From 7eb5755963e26479d5d66337418a65c5116b8537 Mon Sep 17 00:00:00 2001
From: AJ Martinez <aj@tyronesama.moe>
Date: Sun, 2 Apr 2023 00:01:34 -0700
Subject: [PATCH] Disallow duplicate non-GUEST pubkeys

---
 src/d_clisrv.c | 37 ++++++++++++++++++++++++++++++++-----
 1 file changed, 32 insertions(+), 5 deletions(-)

diff --git a/src/d_clisrv.c b/src/d_clisrv.c
index f1ff9cf96..d2f1b1ac1 100644
--- a/src/d_clisrv.c
+++ b/src/d_clisrv.c
@@ -4297,7 +4297,7 @@ static boolean IsPlayerGuest(int player)
 static void HandleConnect(SINT8 node)
 {
 	char names[MAXSPLITSCREENPLAYERS][MAXPLAYERNAME + 1];
-	INT32 i;
+	INT32 i, j;
 	UINT8 availabilitiesbuffer[MAXAVAILABILITY];
 
 	// Sal: Dedicated mode is INCREDIBLY hacked together.
@@ -4396,6 +4396,8 @@ static void HandleConnect(SINT8 node)
 	{
 		int sigcheck;
 		boolean newnode = false;
+		char allZero[PUBKEYLENGTH];
+		memset(allZero, 0, sizeof(allZero));
 
 		for (i = 0; i < netbuffer->u.clientcfg.localplayers - playerpernode[node]; i++)
 		{
@@ -4411,10 +4413,7 @@ static void HandleConnect(SINT8 node)
 				memcpy(lastReceivedKey[node][i], PR_GetLocalPlayerProfile(i)->public_key, sizeof(lastReceivedKey[node][i]));
 			}
 			else // Remote player, gotta check their signature.
-			{
-				char allZero[PUBKEYLENGTH];
-				memset(allZero, 0, sizeof(allZero));
-				
+			{	
 				if (memcmp(lastReceivedKey[node][i], allZero, PUBKEYLENGTH) == 0) // IsSplitPlayerOnNodeGuest isn't appropriate here, they're not in-game yet!
 				{
 					if (!cv_allowguests.value)
@@ -4436,6 +4435,34 @@ static void HandleConnect(SINT8 node)
 					return;
 				}
 			}
+
+			// Check non-GUESTS for duplicate pubkeys, they'll create nonsense stats
+			if (memcmp(lastReceivedKey[node][i], allZero, PUBKEYLENGTH) != 0)
+			{
+				// Players already here
+				for (j = 0; j < MAXPLAYERS; j++)
+				{
+					if (memcmp(lastReceivedKey[node][i], players[j].public_key, PUBKEYLENGTH) == 0)
+					{
+						SV_SendRefuse(node, M_GetText("Duplicate pubkey already on server.\n(Did you share your profile?)"));
+						return;	
+					}
+				}
+
+				// Players we're trying to add
+				for (j = 0; j < netbuffer->u.clientcfg.localplayers - playerpernode[node]; j++)
+				{
+					if (memcmp(lastReceivedKey[node][i], allZero, PUBKEYLENGTH) == 0)
+						continue;
+					if (i == j)
+						continue;
+					if (memcmp(lastReceivedKey[node][i], lastReceivedKey[node][j], PUBKEYLENGTH) == 0)
+					{
+						SV_SendRefuse(node, M_GetText("Duplicate pubkey in local party.\n(How did you even do this?)"));
+						return;	
+					}
+				}
+			}
 		}
 
 		memcpy(availabilitiesbuffer, netbuffer->u.clientcfg.availabilities, sizeof(availabilitiesbuffer));