From 83a94f9e4030cf608ffb53592b937bbe7e7a4307 Mon Sep 17 00:00:00 2001
From: Don <don.j.olmstead@gmail.com>
Date: Thu, 21 Sep 2017 13:43:51 -0700
Subject: [PATCH 01/20] Update MultipartFile

---
 lib/http.dart               |  1 +
 lib/src/multipart_file.dart | 56 +++++++++++++++++--------------------
 2 files changed, 27 insertions(+), 30 deletions(-)

diff --git a/lib/http.dart b/lib/http.dart
index 2728e1994b..4736abf2da 100644
--- a/lib/http.dart
+++ b/lib/http.dart
@@ -16,6 +16,7 @@ export 'src/exception.dart';
 export 'src/handler.dart';
 export 'src/io_client.dart';
 export 'src/middleware.dart';
+export 'src/multipart_file.dart';
 export 'src/pipeline.dart';
 export 'src/request.dart';
 export 'src/response.dart';
diff --git a/lib/src/multipart_file.dart b/lib/src/multipart_file.dart
index da4bface78..0736886bae 100644
--- a/lib/src/multipart_file.dart
+++ b/lib/src/multipart_file.dart
@@ -7,20 +7,23 @@ import 'dart:convert';
 import 'dart:io';
 
 import 'package:async/async.dart';
+import 'package:collection/collection.dart';
 import 'package:http_parser/http_parser.dart';
 import 'package:path/path.dart' as path;
 
-import 'byte_stream.dart';
 import 'utils.dart';
 
 /// A file to be uploaded as part of a [MultipartRequest]. This doesn't need to
 /// correspond to a physical file.
 class MultipartFile {
+  /// The stream that will emit the file's contents.
+  Stream<List<int>> _stream;
+
   /// The name of the form field for the file.
   final String field;
 
   /// The size of the file in bytes. This must be known in advance, even if this
-  /// file is created from a [ByteStream].
+  /// file is created from a [Stream].
   final int length;
 
   /// The basename of the file. May be null.
@@ -29,13 +32,6 @@ class MultipartFile {
   /// The content-type of the file. Defaults to `application/octet-stream`.
   final MediaType contentType;
 
-  /// The stream that will emit the file's contents.
-  final ByteStream _stream;
-
-  /// Whether [finalize] has been called.
-  bool get isFinalized => _isFinalized;
-  bool _isFinalized = false;
-
   /// Creates a new [MultipartFile] from a chunked [Stream] of bytes. The length
   /// of the file in bytes must be known in advance. If it's not, read the data
   /// from the stream and use [MultipartFile.fromBytes] instead.
@@ -44,9 +40,10 @@ class MultipartFile {
   /// future may be inferred from [filename].
   MultipartFile(this.field, Stream<List<int>> stream, this.length,
       {this.filename, MediaType contentType})
-    : this._stream = toByteStream(stream),
-      this.contentType = contentType != null ? contentType :
-          new MediaType("application", "octet-stream");
+      : this._stream = stream,
+        this.contentType = contentType != null
+            ? contentType
+            : new MediaType("application", "octet-stream");
 
   /// Creates a new [MultipartFile] from a byte array.
   ///
@@ -54,10 +51,9 @@ class MultipartFile {
   /// future may be inferred from [filename].
   factory MultipartFile.fromBytes(String field, List<int> value,
       {String filename, MediaType contentType}) {
-    var stream = new ByteStream.fromBytes(value);
+    var stream = new Stream.fromIterable([DelegatingList.typed(value)]);
     return new MultipartFile(field, stream, value.length,
-        filename: filename,
-        contentType: contentType);
+        filename: filename, contentType: contentType);
   }
 
   /// Creates a new [MultipartFile] from a string.
@@ -68,14 +64,13 @@ class MultipartFile {
   /// the future may be inferred from [filename].
   factory MultipartFile.fromString(String field, String value,
       {String filename, MediaType contentType}) {
-    contentType = contentType == null ? new MediaType("text", "plain")
-                                      : contentType;
+    contentType =
+        contentType == null ? new MediaType("text", "plain") : contentType;
     var encoding = encodingForCharset(contentType.parameters['charset'], UTF8);
     contentType = contentType.change(parameters: {'charset': encoding.name});
 
     return new MultipartFile.fromBytes(field, encoding.encode(value),
-        filename: filename,
-        contentType: contentType);
+        filename: filename, contentType: contentType);
   }
 
   // TODO(nweiz): Infer the content-type from the filename.
@@ -92,20 +87,21 @@ class MultipartFile {
     if (filename == null) filename = path.basename(filePath);
     var file = new File(filePath);
     var length = await file.length();
-    var stream = new ByteStream(DelegatingStream.typed(file.openRead()));
+    var stream = DelegatingStream.typed(file.openRead());
     return new MultipartFile(field, stream, length,
-        filename: filename,
-        contentType: contentType);
+        filename: filename, contentType: contentType);
   }
 
-  // Finalizes the file in preparation for it being sent as part of a
-  // [MultipartRequest]. This returns a [ByteStream] that should emit the body
-  // of the file. The stream may be closed to indicate an empty file.
-  ByteStream finalize() {
-    if (isFinalized) {
-      throw new StateError("Can't finalize a finalized MultipartFile.");
+  /// Returns a [Stream] representing the file.
+  ///
+  /// Can only be called once.
+  Stream<List<int>> read() {
+    if (_stream == null) {
+      throw new StateError("The 'read' method can only be called once on a "
+          "http.MultipartFile object.");
     }
-    _isFinalized = true;
-    return _stream;
+    var stream = _stream;
+    _stream = null;
+    return stream;
   }
 }

From a94906307c555fd0b2ebb4f1433eaf23303d4d74 Mon Sep 17 00:00:00 2001
From: Don <don.j.olmstead@gmail.com>
Date: Thu, 21 Sep 2017 13:44:23 -0700
Subject: [PATCH 02/20] Update MultipartRequest

---
 lib/src/boundary_characters.dart |  19 +++
 lib/src/multipart_request.dart   | 233 ++++++++++++++-----------------
 lib/src/request.dart             |  15 ++
 3 files changed, 141 insertions(+), 126 deletions(-)

diff --git a/lib/src/boundary_characters.dart b/lib/src/boundary_characters.dart
index cc5742a30a..249acbd047 100644
--- a/lib/src/boundary_characters.dart
+++ b/lib/src/boundary_characters.dart
@@ -2,6 +2,8 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+import 'dart:math';
+
 /// All character codes that are valid in multipart boundaries. This is the
 /// intersection of the characters allowed in the `bcharsnospace` production
 /// defined in [RFC 2046][] and those allowed in the `token` production
@@ -16,3 +18,20 @@ const List<int> BOUNDARY_CHARACTERS = const <int>[
   107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121,
   122
 ];
+
+/// The total length of the multipart boundaries used when building the
+/// request body. According to http://tools.ietf.org/html/rfc1341.html, this
+/// can't be longer than 70.
+const int BOUNDARY_LENGTH = 70;
+
+final Random _random = new Random();
+
+/// Returns a randomly-generated multipart boundary string
+String boundaryString() {
+  var prefix = "dart-http-boundary-";
+  var list = new List<int>.generate(BOUNDARY_LENGTH - prefix.length,
+          (index) =>
+      BOUNDARY_CHARACTERS[_random.nextInt(BOUNDARY_CHARACTERS.length)],
+      growable: false);
+  return "$prefix${new String.fromCharCodes(list)}";
+}
diff --git a/lib/src/multipart_request.dart b/lib/src/multipart_request.dart
index 8132f80924..07712910d8 100644
--- a/lib/src/multipart_request.dart
+++ b/lib/src/multipart_request.dart
@@ -4,162 +4,143 @@
 
 import 'dart:async';
 import 'dart:convert';
-import 'dart:math';
 
-import 'base_request.dart';
-import 'boundary_characters.dart';
-import 'byte_stream.dart';
+import 'body.dart';
 import 'multipart_file.dart';
 import 'utils.dart';
 
 final _newlineRegExp = new RegExp(r"\r\n|\r|\n");
 
-/// A `multipart/form-data` request. Such a request has both string [fields],
-/// which function as normal form fields, and (potentially streamed) binary
-/// [files].
-///
-/// This request automatically sets the Content-Type header to
-/// `multipart/form-data`. This value will override any value set by the user.
-///
-///     var uri = Uri.parse("http://pub.dartlang.org/packages/create");
-///     var request = new http.MultipartRequest("POST", url);
-///     request.fields['user'] = 'nweiz@google.com';
-///     request.files.add(new http.MultipartFile.fromFile(
-///         'package',
-///         new File('build/package.tar.gz'),
-///         contentType: new MediaType('application', 'x-tar'));
-///     request.send().then((response) {
-///       if (response.statusCode == 200) print("Uploaded!");
-///     });
-class MultipartRequest extends BaseRequest {
-  /// The total length of the multipart boundaries used when building the
-  /// request body. According to http://tools.ietf.org/html/rfc1341.html, this
-  /// can't be longer than 70.
-  static const int _BOUNDARY_LENGTH = 70;
-
-  static final Random _random = new Random();
-
-  /// The form fields to send for this request.
-  final Map<String, String> fields;
-
-  /// The private version of [files].
-  final List<MultipartFile> _files;
-
-  /// Creates a new [MultipartRequest].
-  MultipartRequest(String method, Uri url)
-    : fields = {},
-      _files = <MultipartFile>[],
-      super(method, url);
-
-  /// The list of files to upload for this request.
-  List<MultipartFile> get files => _files;
-
-  /// The total length of the request body, in bytes. This is calculated from
-  /// [fields] and [files] and cannot be set manually.
-  int get contentLength {
-    var length = 0;
-
-    fields.forEach((name, value) {
-      length += "--".length + _BOUNDARY_LENGTH + "\r\n".length +
-          UTF8.encode(_headerForField(name, value)).length +
-          UTF8.encode(value).length + "\r\n".length;
-    });
-
-    for (var file in _files) {
-      length += "--".length + _BOUNDARY_LENGTH + "\r\n".length +
-          UTF8.encode(_headerForFile(file)).length +
-          file.length + "\r\n".length;
-    }
-
-    return length + "--".length + _BOUNDARY_LENGTH + "--\r\n".length;
-  }
-
-  void set contentLength(int value) {
-    throw new UnsupportedError("Cannot set the contentLength property of "
-        "multipart requests.");
-  }
-
-  /// Freezes all mutable fields and returns a single-subscription [ByteStream]
-  /// that will emit the request body.
-  ByteStream finalize() {
-    // TODO(nweiz): freeze fields and files
-    var boundary = _boundaryString();
-    headers['content-type'] = 'multipart/form-data; boundary=$boundary';
-    super.finalize();
-
+class MultipartBody implements Body {
+  /// The contents of the message body.
+  ///
+  /// This will be `null` after [read] is called.
+  Stream<List<int>> _stream;
+
+  /// The length of the stream returned by [read].
+  ///
+  /// This is calculated from the fields and files passed into the body.
+  final int contentLength;
+
+  /// Multipart forms do not have an encoding.
+  Encoding get encoding => null;
+
+  /// Creates a [MultipartBody] from the given [fields] and [files].
+  ///
+  /// The [boundary] is used to
+  factory MultipartBody(
+    Map<String, String> fields,
+    List<MultipartFile> files,
+    String boundary,
+  ) {
     var controller = new StreamController<List<int>>(sync: true);
+    var contentLength = 0;
 
     void writeAscii(String string) {
-      controller.add(UTF8.encode(string));
+      controller.add(string.codeUnits);
+      contentLength += string.length;
+    }
+    void writeUtf8(String string) {
+      var encoded = UTF8.encode(string);
+      controller.add(encoded);
+      contentLength += encoded.length;
+    }
+    void writeLine() {
+      controller.add([13, 10]); // \r\n
+      contentLength += 2;
     }
 
-    writeUtf8(String string) => controller.add(UTF8.encode(string));
-    writeLine() => controller.add([13, 10]); // \r\n
-
+    // Write the fields to the stream
     fields.forEach((name, value) {
       writeAscii('--$boundary\r\n');
-      writeAscii(_headerForField(name, value));
+      writeUtf8(_headerForField(name, value));
       writeUtf8(value);
       writeLine();
     });
 
-    Future.forEach(_files, (file) {
-      writeAscii('--$boundary\r\n');
-      writeAscii(_headerForFile(file));
-      return writeStreamToSink(file.finalize(), controller)
-        .then((_) => writeLine());
+    // Iterate over the files to get the length
+    var fileCount = files.length;
+    var fileHeaders = new List<List<int>>(fileCount);
+
+    for (var i = 0; i < fileCount; ++i) {
+      var file = files[i];
+      var header = <int>[];
+      header.addAll('--$boundary\r\n'.codeUnits);
+      header.addAll(UTF8.encode(_headerForFile(file)));
+      contentLength += header.length + file.length + 2;
+      fileHeaders[i] = header;
+    }
+
+    // Ending characters
+    var ending = '--$boundary--\r\n'.codeUnits;
+    contentLength += ending.length;
+
+    // Write the files to the stream
+    //
+    // Future.forEach will ensure that the actions happen in sequence so i is
+    // used to get the fileHeaders
+    var i = 0;
+
+    Future.forEach(files, (file) {
+      assert(files[i] == file);
+      controller.add(fileHeaders[i++]);
+      return writeStreamToSink(file.read(), controller).then((_) => controller.add([13, 10]));
     }).then((_) {
       // TODO(nweiz): pass any errors propagated through this future on to
       // the stream. See issue 3657.
-      writeAscii('--$boundary--\r\n');
+      controller.add(ending);
       controller.close();
     });
 
