go-tcap

Simple TCAP implementation in Golang

Package tcap provides simple and painless handling of TCAP(Transaction Capabilities Application Part) in SS7/SIGTRAN protocol stack, implemented in the Go Programming Language.

Though TCAP is ASN.1-based protocol, this implementation does not use any ASN.1 parser. That makes this implementation flexible enough to create arbitrary payload with any combinations, which is useful for testing.

Disclaimer

This is still an experimental project, and currently in its very early stage of development. Any part of implementations(including exported APIs) may be changed before released as v1.0.0.

Getting started

Prerequisites

go-gtp supports Go Modules. Just run go mod tidy in your project's directory to collect the required packages automatically.

go mod tidy

This project follows the Release Policy of Go.

Running examples

A sample client is available in examples/client/, which, by default, establishes SCTP/M3UA connection with a server sends a MAP cancelLocation.

Transaction Capabilities Application Part
    begin
        [Transaction Id: 11111111]
        Source Transaction ID
        oid: 0.0.17.773.1.1.1 (id-as-dialogue)
        dialogueRequest
        components: 1 item
            Component: invoke (1)
                invoke
                    invokeID: 0
                    opCode: localValue (0)
                    CONSTRUCTOR
                        CONSTRUCTOR Tag
                        Tag: 0x00
                        Length: 10
                        Parameter (0x04)
                            Tag: 0x04
                            Length: 8
                        Data: 00
GSM Mobile Application
    Component: invoke (1)
        invoke
            invokeID: 0
            opCode: localValue (0)
                localValue: cancelLocation (3)
            identity: imsi-WithLMSI (1)
                imsi-WithLMSI
                    IMSI: 001010123456789
                    [Association IMSI: 001010123456789]

Some parameters can be speficied from command-line arguments. Other parameters including the ones in lower layers (such as Point Code in M3UA, Global Title in SCCP, etc.) should be updated by modifying the source code.

$ ./client -h
Usage of client:
  -addr string
        Remote IP and Port to connect to. (default "127.0.0.2:2905")
  -opcode int
        Operation Code in int. (default 3)
  -otid int
        Originating Transaction ID in uint32. (default 286331153)
  -payload string
        Hex representation of the payload (default "040800010121436587f9")

If you are looking for a server that just can accept a SCTP/M3UA connection to receive a TCAP packet, server example in go-m3ua project would be a nice choice for you.

Supported Features

Transaction Portion

Message Types

Message type	Supported?
Unidirectional
Begin	Yes
End	Yes
Continue	Yes
Abort	Yes

Fields

Tag	Supported?
Originating Transaction ID	Yes
Destination Transaction ID	Yes
P-Abort Cause	Yes

Component Portion

Component types

Component type	Supported?
Invoke	Yes
Return Result (Last)	Yes
Return Result (Not Last)	Yes
Return Error	Yes
Reject	Yes

Dialogue Portion

Dialogue types

Dialogue type	Supported?
Dialogue Request (AARQ-apdu)	Yes
Dialogue Response (AARE-apdu)	Yes
Dialogue Abort (ABRT-apdu)	Yes
Unidirectional Dialogue (AUDT-apdu)

Elements

Tag	Type	Supported?
Object Identifier	Structured	Yes
Single-ASN.1-type	Structured	Yes
Dialogue PDU	Structured	Yes
Object Identifier	Unstructured
Single-ASN.1-type	Unstructured
Unidirectional Dialogue PDU	Unstructured

Author(s)

Yoshiyuki Kurauchi (Website / Twitter)

I'm always open to welcome co-authors! Please feel free to talk to me.

LICENSE

MIT