crash-reporter: Create a list_proxies command

get_proxies.cc

+// Copyright (c) 2011 The Chromium OS 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 <deque>
+#include <string>
+
+#include <chromeos/dbus/dbus.h>

[kmixter1, 2011/03/24 17:24:34]

existing style is to put this in ""s with the other ChromeOS-specific includes.

[Michael Krebs, 2011/04/05 01:12:03]

Done.

+#include <dbus/dbus-glib-lowlevel.h>
+#include <glib.h>
+
+#include "base/basictypes.h"
+#include "base/command_line.h"
+#include "base/json/json_reader.h"

[kmixter1, 2011/03/24 17:24:34]

abc order

[Michael Krebs, 2011/04/05 01:12:03]

Done.

+#include "base/file_util.h"
+#include "base/logging.h"
+#include "base/string_tokenizer.h"
+#include "base/string_util.h"
+#include "base/values.h"
+#include "chromeos/syslog_logging.h"
+#include "gflags/gflags.h"
+
+
+#pragma GCC diagnostic ignored "-Wstrict-aliasing"
+DEFINE_bool(force_session_proxies, false, "Print list of session proxies");
+DEFINE_bool(force_browser_proxies, false, "Print list of browser proxies");
+DEFINE_bool(quiet, false, "Only print the proxies");
+#pragma GCC diagnostic error "-Wstrict-aliasing"
+
+
+const char kNoProxy[] = "direct://";
+
+// For ShowBrowserProxies()
+const char kLibCrosServiceName[] = "org.chromium.LibCrosService";
+const char kLibCrosServicePath[] = "/org/chromium/LibCrosService";
+const char kLibCrosServiceInterface[] = "org.chromium.LibCrosServiceInterface";
+const char kLibCrosServiceResolveNetworkProxyMethodName[] =
+    "ResolveNetworkProxy";
+const char kLibCrosProxyResolveName[] = "ProxyResolved";
+const char kLibCrosProxyResolveSignalInterface[] =
+    "org.chromium.CrashReporterLibcrosProxyResolvedInterface";
+
+// For ShowSessionProxies()

[kmixter1, 2011/03/24 17:24:34]

Why do we need to get the proxy setting directly from session_manager -
shouldn't Chrome correctly decide when to use that?

[Michael Krebs, 2011/04/05 01:12:03]

This is in case Chrome is unavailable/not responding.

+const char kSessionManagerService[] = "org.chromium.SessionManager";
+const char kSessionManagerPath[] = "/org/chromium/SessionManager";
+const char kSessionManagerInterface[] = "org.chromium.SessionManagerInterface";
+const char kSessionManagerRetrievePropertyMethod[] = "RetrieveProperty";
+const char kSessionManagerProxySettingsKey[] = "cros.proxy.everywhere";
+
+
+// Number of seconds to wait for browser to send us a signal
+const int kBrowserTimeout = 5;
+
+
+#define TEST_AND_RETURN_FALSE(_x)                                              \
+  do {                                                                         \
+    bool _success = (_x);                                                      \
+    if (!_success) {                                                           \
+      LOG(ERROR) << #_x " failed.";                                            \
+      return false;                                                            \
+    }                                                                          \
+  } while (0)
+
+static bool StringHasPrefix(const std::string& str, const std::string& prefix) {
+  if (prefix.size() > str.size())
+    return false;
+  return 0 == str.compare(0, prefix.size(), prefix);
+}
+
+static const char* GetGErrorMessage(const GError* error) {
+  if (!error)
+    return "Unknown error.";
+  return error->message;
+}
+
+
+bool PrinterrAndLog(const char *format, ...) {
+  va_list ap;
+  va_start(ap, format);
+  const gchar *buffer = g_strdup_vprintf(format, ap);
+  va_end(ap);
+  LOG(ERROR) << buffer;
+  if (!FLAGS_quiet)
+    g_printerr("%s\n", buffer);
+  return false;
+}
+
+
+// Copied from src/update_engine/chrome_browser_proxy_resolver.cc
+std::deque<std::string> ParseProxyString(const std::string &input) {

[kmixter1, 2011/03/24 17:24:34]

This should eventually be moved into a library in src/common.  Comment
eventually should say it validates the proxy string returned and the format of
input.

[Michael Krebs, 2011/04/05 01:12:03]

Should I do anything with this function for this CL?

