Linux kernel, Android, Golang & Recsys

今天在wikipedia看IGMP的时候，无意中发现了XORP, 简单适用了一下非常好用，并且官方的资料真理的比较全，使用也比较方便，还提供了一个基本的shell xorpsh 来配置管理信息。刚好可以省去买支持IGMP的路由器，支持IGMP的路由器最少也要1.5W…

XORP, or Extensible Open Router Platform, is an open source routing software suite, aimed at being both stable and fully featured enough for production use and also extensible to support networking research.

Request:
OS: ubuntu 9.04 (Linux Kernel 2.6.28-11-generic) with GCC 4.3.3
SW: XORP (multicast routing daemon)
HW: PC with 2 or 3 ethernet card (default gw is itself) !

Step 1: Check Linux Kernel Functions!
CONFIG_IP_MULTICAST=y
CONFIG_IP_ADVANCED_ROUTER=y
CONFIG_IP_MROUTE=y
After this configurations, the linux kernel support IGMP, DVMRP and MOSPF. If want support PIM-SM , do below settings
CONFIG_IP_PIMSM_V2=y
PS: you can use vi view /boot/CONFIG-(kernel version) to confirm !

Step 2: edit /etc/sysctl.conf to enable ip_forward
net.ipv4.conf.default.forwarding=1
PS: reboot or use command “sysctl -p” to enable !

Step 3: Install XORP(To compile XORP requires nearly 1.4GB of free disk space)
Step 3.1: Download xorp-1.6.tar.gz
Step 3.2: untar the xorp-1.6.tar.gz
Step 3.3: ./configure
Step 3.4: make
Step 3.4-1: make check (just to check)(it is not necessary)

Step 4: run  rtrmgr/xorp_rtrmgr  rtrmgr/xorpsh (A sample xorp command shell)
Step 4.1: create user group named “xorp”

sudo addgroup xorp

Step 4.2: cp or edit config.boot in xorp-1.6/rtrmgr/config.boot
config.boot for our environment

protocols {
fib2mrib {
disable: false
}
igmp {
disable: false
interface eth0 {
vif eth0 {
disable: false
version: 3
enable-ip-router-alert-option-check: false
query-interval: 125
query-last-member-interval: 1
query-response-interval: 10
robust-count: 2
}
}
}
}
fea {
unicast-forwarding4 {
disable: false
}
}
interfaces {
restore-original-config-on-shutdown: false
interface eth0 {
disable: false
discard: false
description: “”
default-system-config {
}
}
}

Step 4.3: xorp-1.6/rtrmgr/xorp_rtrmgr -b xorp-1.6/rtrmgr/config.boot

Step 5: Check Mrouter work OK
Step 5.1: Connect eth0 to VLC Player server PC and connect eth1 to VLC Player client PC
Step 5.2: Use VLC Player server PC run multicast streaming
Step 5.3: Use VLC Player client PC to play multicast streaming by multicast URL

Step6: run rtrmgr/xorpsh (A sample xorp command shell)

xorp-1.6$ rtrmgr/xorpsh
Welcome to XORP on wifihack

border@wifihack> show igmp ?
Possible completions:
group                Display information about IGMP group membership
interface            Display information about IGMP interfaces

border@wifihack> show igmp group
Interface    Group           Source          LastReported Timeout V State
eth0         224.0.0.2       0.0.0.0         192.168.1.134     240 3     E
eth0         224.0.0.22      0.0.0.0         192.168.1.134     240 3     E
eth0         224.0.0.251     0.0.0.0         192.168.1.134     232 3     E
eth0         224.0.0.252     0.0.0.0         192.168.1.30     232 3     E
eth0         239.255.255.250 0.0.0.0         192.168.1.104     240 3     E

参考:
1. http://www.linuxdiyf.com/bbs/redirect.php?fid=55&tid=69157&goto=nextnewset
2. http://www.xorp.org/getting_started.html
3. “User Manual” http://www.xorp.org/releases/current/docs/user_manual/user_manual.pdf
4. http://en.wikipedia.org/wiki/XORP
5. http://en.wikipedia.org/wiki/IGMP

进来在作IGMP协议栈的解析，简单记录如下:

IGMPV3 Types

   There are two IGMP message types of concern to the IGMPv3 protocol
   described in this document:

      Type Number (hex)   Message Name
      -----------------   ------------

            0x11          Membership Query

            0x22          Version 3 Membership Report

   An implementation of IGMPv3 MUST also support the following three
   message types, for interoperation with previous versions of IGMP (see
   section 7):

           0x12          Version 1 Membership Report    [RFC-1112]

           0x16          Version 2 Membership Report    [RFC-2236]

IGMP V1 Query:

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |Version| Type  |    Unused     |           Checksum            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                         Group Address                         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

IGMP V2 Query:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      Type     | Max Resp Time |           Checksum            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                         Group Address                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

IGMP V3 Membership Query Message: :

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  Type = 0x11  | Max Resp Code |           Checksum            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                         Group Address                         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Resv  |S| QRV |     QQIC      |     Number of Sources (N)     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                       Source Address [1]                      |
      +-                                                             -+
      |                       Source Address [2]                      |
      +-                              .                              -+
      .                               .                               .
      .                               .                               .
      +-                                                             -+
      |                       Source Address [N]                      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

