citadel_sdk/builder/
node_builder.rs

1//! Node Builder API for Citadel Protocol
2//!
3//! This module provides a builder pattern interface for constructing and configuring Citadel network nodes.
4//! The builder supports creating both peer and server nodes with customizable settings for security,
5//! networking, and backend storage.
6//!
7//! # Features
8//! - Flexible node type configuration (Peer/Server)
9//! - Multiple backend storage options (In-memory, Filesystem, SQL with enterprise feature)
10//! - Customizable security settings (TLS, certificates)
11//! - Google services integration (optional)
12//! - STUN server configuration for NAT traversal
13//! - Server authentication via pre-shared keys
14//!
15//! # Example
16//! ```rust
17//! use citadel_sdk::prelude::*;
18//! use std::net::SocketAddr;
19//! use std::str::FromStr;
20//!
21//! // Create a basic server node
22//! let builder = DefaultNodeBuilder::default()
23//!     .with_node_type(NodeType::Server(SocketAddr::from_str("0.0.0.0:25021").unwrap()))
24//!     .with_backend(BackendType::InMemory);
25//! ```
26//!
27//! # Important Notes
28//! - Server nodes require a valid bind address
29//! - Default backend is filesystem-based when the "filesystem" feature is enabled
30//! - TLS is enabled by default with self-signed certificates
31//! - When using Google services, both services JSON and database config must be set
32//!
33//! # Related Components
34//! - [`NetKernel`]: Core networking kernel that processes node operations
35//! - [`KernelExecutor`]: Executor for running the network kernel
36//! - [`BackendType`]: Storage backend configurations
37
38use citadel_proto::prelude::*;
39
40use citadel_proto::kernel::KernelExecutorArguments;
41use citadel_proto::macros::{ContextRequirements, LocalContextRequirements};
42use citadel_proto::re_imports::RustlsClientConfig;
43use citadel_types::crypto::{HeaderObfuscatorSettings, PreSharedKey};
44use futures::Future;
45use std::fmt::{Debug, Formatter};
46use std::marker::PhantomData;
47use std::path::Path;
48use std::pin::Pin;
49use std::sync::Arc;
50use std::task::{Context, Poll};
51
52/// Used to construct a running client/peer or server instance
53pub struct NodeBuilder<R: Ratchet = StackedRatchet> {
54    hypernode_type: Option<NodeType>,
55    underlying_protocol: Option<ServerUnderlyingProtocol>,
56    backend_type: Option<BackendType>,
57    server_argon_settings: Option<ArgonDefaultServerSettings>,
58    #[cfg(feature = "google-services")]
59    services: Option<ServicesConfig>,
60    server_misc_settings: Option<ServerMiscSettings>,
61    client_tls_config: Option<RustlsClientConfig>,
62    kernel_executor_settings: Option<KernelExecutorSettings>,
63    stun_servers: Option<Vec<String>>,
64    local_only_server_settings: Option<ServerOnlySessionInitSettings>,
65    _ratchet: PhantomData<R>,
66}
67
68/// Default node builder type
69pub type DefaultNodeBuilder = NodeBuilder<StackedRatchet>;
70
71pub type LightweightNodeBuilder = NodeBuilder<MonoRatchet>;
72
73impl<R: Ratchet> Default for NodeBuilder<R> {
74    fn default() -> Self {
75        Self {
76            hypernode_type: None,
77            underlying_protocol: None,
78            backend_type: None,
79            server_argon_settings: None,
80            #[cfg(feature = "google-services")]
81            services: None,
82            server_misc_settings: None,
83            client_tls_config: None,
