shithub: riscv

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ref: 8cca36db7f4e6bb8ad7842399e227879be393d4b
parent: 5a1c1b590d319d58a178c6d299e99142bf7d4433
author: cinap_lenrek <[email protected]>
date: Sat Sep 17 11:02:51 EDT 2022 

tcpmssclamp: only check the first ipv4 fragment for tcp header


--- a/sys/src/9/ip/tcp.c
+++ b/sys/src/9/ip/tcp.c
@@ -3322,6 +3322,8 @@
 	if((h4->vihl&0xF0)==IP_VER4) {
 		if(h4->proto != IP_TCPPROTO)
 			return;
+		if((h4->frag[0] & (IP_FO>>8)) | (h4->frag[1] & IP_FO))
+			return;
 		if(!(h4->tcpflag[1] & SYN))
 			return;
 		hdrlen = (h4->tcpflag[0] >> 2) & ~3;