sn-fetch PoC: range probe, weighted planner, parallel segments, reassembly + sha256

server/crates/sn-fetch/src/exit.rs

@@ -0,0 +1,73 @@
+//! Exit abstraction: an "exit" is one internet uplink through which
+//! segment requests can be sent.
+//!
+//! PoC v0 ships only [`LocalExit`] (the household's own connection, no
+//! detour). The registry/trait structure is deliberately ready so a
+//! future exit implementation can route HTTP through a neighbour over
+//! the mesh (e.g. via a per-exit proxy or tunnel) without changing the
+//! planner or executor.
+
+use std::collections::BTreeMap;
+use std::sync::Arc;
+use std::time::Duration;
+
+use crate::error::FetchError;
+use crate::types::ExitId;
+
+/// An internet uplink able to issue HTTP requests.
+pub trait HttpExit: Send + Sync {
+    fn id(&self) -> ExitId;
+
+    /// Client whose connections go out through this exit.
+    fn client(&self) -> &reqwest::Client;
+}
+
+/// The household's own uplink: plain outgoing HTTP, no detour.
+#[derive(Debug)]
+pub struct LocalExit {
+    id: ExitId,
+    client: reqwest::Client,
+}
+
+impl LocalExit {
+    pub fn new(id: ExitId) -> Result<Self, FetchError> {
+        let client = reqwest::Client::builder()
+            .connect_timeout(Duration::from_secs(30))
+            .build()?;
+        Ok(Self { id, client })
+    }
+}
+
+impl HttpExit for LocalExit {
+    fn id(&self) -> ExitId {
+        self.id
+    }
+
+    fn client(&self) -> &reqwest::Client {
+        &self.client
+    }
+}
+
+/// All exits available for a fetch, keyed by id.
+#[derive(Default, Clone)]
+pub struct ExitRegistry {
+    exits: BTreeMap<ExitId, Arc<dyn HttpExit>>,
+}
+
+impl ExitRegistry {
+    pub fn empty() -> Self {
+        Self::default()
+    }
+
+    pub fn register(&mut self, exit: Arc<dyn HttpExit>) {
+        self.exits.insert(exit.id(), exit);
+    }
+
+    pub fn get(&self, id: ExitId) -> Result<&Arc<dyn HttpExit>, FetchError> {
+        self.exits.get(&id).ok_or(FetchError::UnknownExit(id))
+    }
+
+    pub fn ids(&self) -> Vec<ExitId> {
+        self.exits.keys().copied().collect()
+    }
+}