84            kernel_executor_settings: None,
85            stun_servers: None,
86            local_only_server_settings: None,
87            _ratchet: Default::default(),
88        }
89    }
90}
91
92/// An awaitable future whose return value propagates any internal protocol or kernel-level errors
93pub struct NodeFuture<'a, K> {
94    inner: Pin<Box<dyn FutureContextRequirements<'a, Result<K, NetworkError>>>>,
95    _pd: PhantomData<fn() -> K>,
96}
97
98#[cfg(feature = "multi-threaded")]
99trait FutureContextRequirements<'a, Output>:
100    Future<Output = Output> + Send + LocalContextRequirements<'a>
101{
102}
103#[cfg(feature = "multi-threaded")]
104impl<'a, T: Future<Output = Output> + Send + LocalContextRequirements<'a>, Output>
105    FutureContextRequirements<'a, Output> for T
106{
107}
108
109#[cfg(not(feature = "multi-threaded"))]
110trait FutureContextRequirements<'a, Output>:
111    Future<Output = Output> + LocalContextRequirements<'a>
112{
113}
114#[cfg(not(feature = "multi-threaded"))]
115impl<'a, T: Future<Output = Output> + LocalContextRequirements<'a>, Output>
116    crate::builder::node_builder::FutureContextRequirements<'a, Output> for T
117{
118}
119
120impl<K> Debug for NodeFuture<'_, K> {
121    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
122        write!(f, "NodeFuture")
123    }
124}
125
126impl<K> Future for NodeFuture<'_, K> {
127    type Output = Result<K, NetworkError>;
128
129    fn poll(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
130        self.inner.as_mut().poll(cx)
131    }
132}
133
134impl<R: Ratchet + ContextRequirements> NodeBuilder<R> {
135    /// Returns a future that represents the both the protocol and kernel execution
136    pub fn build<'a, 'b: 'a, K: NetKernel<R> + 'b>(
137        &'a mut self,
138        kernel: K,
139    ) -> anyhow::Result<NodeFuture<'b, K>> {
140        self.check()?;
141        let hypernode_type = self.hypernode_type.take().unwrap_or_default();
142        let backend_type = self.backend_type.take().unwrap_or_else(|| {
143            if cfg!(feature = "filesystem") {
144                // set the home dir for fs type to the home directory
145                let mut home_dir = dirs2::home_dir().unwrap();
146                home_dir.push(format!(".citadel/{}", uuid::Uuid::new_v4().as_u128()));
147                return BackendType::Filesystem(home_dir.to_str().unwrap().to_string());
148            }
149
150            BackendType::InMemory
151        });
152        let server_argon_settings = self.server_argon_settings.take();
153        #[cfg(feature = "google-services")]
154        let server_services_cfg = self.services.take();
155        #[cfg(not(feature = "google-services"))]
156        let server_services_cfg = None;
157        let server_misc_settings = self.server_misc_settings.take();
158        let client_config = self.client_tls_config.take().map(Arc::new);
159        let kernel_executor_settings = self.kernel_executor_settings.take().unwrap_or_default();
160        let stun_servers = self.stun_servers.take();
161
162        let underlying_proto = if let Some(proto) = self.underlying_protocol.take() {
163            proto
164        } else {
165            // default to TLS self-signed to enforce hybrid cryptography
166            ServerUnderlyingProtocol::new_tls_self_signed()
167                .map_err(|err| anyhow::Error::msg(err.into_string()))?
