fix: relogin when webvpn mistakenly returns html rather than payload

DanXi Kit/Utils/Proxy.swift

@@ -12,6 +12,24 @@ public class Proxy {
         ProxySettings.shared.enableProxy && FudanKit.CredentialStore.shared.credentialPresent
     }
 
+    private func validateResponse(_ response: URLResponse) -> Bool {
+        /**
+         WebVPN may occasionally return HTML instead of the expected payload; when this occurs, re-authenticate.
+         This method can be modified to handle other cases where WebVPN returns unexpected responses.
+         */
+
+        if let mimeType = response.mimeType, mimeType.contains("text/html") {
+            return false
+        }
+        if let httpResponse = response as? HTTPURLResponse,
+           let contentType = httpResponse.value(forHTTPHeaderField: "Content-Type"),
+           contentType.contains("text/html") {
+           return false
+        }
+
+        return true
+    }
+
     func upload(for request: URLRequest, from bodyData: Data) async throws -> (Data, URLResponse) {
         guard shouldTryProxy, outsideCampus else {
             return try await URLSession.shared.upload(for: request, from: bodyData)
@@ -20,6 +38,9 @@ public class Proxy {
         let proxiedRequest = createProxiedRequest(request: request)
         // we do not try to relogin here, because it's highly unlikely to fail
         return try await URLSession.shared.upload(for: proxiedRequest, from: bodyData)
+
+        // this method is not used yet so no validateResponse check for now
+        // todo: add validateResponse to this method when being used
     }
 
     func data(for request: URLRequest) async throws -> (Data, URLResponse) {
@@ -59,7 +80,14 @@ public class Proxy {
         // use proxy
 
         let proxiedRequest = createProxiedRequest(request: request)
-        return try await FudanKit.Authenticator.neo.authenticateRequest(request: proxiedRequest, loginURL: URL(string: "https://webvpn.fudan.edu.cn/login?cas_login=true")!)
+        let (data, response) = try await FudanKit.Authenticator.neo.authenticateRequest(request: proxiedRequest, loginURL: URL(string: "https://webvpn.fudan.edu.cn/login?cas_login=true")!)
+
+        // check if webvpn returns the correct data format
+        if validateResponse(response) {
+            return (data, response)
+        } else {
+            return try await FudanKit.Authenticator.neo.authenticateRequest(request: proxiedRequest, loginURL: URL(string: "https://webvpn.fudan.edu.cn/login?cas_login=true")!, forceRelogin: true)
+        }
     }
 
     public func createProxiedURL(url: URL) -> URL {

Fudan Kit/Authentication/Authenticator.swift

@@ -51,10 +51,10 @@ public actor Authenticator {
         throw CampusError.loginFailed
     }
 
-    public func authenticateRequest(request: URLRequest, loginURL: URL) async throws -> (Data, URLResponse) {
+    public func authenticateRequest(request: URLRequest, loginURL: URL, forceRelogin: Bool = false) async throws -> (Data, URLResponse) {
         guard let host = request.url?.host else { throw LocatableError() }
 
-        if !isLogged(host: host) {
+        if (!isLogged(host: host) || forceRelogin)  {
             _ = try await performAuthenticate(url: loginURL)
         }