Upstream various ios/web utilities and helpers

ios/web/net/request_group_util.mm

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "ios/web/net/request_group_util.h"
+
+#include <Foundation/Foundation.h>
+
+#include "base/base64.h"
+#include "base/logging.h"
+#include "base/rand_util.h"
+#include "base/strings/sys_string_conversions.h"
+#import "net/base/mac/url_conversions.h"
+#include "url/gurl.h"
+
+namespace {
+// Minimum length for a request group ID. A shorter string is considered as an
+// invalid ID.
+const int kMinimumIDLength = 5;
+}
+
+namespace web {
+
+// Generates a request-group ID used to correlate web requests with the embedder
+// that triggered it. It is important that the return value should not be unique
+// for different users. See crbug/355613 for context.
+NSString* GenerateNewRequestGroupID() {
+  const unsigned int kGroupSize = 1000;
+  static unsigned long count = 0;
+  static unsigned int offset = base::RandInt(0, kGroupSize - 1);
+
+  unsigned long current = count++;
+  if (current < kGroupSize)
+    current = (current + offset) % kGroupSize;
+
+  // The returned string must have a minimum of kMinimumIDLength characters, and
+  // no spaces.
+  // TODO(blundell): Develop a long-term solution to this problem.
+  // crbug.com/329243
+  return [NSString stringWithFormat:@"%06lu", current];
+}
+
+NSString* ExtractRequestGroupIDFromUserAgent(NSString* user_agent) {
+  if (![user_agent length])
+    return nil;
+
+  // The request_group_id is wrapped by parenthesis in the last space-delimited
+  // fragment.
+  NSString* fragment =
+      [[user_agent componentsSeparatedByString:@" "] lastObject];
+  NSString* request_group_id =
+      [fragment hasPrefix:@"("] && [fragment hasSuffix:@")"]
+          ? [fragment substringWithRange:NSMakeRange(1, [fragment length] - 2)]
+          : nil;
+  // GTLService constructs user agents that end with "(gzip)". To avoid these
+  // getting treated as having the request_group_id "gzip", short-circuit out if
+  // the request_group_id is not long enough to be a valid request_group_id (all
+  // valid request_group_id are at least kMinimumIDLength characters long).
+  // TODO(blundell): Develop a long-term solution to this problem.
+  // crbug.com/329243
+  if ([request_group_id length] < kMinimumIDLength)
+    return nil;
+  return request_group_id;
+}
+
+NSString* AddRequestGroupIDToUserAgent(NSString* base_user_agent,
+                                       NSString* request_group_id) {
+  // TODO(blundell): Develop a long-term solution to this problem.
+  // crbug.com/329243
+  DCHECK([request_group_id length] >= kMinimumIDLength);
+  return
+      [NSString stringWithFormat:@"%@ (%@)", base_user_agent, request_group_id];
+}
+
+NSString* ExtractRequestGroupIDFromURL(NSURL* url) {
+  GURL gurl = net::GURLWithNSURL(url);
+  if (!gurl.has_username())
+    return nil;
+
+  std::string request_group_id_as_string;
+  if (base::Base64Decode(gurl.username(), &request_group_id_as_string))
+    return base::SysUTF8ToNSString(request_group_id_as_string);
+
+  return nil;
+}
+
+NSURL* AddRequestGroupIDToURL(NSURL* base_url, NSString* request_group_id) {
+  GURL url = net::GURLWithNSURL(base_url);
+  std::string base64RequestGroupID;
+  base::Base64Encode(base::SysNSStringToUTF8(request_group_id),
+                     &base64RequestGroupID);
+  GURL::Replacements replacements;
+  replacements.SetUsernameStr(base64RequestGroupID);
+  url = url.ReplaceComponents(replacements);
+  return net::NSURLWithGURL(url);
+}
+
+NSString* ExtractRequestGroupIDFromRequest(NSURLRequest* request,
+                                           NSString* application_scheme) {
+  NSString* user_agent =
+      [[request allHTTPHeaderFields] objectForKey:@"User-Agent"];
+  NSString* request_group_id = ExtractRequestGroupIDFromUserAgent(user_agent);
+  if (request_group_id)
+    return request_group_id;
+  if (application_scheme &&
+      [[request.mainDocumentURL scheme]
+          caseInsensitiveCompare:application_scheme] == NSOrderedSame) {
+    return ExtractRequestGroupIDFromURL(request.mainDocumentURL);
+  }
+  return nil;
+}
+
+}  // namespace web