Added new CVARs for improved handling of decompression failures:

- `sv_net_incoming_decompression_min_failures`: Min failures required to flag a player - `sv_net_incoming_decompression_max_failures`: max failures allowed before punishment - `sv_net_incoming_decompression_min_failuretime`: Time window for failure tracking
rehlds · Dec 8, 2024 · 64c684a · 64c684a · Splatt581 · Dec 11, 2024
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diff --git a/README.md b/README.md
@@ -63,9 +63,12 @@ This means that plugins that do binary code analysis (Orpheu for example) probab
 <li>sv_rehlds_local_gametime &lt;1|0&gt; // A feature of local gametime which decrease "lags" if you run same map for a long time. Default: 0
 <li>sv_use_entity_file // Use custom entity file for a map. Path to an entity file will be "maps/[map name].ent". 0 - use original entities. 1 - use .ent files from maps directory. 2 - use .ent files from maps directory and create new .ent file if not exist.
 <li>sv_usercmd_custom_random_seed // When enabled server will populate an additional random seed independent of the client. Default: 0
-<li>sv_net_incoming_decompression <1|0> // When enabled server will decompress of incoming compressed file transfer payloads. Default: 1
-<li>sv_net_incoming_decompression_max_ratio <0|100> // Sets the max allowed ratio between compressed and uncompressed data for file transfer. (A ratio close to 90 indicates large uncompressed data with low entropy) Default: 80.0
-<li>sv_net_incoming_decompression_max_size <16|65536> // Sets the max allowed size for decompressed file transfer data. Default: 65536 bytes
+<li>sv_net_incoming_decompression &lt;1|0&gt; // When enabled server will decompress of incoming compressed file transfer payloads. Default: 1
+<li>sv_net_incoming_decompression_max_ratio &lt;0|100&gt; // Sets the max allowed ratio between compressed and uncompressed data for file transfer. (A ratio close to 90 indicates large uncompressed data with low entropy) Default: 80.0
+<li>sv_net_incoming_decompression_max_size &lt;16|65536&gt; // Sets the max allowed size for decompressed file transfer data. Default: 65536 bytes
+<li>sv_net_incoming_decompression_min_failures &lt;0|10&gt; // Sets the min number of decompression failures required before a player's connection is flagged for potential punishment. Default: 4
+<li>sv_net_incoming_decompression_max_failures &lt;0|10&gt; // Sets the max number of decompression failures allowed within a specified time window before action is taken against the player. Default: 10
+<li>sv_net_incoming_decompression_min_failuretime: &lt;0.1|10.0&gt; // Sets the min time in secs within which decompression failures are tracked to determine if the player exceeds the failure thresholds. Default: 0.1
 <li>sv_net_incoming_decompression_punish // Time in minutes for which the player will be banned for malformed/abnormal bzip2 fragments (0 - Permanent, use a negative number for a kick). Default: -1
 <li>sv_tags &lt;comma-delimited string list of tags&gt; // Sets a string defining the "gametags" for this server, this is optional, but if it is set it allows users/scripts to filter in the matchmaking/server-browser interfaces based on the value. Default: ""
 <li>sv_filterban &lt;-1|0|1&gt;// Set packet filtering by IP mode. -1 - All players will be rejected without any exceptions. 0 - No checks will happen. 1 - All incoming players will be checked if they're IP banned (if they have an IP filter entry), if they are, they will be kicked. Default: 1

diff --git a/rehlds/engine/net.h b/rehlds/engine/net.h
@@ -276,6 +276,15 @@ typedef struct flow_s
 	float avgkbytespersec;
 } flow_t;
 
+const int NET_DECOMPRESS_MAX_TIMES = 10;
+
+typedef struct frag_decomp_failure_s
+{
+	float failure_times[NET_DECOMPRESS_MAX_TIMES];
+	// Count of abnormal fragment decompressions in a time window
+	int num_failures;
+} frag_decomp_failure_t;
+
 const int FRAGMENT_C2S_MIN_SIZE = 16;
 const int FRAGMENT_S2C_MIN_SIZE = 256;
 const int FRAGMENT_S2C_MAX_SIZE = 1024;
@@ -422,6 +431,10 @@ typedef struct netchan_s
 