-    return new ByteStream(controller.stream);
-  }
-
-  /// Returns the header string for a field. The return value is guaranteed to
-  /// contain only ASCII characters.
-  String _headerForField(String name, String value) {
-    var header =
-        'content-disposition: form-data; name="${_browserEncode(name)}"';
-    if (!isPlainAscii(value)) {
-      header = '$header\r\n'
-          'content-type: text/plain; charset=utf-8\r\n'
-          'content-transfer-encoding: binary';
-    }
-    return '$header\r\n\r\n';
+    return new MultipartBody._(controller.stream, contentLength);
   }
 
-  /// Returns the header string for a file. The return value is guaranteed to
-  /// contain only ASCII characters.
-  String _headerForFile(MultipartFile file) {
-    var header = 'content-type: ${file.contentType}\r\n'
-      'content-disposition: form-data; name="${_browserEncode(file.field)}"';
+  MultipartBody._(this._stream, this.contentLength);
 
-    if (file.filename != null) {
-      header = '$header; filename="${_browserEncode(file.filename)}"';
+  /// Returns a [Stream] representing the body.
+  ///
+  /// Can only be called once.
+  Stream<List<int>> read() {
+    if (_stream == null) {
+      throw new StateError("The 'read' method can only be called once on a "
+          "http.Request/http.Response object.");
     }
-    return '$header\r\n\r\n';
+    var stream = _stream;
+    _stream = null;
+    return stream;
   }
+}
 
-  /// Encode [value] in the same way browsers do.
-  String _browserEncode(String value) {
-    // http://tools.ietf.org/html/rfc2388 mandates some complex encodings for
-    // field names and file names, but in practice user agents seem not to
-    // follow this at all. Instead, they URL-encode `\r`, `\n`, and `\r\n` as
-    // `\r\n`; URL-encode `"`; and do nothing else (even for `%` or non-ASCII
-    // characters). We follow their behavior.
-    return value.replaceAll(_newlineRegExp, "%0D%0A").replaceAll('"', "%22");
+/// Returns the header string for a field.
+String _headerForField(String name, String value) {
+  var header =
+      'content-disposition: form-data; name="${_browserEncode(name)}"';
+  if (!isPlainAscii(value)) {
+    header = '$header\r\n'
+        'content-type: text/plain; charset=utf-8\r\n'
+        'content-transfer-encoding: binary';
   }
+  return '$header\r\n\r\n';
+}
 
-  /// Returns a randomly-generated multipart boundary string
-  String _boundaryString() {
-    var prefix = "dart-http-boundary-";
-    var list = new List<int>.generate(_BOUNDARY_LENGTH - prefix.length,
-        (index) =>
-            BOUNDARY_CHARACTERS[_random.nextInt(BOUNDARY_CHARACTERS.length)],
-        growable: false);
-    return "$prefix${new String.fromCharCodes(list)}";
+/// Returns the header string for a file. The return value is guaranteed to
+/// contain only ASCII characters.
+String _headerForFile(MultipartFile file) {
+  var header = 'content-type: ${file.contentType}\r\n'
+      'content-disposition: form-data; name="${_browserEncode(file.field)}"';
+
+  if (file.filename != null) {
+    header = '$header; filename="${_browserEncode(file.filename)}"';
   }
+  return '$header\r\n\r\n';
+}
+
+/// Encode [value] in the same way browsers do.
+String _browserEncode(String value) {
+  // http://tools.ietf.org/html/rfc2388 mandates some complex encodings for
+  // field names and file names, but in practice user agents seem not to
+  // follow this at all. Instead, they URL-encode `\r`, `\n`, and `\r\n` as
+  // `\r\n`; URL-encode `"`; and do nothing else (even for `%` or non-ASCII
+  // characters). We follow their behavior.
+  return value.replaceAll(_newlineRegExp, "%0D%0A").replaceAll('"', "%22");
 }
diff --git a/lib/src/request.dart b/lib/src/request.dart
index f49c5b9f16..89b5d33bbb 100644
--- a/lib/src/request.dart
+++ b/lib/src/request.dart
@@ -4,7 +4,10 @@
 
 import 'dart:convert';
 
+import 'boundary_characters.dart';
 import 'message.dart';
+import 'multipart_file.dart';
+import 'multipart_request.dart';
 import 'utils.dart';
 
 /// Represents an HTTP request to be sent to a server.
@@ -130,6 +133,18 @@ class Request extends Message {
       {Map<String, String> headers, Map<String, Object> context})
       : this('DELETE', url, headers: headers, context: context);
 
+  factory Request.multipart(url, {Map<String, String> headers, Map<String, Object> context, Map<String, String> fields, List<MultipartFile> files,}) {
+    fields ??= <String, String>{};
+    files ??= <MultipartFile>[];
+
+    var boundary = boundaryString();
+
+    headers ??= <String, String>{};
+    headers['content-type'] = 'multipart/form-data; boundary=$boundary';
+
+    return new Request._('POST', url, new MultipartBody(fields, files, boundary), null, headers, context,);
+  }
+
   Request._(this.method, this.url,
       body,
       Encoding encoding,

From 4f75ac7457be16515b6c2a81f18aed422e54858c Mon Sep 17 00:00:00 2001
From: Don <don.j.olmstead@gmail.com>
Date: Wed, 27 Sep 2017 18:30:19 -0700
Subject: [PATCH 03/20] Fixing some nits

---
 lib/src/boundary_characters.dart | 37 ----------------
 lib/src/multipart_file.dart      | 19 +++++---
 lib/src/multipart_request.dart   | 75 ++++++++++++++++----------------
 lib/src/request.dart             | 40 ++++++++++++++++-
 4 files changed, 88 insertions(+), 83 deletions(-)
 delete mode 100644 lib/src/boundary_characters.dart

diff --git a/lib/src/boundary_characters.dart b/lib/src/boundary_characters.dart
deleted file mode 100644
index 249acbd047..0000000000
--- a/lib/src/boundary_characters.dart
+++ /dev/null
@@ -1,37 +0,0 @@
-// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-
-import 'dart:math';
-
-/// All character codes that are valid in multipart boundaries. This is the
-/// intersection of the characters allowed in the `bcharsnospace` production
-/// defined in [RFC 2046][] and those allowed in the `token` production
-/// defined in [RFC 1521][].
-///
-/// [RFC 2046]: http://tools.ietf.org/html/rfc2046#section-5.1.1.
-/// [RFC 1521]: https://tools.ietf.org/html/rfc1521#section-4
-const List<int> BOUNDARY_CHARACTERS = const <int>[
-  43, 95, 45, 46, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57,
-  65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83,
-  84, 85, 86, 87, 88, 89, 90, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106,
-  107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121,
-  122
-];
-
-/// The total length of the multipart boundaries used when building the
-/// request body. According to http://tools.ietf.org/html/rfc1341.html, this
-/// can't be longer than 70.
-const int BOUNDARY_LENGTH = 70;
-
-final Random _random = new Random();
-
-/// Returns a randomly-generated multipart boundary string
-String boundaryString() {
-  var prefix = "dart-http-boundary-";
-  var list = new List<int>.generate(BOUNDARY_LENGTH - prefix.length,
-          (index) =>
-      BOUNDARY_CHARACTERS[_random.nextInt(BOUNDARY_CHARACTERS.length)],
-      growable: false);
-  return "$prefix${new String.fromCharCodes(list)}";
-}
diff --git a/lib/src/multipart_file.dart b/lib/src/multipart_file.dart
index 0736886bae..31675047dd 100644
--- a/lib/src/multipart_file.dart
+++ b/lib/src/multipart_file.dart
@@ -22,19 +22,24 @@ class MultipartFile {
   /// The name of the form field for the file.
   final String field;
 
-  /// The size of the file in bytes. This must be known in advance, even if this
-  /// file is created from a [Stream].
+  /// The size of the file in bytes.
+  ///
+  /// This must be known in advance, even if this file is created from a
+  /// [Stream].
   final int length;
 
   /// The basename of the file. May be null.
   final String filename;
 
-  /// The content-type of the file. Defaults to `application/octet-stream`.
+  /// The content-type of the file.
+  ///
+  /// Defaults to `application/octet-stream`.
   final MediaType contentType;
 
-  /// Creates a new [MultipartFile] from a chunked [Stream] of bytes. The length
-  /// of the file in bytes must be known in advance. If it's not, read the data
-  /// from the stream and use [MultipartFile.fromBytes] instead.
+  /// Creates a new [MultipartFile] from a chunked [Stream] of bytes.
+  ///
+  /// The length of the file in bytes must be known in advance. If it's not,
+  /// read the data from the stream and use [MultipartFile.fromBytes] instead.
   ///
   /// [contentType] currently defaults to `application/octet-stream`, but in the
   /// future may be inferred from [filename].
@@ -92,7 +97,7 @@ class MultipartFile {
         filename: filename, contentType: contentType);
   }
 
-  /// Returns a [Stream] representing the file.
+  /// Returns a [Stream] representing the contents of the file.
   ///
   /// Can only be called once.
   Stream<List<int>> read() {
diff --git a/lib/src/multipart_request.dart b/lib/src/multipart_request.dart
index 07712910d8..2062f32af3 100644
--- a/lib/src/multipart_request.dart
+++ b/lib/src/multipart_request.dart
@@ -4,6 +4,7 @@
 
 import 'dart:async';
 import 'dart:convert';
+import 'dart:math';
 
 import 'body.dart';
 import 'multipart_file.dart';
@@ -28,11 +29,9 @@ class MultipartBody implements Body {
   /// Creates a [MultipartBody] from the given [fields] and [files].
   ///
   /// The [boundary] is used to
-  factory MultipartBody(
-    Map<String, String> fields,
-    List<MultipartFile> files,
-    String boundary,
-  ) {
+  factory MultipartBody(Map<String, String> fields,
+      List<MultipartFile> files,
+      String boundary,) {
     var controller = new StreamController<List<int>>(sync: true);
     var contentLength = 0;
 
@@ -84,7 +83,8 @@ class MultipartBody implements Body {
     Future.forEach(files, (file) {
       assert(files[i] == file);
       controller.add(fileHeaders[i++]);
-      return writeStreamToSink(file.read(), controller).then((_) => controller.add([13, 10]));
+      return writeStreamToSink(file.read(), controller).then((_) =>
+          controller.add([13, 10]));
     }).then((_) {
       // TODO(nweiz): pass any errors propagated through this future on to
       // the stream. See issue 3657.
@@ -109,38 +109,39 @@ class MultipartBody implements Body {
     _stream = null;
     return stream;
   }
-}
-
-/// Returns the header string for a field.
-String _headerForField(String name, String value) {
-  var header =
-      'content-disposition: form-data; name="${_browserEncode(name)}"';
-  if (!isPlainAscii(value)) {
-    header = '$header\r\n'
-        'content-type: text/plain; charset=utf-8\r\n'
-        'content-transfer-encoding: binary';
+
+  /// Returns the header string for a field.
+  static String _headerForField(String name, String value) {
+    var header =
+        'content-disposition: form-data; name="${_browserEncode(name)}"';
+    if (!isPlainAscii(value)) {
+      header = '$header\r\n'
+          'content-type: text/plain; charset=utf-8\r\n'
+          'content-transfer-encoding: binary';
+    }
+    return '$header\r\n\r\n';
   }
-  return '$header\r\n\r\n';
-}
 
-/// Returns the header string for a file. The return value is guaranteed to
-/// contain only ASCII characters.
-String _headerForFile(MultipartFile file) {
-  var header = 'content-type: ${file.contentType}\r\n'
-      'content-disposition: form-data; name="${_browserEncode(file.field)}"';
+  /// Returns the header string for a file.
+  ///
+  /// The return value is guaranteed to contain only ASCII characters.
+  static String _headerForFile(MultipartFile file) {
+    var header = 'content-type: ${file.contentType}\r\n'
+        'content-disposition: form-data; name="${_browserEncode(file.field)}"';
+
+    if (file.filename != null) {
+      header = '$header; filename="${_browserEncode(file.filename)}"';
+    }
+    return '$header\r\n\r\n';
+  }
 
-  if (file.filename != null) {
-    header = '$header; filename="${_browserEncode(file.filename)}"';
+  /// Encode [value] in the same way browsers do.
+  static String _browserEncode(String value) {
+    // http://tools.ietf.org/html/rfc2388 mandates some complex encodings for
+    // field names and file names, but in practice user agents seem not to
+    // follow this at all. Instead, they URL-encode `\r`, `\n`, and `\r\n` as
+    // `\r\n`; URL-encode `"`; and do nothing else (even for `%` or non-ASCII
+    // characters). We follow their behavior.
+    return value.replaceAll(_newlineRegExp, "%0D%0A").replaceAll('"', "%22");
   }
-  return '$header\r\n\r\n';
-}
-
-/// Encode [value] in the same way browsers do.
-String _browserEncode(String value) {
-  // http://tools.ietf.org/html/rfc2388 mandates some complex encodings for
-  // field names and file names, but in practice user agents seem not to
-  // follow this at all. Instead, they URL-encode `\r`, `\n`, and `\r\n` as
-  // `\r\n`; URL-encode `"`; and do nothing else (even for `%` or non-ASCII
-  // characters). We follow their behavior.
-  return value.replaceAll(_newlineRegExp, "%0D%0A").replaceAll('"', "%22");
-}
+}
\ No newline at end of file
diff --git a/lib/src/request.dart b/lib/src/request.dart
index 89b5d33bbb..4694d577fe 100644
--- a/lib/src/request.dart
+++ b/lib/src/request.dart
@@ -3,8 +3,8 @@
 // BSD-style license that can be found in the LICENSE file.
 
