// 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/proxy/proxy_config_service_linux.h"

#include <gconf/gconf-client.h>
#include <stdlib.h>

#include "base/logging.h"
#include "base/string_tokenizer.h"
#include "base/string_util.h"
#include "base/task.h"
#include "googleurl/src/url_canon.h"
#include "net/base/net_errors.h"
#include "net/http/http_util.h"
#include "net/proxy/proxy_config.h"
#include "net/proxy/proxy_server.h"

namespace net {

namespace {

class EnvironmentVariableGetterImpl
    : public ProxyConfigServiceLinux::EnvironmentVariableGetter {
 public:
  virtual bool Getenv(const char* variable_name, std::string* result) {
    const char* env_value = ::getenv(variable_name);
    if (env_value) {
      // Note that the variable may be defined but empty.
      *result = env_value;
      return true;
    }
    // Some commonly used variable names are uppercase while others
    // are lowercase, which is inconsistent. Let's try to be helpful
    // and look for a variable name with the reverse case.
    char first_char = variable_name[0];
    std::string alternate_case_var;
    if (first_char >= 'a' && first_char <= 'z')
      alternate_case_var = StringToUpperASCII(std::string(variable_name));
    else if (first_char >= 'A' && first_char <= 'Z')
      alternate_case_var = StringToLowerASCII(std::string(variable_name));
    else
      return false;
    env_value = ::getenv(alternate_case_var.c_str());
    if (env_value) {
      *result = env_value;
      return true;
    }
    return false;
  }
};

// Given a proxy hostname from a setting, returns that hostname with
// an appropriate proxy server scheme prefix.
// scheme indicates the desired proxy scheme: usually http, with
// socks 4 or 5 as special cases.
std::string FixupProxyHostScheme(ProxyServer::Scheme scheme,
                                 std::string host) {
  if (scheme == ProxyServer::SCHEME_SOCKS4 &&
      StartsWithASCII(host, "socks5://", false)) {
    // We default to socks 4, but if the user specifically set it to
    // socks5://, then use that.
    scheme = ProxyServer::SCHEME_SOCKS5;
  }
  // Strip the scheme if any.
  std::string::size_type colon = host.find("://");
  if (colon != std::string::npos)
    host = host.substr(colon + 3);
  // If a username and perhaps password are specified, give a warning.
  std::string::size_type at_sign = host.find("@");
  // Should this be supported?
  if (at_sign != std::string::npos) {
    LOG(ERROR) << "Proxy authentication not supported";
    // Disregard the authentication parameters and continue with this hostname.
    host = host.substr(at_sign + 1);
  }
  // If this is a socks proxy, prepend a scheme so as to tell
  // ProxyServer. This also allows ProxyServer to choose the right
  // default port.
  if (scheme == ProxyServer::SCHEME_SOCKS4)
    host = "socks4://" + host;
  else if (scheme == ProxyServer::SCHEME_SOCKS5)
    host = "socks5://" + host;
  return host;
}

}  // namespace

bool ProxyConfigServiceLinux::Delegate::GetProxyFromEnvVarForScheme(
    const char* variable, ProxyServer::Scheme scheme,
    ProxyServer* result_server) {
  std::string env_value;
  if (env_var_getter_->Getenv(variable, &env_value)) {
    if (!env_value.empty()) {
      env_value = FixupProxyHostScheme(scheme, env_value);
      ProxyServer proxy_server = ProxyServer::FromURI(env_value);
      if (proxy_server.is_valid() && !proxy_server.is_direct()) {
        *result_server = proxy_server;
        return true;
      } else {
        LOG(ERROR) << "Failed to parse environment variable " << variable;
      }
    }
  }
  return false;
}

bool ProxyConfigServiceLinux::Delegate::GetProxyFromEnvVar(
    const char* variable, ProxyServer* result_server) {
  return GetProxyFromEnvVarForScheme(variable, ProxyServer::SCHEME_HTTP,
                                     result_server);
}

