megaco decoding with opal

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Posts: 1
Joined: Wed Apr 11, 2012 9:06 am

megaco decoding with opal

Post by legyndir »

i all,

I am trying to decode H248 megaco messages using opal library. I convert the payload (bytes after udp header) to PPer_Stream and give that to H248Message::Decode() method, but I dont get any meaningful output.

Here's how I use it:

PPER_Stream pstr((const BYTE *) pl, pllen);
H248_Message msg;


version = 33
mId = domainName {
name = " []:2944 T=12449096{C=${A=T00100000003"
portNumber = 12338
messageBody = messageError {
errorCode = 12336

and payload starts like this:
"!/1 []:2944 T=12449096{C=${A=T0010000000302100005{E=12070391{......."

I also tried H248_MegacoMessage, but didnt help.

Any1 else tried decoding Megaco messages successfully?

Posts: 1
Joined: Tue May 22, 2012 8:48 am

Re: megaco decoding with opal

Post by nmozilla »

i have the same problem.
do you find any usefull answer to your question ?

Posts: 1
Joined: Tue Aug 14, 2012 2:27 am

Re: megaco decoding with opal

Post by hunters »


In default generation, all ASN object has UniversalTagClass. You must change tags and tag classes depend on the data you receive.

I'm having problem with decode CHOICE item.


ip4Address IP4Address,
ip6Address IP6Address,
domainName DomainName,
deviceName PathName,
mtpAddress OCTET STRING(SIZE(2)),
-- Addressing structure of mtpAddress:
-- 15 0
-- | PC | NI |
-- 14 bits 2 bits

IP4Address ::= SEQUENCE
address OCTET STRING (SIZE(4)),
portNumber INTEGER(0..65535) OPTIONAL

Then in the data, MID has own tag/type field, IP4Address has different tag/type field. But when decode, IP4Address gets tag/type of MID to make its own tag/type. It yields the address field in IP4Address has 10 octet string. OMG

Does anyone have the same problem?


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