Allow ClientTransportPlugins to use proxies

This change allows using Socks4Proxy, Socks5Proxy and HTTPSProxy with
ClientTransportPlugins via the TOR_PT_PROXY extension to the
pluggable transport specification.

This fixes bug #8402.

5 files changed, 251 insertions, 23 deletions

diff --git a/src/or/config.c b/src/or/config.c
index 0f7b1d2a2e..b33098e542 100644
--- a/src/or/config.c
+++ b/src/or/config.c
@@ -3174,11 +3174,11 @@ options_validate(or_options_t *old_options, or_options_t *options,
     }
   }
 
-  /* Check if more than one proxy type has been enabled. */
+  /* Check if more than one exclusive proxy type has been enabled. */
   if (!!options->Socks4Proxy + !!options->Socks5Proxy +
-      !!options->HTTPSProxy + !!options->ClientTransportPlugin > 1)
+      !!options->HTTPSProxy > 1)
     REJECT("You have configured more than one proxy type. "
-           "(Socks4Proxy|Socks5Proxy|HTTPSProxy|ClientTransportPlugin)");
+           "(Socks4Proxy|Socks5Proxy|HTTPSProxy)");
 
   /* Check if the proxies will give surprising behavior. */
   if (options->HTTPProxy && !(options->Socks4Proxy ||
@@ -4842,6 +4842,13 @@ parse_client_transport_line(const or_options_t *options,
       pt_kickstart_client_proxy(transport_list, proxy_argv);
     }
   } else { /* external */
+    /* ClientTransportPlugins connecting through a proxy is managed only. */
+    if (options->Socks4Proxy || options->Socks5Proxy || options->HTTPSProxy) {
+      log_warn(LD_CONFIG, "You have configured an external proxy with another "
+                          "proxy type. (Socks4Proxy|Socks5Proxy|HTTPSProxy)");
+      goto err;
+    }
+
     if (smartlist_len(transport_list) != 1) {
       log_warn(LD_CONFIG, "You can't have an external proxy with "
                "more than one transports.");
diff --git a/src/or/connection.c b/src/or/connection.c
index cef9172ff1..b32cddf1f1 100644
--- a/src/or/connection.c
+++ b/src/or/connection.c
@@ -86,6 +86,8 @@ static int connection_read_https_proxy_response(connection_t *conn);
 static void connection_send_socks5_connect(connection_t *conn);
 static const char *proxy_type_to_string(int proxy_type);
 static int get_proxy_type(void);
+static int get_bridge_pt_addrport(tor_addr_t *addr, uint16_t *port,
+                                  int *proxy_type, const connection_t *conn);
 
 /** The last addresses that our network interface seemed to have been
  * binding to.  We use this as one way to detect when our IP changes.
@@ -1689,14 +1691,14 @@ get_proxy_type(void)
 {
   const or_options_t *options = get_options();
 
-  if (options->HTTPSProxy)
+  if (options->ClientTransportPlugin)
+    return PROXY_PLUGGABLE;
+  else if (options->HTTPSProxy)
     return PROXY_CONNECT;
   else if (options->Socks4Proxy)
     return PROXY_SOCKS4;
   else if (options->Socks5Proxy)
     return PROXY_SOCKS5;
-  else if (options->ClientTransportPlugin)
-    return PROXY_PLUGGABLE;
   else
     return PROXY_NONE;
 }
@@ -4771,6 +4773,35 @@ assert_connection_ok(connection_t *conn, time_t now)
 }
 
 /** Fills <b>addr</b> and <b>port</b> with the details of the global
+ *  pluggable transport or bridge we are using.
+ *  <b>conn</b> contains the connection we are using the PT/bridge for.
+ *
+ * Return 0 on success, -1 on failure.
+ */
+static int
+get_bridge_pt_addrport(tor_addr_t *addr, uint16_t *port, int *proxy_type,
+                       const connection_t *conn)
+{
+  const or_options_t *options = get_options();
+
+  if (options->ClientTransportPlugin || options->Bridges) {
+    const transport_t *transport = NULL;
+    int r;
+    r = get_transport_by_bridge_addrport(&conn->addr, conn->port, &transport);
+    if (r<0)
+      return -1;
+    if (transport) { /* transport found */
+      tor_addr_copy(addr, &transport->addr);
+      *port = transport->port;
+      *proxy_type = transport->socks_version;
+      return 0;
+    }
+  }
+
+  return -1;
+}
+
+/** Fills <b>addr</b> and <b>port</b> with the details of the global
  *  proxy server we are using.
  *  <b>conn</b> contains the connection we are using the proxy for.
  *
@@ -4782,6 +4813,16 @@ get_proxy_addrport(tor_addr_t *addr, uint16_t *port, int *proxy_type,
 {
   const or_options_t *options = get_options();
 