 	// Incoming and outgoing flow metrics
 	flow_t flow[MAX_FLOWS];
+
+	// Stats for decompression of incoming fragments
+	frag_decomp_failure_t frag_decompress[MAX_STREAMS];
+
 } netchan_t;
 
 #ifdef REHLDS_FIXES

diff --git a/rehlds/engine/net_chan.cpp b/rehlds/engine/net_chan.cpp
@@ -40,7 +40,10 @@ cvar_t net_chokeloopback = { "net_chokeloop", "0", 0, 0.0f, nullptr};
 cvar_t sv_net_incoming_decompression = { "sv_net_incoming_decompression", "1", 0, 1.0f, nullptr };
 cvar_t sv_net_incoming_decompression_max_ratio = { "sv_net_incoming_decompression_max_ratio", "80.0", 0, 80.0f, nullptr };
 cvar_t sv_net_incoming_decompression_max_size = { "sv_net_incoming_decompression_max_size", "65536", 0, 65536.0f, nullptr };
-cvar_t sv_net_incoming_decompression_punish = { "sv_net_incoming_decompression_punish", "-1", 0, -1.0f, NULL };
+cvar_t sv_net_incoming_decompression_min_failures = { "sv_net_incoming_decompression_min_failures", "4", 0, 4.0f, nullptr };
+cvar_t sv_net_incoming_decompression_max_failures = { "sv_net_incoming_decompression_max_failures", "10", 0, 10.0f, nullptr };
+cvar_t sv_net_incoming_decompression_min_failuretime = { "sv_net_incoming_decompression_min_failuretime", "0.1", 0, 0.1f, nullptr };
+cvar_t sv_net_incoming_decompression_punish = { "sv_net_incoming_decompression_punish", "-1", 0, -1.0f, nullptr };
 
 cvar_t sv_filetransfercompression = { "sv_filetransfercompression", "1", 0, 0.0f, nullptr};
 cvar_t sv_filetransfermaxsize = { "sv_filetransfermaxsize", "10485760", 0, 0.0f, nullptr};
@@ -171,6 +174,10 @@ void Netchan_Clear(netchan_t *chan)
 		chan->frag_startpos[i] = 0;
 		chan->frag_length[i] = 0;
 		chan->incomingready[i] = FALSE;
+
+		for (int j = 0; j < NET_DECOMPRESS_MAX_TIMES; j++)
+			chan->frag_decompress[i].failure_times[j] = 0;
+		chan->frag_decompress[i].num_failures = 0;
 	}
 
 	if (chan->tempbuffer)
@@ -1423,6 +1430,94 @@ void Netchan_FlushIncoming(netchan_t *chan, int stream)
 	chan->incomingready[stream] = FALSE;
 }
 
