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NAME

ppp_oe_tag_dissect - point-to-point over ethernet tag diissect function

SYNOPSIS

opn=ppp_oe_tag_dissect(pkt,offset,tag_end)

PPPOE_TAG_EOL = 0
PPPOE_TAG_SVC_NAME = 257
PPPOE_TAG_AC_NAME = 258
PPPOE_TAG_HOST_UNIQ = 259
PPPOE_TAG_AC_COOKIE = 260
PPPOE_TAG_VENDOR = 261
PPPOE_TAG_RELAY_ID = 272
PPPOE_TAG_SVC_ERR = 513
PPPOE_TAG_AC_ERR = 514
PPPOE_TAG_GENERIC_ERR = 515

DESCRIPTION

dissect point-to-point over ethernet tags.
prototype is:  
                      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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |          TAG_TYPE             |        TAG_LENGTH             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |          TAG_VALUE ...                                        ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                                                references RFC 2516

dissectable are:

end-of-list
service-name
ac-name
host-uniq
ac-cookie
vendor-specific
relay-session-id
service-name-error
ac-system-error
generic-error

funtion accepts three arguments:
    pkt is a packet reference containing the whole already dissected packet
    offset is the position inside packet to start dissection
    tag_end equals offset plus tag length

funtion returns one list:
    opn is a list
    each item of the list is a dissected tag
    this is the tag's prototype: [tag_code,tag_length,(tag_field1,tag_field2,.......,tag_fieldN)] 
    note: negative tag_code means tag exceeds global tags length