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.