smpp-js/interop-tests/README.md

interop-tests

Eight real SMPP implementations, run against this library in both directions, with every session decoded independently by tshark so no result rests on our own view of the wire. It exists because the unit suite and this library's own dummy peers agree with themselves; these peers do not.

It ran between 2026-09-05 and 2026-09-08 and found twelve defects, all fixed. This file replaces PLAN.md, which the findings below still cite by name.

AGENTS.md is how a run works: the layout, run.py, what the capture must show, and the rules an experiment follows.

What it found

Peer	Findings
ukarim/smscsim	01-smscsim.md
SMPPSim	02-smppsim.md
Jasmin	03-jasmin.md
Kannel	04-kannel.md
jsmpp, Cloudhopper	05-java-clients.md
python-smpplib, php-smpp	06-python-php.md
smppload, smpp-dumb-client	07-load.md
Operator documentation, as fixtures	09-operator-fixtures.md

Each records what the peer does on the wire, every defect with a reproducer, and the peer's own quirks — several findings are the peer's bug, not ours, and say so.

Peers

Our client binds to these:

Peer	What it is for	Run
Jasmin 0.11.0	A production gateway with an independent codec, SAR segmentation, UUID ids, and a DLR pipeline that can use data_sm	jookies/jasmin:0.11.0 + redis:8.8.2-alpine + rabbitmq:3.13.7-management-alpine, bootstrapped over jcli by peers/jasmin/bootstrap.py
SMPPSim 2.6.11	The richest fault injection available: per-state receipt percentages, delayed and intermediate receipts, queue-full, loopback, SMSC-initiated outbind, receipts with or without TLVs	Built from kwahome/smpp-sim-docker; nine .props variants under peers/smppsim/
ukarim/smscsim 0.2.0	Zero setup and MO injection from a web page — the smoke test that proves the harness	ukarim/smscsim:0.2.0. No PDU validation, so it proves nothing about strictness

These bind to our server:

Peer	What it is for	Run
Kannel 1.4.5	The most deployed real ESME there is; parses our receipts with the parser most operators' customers run, and declares 3.4 or 3.3 on demand	debian:bookworm-slim + the distribution package; four .conf variants under peers/kannel/
jsmpp	Strict and low-level: the driver builds UDH, sar_* and message_payload bytes by hand, and rejects an answer it dislikes	Maven build at a pinned commit, peers/jsmpp/
Cloudhopper	The one peer with real windowing knobs, plus a TLS client	Maven build at a pinned commit, peers/cloudhopper/. Its 2015-era TLS client cannot do 1.3, so that scenario caps the server at 1.2
python-smpplib 2.2.4	An independent GSM 03.38 table to cross-check ours character by character	python:3.12.14-slim-bookworm, peers/python/
php-smpp	Three long-message spellings from one client, and separate transmitter and receiver binds	php:8.4.25-cli at a pinned commit, peers/php/. Its socket guard uses a check PHP 8 broke, so the image patches it
smpp-dumb-client	A genuinely enforced bounded window, which is what tests backpressure rather than raw rate	Go build at a pinned commit, peers/dumbclient/
smppload	Intended for throughput; its own bind_transceiver is two octets shorter than it declares, so it never binds. Kept as a live reproducer that our server refuses the stream rather than hanging	Erlang build, peers/smppload/

Scenario ids

The findings cite these. fixture means a raw-socket peer in our own suite, because no open implementation emits that shape on demand.

#	Scenario	Peers
C1	Bind each type, enquire_link both ways, unbind	all SMSC peers
C2	Text-only receipts, no TLVs	SMPPSim
C3	Receipts with receipted_message_id and message_state	Jasmin, SMPPSim
C4	Intermediate then final receipt	SMPPSim
C5	Failure states, and the worst segment winning a merge	SMPPSim
C6	A receipt delayed past a link drop	SMPPSim
C7	Long MT in GSM and UCS-2, 2, 3 and 10 segments	SMPPSim, Jasmin
C8	Long MO as UDH 8-bit, UDH 16-bit, sar_* and message_payload	Jasmin, jsmpp, SMPPSim
C9	MO or receipt on data_sm	Jasmin
C10	Unknown command id, malformed and vendor TLVs	fixture, jsmpp
C11	Bind refused, and the backoff that must not flood	Jasmin, SMPPSim, a closed port
C12	Throttling and queue-full on submit	Jasmin, SMPPSim, smscsim
C13	A slow SMSC and a full window	Jasmin, SMPPSim
C14	TLS against a public certificate authority	not run — see Untested
C15	interfaceVersion 0x50, and a peer answering 3.3 or nothing	SMPPSim, fixture
C16	Receipt text variants from operator documentation	fixture
C17	Encodings round trip	SMPPSim
C18	outbind from the SMSC	SMPPSim
S1	Kannel at "34" and at "33", submitting, receipts, MO	Kannel
S2	Long messages in every spelling to our server	jsmpp, php-smpp, python-smpplib
S3	Unhandled and unknown commands, and whether a strict client accepts our answers	jsmpp
S4	Separate transmitter and receiver binds	php-smpp
S5	Window pressure against a slow listener	Cloudhopper
S6	A peer that never sends a keepalive	smpp-dumb-client
S7	A production gateway as the ESME, parsing our receipts	Jasmin
S8	Throughput, with receipts and long messages	smppload — blocked, see above
S9	A bounded window under load	smpp-dumb-client
S10	TLS from a Java client	Cloudhopper
S11	Encodings from another implementation's encoder	python-smpplib

Untested

Three things this suite never exercised. None is a known defect; each is a claim resting on the specification and on Node rather than on a peer having agreed.

• A TLS handshake against a certificate a public authority signed. Every TLS test here uses a certificate generated for the test, so what is proven is that the handshake works and that a bad certificate is refused. Verifying a real chain is Node's job and we pass tls.ConnectionOptions through untouched, which is why this is a thin risk rather than none.
• A peer that genuinely speaks SMPP 5.0. interfaceVersion: 0x50 is tested against peers that answer 3.4 or answer nothing, so what 5.0 declares back is unobserved.
• An SMSC written by someone who never sees this code. Every peer here is open source and configured by us. A closed commercial SMSC is the one thing a free suite cannot buy, and the first operator integration is where that gets answered.

The research behind the peer choices and the operator quirks, one source URL per claim, is in research/. Ask before trusting a claim there that a peer's own docs would settle.