+  std::deque<std::string> ret;
+  // Some of this code taken from
+  // http://src.chromium.org/svn/trunk/src/net/proxy/proxy_server.cc and
+  // http://src.chromium.org/svn/trunk/src/net/proxy/proxy_list.cc
+  StringTokenizer entry_tok(input, ";");
+  while (entry_tok.GetNext()) {
+    std::string token = entry_tok.token();
+    TrimWhitespaceASCII(token, TRIM_ALL, &token);
+
+    // Start by finding the first space (if any).
+    std::string::iterator space;
+    for (space = token.begin(); space != token.end(); ++space) {
+      if (IsAsciiWhitespace(*space)) {
+        break;
+      }
+    }
+
+    std::string scheme = std::string(token.begin(), space);
+    StringToLowerASCII(&scheme);
+    // Chrome uses "socks" to mean socks4 and "proxy" to mean http.
+    if (scheme == "socks")
+      scheme += "4";
+    else if (scheme == "proxy")
+      scheme = "http";
+    else if (scheme != "https" &&
+             scheme != "socks4" &&
+             scheme != "socks5" &&
+             scheme != "direct")
+      continue;  // Invalid proxy scheme
+
+    std::string host_and_port = std::string(space, token.end());
+    TrimWhitespaceASCII(host_and_port, TRIM_ALL, &host_and_port);
+    if (scheme != "direct" && host_and_port.empty())
+      continue;  // Must supply host/port when non-direct proxy used.
+    ret.push_back(scheme + "://" + host_and_port);
+  }
+  if (ret.empty() || *ret.rbegin() != kNoProxy)
+    ret.push_back(kNoProxy);
+  return ret;
+}
+
+class BrowserProxyResolvedSignalWatcher : public chromeos::dbus::SignalWatcher {

[kmixter1, 2011/03/24 17:24:34]

I think I've run into a simpler way to do this with dbus alone (you can do a
blocking call to return the next signal and handle it in your own main loop).

[Michael Krebs, 2011/04/05 01:12:03]

I can't find the simpler way to do this.  Could you be thinking of being able to
block for the D-Bus reply (i.e. not a signal)?

If I understand D-Bus correctly, I think dbus_g_proxy_call() will invoke a
method on the remote interface, and then block waiting for the reply (as opposed
to dbus_g_proxy_begin_call(), which does it asynchronously).  The way the
proxy-resolving works, though, is not to return the result in the D-Bus reply,
but instead have Chrome invoke a new D-Bus signal on our interface with the
response as its arguments.

+ public:
+  explicit BrowserProxyResolvedSignalWatcher(GMainLoop *main_loop,
+                                             std::deque<std::string> *proxies)
+      : main_loop_(main_loop), proxies_(proxies) { }
+
+  virtual void OnSignal(DBusMessage *message) {
+    // Get args
+    char *source_url = NULL;
+    char *proxy_list = NULL;
+    char *error = NULL;
+    DBusError arg_error;
+    dbus_error_init(&arg_error);
+    if (!dbus_message_get_args(message, &arg_error,
+                               DBUS_TYPE_STRING, &source_url,
+                               DBUS_TYPE_STRING, &proxy_list,
+                               DBUS_TYPE_STRING, &error,
+                               DBUS_TYPE_INVALID)) {
+      PrinterrAndLog("Error reading D-Bus signal");
+      return;
+    }
+    if (!source_url || !proxy_list) {
+      PrinterrAndLog("Error getting url, proxy list from D-Bus signal");

[kmixter1, 2011/03/24 17:24:34]

Why isn't this just LOG(ERROR)?

[Michael Krebs, 2011/04/05 01:12:03]

Done.

