Get around CCP bootstrap relay banning by caching user's relays as their bootstrap relays

Changelog-Fixed: Get around CCP bootstrap relay banning by caching user's relays as their bootstrap relays

damus/Util/Relays/RelayBootstrap.swift

@@ -0,0 +1,44 @@
+//
+//  RelayBootstrap.swift
+//  damus
+//
+//  Created by William Casarin on 2023-04-04.
+//
+
+import Foundation
+
+fileprivate let BOOTSTRAP_RELAYS = [
+    "wss://relay.damus.io",
+    "wss://eden.nostr.land",
+    "wss://nostr.wine",
+    "wss://nos.lol",
+]
+
+func bootstrap_relays_setting_key(pubkey: String) -> String {
+    return pk_setting_key(pubkey, key: "bootstrap_relays")
+}
+
+func save_bootstrap_relays(pubkey: String, relays: [String])  {
+    let key = bootstrap_relays_setting_key(pubkey: pubkey)
+    
+    UserDefaults.standard.set(relays, forKey: key)
+}
+
+func load_bootstrap_relays(pubkey: String) -> [String] {
+    let key = bootstrap_relays_setting_key(pubkey: pubkey)
+    
+    guard let relays = UserDefaults.standard.stringArray(forKey: key) else {
+        print("loading default bootstrap relays")
+        return BOOTSTRAP_RELAYS.map { $0 }
+    }
+    
+    if relays.count == 0 {
+        print("loading default bootstrap relays")
+        return BOOTSTRAP_RELAYS.map { $0 }
+    }
+    
+    let loaded_relays = Array(Set(relays + BOOTSTRAP_RELAYS))
+    print("Loading custom bootstrap relays: \(loaded_relays)")
+    return loaded_relays
+}
+