Legacy downloader requests have recieved a little TLC.

- Catch buffer overrun opportunities and fail early.
- Add #define MORELEGACYDOWNLOADER for the equivalent of MOREFILENEEDED, but disabled for now because honestly we really shouldn't be encouraging people to use this thing by making it support 255 WADs at once, but also because that'd be MISERABLE to test
- Add a menu report for when legacy downloader attempts fail

src/d_clisrv.c

@@ -1130,6 +1130,7 @@ typedef enum
 	CL_PREPAREHTTPFILES,
 	CL_DOWNLOADHTTPFILES,
 #endif
+	CL_LEGACYREQUESTFAILED,
 } cl_mode_t;
 
 static void GetPackets(void);
@@ -1227,6 +1228,7 @@ static inline void CL_DrawConnectionStatus(void)
 #endif
 			case CL_ASKFULLFILELIST:
 			case CL_CONFIRMCONNECT:
+			case CL_LEGACYREQUESTFAILED:
 				cltext = "";
 				break;
 			case CL_SETUPFILES:
@@ -2124,6 +2126,10 @@ static void M_ConfirmConnect(event_t *ev)
 					{
 						cl_mode = CL_DOWNLOADFILES;
 					}
+					else
+					{
+						cl_mode = CL_LEGACYREQUESTFAILED;
+					}
 				}
 #ifdef HAVE_CURL
 				else
@@ -2279,6 +2285,10 @@ static boolean CL_FinishedFileList(void)
 			{
 				cl_mode = CL_DOWNLOADFILES;
 			}
+			else
+			{
+				cl_mode = CL_LEGACYREQUESTFAILED;
+			}
 		}
 #endif
 	}
@@ -2465,6 +2475,22 @@ static boolean CL_ServerConnectionTicker(const char *tmpsave, tic_t *oldtic, tic
 
 			cl_mode = CL_LOADFILES;
 			break;
+		case CL_LEGACYREQUESTFAILED:
+			{
+				CONS_Printf(M_GetText("Legacy downloader request packet failed.\n"));
+				CONS_Printf(M_GetText("Network game synchronization aborted.\n"));
+				D_QuitNetGame();
+				CL_Reset();
+				D_StartTitle();
+				M_StartMessage(M_GetText(
+					"The legacy file downloader could not handle that many files.\n"
+					"Ask the server host to set up a http source, or\n"
+					"locate and download the necessary files yourself.\n"
+					"\n"
+					"Press ESC\n"
+				), NULL, MM_NOTHING);
+				return false;
+			}
 		case CL_LOADFILES:
 			if (CL_LoadServerFiles()) 
 				cl_mode = CL_SETUPFILES;

src/d_netfil.c

@@ -299,6 +299,9 @@ boolean CL_CheckDownloadable(void)
 	return false;
 }
 
+// The following was written and then quickly deemed too fragile on paper to be worth testing.
+//#DEFINE MORELEGACYDOWNLOADER
+
 /** Sends requests for files in the ::fileneeded table with a status of
   * ::FS_NOTFOUND.
   *
@@ -311,42 +314,102 @@ boolean CL_SendRequestFile(void)
 	char *p;
 	INT32 i;
 	INT64 totalfreespaceneeded = 0, availablefreespace;
+	INT32 skippedafile = -1;
+#ifdef MORELEGACYDOWNLOADER
+	boolean firstloop = true;
+#endif
 
 #ifdef PARANOIA
 	if (M_CheckParm("-nodownload"))
-		I_Error("Attempted to download files in -nodownload mode");
+		I_Error("CL_SendRequestFile: Attempted to download files in -nodownload mode");
+#endif
 
