realigning commits

1 files changed, 82 insertions, 0 deletions

diff --git a/DomainDig/RedirectChainService.swift b/DomainDig/RedirectChainService.swift
new file mode 100644
index 0000000..7a23a5e
--- /dev/null
+++ b/DomainDig/RedirectChainService.swift
@@ -0,0 +1,82 @@
+import Foundation
+
+struct RedirectChainService {
+    static func trace(domain: String) async throws -> [RedirectHop] {
+        // Try HTTPS first (avoids ATS issues), fall back to HTTP if it fails entirely
+        do {
+            return try await followChain(startingURL: URL(string: "https://\(domain)")!)
+        } catch {
+            return try await followChain(startingURL: URL(string: "http://\(domain)")!)
+        }
+    }
+
+    private static func followChain(startingURL: URL) async throws -> [RedirectHop] {
+        let delegate = NoRedirectDelegate()
+        let session = URLSession(
+            configuration: .ephemeral,
+            delegate: delegate,
+            delegateQueue: nil
+        )
+        defer { session.invalidateAndCancel() }
+
+        var hops: [RedirectHop] = []
+        var currentURL = startingURL
+        let maxRedirects = 10
+
+        for step in 1...maxRedirects + 1 {
+            var request = URLRequest(url: currentURL, timeoutInterval: 10)
+            request.httpMethod = "GET"
+
+            let (_, response) = try await session.data(for: request)
+
+            guard let httpResponse = response as? HTTPURLResponse else {
+                throw URLError(.badServerResponse)
+            }
+
+            let statusCode = httpResponse.statusCode
+            let isRedirect = (300...399).contains(statusCode)
+
+            if isRedirect, let location = httpResponse.value(forHTTPHeaderField: "Location") {
+                hops.append(RedirectHop(
+                    stepNumber: step,
+                    statusCode: statusCode,
+                    url: currentURL.absoluteString,
+                    isFinal: false
+                ))
+
+                // Resolve relative redirects
+                if let nextURL = URL(string: location, relativeTo: currentURL)?.absoluteURL {
+                    currentURL = nextURL
+                } else {
+                    break
+                }
+
+                if step > maxRedirects { break }
+            } else {
+                // Non-redirect — this is the final destination
+                hops.append(RedirectHop(
+                    stepNumber: step,
+                    statusCode: statusCode,
+                    url: currentURL.absoluteString,
+                    isFinal: true
+                ))
+                break
+            }
+        }
+
+        return hops
+    }
+}
+
+private final class NoRedirectDelegate: NSObject, URLSessionTaskDelegate, @unchecked Sendable {
+    func urlSession(
+        _ session: URLSession,
+        task: URLSessionTask,
+        willPerformHTTPRedirection response: HTTPURLResponse,
+        newRequest request: URLRequest,
+        completionHandler: @escaping (URLRequest?) -> Void
+    ) {
+        // Don't follow redirects automatically — return nil to stop
+        completionHandler(nil)
+    }
+}