bool ProxyConfigServiceLinux::Delegate::GetConfigFromEnv(ProxyConfig* config) {
  // Check for automatic configuration first, in
  // "auto_proxy". Possibly only the "environment_proxy" firefox
  // extension has ever used this, but it still sounds like a good
  // idea.
  std::string auto_proxy;
  if (env_var_getter_->Getenv("auto_proxy", &auto_proxy)) {
    if (auto_proxy.empty()) {
      // Defined and empty => autodetect
      config->auto_detect = true;
    } else {
      // specified autoconfig URL
      config->pac_url = GURL(auto_proxy);
    }
    return true;
  }
  // "all_proxy" is a shortcut to avoid defining {http,https,ftp}_proxy.
  ProxyServer proxy_server;
  if (GetProxyFromEnvVar("all_proxy", &proxy_server)) {
    config->proxy_rules.type = ProxyConfig::ProxyRules::TYPE_SINGLE_PROXY;
    config->proxy_rules.single_proxy = proxy_server;
  } else {
    bool have_http = GetProxyFromEnvVar("http_proxy", &proxy_server);
    if (have_http)
      config->proxy_rules.proxy_for_http = proxy_server;
    // It would be tempting to let http_proxy apply for all protocols
    // if https_proxy and ftp_proxy are not defined. Googling turns up
    // several documents that mention only http_proxy. But then the
    // user really might not want to proxy https. And it doesn't seem
    // like other apps do this. So we will refrain.
    bool have_https = GetProxyFromEnvVar("https_proxy", &proxy_server);
    if (have_https)
      config->proxy_rules.proxy_for_https = proxy_server;
    bool have_ftp = GetProxyFromEnvVar("ftp_proxy", &proxy_server);
    if (have_ftp)
      config->proxy_rules.proxy_for_ftp = proxy_server;
    if (have_http || have_https || have_ftp) {
      // mustn't change type unless some rules are actually set.
      config->proxy_rules.type = ProxyConfig::ProxyRules::TYPE_PROXY_PER_SCHEME;
    }
  }
  if (config->proxy_rules.empty()) {
    // If the above were not defined, try for socks.
    ProxyServer::Scheme scheme = ProxyServer::SCHEME_SOCKS4;
    std::string env_version;
    if (env_var_getter_->Getenv("SOCKS_VERSION", &env_version)
        && env_version == "5")
      scheme = ProxyServer::SCHEME_SOCKS5;
    if (GetProxyFromEnvVarForScheme("SOCKS_SERVER", scheme, &proxy_server)) {
      config->proxy_rules.type = ProxyConfig::ProxyRules::TYPE_SINGLE_PROXY;
      config->proxy_rules.single_proxy = proxy_server;
    }
  }
  // Look for the proxy bypass list.
  std::string no_proxy;
  env_var_getter_->Getenv("no_proxy", &no_proxy);
  if (config->proxy_rules.empty()) {
    // Having only "no_proxy" set, presumably to "*", makes it
    // explicit that env vars do specify a configuration: having no
    // rules specified only means the user explicitly asks for direct
    // connections.
    return !no_proxy.empty();
  }
  config->ParseNoProxyList(no_proxy);
  return true;
}

namespace {

// static
// gconf notification callback, dispatched from the default
// glib main loop.
void OnGConfChangeNotification(
    GConfClient* client, guint cnxn_id,
    GConfEntry* entry, gpointer user_data) {
  // It would be nice to debounce multiple callbacks in quick
  // succession, since I guess we'll get one for each changed key. As
  // it is we will read settings from gconf once for each callback.
  LOG(INFO) << "gconf change notification for key "
            << gconf_entry_get_key(entry);
  // We don't track which key has changed, just that something did change.
  // Forward to a method on the proxy config service delegate object.
  ProxyConfigServiceLinux::Delegate* config_service_delegate =
      reinterpret_cast<ProxyConfigServiceLinux::Delegate*>(user_data);
  config_service_delegate->OnCheckProxyConfigSettings();
}

class GConfSettingGetterImpl
    : public ProxyConfigServiceLinux::GConfSettingGetter {
 public:
  GConfSettingGetterImpl() : client_(NULL), loop_(NULL) {}

