Date: Wed, 9 Sep 2009 06:02:40 GMT From: Gaurav Goel <gaurav0287@gmail.com> To: freebsd-gnats-submit@FreeBSD.org Subject: misc/138652: TCP window scaling value Message-ID: <200909090602.n8962eD5077255@www.freebsd.org> Resent-Message-ID: <200909090610.n896A1Aq061417@freefall.freebsd.org>
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>Number: 138652 >Category: misc >Synopsis: TCP window scaling value >Confidential: no >Severity: non-critical >Priority: high >Responsible: freebsd-bugs >State: open >Quarter: >Keywords: >Date-Required: >Class: sw-bug >Submitter-Id: current-users >Arrival-Date: Wed Sep 09 06:10:01 UTC 2009 >Closed-Date: >Last-Modified: >Originator: Gaurav Goel >Release: >Organization: MTree Software Pvt. Ltd. >Environment: >Description: I found in file "tcp_input.c-orig" located at location "usr/src/sys/netinet" at line number 511, "tp->request_r_scale" is incremented depending on condition. 16 bits are reserved for window and its value could be MAX 30 bits. In your if condition "TCP_MAXWIN << tp->request_r_scale < so->so_rcv.sb_hiwat", if I have "so->so_rcv.sb_hiwat" value to be 524286, then "tp->request_r_scale" is incremented four times but its value should be 3. Reason being, while shifting TCP_MAXWIN, 1st iteration 1111111111111111 < 1111111111111111110 [TRUE] increment once 2nd iteration 11111111111111110 < 1111111111111111110 [TRUE] increment again 3rd iteration 111111111111111100 < 1111111111111111110 [TRUE] increment once 4th iteration 1111111111111111000 < 1111111111111111110 [TRUE] increment again 5th iteration 11111111111111110000 < 1111111111111111110 [FALSE] The LSB are zeros, which should be one. Please tell me if I am wrong. >How-To-Repeat: >Fix: >Release-Note: >Audit-Trail: >Unformatted:
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