR_ARCHIVE | CVAR_SERVERINFO, "Max. amount of soldiers each player can control (see maxsoldiers and sv_teamplay)");
    Cvar_SetCheckFunction("sv_maxsoldiersperplayer", SV_CheckMaxSoldiersPerPlayer);
 
    sv_dumpmapassembly = Cvar_Get("sv_dumpmapassembly", "0", CVAR_ARCHIVE, "Dump map assembly information to game console");
 
    sv_threads = Cvar_Get("sv_threads", "1", CVAR_LATCH | CVAR_ARCHIVE, "Run the server threaded");
    sv_rma = Cvar_Get("sv_rma", "2", 0, "1 = old algorithm, 2 = new algorithm");
    sv_rmadisplaythemap = Cvar_Get("sv_rmadisplaythemap", "0", 0, "Activate rma problem output");
    sv_public = Cvar_Get("sv_public", "1", 0, "Should heartbeats be send to the masterserver");
    sv_reconnect_limit = Cvar_Get("sv_reconnect_limit", "3", CVAR_ARCHIVE, "Minimum seconds between connect messages");
    sv_timeout = Cvar_Get("sv_timeout", "200", CVAR_ARCHIVE, "Seconds until a client times out");
 
    SV_MapcycleInit();
    SV_LogInit();
}

static void SV_FinalMessage (const char* message, bool reconnect)
{
    client_t* cl;
    dbuffer msg(2 + strlen(message));
 
    if (reconnect)
        NET_WriteByte(&msg, svc_reconnect);
    else
        NET_WriteByte(&msg, svc_disconnect);
    NET_WriteString(&msg, message);
 
    cl = nullptr;
    while ((cl = SV_GetNextClient(cl)) != nullptr)
        if (cl->state >= cs_connected) {
            NET_WriteConstMsg(cl->stream, msg);
            NET_StreamFinished(cl->stream);
            cl->stream = nullptr;
        }
 
    /* make sure, that this is send */
    NET_Wait(0);
}

void SV_Clear (void)
{
    SV_MapcycleClear();
    SV_LogShutdown();
}

void SV_Shutdown (const char* finalmsg, bool reconnect)
{
    if (!svs.initialized)
        return;
 
    if (svs.clients)
        SV_FinalMessage(finalmsg, reconnect);
 
    Com_Printf("Shutdown server: %s\n", finalmsg);
 
    Master_Shutdown();
    SV_ShutdownGameProgs();
 
    NET_DatagramSocketClose(svs.netDatagramSocket);
    SV_Stop();
 
    for (int i = 0; i < sv->numSVModels; i++) {
        sv_model_t* model = &sv->svModels[i];
        Mem_Free(model->name);
    }
 
    /* free current level */
    OBJZERO(*sv);
 
    /* free server static data */
    Mem_Free(svs.clients);
 
    SDL_DestroyMutex(svs.serverMutex);
 
    OBJZERO(svs);
 
    /* maybe we shut down before we init - e.g. in case of an error */
    if (sv_maxclients)
        sv_maxclients->flags &= ~CVAR_LATCH;
 
    if (sv_mapname)
        sv_mapname->flags &= ~CVAR_NOSET;
}

void SV_ShutdownWhenEmpty (void)
{
    svs.abandon = true;
    /* pretend server is already dead, otherwise clients may try and reconnect */
    Com_SetServerState(ss_dead);
}

int SV_CountPlayers (void)
{
    int count = 0;
    client_t* cl;
 
    if (!svs.initialized)
        return 0;
 
    cl = nullptr;
    while ((cl = SV_GetNextClient(cl)) != nullptr) {
        if (cl->state != cs_spawned)
            continue;
 
        count++;
    }
 
    return count;
}