 import 'dart:convert';
+import 'dart:math';
 
-import 'boundary_characters.dart';
 import 'message.dart';
 import 'multipart_file.dart';
 import 'multipart_request.dart';
@@ -137,7 +137,7 @@ class Request extends Message {
     fields ??= <String, String>{};
     files ??= <MultipartFile>[];
 
-    var boundary = boundaryString();
+    var boundary = _boundaryString();
 
     headers ??= <String, String>{};
     headers['content-type'] = 'multipart/form-data; boundary=$boundary';
@@ -178,4 +178,40 @@ class Request extends Message {
         updatedHeaders,
         updatedContext);
   }
+
+
+  /// All character codes that are valid in multipart boundaries.
+  ///
+  /// This is the intersection of the characters allowed in the `bcharsnospace`
+  /// production defined in [RFC 2046][] and those allowed in the `token`
+  /// production defined in [RFC 1521][].
+  ///
+  /// [RFC 2046]: http://tools.ietf.org/html/rfc2046#section-5.1.1.
+  /// [RFC 1521]: https://tools.ietf.org/html/rfc1521#section-4
+  static const List<int> _boundaryCharacters = const <int>[
+    43, 95, 45, 46, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57,
+    65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83,
+    84, 85, 86, 87, 88, 89, 90, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106,
+    107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121,
+    122
+  ];
+
+  /// The total length of the multipart boundaries used when building the
+  /// request body.
+  ///
+  /// According to http://tools.ietf.org/html/rfc1341.html, this can't be longer
+  /// than 70.
+  static const int _boundaryLength = 70;
+
+  static final Random _random = new Random();
+
+  /// Returns a randomly-generated multipart boundary string
+  static String _boundaryString() {
+    var prefix = "dart-http-boundary-";
+    var list = new List<int>.generate(_boundaryLength - prefix.length,
+            (index) =>
+        _boundaryCharacters[_random.nextInt(_boundaryCharacters.length)],
+        growable: false);
+    return "$prefix${new String.fromCharCodes(list)}";
+  }
 }

From 8592a0ed20b2e3204de1fb0312ac532720011e2f Mon Sep 17 00:00:00 2001
From: Don <don.j.olmstead@gmail.com>
Date: Wed, 27 Sep 2017 18:45:28 -0700
Subject: [PATCH 04/20] Additional nits

---
 lib/src/multipart_request.dart | 18 +++++++++---------
 lib/src/request.dart           |  2 +-
 2 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/lib/src/multipart_request.dart b/lib/src/multipart_request.dart
index 2062f32af3..2aceb08576 100644
--- a/lib/src/multipart_request.dart
+++ b/lib/src/multipart_request.dart
@@ -4,14 +4,11 @@
 
 import 'dart:async';
 import 'dart:convert';
-import 'dart:math';
 
 import 'body.dart';
 import 'multipart_file.dart';
 import 'utils.dart';
 
-final _newlineRegExp = new RegExp(r"\r\n|\r|\n");
-
 class MultipartBody implements Body {
   /// The contents of the message body.
   ///
@@ -49,7 +46,7 @@ class MultipartBody implements Body {
       contentLength += 2;
     }
 
-    // Write the fields to the stream
+    // Write the fields to the stream.
     fields.forEach((name, value) {
       writeAscii('--$boundary\r\n');
       writeUtf8(_headerForField(name, value));
@@ -57,7 +54,8 @@ class MultipartBody implements Body {
       writeLine();
     });
 
-    // Iterate over the files to get the length
+    // Iterate over the files to get the length and compute the headers ahead
+    // time so the length can be synchronously accessed.
     var fileCount = files.length;
     var fileHeaders = new List<List<int>>(fileCount);
 
@@ -70,14 +68,14 @@ class MultipartBody implements Body {
       fileHeaders[i] = header;
     }
 
-    // Ending characters
+    // Ending characters.
     var ending = '--$boundary--\r\n'.codeUnits;
     contentLength += ending.length;
 
-    // Write the files to the stream
+    // Write the files to the stream.
     //
     // Future.forEach will ensure that the actions happen in sequence so i is
-    // used to get the fileHeaders
+    // used to get the fileHeaders.
     var i = 0;
 
     Future.forEach(files, (file) {
@@ -135,6 +133,8 @@ class MultipartBody implements Body {
     return '$header\r\n\r\n';
   }
 
+  static final _newlineRegExp = new RegExp(r"\r\n|\r|\n");
+
   /// Encode [value] in the same way browsers do.
   static String _browserEncode(String value) {
     // http://tools.ietf.org/html/rfc2388 mandates some complex encodings for
@@ -144,4 +144,4 @@ class MultipartBody implements Body {
     // characters). We follow their behavior.
     return value.replaceAll(_newlineRegExp, "%0D%0A").replaceAll('"', "%22");
   }
-}
\ No newline at end of file
+}
diff --git a/lib/src/request.dart b/lib/src/request.dart
index 4694d577fe..bb691a2cc3 100644
--- a/lib/src/request.dart
+++ b/lib/src/request.dart
@@ -133,7 +133,7 @@ class Request extends Message {
       {Map<String, String> headers, Map<String, Object> context})
       : this('DELETE', url, headers: headers, context: context);
 
-  factory Request.multipart(url, {Map<String, String> headers, Map<String, Object> context, Map<String, String> fields, List<MultipartFile> files,}) {
+  factory Request.multipart(url, {Map<String, String> headers, Map<String, Object> context, Map<String, String> fields, Iterable<MultipartFile> files}) {
     fields ??= <String, String>{};
     files ??= <MultipartFile>[];
 

From 19dcfde96c1a558ec0df0555c31395f0a43205d1 Mon Sep 17 00:00:00 2001
From: Don <don.j.olmstead@gmail.com>
Date: Wed, 27 Sep 2017 18:49:49 -0700
Subject: [PATCH 05/20] Formatting

---
 lib/src/request.dart | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/lib/src/request.dart b/lib/src/request.dart
index bb691a2cc3..fbfeb0a7a0 100644
--- a/lib/src/request.dart
+++ b/lib/src/request.dart
@@ -133,7 +133,11 @@ class Request extends Message {
       {Map<String, String> headers, Map<String, Object> context})
       : this('DELETE', url, headers: headers, context: context);
 
-  factory Request.multipart(url, {Map<String, String> headers, Map<String, Object> context, Map<String, String> fields, Iterable<MultipartFile> files}) {
+  factory Request.multipart(url,
+      {Map<String, String> headers,
+        Map<String, Object> context,
+        Map<String, String> fields,
+        Iterable<MultipartFile> files}) {
     fields ??= <String, String>{};
     files ??= <MultipartFile>[];
 
@@ -142,7 +146,14 @@ class Request extends Message {
     headers ??= <String, String>{};
     headers['content-type'] = 'multipart/form-data; boundary=$boundary';
 
-    return new Request._('POST', url, new MultipartBody(fields, files, boundary), null, headers, context,);
+    return new Request._(
+      'POST',
+      url,
+      new MultipartBody(fields, files, boundary),
+      null,
+      headers,
+      context,
+    );
   }
 
   Request._(this.method, this.url,

From 69f6d956d6a09b10a870ec2942e653522c5ca15e Mon Sep 17 00:00:00 2001
From: Don <don.j.olmstead@gmail.com>
Date: Wed, 27 Sep 2017 19:21:39 -0700
Subject: [PATCH 06/20] Rename

---
 lib/src/{multipart_request.dart => multipart_body.dart} | 0
 lib/src/request.dart                                    | 2 +-
 2 files changed, 1 insertion(+), 1 deletion(-)
 rename lib/src/{multipart_request.dart => multipart_body.dart} (100%)

diff --git a/lib/src/multipart_request.dart b/lib/src/multipart_body.dart
similarity index 100%
rename from lib/src/multipart_request.dart
rename to lib/src/multipart_body.dart
diff --git a/lib/src/request.dart b/lib/src/request.dart
index fbfeb0a7a0..d056d78868 100644
--- a/lib/src/request.dart
+++ b/lib/src/request.dart
@@ -7,7 +7,7 @@ import 'dart:math';
 
 import 'message.dart';
 import 'multipart_file.dart';
-import 'multipart_request.dart';
+import 'multipart_body.dart';
 import 'utils.dart';
 
 /// Represents an HTTP request to be sent to a server.

From 26e7bf962992dd416ce726d24046c4ad2cda5a00 Mon Sep 17 00:00:00 2001
From: Don <don.j.olmstead@gmail.com>
Date: Thu, 19 Oct 2017 14:04:38 -0700
Subject: [PATCH 07/20] Use updateMap to add content type

---
 lib/src/request.dart | 18 ++++++++----------
 1 file changed, 8 insertions(+), 10 deletions(-)

diff --git a/lib/src/request.dart b/lib/src/request.dart
index d056d78868..6563dfce01 100644
--- a/lib/src/request.dart
+++ b/lib/src/request.dart
@@ -143,17 +143,15 @@ class Request extends Message {
 
     var boundary = _boundaryString();
 
-    headers ??= <String, String>{};
-    headers['content-type'] = 'multipart/form-data; boundary=$boundary';
-
     return new Request._(
-      'POST',
-      url,
-      new MultipartBody(fields, files, boundary),
-      null,
-      headers,
-      context,
-    );
+        'POST',
+        url,
+        new MultipartBody(fields, files, boundary),
+        null,
+        updateMap(headers, <String, String>{
+          'content-type': 'multipart/form-data; boundary=$boundary'
+        }),
+        context);
   }
 
   Request._(this.method, this.url,

From 20afe261de24d97bf484ce5d6d6e3e2bd919b739 Mon Sep 17 00:00:00 2001
From: Don <don.j.olmstead@gmail.com>
Date: Thu, 19 Oct 2017 16:16:03 -0700
Subject: [PATCH 08/20] Add comment to control dartfmt of boundary characters

---
 lib/src/request.dart | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/lib/src/request.dart b/lib/src/request.dart
index 6563dfce01..17dee0bea4 100644
--- a/lib/src/request.dart
+++ b/lib/src/request.dart
@@ -188,7 +188,6 @@ class Request extends Message {
         updatedContext);
   }
 
-
   /// All character codes that are valid in multipart boundaries.
   ///
   /// This is the intersection of the characters allowed in the `bcharsnospace`
@@ -198,10 +197,10 @@ class Request extends Message {
   /// [RFC 2046]: http://tools.ietf.org/html/rfc2046#section-5.1.1.
   /// [RFC 1521]: https://tools.ietf.org/html/rfc1521#section-4
   static const List<int> _boundaryCharacters = const <int>[
-    43, 95, 45, 46, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57,
-    65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83,
-    84, 85, 86, 87, 88, 89, 90, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106,
-    107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121,
+    43, 95, 45, 46, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 65, 66, 67, 68, //
+    69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, //
+    87, 88, 89, 90, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107,     //
+    108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121,   //
     122
   ];
 

From 7788518e72d41be8f11fde8a7aa4858104209a69 Mon Sep 17 00:00:00 2001
From: Don <don.j.olmstead@gmail.com>
Date: Fri, 20 Oct 2017 16:32:23 -0700
Subject: [PATCH 09/20] nits

---
 lib/src/multipart_body.dart |  9 +++++----
 lib/src/multipart_file.dart | 12 +++++-------
 2 files changed, 10 insertions(+), 11 deletions(-)

diff --git a/lib/src/multipart_body.dart b/lib/src/multipart_body.dart
index 2aceb08576..16f7ffd94c 100644
--- a/lib/src/multipart_body.dart
+++ b/lib/src/multipart_body.dart
@@ -27,8 +27,7 @@ class MultipartBody implements Body {
   ///
   /// The [boundary] is used to
   factory MultipartBody(Map<String, String> fields,
-      List<MultipartFile> files,
-      String boundary,) {
+      Iterable<MultipartFile> files, String boundary) {
     var controller = new StreamController<List<int>>(sync: true);
     var contentLength = 0;
 
@@ -36,11 +35,13 @@ class MultipartBody implements Body {
       controller.add(string.codeUnits);
       contentLength += string.length;
     }
+
     void writeUtf8(String string) {
       var encoded = UTF8.encode(string);
       controller.add(encoded);
       contentLength += encoded.length;
     }
+
     void writeLine() {
       controller.add([13, 10]); // \r\n
       contentLength += 2;
@@ -81,8 +82,8 @@ class MultipartBody implements Body {
     Future.forEach(files, (file) {
       assert(files[i] == file);
       controller.add(fileHeaders[i++]);
-      return writeStreamToSink(file.read(), controller).then((_) =>
-          controller.add([13, 10]));
+      return writeStreamToSink(file.read(), controller)
+          .then((_) => controller.add([13, 10]));
     }).then((_) {
       // TODO(nweiz): pass any errors propagated through this future on to
       // the stream. See issue 3657.
diff --git a/lib/src/multipart_file.dart b/lib/src/multipart_file.dart
index 31675047dd..d3cc44398a 100644
--- a/lib/src/multipart_file.dart
+++ b/lib/src/multipart_file.dart
@@ -11,7 +11,7 @@ import 'package:collection/collection.dart';
 import 'package:http_parser/http_parser.dart';
 import 'package:path/path.dart' as path;
 
-import 'utils.dart';
+import 'content_type.dart';
 
