Initial commit: NetworkCity — network traffic as a neon city

A native macOS network monitor that renders live traffic as a top-down neon city: your Mac is downtown, remote orgs are glowing districts, and traffic is cars of light driving the roads. Architecture: - NetworkCityCore: swappable data layer behind a ConnectionSource protocol (nettop-backed today), plus pure/tested logic — traffic diffing, org classification (reverse-DNS + CIDR), traffic classes, hub-and-spoke expansion policy, label anti-overlap, and latency→distance layout. - NetworkCityApp: SwiftUI + SpriteKit city — auto-expanding districts, protocol-coloured cars, click-to-inspect panel, and latency-as-distance (districts glide to their measured RTT). - nettop-probe: CLI proof of the data layer. 44 tests passing. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
2026-06-13 08:43:32 -07:00
commit c08fc277a9
33 changed files with 2499 additions and 0 deletions
@@ -0,0 +1,46 @@
+import Foundation
+import Darwin
+
+/// Best-effort reverse DNS (IP -> PTR hostname). Blocking — call it off the main
+/// thread. Returns nil when there's no PTR record (we don't want a numeric echo).
+public enum ReverseDNS {
+
+    public static func resolve(_ ip: String) -> String? {
+        var storage = sockaddr_storage()
+        var length: socklen_t = 0
+
+        if ip.contains(":") {
+            var sa = sockaddr_in6()
+            sa.sin6_family = sa_family_t(AF_INET6)
+            sa.sin6_len = UInt8(MemoryLayout<sockaddr_in6>.size)
+            guard inet_pton(AF_INET6, ip, &sa.sin6_addr) == 1 else { return nil }
+            withUnsafeBytes(of: &sa) { src in
+                withUnsafeMutableBytes(of: &storage) { dst in
+                    dst.copyMemory(from: UnsafeRawBufferPointer(rebasing: src[0..<MemoryLayout<sockaddr_in6>.size]))
+                }
+            }
+            length = socklen_t(MemoryLayout<sockaddr_in6>.size)
+        } else {
+            var sa = sockaddr_in()
+            sa.sin_family = sa_family_t(AF_INET)
+            sa.sin_len = UInt8(MemoryLayout<sockaddr_in>.size)
+            guard inet_pton(AF_INET, ip, &sa.sin_addr) == 1 else { return nil }
+            withUnsafeBytes(of: &sa) { src in
+                withUnsafeMutableBytes(of: &storage) { dst in
+                    dst.copyMemory(from: UnsafeRawBufferPointer(rebasing: src[0..<MemoryLayout<sockaddr_in>.size]))
+                }
+            }
+            length = socklen_t(MemoryLayout<sockaddr_in>.size)
+        }
+
+        var host = [CChar](repeating: 0, count: Int(NI_MAXHOST))
+        let result = withUnsafePointer(to: &storage) { ptr in
+            ptr.withMemoryRebound(to: sockaddr.self, capacity: 1) { sa in
+                getnameinfo(sa, length, &host, socklen_t(host.count), nil, 0, NI_NAMEREQD)
+            }
+        }
+        guard result == 0 else { return nil }
+        let name = String(cString: host)
+        return name.isEmpty ? nil : name
+    }
+}