python unpack缓冲区数据

Question

我rlm_python在半径中使用模块,它option82以十六进制或二进制格式从coovachilli 获取DHCP位置.

将其作为字符串捕获显示为此值\001\027\002\025\001+\001\024,但查看python显示的值被截断,因为option82包含suboptions 编码,TLVs-type,length,values其中字段以type开头0x01(circuit ID, per RFC 3046),后跟一个字节长度.

知道如何抓住这个并正确解开选项吗？

我一直在使用解压缩字符串struct.unpack,但不是meaningful..as它没有告诉有关包装suboptions的option82领域.

Python 2.4.3 (#1, May  5 2011, 16:39:10) 
[GCC 4.1.2 20080704 (Red Hat 4.1.2-50)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> from struct import *
>>> unpack('=hhl',"\001\027\002\025\001+\001\024" )
(5889, 5378, 335620865)

有任何想法吗？

更新:

Coovachilli是用编译的--locationopt82,它发送位置作为属性,像这样...

rad_recv: Accounting-Request packet from host 10.66.53.49 port 53178, id=101, length=342
        ChilliSpot-Version = "1.3.0"
        ChilliSpot-Acct-View-Point = ChilliSpot-Client-View-Point
        Event-Timestamp = "Apr 18 2013 11:59:16 BST"
        User-Name = "3C-D0-F8-4A-05-68"
        Acct-Input-Octets = 0
        Acct-Output-Octets = 22851
        Acct-Input-Gigawords = 0
        Acct-Output-Gigawords = 0
        Acct-Input-Packets = 0
        Acct-Output-Packets = 370
        Acct-Session-Time = 5401
        ChilliSpot-Session-State = Authorized
        Acct-Status-Type = Interim-Update
        Acct-Session-Id = "516fbceb00000002"
        Framed-IP-Address = 10.75.33.46
        NAS-Port-Type = Wireless-802.11
        NAS-Port = 2
        NAS-Port-Id = "00000002"
        Calling-Station-Id = "3C-D0-F8-4A-05-68"
        Called-Station-Id = "00-50-56-B7-66-00"
        NAS-IP-Address = 10.75.32.7
        ChilliSpot-Location = "\001\030\002\026\001+\001\024"
        ChilliSpot-Location-Change-Count = 15
        NAS-Identifier = "VLAN299-REGENT"
        WISPr-Location-ID = "isocc=GR,cc=44,ac=01200,network=mywifi,my_Network_regent"
        WISPr-Location-Name = "REGENT"

freeradius具有rlm_python查找记帐请求的模块

def accounting(p):
    file = open("/tmp/test.log","a")
    username = None
    chillilocation = None
    output = StringIO.StringIO()

    for t in p:
        if t[0] == 'User-Name':
            username = t[1]
        elif t[0] == 'ChilliSpot-Location':
            chillilocation = t[1]a
             output.write(t[1])


    content = output.getvalue()


    file.write("I am being called in radius accouting section as %s and location is %s \n" % (username,content))
    file.close()
    print "---Accounting---"
    radiusd.radlog(radiusd.L_INFO, '*** radlog call in accounting (0) ***')
    print
    print p
    return radiusd.RLM_MODULE_OK

我已经尝试将ChilliSpot-Location存储在string和中stringIO,使用struct解压缩但无济于事,它看起来像TLV格式......

任何想法如何剥离它？

Answer 1

Unpack 不会解压为“有意义”的值。它将字符串解包为数字字段序列，以便每个字段的大小由格式字符串的每个字符指定（字母前面的数字是乘数）。

解包不应该使用八位字节大小的字段吗？

>>> unpack('=8B',"\001\027\002\025\001+\001\024")
(1, 23, 2, 21, 1, 43, 1, 20)
# 或者也许 '+ ' 是分隔符 (43):
>>> unpack('=6Bh',"\001\027\002\025\001+\001\024")
(1, 23, 2, 21, 1, 43, 5121 ）

第一个字节可能是电路子选项代码 (unpack()[0]==1)，其大小奇怪地高为 23，这意味着我们没有获得整个子选项值。但我们也可能只有 size == 10 的子选项的包含值，或 8 个字节的内容。

我不太确定选项 82 是否应该包含可读字符串，尽管“ChilliSpot-Location”确实包含。RFC3046 指示电路子选项应包含“路由器接口号”、端口号和其他数值等内容。但是 rad_recv 的属性真的来自 82 选项吗？