+  /* Client Transport Plugins can use another proxy, but that should be hidden
+   * from the rest of tor (as the plugin is responsible for dealing with the
+   * proxy), check it first, then check the rest of the proxy types to allow
+   * the config to have unused ClientTransportPlugin entries.
+   */
+  if (options->ClientTransportPlugin) {
+    if (get_bridge_pt_addrport(addr, port, proxy_type, conn) == 0)
+      return 0;
+  }
+
   if (options->HTTPSProxy) {
     tor_addr_copy(addr, &options->HTTPSProxyAddr);
     *port = options->HTTPSProxyPort;
@@ -4797,19 +4838,8 @@ get_proxy_addrport(tor_addr_t *addr, uint16_t *port, int *proxy_type,
     *port = options->Socks5ProxyPort;
     *proxy_type = PROXY_SOCKS5;
     return 0;
-  } else if (options->ClientTransportPlugin ||
-             options->Bridges) {
-    const transport_t *transport = NULL;
-    int r;
-    r = get_transport_by_bridge_addrport(&conn->addr, conn->port, &transport);
-    if (r<0)
-      return -1;
-    if (transport) { /* transport found */
-      tor_addr_copy(addr, &transport->addr);
-      *port = transport->port;
-      *proxy_type = transport->socks_version;
-      return 0;
-    }
+  } else if (options->Bridges) {
+    return get_bridge_pt_addrport(addr, port, proxy_type, conn);
   }
 
   tor_addr_make_unspec(addr);
diff --git a/src/or/transports.c b/src/or/transports.c
index dc30754162..b810315d57 100644
--- a/src/or/transports.c
+++ b/src/or/transports.c
@@ -124,6 +124,8 @@ static INLINE void free_execve_args(char **arg);
 #define PROTO_SMETHOD_ERROR "SMETHOD-ERROR"
 #define PROTO_CMETHODS_DONE "CMETHODS DONE"
 #define PROTO_SMETHODS_DONE "SMETHODS DONE"
+#define PROTO_PROXY_DONE "PROXY DONE"
+#define PROTO_PROXY_ERROR "PROXY-ERROR"
 
 /** The first and only supported - at the moment - configuration
     protocol version. */
@@ -439,6 +441,17 @@ add_transport_to_proxy(const char *transport, managed_proxy_t *mp)
 static int
 proxy_needs_restart(const managed_proxy_t *mp)
 {
+  int ret = 1;
+  char* proxy_uri;
+
+  /* If the PT proxy config has changed, then all existing pluggable transports
+   * should be restarted.
+   */
+
+  proxy_uri = get_pt_proxy_uri();
+  if (strcmp_opt(proxy_uri, mp->proxy_uri) != 0)
+    goto needs_restart;
+
   /* mp->transport_to_launch is populated with the names of the
      transports that must be launched *after* the SIGHUP.
      mp->transports is populated with the transports that were
@@ -459,10 +472,10 @@ proxy_needs_restart(const managed_proxy_t *mp)
 
   } SMARTLIST_FOREACH_END(t);
 
-  return 0;
-
- needs_restart:
-  return 1;
+  ret = 0;
+needs_restart:
+  tor_free(proxy_uri);
+  return ret;
 }
 
 /** Managed proxy <b>mp</b> must be restarted. Do all the necessary
@@ -493,6 +506,11 @@ proxy_prepare_for_restart(managed_proxy_t *mp)
   SMARTLIST_FOREACH(mp->transports, transport_t *, t, transport_free(t));
   smartlist_clear(mp->transports);
 
