Tweak AndroidMessageHandler behavior for WCF support

src/Mono.Android/Xamarin.Android.Net/AndroidMessageHandler.cs

@@ -69,11 +69,46 @@ sealed class RequestRedirectionState
  public bool MethodChanged;
  }
 
+ /// <summary>
+ /// Some requests require modification to the set of headers returned from the native client.
+ /// However, the headers collection in it is immutable, so we need to perform the adjustments
+ /// in CopyHeaders. This class describes the necessary operations.
+ /// </summary>
+ sealed class ContentState
+ {
+ public bool? RemoveContentLengthHeader;
+
+ /// <summary>
+ /// If this is `true`, then `NewContentEncodingHeaderValue` is entirely ignored
+ /// </summary>
+ public bool? RemoveContentEncodingHeader;
+
+ /// <summary>
+ /// New 'Content-Encoding' header value. Ignored if not null and empty.
+ /// </summary>
+ public List<string>? NewContentEncodingHeaderValue;
+
+ /// <summary>
+ /// Reset the class to values that indicate there's no action to take. MUST be
+ /// called BEFORE any of the class members are assigned values and AFTER the state
+ /// modification is applied
+ /// </summary>
+ public void Reset ()
+ {
+ RemoveContentEncodingHeader = null;
+ RemoveContentLengthHeader = null;
+ NewContentEncodingHeaderValue = null;
+ }
+ }
+
  internal const string LOG_APP = "monodroid-net";
 
  const string GZIP_ENCODING = "gzip";
  const string DEFLATE_ENCODING = "deflate";
+ const string BROTLI_ENCODING = "br";
  const string IDENTITY_ENCODING = "identity";
+ const string ContentEncodingHeaderName = "Content-Encoding";
+ const string ContentLengthHeaderName = "Content-Length";
 
  static readonly IDictionary<string, string> headerSeparators = new Dictionary<string, string> {
  ["User-Agent"] = " ",
@@ -82,9 +117,9 @@ sealed class RequestRedirectionState
  static readonly HashSet <string> known_content_headers = new HashSet <string> (StringComparer.OrdinalIgnoreCase) {
  "Allow",
  "Content-Disposition",
- "Content-Encoding",
+ ContentEncodingHeaderName,
  "Content-Language",
- "Content-Length",
+ ContentLengthHeaderName,
  "Content-Location",
  "Content-MD5",
  "Content-Range",
@@ -571,6 +606,7 @@ internal Task WriteRequestContentToOutputInternal (HttpRequestMessage request, H
  CancellationTokenRegistration cancelRegistration = default (CancellationTokenRegistration);
  HttpStatusCode statusCode = HttpStatusCode.OK;
  Uri? connectionUri = null;
+ var contentState = new ContentState ();
 
  try {
  cancelRegistration = cancellationToken.Register (() => {
@@ -608,13 +644,13 @@ internal Task WriteRequestContentToOutputInternal (HttpRequestMessage request, H
  if (!IsErrorStatusCode (statusCode)) {
  if (Logger.LogNet)
  Logger.Log (LogLevel.Info, LOG_APP, $"Reading...");
- ret.Content = GetContent (httpConnection, httpConnection.InputStream!);
+ ret.Content = GetContent (httpConnection, httpConnection.InputStream!, contentState);
  } else {
  if (Logger.LogNet)
  Logger.Log (LogLevel.Info, LOG_APP, $"Status code is {statusCode}, reading...");
  // For 400 >= response code <= 599 the Java client throws the FileNotFound exception when attempting to read from the input stream.
  // Instead we try to read the error stream and return an empty string if the error stream isn't readable.
- ret.Content = GetErrorContent (httpConnection, new StringContent (String.Empty, Encoding.ASCII));
+ ret.Content = GetErrorContent (httpConnection, new StringContent (String.Empty, Encoding.ASCII), contentState);
  }
 
  bool disposeRet;
@@ -633,7 +669,7 @@ internal Task WriteRequestContentToOutputInternal (HttpRequestMessage request, H
  }
  }
 
