From owner-freebsd-current@freebsd.org Mon Dec 28 13:15:02 2015 Return-Path: Delivered-To: freebsd-current@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 815AAA53B8F for ; Mon, 28 Dec 2015 13:15:02 +0000 (UTC) (envelope-from oliver.pinter@hardenedbsd.org) Received: from mail-wm0-x232.google.com (mail-wm0-x232.google.com [IPv6:2a00:1450:400c:c09::232]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 11CA914ED for ; Mon, 28 Dec 2015 13:15:02 +0000 (UTC) (envelope-from oliver.pinter@hardenedbsd.org) Received: by mail-wm0-x232.google.com with SMTP id l126so261541482wml.1 for ; Mon, 28 Dec 2015 05:15:01 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=hardenedbsd-org.20150623.gappssmtp.com; s=20150623; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; bh=Q9KPFpaBTLS6f+BHGzARtTTGLzNBLkDmk0X8JE34aE4=; b=B/bhccV4FKYkA0sBOt3syuvPkn15GdX0YSquQoDzH/VX/Qw2ynX2iWUoW+jXCL+HOJ 8QkQDTVHdUil7e9meLVsNPZUUjnqA5/7cwPY99F+Pfn2PdBkbh72rIpc3W8/AI1z1yHR ljXWfFTztlJ7hMZf/IQQGy9e1uSTLZuCYp8MVinSlDL3yjb9uEZJ6h6JJHlADEo8bzyw NYslxFZkb9vwqltZduVSBRRZi0V0CrYpdWipRYzUinLczjlTovP5+JJSUBSvZvanJ8P7 ukJ7DlGDCJnwKxACF5amL9YuqiXoIphx7hH2tMLk6G3rBRgtEZyzA6oUOSvnbHRkcYNd 1EbQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:date :message-id:subject:from:to:cc:content-type; bh=Q9KPFpaBTLS6f+BHGzARtTTGLzNBLkDmk0X8JE34aE4=; b=NelS55/ZxsbzoMSoM53vIRT0LyETfZwNlJ05XM9Jn7R9Od+w5bUyHLnsbz3XVl8nyC CAM8RyihwM0pUP7pmLo2c3cz+MtUT1x387B7BgkIFLz4tMUxCowX410zAH6Cr8FHtT24 +V3CHeHxbyJFf5063oEVuKD0UznHdA1YxtlX/l5zrXFE9eW9JgyZ7ZO+YX6Ta31EBZ1U mOjELmb3UMnbj3TlFSqX/ZQyQ8R603qt1IjfzJskPYmt81bPMgtUt6k4i/HQOtciiB9r 8gcdGrTQBgg+/705GmtEyJGVY7lkAC6Z4CMT8jNKekf4vr6Sqb69tLljWR+CUsLSi4OS j5bg== X-Gm-Message-State: ALoCoQmoiEyvIsI2uimI6QkAAvvQklZeilYbQRHYNJo+UrQP0gnPGFQyjLR0LAFgICkuld3V8JFE5oKiguQkZ8LP5liaUVecqhQMf9/q7ia7CFHNTjQo9t4= MIME-Version: 1.0 X-Received: by 10.28.179.68 with SMTP id c65mr57045595wmf.81.1451308499763; Mon, 28 Dec 2015 05:14:59 -0800 (PST) Received: by 10.194.85.167 with HTTP; Mon, 28 Dec 2015 05:14:59 -0800 (PST) In-Reply-To: References: Date: Mon, 28 Dec 2015 14:14:59 +0100 Message-ID: Subject: Re: TCP Stack: Challenge ACKs and Timestamps From: Oliver Pinter To: Sam Kumar Cc: "freebsd-current@freebsd.org" , gnn@freebsd.org, hiren@freebsd.org Content-Type: text/plain; charset=UTF-8 X-Content-Filtered-By: Mailman/MimeDel 2.1.20 X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 28 Dec 2015 13:15:02 -0000 On Monday, December 28, 2015, Sam Kumar wrote: > Hello, > I am working with the code for the TCP Stack. I noticed that support for > Challenge Acks have been added since the latest release (10.2.0), and I > think I may have found a bug in how they relate to TCP timestamps. All line > numbers below are those in commit e66e064c45687b5d294565dbd829b419848f7992. > > Looking at tcp_input.c, at lines 1594 to 1604, I see code that expects a > timestamp to be in every segment during the session, if they were > negotiated when the connection was being established. > ( > > https://github.com/freebsd/freebsd/blob/master/sys/netinet/tcp_input.c#L1595 > ) > > Looking at tcp_input.c, at lines 2161 and 2188, I see that Challenge ACKs > are sent via calls to tcp_respond(). > ( > > https://github.com/freebsd/freebsd/blob/master/sys/netinet/tcp_input.c#L2161 > and > > https://github.com/freebsd/freebsd/blob/master/sys/netinet/tcp_input.c#L2188 > ) > > Looking at tcp_subr.c, at line 978, I see that the segment sent by > tcp_respond() never contains TCP options. > ( > https://github.com/freebsd/freebsd/blob/master/sys/netinet/tcp_subr.c#L978 > ) > > Therefore, it seems to me that Challenge ACKs will never contain any TCP > options. This violates the condition that once timestamps are negotiated, > they must be present in every segment. > > Please let me know if I am mistaken, or if this is actually a bug. Cc hiren and gnn > > Sam Kumar > _______________________________________________ > freebsd-current@freebsd.org mailing list > https://lists.freebsd.org/mailman/listinfo/freebsd-current > To unsubscribe, send any mail to "freebsd-current-unsubscribe@freebsd.org > " >