ssl_options.h File Reference

Backend-neutral SSL / TLS settings shared by all VLink transports that support encryption. 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
	vlink

Detailed Description

Backend-neutral SSL / TLS settings shared by all VLink transports that support encryption.

This is an internal implementation header used by NodeImpl and by every transport backend that supports TLS; user code typically interacts with SslOptions through Node::set_ssl_options(). The struct is a thin aggregate that the transport factory translates into the ssl.* property convention used during connection setup.

Native mechanism per backend

Backend	Underlying TLS mechanism
MQTT	MQTTClient_SSLOptions (Paho C); auto promotes 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)

SSL options table

Field	Property key	Description
ca_file	ssl.ca	CA certificate file path (PEM).
cert_file	ssl.cert	Client certificate file path (PEM).
key_file	ssl.key	Client private key file path (PEM).
key_password	ssl.key_password	Passphrase for an encrypted private key.
verify_peer	ssl.verify	"0" to skip server verification.
server_name	ssl.server_name	SNI override.
ciphers	ssl.ciphers	Cipher suite string (OpenSSL format).

Environment variable defaults

The factory consults these variables when the matching property is not set; explicit properties always win.

Environment variable	Property key
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

TLS is considered active when ca_file or cert_file is non-empty; there is no separate enable flag. On DDS / CycloneDDS, activating TLS also forces the TCP transport because TLS rides over TCP.

Example

// --- Through the public Node API ---
vlink::Publisher<MyMsg> pub("mqtt://sensor/data");
vlink::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);
 
// --- Through set_property ---
pub.set_property("ssl.ca", "/etc/certs/ca.pem");
 
// --- Through global property ---
vlink::MqttConf::set_global_property("ssl.ca", "/etc/certs/ca.pem");
 
// --- Through environment ---
// export VLINK_SSL_CA=/etc/certs/ca.pem

Note

• Zenoh-pico (VLINK_ENABLE_ZENOH_PICO) does not support TLS; SSL properties trigger a warning.
• CycloneDDS requires DDS_HAS_SSL at compile time; if the feature was not compiled in, SSL properties also trigger a warning.