setup api bindings for reaching out to light servers

.gitignore

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+/target

Cargo.toml

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+[package]
+name = "lightclient"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+reqwest = { version = "0.11", features = ["json"] }
+tokio = { version = "1", features = ["full"] }
+eyre = "0.6.8"
+serde = { version = "1.0.143", features = ["derive"] }

src/main.rs

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+use eyre::Result;
+use serde::Deserialize;
+
+#[tokio::main]
+async fn main() -> Result<()> {
+
+    let client = LightClient::new("http://testing.prater.beacon-api.nimbus.team");
+    let bootstrap = client.get_bootstrap("0x29d7ba1ef23b01a8b9024ee0cd73d0b7181edc0eb16e4645300092838c07783f").await?;
+    
+    let current_slot = bootstrap.header.slot;
+    let current_sync_period = LightClient::calc_sync_period(current_slot.parse()?);
+    let next_sync_period = current_sync_period + 1;
+
+    println!("{}", next_sync_period);
+
+    let updates = client.get_updates(next_sync_period).await?;
+    let attested_headers = updates.iter().map(|update| &update.attested_header).collect::<Vec<&Header>>();
+    let finalized_headers = updates.iter().map(|update| &update.finalized_header).collect::<Vec<&Header>>();
+
+    println!("{:?}", attested_headers);
+    println!("{:?}", finalized_headers);
+
+    let finality_update = client.get_finality_update().await?;
+
+    println!("{:?}", finality_update.attested_header);
+    println!("{:?}", finality_update.finalized_header);
+
+    Ok(())
+}
+
+struct LightClient {
+    nimbus_rpc: String,
+}
+
+impl LightClient {
+    fn new(nimbus_rpc: &str) -> LightClient {
+        LightClient { nimbus_rpc: nimbus_rpc.to_string() }
+    }
+
+    async fn get_bootstrap(&self, block_root: &str) -> Result<Bootstrap> {
+        let req = format!("{}/eth/v0/beacon/light_client/bootstrap/{}", self.nimbus_rpc, block_root);
+        let res = reqwest::get(req).await?.json::<BootstrapResponse>().await?;
+        Ok(res.data.v)
+    }
+
+    async fn get_updates(&self, period: u64) -> Result<Vec<Update>> {
+        let req = format!("{}/eth/v0/beacon/light_client/updates?start_period={}&count=1000", self.nimbus_rpc, period);
+        let res = reqwest::get(req).await?.json::<UpdateResponse>().await?;
+        Ok(res.data)
+    }
+
+    async fn get_finality_update(&self) -> Result<FinalityUpdate> {
+        let req = format!("{}/eth/v0/beacon/light_client/finality_update", self.nimbus_rpc);
+        let res = reqwest::get(req).await?.json::<FinalityUpdateResponse>().await?;
+        Ok(res.data)
+    }
+
+    fn calc_sync_period(slot: u64) -> u64 {
+        let epoch = slot / 32;
+        epoch / 256
+    }
+}
+
+#[derive(Deserialize, Debug)]
+struct BootstrapResponse {
+    data: BootstrapData,
+}
+
+#[derive(Deserialize, Debug)]
+struct BootstrapData {
+    v: Bootstrap,
+}
+
+#[derive(Deserialize, Debug)]
+struct Bootstrap {
+    header: Header,
+    current_sync_committee: SyncCommittee,
+    current_sync_committee_branch: Vec<String>,
+}
+
+#[derive(Deserialize, Debug, Clone)]
+struct SyncCommittee {
+    pubkeys: Vec<String>,
+    aggregate_pubkey: String,
+}
+
+#[derive(Deserialize, Debug, Clone)]
+struct Header {
+    slot: String,
+}
+
+#[derive(Deserialize, Debug)]
+struct UpdateResponse {
+    data: Vec<Update>,
+}
+
+#[derive(Deserialize, Debug, Clone)]
+struct Update {
+    attested_header: Header,
+    next_sync_committee: SyncCommittee,
+    next_sync_committee_branch: Vec<String>,
+    finalized_header: Header,
+    finality_branch: Vec<String>,
+    sync_aggregate: SyncAggregate,
+}
+
+#[derive(Deserialize, Debug, Clone)]
+struct SyncAggregate {
+    sync_committee_bits: String,
+    sync_committee_signature: String,
+}
+
+#[derive(Deserialize, Debug)]
+struct FinalityUpdateResponse {
+    data: FinalityUpdate,
+}
+
+#[derive(Deserialize, Debug)]
+struct FinalityUpdate {
+    attested_header: Header,
+    finalized_header: Header,
+    finality_branch: Vec<String>,
+    sync_aggregate: SyncAggregate,
+    signature_slot: String,
+}