Add histograms for FTP server types encountered by users.

This should help with decision which FTP server types we can safely stop supporting.

TEST=none
BUG=none

Review URL: http://codereview.chromium.org/176020

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@24824 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 81 insertions, 0 deletions

diff --git a/net/ftp/ftp_server_type_histograms.cc b/net/ftp/ftp_server_type_histograms.cc
new file mode 100644
index 0000000..3f419a8
--- /dev/null
+++ b/net/ftp/ftp_server_type_histograms.cc
@@ -0,0 +1,43 @@
+// Copyright (c) 2009 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 "net/ftp/ftp_server_type_histograms.h"
+
+#include "base/histogram.h"
+
+namespace net {
+
+// We're using a histogram as a group of counters.  We're only interested in
+// the values of the counters.  Ignore the shape, average, and standard
+// deviation of the histograms because they are meaningless.
+//
+// We use two groups of counters.  In the first group (counter1), each counter
+// is a boolean (0 or 1) that indicates whether the user has seen an FTP server
+// of that type during that session.  In the second group (counter2), each
+// counter is the number of transactions with FTP server of that type the user
+// has made during that session.
+//
+// Each histogram has an unused bucket at the end to allow seamless future
+// expansion.
+void UpdateFtpServerTypeHistograms(FtpServerType type) {
+  static bool had_server_type[NUM_OF_SERVER_TYPES];
+  static LinearHistogram counter1("Net.HadFtpServerType",
+                                  1, NUM_OF_SERVER_TYPES,
+                                  NUM_OF_SERVER_TYPES + 1);
+  static LinearHistogram counter2("Net.FtpServerTypeCount",
+                                  1, NUM_OF_SERVER_TYPES,
+                                  NUM_OF_SERVER_TYPES + 1);
+
+  if (type >= 0 && type < NUM_OF_SERVER_TYPES) {
+    if (!had_server_type[type]) {
+      had_server_type[type] = true;
+      counter1.SetFlags(kUmaTargetedHistogramFlag);
+      counter1.Add(type);
+    }
+  }
+  counter2.SetFlags(kUmaTargetedHistogramFlag);
+  counter2.Add(type);
+}
+
+}  // namespace net
diff --git a/net/ftp/ftp_server_type_histograms.h b/net/ftp/ftp_server_type_histograms.h
new file mode 100644
index 0000000..08ca424
--- /dev/null
+++ b/net/ftp/ftp_server_type_histograms.h
@@ -0,0 +1,38 @@
+// Copyright (c) 2009 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.
+
+#ifndef NET_FTP_FTP_SERVER_TYPE_HISTOGRAMS_H_
+#define NET_FTP_FTP_SERVER_TYPE_HISTOGRAMS_H_
+
+// The UpdateFtpServerTypeHistograms function collects statistics related
+// to the types of FTP servers that our users are encountering.  The
+// information will help us decide for what servers we can safely drop support.
+// The parsing code for each type of server is very complex, which poses a
+// security risk. In fact, in current shape it's a disaster waiting to happen.
+
+namespace net {
+
+enum FtpServerType {
+  // Record cases in which we couldn't parse the server's response. That means
+  // a server type we don't recognize, a security attack (when what we're
+  // connecting to isn't an FTP server), or a broken server.
+  SERVER_UNKNOWN = 0,
+
+  SERVER_LSL = 1,   // Server using /bin/ls -l and variants.
+  SERVER_DLS = 2,   // Server using /bin/dls.
+  SERVER_EPLF = 3,  // Server using EPLF format.
+  SERVER_DOS = 4,   // WinNT server configured for old style listing.
+  SERVER_VMS = 5,   // VMS (including variants).
+  SERVER_CMS = 6,   // IBM VM/CMS, VM/ESA, z/VM formats.
+  SERVER_OS2 = 7,   // OS/2 FTP Server.
+  SERVER_W16 = 8,   // win16 hosts: SuperTCP or NetManage Chameleon.
+
+  NUM_OF_SERVER_TYPES
+};
+
+void UpdateFtpServerTypeHistograms(FtpServerType type);
+
+}  // namespace net
+
+#endif  // NET_FTP_FTP_SERVER_TYPE_HISTOGRAMS_H_