Cellular Test Library for Mbed CE

Driver-agnostic connectivity probes (UDP, TCP, TLS, DTLS, HTTP, HTTPS) for cellular modems under Mbed CE.

Overview

Compile-time procedure selection - only the chosen test is built, so flash footprint stays small. Works with any NetworkInterface; supports native Mbed TLS or modem-offloaded TLS/DTLS.

Set cellular-test.test-procedure in mbed_app.json5:

Value	Procedure
0	UDP echo
1	TCP echo
2	TLS echo, native Mbed TLS
3	TLS echo, modem offload (fwTLS)
4	DTLS echo, native Mbed TLS
5	DTLS echo, modem offload (fwDTLS)
6	HTTP GET
7	HTTPS GET

Offload procedures (3, 5) require nsapi.offload-tlssocket=true and a modem driver that honours the NSAPI_TLSSOCKET_* setsockopt contract. Set tls-security-profile to the modem profile ID provisioned with the CA.

Integration

Add the library and wire it up:

add_subdirectory(cellular_test)
target_link_libraries(your_app_target cellular-test)

#include "cellular_test.h"

int main() {
    NetworkInterface *net = CellularInterface::get_default_instance();
    cellular_test::ITest *test = cellular_test::create_test(*net);
    if (test) {
        test->run();
        test->print_results();
    }
}

For TLS/DTLS/HTTPS, supply certificates before run() via TlsServerConfig / DtlsServerConfig / HttpServerConfig - use create_tls_test() / create_dtls_test() / create_http_test() to inject them.

Configuration

All keys live under the cellular-test namespace in mbed_lib.json.

Endpoints

Option	Default	Notes
udp-echo-server-hostname	"echo.example.com"	Procedure 0
udp-echo-server-ip	"0.0.0.0"	Used when use-direct-ip=true
udp-echo-server-port	7
tcp-echo-server-hostname	"echo.example.com"	Procedure 1
tcp-echo-server-ip	"0.0.0.0"
tcp-echo-server-port	7
tls-echo-server-hostname	"echo.example.com"	Procedures 2–5 (DNS + SNI)
tls-echo-server-ip	"0.0.0.0"
tls-echo-server-port	443
dtls-echo-server-port	5684
http-server-hostname	"httpbin.org"	Procedures 6–7
http-server-ip	"0.0.0.0"
http-server-port	80
https-server-port	443
http-path	"/get"

Behaviour

Option	Default	Notes
use-direct-ip	false	Skip DNS. Hostname is still used for SNI.
ping-pong-cycles	5	Echo iterations
test-payload	"HELLO_NBIOT"	Echo payload
tls-security-profile	0	Modem profile ID (offload only, 0–15)
cert-verify-mode	0	Native TLS/DTLS: 0=REQUIRED, 1=OPTIONAL, 2=NONE (debug only)
socket-timeout-ms	15000	Data exchange timeout
tls-handshake-timeout-ms	60000	TLS/DTLS handshake timeout
connect-retry-count	3	Network connect retries

cert-verify-mode can also be overridden per-test at runtime by setting TlsServerConfig::cert_verify_mode / DtlsServerConfig::cert_verify_mode before run(). Never ship with mode 2 (VERIFY_NONE) - it disables server authentication entirely.

Layout

cellular_test/
├── CMakeLists.txt
├── mbed_lib.json
├── include/
│   ├── cellular_test.h                 # Public entry point + factory
│   └── cellular_test/
│       ├── ITest.h                     # Test interface
│       ├── TestConfig.h                # *ServerConfig structs
│       ├── TestProcedure.h             # CELLULAR_TEST_IS_* macros
│       ├── TestResults.h, TestTimer.h, TestPrint.h
│       ├── NetworkTestHelper.h         # Connect / DNS / retry helper
│       └── EchoTest.h, TlsTest.h, DtlsTest.h, HttpTest.h
└── src/
    ├── NetworkTestHelper.cpp
    └── EchoTest.cpp, TlsTest.cpp, DtlsTest.cpp, HttpTest.cpp

Related projects

• iot-test-service: Docker testbed exposing the UDP / TCP / TLS / DTLS / HTTP / HTTPS endpoints this library drives, plus a .NET management API for run metadata.
• mbed-ce-bc660kgl-app: Quectel BC660K-GL EVKIT app using this library.
• mbed-ce-bg770agl-app: Quectel BG770A-GL EVKIT app using this library.
• mbed-ce-st87m01-app: ST ST87M01-1 EVKIT app using this library.

License

Apache License 2.0. See LICENSE.