+      return;
+    }
+
+    const std::deque<std::string> &proxies = ParseProxyString(proxy_list);
+    for (std::deque<std::string>::const_iterator it = proxies.begin();
+         it != proxies.end(); ++it) {
+      LOG(INFO) << "Browser signal add: " << (*it).c_str();
+      proxies_->push_back(*it);
+    }
+
+    g_main_loop_quit(main_loop_);
+  }
+
+ private:
+  GMainLoop *main_loop_;
+  std::deque<std::string> *proxies_;
+};
+
+static gboolean HandleBrowserTimeout(void *data) {
+  GMainLoop *main_loop = reinterpret_cast<GMainLoop *>(data);
+  PrinterrAndLog("Timeout while waiting for browser to resolve proxy");
+  g_main_loop_quit(main_loop);
+  return false;  // only call once
+}
+
+static bool ShowBrowserProxies(const char *url) {
+  GMainLoop *main_loop = g_main_loop_new(NULL, false);
+
+  chromeos::dbus::BusConnection dbus = chromeos::dbus::GetSystemBusConnection();
+  chromeos::dbus::Proxy browser_proxy(dbus,
+                                      kLibCrosServiceName,
+                                      kLibCrosServicePath,
+                                      kLibCrosServiceInterface);
+  if (!browser_proxy.gproxy()) {
+    PrinterrAndLog("Error creating proxy to D-Bus interface '%s'",
+                   kLibCrosServiceName);
+    return false;
+  }
+
+  // Watch for a proxy-resolved signal sent to us
+  std::deque<std::string> proxies;
+  BrowserProxyResolvedSignalWatcher proxy_resolver(main_loop, &proxies);
+  proxy_resolver.StartMonitoring(kLibCrosProxyResolveSignalInterface,
+                                 kLibCrosProxyResolveName);
+
+  // Request the proxies for our URL.  The answer is sent to us via a
+  // proxy-resolved signal.
+  GError *gerror = NULL;
+  if (!dbus_g_proxy_call(browser_proxy.gproxy(),
+                         kLibCrosServiceResolveNetworkProxyMethodName,
+                         &gerror,
+                         G_TYPE_STRING, url,
+                         G_TYPE_STRING, kLibCrosProxyResolveSignalInterface,
+                         G_TYPE_STRING, kLibCrosProxyResolveName,
+                         G_TYPE_INVALID, G_TYPE_INVALID)) {
+    PrinterrAndLog("Error performing D-Bus proxy call '%s': %s",
+                   kLibCrosServiceResolveNetworkProxyMethodName,
+                   GetGErrorMessage(gerror));
+    return false;
+  }
+
+  // Setup a timeout in case the browser doesn't respond with our signal
+  g_timeout_add_seconds(kBrowserTimeout, &HandleBrowserTimeout, main_loop);
+
+  // Loop until we either get the proxy-resolved signal, or until the
+  // timeout is reached.
+  g_main_loop_run(main_loop);
+
+  for (std::deque<std::string>::const_iterator it = proxies.begin();
+       it != proxies.end(); ++it) {
+    if (!FLAGS_quiet)
+      g_print("Browser proxy: ");
+    g_print("%s\n", (*it).c_str());
+  }
+
+  return true;
+}
+
+
+namespace {
+enum ProxyMode {
+  kProxyModeDirect = 0,
+  kProxyModeAutoDetect = 1,
+  kProxyModePACScript = 2,
+  kProxyModeSingle = 3,
+  kProxyModeProxyPerScheme = 4
+};
+}  // namespace {}
+
+// Copied from src/update_engine/chrome_proxy_resolver.cc
+bool GetProxiesForUrlWithSettings(const char *url,

[kmixter1, 2011/03/24 17:24:34]

Needs docs.  What is json_settings besides json?

[Michael Krebs, 2011/04/05 01:12:03]

Done.

+                                  const char *json_settings,
+                                  std::deque<std::string> *out_proxies) {
+  base::JSONReader parser;
+
+  out_proxies->clear();
+
+  scoped_ptr<Value> root(
+      parser.JsonToValue(json_settings,
+                         true,  // check root is obj/arr
+                         false));  // false = disallow trailing comma
+  if (!root.get()) {
+    PrinterrAndLog("Unable to parse \"%s\": %s", json_settings,
+                   parser.GetErrorMessage().c_str());
+    return false;
+  }
+
+  TEST_AND_RETURN_FALSE(root->IsType(Value::TYPE_DICTIONARY));

[kmixter1, 2011/03/24 17:24:34]

I really don't like macros that have control flow embedded in them.  Suggest
expanding to a one-liner if statement at least.

[Michael Krebs, 2011/04/05 01:12:03]

Done.

+
+  DictionaryValue* root_dict = dynamic_cast<DictionaryValue*>(root.get());
+  TEST_AND_RETURN_FALSE(root_dict);
+  int mode = -1;
+  TEST_AND_RETURN_FALSE(root_dict->GetInteger("mode", &mode));
+
+  // TODO(mkrebs): This ignores any "bypass_rules" setting.
+  switch (mode) {
+    case kProxyModeDirect: {
+      // Do nothing.
+      break;
+    }
+
+    case kProxyModeSingle: {
+      LOG(INFO) << "single proxy mode";
+      std::string proxy_string;
+      if (!root_dict->GetString("single.server", &proxy_string)) {
+        PrinterrAndLog("Unable to find \"single.server\" key in "
+                       "session manager proxy message");
+        return false;
+      }
+      if (proxy_string.find("://") == std::string::npos) {
+        // missing protocol, assume http.
+        proxy_string = std::string("http://") + proxy_string;
+      }
+      out_proxies->push_back(proxy_string);
+      LOG(INFO) << "single proxy: " << (*out_proxies)[0];
+      break;
+    }
+
+    case kProxyModeProxyPerScheme: {
+      // Proxy per scheme mode.
+      LOG(INFO) << "proxy per scheme mode";
+
+      // Find which scheme we are.  An undefined URL defaults to "http://".

[kmixter1, 2011/03/24 17:24:34]

This should have been a separate function and an easy one to unit test.

[Michael Krebs, 2011/04/05 01:12:03]

Done.