 /// A file to be uploaded as part of a [MultipartRequest]. This doesn't need to
 /// correspond to a physical file.
@@ -46,9 +46,8 @@ class MultipartFile {
   MultipartFile(this.field, Stream<List<int>> stream, this.length,
       {this.filename, MediaType contentType})
       : this._stream = stream,
-        this.contentType = contentType != null
-            ? contentType
-            : new MediaType("application", "octet-stream");
+        this.contentType =
+            contentType ?? new MediaType("application", "octet-stream");
 
   /// Creates a new [MultipartFile] from a byte array.
   ///
@@ -69,9 +68,8 @@ class MultipartFile {
   /// the future may be inferred from [filename].
   factory MultipartFile.fromString(String field, String value,
       {String filename, MediaType contentType}) {
-    contentType =
-        contentType == null ? new MediaType("text", "plain") : contentType;
-    var encoding = encodingForCharset(contentType.parameters['charset'], UTF8);
+    contentType ??= new MediaType("text", "plain");
+    var encoding = encodingForMediaType(contentType) ?? UTF8;
     contentType = contentType.change(parameters: {'charset': encoding.name});
 
     return new MultipartFile.fromBytes(field, encoding.encode(value),

From 55b1666144febf8aa5a78cdfc08c007e6bb4cce4 Mon Sep 17 00:00:00 2001
From: Don <don.j.olmstead@gmail.com>
Date: Tue, 24 Oct 2017 16:48:39 -0700
Subject: [PATCH 10/20] Add and pass tests

---
 lib/src/multipart_body.dart |   2 +-
 lib/src/request.dart        |   1 +
 test/multipart_test.dart    | 249 ++++++++++++++++++++++++++++++++++++
 test/utils.dart             |  39 +++++-
 4 files changed, 288 insertions(+), 3 deletions(-)
 create mode 100644 test/multipart_test.dart

diff --git a/lib/src/multipart_body.dart b/lib/src/multipart_body.dart
index 16f7ffd94c..3697bb0bf0 100644
--- a/lib/src/multipart_body.dart
+++ b/lib/src/multipart_body.dart
@@ -27,7 +27,7 @@ class MultipartBody implements Body {
   ///
   /// The [boundary] is used to
   factory MultipartBody(Map<String, String> fields,
-      Iterable<MultipartFile> files, String boundary) {
+      List<MultipartFile> files, String boundary) {
     var controller = new StreamController<List<int>>(sync: true);
     var contentLength = 0;
 
diff --git a/lib/src/request.dart b/lib/src/request.dart
index 17dee0bea4..9bcc6b6d5d 100644
--- a/lib/src/request.dart
+++ b/lib/src/request.dart
@@ -140,6 +140,7 @@ class Request extends Message {
         Iterable<MultipartFile> files}) {
     fields ??= <String, String>{};
     files ??= <MultipartFile>[];
+    headers ??= <String, String>{};
 
     var boundary = _boundaryString();
 
diff --git a/test/multipart_test.dart b/test/multipart_test.dart
new file mode 100644
index 0000000000..ba782396df
--- /dev/null
+++ b/test/multipart_test.dart
@@ -0,0 +1,249 @@
+// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'dart:async';
+
+import 'package:http/http.dart' as http;
+import 'package:http_parser/http_parser.dart';
+import 'package:test/test.dart';
+
+import 'utils.dart';
+
+void main() {
+  test('empty', () {
+    var request = new http.Request.multipart(dummyUrl);
+    expect(request, bodyMatches('''
+        --{{boundary}}--
+        '''));
+  });
+
+  test('with fields and files', () {
+    var fields = <String, String>{
+      'field1': 'value1',
+      'field2': 'value2',
+    };
+    var files = [
+      new http.MultipartFile.fromString("file1", "contents1",
+          filename: "filename1.txt"),
+      new http.MultipartFile.fromString("file2", "contents2"),
+    ];
+
+    var request =
+        new http.Request.multipart(dummyUrl, fields: fields, files: files);
+
+    expect(request, bodyMatches('''
+        --{{boundary}}
+        content-disposition: form-data; name="field1"
+
+        value1
+        --{{boundary}}
+        content-disposition: form-data; name="field2"
+
+        value2
+        --{{boundary}}
+        content-type: text/plain; charset=utf-8
+        content-disposition: form-data; name="file1"; filename="filename1.txt"
+
+        contents1
+        --{{boundary}}
+        content-type: text/plain; charset=utf-8
+        content-disposition: form-data; name="file2"
+
+        contents2
+        --{{boundary}}--
+        '''));
+  });
+
+  test('with a unicode field name', () {
+    var fields = {'fïēld': 'value'};
+
+    var request = new http.Request.multipart(dummyUrl, fields: fields);
+
+    expect(request, bodyMatches('''
+        --{{boundary}}
+        content-disposition: form-data; name="fïēld"
+
+        value
+        --{{boundary}}--
+        '''));
+  });
+
+  test('with a field name with newlines', () {
+    var fields = {'foo\nbar\rbaz\r\nbang': 'value'};
+    var request = new http.Request.multipart(dummyUrl, fields: fields);
+
+    expect(request, bodyMatches('''
+        --{{boundary}}
+        content-disposition: form-data; name="foo%0D%0Abar%0D%0Abaz%0D%0Abang"
+
+        value
+        --{{boundary}}--
+        '''));
+  });
+
+  test('with a field name with a quote', () {
+    var fields = {'foo"bar': 'value'};
+    var request = new http.Request.multipart(dummyUrl, fields: fields);
+
+    expect(request, bodyMatches('''
+        --{{boundary}}
+        content-disposition: form-data; name="foo%22bar"
+
+        value
+        --{{boundary}}--
+        '''));
+  });
+
+  test('with a unicode field value', () {
+    var fields = {'field': 'vⱥlūe'};
+    var request = new http.Request.multipart(dummyUrl, fields: fields);
+
+    expect(request, bodyMatches('''
+        --{{boundary}}
+        content-disposition: form-data; name="field"
+        content-type: text/plain; charset=utf-8
+        content-transfer-encoding: binary
+
+        vⱥlūe
+        --{{boundary}}--
+        '''));
+  });
+
+  test('with a unicode filename', () {
+    var files = [
+      new http.MultipartFile.fromString('file', 'contents',
+          filename: 'fïlēname.txt')
+    ];
+    var request = new http.Request.multipart(dummyUrl, files: files);
+
+    expect(request, bodyMatches('''
+        --{{boundary}}
+        content-type: text/plain; charset=utf-8
+        content-disposition: form-data; name="file"; filename="fïlēname.txt"
+
+        contents
+        --{{boundary}}--
+        '''));
+  });
+
+  test('with a filename with newlines', () {
+    var files = [
+      new http.MultipartFile.fromString('file', 'contents',
+          filename: 'foo\nbar\rbaz\r\nbang')
+    ];
+    var request = new http.Request.multipart(dummyUrl, files: files);
+
+    expect(request, bodyMatches('''
+        --{{boundary}}
+        content-type: text/plain; charset=utf-8
+        content-disposition: form-data; name="file"; filename="foo%0D%0Abar%0D%0Abaz%0D%0Abang"
+
+        contents
+        --{{boundary}}--
+        '''));
+  });
+
+  test('with a filename with a quote', () {
+    var files = [
+      new http.MultipartFile.fromString('file', 'contents', filename: 'foo"bar')
+    ];
+    var request = new http.Request.multipart(dummyUrl, files: files);
+
+    expect(request, bodyMatches('''
+        --{{boundary}}
+        content-type: text/plain; charset=utf-8
+        content-disposition: form-data; name="file"; filename="foo%22bar"
+
+        contents
+        --{{boundary}}--
+        '''));
+  });
+
+  test('with a string file with a content-type but no charset', () {
+    var files = [
+      new http.MultipartFile.fromString('file', '{"hello": "world"}',
+          contentType: new MediaType('application', 'json'))
+    ];
+    var request = new http.Request.multipart(dummyUrl, files: files);
+
+    expect(request, bodyMatches('''
+        --{{boundary}}
+        content-type: application/json; charset=utf-8
+        content-disposition: form-data; name="file"
+
+        {"hello": "world"}
+        --{{boundary}}--
+        '''));
+  });
+
+  test('with a file with a iso-8859-1 body', () {
+    // "Ã¥" encoded as ISO-8859-1 and then read as UTF-8 results in "å".
+    var files = [
+      new http.MultipartFile.fromString('file', 'non-ascii: "Ã¥"',
+          contentType:
+              new MediaType('text', 'plain', {'charset': 'iso-8859-1'}))
+    ];
+    var request = new http.Request.multipart(dummyUrl, files: files);
+
+    expect(request, bodyMatches('''
+        --{{boundary}}
+        content-type: text/plain; charset=iso-8859-1
+        content-disposition: form-data; name="file"
+
+        non-ascii: "å"
+        --{{boundary}}--
+        '''));
+  });
+
+  test('with a stream file', () {
+    var controller = new StreamController(sync: true);
+    var files = [new http.MultipartFile('file', controller.stream, 5)];
+    var request = new http.Request.multipart(dummyUrl, files: files);
+
+    expect(request, bodyMatches('''
+        --{{boundary}}
+        content-type: application/octet-stream
+        content-disposition: form-data; name="file"
+
+        hello
+        --{{boundary}}--
+        '''));
+
+    controller.add([104, 101, 108, 108, 111]);
+    controller.close();
+  });
+
+  test('with an empty stream file', () {
+    var controller = new StreamController(sync: true);
+    var files = [new http.MultipartFile('file', controller.stream, 0)];
+    var request = new http.Request.multipart(dummyUrl, files: files);
+
+    expect(request, bodyMatches('''
+        --{{boundary}}
+        content-type: application/octet-stream
+        content-disposition: form-data; name="file"
+
+
+        --{{boundary}}--
+        '''));
+
+    controller.close();
+  });
+
+  test('with a byte file', () {
+    var files = [
+      new http.MultipartFile.fromBytes('file', [104, 101, 108, 108, 111])
+    ];
+    var request = new http.Request.multipart(dummyUrl, files: files);
+
+    expect(request, bodyMatches('''
+        --{{boundary}}
+        content-type: application/octet-stream
+        content-disposition: form-data; name="file"
+
+        hello
+        --{{boundary}}--
+        '''));
+  });
+}
diff --git a/test/utils.dart b/test/utils.dart
index 505ee5fda3..a8858ad29c 100644
--- a/test/utils.dart
+++ b/test/utils.dart
@@ -4,9 +4,10 @@
 
 import 'dart:convert';
 
-import 'package:test/test.dart';
-
+import 'package:async/async.dart';
 import 'package:http/http.dart' as http;
+import 'package:http_parser/http_parser.dart';
+import 'package:test/test.dart';
 
 /// A dummy URL for constructing requests that won't be sent.
 Uri get dummyUrl => Uri.parse('http://dartlang.org/');
@@ -66,6 +67,40 @@ class _Parse extends Matcher {
   }
 }
 
+/// A matcher that validates the body of a multipart request after finalization.
+/// The string "{{boundary}}" in [pattern] will be replaced by the boundary
+/// string for the request, and LF newlines will be replaced with CRLF.
+/// Indentation will be normalized.
+Matcher bodyMatches(String pattern) => new _BodyMatches(pattern);
+
+class _BodyMatches extends Matcher {
+  final String _pattern;
+
+  _BodyMatches(this._pattern);
+
+  bool matches(item, Map matchState) {
+    if (item is! http.Request) return false;
+
+    var future = collectBytes(item.read()).then((bodyBytes) {
+      var body = UTF8.decode(bodyBytes);
+      var contentType = new MediaType.parse(item.headers['content-type']);
+      var boundary = contentType.parameters['boundary'];
+      var expected = cleanUpLiteral(_pattern)
+          .replaceAll("\n", "\r\n")
+          .replaceAll("{{boundary}}", boundary);
+
+      expect(body, equals(expected));
+      expect(item.contentLength, equals(bodyBytes.length));
+    });
+
+    return completes.matches(future, matchState);
+  }
+
+  Description describe(Description description) {
+    return description.add('has a body that matches "$_pattern"');
+  }
+}
+
 /// A matcher that matches a [http.ClientException] with the given [message].
 ///
 /// [message] can be a String or a [Matcher].