 	for (i = 0; i < fileneedednum; i++)
+	{
+#ifdef PARANOIA
 		if (fileneeded[i].status != FS_FOUND && fileneeded[i].status != FS_OPEN
 			&& (fileneeded[i].willsend == 0 || fileneeded[i].willsend == 2))
 		{
-			I_Error("Attempted to download files that were not sendable");
+			I_Error("CL_SendRequestFile: Attempted to download files that were not sendable");
 		}
 #endif
-
-	netbuffer->packettype = PT_REQUESTFILE;
-	p = (char *)netbuffer->u.textcmd;
-	for (i = 0; i < fileneedednum; i++)
 		if ((fileneeded[i].status == FS_NOTFOUND || fileneeded[i].status == FS_MD5SUMBAD || fileneeded[i].status == FS_FALLBACK))
 		{
+			// Error check for the first time around.
 			totalfreespaceneeded += fileneeded[i].totalsize;
-			nameonly(fileneeded[i].filename);
-			WRITEUINT8(p, i); // fileid
-			WRITESTRINGN(p, fileneeded[i].filename, MAX_WADPATH);
-			// put it in download dir
-			strcatbf(fileneeded[i].filename, downloaddir, "/");
-			fileneeded[i].status = FS_REQUESTED;
 		}
-	WRITEUINT8(p, 0xFF);
+	}
+
 	I_GetDiskFreeSpace(&availablefreespace);
 	if (totalfreespaceneeded > availablefreespace)
 		I_Error("To play on this server you must download %s KB,\n"
 			"but you have only %s KB free space on this drive\n",
 			sizeu1((size_t)(totalfreespaceneeded>>10)), sizeu2((size_t)(availablefreespace>>10)));
 
-	// prepare to download
-	I_mkdir(downloaddir, 0755);
-	return HSendPacket(servernode, true, 0, p - (char *)netbuffer->u.textcmd);
+#ifdef MORELEGACYDOWNLOADER
+tryagain:
+	skippedafile = -1;
+#endif
+
+	netbuffer->packettype = PT_REQUESTFILE;
+	p = (char *)netbuffer->u.textcmd;
+
+	for (i = 0; i < fileneedednum; i++)
+	{
+		if ((fileneeded[i].status == FS_NOTFOUND || fileneeded[i].status == FS_MD5SUMBAD || fileneeded[i].status == FS_FALLBACK))
+		{
+			// Pre-prepare.
+			size_t checklen;
+			nameonly(fileneeded[i].filename);
+
+			// Figure out if we'd overrun our buffer.
+			checklen = strlen(fileneeded[i].filename)+2; // plus the fileid (and terminator, in case this is last)
+			if ((UINT8 *)(p + checklen) > netbuffer->u.textcmd + MAXTEXTCMD-1)
+			{
+				skippedafile = i;
+				// we might have a shorter file that can fit in the remaining space, and file ID permits out-of-order data
+				continue;
+			}
+
+			// Now write.
+			WRITEUINT8(p, i); // fileid
+			WRITESTRINGN(p, fileneeded[i].filename, MAX_WADPATH);
+
+			// put it in download dir
+			strcatbf(fileneeded[i].filename, downloaddir, "/");
+			fileneeded[i].status = FS_REQUESTED;
+		}
+	}
+
+#ifdef MORELEGACYDOWNLOADER
+	if (firstloop)
+#else
+	// If we're not trying extralong legacy download requests, gotta bail.
+	if (skippedafile != -1)
+		return false;
+	else
+#endif
+		I_mkdir(downloaddir, 0755);
+
+#ifdef PARANOIA
+	// Couldn't fit a single one in?
+	if (p == (char *)netbuffer->u.textcmd)
+		I_Error("CL_SendRequestFile: Fileneeded name for %s (fileneeded[%d]) too long??", (p > 0 ? fileneeded[p].filename : NULL), p);
+#endif
+
+	WRITEUINT8(p, 0xFF); // terminator
+	if (!HSendPacket(servernode, true, 0, p - (char *)netbuffer->u.textcmd))
+		return false;
+
+#ifdef MORELEGACYDOWNLOADER
+	if (skippedafile != -1)
+	{
+		firstloop = false;
+		goto tryagain;
+	}
+#endif
+
+	return true;
 }
 
 // get request filepak and put it on the send queue
@@ -362,10 +425,10 @@ boolean Got_RequestFilePak(INT32 node)
 		if (id == 0xFF)
 			break;
 		READSTRINGN(p, wad, MAX_WADPATH);
-		if (!SV_SendFile(node, wad, id))
+		if (p >= netbuffer->u.textcmd + MAXTEXTCMD-1 || !SV_SendFile(node, wad, id))
 		{
 			SV_AbortSendFiles(node);
-			return false; // don't read the rest of the files
+			return false; // don't read any more
 		}
 	}
 	return true; // no problems with any files