+void Netchan_DecompressionCvarsBounds()
+{
+	if (sv_net_incoming_decompression_min_failures.value < 1)
+		Cvar_SetValue("sv_net_incoming_decompression_min_failures", 1);
+
+	else if (sv_net_incoming_decompression_min_failures.value > NET_DECOMPRESS_MAX_TIMES)
+		Cvar_SetValue("sv_net_incoming_decompression_min_failures", NET_DECOMPRESS_MAX_TIMES);
+
+	if (sv_net_incoming_decompression_max_failures.value < 1)
+		Cvar_SetValue("sv_net_incoming_decompression_max_failures", 1);
+
+	else if (sv_net_incoming_decompression_max_failures.value > NET_DECOMPRESS_MAX_TIMES)
+		Cvar_SetValue("sv_net_incoming_decompression_max_failures", NET_DECOMPRESS_MAX_TIMES);
+
+	if (sv_net_incoming_decompression_max_failures.value < sv_net_incoming_decompression_min_failures.value)
+	{
+		int iTemp = sv_net_incoming_decompression_max_failures.value;
+		Cvar_SetValue("sv_net_incoming_decompression_max_failures", sv_net_incoming_decompression_min_failures.value);
+		Cvar_SetValue("sv_net_incoming_decompression_min_failures", iTemp);
+	}
+
+	if (sv_net_incoming_decompression_min_failuretime.value <= 0.0f)
+		Cvar_SetValue("sv_net_incoming_decompression_min_failuretime", 0.1f);
+}
+
+// Check for an abnormal size ratio between compressed and uncompressed data
+qboolean Netchan_ValidateDecompress(netchan_t *chan, int stream, unsigned int compressedSize, unsigned int uncompressedSize)
+{
+#ifdef REHLDS_FIXES
+	int		i;
+	frag_decomp_failure_t	*decomp;
+
+	if (sv_net_incoming_decompression_max_ratio.value <= 0)
+		return TRUE; // validation is disabled
+
+	if (compressedSize >= uncompressedSize)
+		return TRUE;
+
+	float ratio = ((float)(uncompressedSize - compressedSize) / uncompressedSize) * 100.0f;
+	if (ratio < sv_net_incoming_decompression_max_ratio.value)
+		return TRUE; // no low entropy for uncompressed data
+
+	if ((chan->player_slot - 1) != host_client - g_psvs.clients)
+		return TRUE;
+
+	Netchan_DecompressionCvarsBounds();
+
+	decomp = &chan->frag_decompress[stream];
+
+	// check if the client should be rejected based on total failed decompress
+	if (decomp->num_failures >= sv_net_incoming_decompression_max_failures.value)
+	{
+		for (i = 0; i < sv_net_incoming_decompression_max_failures.value - 1; i++)
+			decomp->failure_times[i] = decomp->failure_times[i + 1];
+
+		decomp->num_failures = sv_net_incoming_decompression_max_failures.value - 1;
+	}
+
+	decomp->failure_times[decomp->num_failures++] = realtime;
+
+	// check if the client should be rejected based on recent failed decompress
+	int recent_failures = 0;
+	for (i = 0; i < decomp->num_failures; i++)
+	{
+		if ((realtime - decomp->failure_times[i]) <= sv_net_incoming_decompression_min_failuretime.value)
+			recent_failures++;
+	}
+
+	if (recent_failures >= sv_net_incoming_decompression_min_failures.value)
+	{
+		if (chan->player_slot == 0)
+			Con_DPrintf("Incoming abnormal uncompressed size with ratio %.2f\n", ratio);
+		else
+			Con_DPrintf("%s:Incoming abnormal uncompressed size with ratio %.2f from %s\n", NET_AdrToString(chan->remote_address), ratio, host_client->name);
+
+		if (sv_net_incoming_decompression_punish.value >= 0)
+		{
+			Con_DPrintf("%s:Banned for malformed/abnormal bzip2 fragments from %s\n", NET_AdrToString(chan->remote_address), host_client->name);
+			Cbuf_AddText(va("addip %.1f %s\n", sv_net_incoming_decompression_punish.value, NET_BaseAdrToString(chan->remote_address)));
+		}
+
+		return FALSE;
+	}
+#endif
+
+	return TRUE;
+}
+
 qboolean Netchan_CopyNormalFragments(netchan_t *chan)
 {
 	fragbuf_t *p, *n;
@@ -1483,8 +1578,6 @@ qboolean Netchan_CopyNormalFragments(netchan_t *chan)
 	}
 #endif // REHLDS_FIXES
 
-	qboolean success = TRUE;
-
 	if (*(uint32 *)net_message.data == MAKEID('B', 'Z', '2', '\0'))
 	{
 		// Determine whether decompression of compressed data is allowed
@@ -1493,13 +1586,13 @@ qboolean Netchan_CopyNormalFragments(netchan_t *chan)
 		{
 			if (chan->player_slot == 0)
 			{
-				Con_DPrintf("Incoming compressed data disallowed from\n");
+				Con_DPrintf("Incoming compressed normal fragment disallowed from\n");
 				return FALSE;
 			}
 			// compressed data is expected only after requesting resource list
 			else if (host_client->m_sendrescount == 0)
 			{
-				Con_DPrintf("%s:Incoming compressed data disallowed from %s\n", NET_AdrToString(chan->remote_address), host_client->name);
+				Con_DPrintf("%s:Incoming compressed normal fragment disallowed from %s\n", NET_AdrToString(chan->remote_address), host_client->name);
 				return FALSE;
 			}
 		}
@@ -1510,56 +1603,34 @@ qboolean Netchan_CopyNormalFragments(netchan_t *chan)
 		unsigned int compressedSize   = net_message.cursize - 4;
 