From 4866d51166e4d3a23aa1ea91ce5ae26733cea37f Mon Sep 17 00:00:00 2001
From: Don <don.j.olmstead@gmail.com>
Date: Tue, 24 Oct 2017 17:42:49 -0700
Subject: [PATCH 11/20] dartfmt

---
 lib/src/multipart_body.dart | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/src/multipart_body.dart b/lib/src/multipart_body.dart
index 3697bb0bf0..13045b917b 100644
--- a/lib/src/multipart_body.dart
+++ b/lib/src/multipart_body.dart
@@ -26,8 +26,8 @@ class MultipartBody implements Body {
   /// Creates a [MultipartBody] from the given [fields] and [files].
   ///
   /// The [boundary] is used to
-  factory MultipartBody(Map<String, String> fields,
-      List<MultipartFile> files, String boundary) {
+  factory MultipartBody(
+      Map<String, String> fields, List<MultipartFile> files, String boundary) {
     var controller = new StreamController<List<int>>(sync: true);
     var contentLength = 0;
 

From 7db4f18042657ad387ac5a4fc3aaefcc72c03398 Mon Sep 17 00:00:00 2001
From: Don <don.j.olmstead@gmail.com>
Date: Tue, 24 Oct 2017 17:54:28 -0700
Subject: [PATCH 12/20] Use Uint8Buffer

---
 lib/src/multipart_body.dart | 33 ++++++++++++++++++---------------
 pubspec.yaml                |  1 +
 2 files changed, 19 insertions(+), 15 deletions(-)

diff --git a/lib/src/multipart_body.dart b/lib/src/multipart_body.dart
index 13045b917b..efb1f75a01 100644
--- a/lib/src/multipart_body.dart
+++ b/lib/src/multipart_body.dart
@@ -5,6 +5,8 @@
 import 'dart:async';
 import 'dart:convert';
 
+import 'package:typed_data/typed_buffers.dart';
+
 import 'body.dart';
 import 'multipart_file.dart';
 import 'utils.dart';
@@ -26,25 +28,21 @@ class MultipartBody implements Body {
   /// Creates a [MultipartBody] from the given [fields] and [files].
   ///
   /// The [boundary] is used to
-  factory MultipartBody(
-      Map<String, String> fields, List<MultipartFile> files, String boundary) {
+  factory MultipartBody(Map<String, String> fields,
+      Iterable<MultipartFile> files, String boundary) {
     var controller = new StreamController<List<int>>(sync: true);
-    var contentLength = 0;
+    var buffer = new Uint8Buffer();
 
     void writeAscii(String string) {
-      controller.add(string.codeUnits);
-      contentLength += string.length;
+      buffer.addAll(string.codeUnits);
     }
 
     void writeUtf8(String string) {
-      var encoded = UTF8.encode(string);
-      controller.add(encoded);
-      contentLength += encoded.length;
+      buffer.addAll(UTF8.encode(string));
     }
 
     void writeLine() {
-      controller.add([13, 10]); // \r\n
-      contentLength += 2;
+      buffer.addAll([13, 10]); // \r\n
     }
 
     // Write the fields to the stream.
@@ -55,23 +53,27 @@ class MultipartBody implements Body {
       writeLine();
     });
 
+    controller.add(buffer);
+
     // Iterate over the files to get the length and compute the headers ahead
     // time so the length can be synchronously accessed.
+    var fileList = files.toList();
     var fileCount = files.length;
     var fileHeaders = new List<List<int>>(fileCount);
+    var fileContentsLength = 0;
 
     for (var i = 0; i < fileCount; ++i) {
-      var file = files[i];
+      var file = fileList[i];
       var header = <int>[];
       header.addAll('--$boundary\r\n'.codeUnits);
       header.addAll(UTF8.encode(_headerForFile(file)));
-      contentLength += header.length + file.length + 2;
+      fileContentsLength += header.length + file.length + 2;
       fileHeaders[i] = header;
     }
 
     // Ending characters.
     var ending = '--$boundary--\r\n'.codeUnits;
-    contentLength += ending.length;
+    fileContentsLength += ending.length;
 
     // Write the files to the stream.
     //
@@ -80,7 +82,7 @@ class MultipartBody implements Body {
     var i = 0;
 
     Future.forEach(files, (file) {
-      assert(files[i] == file);
+      assert(fileList[i] == file);
       controller.add(fileHeaders[i++]);
       return writeStreamToSink(file.read(), controller)
           .then((_) => controller.add([13, 10]));
@@ -91,7 +93,8 @@ class MultipartBody implements Body {
       controller.close();
     });
 
-    return new MultipartBody._(controller.stream, contentLength);
+    return new MultipartBody._(
+        controller.stream, buffer.length + fileContentsLength);
   }
 
   MultipartBody._(this._stream, this.contentLength);
diff --git a/pubspec.yaml b/pubspec.yaml
index 958b2babf8..503f083bf5 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -8,6 +8,7 @@ dependencies:
   collection: "^1.5.0"
   http_parser: ">=0.0.1 <4.0.0"
   path: ">=0.9.0 <2.0.0"
+  typed_data: "^1.1.5"
 dev_dependencies:
   test: "^0.12.18"
 # Override dependency on package_resolver to enable test

From 9609d5600a11ebda40badd8af2a42adc86a6ba90 Mon Sep 17 00:00:00 2001
From: Don <don.j.olmstead@gmail.com>
Date: Tue, 24 Oct 2017 18:06:11 -0700
Subject: [PATCH 13/20] Use async function for writing files

---
 lib/src/multipart_body.dart | 46 +++++++++++++++++++------------------
 1 file changed, 24 insertions(+), 22 deletions(-)

diff --git a/lib/src/multipart_body.dart b/lib/src/multipart_body.dart
index efb1f75a01..db1921f90b 100644
--- a/lib/src/multipart_body.dart
+++ b/lib/src/multipart_body.dart
@@ -11,6 +11,9 @@ import 'body.dart';
 import 'multipart_file.dart';
 import 'utils.dart';
 
+/// A `multipart/form-data` request [Body]. Such a request has both string
+/// fields, which function as normal form fields, and (potentially streamed)
+/// binary files.
 class MultipartBody implements Body {
   /// The contents of the message body.
   ///
@@ -58,40 +61,23 @@ class MultipartBody implements Body {
     // Iterate over the files to get the length and compute the headers ahead
     // time so the length can be synchronously accessed.
     var fileList = files.toList();
-    var fileCount = files.length;
-    var fileHeaders = new List<List<int>>(fileCount);
+    var fileHeaders = <List<int>>[];
     var fileContentsLength = 0;
 
-    for (var i = 0; i < fileCount; ++i) {
-      var file = fileList[i];
+    for (var file in fileList) {
       var header = <int>[];
       header.addAll('--$boundary\r\n'.codeUnits);
       header.addAll(UTF8.encode(_headerForFile(file)));
       fileContentsLength += header.length + file.length + 2;
-      fileHeaders[i] = header;
+      fileHeaders.add(header);
     }
 
     // Ending characters.
     var ending = '--$boundary--\r\n'.codeUnits;
     fileContentsLength += ending.length;
 
-    // Write the files to the stream.
-    //
-    // Future.forEach will ensure that the actions happen in sequence so i is
-    // used to get the fileHeaders.
-    var i = 0;
-
-    Future.forEach(files, (file) {
-      assert(fileList[i] == file);
-      controller.add(fileHeaders[i++]);
-      return writeStreamToSink(file.read(), controller)
-          .then((_) => controller.add([13, 10]));
-    }).then((_) {
-      // TODO(nweiz): pass any errors propagated through this future on to
-      // the stream. See issue 3657.
-      controller.add(ending);
-      controller.close();
-    });
+    // Write the files to the stream asynchronously.
+    _writeFilesToStream(controller, files, fileHeaders, ending);
 
     return new MultipartBody._(
         controller.stream, buffer.length + fileContentsLength);
@@ -112,6 +98,22 @@ class MultipartBody implements Body {
     return stream;
   }
 
+  /// Writes the [files] to the [controller].
+  static Future _writeFilesToStream(
+      StreamController<List<int>> controller,
+      List<MultipartFile> files,
+      List<List<int>> fileHeaders,
+      List<int> ending) async {
+    for (var i = 0; i < files.length; ++i) {
+      controller.add(fileHeaders[i]);
+      await writeStreamToSink(files[i].read(), controller);
+      controller.add([13, 10]);
+    }
+
+    controller.add(ending);
+    controller.close();
+  }
+
   /// Returns the header string for a field.
   static String _headerForField(String name, String value) {
     var header =

From 39667b7fa2e6fbb7b3ddf10d17c3f9866a6ed365 Mon Sep 17 00:00:00 2001
From: Don <don.j.olmstead@gmail.com>
Date: Wed, 25 Oct 2017 11:42:38 -0700
Subject: [PATCH 14/20] Fixing review comments

---
 lib/src/boundary.dart       |  41 ++++++++++++++
 lib/src/multipart_body.dart |  52 +++++++++---------
 lib/src/multipart_file.dart |   5 +-
 lib/src/request.dart        | 104 ++++++++++++------------------------
 pubspec.yaml                |   2 +-
 test/multipart_test.dart    |  45 ++++++++--------
 test/utils.dart             |  34 ++++++------
 7 files changed, 148 insertions(+), 135 deletions(-)
 create mode 100644 lib/src/boundary.dart

diff --git a/lib/src/boundary.dart b/lib/src/boundary.dart
new file mode 100644
index 0000000000..6dd352daad
--- /dev/null
+++ b/lib/src/boundary.dart
@@ -0,0 +1,41 @@
+// Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'dart:math';
+
+/// All character codes that are valid in multipart boundaries.
+///
+/// This is the intersection of the characters allowed in the `bcharsnospace`
+/// production defined in [RFC 2046][] and those allowed in the `token`
+/// production defined in [RFC 1521][].
+///
+/// [RFC 2046]: http://tools.ietf.org/html/rfc2046#section-5.1.1.
+/// [RFC 1521]: https://tools.ietf.org/html/rfc1521#section-4
+const List<int> _boundaryCharacters = const <int>[
+  43, 95, 45, 46, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 65, 66, 67, 68, //
+  69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86,
+  87, 88, 89, 90, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107,
+  108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121,
+  122
+];
+
+/// The total length of the multipart boundaries used when building the
+/// request body.
+///
+/// According to http://tools.ietf.org/html/rfc1341.html, this can't be longer
+/// than 70.
+const int _boundaryLength = 70;
+
+final Random _random = new Random();
+
+/// Returns a randomly-generated multipart boundary string
+String boundaryString() {
+  var prefix = 'dart-http-boundary-';
+  var list = new List<int>.generate(
+      _boundaryLength - prefix.length,
+      (index) =>
+          _boundaryCharacters[_random.nextInt(_boundaryCharacters.length)],
+      growable: false);
+  return '$prefix${new String.fromCharCodes(list)}';
+}
diff --git a/lib/src/multipart_body.dart b/lib/src/multipart_body.dart
index db1921f90b..f546e78b2b 100644
--- a/lib/src/multipart_body.dart
+++ b/lib/src/multipart_body.dart
@@ -1,4 +1,4 @@
-// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
+// Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
@@ -20,9 +20,6 @@ class MultipartBody implements Body {
   /// This will be `null` after [read] is called.
   Stream<List<int>> _stream;
 
-  /// The length of the stream returned by [read].
-  ///
-  /// This is calculated from the fields and files passed into the body.
   final int contentLength;
 
   /// Multipart forms do not have an encoding.
@@ -30,7 +27,7 @@ class MultipartBody implements Body {
 
   /// Creates a [MultipartBody] from the given [fields] and [files].
   ///
-  /// The [boundary] is used to
+  /// The [boundary] is used to separate key value pairs within the body.
   factory MultipartBody(Map<String, String> fields,
       Iterable<MultipartFile> files, String boundary) {
     var controller = new StreamController<List<int>>(sync: true);
@@ -45,10 +42,10 @@ class MultipartBody implements Body {
     }
 
     void writeLine() {
-      buffer.addAll([13, 10]); // \r\n
+      buffer..add(13)..add(10); // \r\n
     }
 
-    // Write the fields to the stream.
+    // Write the fields to the buffer.
     fields.forEach((name, value) {
       writeAscii('--$boundary\r\n');
       writeUtf8(_headerForField(name, value));
@@ -58,16 +55,17 @@ class MultipartBody implements Body {
 
     controller.add(buffer);
 
-    // Iterate over the files to get the length and compute the headers ahead
+    // Iterate over the files to get the length and compute the headers ahead of
     // time so the length can be synchronously accessed.
     var fileList = files.toList();
     var fileHeaders = <List<int>>[];
     var fileContentsLength = 0;
 
     for (var file in fileList) {
-      var header = <int>[];
-      header.addAll('--$boundary\r\n'.codeUnits);
-      header.addAll(UTF8.encode(_headerForFile(file)));
+      var header = <int>[]
+        ..addAll('--$boundary\r\n'.codeUnits)
+        ..addAll(UTF8.encode(_headerForFile(file)));
+
       fileContentsLength += header.length + file.length + 2;
       fileHeaders.add(header);
     }
@@ -77,7 +75,7 @@ class MultipartBody implements Body {
     fileContentsLength += ending.length;
 
     // Write the files to the stream asynchronously.
-    _writeFilesToStream(controller, files, fileHeaders, ending);
+    _writeFilesToStream(controller, fileList, fileHeaders, ending);
 
     return new MultipartBody._(
         controller.stream, buffer.length + fileContentsLength);
@@ -91,7 +89,7 @@ class MultipartBody implements Body {
   Stream<List<int>> read() {
     if (_stream == null) {
       throw new StateError("The 'read' method can only be called once on a "
-          "http.Request/http.Response object.");
+          'http.Request/http.Response object.');
     }
     var stream = _stream;
     _stream = null;
@@ -106,12 +104,17 @@ class MultipartBody implements Body {
       List<int> ending) async {
     for (var i = 0; i < files.length; ++i) {
       controller.add(fileHeaders[i]);
-      await writeStreamToSink(files[i].read(), controller);
+      try {
+        await writeStreamToSink(files[i].read(), controller);
+      } on Exception catch (exception, stackTrace) {
+        controller.addError(exception, stackTrace);
+      }
       controller.add([13, 10]);
     }
 
-    controller.add(ending);
-    controller.close();
+    controller
+      ..add(ending)
+      ..close();
   }
 
   /// Returns the header string for a field.
@@ -139,15 +142,14 @@ class MultipartBody implements Body {
     return '$header\r\n\r\n';
   }
 
-  static final _newlineRegExp = new RegExp(r"\r\n|\r|\n");
+  static final _newlineRegExp = new RegExp(r'\r\n|\r|\n');
 