168        };
169
170        if matches!(underlying_proto, ServerUnderlyingProtocol::Tcp(..)) {
171            citadel_logging::warn!(target: "citadel", "⚠️ WARNING ⚠️ TCP is discouraged for production use until The Citadel Protocol has been reviewed. Use TLS automatically by not changing the underlying protocol");
172        }
173
174        let server_only_session_init_settings = self.local_only_server_settings.take();
175
176        Ok(NodeFuture {
177            _pd: Default::default(),
178            inner: Box::pin(async move {
179                log::trace!(target: "citadel", "[NodeBuilder] Checking Tokio runtime ...");
180                let rt = citadel_io::tokio::runtime::Handle::try_current()
181                    .map_err(|err| NetworkError::Generic(err.to_string()))?;
182                log::trace!(target: "citadel", "[NodeBuilder] Creating account manager ...");
183                let account_manager = AccountManager::new(
184                    backend_type,
185                    server_argon_settings,
186                    server_services_cfg,
187                    server_misc_settings,
188                )
189                .await?;
190
191                let args = KernelExecutorArguments {
192                    rt,
193                    hypernode_type,
194                    account_manager,
195                    kernel,
196                    underlying_proto,
197                    client_config,
198                    kernel_executor_settings,
199                    stun_servers,
200                    server_only_session_init_settings,
201                };
202
203                log::trace!(target: "citadel", "[NodeBuilder] Creating KernelExecutor ...");
204                let kernel_executor = KernelExecutor::<_, R>::new(args).await?;
205                log::trace!(target: "citadel", "[NodeBuilder] Executing kernel");
206                kernel_executor.execute().await
207            }),
208        })
209    }
210
211    /// Defines the node type. By default, Peer is used. If a server is desired, a bind address is expected
212    /// ```
213    /// use citadel_sdk::prelude::DefaultNodeBuilder;
214    /// use citadel_proto::prelude::NodeType;
215    ///
216    /// DefaultNodeBuilder::default().with_node_type(NodeType::server("0.0.0.0:25021").unwrap());
217    /// ```
218    pub fn with_node_type(&mut self, node_type: NodeType) -> &mut Self {
219        self.hypernode_type = Some(node_type);
220        self
221    }
222
223    /// Sets the backend used to synchronize client account information. By default, uses the filesystem.
224    /// When the enterprise feature is set, a SQL database (MySQL, PostgreSQL, SQLite) is available. Using a single SQL cluster can be used in combination with
225    /// a cluster of load-balancing running ['NetKernel']'s on different IPs to construct scaled applications
226    pub fn with_backend(&mut self, backend_type: BackendType) -> &mut Self {
227        self.backend_type = Some(backend_type);
228        self
229    }
230
231    /// Sets the desired settings for the [`KernelExecutor`]
232    pub fn with_kernel_executor_settings(
233        &mut self,
234        kernel_executor_settings: KernelExecutorSettings,
235    ) -> &mut Self {
236        self.kernel_executor_settings = Some(kernel_executor_settings);
237        self
238    }
239
240    /// Attaches custom Argon settings for password hashing at the server
241    pub fn with_server_argon_settings(
242        &mut self,
243        settings: ArgonDefaultServerSettings,
244    ) -> &mut Self {
245        self.server_argon_settings = Some(settings);
246        self
247    }
248
249    /// Attaches a google services json path, allowing the use of Google Auth and other dependent services like Realtime Database for android/IOS messaging. Required when using [`Self::with_google_realtime_database_config`]
250    #[cfg(feature = "google-services")]
251    pub fn with_google_services_json_path<T: Into<String>>(&mut self, path: T) -> &mut Self {
252        let cfg = self.get_or_create_services();
253        cfg.google_services_json_path = Some(path.into());
254        self
255    }
256
257    /// Attaches miscellaneous server settings (e.g., transient mode, credential requirements)