  virtual ~GConfSettingGetterImpl() {
    LOG(INFO) << "~GConfSettingGetterImpl called";
    // client_ should have been released before now, from
    // Delegate::OnDestroy(), while running on the UI thread.
    DCHECK(!client_);
  }

  virtual bool Init() {
    DCHECK(!client_);
    DCHECK(!loop_);
    loop_ = MessageLoopForUI::current();
    client_ = gconf_client_get_default();
    if (!client_) {
      // It's not clear whether/when this can return NULL.
      LOG(ERROR) << "Unable to create a gconf client";
      loop_ = NULL;
      return false;
    }
    GError* error = NULL;
    // We need to add the directories for which we'll be asking
    // notifications, and we might as well ask to preload them.
    gconf_client_add_dir(client_, "/system/proxy",
                         GCONF_CLIENT_PRELOAD_ONELEVEL, &error);
    if (error == NULL) {
      gconf_client_add_dir(client_, "/system/http_proxy",
                           GCONF_CLIENT_PRELOAD_ONELEVEL, &error);
    }
    if (error != NULL) {
      LOG(ERROR) << "Error requesting gconf directory: " << error->message;
      g_error_free(error);
      Release();
      return false;
    }
    return true;
  }

  void Release() {
    if (client_) {
      DCHECK(MessageLoop::current() == loop_);
      // This also disables gconf notifications.
      g_object_unref(client_);
      client_ = NULL;
      loop_ = NULL;
    }
  }

  bool SetupNotification(void* callback_user_data) {
    DCHECK(client_);
    DCHECK(MessageLoop::current() == loop_);
    GError* error = NULL;
    gconf_client_notify_add(
        client_, "/system/proxy",
        OnGConfChangeNotification, callback_user_data,
        NULL, &error);
    if (error == NULL) {
      gconf_client_notify_add(
          client_, "/system/http_proxy",
          OnGConfChangeNotification, callback_user_data,
          NULL, &error);
    }
    if (error != NULL) {
      LOG(ERROR) << "Error requesting gconf notifications: " << error->message;
      g_error_free(error);
      Release();
      return false;
    }
    return true;
  }

  virtual bool GetString(const char* key, std::string* result) {
    DCHECK(client_);
    DCHECK(MessageLoop::current() == loop_);
    GError* error = NULL;
    gchar* value = gconf_client_get_string(client_, key, &error);
    if (HandleGError(error, key))
      return false;
    if (!value)
      return false;
    *result = value;
    g_free(value);
    return true;
  }
  virtual bool GetBoolean(const char* key, bool* result) {
    DCHECK(client_);
    DCHECK(MessageLoop::current() == loop_);
    GError* error = NULL;
    // We want to distinguish unset values from values defaulting to
    // false. For that we need to use the type-generic
    // gconf_client_get() rather than gconf_client_get_bool().
    GConfValue* gconf_value = gconf_client_get(client_, key, &error);
    if (HandleGError(error, key))
      return false;
    if (!gconf_value) {
      // Unset.
      return false;
    }
    if (gconf_value->type != GCONF_VALUE_BOOL) {
      gconf_value_free(gconf_value);
      return false;
    }
    gboolean bool_value = gconf_value_get_bool(gconf_value);
    *result = static_cast<bool>(bool_value);
    gconf_value_free(gconf_value);
    return true;
  }
  virtual bool GetInt(const char* key, int* result) {
    DCHECK(client_);
    DCHECK(MessageLoop::current() == loop_);
    GError* error = NULL;
    int value = gconf_client_get_int(client_, key, &error);
    if (HandleGError(error, key))
      return false;
    // We don't bother to distinguish an unset value because callers
    // don't care. 0 is returned if unset.
    *result = value;
    return true;
  }
  virtual bool GetStringList(const char* key,
                             std::vector<std::string>* result) {
    DCHECK(client_);
    DCHECK(MessageLoop::current() == loop_);
    GError* error = NULL;
    GSList* list = gconf_client_get_list(client_, key,
                                         GCONF_VALUE_STRING, &error);
    if (HandleGError(error, key))
      return false;
    if (!list) {
      // unset
      return false;
    }
    for (GSList *it = list; it; it = it->next) {
      result->push_back(static_cast<char*>(it->data));
      g_free(it->data);
    }
    g_slist_free(list);
    return true;
  }

