Merge branch 'hole-punch-backport' into 'public_next'

Hole punching backport

See merge request KartKrew/Kart!445

doc/Holepunch-Protocol.txt

@@ -0,0 +1,34 @@
+             Bird's Hole Punching Protocol
+
+
+Hole punch - a mechanism to bypass a firewall
+Server     - a third party which is not behind a firewall
+Client     - anything contacting the server
+Magic      - the four bytes 00 52 EB 11
+Address    - an IPv4 address
+
+
+                  0 1 2 3 4 5 6 7 8  9
+                 +-------+-------+----+
+                 | Magic |Address|Port|
+                 +-------+-------+----+
+                      Relay Packet
+
+
+A client that expects to be the target of a hole punch
+must contact the server frequently, to keep a UDP
+"connection" open, so that the server may relay hole
+punching requests to them.
+
+A client makes a hole punching request to another client
+by sending a Relay Packet to the server. The server then
+sends another Relay Packet to the client described by the
+first packet. The second packet is filled with the source
+address and port of the first packet.
+
+Once a client receives a Relay Packet, this protocol's
+purpose is fulfilled and the client is aware that another
+client requests a hole punch.
+
+
+vim: noai

src/d_clisrv.c

@@ -1916,6 +1916,12 @@ static void SendAskInfo(INT32 node)
 	// now allowed traffic from the host to us in, so once the MS relays
 	// our address to the host, it'll be able to speak to us.
 	HSendPacket(node, false, 0, sizeof (askinfo_pak));
+
+	if (node != 0 && node != BROADCASTADDR &&
+			cv_rendezvousserver.string[0])
+	{
+		I_NetRequestHolePunch();
+	}
 }
 
 serverelem_t serverlist[MAXSERVERLIST];
@@ -5754,6 +5760,22 @@ static void UpdatePingTable(void)
 	}
 }
 
+static void RenewHolePunch(void)
+{
+	if (cv_rendezvousserver.string[0])
+	{
+		static time_t past;
+
+		const time_t now = time(NULL);
+
+		if ((now - past) > 20)
+		{
+			I_NetRegisterHolePunch();
+			past = now;
+		}
+	}
+}
+
 // Handle timeouts to prevent definitive freezes from happenning
 static void HandleNodeTimeouts(void)
 {
@@ -5788,6 +5810,11 @@ FILESTAMP
 	MasterClient_Ticker();
 #endif
 
+	if (netgame && serverrunning)
+	{
+		RenewHolePunch();
+	}
+
 	if (client)
 	{
 		// send keep alive
@@ -5847,6 +5874,11 @@ FILESTAMP
 	MasterClient_Ticker(); // Acking the Master Server
 #endif
 
+	if (netgame && serverrunning)
+	{
+		RenewHolePunch();
+	}
+
 	if (client)
 	{
 		if (!resynch_local_inprogress)

src/d_net.c

@@ -49,6 +49,8 @@ tic_t connectiontimeout = (10*TICRATE);
 doomcom_t *doomcom = NULL;
 /// \brief network packet data, points inside doomcom
 doomdata_t *netbuffer = NULL;
+/// \brief hole punching packet, also points inside doomcom
+holepunch_t *holepunchpacket = NULL;
 
 #ifdef DEBUGFILE
 FILE *debugfile = NULL; // put some net info in a file during the game
@@ -72,6 +74,8 @@ boolean (*I_NetCanGet)(void) = NULL;
 void (*I_NetCloseSocket)(void) = NULL;
 void (*I_NetFreeNodenum)(INT32 nodenum) = NULL;
 SINT8 (*I_NetMakeNodewPort)(const char *address, const char* port) = NULL;
+void (*I_NetRequestHolePunch)(void) = NULL;
+void (*I_NetRegisterHolePunch)(void) = NULL;
 boolean (*I_NetOpenSocket)(void) = NULL;
 boolean (*I_Ban) (INT32 node) = NULL;
 void (*I_ClearBans)(void) = NULL;
@@ -1335,6 +1339,7 @@ boolean D_CheckNetGame(void)
 		I_Error("Too many nodes (%d), max:%d", doomcom->numnodes, MAXNETNODES);
 
 	netbuffer = (doomdata_t *)(void *)&doomcom->data;
+	holepunchpacket = (holepunch_t *)(void *)&doomcom->data;
 
 #ifdef DEBUGFILE
 #ifdef _arch_dreamcast

src/i_net.h

@@ -77,11 +77,19 @@ typedef struct
 	char data[MAXPACKETLENGTH];
 } ATTRPACK doomcom_t;
 
+typedef struct
+{
+	INT32 magic;
+	INT32 addr;
+	INT16 port;
+} ATTRPACK holepunch_t;
+
 #if defined(_MSC_VER)
 #pragma pack()
 #endif
 
 extern doomcom_t *doomcom;
+extern holepunch_t *holepunchpacket;
 
