Add HTTPMultipartBuilder and its test.

util/net/http_multipart_builder.cc

Index: util/net/http_multipart_builder.cc
diff --git a/util/net/http_multipart_builder.cc b/util/net/http_multipart_builder.cc
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+// Copyright 2014 The Crashpad Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "util/net/http_multipart_builder.h"
+
+#include <vector>
+
+#include "base/logging.h"
+#include "base/rand_util.h"
+#include "base/strings/stringprintf.h"
+#include "util/net/http_body.h"
+
+namespace crashpad {
+
+namespace {
+
+const char kCRLF[] = "\r\n";
+
+const char kBoundaryCRLF[] = "\r\n\r\n";
+
+// Generates a random string suitable for use as a multipart boundary.
+std::string GenerateBoundaryString() {
+  // RFC 2046 §5.1.1 says that the boundary string may be 1 to 70 characters
+  // long, choosing from the set of alphanumeric characters along with
+  // characters from the set “'()+_,-./:=? ”, and not ending in a space.
+  // However, some servers have been observed as dealing poorly with certain
+  // nonalphanumeric characters. See
+  // blink/Source/platform/network/FormDataBuilder.cpp
+  // blink::FormDataBuilder::generateUniqueBoundaryString().
+  //
+  // This implementation produces a 56-character string with over 190 bits of
+  // randomness (62^32 > 2^190).
+  std::string boundary_string = "---MultipartBoundary-";
+  for (int index = 0; index < 32; ++index) {
+    const char kCharacters[] =
+        "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
+    int random_value = base::RandGenerator(strlen(kCharacters));
+    boundary_string += kCharacters[random_value];
+  }
+  boundary_string += "---";
+  return boundary_string;
+}
+
+// Escapes the specified name to be suitable for the name field of a
+// form-data part.
+std::string EncodeMIMEField(const std::string& name) {
+  // RFC 2388 §3 says to encode non-ASCII field names according to RFC 2047, but
+  // no browsers implement that behavior. Instead, they send field names in the
+  // page hosting the form’s encoding. However, some form of escaping is needed.
+  // This URL-escapes the quote character and newline characters, per Blink. See
+  // blink/Source/platform/network/FormDataBuilder.cpp
+  // blink::appendQuotedString().
+  //
+  // TODO(mark): This encoding is not necessarily correct, and the same code in
+  // Blink is marked with a FIXME. Blink does not escape the '%' character,
+  // that’s a local addition, but it seems appropriate to be able to decode the
+  // string properly.
+  std::string encoded;
+  for (char character : name) {
+    switch (character) {
+      case '\r':
+      case '\n':
+      case '"':
+      case '%':
+        encoded += base::StringPrintf("%%%02x", character);
+        break;
+      default:
+        encoded += character;
+        break;
+    }
+  }
+
+  return encoded;
+}
+
+// Returns a string, formatted with a multipart boundary and a field name,
+// after which the contents of the part at |name| can be appended.
+std::string GetFormDataBoundary(const std::string& boundary,
+                                const std::string& name) {
+  return base::StringPrintf(
+      "--%s%sContent-Disposition: form-data; name=\"%s\"",
+      boundary.c_str(),
+      kCRLF,
+      EncodeMIMEField(name).c_str());
+}
+
+void AssertSafeMIMEType(const std::string& string) {
+  for (size_t i = 0; i < string.length(); ++i) {
+    char c = string[i];
+    CHECK((c >= 'a' && c <= 'z') ||
+          (c >= 'A' && c <= 'Z') ||
+          (c >= '0' && c <= '9') ||
+          c == '/' ||
+          c == '.' ||
+          c == '_' ||
+          c == '-');

[Mark Mentovai, 2014/10/29 23:13:59]

You need '+' also. application/xml+xhtml, for example.

+  }
+}
+
+}  // namespace
+
+HTTPMultipartBuilder::HTTPMultipartBuilder()
+    : boundary_(GenerateBoundaryString()), form_data_(), file_attachments_() {
+}
+
+HTTPMultipartBuilder::~HTTPMultipartBuilder() {
+}
+
+void HTTPMultipartBuilder::SetFormData(const std::string& key,
+                                       const std::string& value) {
+  EraseKey(key);
+  form_data_[key] = value;
+}
+
+void HTTPMultipartBuilder::SetFileAttachment(
+    const std::string& key,
+    const std::string& upload_file_name,
+    const base::FilePath& path,
+    const std::string& content_type) {
+  EraseKey(upload_file_name);
+
+  FileAttachment attachment;
+  attachment.filename = EncodeMIMEField(upload_file_name);
+  attachment.path = path;
+
+  if (content_type.empty()) {
+    attachment.content_type = "application/octet-stream";
+  } else {
+    AssertSafeMIMEType(content_type);
+    attachment.content_type = content_type;
+  }
+
+  file_attachments_[key] = attachment;
+}
+
+scoped_ptr<HTTPBodyStream> HTTPMultipartBuilder::GetBodyStream() {
+  // The objects inserted into this vector will be owned by the returned
+  // CompositeHTTPBodyStream. Take care to not early-return without deleting
+  // this memory.
+  std::vector<HTTPBodyStream*> streams;
+
+  for (const auto& pair : form_data_) {
+    std::string field = GetFormDataBoundary(boundary(), pair.first);
+    field += kBoundaryCRLF;
+    field += pair.second;
+    field += kCRLF;
+    streams.push_back(new StringHTTPBodyStream(field));
+  }
+
+  for (const auto& pair : file_attachments_) {
+    const FileAttachment& attachment = pair.second;
+    std::string header = GetFormDataBoundary(boundary(), pair.first);
+    header += base::StringPrintf("; filename=\"%s\"%s",
+        attachment.filename.c_str(), kCRLF);
+    header += base::StringPrintf("Content-Type: %s%s",
+        attachment.content_type.c_str(), kBoundaryCRLF);
+
+    streams.push_back(new StringHTTPBodyStream(header));
+    streams.push_back(new FileHTTPBodyStream(attachment.path));
+    streams.push_back(new StringHTTPBodyStream(kCRLF));
+  }
+
+  streams.push_back(
+      new StringHTTPBodyStream("--"  + boundary() + "--" + kCRLF));
+
+  return scoped_ptr<HTTPBodyStream>(new CompositeHTTPBodyStream(streams));
+}
+
+void HTTPMultipartBuilder::EraseKey(const std::string& key) {
+  auto data_it = form_data_.find(key);
+  if (data_it != form_data_.end())
+    form_data_.erase(data_it);
+
+  auto file_it = file_attachments_.find(key);
+  if (file_it != file_attachments_.end())
+    file_attachments_.erase(file_it);
+}
+
+}  // namespace crashpad