- CopyHeaders (httpConnection, ret);
+ CopyHeaders (httpConnection, ret, contentState);
  ParseCookies (ret, connectionUri);
 
  if (disposeRet) {
@@ -661,8 +697,8 @@ internal Task WriteRequestContentToOutputInternal (HttpRequestMessage request, H
  // We return the body of the response too, but the Java client will throw
  // a FileNotFound exception if we attempt to access the input stream.
  // Instead we try to read the error stream and return an default message if the error stream isn't readable.
- ret.Content = GetErrorContent (httpConnection, new StringContent ("Unauthorized", Encoding.ASCII));
- CopyHeaders (httpConnection, ret);
+ ret.Content = GetErrorContent (httpConnection, new StringContent ("Unauthorized", Encoding.ASCII), contentState);
+ CopyHeaders (httpConnection, ret, contentState);
 
  if (ret.Headers.WwwAuthenticate != null) {
  ProxyAuthenticationRequested = false;
@@ -676,37 +712,65 @@ internal Task WriteRequestContentToOutputInternal (HttpRequestMessage request, H
  return ret;
  }
 
- CopyHeaders (httpConnection, ret);
+ CopyHeaders (httpConnection, ret, contentState);
  ParseCookies (ret, connectionUri);
 
  if (Logger.LogNet)
  Logger.Log (LogLevel.Info, LOG_APP, $"Returning");
  return ret;
  }
 
- HttpContent GetErrorContent (HttpURLConnection httpConnection, HttpContent fallbackContent)
+ HttpContent GetErrorContent (HttpURLConnection httpConnection, HttpContent fallbackContent, ContentState contentState)
  {
  var contentStream = httpConnection.ErrorStream;
 
  if (contentStream != null) {
- return GetContent (httpConnection, contentStream);
+ return GetContent (httpConnection, contentStream, contentState);
  }
 
  return fallbackContent;
  }
 
- HttpContent GetContent (URLConnection httpConnection, Stream contentStream)
+ Stream GetDecompressionWrapper (URLConnection httpConnection, Stream inputStream, ContentState contentState)
  {
- Stream inputStream = new BufferedStream (contentStream);
- if (decompress_here) {
- var encodings = httpConnection.ContentEncoding?.Split (',');
- if (encodings != null) {
- if (encodings.Contains (GZIP_ENCODING, StringComparer.OrdinalIgnoreCase))
- inputStream = new GZipStream (inputStream, CompressionMode.Decompress);
- else if (encodings.Contains (DEFLATE_ENCODING, StringComparer.OrdinalIgnoreCase))
- inputStream = new DeflateStream (inputStream, CompressionMode.Decompress);
+ contentState.Reset ();
+ if (!decompress_here || String.IsNullOrEmpty (httpConnection.ContentEncoding)) {
+ return inputStream;
+ }
+
+ var encodings = new HashSet<string> (httpConnection.ContentEncoding?.Split (','), StringComparer.OrdinalIgnoreCase);
+ Stream? ret = null;
+ string? supportedEncoding = null;
+ if (encodings.Contains (GZIP_ENCODING)) {
+ supportedEncoding = GZIP_ENCODING;
+ ret = new GZipStream (inputStream, CompressionMode.Decompress);
+ } else if (encodings.Contains (DEFLATE_ENCODING)) {
+ supportedEncoding = DEFLATE_ENCODING;
+ ret = new DeflateStream (inputStream, CompressionMode.Decompress);
+ }
+#if NETCOREAPP
+ else if (encodings.Contains (BROTLI_ENCODING)) {
+ supportedEncoding = BROTLI_ENCODING;
+ ret = new BrotliStream (inputStream, CompressionMode.Decompress);
+ }
+#endif
+ if (!String.IsNullOrEmpty (supportedEncoding)) {
+ contentState.RemoveContentLengthHeader = true;
+
+ encodings.Remove (supportedEncoding!);
+ if (encodings.Count == 0) {
+ contentState.RemoveContentEncodingHeader = true;
+ } else {
+ contentState.NewContentEncodingHeaderValue = new List<string> (encodings);
  }
  }
+
+ return ret ?? inputStream;
+ }
+
+ HttpContent GetContent (URLConnection httpConnection, Stream contentStream, ContentState contentState)
+ {
+ Stream inputStream = GetDecompressionWrapper (httpConnection, new BufferedStream (contentStream), contentState);
  return new StreamContent (inputStream);
  }
 