 		// Decompress net buffer data
-		if (success && (BZ2_bzBuffToBuffDecompress(uncompressed, &uncompressedSize, (char *)net_message.data + 4, compressedSize, 1, 0) == BZ_OK))
-		{
-#ifdef REHLDS_FIXES
-			// Check for an abnormal size ratio between compressed and uncompressed data
-			if (sv_net_incoming_decompression_max_ratio.value > 0 && compressedSize < uncompressedSize)
-			{
-				float ratio = ((float)(uncompressedSize - compressedSize) / uncompressedSize) * 100.0f;
-				if (ratio >= sv_net_incoming_decompression_max_ratio.value)
-				{
-					if (chan->player_slot == 0)
-						Con_DPrintf("Incoming abnormal uncompressed size with ratio %.2f\n", ratio);
-					else
-						Con_DPrintf("%s:Incoming abnormal uncompressed size with ratio %.2f from %s\n", NET_AdrToString(chan->remote_address), ratio, host_client->name);
-
-					success = FALSE;
-				}
-			}
-#endif
+		qboolean success = TRUE;
 
-			// Copy uncompressed data back to the net buffer
-			Q_memcpy(net_message.data, uncompressed, uncompressedSize);
-			net_message.cursize = uncompressedSize;
-		}
-		else
+		if (BZ2_bzBuffToBuffDecompress(uncompressed, &uncompressedSize, (char *)net_message.data + 4, compressedSize, 1, 0) != BZ_OK)
 		{
 			// malformed data or compressed data exceeding sv_net_incoming_decompression_max_size
 			success = FALSE;
 		}
+		else if (!Netchan_ValidateDecompress(chan, FRAG_NORMAL_STREAM, compressedSize, uncompressedSize))
+		{
+			success = FALSE;
+		}
 
-		// Drop client if decompression was unsuccessful
+#ifdef REHLDS_FIXES
 		if (!success)
 		{
-			if ((chan->player_slot - 1) == host_client - g_psvs.clients)
-			{
-#ifdef REHLDS_FIXES
-				if (sv_net_incoming_decompression_punish.value >= 0)
-				{
-					Con_DPrintf("%s:Banned for malformed/abnormal bzip2 fragments from %s\n", NET_AdrToString(chan->remote_address), host_client->name);
-					Cbuf_AddText(va("addip %.1f %s\n", sv_net_incoming_decompression_punish.value, NET_BaseAdrToString(chan->remote_address)));
-				}
-#endif
-
-				SV_DropClient(host_client, FALSE, "Malformed/abnormal compressed data");
-			}
-
+			// Drop client if decompression was unsuccessful
+			SV_DropClient(host_client, FALSE, "Malformed/abnormal compressed data");
 			SZ_Clear(&net_message);
+			return FALSE;
 		}
+#endif
+
+		// Copy uncompressed data back to the net buffer
+		Q_memcpy(net_message.data, uncompressed, uncompressedSize);
+		net_message.cursize = uncompressedSize;
 	}
 
-	return success;
+	return TRUE;
 }
 
 qboolean Netchan_CopyFileFragments(netchan_t *chan)
@@ -1575,7 +1646,6 @@ qboolean Netchan_CopyFileFragments(netchan_t *chan)
 	qboolean bCompressed;
 	unsigned int uncompressedSize;
 
-
 	if (!chan->incomingready[FRAG_FILE_STREAM])
 		return FALSE;
 