   /// Encode [value] in the same way browsers do.
-  static String _browserEncode(String value) {
-    // http://tools.ietf.org/html/rfc2388 mandates some complex encodings for
-    // field names and file names, but in practice user agents seem not to
-    // follow this at all. Instead, they URL-encode `\r`, `\n`, and `\r\n` as
-    // `\r\n`; URL-encode `"`; and do nothing else (even for `%` or non-ASCII
-    // characters). We follow their behavior.
-    return value.replaceAll(_newlineRegExp, "%0D%0A").replaceAll('"', "%22");
-  }
+  static String _browserEncode(String value) =>
+      // http://tools.ietf.org/html/rfc2388 mandates some complex encodings for
+      // field names and file names, but in practice user agents seem not to
+      // follow this at all. Instead, they URL-encode `\r`, `\n`, and `\r\n` as
+      // `\r\n`; URL-encode `"`; and do nothing else (even for `%` or non-ASCII
+      // characters). We follow their behavior.
+      value.replaceAll(_newlineRegExp, '%0D%0A').replaceAll('"', '%22');
 }
diff --git a/lib/src/multipart_file.dart b/lib/src/multipart_file.dart
index d3cc44398a..9aef80e1eb 100644
--- a/lib/src/multipart_file.dart
+++ b/lib/src/multipart_file.dart
@@ -13,8 +13,9 @@ import 'package:path/path.dart' as path;
 
 import 'content_type.dart';
 
-/// A file to be uploaded as part of a [MultipartRequest]. This doesn't need to
-/// correspond to a physical file.
+/// A file to be uploaded as part of a `multipart/form-data` Request.
+///
+/// This doesn't need to correspond to a physical file.
 class MultipartFile {
   /// The stream that will emit the file's contents.
   Stream<List<int>> _stream;
diff --git a/lib/src/request.dart b/lib/src/request.dart
index 9bcc6b6d5d..20c1c2727e 100644
--- a/lib/src/request.dart
+++ b/lib/src/request.dart
@@ -3,11 +3,11 @@
 // BSD-style license that can be found in the LICENSE file.
 
 import 'dart:convert';
-import 'dart:math';
 
+import 'boundary.dart';
 import 'message.dart';
-import 'multipart_file.dart';
 import 'multipart_body.dart';
+import 'multipart_file.dart';
 import 'utils.dart';
 
 /// Represents an HTTP request to be sent to a server.
@@ -48,8 +48,7 @@ class Request extends Message {
   ///
   /// Extra [context] can be used to pass information between inner middleware
   /// and handlers.
-  Request.head(url,
-      {Map<String, String> headers, Map<String, Object> context})
+  Request.head(url, {Map<String, String> headers, Map<String, Object> context})
       : this('HEAD', url, headers: headers, context: context);
 
   /// Creates a new GET [Request] to [url], which can be a [Uri] or a [String].
@@ -59,8 +58,7 @@ class Request extends Message {
   ///
   /// Extra [context] can be used to pass information between inner middleware
   /// and handlers.
-  Request.get(url,
-      {Map<String, String> headers, Map<String, Object> context})
+  Request.get(url, {Map<String, String> headers, Map<String, Object> context})
       : this('GET', url, headers: headers, context: context);
 
   /// Creates a new POST [Request] to [url], which can be a [Uri] or a [String].
@@ -80,7 +78,7 @@ class Request extends Message {
       Map<String, String> headers,
       Map<String, Object> context})
       : this('POST', url,
-      body: body, encoding: encoding, headers: headers, context: context);
+            body: body, encoding: encoding, headers: headers, context: context);
 
   /// Creates a new PUT [Request] to [url], which can be a [Uri] or a [String].
   ///
@@ -99,7 +97,7 @@ class Request extends Message {
       Map<String, String> headers,
       Map<String, Object> context})
       : this('PUT', url,
-      body: body, encoding: encoding, headers: headers, context: context);
+            body: body, encoding: encoding, headers: headers, context: context);
 
   /// Creates a new PATCH [Request] to [url], which can be a [Uri] or a
   /// [String].
@@ -119,7 +117,7 @@ class Request extends Message {
       Map<String, String> headers,
       Map<String, Object> context})
       : this('PATCH', url,
-      body: body, encoding: encoding, headers: headers, context: context);
+            body: body, encoding: encoding, headers: headers, context: context);
 
   /// Creates a new DELETE [Request] to [url], which can be a [Uri] or a
   /// [String].
@@ -133,33 +131,43 @@ class Request extends Message {
       {Map<String, String> headers, Map<String, Object> context})
       : this('DELETE', url, headers: headers, context: context);
 
+  /// Creates a new `multipart/form-data` [Request] to [url], which can be a
+  /// [Uri] or a [String].
+  ///
+  /// The content of the body is specified through the values of [fields] and
+  /// [files].
+  ///
+  /// If [method] is not specified it defaults to POST.
+  ///
+  /// [headers] are the HTTP headers for the request. If [headers] is `null`,
+  /// it is treated as empty.
+  ///
+  /// Extra [context] can be used to pass information between inner middleware
+  /// and handlers.
   factory Request.multipart(url,
-      {Map<String, String> headers,
-        Map<String, Object> context,
-        Map<String, String> fields,
-        Iterable<MultipartFile> files}) {
+      {String method,
+      Map<String, String> headers,
+      Map<String, Object> context,
+      Map<String, String> fields,
+      Iterable<MultipartFile> files}) {
     fields ??= <String, String>{};
     files ??= <MultipartFile>[];
     headers ??= <String, String>{};
 
-    var boundary = _boundaryString();
+    var boundary = boundaryString();
 
     return new Request._(
-        'POST',
-        url,
+        method ?? 'POST',
+        getUrl(url),
         new MultipartBody(fields, files, boundary),
         null,
-        updateMap(headers, <String, String>{
-          'content-type': 'multipart/form-data; boundary=$boundary'
-        }),
+        updateMap(headers,
+            {'content-type': 'multipart/form-data; boundary=$boundary'}),
         context);
   }
 
-  Request._(this.method, this.url,
-      body,
-      Encoding encoding,
-      Map<String, String> headers,
-      Map<String, Object> context)
+  Request._(this.method, this.url, body, Encoding encoding,
+      Map<String, String> headers, Map<String, Object> context)
       : super(body, encoding: encoding, headers: headers, context: context);
 
   /// Creates a new [Request] by copying existing values and applying specified
@@ -174,53 +182,11 @@ class Request extends Message {
   /// [body] is the request body. It may be either a [String], a [List<int>], a
   /// [Stream<List<int>>], or `null` to indicate no body.
   Request change(
-      {Map<String, String> headers,
-      Map<String, Object> context,
-      body}) {
+      {Map<String, String> headers, Map<String, Object> context, body}) {
     var updatedHeaders = updateMap(this.headers, headers);
     var updatedContext = updateMap(this.context, context);
 
-    return new Request._(
-        this.method,
-        this.url,
-        body ?? getBody(this),
-        this.encoding,
-        updatedHeaders,
-        updatedContext);
-  }
-
-  /// All character codes that are valid in multipart boundaries.
-  ///
-  /// This is the intersection of the characters allowed in the `bcharsnospace`
-  /// production defined in [RFC 2046][] and those allowed in the `token`
-  /// production defined in [RFC 1521][].
-  ///
-  /// [RFC 2046]: http://tools.ietf.org/html/rfc2046#section-5.1.1.
-  /// [RFC 1521]: https://tools.ietf.org/html/rfc1521#section-4
-  static const List<int> _boundaryCharacters = const <int>[
-    43, 95, 45, 46, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 65, 66, 67, 68, //
-    69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, //
-    87, 88, 89, 90, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107,     //
-    108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121,   //
-    122
-  ];
-
-  /// The total length of the multipart boundaries used when building the
-  /// request body.
-  ///
-  /// According to http://tools.ietf.org/html/rfc1341.html, this can't be longer
-  /// than 70.
-  static const int _boundaryLength = 70;
-
-  static final Random _random = new Random();
-
-  /// Returns a randomly-generated multipart boundary string
-  static String _boundaryString() {
-    var prefix = "dart-http-boundary-";
-    var list = new List<int>.generate(_boundaryLength - prefix.length,
-            (index) =>
-        _boundaryCharacters[_random.nextInt(_boundaryCharacters.length)],
-        growable: false);
-    return "$prefix${new String.fromCharCodes(list)}";
+    return new Request._(this.method, this.url, body ?? getBody(this),
+        this.encoding, updatedHeaders, updatedContext);
   }
 }
diff --git a/pubspec.yaml b/pubspec.yaml
index 503f083bf5..fad3da5f58 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -8,7 +8,7 @@ dependencies:
   collection: "^1.5.0"
   http_parser: ">=0.0.1 <4.0.0"
   path: ">=0.9.0 <2.0.0"
-  typed_data: "^1.1.5"
+  typed_data: "^1.0.0"
 dev_dependencies:
   test: "^0.12.18"
 # Override dependency on package_resolver to enable test
diff --git a/test/multipart_test.dart b/test/multipart_test.dart
index ba782396df..f6b9afff3e 100644
--- a/test/multipart_test.dart
+++ b/test/multipart_test.dart
@@ -1,4 +1,4 @@
-// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
+// Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
@@ -13,7 +13,7 @@ import 'utils.dart';
 void main() {
   test('empty', () {
     var request = new http.Request.multipart(dummyUrl);
-    expect(request, bodyMatches('''
+    expect(request, multipartBodyMatches('''
         --{{boundary}}--
         '''));
   });
@@ -24,15 +24,15 @@ void main() {
       'field2': 'value2',
     };
     var files = [
-      new http.MultipartFile.fromString("file1", "contents1",
-          filename: "filename1.txt"),
-      new http.MultipartFile.fromString("file2", "contents2"),
+      new http.MultipartFile.fromString('file1', 'contents1',
+          filename: 'filename1.txt'),
+      new http.MultipartFile.fromString('file2', 'contents2'),
     ];
 
     var request =
         new http.Request.multipart(dummyUrl, fields: fields, files: files);
 
-    expect(request, bodyMatches('''
+    expect(request, multipartBodyMatches('''
         --{{boundary}}
         content-disposition: form-data; name="field1"
 
@@ -60,7 +60,7 @@ void main() {
 
     var request = new http.Request.multipart(dummyUrl, fields: fields);
 
-    expect(request, bodyMatches('''
+    expect(request, multipartBodyMatches('''
         --{{boundary}}
         content-disposition: form-data; name="fïēld"
 
@@ -73,7 +73,7 @@ void main() {
     var fields = {'foo\nbar\rbaz\r\nbang': 'value'};
     var request = new http.Request.multipart(dummyUrl, fields: fields);
 
-    expect(request, bodyMatches('''
+    expect(request, multipartBodyMatches('''
         --{{boundary}}
         content-disposition: form-data; name="foo%0D%0Abar%0D%0Abaz%0D%0Abang"
 
@@ -86,7 +86,7 @@ void main() {
     var fields = {'foo"bar': 'value'};
     var request = new http.Request.multipart(dummyUrl, fields: fields);
 
-    expect(request, bodyMatches('''
+    expect(request, multipartBodyMatches('''
         --{{boundary}}
         content-disposition: form-data; name="foo%22bar"
 
@@ -99,7 +99,7 @@ void main() {
     var fields = {'field': 'vⱥlūe'};
     var request = new http.Request.multipart(dummyUrl, fields: fields);
 
-    expect(request, bodyMatches('''
+    expect(request, multipartBodyMatches('''
         --{{boundary}}
         content-disposition: form-data; name="field"
         content-type: text/plain; charset=utf-8
@@ -117,7 +117,7 @@ void main() {
     ];
     var request = new http.Request.multipart(dummyUrl, files: files);
 
-    expect(request, bodyMatches('''
+    expect(request, multipartBodyMatches('''
         --{{boundary}}
         content-type: text/plain; charset=utf-8
         content-disposition: form-data; name="file"; filename="fïlēname.txt"
@@ -134,7 +134,7 @@ void main() {
     ];
     var request = new http.Request.multipart(dummyUrl, files: files);
 
-    expect(request, bodyMatches('''
+    expect(request, multipartBodyMatches('''
         --{{boundary}}
         content-type: text/plain; charset=utf-8
         content-disposition: form-data; name="file"; filename="foo%0D%0Abar%0D%0Abaz%0D%0Abang"
@@ -150,7 +150,7 @@ void main() {
     ];
     var request = new http.Request.multipart(dummyUrl, files: files);
 
-    expect(request, bodyMatches('''
+    expect(request, multipartBodyMatches('''
         --{{boundary}}
         content-type: text/plain; charset=utf-8
         content-disposition: form-data; name="file"; filename="foo%22bar"
@@ -167,7 +167,7 @@ void main() {
     ];
     var request = new http.Request.multipart(dummyUrl, files: files);
 
-    expect(request, bodyMatches('''
+    expect(request, multipartBodyMatches('''
         --{{boundary}}
         content-type: application/json; charset=utf-8
         content-disposition: form-data; name="file"
@@ -186,7 +186,7 @@ void main() {
     ];
     var request = new http.Request.multipart(dummyUrl, files: files);
 
-    expect(request, bodyMatches('''
+    expect(request, multipartBodyMatches('''
         --{{boundary}}
         content-type: text/plain; charset=iso-8859-1
         content-disposition: form-data; name="file"
@@ -197,11 +197,11 @@ void main() {
   });
 
   test('with a stream file', () {
-    var controller = new StreamController(sync: true);
+    var controller = new StreamController<List<int>>(sync: true);
     var files = [new http.MultipartFile('file', controller.stream, 5)];
     var request = new http.Request.multipart(dummyUrl, files: files);
 
