/*
* @brief A connection request that did not come from the master.
*/
static void Svc_Connect(void) {
char user_info[MAX_USER_INFO_STRING];
sv_client_t *cl, *client;
int32_t i;
Com_Debug("Svc_Connect()\n");
net_addr_t *addr = &net_from;
const int32_t version = strtol(Cmd_Argv(1), NULL, 0);
// resolve protocol
if (version != PROTOCOL) {
Netchan_OutOfBandPrint(NS_UDP_SERVER, addr, "print\nServer is version %d.\n", PROTOCOL);
return;
}
const uint8_t qport = strtoul(Cmd_Argv(2), NULL, 0);
const uint32_t challenge = strtoul(Cmd_Argv(3), NULL, 0);
// copy user_info, leave room for ip stuffing
g_strlcpy(user_info, Cmd_Argv(4), sizeof(user_info) - 25);
if (*user_info == '\0') { // catch empty user_info
Com_Print("Empty user_info from %s\n", Net_NetaddrToString(addr));
Netchan_OutOfBandPrint(NS_UDP_SERVER, addr, "print\nConnection refused\n");
return;
}
if (strchr(user_info, '\xFF')) { // catch end of message in string exploit
Com_Print("Illegal user_info contained xFF from %s\n", Net_NetaddrToString(addr));
Netchan_OutOfBandPrint(NS_UDP_SERVER, addr, "print\nConnection refused\n");
return;
}
if (strlen(GetUserInfo(user_info, "ip"))) { // catch spoofed ips
Com_Print("Illegal user_info contained ip from %s\n", Net_NetaddrToString(addr));
Netchan_OutOfBandPrint(NS_UDP_SERVER, addr, "print\nConnection refused\n");
return;
}
if (!ValidateUserInfo(user_info)) { // catch otherwise invalid user_info
Com_Print("Invalid user_info from %s\n", Net_NetaddrToString(addr));
Netchan_OutOfBandPrint(NS_UDP_SERVER, addr, "print\nConnection refused\n");
return;
}
// force the ip so the game can filter on it
SetUserInfo(user_info, "ip", Net_NetaddrToString(addr));
// enforce a valid challenge to avoid denial of service attack
for (i = 0; i < MAX_CHALLENGES; i++) {
if (Net_CompareClientNetaddr(addr, &svs.challenges[i].addr)) {
if (challenge == svs.challenges[i].challenge) {
svs.challenges[i].challenge = 0;
break; // good
}
Netchan_OutOfBandPrint(NS_UDP_SERVER, addr, "print\nBad challenge\n");
return;
}
}
if (i == MAX_CHALLENGES) {
Netchan_OutOfBandPrint(NS_UDP_SERVER, addr, "print\nNo challenge for address\n");
return;
}
// resolve the client slot
client = NULL;
// first check for an ungraceful reconnect (client crashed, perhaps)
for (i = 0, cl = svs.clients; i < sv_max_clients->integer; i++, cl++) {
const net_chan_t *ch = &cl->net_chan;
if (cl->state == SV_CLIENT_FREE) // not in use, not interested
continue;
// the base address and either the qport or real port must match
if (Net_CompareClientNetaddr(addr, &ch->remote_address)) {
if (addr->port == ch->remote_address.port || qport == ch->qport) {
client = cl;
break;
}
}
}
// otherwise, treat as a fresh connect to a new slot
if (!client) {
for (i = 0, cl = svs.clients; i < sv_max_clients->integer; i++, cl++) {
if (cl->state == SV_CLIENT_FREE && !cl->edict->ai) { // we have a free one
client = cl;
break;
}
}
}
// no soup for you, next!!
