ssl_options.h File Reference

Transport-layer SSL/TLS configuration for VLink communication backends. More...

#include <string>
#include "../base/macros.h"
#include "./conf.h"

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Classes
struct	vlink::SslOptions
	Aggregate of SSL/TLS settings for transport-layer encryption. More...

Namespaces
namespace	vlink

Detailed Description

Transport-layer SSL/TLS configuration for VLink communication backends.

SslOptions provides a backend-agnostic way to configure transport-layer TLS encryption. It works through the ssl.* property convention that every transport backend reads during connection setup:

Backend	Native TLS Mechanism
MQTT	MQTTClient_SSLOptions (Paho C), auto tcp:// to ssl://
DDS	TCPv4TransportDescriptor::tls_config (Fast-DDS)
CycloneDDS	ddsi_config ssl fields (requires DDS_HAS_SSL)
Zenoh	transport/link/tls config keys (zenoh-c, not zenoh-pico)

Property Keys

Property Key	SslOptions Field	Description
ssl.ca	ca_file	CA certificate file path (PEM)
ssl.cert	cert_file	Client certificate file path (PEM)
ssl.key	key_file	Client private key file path (PEM)
ssl.key_password	key_password	Private key passphrase
ssl.verify	verify_peer	"0" to skip verification; default verify
ssl.server_name	server_name	SNI server name override
ssl.ciphers	ciphers	Cipher suite string (OpenSSL format)

Environment Variable Defaults

When a property is not set explicitly, the factory reads these environment variables as lowest-priority defaults (property values always take precedence):

Environment Variable	Maps to
VLINK_SSL_CA	ssl.ca
VLINK_SSL_CERT	ssl.cert
VLINK_SSL_KEY	ssl.key
VLINK_SSL_KEY_PASS	ssl.key_password
VLINK_SSL_VERIFY	ssl.verify
VLINK_SSL_SNI	ssl.server_name
VLINK_SSL_CIPHERS	ssl.ciphers

Auto-detection

SSL is considered valid (enabled) when ca_file or cert_file is non-empty. There is no separate ssl.enabled flag. When SSL is enabled on DDS/CycloneDDS, TCP transport is automatically activated because TLS requires TCP.

Usage

// --- Via Node API ---
Publisher<MyMsg> pub("mqtt://sensor/data");
SslOptions ssl;
ssl.ca_file   = "/etc/certs/ca.pem";
ssl.cert_file = "/etc/certs/client.pem";
ssl.key_file  = "/etc/certs/client-key.pem";
pub.set_ssl_options(ssl);
 
// --- Via set_property ---
pub.set_property("ssl.ca", "/etc/certs/ca.pem");
 
// --- Via global property ---
MqttConf::set_global_property("ssl.ca", "/etc/certs/ca.pem");
 
// --- Via environment variable ---
// export VLINK_SSL_CA=/etc/certs/ca.pem

Note

• Zenoh-pico (VLINK_ENABLE_ZENOH_PICO) does not support TLS; a warning is logged if SSL properties are present.
• CycloneDDS requires DDS_HAS_SSL at compile time; a warning is logged if SSL properties are present but the feature was not compiled in.