@@ -881,9 +945,13 @@ void ParseCookies (AndroidHttpResponseMessage ret, Uri connectionUri)
  }
  }
 
- void CopyHeaders (HttpURLConnection httpConnection, HttpResponseMessage response)
+ void CopyHeaders (HttpURLConnection httpConnection, HttpResponseMessage response, ContentState contentState)
  {
  var headers = httpConnection.HeaderFields;
+ bool removeContentLength = contentState.RemoveContentLengthHeader ?? false;
+ bool removeContentEncoding = contentState.RemoveContentEncodingHeader ?? false;
+ bool setNewContentEncodingValue = !removeContentEncoding && contentState.NewContentEncodingHeaderValue != null && contentState.NewContentEncodingHeaderValue.Count > 0;
+
  foreach (var key in headers!.Keys) {
  if (key == null) // First header entry has null key, it corresponds to the response message
  continue;
@@ -895,8 +963,25 @@ void CopyHeaders (HttpURLConnection httpConnection, HttpResponseMessage response
  } else {
  item_headers = response.Headers;
  }
- item_headers.TryAddWithoutValidation (key, headers [key]);
+
+ IEnumerable<string> values = headers [key];
+ if (removeContentLength && String.Compare (ContentLengthHeaderName, key, StringComparison.OrdinalIgnoreCase) == 0) {
+ removeContentLength = false;
+ continue;
+ }
+
+ if ((removeContentEncoding || setNewContentEncodingValue) && String.Compare (ContentEncodingHeaderName, key, StringComparison.OrdinalIgnoreCase) == 0) {
+ if (removeContentEncoding) {
+ removeContentEncoding = false;
+ continue;
+ }
+
+ setNewContentEncodingValue = false;
+ values = contentState.NewContentEncodingHeaderValue!;
+ }
+ item_headers.TryAddWithoutValidation (key, values);
  }
+ contentState.Reset ();
  }
 
  /// <summary>
@@ -1006,19 +1091,24 @@ void AppendEncoding (string encoding, ref List <string>? list)
  List <string>? accept_encoding = null;
 
  decompress_here = false;
- if ((AutomaticDecompression & DecompressionMethods.GZip) != 0) {
- AppendEncoding (GZIP_ENCODING, ref accept_encoding);
- decompress_here = true;
- }
-
- if ((AutomaticDecompression & DecompressionMethods.Deflate) != 0) {
- AppendEncoding (DEFLATE_ENCODING, ref accept_encoding);
- decompress_here = true;
- }
-
  if (AutomaticDecompression == DecompressionMethods.None) {
- accept_encoding?.Clear ();
  AppendEncoding (IDENTITY_ENCODING, ref accept_encoding); // Turns off compression for the Java client
+ } else {
+ if ((AutomaticDecompression & DecompressionMethods.GZip) != 0) {
+ AppendEncoding (GZIP_ENCODING, ref accept_encoding);
+ decompress_here = true;
+ }
+
+ if ((AutomaticDecompression & DecompressionMethods.Deflate) != 0) {
+ AppendEncoding (DEFLATE_ENCODING, ref accept_encoding);
+ decompress_here = true;
+ }
+#if NETCOREAPP
+ if ((AutomaticDecompression & DecompressionMethods.Brotli) != 0) {
+ AppendEncoding (BROTLI_ENCODING, ref accept_encoding);
+ decompress_here = true;
+ }
+#endif
  }
 
  if (accept_encoding?.Count > 0)