go-sccp

go-sccp is a Go implementation of SCCP, the Signalling Connection Control Part used in SS7 and SIGTRAN stacks.

The package currently provides complete ITU-T Q.713 message and parameter encoding/decoding, plus the first Q.714 connection-section procedure helpers. It is suitable for building, parsing, validating, and testing SCCP wire messages while the full procedure stack is being completed.

Status

This module is pre-v1. Public APIs may still change while the Q.714 procedure layer is completed.

Implemented:

• ITU-T Q.713 (03/01) message codecs for all SCCP message types.
• ITU-T Q.713 (03/01) parameter codecs for the full standard parameter set.
• Strict parser coverage for short buffers and malformed optional parameter lengths.
• Fuzz targets for top-level message parsing and parameter parsing.
• Initial ITU-T Q.714 (05/01) connection-section helpers for CC/CREF setup outcomes, RLSD/RLC release handling, reference mismatch detection, frozen reference state, class 2 DT1 data transfer, and class 3 DT2/AK sequence and flow-control windows.
• In-memory SCCP stack core for local subsystem registration, connectionless N-UNITDATA delivery, UDTS/XUDTS/LUDTS return generation, N-NOTICE delivery, and connection-oriented section lifecycle orchestration.
• CI for build, tests, race tests, vet, static analysis, vulnerability checks, portability, and security scanning.

Remaining stack work:

• Q.714 global title translation, relay routing, compatibility tests, message type changes, segmentation, reassembly, and management procedure integration.
• Q.714 freeze/guard timers and relay coupling for multi-section connections.
• Q.714 class 3 reset, expedited data, inactivity testing, and timer behavior.
• Q.714 connection-oriented segmentation/reassembly across multiple DT messages.

See docs/standards.md for the standards baseline, errata policy, open-source survey, and detailed compliance ledger.

Install

go get github.com/gomaja/go-sccp

Message Encoding

package main

import (
	"log"

	"github.com/gomaja/go-sccp"
	"github.com/gomaja/go-sccp/params"
)

func main() {
	msg := sccp.NewUDT(
		0,
		true,
		params.NewCalledPartyAddress(0x42, 0, 6, nil),
		params.NewCallingPartyAddress(0x42, 0, 7, nil),
		[]byte("payload"),
	)

	wire, err := msg.MarshalBinary()
	if err != nil {
		log.Fatal(err)
	}

	log.Printf("%x", wire)
}

Message Parsing

package main

import (
	"log"

	"github.com/gomaja/go-sccp"
)

func main() {
	msg, err := sccp.ParseMessage([]byte{
		0x09, 0x80, 0x03, 0x06, 0x09,
		0x02, 0x42, 0x06,
		0x02, 0x42, 0x07,
		0x07, 'p', 'a', 'y', 'l', 'o', 'a', 'd',
	})
	if err != nil {
		log.Fatal(err)
	}

	log.Printf("%s", msg.MessageTypeName())
}

Connection-Section Procedures

package main

import (
	"log"

	"github.com/gomaja/go-sccp"
	"github.com/gomaja/go-sccp/params"
)

func main() {
	section := sccp.NewPendingConnectionSection(0x010203, 3, 8)

	confirm := sccp.NewCC(0x010203, 0x040506, 2, false)
	if err := section.HandleConnectionConfirm(confirm); err != nil {
		log.Fatal(err)
	}

	released, err := section.Release(params.ReleaseCauseSCCPUserOriginated)
	if err != nil {
		log.Fatal(err)
	}

	log.Printf("%s to %06x", released.MessageTypeName(), released.DestinationLocalReference.Uint32())
}

Supported Messages

Message type	Abbreviation	Reference	Codec
Connection request	CR	ITU-T Q.713 (03/01) 4.2	Yes
Connection confirm	CC	ITU-T Q.713 (03/01) 4.3	Yes
Connection refused	CREF	ITU-T Q.713 (03/01) 4.4	Yes
Released	RLSD	ITU-T Q.713 (03/01) 4.5	Yes
Release complete	RLC	ITU-T Q.713 (03/01) 4.6	Yes
Data form 1	DT1	ITU-T Q.713 (03/01) 4.7	Yes
Data form 2	DT2	ITU-T Q.713 (03/01) 4.8	Yes
Data acknowledgement	AK	ITU-T Q.713 (03/01) 4.9	Yes
Unitdata	UDT	ITU-T Q.713 (03/01) 4.10	Yes
Unitdata service	UDTS	ITU-T Q.713 (03/01) 4.11	Yes
Expedited data	ED	ITU-T Q.713 (03/01) 4.12	Yes
Expedited data acknowledgement	EA	ITU-T Q.713 (03/01) 4.13	Yes
Reset request	RSR	ITU-T Q.713 (03/01) 4.14	Yes
Reset confirm	RSC	ITU-T Q.713 (03/01) 4.15	Yes
Protocol data unit error	ERR	ITU-T Q.713 (03/01) 4.16	Yes
Inactivity test	IT	ITU-T Q.713 (03/01) 4.17	Yes
Extended unitdata	XUDT	ITU-T Q.713 (03/01) 4.18	Yes
Extended unitdata service	XUDTS	ITU-T Q.713 (03/01) 4.19	Yes
Long unitdata	LUDT	ITU-T Q.713 (03/01) 4.20	Yes
Long unitdata service	LUDTS	ITU-T Q.713 (03/01) 4.21	Yes

Supported Parameters

Parameter name	Reference	Codec
End of optional parameters	ITU-T Q.713 (03/01) 3.1	Yes
Destination local reference	ITU-T Q.713 (03/01) 3.2	Yes
Source local reference	ITU-T Q.713 (03/01) 3.3	Yes
Called party address	ITU-T Q.713 (03/01) 3.4	Yes
Calling party address	ITU-T Q.713 (03/01) 3.5	Yes
Protocol class	ITU-T Q.713 (03/01) 3.6	Yes
Segmenting/reassembling	ITU-T Q.713 (03/01) 3.7	Yes
Receive sequence number	ITU-T Q.713 (03/01) 3.8	Yes
Sequencing/segmenting	ITU-T Q.713 (03/01) 3.9	Yes
Credit	ITU-T Q.713 (03/01) 3.10	Yes
Release cause	ITU-T Q.713 (03/01) 3.11	Yes
Return cause	ITU-T Q.713 (03/01) 3.12	Yes
Reset cause	ITU-T Q.713 (03/01) 3.13	Yes
Error cause	ITU-T Q.713 (03/01) 3.14	Yes
Refusal cause	ITU-T Q.713 (03/01) 3.15	Yes
Data	ITU-T Q.713 (03/01) 3.16	Yes
Segmentation	ITU-T Q.713 (03/01) 3.17	Yes
Hop counter	ITU-T Q.713 (03/01) 3.18	Yes
Importance	ITU-T Q.713 (03/01) 3.19	Yes
Long data	ITU-T Q.713 (03/01) 3.20	Yes

Validation

The local validation target for Go changes is:

go build ./...
go test ./... -count=1
go vet ./...
~/go/bin/staticcheck ./...
~/go/bin/golangci-lint run ./...

Protocol changes should also run race tests and the relevant fuzz targets.

License

MIT. See LICENSE.