258    pub fn with_server_misc_settings(&mut self, misc_settings: ServerMiscSettings) -> &mut Self {
259        self.server_misc_settings = Some(misc_settings);
260        self
261    }
262
263    /// Creates a Google Realtime Database configuration given the project URL and API Key. Requires the use of [`Self::with_google_services_json_path`] to allow minting of JsonWebTokens
264    /// at the central server
265    #[cfg(feature = "google-services")]
266    pub fn with_google_realtime_database_config<T: Into<String>, R: Into<String>>(
267        &mut self,
268        url: T,
269        api_key: R,
270    ) -> &mut Self {
271        let cfg = self.get_or_create_services();
272        cfg.google_rtdb = Some(RtdbConfig {
273            url: url.into(),
274            api_key: api_key.into(),
275        });
276        self
277    }
278
279    /// Sets the underlying protocol for the server
280    /// Default: TLS transport w/ self-signed cert
281    pub fn with_underlying_protocol(&mut self, proto: ServerUnderlyingProtocol) -> &mut Self {
282        self.underlying_protocol = Some(proto);
283        self
284    }
285
286    #[cfg(feature = "google-services")]
287    fn get_or_create_services(&mut self) -> &mut ServicesConfig {
288        if self.services.is_some() {
289            self.services.as_mut().unwrap()
290        } else {
291            let cfg = ServicesConfig::default();
292            self.services = Some(cfg);
293            self.services.as_mut().unwrap()
294        }
295    }
296
297    /// Loads the accepted cert chain stored by the local operating system
298    /// If a custom set of certs is required, run [`Self::with_custom_certs`]
299    /// This is the default if no [`RustlsClientConfig`] is specified
300    pub async fn with_native_certs(&mut self) -> anyhow::Result<&mut Self> {
301        let certs = citadel_proto::re_imports::load_native_certs_async().await?;
302        self.client_tls_config = Some(citadel_proto::re_imports::cert_vec_to_secure_client_config(
303            &certs,
304        )?);
305        Ok(self)
306    }
307
308    /// The client will skip unconditionally server certificate verification
309    /// This is not recommended
310    pub fn with_insecure_skip_cert_verification(&mut self) -> &mut Self {
311        self.client_tls_config = Some(citadel_proto::re_imports::insecure::rustls_client_config());
312        self
313    }
314
315    /// Loads a custom list of certs into the acceptable certificate list. Connections that present server certificates
316    /// that are outside of this list during the handshake process are refused
317    pub fn with_custom_certs<T: AsRef<[u8]>>(
318        &mut self,
319        custom_certs: &[T],
320    ) -> anyhow::Result<&mut Self> {
321        let cfg = citadel_proto::re_imports::create_rustls_client_config(custom_certs)?;
322        self.client_tls_config = Some(cfg);
323        Ok(self)
324    }
325
326    /// The file should be a DER formatted certificate
327    #[cfg(feature = "std")]
328    pub async fn with_pem_file<P: AsRef<Path>>(&mut self, path: P) -> anyhow::Result<&mut Self> {
329        let mut der = std::io::Cursor::new(citadel_io::tokio::fs::read(path).await?);
330        let certs = citadel_proto::re_imports::rustls_pemfile::certs(&mut der).collect::<Vec<_>>();
331        // iter certs and try collecting on the results
332        let mut filtered_certs = Vec::new();
333        for cert in certs {
334            filtered_certs.push(cert?);
335        }
336        self.client_tls_config = Some(citadel_proto::re_imports::create_rustls_client_config(
337            &filtered_certs,
338        )?);
339        Ok(self)
340    }
341
342    /// Specifies custom STUN servers. If left unspecified, will use the defaults (twilio and Google STUN servers)
343    pub fn with_stun_servers<T: Into<String>, S: Into<Vec<T>>>(&mut self, servers: S) -> &mut Self {
344        self.stun_servers = Some(servers.into().into_iter().map(|t| t.into()).collect());
345        self
346    }
347
348    /// Sets the pre-shared key for the server. Only a server should set this value
349    /// If no value is set, any client can connect to the server. If a pre-shared key
350    /// is specified, the client must have the matching pre-shared key in order to
351    /// register and connect with the server.
