Subscan Module

SubscanModule components are the core components that can be executed by Subscan. Each module capable of performing subdomain discovery is named a SubscanModule, and when the subscan scan command is run, these modules are read from an in-memory cache and executed asynchronously. This architecture makes Subscan extensible and modular

A SubscanModule may contain various components such as Requester and Extractor. Most modules implemented in Subscan use these components. You can list the implemented modules with their details using the subscan module list command. If you'd like to view the in-memory cache, you can check the CacheManager struct, which is another component designed for operations like filtering the cache or accessing a specific module

Create Your Own Module

Each SubscanModule component should be implemented following the interface below. For a better understanding, you can explore the docs.rs page and review the crates listed below

• async_trait
• enum_dispatch

#[async_trait]
#[enum_dispatch]
pub trait SubscanModuleInterface: Sync + Send {
    // Returns module name, name should clarify what does module
    async fn name(&self) -> &str;
    // Loads `.env` file and fetches module environment variables with variable name.
    // If system environment variable set with same name, `.env` file will be overrode
    async fn envs(&self) -> SubscanModuleEnvs {
        self.name().await.into()
    }
    // Returns module requester address as a mutable reference if available
    async fn requester(&self) -> Option<&Mutex<RequesterDispatcher>>;
    // Returns module extractor reference if available
    async fn extractor(&self) -> Option<&SubdomainExtractorDispatcher>;
    // Just like a `main` method, when the module run this `run` method will be called.
    // So this method should do everything
    async fn run(&mut self, domain: &str) -> Result<SubscanModuleResult>;
}

Below is a simple example of a custom module. For more examples, you can check the examples/ folder on the project's GitHub page. You can also refer to the source code of predefined requester implementations for a better understanding

pub struct CustomModule {
    pub requester: Mutex<RequesterDispatcher>,
    pub extractor: SubdomainExtractorDispatcher,
}

#[async_trait]
impl SubscanModuleInterface for CustomModule {
    async fn name(&self) -> &str {
        &"name"
    }

    async fn requester(&self) -> Option<&Mutex<RequesterDispatcher>> {
        Some(&self.requester)
    }

    async fn extractor(&self) -> Option<&SubdomainExtractorDispatcher> {
        Some(&self.extractor)
    }

    async fn run(&mut self, _domain: &str) -> Result<SubscanModuleResult> {
        let mut result: SubscanModuleResult = self.name().await.into();

        let subdomains = BTreeSet::from_iter([
            Subdomain::from("bar.foo.com"),
            Subdomain::from("baz.foo.com"),
        ]);

        result.extend(subdomains);

        Ok(result.with_finished().await)
    }
}