Default to IPV6_V6ONLY=1 for jsdoor

src/sbbs3/sockopts.c

@@ -58,8 +58,14 @@ int DLLCALL set_socket_options(scfg_t* cfg, SOCKET sock, const char* protocol, c
 
 	/* Set user defined socket options */
 	iniFileName(cfgfile,sizeof(cfgfile),cfg->ctrl_dir,"sockopts.ini");
-	if((fp=iniOpenFile(cfgfile,FALSE))==NULL)
+	if((fp=iniOpenFile(cfgfile,FALSE))==NULL) {
+#ifdef JSDOOR
+		int optval = 1;
+		// Set the only sane choice...
+		setsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY, (void *)&optval, sizeof(optval));
+#endif
 		return(0);
+	}
 	list=iniReadFile(fp);
 	fclose(fp);