NIP05 Verification

Changelog-Added: Added NIP05 Verification

damus/Util/NIP05.swift

@@ -0,0 +1,65 @@
+//
+//  NIP05.swift
+//  damus
+//
+//  Created by William Casarin on 2023-01-04.
+//
+
+import Foundation
+
+struct NIP05 {
+    let username: String
+    let host: String
+    
+    var url: URL? {
+        URL(string: "https://\(host)/.well-known/nostr.json?name=\(username)")
+    }
+    
+    static func parse(_ nip05: String) -> NIP05? {
+        let parts = nip05.split(separator: "@")
+        guard parts.count == 2 else {
+            return nil
+        }
+        return NIP05(username: String(parts[0]), host: String(parts[1]))
+    }
+}
+
+
+struct NIP05Response: Decodable {
+    let names: [String: String]
+    let relays: [String: [String]]?
+}
+
+enum NIP05Validation {
+    case invalid
+    case valid
+}
+
+func validate_nip05(pubkey: String, nip05_str: String) async -> NIP05? {
+    guard let nip05 = NIP05.parse(nip05_str) else {
+        return nil
+    }
+    
+    guard let url = nip05.url else {
+        return nil
+    }
+    
+    guard let ret = try? await URLSession.shared.data(from: url) else {
+        return nil
+    }
+    let dat = ret.0
+    
+    guard let decoded = try? JSONDecoder().decode(NIP05Response.self, from: dat) else {
+        return nil
+    }
+    
+    guard let stored_pk = decoded.names[nip05.username] else {
+        return nil
+    }
+    
+    guard stored_pk == pubkey else {
+        return nil
+    }
+    
+    return nip05
+}