-    expect(request, bodyMatches('''
+    expect(request, multipartBodyMatches('''
         --{{boundary}}
         content-type: application/octet-stream
         content-disposition: form-data; name="file"
@@ -210,16 +210,17 @@ void main() {
         --{{boundary}}--
         '''));
 
-    controller.add([104, 101, 108, 108, 111]);
-    controller.close();
+    controller
+      ..add([104, 101, 108, 108, 111])
+      ..close();
   });
 
   test('with an empty stream file', () {
-    var controller = new StreamController(sync: true);
+    var controller = new StreamController<List<int>>(sync: true);
     var files = [new http.MultipartFile('file', controller.stream, 0)];
     var request = new http.Request.multipart(dummyUrl, files: files);
 
-    expect(request, bodyMatches('''
+    expect(request, multipartBodyMatches('''
         --{{boundary}}
         content-type: application/octet-stream
         content-disposition: form-data; name="file"
@@ -237,7 +238,7 @@ void main() {
     ];
     var request = new http.Request.multipart(dummyUrl, files: files);
 
-    expect(request, bodyMatches('''
+    expect(request, multipartBodyMatches('''
         --{{boundary}}
         content-type: application/octet-stream
         content-disposition: form-data; name="file"
diff --git a/test/utils.dart b/test/utils.dart
index a8858ad29c..72e77791ec 100644
--- a/test/utils.dart
+++ b/test/utils.dart
@@ -62,21 +62,24 @@ class _Parse extends Matcher {
   }
 
   Description describe(Description description) {
-    return description.add('parses to a value that ')
-      .addDescriptionOf(_matcher);
+    return description
+        .add('parses to a value that ')
+        .addDescriptionOf(_matcher);
   }
 }
 
 /// A matcher that validates the body of a multipart request after finalization.
+///
 /// The string "{{boundary}}" in [pattern] will be replaced by the boundary
 /// string for the request, and LF newlines will be replaced with CRLF.
 /// Indentation will be normalized.
-Matcher bodyMatches(String pattern) => new _BodyMatches(pattern);
+Matcher multipartBodyMatches(String pattern) =>
+    new _MultipartBodyMatches(pattern);
 
-class _BodyMatches extends Matcher {
+class _MultipartBodyMatches extends Matcher {
   final String _pattern;
 
-  _BodyMatches(this._pattern);
+  _MultipartBodyMatches(this._pattern);
 
   bool matches(item, Map matchState) {
     if (item is! http.Request) return false;
@@ -86,8 +89,8 @@ class _BodyMatches extends Matcher {
       var contentType = new MediaType.parse(item.headers['content-type']);
       var boundary = contentType.parameters['boundary'];
       var expected = cleanUpLiteral(_pattern)
-          .replaceAll("\n", "\r\n")
-          .replaceAll("{{boundary}}", boundary);
+          .replaceAll('\n', '\r\n')
+          .replaceAll('{{boundary}}', boundary);
 
       expect(body, equals(expected));
       expect(item.contentLength, equals(bodyBytes.length));
@@ -96,21 +99,20 @@ class _BodyMatches extends Matcher {
     return completes.matches(future, matchState);
   }
 
-  Description describe(Description description) {
-    return description.add('has a body that matches "$_pattern"');
-  }
+  Description describe(Description description) =>
+      description.add('has a body that matches "$_pattern"');
 }
 
 /// A matcher that matches a [http.ClientException] with the given [message].
 ///
 /// [message] can be a String or a [Matcher].
 Matcher isClientException([message]) => predicate((error) {
-  expect(error, new isInstanceOf<http.ClientException>());
-  if (message != null) {
-    expect(error.message, message);
-  }
-  return true;
-});
+      expect(error, new isInstanceOf<http.ClientException>());
+      if (message != null) {
+        expect(error.message, message);
+      }
+      return true;
+    });
 
 /// A matcher that matches function or future that throws a
 /// [http.ClientException] with the given [message].

From 28208ae90e6fe99e431cc3cfe92f394b1a6a988f Mon Sep 17 00:00:00 2001
From: Don <don.j.olmstead@gmail.com>
Date: Wed, 25 Oct 2017 12:01:53 -0700
Subject: [PATCH 15/20] nits

---
 lib/src/request.dart | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/lib/src/request.dart b/lib/src/request.dart
index 20c1c2727e..5e45428d6e 100644
--- a/lib/src/request.dart
+++ b/lib/src/request.dart
@@ -150,9 +150,9 @@ class Request extends Message {
       Map<String, Object> context,
       Map<String, String> fields,
       Iterable<MultipartFile> files}) {
-    fields ??= <String, String>{};
-    files ??= <MultipartFile>[];
-    headers ??= <String, String>{};
+    fields ??= const {};
+    files ??= const [];
+    headers ??= {};
 
     var boundary = boundaryString();
 

From 83bfc8d36b1540e93575b0b75cde0c93c0e89550 Mon Sep 17 00:00:00 2001
From: Don <don.j.olmstead@gmail.com>
Date: Wed, 25 Oct 2017 16:14:59 -0700
Subject: [PATCH 16/20] Update with modified constructors

---
 lib/src/multipart_file.dart | 106 ++++++++++++++++++------------------
 pubspec.yaml                |   2 +-
 test/multipart_test.dart    |  26 +++++----
 3 files changed, 68 insertions(+), 66 deletions(-)

diff --git a/lib/src/multipart_file.dart b/lib/src/multipart_file.dart
index 9aef80e1eb..c53ad7c265 100644
--- a/lib/src/multipart_file.dart
+++ b/lib/src/multipart_file.dart
@@ -4,12 +4,10 @@
 
 import 'dart:async';
 import 'dart:convert';
-import 'dart:io';
 
 import 'package:async/async.dart';
-import 'package:collection/collection.dart';
 import 'package:http_parser/http_parser.dart';
-import 'package:path/path.dart' as path;
+import 'package:mime/mime.dart';
 
 import 'content_type.dart';
 
@@ -37,62 +35,52 @@ class MultipartFile {
   /// Defaults to `application/octet-stream`.
   final MediaType contentType;
 
-  /// Creates a new [MultipartFile] from a chunked [Stream] of bytes.
   ///
-  /// The length of the file in bytes must be known in advance. If it's not,
-  /// read the data from the stream and use [MultipartFile.fromBytes] instead.
-  ///
-  /// [contentType] currently defaults to `application/octet-stream`, but in the
-  /// future may be inferred from [filename].
-  MultipartFile(this.field, Stream<List<int>> stream, this.length,
-      {this.filename, MediaType contentType})
-      : this._stream = stream,
-        this.contentType =
-            contentType ?? new MediaType("application", "octet-stream");
-
-  /// Creates a new [MultipartFile] from a byte array.
-  ///
-  /// [contentType] currently defaults to `application/octet-stream`, but in the
-  /// future may be inferred from [filename].
-  factory MultipartFile.fromBytes(String field, List<int> value,
-      {String filename, MediaType contentType}) {
-    var stream = new Stream.fromIterable([DelegatingList.typed(value)]);
-    return new MultipartFile(field, stream, value.length,
-        filename: filename, contentType: contentType);
-  }
+  factory MultipartFile(String field, value,
+      {String filename, MediaType contentType, Encoding encoding}) {
+    List<int> bytes;
+    var defaultMediaType;
 
-  /// Creates a new [MultipartFile] from a string.
-  ///
-  /// The encoding to use when translating [value] into bytes is taken from
-  /// [contentType] if it has a charset set. Otherwise, it defaults to UTF-8.
-  /// [contentType] currently defaults to `text/plain; charset=utf-8`, but in
-  /// the future may be inferred from [filename].
-  factory MultipartFile.fromString(String field, String value,
-      {String filename, MediaType contentType}) {
-    contentType ??= new MediaType("text", "plain");
-    var encoding = encodingForMediaType(contentType) ?? UTF8;
-    contentType = contentType.change(parameters: {'charset': encoding.name});
-
-    return new MultipartFile.fromBytes(field, encoding.encode(value),
+    if (value is String) {
+      encoding ??= encodingForMediaType(contentType) ?? UTF8;
+      bytes = encoding.encode(value);
+      defaultMediaType = new MediaType('text', 'plain');
+    } else if (value is List<int>) {
+      bytes = value;
+      defaultMediaType = new MediaType('application', 'octet-stream');
+    } else {
+      throw new ArgumentError.value(
+          value,
+          'value',
+          'value must be either a '
+          'String or a List<int>');
+    }
+
+    contentType ??= _lookupMediaType(filename, bytes) ?? defaultMediaType;
+
+    if (encoding != null) {
+      contentType = contentType.change(parameters: {'charset': encoding.name});
+    }
+
+    return new MultipartFile.fromStream(
+        field, new Stream<List<int>>.fromIterable([bytes]), bytes.length,
         filename: filename, contentType: contentType);
   }
 
-  // TODO(nweiz): Infer the content-type from the filename.
-  /// Creates a new [MultipartFile] from a path to a file on disk.
-  ///
-  /// [filename] defaults to the basename of [filePath]. [contentType] currently
-  /// defaults to `application/octet-stream`, but in the future may be inferred
-  /// from [filename].
-  ///
-  /// Throws an [UnsupportedError] if `dart:io` isn't supported in this
-  /// environment.
-  static Future<MultipartFile> fromPath(String field, String filePath,
+  MultipartFile.fromStream(this.field, Stream<List<int>> stream, this.length,
+      {String filename, MediaType contentType})
+      : _stream = stream,
+        filename = filename,
+        contentType = contentType ??
+            _lookupMediaType(filename) ??
+            new MediaType('application', 'octet-stream');
+
+  static Future<MultipartFile> loadStream(
+      String field, Stream<List<int>> stream,
       {String filename, MediaType contentType}) async {
-    if (filename == null) filename = path.basename(filePath);
-    var file = new File(filePath);
-    var length = await file.length();
-    var stream = DelegatingStream.typed(file.openRead());
-    return new MultipartFile(field, stream, length,
+    var bytes = await collectBytes(stream);
+
+    return new MultipartFile(field, bytes,
         filename: filename, contentType: contentType);
   }
 
@@ -108,4 +96,16 @@ class MultipartFile {
     _stream = null;
     return stream;
   }
+
+  /// Looks up the [MediaType] from the [filename]'s extension or from
+  /// magic numbers contained within a file header's [bytes].
+  static MediaType _lookupMediaType(String filename, [List<int> bytes]) {
+    if ((filename == null) && (bytes == null)) return null;
+
+    // lookupMimeType expects filename to be non-null but its possible that
+    // this can be called with bytes but no filename.
+    var mimeType = lookupMimeType(filename ?? '', headerBytes: bytes);
+
+    return mimeType != null ? new MediaType.parse(mimeType) : null;
+  }
 }
diff --git a/pubspec.yaml b/pubspec.yaml
index fad3da5f58..1c3ebefa2f 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -7,7 +7,7 @@ dependencies:
   async: "^1.13.0"
   collection: "^1.5.0"
   http_parser: ">=0.0.1 <4.0.0"
-  path: ">=0.9.0 <2.0.0"
+  mime: ">=0.9.0 < 1.0.0"
   typed_data: "^1.0.0"
 dev_dependencies:
   test: "^0.12.18"
diff --git a/test/multipart_test.dart b/test/multipart_test.dart
index f6b9afff3e..d3302d0930 100644
--- a/test/multipart_test.dart
+++ b/test/multipart_test.dart
@@ -24,9 +24,8 @@ void main() {
       'field2': 'value2',
     };
     var files = [
-      new http.MultipartFile.fromString('file1', 'contents1',
-          filename: 'filename1.txt'),
-      new http.MultipartFile.fromString('file2', 'contents2'),
+      new http.MultipartFile('file1', 'contents1', filename: 'filename1.txt'),
+      new http.MultipartFile('file2', 'contents2'),
     ];
 
     var request =
@@ -112,8 +111,7 @@ void main() {
 
   test('with a unicode filename', () {
     var files = [
-      new http.MultipartFile.fromString('file', 'contents',
-          filename: 'fïlēname.txt')
+      new http.MultipartFile('file', 'contents', filename: 'fïlēname.txt')
     ];
     var request = new http.Request.multipart(dummyUrl, files: files);
 
@@ -129,7 +127,7 @@ void main() {
 
   test('with a filename with newlines', () {
     var files = [
-      new http.MultipartFile.fromString('file', 'contents',
+      new http.MultipartFile('file', 'contents',
           filename: 'foo\nbar\rbaz\r\nbang')
     ];
     var request = new http.Request.multipart(dummyUrl, files: files);
@@ -146,7 +144,7 @@ void main() {
 
   test('with a filename with a quote', () {
     var files = [
-      new http.MultipartFile.fromString('file', 'contents', filename: 'foo"bar')
+      new http.MultipartFile('file', 'contents', filename: 'foo"bar')
     ];
     var request = new http.Request.multipart(dummyUrl, files: files);
 