if (!client) {
Netchan_OutOfBandPrint(NS_UDP_SERVER, addr, "print\nServer is full\n");
Com_Debug("Rejected a connection\n");
return;
}
// give the game a chance to reject this connection or modify the user_info
if (!(svs.game->ClientConnect(client->edict, user_info))) {
const char *rejmsg = GetUserInfo(user_info, "rejmsg");
if (strlen(rejmsg)) {
Netchan_OutOfBandPrint(NS_UDP_SERVER, addr, "print\n%s\nConnection refused\n", rejmsg);
} else {
Netchan_OutOfBandPrint(NS_UDP_SERVER, addr, "print\nConnection refused\n");
}
Com_Debug("Game rejected a connection\n");
return;
}
// parse some info from the info strings
g_strlcpy(client->user_info, user_info, sizeof(client->user_info));
Sv_UserInfoChanged(client);
// send the connect packet to the client
Netchan_OutOfBandPrint(NS_UDP_SERVER, addr, "client_connect %s", sv_download_url->string);
Netchan_Setup(NS_UDP_SERVER, &client->net_chan, addr, qport);
Mem_InitBuffer(&client->datagram.buffer, client->datagram.data, sizeof(client->datagram.data));
client->datagram.buffer.allow_overflow = true;
client->last_message = svs.real_time; // don't timeout
client->state = SV_CLIENT_CONNECTED;
}
/*
* Sv_ParseClientMessage
*
* The current net_message is parsed for the given client.
*/
void Sv_ParseClientMessage(sv_client_t *cl) {
user_cmd_t null_cmd, oldest_cmd, old_cmd, new_cmd;
int net_drop;
int strings_issued;
int moves_issued;
int last_frame;
int c;
char *s;
sv_client = cl;
sv_player = sv_client->edict;
// allow a finite number of moves and strings
moves_issued = strings_issued = 0;
while (true) {
if (net_message.read > net_message.size) {
Com_Warn("Sv_ParseClientMessage: Bad read from %s\n",
Sv_NetaddrToString(sv_client));
Sv_DropClient(cl);
return;
}
c = Msg_ReadByte(&net_message);
if (c == -1)
break;
switch (c) {
case CL_CMD_USER_INFO:
strncpy(cl->user_info, Msg_ReadString(&net_message), sizeof(cl->user_info) - 1);
Sv_UserInfoChanged(cl);
break;
case CL_CMD_MOVE:
if (++moves_issued > CMD_MAX_MOVES) {
return; // someone is trying to cheat
}
last_frame = Msg_ReadLong(&net_message);
if (last_frame != cl->last_frame) {
cl->last_frame = last_frame;
if (cl->last_frame > -1) {
cl->frame_latency[cl->last_frame & (CLIENT_LATENCY_COUNTS
- 1)] = svs.real_time - cl->frames[cl->last_frame
& UPDATE_MASK].sent_time;
}
}
memset(&null_cmd, 0, sizeof(null_cmd));
Msg_ReadDeltaUsercmd(&net_message, &null_cmd, &oldest_cmd);
Msg_ReadDeltaUsercmd(&net_message, &oldest_cmd, &old_cmd);
Msg_ReadDeltaUsercmd(&net_message, &old_cmd, &new_cmd);
// don't start delta compression until the client is spawned
// TODO: should this be a little higher up?
if (cl->state != SV_CLIENT_ACTIVE) {
cl->last_frame = -1;
break;
}
// catch extremely high msec movements
if (null_cmd.msec > CMD_MAX_MSEC || oldest_cmd.msec > CMD_MAX_MSEC
|| old_cmd.msec > CMD_MAX_MSEC || new_cmd.msec
> CMD_MAX_MSEC) {
Com_Warn("Sv_ParseClientMessage: Illegal msec from %s\n",
Sv_NetaddrToString(cl));
Sv_KickClient(cl, "Illegal movement");
return;
}
net_drop = cl->netchan.dropped;
if (net_drop < 20) {
while (net_drop > 2) {
Sv_ClientThink(cl, &cl->last_cmd);
net_drop--;
}
if (net_drop > 1)
Sv_ClientThink(cl, &oldest_cmd);
if (net_drop > 0)
Sv_ClientThink(cl, &old_cmd);
}
Sv_ClientThink(cl, &new_cmd);
cl->last_cmd = new_cmd;
break;
case CL_CMD_STRING:
s = Msg_ReadString(&net_message);
// malicious users may try using too many string commands
if (++strings_issued < CMD_MAX_STRINGS)
Sv_UserStringCommand(s);
else {
Com_Warn(
"Sv_ParseClientMessage: CMD_MAX_STRINGS exceeded for %s\n",
Sv_NetaddrToString(cl));
Sv_KickClient(cl, "Too many commands.");
return;
}
if (cl->state == SV_CLIENT_FREE)
return; // disconnect command
break;
default:
Com_Print("Sv_ParseClientMessage: unknown command %d\n", c);
Sv_DropClient(cl);
return;
}
}
}
