From sacadmin Wed Oct 3 03:13:18 2007 Received: from sac.sfbay.sun.com (localhost [127.0.0.1]) by sac.sfbay.sun.com (8.13.8+Sun/8.13.8) with ESMTP id l93ADIL7018804; Wed, 3 Oct 2007 03:13:18 -0700 (PDT) Received: (from meem@localhost) by sac.sfbay.sun.com (8.13.8+Sun/8.13.8/Submit) id l93ADIi4018801; Wed, 3 Oct 2007 03:13:18 -0700 (PDT) Date: Wed, 3 Oct 2007 03:13:18 -0700 (PDT) From: Peter Memishian Message-Id: <200710031013.l93ADIi4018801@sac.sfbay.sun.com> To: PSARC-record@sac.sfbay.sun.com Cc: clearview-discuss@opensolaris.org Subject: IP_DHCPINIT_IF socket option [PSARC/2007/571 FastTrack timeout 10/9/2007] Status: RO Content-Length: 567 Template Version: @(#)sac_nextcase 1.64 07/13/07 SMI This information is Copyright 2007 Sun Microsystems 1. Introduction 1.1. Project/Component Working Name: IP_DHCPINIT_IF socket option 1.2. Name of Document Author/Supplier: Author: Peter Memishian 1.3 Date of This Document: 03 October, 2007 4. Technical Description See the case directory for more detail 6. Resources and Schedule 6.4. Steering Committee requested information 6.4.1. Consolidation C-team Name: ON 6.5. ARC review type: FastTrack 6.6. ARC Exposure: open From peter.memishian@sun.com Wed Oct 3 03:15:23 2007 Received: from sunmail4.Singapore.Sun.COM (sunmail4.Singapore.Sun.COM [129.158.71.19]) by sac.sfbay.sun.com (8.13.8+Sun/8.13.8) with ESMTP id l93AFM0M018952 for ; Wed, 3 Oct 2007 03:15:22 -0700 (PDT) Received: from brm-avmta-1.central.sun.com (brm-avmta-1.Central.Sun.COM [129.147.4.11]) by sunmail4.Singapore.Sun.COM (8.13.4+Sun/8.13.3/ENSMAIL,v2.2) with ESMTP id l93AC7rA006669 for <@sunmail2sca.sfbay.sun.com:psarc-ext@sun.com>; Wed, 3 Oct 2007 18:12:12 +0800 (SGT) Received: from pmxchannel-daemon.brm-avmta-1.central.sun.com by brm-avmta-1.central.sun.com (Sun Java System Messaging Server 6.2-3.04 (built Jul 15 2005)) id <0JPB00503Z095900@brm-avmta-1.central.sun.com> for psarc-ext@sun.com (ORCPT psarc-ext@sun.com); Wed, 03 Oct 2007 04:12:09 -0600 (MDT) Received: from dhcp-cbjs05-219-56.PRC.Sun.COM ([129.158.219.180]) by brm-avmta-1.central.sun.com (Sun Java System Messaging Server 6.2-3.04 (built Jul 15 2005)) with ESMTP id <0JPB00MYKZ07DJC0@brm-avmta-1.central.sun.com> for psarc-ext@sun.com (ORCPT psarc-ext@sun.com); Wed, 03 Oct 2007 04:12:08 -0600 (MDT) Received: from dhcp-cbjs05-219-56.PRC.Sun.COM (localhost [127.0.0.1]) by dhcp-cbjs05-219-56.PRC.Sun.COM (8.14.1+Sun/8.14.1) with ESMTP id l93ABm50027411; Wed, 03 Oct 2007 18:11:48 +0800 (CST) Received: (from meem@localhost) by dhcp-cbjs05-219-56.PRC.Sun.COM (8.14.1+Sun/8.14.1/Submit) id l93ABm9W027408; Wed, 03 Oct 2007 18:11:48 +0800 (CST) Date: Wed, 03 Oct 2007 18:11:47 +0800 From: Peter Memishian Subject: PSARC/2007/571 IP_DHCPINIT_IF socket option To: psarc-ext@sun.com Cc: clearview-discuss@opensolaris.org Reply-to: peter.memishian@sun.com Message-id: <18179.27363.890925.900350@dhcp-cbjs05-219-56.PRC.Sun.COM> MIME-version: 1.0 X-Mailer: VM 7.17 under 21.4 (patch 19) "Constant Variable" XEmacs Lucid Content-type: text/plain; charset=us-ascii Content-transfer-encoding: 7BIT X-PMX-Version: 5.2.0.264296 X-Authentication-warning: dhcp-cbjs05-219-56.PRC.Sun.COM: meem set sender to peter.memishian@sun.com using -f Status: RO Content-Length: 4309 I'm sponsoring this case for myself. The timeout is set for 10/9/2007. Overview -------- This case proposes a new IP_DHCPINIT_IF socket option that allows our DHCP client to be entirely sockets-based while maintaining maximum interoperability with DHCP servers. The proposed stability is Consolidation Private, and patch binding is requested. Details ------- While DHCP is a UDP-based protocol and thus in theory our DHCP client should be able to use the standard sockets-based API to obtain a lease for an IPv4 address, subtleties in our IP implementation and in the DHCP protocol definition itself have thus far prevented this. As a result, our DHCP client instead makes use of the low-level DLPI API until a lease on an IPv4 address has been obtained, and then switches over to sockets. Complexity and code duplication issues aside (e.g., the client has to do its own UDP and IP checksum calculations when using DLPI), use of DLPI prevents DHCP from working with IP-layer technologies such as IPMP, sidesteps IP Filter policies for DHCP traffic, and interferes with Dynamic Reconfiguration (e.g., an IP interface trying to obtain a DHCP lease via DLPI will cause DR removal of the underlying link to fail). Thus, we'd like to update the DHCP client to be sockets-based. By and large, resolving the necessary issues to allow this have been straightforward. One difficulty remains: handling DHCPOFFER and DHCPACK packets sent by the DHCP