 /**	\brief return packet in doomcom struct
 */
@@ -140,6 +148,15 @@ extern boolean (*I_NetOpenSocket)(void);
 extern void (*I_NetCloseSocket)(void);
 
 
+/**	\brief send a hole punching request
+*/
+extern void (*I_NetRequestHolePunch)(void);
+
+/**	\brief register this machine on the hole punching server
+*/
+extern void (*I_NetRegisterHolePunch)(void);
+
+
 extern boolean (*I_Ban) (INT32 node);
 extern void (*I_ClearBans)(void);
 extern const char *(*I_GetNodeAddress) (INT32 node);

src/i_tcp.c

@@ -241,6 +241,8 @@ static size_t broadcastaddresses = 0;
 static boolean nodeconnected[MAXNETNODES+1];
 static mysockaddr_t banned[MAXBANS];
 static UINT8 bannedmask[MAXBANS];
+/* See ../doc/Holepunch-Protocol.txt */
+static const INT32 hole_punch_magic = MSBF_LONG (0x52eb11);
 #endif
 
 static size_t numbans = 0;
@@ -597,6 +599,55 @@ void Command_Numnodes(void)
 #endif
 
 #ifndef NONET
+/* not one of the reserved "local" addresses */
+static boolean
+is_external_address (UINT32 p)
+{
+	UINT8 a = (p & 255);
+	UINT8 b = ((p >> 8) & 255);
+
+	if (p == (UINT32)~0)/* 255.255.255.255 */
+		return 0;
+
+	switch (a)
+	{
+		case 0:
+		case 10:
+		case 127:
+			return false;
+		case 172:
+			return (b & ~15) != 16;/* 16 - 31 */
+		case 192:
+			return b != 168;
+		default:
+			return true;
+	}
+}
+
+static boolean hole_punch(ssize_t c)
+{
+	/* See ../doc/Holepunch-Protocol.txt */
+	if (cv_rendezvousserver.string[0] &&
+			c == 10 && holepunchpacket->magic == hole_punch_magic &&
+			is_external_address(ntohl(holepunchpacket->addr)))
+	{
+		mysockaddr_t addr;
+		addr.ip4.sin_family      = AF_INET;
+		addr.ip4.sin_addr.s_addr = holepunchpacket->addr;
+		addr.ip4.sin_port        = holepunchpacket->port;
+		sendto(mysockets[0], NULL, 0, 0, &addr.any, sizeof addr.ip4);
+
+		CONS_Debug(DBG_NETPLAY,
+				"hole punching request from %s\n", SOCK_AddrToStr(&addr));
+
+		return true;
+	}
+	else
+	{
+		return false;
+	}
+}
+
 // Returns true if a packet was received from a new node, false in all other cases
 static boolean SOCK_Get(void)
 {
@@ -611,7 +662,7 @@ static boolean SOCK_Get(void)
 		fromlen = (socklen_t)sizeof(fromaddress);
 		c = recvfrom(mysockets[n], (char *)&doomcom->data, MAXPACKETLENGTH, 0,
 			(void *)&fromaddress, &fromlen);
-		if (c != ERRSOCKET)
+		if (c > 0)
 		{
 #ifdef USE_STUN
 			if (STUN_got_response(doomcom->data, c))
@@ -620,6 +671,11 @@ static boolean SOCK_Get(void)
 			}
 #endif
 
+			if (hole_punch(c))
+			{
+				return false;
+			}
+
 			// find remote node number
 			for (j = 1; j <= MAXNETNODES; j++) //include LAN
 			{
@@ -1319,17 +1375,14 @@ void I_ShutdownTcpDriver(void)
 }
 
 #ifndef NONET
-static SINT8 SOCK_NetMakeNodewPort(const char *address, const char *port)
+static boolean SOCK_GetAddr(struct sockaddr_in *sin, const char *address, const char *port, boolean test)
 {
-	SINT8 newnode = -1;
 	struct my_addrinfo *ai = NULL, *runp, hints;
 	int gaie;
 
 	if (!port || !port[0])
 		port = DEFAULTPORT;
 
-	DEBFILE(va("Creating new node: %s@%s\n", address, port));
-
 	memset (&hints, 0x00, sizeof (hints));
 	hints.ai_flags = 0;
 	hints.ai_family = AF_UNSPEC;
@@ -1337,31 +1390,94 @@ static SINT8 SOCK_NetMakeNodewPort(const char *address, const char *port)
 	hints.ai_protocol = IPPROTO_UDP;
 
 	gaie = I_getaddrinfo(address, port, &hints, &ai);
-	if (gaie == 0)
+
-	{
+	if (gaie != 0)
-		newnode = getfreenode();
-	}
-	if (newnode == -1)
 	{
 		I_freeaddrinfo(ai);
-		return -1;
+		return false;
 	}
-	else
+
 	runp = ai;
 