@@ -1587,6 +1657,19 @@ qboolean Netchan_CopyFileFragments(netchan_t *chan)
 		return FALSE;
 	}
 
+#ifdef REHLDS_FIXES
+	if (chan->player_slot > 0 && (chan->player_slot - 1) == host_client - g_psvs.clients)
+	{
+		// customization already uploaded with request by operator,
+		// do not accept any other customization
+		if (host_client->uploaddoneregistering)
+		{
+			SV_DropClient(host_client, FALSE, "Too many customization have been uploaded (unrequested customization)");
+			return FALSE;
+		}
+	}
+#endif
+
 	bCompressed = FALSE;
 	SZ_Clear(&net_message);
 	MSG_BeginReading();
@@ -1701,10 +1784,53 @@ qboolean Netchan_CopyFileFragments(netchan_t *chan)
 
 	if (bCompressed)
 	{
-		unsigned char* uncompressedBuffer = (unsigned char*)Mem_Malloc(uncompressedSize);
-		Con_DPrintf("Decompressing file %s (%d -> %d)\n", filename, nsize, uncompressedSize);
-		BZ2_bzBuffToBuffDecompress((char*)uncompressedBuffer, &uncompressedSize, (char*)buffer, nsize, 1, 0);
+		// Determine whether decompression of compressed data is allowed
+#ifdef REHLDS_FIXES
+		if (!sv_net_incoming_decompression.value)
+		{
+			if (chan->player_slot == 0)
+			{
+				Con_DPrintf("Incoming compressed file fragment disallowed from\n");
+				return FALSE;
+			}
+			// compressed data is expected only after requesting resource list
+			else if (host_client->m_sendrescount == 0)
+			{
+				Con_DPrintf("%s:Incoming compressed file fragment disallowed from %s\n", NET_AdrToString(chan->remote_address), host_client->name);
+				return FALSE;
+			}
+		}
+#endif
+
+		uncompressedSize = clamp(uncompressedSize, 16u, (unsigned)sv_net_incoming_decompression_max_size.value); // valid range (16 - 65536) bytes
+
+		qboolean success = TRUE;
+		unsigned char *uncompressedBuffer = (unsigned char *)Mem_Malloc(uncompressedSize);
+		unsigned int compressedSize = nsize;
+
+		// Decompress net buffer data
+		if (BZ2_bzBuffToBuffDecompress((char *)uncompressedBuffer, &uncompressedSize, (char *)buffer, compressedSize, 1, 0) != BZ_OK)
+		{
+			// malformed data or compressed data exceeding sv_net_incoming_decompression_max_size
+			success = FALSE;
+		}
+		else if (!Netchan_ValidateDecompress(chan, FRAG_NORMAL_STREAM, compressedSize, uncompressedSize))
+		{
+			success = FALSE;
+		}
+
 		Mem_Free(buffer);
+
+		if (!success)
+		{
+			// Drop client if decompression was unsuccessful
+			SV_DropClient(host_client, FALSE, "Malformed/abnormal compressed data");
+			SZ_Clear(&net_message);
+			Mem_Free(uncompressedBuffer);
+			return FALSE;
+		}
+
+		Con_DPrintf("Decompressing file %s (%d -> %d)\n", filename, compressedSize, uncompressedSize);
 		pos = uncompressedSize;
 		buffer = uncompressedBuffer;
 	}
@@ -1899,6 +2025,9 @@ void Netchan_Init(void)
 	Cvar_RegisterVariable(&sv_net_incoming_decompression);
 	Cvar_RegisterVariable(&sv_net_incoming_decompression_max_ratio);
 	Cvar_RegisterVariable(&sv_net_incoming_decompression_max_size);
+	Cvar_RegisterVariable(&sv_net_incoming_decompression_min_failures);
+	Cvar_RegisterVariable(&sv_net_incoming_decompression_max_failures);
+	Cvar_RegisterVariable(&sv_net_incoming_decompression_min_failuretime);
 	Cvar_RegisterVariable(&sv_net_incoming_decompression_punish);
 #endif
 	Cvar_RegisterVariable(&sv_filetransfermaxsize);