On Tue, 6 Feb 2001, Bing Zhang wrote:
> I have a buffer below. Could someone tell me how they decoded the
> extension additions using PER?
> I mean that from "conferenceID" , how can I know only
> "callIdentifier" is present and other optional such as
> "h245SecurityMode", "tokens","cryptoTokens","fastStart" are absent?
> since Hex "09 00 11 00" is between "conferenceID" and
> "callIdentifier", what are these Hex"09 00 11 00" doing there?
The 09 00 11 00 is broken down in bits as follows:
0000 100 indicates that the number of extensions present is the
ASN.1 type definition is 5
1000 0 indicates that only the first extension addition value is
present in the encoding
0000 pad bits to align length field on word boundary
0001 0001 length of extension addition value is 17
Start of encoded extension addition value:
0 CallerIdentifier has no extension addition values present
000 0000 pad bits to align GloballyUniqueID value to octet boundary
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> Connect-UUIE is defined in H225 specification.
> Connect-UUIE ::= SEQUENCE
> {
> protocolIdentifier ProtocolIdentifier,
> h245Address TransportAddress OPTIONAL,
> destinationInfo EndpointType,
> conferenceID ConferenceIdentifier,
> ...,
> callIdentifier CallIdentifier,
> h245SecurityMode H245Security OPTIONAL,
> tokens SEQUENCE OF ClearToken OPTIONAL,
> cryptoTokens SEQUENCE OF CryptoH323Token OPTIONAL,
> fastStart SEQUENCE OF OCTET STRING OPTIONAL
> }
>
> Below is ASN.1 decoding for Connect-UUIE
> ASN.1: value H323-UserInformation ::=
> ASN.1: {
> ASN.1: h323-uu-pdu
> ASN.1: {
> ASN.1: h323-message-body connect :
> ASN.1: {
> ASN.1: protocolIdentifier { 0 0 8 2250 0 2 },
> ASN.1: h245Address ipAddress :
> ASN.1: {
> ASN.1: ip 'C0A80196'H,
> ASN.1: port 1037
> ASN.1: },
> ASN.1: destinationInfo
> ASN.1: {
> ASN.1: vendor
> ASN.1: {
> ASN.1: vendor
> ASN.1: {
> ASN.1: t35CountryCode 181,
> ASN.1: t35Extension 0,
> ASN.1: manufacturerCode 21324
> ASN.1: },
> ASN.1: productId
>'4D6963726F736F6674AE204E65744D656574696E67AE00'H,
> ASN.1: versionId '332E3000'H
> ASN.1: },
> ASN.1: terminal
> ASN.1: {
> ASN.1: },
> ASN.1: mc FALSE,
> ASN.1: undefinedNode FALSE
> ASN.1: },
> ASN.1: conferenceID 'DC3164503C21D41180CE00C04FA0C74A'H,
>//Question???????????????????????
> ASN.1: callIdentifier
> // Question????????????????????????
> ASN.1: {
> ASN.1: guid 'DB3164503C21D41180CE00C04FA0C74A'H
> ASN.1: }
> ASN.1: }
> ASN.1: }
> ASN.1: }
>
> Here is the Hex
> 02 C0 06 00 08 91 4A 00 02 00 C0 A8 01 96 04 0D
> 22 C0 B5 00 53 4C 16 4D 69 63 72 6F 73 6F 66 74
> AE 20 4E 65 74 4D 65 65 74 69 6E 67 AE 00 03 33
> 2E 30 00 00 DC 31 64 50 3C 21 D4 11 80 CE 00 C0
> 4F A0 C7 4A 09 00 11 00 DB 31 64 50 3C 21 D4 11
> 80 CE 00 00 C0 4F A0 C7 4A
>
> Thanks
>
>
>