 private:
  // Logs and frees a glib error. Returns false if there was no error
  // (error is NULL).
  bool HandleGError(GError* error, const char* key) {
    if (error != NULL) {
      LOG(ERROR) << "Error getting gconf value for " << key
                 << ": " << error->message;
      g_error_free(error);
      return true;
    }
    return false;
  }

  GConfClient* client_;

  // Message loop of the thread that we make gconf calls on. It should
  // be the UI thread and all our methods should be called on this
  // thread. Only for assertions.
  MessageLoop* loop_;

  DISALLOW_COPY_AND_ASSIGN(GConfSettingGetterImpl);
};

}  // namespace

bool ProxyConfigServiceLinux::Delegate::GetProxyFromGConf(
    const char* key_prefix, bool is_socks, ProxyServer* result_server) {
  std::string key(key_prefix);
  std::string host;
  if (!gconf_getter_->GetString((key + "host").c_str(), &host)
      || host.empty()) {
    // Unset or empty.
    return false;
  }
  // Check for an optional port.
  int port;
  gconf_getter_->GetInt((key + "port").c_str(), &port);
  if (port != 0) {
    // If a port is set and non-zero:
    host += ":" + IntToString(port);
  }
  host = FixupProxyHostScheme(
      is_socks ? ProxyServer::SCHEME_SOCKS4 : ProxyServer::SCHEME_HTTP,
      host);
  ProxyServer proxy_server = ProxyServer::FromURI(host);
  if (proxy_server.is_valid()) {
    *result_server = proxy_server;
    return true;
  }
  return false;
}

bool ProxyConfigServiceLinux::Delegate::GetConfigFromGConf(
    ProxyConfig* config) {
  std::string mode;
  if (!gconf_getter_->GetString("/system/proxy/mode", &mode)) {
    // We expect this to always be set, so if we don't see it then we
    // probably have a gconf problem, and so we don't have a valid
    // proxy config.
    return false;
  }
  if (mode == "none") {
    // Specifically specifies no proxy.
    return true;
  }

  if (mode == "auto") {
    // automatic proxy config
    std::string pac_url_str;
    if (gconf_getter_->GetString("/system/proxy/autoconfig_url",
                                 &pac_url_str)) {
      if (!pac_url_str.empty()) {
        GURL pac_url(pac_url_str);
        if (!pac_url.is_valid())
          return false;
        config->pac_url = pac_url;
        return true;
      }
    }
    config->auto_detect = true;
    return true;
  }

  if (mode != "manual") {
    // Mode is unrecognized.
    return false;
  }
  bool use_http_proxy;
  if (gconf_getter_->GetBoolean("/system/http_proxy/use_http_proxy",
                                &use_http_proxy)
      && !use_http_proxy) {
    // Another master switch for some reason. If set to false, then no
    // proxy. But we don't panic if the key doesn't exist.
    return true;
  }

  bool same_proxy = false;
  // Indicates to use the http proxy for all protocols. This one may
  // not exist (presumably on older versions), assume false in that
  // case.
  gconf_getter_->GetBoolean("/system/http_proxy/use_same_proxy",
                            &same_proxy);

