Ensure we always startup with a rustls CryptoProvider

The `rustls` library recently introduced this weird behavior where they
expect users to, apart from configuring the respective feature, also
explictly call `CryptoProvider::install_default`. Otherwise they'd
simply panic at runtime whenever the first network call requiring TLS
would be made. While we already made a change upstream at
`rust-electrum-client`, we also make sure here that we definitely,
always, absolutley are sure that we have a `CryptoProvider` set on
startup.

Author: tnull

Cargo.toml

@@ -67,6 +67,7 @@ bdk_electrum = { version = "0.23.0", default-features = false, features = ["use-
 bdk_wallet = { version = "2.0.0", default-features = false, features = ["std", "keys-bip39"]}
 
 reqwest = { version = "0.12", default-features = false, features = ["json", "rustls-tls"] }
+rustls = { version = "0.23", default-features = false }
 rusqlite = { version = "0.31.0", features = ["bundled"] }
 bitcoin = "0.32.4"
 bip39 = "2.0.0"

src/builder.rs

@@ -74,7 +74,7 @@ use std::fmt;
 use std::fs;
 use std::path::PathBuf;
 use std::sync::atomic::AtomicBool;
-use std::sync::{Arc, Mutex, RwLock};
+use std::sync::{Arc, Mutex, Once, RwLock};
 use std::time::SystemTime;
 use vss_client::headers::{FixedHeaders, LnurlAuthToJwtProvider, VssHeaderProvider};
 
@@ -936,6 +936,8 @@ fn build_with_store_internal(
 	liquidity_source_config: Option<&LiquiditySourceConfig>, seed_bytes: [u8; 64],
 	logger: Arc<Logger>, kv_store: Arc<DynStore>,
 ) -> Result<Node, BuildError> {
+	optionally_install_rustls_cryptoprovider();
+
 	if let Err(err) = may_announce_channel(&config) {
 		if config.announcement_addresses.is_some() {
 			log_error!(logger, "Announcement addresses were set but some required configuration options for node announcement are missing: {}", err);
@@ -1525,6 +1527,27 @@ fn build_with_store_internal(
 	})
 }
 
+fn optionally_install_rustls_cryptoprovider() {
+	// Acquire a global Mutex, ensuring that only one process at a time install the provider. This
+	// is mostly required for running tests concurrently.
+	static INIT_CRYPTO: Once = Once::new();
+
+	INIT_CRYPTO.call_once(|| {
+		// Ensure we always install a `CryptoProvider` for `rustls` if it was somehow not previously installed by now.
+		if rustls::crypto::CryptoProvider::get_default().is_none() {
+			let _ = rustls::crypto::aws_lc_rs::default_provider()
+				.install_default()
+				.or(rustls::crypto::ring::default_provider().install_default());
+		}
+
+		// Refuse to startup without TLS support. Better to catch it now than even later at runtime.
+		assert!(
+			rustls::crypto::CryptoProvider::get_default().is_some(),
+			"We need to have a CryptoProvider"
+		);
+	});
+}
+
 /// Sets up the node logger.
 fn setup_logger(
 	log_writer_config: &Option<LogWriterConfig>, config: &Config,