352    pub fn with_server_password<T: Into<PreSharedKey>>(&mut self, password: T) -> &mut Self {
353        let mut server_only_settings = self.local_only_server_settings.clone().unwrap_or_default();
354        server_only_settings.declared_pre_shared_key = Some(password.into());
355        self.local_only_server_settings = Some(server_only_settings);
356        self
357    }
358
359    /// Sets the header obfuscator settings for the server
360    pub fn with_server_declared_header_obfuscation<T: Into<HeaderObfuscatorSettings>>(
361        &mut self,
362        header_obfuscator_settings: T,
363    ) -> &mut Self {
364        let mut server_only_settings = self.local_only_server_settings.clone().unwrap_or_default();
365        server_only_settings.declared_header_obfuscation_setting =
366            header_obfuscator_settings.into();
367        self.local_only_server_settings = Some(server_only_settings);
368        self
369    }
370
371    fn check(&self) -> anyhow::Result<()> {
372        #[cfg(feature = "google-services")]
373        if let Some(svc) = self.services.as_ref() {
374            if svc.google_rtdb.is_some() && svc.google_services_json_path.is_none() {
375                return Err(anyhow::Error::msg(
376                    "Google realtime database is enabled, yet, a services path is not provided",
377                ));
378            }
379        }
380
381        if let Some(stun_servers) = self.stun_servers.as_ref() {
382            if stun_servers.len() != 3 {
383                return Err(anyhow::Error::msg(
384                    "There must be exactly 3 specified STUN servers",
385                ));
386            }
387        }
388
389        Ok(())
390    }
391}
392
393#[cfg(test)]
394mod tests {
395    use crate::builder::node_builder::DefaultNodeBuilder;
396    use crate::prefabs::server::empty::EmptyKernel;
397    use crate::prelude::{BackendType, NodeType};
398    use citadel_io::tokio;
399    use citadel_proto::prelude::{KernelExecutorSettings, ServerUnderlyingProtocol};
400    use rstest::rstest;
401    use std::str::FromStr;
402
403    #[test]
404    #[cfg(feature = "google-services")]
405    fn okay_config() {
406        let _ = DefaultNodeBuilder::default()
407            .with_google_realtime_database_config("123", "456")
408            .with_google_services_json_path("abc")
409            .build(EmptyKernel::default())
410            .unwrap();
411    }
412
413    #[test]
414    #[cfg(feature = "google-services")]
415    fn bad_config() {
416        assert!(DefaultNodeBuilder::default()
417            .with_google_realtime_database_config("123", "456")
418            .build(EmptyKernel::default())
419            .is_err());
420    }
421
422    #[test]
423    fn bad_config2() {
424        assert!(DefaultNodeBuilder::default()
425            .with_stun_servers(["dummy1", "dummy2"])
426            .build(EmptyKernel::default())
427            .is_err());
428    }
429
430    #[rstest]
431    #[tokio::test]
432    #[timeout(std::time::Duration::from_secs(60))]
433    #[allow(clippy::let_underscore_must_use)]
434    async fn test_options(
435        #[values(ServerUnderlyingProtocol::new_quic_self_signed(), ServerUnderlyingProtocol::new_tls_self_signed().unwrap()
436        )]
437        underlying_protocol: ServerUnderlyingProtocol,
438        #[values(NodeType::Peer, NodeType::Server(std::net::SocketAddr::from_str("127.0.0.1:9999").unwrap()
439        ))]
440        node_type: NodeType,
441        #[values(KernelExecutorSettings::default(), KernelExecutorSettings::default().with_max_concurrency(2)
442        )]
443        kernel_settings: KernelExecutorSettings,
444        #[values(BackendType::InMemory, BackendType::new("file:/hello_world/path/").unwrap())]
445        backend_type: BackendType,
446    ) {
447        let mut builder = DefaultNodeBuilder::default();
448        let _ = builder
449            .with_underlying_protocol(underlying_protocol.clone())
450            .with_backend(backend_type.clone())
451            .with_node_type(node_type)
452            .with_kernel_executor_settings(kernel_settings.clone())
453            .with_insecure_skip_cert_verification()
454            .with_stun_servers(["dummy1", "dummy1", "dummy3"])
455            .with_native_certs()
456            .await
457            .unwrap();
458
459        assert!(builder.underlying_protocol.is_some());
460        assert_eq!(backend_type, builder.backend_type.clone().unwrap());
461        assert_eq!(node_type, builder.hypernode_type.unwrap());
462        assert_eq!(
463            kernel_settings,
464            builder.kernel_executor_settings.clone().unwrap()
465        );
466
467        drop(builder.build(EmptyKernel::default()).unwrap());
468    }
469}
citadel_sdk/builder/node_builder.rs

citadel_sdk/builder/
node_builder.rs