  ProxyServer proxy_server;
  if (!same_proxy) {
    // Try socks.
    if (GetProxyFromGConf("/system/proxy/socks_", true, &proxy_server)) {
      // gconf settings do not appear to distinguish between socks
      // version. We default to version 4.
      config->proxy_rules.type = ProxyConfig::ProxyRules::TYPE_SINGLE_PROXY;
      config->proxy_rules.single_proxy = proxy_server;
    }
  }
  if (config->proxy_rules.empty()) {
    bool have_http = GetProxyFromGConf("/system/http_proxy/", false,
                                       &proxy_server);
    if (same_proxy) {
      if (have_http) {
        config->proxy_rules.type = ProxyConfig::ProxyRules::TYPE_SINGLE_PROXY;
        config->proxy_rules.single_proxy = proxy_server;
      }
    } else {
      // Protocol specific settings.
      if (have_http)
        config->proxy_rules.proxy_for_http = proxy_server;
      bool have_secure = GetProxyFromGConf("/system/proxy/secure_", false,
                                           &proxy_server);
      if (have_secure)
        config->proxy_rules.proxy_for_https = proxy_server;
      bool have_ftp = GetProxyFromGConf("/system/proxy/ftp_", false,
                                        &proxy_server);
      if (have_ftp)
        config->proxy_rules.proxy_for_ftp = proxy_server;
      if (have_http || have_secure || have_ftp)
        config->proxy_rules.type =
            ProxyConfig::ProxyRules::TYPE_PROXY_PER_SCHEME;
    }
  }

  if (config->proxy_rules.empty()) {
    // Manual mode but we couldn't parse any rules.
    return false;
  }

  // Check for authentication, just so we can warn.
  bool use_auth;
  gconf_getter_->GetBoolean("/system/http_proxy/use_authentication",
                            &use_auth);
  if (use_auth)
    LOG(ERROR) << "Proxy authentication not supported";

  // Now the bypass list.
  gconf_getter_->GetStringList("/system/http_proxy/ignore_hosts",
                               &config->proxy_bypass);
  // Note that there are no settings with semantics corresponding to
  // config->proxy_bypass_local_names.

  return true;
}

ProxyConfigServiceLinux::Delegate::Delegate(
    EnvironmentVariableGetter* env_var_getter,
    GConfSettingGetter* gconf_getter)
    : env_var_getter_(env_var_getter), gconf_getter_(gconf_getter),
      glib_default_loop_(NULL), io_loop_(NULL) {
}

bool ProxyConfigServiceLinux::Delegate::ShouldTryGConf() {
  // GNOME_DESKTOP_SESSION_ID being defined is a good indication that
  // we are probably running under GNOME.
  // Note: KDE_FULL_SESSION is a corresponding env var to recognize KDE.
  std::string dummy, desktop_session;
  return env_var_getter_->Getenv("GNOME_DESKTOP_SESSION_ID", &dummy)
      || (env_var_getter_->Getenv("DESKTOP_SESSION", &desktop_session)
          && desktop_session == "gnome");
  // I (sdoyon) would have liked to prioritize environment variables
  // and only fallback to gconf if env vars were unset. But
  // gnome-terminal "helpfully" sets http_proxy and no_proxy, and it
  // does so even if the proxy mode is set to auto, which would
  // mislead us.
  //
  // We could introduce a CHROME_PROXY_OBEY_ENV_VARS variable...??
}

void ProxyConfigServiceLinux::Delegate::SetupAndFetchInitialConfig(
    MessageLoop* glib_default_loop, MessageLoop* io_loop) {
  // We should be running on the default glib main loop thread right
  // now. gconf can only be accessed from this thread.
  DCHECK(MessageLoop::current() == glib_default_loop);
  glib_default_loop_ = glib_default_loop;
  io_loop_ = io_loop;

  // If we are passed a NULL io_loop, then we don't setup gconf
  // notifications. This should not be the usual case but is intended
  // to simplify test setups.
  if (!io_loop_)
    LOG(INFO) << "Monitoring of gconf setting changes is disabled";