server to the DHCP client prior to the client obtaining a lease. Specifically, RFC2131 (which details DHCP) states: If 'giaddr' is zero and 'ciaddr' is zero, and the broadcast bit is set, then the server broadcasts DHCPOFFER and DHCPACK messages to 0xffffffff. If the broadcast bit is not set and 'giaddr' is zero and 'ciaddr' is zero, then the server _unicasts_ DHCPOFFER and DHCPACK messages to the client's hardware address _and_ 'yiaddr' address. [ Note that "yiaddr" is the IP address being offered to the client which it has no a priori knowledge of. ] ... and then goes on to state: The BROADCAST bit will provide a _hint_ to the DHCP server and BOOTP relay agent to broadcast any messages to the client on the client's subnet. That is, even if the client sets the broadcast bit, the server is free to ignore the bit and unicast the DHCPOFFER and DHCPACK packets back to the client. Indeed, it seems that not all DHCP server implementations respect the broadcast bit -- as evidenced by this Microsoft knowledge base article: http://support.microsoft.com/kb/928233 Thus, to preserve interoperability, we propose a simple but admittedly unfortunate socket option: IP_DHCPINIT_IF. As with other IP_*_IF socket options, IP_DHCPINIT_IF takes a pointer to an integer indicating the IP interface to enable "DHCPINIT" mode on. Once DHCPINIT mode is enabled on an interface, the IP module will treat any IP unicast DHCP packets received on that interface as if they were sent to an IP address that was owned by the system. This will allow the DHCP client (which will have a socket bound to INADDR_ANY and the appropriate DHCP port) to receive the packets. The DHCP client will then -- as usual -- perform filtering based on the "xid" contained with the DHCP portion of the packet to determine if the packet is a response to a previous request. As with other IP_*_IF socket options, only one interface may be placed in IP_DHCPINIT_IF mode on a given socket at a time, and specifying an interface index of zero disables the socket option. Closing the socket also disables the socket option. Multiple consumers of IP_DHCPINIT_IF will not interfere with one another -- that is, the interface will remain in DHCPINIT mode as long as there as at least one socket that has enabled IP_DHCPINIT_IF for that interface. Because enabling IP_DHCPINIT_IF disables the IP "fastpath", use of IP_DHCPINIT_IF will require PRIV_SYS_IP_CONFIG. The DHCP client will only use IP_DHCPINIT_IF during lease acquisition (the period where DLPI is currently used). Because DHCPv6 uses IPv6 link-local addresses, it sidesteps this issue entirely. Thus, no IPV6_DHCPINIT_IF is necessary. -- meem From meem@triplex.east.sun.com Tue Oct 9 21:17:27 2007 Received: from sunmail5.uk.sun.com (sunmail5.UK.Sun.COM [129.156.85.165]) by sac.sfbay.sun.com (8.13.8+Sun/8.13.8) with ESMTP id l9A4HQgB025986 for ; Tue, 9 Oct 2007 21:17:26 -0700 (PDT) Received: from brm-avmta-1.central.sun.com (brm-avmta-1.Central.Sun.COM [129.147.4.11]) by sunmail5.uk.sun.com (8.13.7+Sun/8.13.7/ENSMAIL,v2.2) with ESMTP id l9A4E4MB024532; Wed, 10 Oct 2007 05:14:09 +0100 (BST) Received: from pmxchannel-daemon.brm-avmta-1.central.sun.com by brm-avmta-1.central.sun.com (Sun Java System Messaging Server 6.2-3.04 (built Jul 15 2005)) id <0JPO00A07H3K8100@brm-avmta-1.central.sun.com>; Tue, 09 Oct 2007 22:14:08 -0600 (MDT) Received: from triplex.East.Sun.COM ([129.148.174.104]) by brm-avmta-1.central.sun.com (Sun Java System Messaging Server 6.2-3.04 (built Jul 15 2005)) with ESMTP id <0JPO00AATH3I0C00@brm-avmta-1.central.sun.com>; Tue, 09 Oct 2007 22:14:07 -0600 (MDT) Received: from triplex.East.Sun.COM (localhost [127.0.0.1]) by triplex.East.Sun.COM (8.14.1+Sun/8.14.1) with ESMTP id l9A46bIQ407986; Wed, 10 Oct 2007 00:06:37 -0400 (EDT) Received: (from meem@localhost) by triplex.East.Sun.COM (8.14.1+Sun/8.14.1/Submit) id l9A46bVx407983; Wed, 10 Oct 2007 00:06:37 -0400 (EDT) Date: Wed, 10 Oct 2007 00:06:36 -0400 From: Peter Memishian Subject: re: [clearview-discuss] PSARC/2007/571 IP_DHCPINIT_IF socket option In-reply-to: <18179.27363.890925.900350@dhcp-cbjs05-219-56.PRC.Sun.COM> To: peter.memishian@sun.com Cc: psarc-ext@sun.com, clearview-discuss@opensolaris.org Message-id: <18188.20428.587483.853205@gargle.gargle.HOWL> MIME-version: 1.0 X-Mailer: VM 7.17 under 21.4 (patch 18) "Social Property" XEmacs Lucid Content-type: text/plain; charset=us-ascii Content-transfer-encoding: 7BIT X-PMX-Version: 5.2.0.264296 References: <18179.27363.890925.900350@dhcp-cbjs05-219-56.PRC.Sun.COM> Status: RO Content-Length: 131 > I'm sponsoring this case for myself. The timeout is set for 10/9/2007. This case has timed out and is now approved. -- meem