+      bool url_is_http = !url || StringHasPrefix(url, "http://");
+      if (!url_is_http)
+        TEST_AND_RETURN_FALSE(StringHasPrefix(url, "https://"));
+
+      // Using "proto_*" variables to refer to http or https
+      const std::string proto_path = url_is_http ? "http.server" :
+          "https.server";
+      const std::string socks_path = "socks.server";
+
+      std::string proto_server, socks_server;
+      if (root_dict->GetString(proto_path, &proto_server)) {
+        if (proto_server.find("://") == std::string::npos) {
+          // missing protocol, assume http.
+          proto_server = std::string("http://") + proto_server;
+        }
+        out_proxies->push_back(proto_server);
+        LOG(INFO) << "got http/https server: " << proto_server;
+      }
+      if (root_dict->GetString(socks_path, &socks_server)) {
+        out_proxies->push_back(socks_server);
+        LOG(INFO) << "got socks server: " << proto_server;
+      }
+      break;
+    }
+
+    default: {
+      LOG(INFO) << "unsupported proxy mode: " << mode;
+      break;
+    }
+  }
+
+  // Always add direct proxy.
+  out_proxies->push_back(kNoProxy);
+  return true;
+}
+
+static bool ShowSessionProxies(const char *url) {
+  chromeos::dbus::BusConnection dbus = chromeos::dbus::GetSystemBusConnection();
+  chromeos::dbus::Proxy session_proxy(dbus,
+                                      kSessionManagerService,
+                                      kSessionManagerPath,
+                                      kSessionManagerInterface);
+  CHECK(session_proxy.gproxy());
+
+  // ChromeProxyResolver::GetProxiesForUrl()
+  std::deque<std::string> proxies;
+  // First, query dbus for the currently stored settings
+  // ChromeProxyResolver::GetJsonProxySettings()
+  gchar *json_settings = NULL;
+  GError *gerror = NULL;
+  GArray *sig = NULL;
+  if (!dbus_g_proxy_call(session_proxy.gproxy(),
+                      kSessionManagerRetrievePropertyMethod,
+                      &gerror,
+                      G_TYPE_STRING, kSessionManagerProxySettingsKey,
+                      G_TYPE_INVALID,
+                      G_TYPE_STRING, &json_settings,
+                      DBUS_TYPE_G_UCHAR_ARRAY, &sig,
+                      G_TYPE_INVALID)) {
+    PrinterrAndLog("Error retrieving property '%s' via D-Bus proxy call: %s",
+                   kSessionManagerProxySettingsKey,
+                   GetGErrorMessage(gerror));
+    return false;
+  }
+  g_array_free(sig, false);
+  LOG(INFO) << "Received session manager proxy settings: " << json_settings;
+  GetProxiesForUrlWithSettings(url, json_settings, &proxies);
+  g_free(json_settings);
+
+  for (std::deque<std::string>::const_iterator it = proxies.begin();
+       it != proxies.end(); ++it) {
+    if (!FLAGS_quiet)
+      g_print("Session manager proxy: ");
+    g_print("%s\n", (*it).c_str());
+  }
+  return true;
+}
+
+
+int main(int argc, char *argv[]) {
+  google::ParseCommandLineFlags(&argc, &argv, true);
+  FilePath my_path(argv[0]);
+  file_util::AbsolutePath(&my_path);
+  CommandLine::Init(argc, argv);
+  chromeos::OpenLog(my_path.BaseName().value().c_str(), true);

[kmixter1, 2011/03/24 17:24:34]

Doing OpenLog may not be necessary (and thus the other basename my_path stuff
goes away as well).

[Michael Krebs, 2011/04/05 01:12:03]

Done.

+  chromeos::InitLog(chromeos::kLogToSyslog);
+
+  ::g_type_init();
+
+  const char *url = (argc >= 2) ? argv[1] : NULL;
+
+  if (!FLAGS_quiet)
+    g_print("Resolving proxies for URL: %s\n", url);

[kmixter1, 2011/03/24 17:24:34]

do you plan to leave this in?  If so why not LOG(INFO)?

[Michael Krebs, 2011/04/05 01:12:03]

Done.

+
+  if (FLAGS_force_browser_proxies || FLAGS_force_session_proxies) {
+    if (FLAGS_force_browser_proxies)
+      ShowBrowserProxies(url);
+    if (FLAGS_force_session_proxies)
+      ShowSessionProxies(url);
+  } else {
+    if (!ShowBrowserProxies(url)) {
+      if (!ShowSessionProxies(url)) {
+        PrinterrAndLog("Error resolving proxies for URL '%s'", url);
+        if (!FLAGS_quiet)
+          g_print("Default proxy: ");
+        g_print("%s\n", kNoProxy);
+      }
+    }
+  }
+
+  return 0;
+}