 Version 3 Membership Report Message

   Version 3 Membership Reports are sent by IP systems to report (to
   neighboring routers) the current multicast reception state, or
   changes in the multicast reception state, of their interfaces.
   Reports have the following format:

RFC 3376                         IGMPv3                     October 2002

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  Type = 0x22  |    Reserved   |           Checksum            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |           Reserved            |  Number of Group Records (M)  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      .                                                               .
      .                        Group Record [1]                       .
      .                                                               .
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      .                                                               .
      .                        Group Record [2]                       .
      .                                                               .
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                               .                               |
      .                               .                               .
      |                               .                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      .                                                               .
      .                        Group Record [M]                       .
      .                                                               .
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   where each Group Record has the following internal format:

      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |  Record Type  |  Aux Data Len |     Number of Sources (N)     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                       Multicast Address                       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                       Source Address [1]                      |
      +-                                                             -+
      |                       Source Address [2]                      |
      +-                                                             -+
      .                               .                               .
      .                               .                               .
      .                               .                               .
      +-                                                             -+
      |                       Source Address [N]                      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      .                                                               .
      .                         Auxiliary Data                        .
      .                                                               .
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Example:
Version 3 Membership Report Message
 22 00 ea 03     | Type: 22, Checksum: ea 03
 00 00 00 01     | Number of group recode 01
 04 00 00 00     | Recode type: 04, Number of Sources: 00 00
 ef ff ff fa      | Multicast Addr: 239.255.255.250

 Group Record Types

   There are a number of different types of Group Records that may be
   included in a Report message:

   o A "Current-State Record" is sent by a system in response to a Query
     received on an interface.  It reports the current reception state
     of that interface, with respect to a single multicast address.  The
     Record Type of a Current-State Record may be one of the following
     two values:

        Value  Name and Meaning
        -----  ----------------

          1    MODE_IS_INCLUDE - indicates that the interface has a
               filter mode of INCLUDE for the specified multicast
               address.  The Source Address [i] fields in this Group
               Record contain the interface's source list for the
               specified multicast address, if it is non-empty.

          2    MODE_IS_EXCLUDE - indicates that the interface has a
               filter mode of EXCLUDE for the specified multicast
               address.  The Source Address [i] fields in this Group
               Record contain the interface's source list for the
               specified multicast address, if it is non-empty.

   o A "Filter-Mode-Change Record" is sent by a system whenever a local
     invocation of IPMulticastListen causes a change of the filter mode
     (i.e., a change from INCLUDE to EXCLUDE, or from EXCLUDE to
     INCLUDE), of the interface-level state entry for a particular
     multicast address.  The Record is included in a Report sent from
     the interface on which the change occurred.  The Record Type of a
     Filter-Mode-Change Record may be one of the following two values:

          3    CHANGE_TO_INCLUDE_MODE - indicates that the interface
               has changed to INCLUDE filter mode for the specified
               multicast address.  The Source Address [i] fields
               in this Group Record contain the interface's new
               source list for the specified multicast address,
               if it is non-empty.

          4    CHANGE_TO_EXCLUDE_MODE - indicates that the interface
               has changed to EXCLUDE filter mode for the specified
               multicast address.  The Source Address [i] fields
               in this Group Record contain the interface's new
               source list for the specified multicast address,
               if it is non-empty.

   o A "Source-List-Change Record" is sent by a system whenever a local
     invocation of IPMulticastListen causes a change of source list that
     is *not* coincident with a change of filter mode, of the
     interface-level state entry for a particular multicast address.
     The Record is included in a Report sent from the interface on which
     the change occurred.  The Record Type of a Source-List-Change
     Record may be one of the following two values:

          5    ALLOW_NEW_SOURCES - indicates that the Source Address
               [i] fields in this Group Record contain a list of the
               additional sources that the system wishes to
               hear from, for packets sent to the specified
               multicast address.  If the change was to an INCLUDE
               source list, these are the addresses that were added
               to the list; if the change was to an EXCLUDE source
               list, these are the addresses that were deleted from
               the list.

          6    BLOCK_OLD_SOURCES - indicates that the Source Address
               [i] fields in this Group Record contain a list of the
               sources that the system no longer wishes to
               hear from, for packets sent to the specified
               multicast address.  If the change was to an INCLUDE
               source list, these are the addresses that were
               deleted from  the list; if the change was to an
               EXCLUDE source list, these are the addresses that
               were added to the list.

   If a change of source list results in both allowing new sources and
   blocking old sources, then two Group Records are sent for the same
   multicast address, one of type ALLOW_NEW_SOURCES and one of type
   BLOCK_OLD_SOURCES.

IGMP Query



IGMP Report



图来自  Linux Networking Architecture 17.3.4 Implementing IGMP

参考:
1. IGMPV1 rfc1112
2. IGMPV2 rfc2236
3. IGMPV3 rfc3376
4. Linux下IGMP以及多播路由分析
5. Design and Implementation of IGMPv3 for Linux (2000)  
6. Linux Kernel 2.6.26
7. 在线查看Kernel: http://lxr.linux.no/linux+v2.6.26/
8.  RFC3376 因特网组管理协议 第3版(译)
9.  Linux Networking Architecture (Chapter 17. IP Multicast for Group Communication)
10. Mapping IP Multicast to MAC-Layer Multicast