From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_2 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 98B8BC433ED for ; Wed, 7 Apr 2021 11:49:38 +0000 (UTC) Received: from lists.zx2c4.com (lists.zx2c4.com [165.227.139.114]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id C4F506139B for ; Wed, 7 Apr 2021 11:49:37 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C4F506139B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=wireguard-bounces@lists.zx2c4.com Received: by lists.zx2c4.com (ZX2C4 Mail Server) with ESMTP id 745289ed; Wed, 7 Apr 2021 11:49:36 +0000 (UTC) Received: from desiato.infradead.org (desiato.infradead.org [2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by lists.zx2c4.com (ZX2C4 Mail Server) with ESMTPS id a3b3d9a6 (TLSv1.3:AEAD-AES256-GCM-SHA384:256:NO) for ; Wed, 7 Apr 2021 11:49:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=Mime-Version:Content-Type:Date:Cc:To: From:Subject:Message-ID:Sender:Reply-To:Content-Transfer-Encoding:Content-ID: Content-Description:In-Reply-To:References; bh=G8KJ4FmrBOPzBegdDfU3tO5Gwc25fvLDSWsFG0rfTYw=; b=ASeuQsyx8LHLMLp+pr1bRnxdBh 5v44mgm9Rt+GDp7FDH4sS7ZDnCI8DxacIcG9YE5LxbGjqILkz+amKA8C+04McE0I/zsVA447v8JUE 9q5r+mcJjxxPhCYAJ0gDzi7af01qxe+pZJsEPlrUhnys7pt6L3UsPlT/DMsurdrNXINiw5PdI6ito DdzFopnE5CdBN3XmTN4uzKhdHSm/DcY31jwIjBi45d3LoOToIBR0gOo0r0AkBI3Y8G9Rk5s4KFAvC yc2yaSt4k2AdOuGReb8Mt6g3vf2QQeZDplHSUCC+2Pg2uAf3Z1DxT3zxrPi7vGO41YKbUa+JXlLM7 ++0lnWsQ==; Received: from dyn-234.woodhou.se ([90.155.92.234]) by desiato.infradead.org with esmtpsa (Exim 4.94 #2 (Red Hat Linux)) id 1lU6ga-004uxg-Sr; Wed, 07 Apr 2021 11:49:29 +0000 Message-ID: <6e259ab359c7f93f8f1119df0ba7b285cd4f53d1.camel@infradead.org> Subject: Allowing space for packet headers in Wintun Tx/Rx From: David Woodhouse To: WireGuard mailing list Cc: Daniel Lenski Date: Wed, 07 Apr 2021 12:49:28 +0100 Content-Type: multipart/signed; micalg="sha-256"; protocol="application/x-pkcs7-signature"; boundary="=-niDMxtUqiPsz3/XeYNeo" X-Mailer: Evolution 3.28.5-0ubuntu0.18.04.2 Mime-Version: 1.0 X-SRS-Rewrite: SMTP reverse-path rewritten from by desiato.infradead.org. See http://www.infradead.org/rpr.html X-BeenThere: wireguard@lists.zx2c4.com X-Mailman-Version: 2.1.30rc1 Precedence: list List-Id: Development discussion of WireGuard List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: wireguard-bounces@lists.zx2c4.com Sender: "WireGuard" --=-niDMxtUqiPsz3/XeYNeo Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable My initial port of OpenConnect to use Wintun has a fairly simple implementation for sending and receiving packets. The transmit function is basically this: WintunAllocateSendPacket() memcpy() WintunSendPacket() I don't like the memcpy very much. I'd like to receive and decrypt incoming VPN packets from the public network directly into the Wintun ring. But packets have *headers*. Cisco AnyConnect, for example, has a single byte of 'type' field at the beginning of its DTLS packets. We decrypt the packet we receive from the public network, and *if* the first byte indicates that it's a data packet, we deliver the packet data starting from the second byte onwards into the tun device. So even if I were to receive and decrypt into a buffer allocated with WintunAllocateSendPacket(), I couldn't *send* that without a memmove() to move it all down by one byte. If WintunSendPacket took an additional 'offset' argument to disregard a certain number of bytes at the beginning of the buffer, that would probably suffice. Or is it possible to simply add to the pointer returned by WintunAllocateSendPacket()? Receiving is slightly more complex, as it's too late by the time WintunReceivePacket() is called; the data have already been received into the top of the available space. Perhaps the header reservation for Rx could be an additional parameter to WintunStartSession(), and the requested amount of space would always be available before the pointer returned from WintunReceivePacket()? (It's not clear how to *use* that knowledge in valid and safe C though.) Are there better options? --=-niDMxtUqiPsz3/XeYNeo Content-Type: application/x-pkcs7-signature; name="smime.p7s" Content-Disposition: attachment; filename="smime.p7s" Content-Transfer-Encoding: base64 MIAGCSqGSIb3DQEHAqCAMIACAQExDzANBglghkgBZQMEAgEFADCABgkqhkiG9w0BBwEAAKCCECow ggUcMIIEBKADAgECAhEA4rtJSHkq7AnpxKUY8ZlYZjANBgkqhkiG9w0BAQsFADCBlzELMAkGA1UE BhMCR0IxGzAZBgNVBAgTEkdyZWF0ZXIgTWFuY2hlc3RlcjEQMA4GA1UEBxMHU2FsZm9yZDEaMBgG A1UEChMRQ09NT0RPIENBIExpbWl0ZWQxPTA7BgNVBAMTNENPTU9ETyBSU0EgQ2xpZW50IEF1dGhl bnRpY2F0aW9uIGFuZCBTZWN1cmUgRW1haWwgQ0EwHhcNMTkwMTAyMDAwMDAwWhcNMjIwMTAxMjM1 OTU5WjAkMSIwIAYJKoZIhvcNAQkBFhNkd213MkBpbmZyYWRlYWQub3JnMIIBIjANBgkqhkiG9w0B AQEFAAOCAQ8AMIIBCgKCAQEAsv3wObLTCbUA7GJqKj9vHGf+Fa+tpkO+ZRVve9EpNsMsfXhvFpb8 RgL8vD+L133wK6csYoDU7zKiAo92FMUWaY1Hy6HqvVr9oevfTV3xhB5rQO1RHJoAfkvhy+wpjo7Q cXuzkOpibq2YurVStHAiGqAOMGMXhcVGqPuGhcVcVzVUjsvEzAV9Po9K2rpZ52FE4rDkpDK1pBK+ uOAyOkgIg/cD8Kugav5tyapydeWMZRJQH1vMQ6OVT24CyAn2yXm2NgTQMS1mpzStP2ioPtTnszIQ 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