feat(l1): add mainnet as preset network (#2459)

**Motivation**
Adds mainnet bootnodes & genesis file so we can connect to mainnet by
passing `--network mainnet`
<!-- Why does this pull request exist? What are its goals? -->

**Description**
* add mainnet bootnodes & genesis file
* recognize mainnet as preset network
* update docs
<!-- A clear and concise general description of the changes this PR
introduces -->

<!-- Link to issues: Resolves #111, Resolves #222 -->

Contributes to #72 

**Notes**
Mainnet genesis file is quite large, it is copied from
[here](https://github.com/eth-clients/mainnet/blob/main/metadata/genesis.json)

Author: fmoletta

README.md

@@ -205,7 +205,7 @@ Options:
 
 Node options:
       --network <GENESIS_FILE_PATH>
-          Alternatively, the name of a known network can be provided instead to use its preset genesis file and include its preset bootnodes. The networks currently supported include holesky, sepolia and hoodi.
+          Alternatively, the name of a known network can be provided instead to use its preset genesis file and include its preset bootnodes. The networks currently supported include holesky, sepolia, hoodi and mainnet.
 
       --datadir <DATABASE_DIRECTORY>
           If the datadir is the word `memory`, ethrex will use the `InMemory Engine`.

cmd/ethrex/cli.rs

@@ -36,7 +36,7 @@ pub struct Options {
         long = "network",
         value_name = "GENESIS_FILE_PATH",
         help = "Receives a `Genesis` struct in json format. This is the only argument which is required. You can look at some example genesis files at `test_data/genesis*`.",
-        long_help = "Alternatively, the name of a known network can be provided instead to use its preset genesis file and include its preset bootnodes. The networks currently supported include holesky, sepolia and hoodi.",
+        long_help = "Alternatively, the name of a known network can be provided instead to use its preset genesis file and include its preset bootnodes. The networks currently supported include holesky, sepolia, hoodi and mainnet.",
         help_heading = "Node options"
     )]
     pub network: Option<String>,

cmd/ethrex/initializers.rs

@@ -257,6 +257,9 @@ pub fn get_network(opts: &Options) -> String {
     if network == "hoodi" {
         network = String::from(networks::HOODI_GENESIS_PATH);
     }
+    if network == "mainnet" {
+        network = String::from(networks::MAINNET_GENESIS_PATH);
+    }
 
     network
 }
@@ -280,6 +283,11 @@ pub fn get_bootnodes(opts: &Options, network: &str, data_dir: &str) -> Vec<Node>
         bootnodes.extend(networks::HOODI_BOOTNODES.iter());
     }
 
+    if network == networks::MAINNET_GENESIS_PATH {
+        info!("Adding mainnet preset bootnodes");
+        bootnodes.extend(networks::MAINNET_BOOTNODES.iter());
+    }
+
     if bootnodes.is_empty() {
         warn!("No bootnodes specified. This node will not be able to connect to the network.");
     }

cmd/ethrex/networks.rs

@@ -10,6 +10,9 @@ const SEPOLIA_BOOTNODES_PATH: &str = "cmd/ethrex/networks/sepolia/bootnodes.json
 pub const HOODI_GENESIS_PATH: &str = "cmd/ethrex/networks/hoodi/genesis.json";
 const HOODI_BOOTNODES_PATH: &str = "cmd/ethrex/networks/hoodi/bootnodes.json";
 
+pub const MAINNET_GENESIS_PATH: &str = "cmd/ethrex/networks/mainnet/genesis.json";
+const MAINNET_BOOTNODES_PATH: &str = "cmd/ethrex/networks/mainnet/bootnodes.json";
+
 lazy_static! {
     pub static ref HOLESKY_BOOTNODES: Vec<Node> = serde_json::from_reader(
         std::fs::File::open(HOLESKY_BOOTNODES_PATH).expect("Failed to open holesky bootnodes file")
@@ -23,4 +26,8 @@ lazy_static! {
         std::fs::File::open(HOODI_BOOTNODES_PATH).expect("Failed to open hoodi bootnodes file")
     )
     .expect("Failed to parse hoodi bootnodes file");
+    pub static ref MAINNET_BOOTNODES: Vec<Node> = serde_json::from_reader(
+        std::fs::File::open(MAINNET_BOOTNODES_PATH).expect("Failed to open mainnet bootnodes file")
+    )
+    .expect("Failed to parse mainnet bootnodes file");
 }

cmd/ethrex/networks/mainnet/bootnodes.json

@@ -0,0 +1,6 @@
+[
+    "enode://d860a01f9722d78051619d1e2351aba3f43f943f6f00718d1b9baa4101932a1f5011f16bb2b1bb35db20d6fe28fa0bf09636d26a87d31de9ec6203eeedb1f666@18.138.108.67:30303",
+    "enode://22a8232c3abc76a16ae9d6c3b164f98775fe226f0917b0ca871128a74a8e9630b458460865bab457221f1d448dd9791d24c4e5d88786180ac185df813a68d4de@3.209.45.79:30303",
+    "enode://2b252ab6a1d0f971d9722cb839a42cb81db019ba44c08754628ab4a823487071b5695317c8ccd085219c3a03af063495b2f1da8d18218da2d6a82981b45e6ffc@65.108.70.101:30303",
+    "enode://4aeb4ab6c14b23e2c4cfdce879c04b0748a20d8e9b59e25ded2a08143e265c6c25936e74cbc8e641e3312ca288673d91f2f93f8e277de3cfa444ecdaaf982052@157.90.35.166:30303"
+]