  // Fetch and cache the current proxy config. The config is left in
  // cached_config_, where GetProxyConfig() running on the IO thread
  // will expect to find it. This is safe to do because we return
  // before this ProxyConfigServiceLinux is passed on to
  // the ProxyService.
  bool got_config = false;
  if (ShouldTryGConf() &&
      gconf_getter_->Init() &&
      (!io_loop || gconf_getter_->SetupNotification(this))) {
    if (GetConfigFromGConf(&cached_config_)) {
      cached_config_.set_id(1);  // mark it as valid
      got_config = true;
      LOG(INFO) << "Obtained proxy setting from gconf";
      // If gconf proxy mode is "none", meaning direct, then we take
      // that to be a valid config and will not check environment
      // variables.  The alternative would have been to look for a proxy
      // where ever we can find one.
      //
      // Keep a copy of the config for use from this thread for
      // comparison with updated settings when we get notifications.
      reference_config_ = cached_config_;
      reference_config_.set_id(1);  // mark it as valid
    } else {
      gconf_getter_->Release();  // Stop notifications
    }
  }
  if (!got_config) {
    // An implementation for KDE settings would be welcome here.
    //
    // Consulting environment variables doesn't need to be done from
    // the default glib main loop, but it's a tiny enough amount of
    // work.
    if (GetConfigFromEnv(&cached_config_)) {
      cached_config_.set_id(1);  // mark it as valid
      LOG(INFO) << "Obtained proxy setting from environment variables";
    }
  }
}

void ProxyConfigServiceLinux::Delegate::Reset() {
  DCHECK(!glib_default_loop_ || MessageLoop::current() == glib_default_loop_);
  gconf_getter_->Release();
  cached_config_ = ProxyConfig();
}

int ProxyConfigServiceLinux::Delegate::GetProxyConfig(ProxyConfig* config) {
  // This is called from the IO thread.
  DCHECK(!io_loop_ || MessageLoop::current() == io_loop_);

  // Simply return the last proxy configuration that glib_default_loop
  // notified us of.
  *config = cached_config_;
  return cached_config_.is_valid() ? OK : ERR_FAILED;
}

void ProxyConfigServiceLinux::Delegate::OnCheckProxyConfigSettings() {
  // This should be dispatched from the thread with the default glib
  // main loop, which allows us to access gconf.
  DCHECK(MessageLoop::current() == glib_default_loop_);

  ProxyConfig new_config;
  bool valid = GetConfigFromGConf(&new_config);
  if (valid)
    new_config.set_id(1);  // mark it as valid

  // See if it is different than what we had before.
  if (new_config.is_valid() != reference_config_.is_valid() ||
      !new_config.Equals(reference_config_)) {
    // Post a task to |io_loop| with the new configuration, so it can
    // update |cached_config_|.
    io_loop_->PostTask(
        FROM_HERE,
        NewRunnableMethod(
            this,
            &ProxyConfigServiceLinux::Delegate::SetNewProxyConfig,
            new_config));
  }
}

void ProxyConfigServiceLinux::Delegate::SetNewProxyConfig(
    const ProxyConfig& new_config) {
  DCHECK(MessageLoop::current() == io_loop_);
  LOG(INFO) << "Proxy configuration changed";
  cached_config_ = new_config;
}

void ProxyConfigServiceLinux::Delegate::PostDestroyTask() {
  if (MessageLoop::current() == glib_default_loop_) {
    // Already on the right thread, call directly.
    // This is the case for the unittests.
    OnDestroy();
  } else {
    // Post to UI thread. Note that on browser shutdown, we may quit
    // the UI MessageLoop and exit the program before ever running
    // this.
    glib_default_loop_->PostTask(
        FROM_HERE,
        NewRunnableMethod(
            this,
            &ProxyConfigServiceLinux::Delegate::OnDestroy));
  }
}
void ProxyConfigServiceLinux::Delegate::OnDestroy() {
  DCHECK(!glib_default_loop_ || MessageLoop::current() == glib_default_loop_);
  gconf_getter_->Release();
}

ProxyConfigServiceLinux::ProxyConfigServiceLinux()
    : delegate_(new Delegate(new EnvironmentVariableGetterImpl(),
                             new GConfSettingGetterImpl())) {
}

ProxyConfigServiceLinux::ProxyConfigServiceLinux(
    EnvironmentVariableGetter* env_var_getter,
    GConfSettingGetter* gconf_getter)
    : delegate_(new Delegate(env_var_getter, gconf_getter)) {
}

}  // namespace net