@@ -162,7 +160,7 @@ void main() {
 
   test('with a string file with a content-type but no charset', () {
     var files = [
-      new http.MultipartFile.fromString('file', '{"hello": "world"}',
+      new http.MultipartFile('file', '{"hello": "world"}',
           contentType: new MediaType('application', 'json'))
     ];
     var request = new http.Request.multipart(dummyUrl, files: files);
@@ -180,7 +178,7 @@ void main() {
   test('with a file with a iso-8859-1 body', () {
     // "Ã¥" encoded as ISO-8859-1 and then read as UTF-8 results in "å".
     var files = [
-      new http.MultipartFile.fromString('file', 'non-ascii: "Ã¥"',
+      new http.MultipartFile('file', 'non-ascii: "Ã¥"',
           contentType:
               new MediaType('text', 'plain', {'charset': 'iso-8859-1'}))
     ];
@@ -198,7 +196,9 @@ void main() {
 
   test('with a stream file', () {
     var controller = new StreamController<List<int>>(sync: true);
-    var files = [new http.MultipartFile('file', controller.stream, 5)];
+    var files = [
+      new http.MultipartFile.fromStream('file', controller.stream, 5)
+    ];
     var request = new http.Request.multipart(dummyUrl, files: files);
 
     expect(request, multipartBodyMatches('''
@@ -217,7 +217,9 @@ void main() {
 
   test('with an empty stream file', () {
     var controller = new StreamController<List<int>>(sync: true);
-    var files = [new http.MultipartFile('file', controller.stream, 0)];
+    var files = [
+      new http.MultipartFile.fromStream('file', controller.stream, 0)
+    ];
     var request = new http.Request.multipart(dummyUrl, files: files);
 
     expect(request, multipartBodyMatches('''
@@ -234,7 +236,7 @@ void main() {
 
   test('with a byte file', () {
     var files = [
-      new http.MultipartFile.fromBytes('file', [104, 101, 108, 108, 111])
+      new http.MultipartFile('file', [104, 101, 108, 108, 111])
     ];
     var request = new http.Request.multipart(dummyUrl, files: files);
 

From 04d482f01ef64b9fa2b646123ca0db5ae4e6dff6 Mon Sep 17 00:00:00 2001
From: Don <don.j.olmstead@gmail.com>
Date: Wed, 25 Oct 2017 16:59:12 -0700
Subject: [PATCH 17/20] Formating

---
 lib/src/multipart_file.dart | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/lib/src/multipart_file.dart b/lib/src/multipart_file.dart
index c53ad7c265..e6a9f97efb 100644
--- a/lib/src/multipart_file.dart
+++ b/lib/src/multipart_file.dart
@@ -50,10 +50,7 @@ class MultipartFile {
       defaultMediaType = new MediaType('application', 'octet-stream');
     } else {
       throw new ArgumentError.value(
-          value,
-          'value',
-          'value must be either a '
-          'String or a List<int>');
+          value, 'value', 'value must be either a String or a List<int>');
     }
 
     contentType ??= _lookupMediaType(filename, bytes) ?? defaultMediaType;
@@ -89,8 +86,8 @@ class MultipartFile {
   /// Can only be called once.
   Stream<List<int>> read() {
     if (_stream == null) {
-      throw new StateError("The 'read' method can only be called once on a "
-          "http.MultipartFile object.");
+      throw new StateError('The "read" method can only be called once on a '
+          'http.MultipartFile object.');
     }
     var stream = _stream;
     _stream = null;

From 7246b9ac1adcba6d38077877d9dad2d4d3f83320 Mon Sep 17 00:00:00 2001
From: Don <don.j.olmstead@gmail.com>
Date: Thu, 26 Oct 2017 12:32:34 -0700
Subject: [PATCH 18/20] Add readAsBytes to Message

---
 lib/src/message.dart | 13 +++++++++++--
 test/utils.dart      |  2 +-
 2 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/lib/src/message.dart b/lib/src/message.dart
index ae16e24963..6111027948 100644
--- a/lib/src/message.dart
+++ b/lib/src/message.dart
@@ -5,6 +5,7 @@
 import 'dart:async';
 import 'dart:convert';
 
+import 'package:async/async.dart';
 import 'package:collection/collection.dart';
 import 'package:http_parser/http_parser.dart';
 
@@ -121,16 +122,24 @@ abstract class Message {
 
   /// Returns the message body as byte chunks.
   ///
-  /// Throws a [StateError] if [read] or [readAsString] has already been called.
+  /// Throws a [StateError] if [read] or [readAsBytes] or [readAsString] has
+  /// already been called.
   Stream<List<int>> read() => _body.read();
 
+  /// Returns the message body as a list of bytes.
+  ///
+  /// Throws a [StateError] if [read] or [readAsBytes] or [readAsString] has
+  /// already been called.
+  Future<List<int>> readAsBytes() => collectBytes(read());
+
   /// Returns the message body as a string.
   ///
   /// If [encoding] is passed, that's used to decode the body. Otherwise the
   /// encoding is taken from the Content-Type header. If that doesn't exist or
   /// doesn't have a "charset" parameter, UTF-8 is used.
   ///
-  /// Throws a [StateError] if [read] or [readAsString] has already been called.
+  /// Throws a [StateError] if [read] or [readAsBytes] or [readAsString] has
+  /// already been called.
   Future<String> readAsString([Encoding encoding]) {
     encoding ??= this.encoding ?? UTF8;
     return encoding.decodeStream(read());
diff --git a/test/utils.dart b/test/utils.dart
index 72e77791ec..bf8da3a2d4 100644
--- a/test/utils.dart
+++ b/test/utils.dart
@@ -84,7 +84,7 @@ class _MultipartBodyMatches extends Matcher {
   bool matches(item, Map matchState) {
     if (item is! http.Request) return false;
 
-    var future = collectBytes(item.read()).then((bodyBytes) {
+    var future = item.readAsBytes().then((bodyBytes) {
       var body = UTF8.decode(bodyBytes);
       var contentType = new MediaType.parse(item.headers['content-type']);
       var boundary = contentType.parameters['boundary'];

From 05350c1284ac7c3ec1d084d66ebb819fa4389123 Mon Sep 17 00:00:00 2001
From: Don <don.j.olmstead@gmail.com>
Date: Thu, 26 Oct 2017 12:32:50 -0700
Subject: [PATCH 19/20] Fix nits

---
 lib/src/multipart_file.dart | 39 +++++++++++++++++++++++++++++++------
 pubspec.yaml                |  2 +-
 test/multipart_test.dart    |  4 +++-
 3 files changed, 37 insertions(+), 8 deletions(-)

diff --git a/lib/src/multipart_file.dart b/lib/src/multipart_file.dart
index e6a9f97efb..de75371c01 100644
--- a/lib/src/multipart_file.dart
+++ b/lib/src/multipart_file.dart
@@ -35,14 +35,25 @@ class MultipartFile {
   /// Defaults to `application/octet-stream`.
   final MediaType contentType;
 
+  /// Creates a [MultipartFile] from the [value].
   ///
+  /// [value] can be either a [String] or a [List<int>].
+  ///
+  /// For a String [value] the content will be encoded using [encoding] which
+  /// defaults to [UTF8]. The `charset` from [contentType] is ignored when
+  /// encoding the String.
+  ///
+  /// [contentType] if not specified will attempt to be looked up from the
+  /// bytes contained within the [stream] and the [filename] if provided. It
+  /// will default to `plain/text` for [String]s and `application/octet-stream`
+  /// for [List<int>].
   factory MultipartFile(String field, value,
       {String filename, MediaType contentType, Encoding encoding}) {
     List<int> bytes;
     var defaultMediaType;
 
     if (value is String) {
-      encoding ??= encodingForMediaType(contentType) ?? UTF8;
+      encoding ??= UTF8;
       bytes = encoding.encode(value);
       defaultMediaType = new MediaType('text', 'plain');
     } else if (value is List<int>) {
@@ -53,25 +64,40 @@ class MultipartFile {
           value, 'value', 'value must be either a String or a List<int>');
     }
 
-    contentType ??= _lookupMediaType(filename, bytes) ?? defaultMediaType;
+    contentType ??= _lookUpMediaType(filename, bytes) ?? defaultMediaType;
 
     if (encoding != null) {
       contentType = contentType.change(parameters: {'charset': encoding.name});
     }
 
     return new MultipartFile.fromStream(
-        field, new Stream<List<int>>.fromIterable([bytes]), bytes.length,
+        field, new Stream.fromIterable([bytes]), bytes.length,
         filename: filename, contentType: contentType);
   }
 
+  /// Creates a new [MultipartFile] from a chunked [stream] of bytes.
+  ///
+  /// The [length] of the file in bytes must be known in advance. If it's not
+  /// then use [loadStream] to create the [MultipartFile] instance.
+  ///
+  /// [contentType] if not specified will attempt to be looked up from the
+  /// [filename] if provided. It will default to `application/octet-stream`.
   MultipartFile.fromStream(this.field, Stream<List<int>> stream, this.length,
       {String filename, MediaType contentType})
       : _stream = stream,
         filename = filename,
         contentType = contentType ??
-            _lookupMediaType(filename) ??
+            _lookUpMediaType(filename) ??
             new MediaType('application', 'octet-stream');
 
+  /// Creates a new [MultipartFile] from the [stream].
+  ///
+  /// This method should be used when the length of [stream] in bytes is not
+  /// known ahead of time.
+  ///
+  /// [contentType] if not specified will attempt to be looked up from the
+  /// bytes contained within the [stream] and the [filename] if provided. It
+  /// will default to `application/octet-stream`.
   static Future<MultipartFile> loadStream(
       String field, Stream<List<int>> stream,
       {String filename, MediaType contentType}) async {
@@ -96,11 +122,12 @@ class MultipartFile {
 
   /// Looks up the [MediaType] from the [filename]'s extension or from
   /// magic numbers contained within a file header's [bytes].
-  static MediaType _lookupMediaType(String filename, [List<int> bytes]) {
-    if ((filename == null) && (bytes == null)) return null;
+  static MediaType _lookUpMediaType(String filename, [List<int> bytes]) {
+    if (filename == null && bytes == null) return null;
 
     // lookupMimeType expects filename to be non-null but its possible that
     // this can be called with bytes but no filename.
+    // FIXME: https://github.com/dart-lang/mime/issues/11
     var mimeType = lookupMimeType(filename ?? '', headerBytes: bytes);
 
     return mimeType != null ? new MediaType.parse(mimeType) : null;
diff --git a/pubspec.yaml b/pubspec.yaml
index 1c3ebefa2f..fbe50ba65e 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -7,7 +7,7 @@ dependencies:
   async: "^1.13.0"
   collection: "^1.5.0"
   http_parser: ">=0.0.1 <4.0.0"
-  mime: ">=0.9.0 < 1.0.0"
+  mime: "^0.9.0"
   typed_data: "^1.0.0"
 dev_dependencies:
   test: "^0.12.18"
diff --git a/test/multipart_test.dart b/test/multipart_test.dart
index d3302d0930..7e539f5da0 100644
--- a/test/multipart_test.dart
+++ b/test/multipart_test.dart
@@ -3,6 +3,7 @@
 // BSD-style license that can be found in the LICENSE file.
 
 import 'dart:async';
+import 'dart:convert';
 
 import 'package:http/http.dart' as http;
 import 'package:http_parser/http_parser.dart';
@@ -179,8 +180,9 @@ void main() {
     // "Ã¥" encoded as ISO-8859-1 and then read as UTF-8 results in "å".
     var files = [
       new http.MultipartFile('file', 'non-ascii: "Ã¥"',
+          encoding: LATIN1,
           contentType:
-              new MediaType('text', 'plain', {'charset': 'iso-8859-1'}))
+              new MediaType('text', 'plain'))
     ];
     var request = new http.Request.multipart(dummyUrl, files: files);
 

From d6be80407a255b033b7906fc7a4fd8f0a5b2c665 Mon Sep 17 00:00:00 2001
From: Don <don.j.olmstead@gmail.com>
Date: Thu, 26 Oct 2017 12:38:02 -0700
Subject: [PATCH 20/20] More nits

---
 lib/src/multipart_body.dart | 12 ++++++++----
 lib/src/request.dart        |  5 +++--
 2 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/lib/src/multipart_body.dart b/lib/src/multipart_body.dart
index f546e78b2b..961db27973 100644
--- a/lib/src/multipart_body.dart
+++ b/lib/src/multipart_body.dart
@@ -11,9 +11,10 @@ import 'body.dart';
 import 'multipart_file.dart';
 import 'utils.dart';
 
-/// A `multipart/form-data` request [Body]. Such a request has both string
-/// fields, which function as normal form fields, and (potentially streamed)
-/// binary files.
+/// A `multipart/form-data` request [Body].
+///
+/// Such a request has both string fields, which function as normal form
+/// fields, and (potentially streamed) binary files.
 class MultipartBody implements Body {
   /// The contents of the message body.
   ///
@@ -104,11 +105,14 @@ class MultipartBody implements Body {
       List<int> ending) async {
     for (var i = 0; i < files.length; ++i) {
       controller.add(fileHeaders[i]);
+
+      // file.read() can throw synchronously
       try {
         await writeStreamToSink(files[i].read(), controller);
-      } on Exception catch (exception, stackTrace) {
+      } catch (exception, stackTrace) {
         controller.addError(exception, stackTrace);
       }
+
       controller.add([13, 10]);
     }
 
diff --git a/lib/src/request.dart b/lib/src/request.dart
index 5e45428d6e..c50f018648 100644
--- a/lib/src/request.dart
+++ b/lib/src/request.dart
@@ -131,8 +131,9 @@ class Request extends Message {
       {Map<String, String> headers, Map<String, Object> context})
       : this('DELETE', url, headers: headers, context: context);
 
-  /// Creates a new `multipart/form-data` [Request] to [url], which can be a
-  /// [Uri] or a [String].
+  /// Creates a new
+  /// [`multipart/form-data`](https://en.wikipedia.org/wiki/MIME#Multipart_messages)
+  /// [Request] to [url], which can be a [Uri] or a [String].
   ///
   /// The content of the body is specified through the values of [fields] and
   /// [files].