blockcheck: always use additional abs split in seqovl to guarantee packet growth

blockcheck.sh

@@ -1232,14 +1232,19 @@ pktws_check_domain_http_bypass_()
 
 		[ "$need_split" = 1 ] && {
 			f="method+2 midsld method+2,midsld"
-			[ "$sec" = 0 ] || f="1 midsld sniext+1 1,midsld"
+			# relative markers can be anywhere, even in subsequent packets. first packet can be MTU-full.
+			# make additional split pos "10" to guarantee enough space for seqovl and likely to be before midsld,sniext,...
+			[ "$sec" = 0 ] || f="10 10,sniext+1 10,midsld"
 			for pos in $f; do
 				pktws_curl_test_update $1 $3 --dpi-desync=multisplit --dpi-desync-split-pos=$pos --dpi-desync-split-seqovl=1 $e && {
 					[ "$SCANLEVEL" = quick ] && return
 					need_wssize=0
 				}
 			done
-			[ "$sec" != 0 ] && pktws_curl_test_update $1 $3 --dpi-desync=multisplit --dpi-desync-split-pos=2 --dpi-desync-split-seqovl=336 --dpi-desync-split-seqovl-pattern="$ZAPRET_BASE/files/fake/tls_clienthello_iana_org.bin" $e && [ "$SCANLEVEL" = quick ] && return
+			[ "$sec" != 0 ] && pktws_curl_test_update $1 $3 --dpi-desync=multisplit --dpi-desync-split-pos=2 --dpi-desync-split-seqovl=336 --dpi-desync-split-seqovl-pattern="$ZAPRET_BASE/files/fake/tls_clienthello_iana_org.bin" $e && {
+				[ "$SCANLEVEL" = quick ] && return
+				need_wssize=0
+			}
 		}
 		[ "$need_disorder" = 1 ] && {
 			if [ "$sec" = 0 ]; then