+	if (test)
+	{
 		while (runp != NULL)
 		{
-		// find ip of the server
 			if (sendto(mysockets[0], NULL, 0, 0, runp->ai_addr, runp->ai_addrlen) == 0)
-		{
-			memcpy(&clientaddress[newnode], runp->ai_addr, runp->ai_addrlen);
 				break;
-		}
+
 			runp = runp->ai_next;
 		}
+	}
+
+	if (runp != NULL)
+		memcpy(sin, runp->ai_addr, runp->ai_addrlen);
+
 	I_freeaddrinfo(ai);
+
+	return (runp != NULL);
+}
+
+static SINT8 SOCK_NetMakeNodewPort(const char *address, const char *port)
+{
+	SINT8 newnode = getfreenode();
+
+	DEBFILE(va("Creating new node: %s@%s\n", address, port));
+
+	if (newnode != -1)
+	{
+		if (!SOCK_GetAddr(&clientaddress[newnode].ip4, address, port, true))
+		{
+			nodeconnected[newnode] = false;
+			return -1;
+		}
+	}
+
 	return newnode;
 }
+
+/* See ../doc/Holepunch-Protocol.txt */
+
+static void rendezvous(int size)
+{
+	char *addrs = strdup(cv_rendezvousserver.string);
+
+	char *host = strtok(addrs, ":");
+	char *port = strtok(NULL,  ":");
+
+	mysockaddr_t rzv;
+
+	if (SOCK_GetAddr(&rzv.ip4, host, (port ? port : "7777"), false))
+	{
+		holepunchpacket->magic = hole_punch_magic;
+		sendto(mysockets[0], doomcom->data, size, 0, &rzv.any, sizeof rzv.ip4);
+	}
+	else
+	{
+		CONS_Alert(CONS_ERROR, "Failed to contact rendezvous server (%s).\n",
+				cv_rendezvousserver.string);
+	}
+
+	free(addrs);
+}
+
+static void SOCK_RequestHolePunch(void)
+{
+	mysockaddr_t * addr = &clientaddress[doomcom->remotenode];
+
+	holepunchpacket->addr = addr->ip4.sin_addr.s_addr;
+	holepunchpacket->port = addr->ip4.sin_port;
+
+	CONS_Debug(DBG_NETPLAY,
+			"requesting hole punch to node %s\n", SOCK_AddrToStr(addr));
+
+	rendezvous(10);
+}
+
+static void SOCK_RegisterHolePunch(void)
+{
+	rendezvous(4);
+}
 #endif
 
 static boolean SOCK_OpenSocket(void)
@@ -1387,6 +1503,9 @@ static boolean SOCK_OpenSocket(void)
 	I_NetCanGet = SOCK_CanGet;
 #endif
 
+	I_NetRequestHolePunch = SOCK_RequestHolePunch;
+	I_NetRegisterHolePunch = SOCK_RegisterHolePunch;
+
 	// build the socket but close it first
 	SOCK_CloseSocket();
 	return UDP_Socket();

src/mserv.c

@@ -68,6 +68,7 @@ static CV_PossibleValue_t masterserver_update_rate_cons_t[] = {
 };
 
 consvar_t cv_masterserver = {"masterserver", "https://ms.kartkrew.org/ms/api", CV_SAVE|CV_CALL, NULL, MasterServer_OnChange, 0, NULL, NULL, 0, 0, NULL};
+consvar_t cv_rendezvousserver = {"rendezvousserver", "relay.kartkrew.org", CV_SAVE, NULL, NULL, 0, NULL, NULL, 0, 0, NULL};
 consvar_t cv_servername = {"servername", "SRB2Kart server", CV_SAVE|CV_CALL|CV_NOINIT, NULL, Update_parameters, 0, NULL, NULL, 0, 0, NULL};
 consvar_t cv_server_contact = {"server_contact", "", CV_SAVE|CV_CALL|CV_NOINIT, NULL, Update_parameters, 0, NULL, NULL, 0, 0, NULL};
 
@@ -99,6 +100,7 @@ void AddMServCommands(void)
 	CV_RegisterVar(&cv_masterserver_debug);
 	CV_RegisterVar(&cv_masterserver_token);
 	CV_RegisterVar(&cv_advertise);
+	CV_RegisterVar(&cv_rendezvousserver);
 	CV_RegisterVar(&cv_servername);
 	CV_RegisterVar(&cv_server_contact);
 #ifdef MASTERSERVER

src/mserv.h

@@ -58,6 +58,7 @@ extern consvar_t cv_masterserver_update_rate;
 extern consvar_t cv_masterserver_timeout;
 extern consvar_t cv_masterserver_debug;
 extern consvar_t cv_masterserver_token;
+extern consvar_t cv_rendezvousserver;
 
 extern consvar_t cv_advertise;