crash-reporter: Create a list_proxies command

get_proxies.cc

+// Copyright (c) 2011 The Chromium OS Authors. All rights reserved.

[kmixter1, 2011/04/12 01:17:41]

nit: I would probably choose print, list, or dump over "get" in the name of this
command.  It sounds more like a function name than a unix command, but this is
admittedly a nit.

[Michael Krebs, 2011/04/14 03:39:15]

Done.

+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include <unistd.h>  // for isatty()
+
+#include <deque>
+#include <string>
+
+#include <dbus/dbus-glib-lowlevel.h>
+#include <glib.h>
+
+#include "base/command_line.h"
+#include "base/file_util.h"
+#include "base/string_tokenizer.h"
+#include "base/string_util.h"
+#include "base/values.h"
+#include "chromeos/dbus/dbus.h"
+#include "chromeos/syslog_logging.h"
+#include "gflags/gflags.h"
+
+
+#pragma GCC diagnostic ignored "-Wstrict-aliasing"
+DEFINE_bool(quiet, false, "Only print the proxies");
+DEFINE_bool(verbose, false, "Print additional messages even "
+                            "when not run from a TTY");
+#pragma GCC diagnostic error "-Wstrict-aliasing"
+
+
+const char kNoProxy[] = "direct://";
+
+// The browser's method to call to resolve proxies.
+const char kLibCrosServiceName[] = "org.chromium.LibCrosService";
+const char kLibCrosServicePath[] = "/org/chromium/LibCrosService";
+const char kLibCrosServiceInterface[] = "org.chromium.LibCrosServiceInterface";
+const char kLibCrosServiceResolveNetworkProxyMethodName[] =
+    "ResolveNetworkProxy";
+// The signal the browser will send to us with its answer.
+const char kLibCrosProxyResolveSignalInterface[] =
+    "org.chromium.CrashReporterLibcrosProxyResolvedInterface";
+const char kLibCrosProxyResolveName[] = "ProxyResolved";
+
+

[kmixter1, 2011/04/12 01:17:41]

nit: I would avoid using extra vertical white space.  While the style guide is
not very exact about this, look around src/platform and I think you'll see 1
space is all that's used to separate sections of declarations and to separate
functions.

[Michael Krebs, 2011/04/14 03:39:15]

Done.

+// Number of seconds to wait for browser to send us a signal
+const int kBrowserTimeout = 5;

[kmixter1, 2011/04/12 01:17:41]

Should this be a DEFINE_int32 flag?

[Michael Krebs, 2011/04/14 03:39:15]

Done.

+
+
+static const char *GetGErrorMessage(const GError *error) {
+  if (!error)
+    return "Unknown error.";
+  return error->message;
+}
+
+
+// Copied from src/update_engine/chrome_browser_proxy_resolver.cc
+// Parses the browser's answer for resolved proxies.  It returns a
+// list of strings, each of which is a resolved proxy.
+std::deque<std::string> ParseProxyString(const std::string &input) {
+  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, 2011/04/12 01:17:41]

Add a basic class docstring.

[Michael Krebs, 2011/04/14 03:39:15]

Is the comment that's there now okay?  I couldn't find an example of a class
docstring elsewhere to mimic.

+ 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)) {
+      LOG(ERROR) << "Error reading D-Bus signal";
+      return;
+    }
+    if (!source_url || !proxy_list) {
+      LOG(ERROR) << "Error getting url, proxy list from D-Bus signal";
+      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) << "Found proxy via browser signal: " << (*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);
+  LOG(ERROR) << "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();
+  if (!dbus.HasConnection()) {
+    LOG(ERROR) << "Error connecting to system D-Bus";
+    return false;
+  }
+  chromeos::dbus::Proxy browser_proxy(dbus,
+                                      kLibCrosServiceName,
+                                      kLibCrosServicePath,
+                                      kLibCrosServiceInterface);
+  if (!browser_proxy) {
+    LOG(ERROR) << "Error creating D-Bus proxy to interface "
+               << "'" << 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)) {
+    LOG(ERROR) << "Error performing D-Bus proxy call "
+               << "'" << 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) {
+    g_print("%s\n", (*it).c_str());
+  }
+
+  return true;
+}
+
+
+int main(int argc, char *argv[]) {
+  google::ParseCommandLineFlags(&argc, &argv, true);
+  CommandLine::Init(argc, argv);
+
+  // Default to logging to syslog.
+  int init_flags = chromeos::kLogToSyslog;
+  // Log to stderr if a TTY (and "-quiet" wasn't passed), or if "-verbose"
+  // was passed.
+  if ((!FLAGS_quiet && isatty(STDERR_FILENO)) || FLAGS_verbose)
+    init_flags |= chromeos::kLogToStderr;
+  chromeos::InitLog(init_flags);
+
+  ::g_type_init();
+
+  const char *url = (argc >= 2) ? argv[1] : NULL;

[kmixter1, 2011/04/12 01:17:41]

Would generally say to
const char *url = NULL;
if (argc >= 2) {
  print resolving proxies for URL $argv[1]
  url = argv[1]
} else
  print resolving proxies without URL

avoids a pair of ?:'s and seems more readable.

[Michael Krebs, 2011/04/14 03:39:15]

Done.

+
+  LOG(INFO) << "Resolving proxies for URL: " << (url ? url : "<n/a>");

[kmixter1, 2011/04/12 01:17:41]

add explicit comparison to NULL for local style.

[Michael Krebs, 2011/04/14 03:39:15]

Moot after above change.

+
+  if (!ShowBrowserProxies(url)) {
+    LOG(ERROR) << "Error resolving proxies via the browser";
+    LOG(INFO) << "Assuming direct proxy";
+    g_print("%s\n", kNoProxy);

[kmixter1, 2011/04/12 01:17:41]

Why g_print vs printf?

[Michael Krebs, 2011/04/14 03:39:15]

Done.

+  }
+
+  return 0;
+}