+  /* Reset the proxy's HTTPS/SOCKS proxy */
+  tor_free(mp->proxy_uri);
+  mp->proxy_uri = get_pt_proxy_uri();
+  mp->proxy_supported = 0;
+
   /* flag it as an infant proxy so that it gets launched on next tick */
   mp->conf_state = PT_PROTO_INFANT;
   unconfigured_proxies_n++;
@@ -727,12 +745,52 @@ managed_proxy_destroy(managed_proxy_t *mp,
   /* free the argv */
   free_execve_args(mp->argv);
 
+  /* free the outgoing proxy URI */
+  tor_free(mp->proxy_uri);
+
   tor_process_handle_destroy(mp->process_handle, also_terminate_process);
   mp->process_handle = NULL;
 
   tor_free(mp);
 }
 
+/** Convert the tor proxy options to a URI suitable for TOR_PT_PROXY. */
+STATIC char *
+get_pt_proxy_uri(void)
+{
+  const or_options_t *options = get_options();
+  char *uri = NULL;
+
+  if (options->Socks4Proxy || options->Socks5Proxy || options->HTTPSProxy) {
+    char addr[TOR_ADDR_BUF_LEN+1];
+
+    if (options->Socks4Proxy) {
+      tor_addr_to_str(addr, &options->Socks4ProxyAddr, sizeof(addr), 1);
+      tor_asprintf(&uri, "socks4a://%s:%d", addr, options->Socks4ProxyPort);
+    } else if (options->Socks5Proxy) {
+      tor_addr_to_str(addr, &options->Socks5ProxyAddr, sizeof(addr), 1);
+      if (!options->Socks5ProxyUsername && !options->Socks5ProxyPassword) {
+        tor_asprintf(&uri, "socks5://%s:%d", addr, options->Socks5ProxyPort);
+      } else {
+        tor_asprintf(&uri, "socks5://%s:%s@%s:%d",
+                     options->Socks5ProxyUsername,
+                     options->Socks5ProxyPassword,
+                     addr, options->Socks5ProxyPort);
+      }
+    } else if (options->HTTPSProxy) {
+      tor_addr_to_str(addr, &options->HTTPSProxyAddr, sizeof(addr), 1);
+      if (!options->HTTPSProxyAuthenticator) {
+        tor_asprintf(&uri, "http://%s:%d", addr, options->HTTPSProxyPort);
+      } else {
+        tor_asprintf(&uri, "http://%s@%s:%d", options->HTTPSProxyAuthenticator,
+                     addr, options->HTTPSProxyPort);
+      }
+    }
+  }
+
+  return uri;
+}
+
 /** Handle a configured or broken managed proxy <b>mp</b>. */
 static void
 handle_finished_proxy(managed_proxy_t *mp)
@@ -745,6 +803,12 @@ handle_finished_proxy(managed_proxy_t *mp)
     managed_proxy_destroy(mp, 0); /* destroy it but don't terminate */
     break;
   case PT_PROTO_CONFIGURED: /* if configured correctly: */
+    if (mp->proxy_uri && !mp->proxy_supported) {
+      log_warn(LD_CONFIG, "Managed proxy '%s' did not configure the "
+               "specified outgoing proxy.", mp->argv[0]);
+      managed_proxy_destroy(mp, 1); /* annihilate it. */
+      break;
+    }
     register_proxy(mp); /* register its transports */
     mp->conf_state = PT_PROTO_COMPLETED; /* and mark it as completed. */
     break;
@@ -862,6 +926,22 @@ handle_proxy_line(const char *line, managed_proxy_t *mp)
       goto err;
 
     return;
+  } else if (!strcmpstart(line, PROTO_PROXY_DONE)) {
+    if (mp->conf_state != PT_PROTO_ACCEPTING_METHODS)
+      goto err;
+
+    if (mp->proxy_uri) {
+      mp->proxy_supported = 1;
+      return;
+    }
+
+    /* No proxy was configured, this should log */
+  } else if (!strcmpstart(line, PROTO_PROXY_ERROR)) {
+    if (mp->conf_state != PT_PROTO_ACCEPTING_METHODS)
+      goto err;
+
+    parse_proxy_error(line);
+    goto err;
   } else if (!strcmpstart(line, SPAWN_ERROR_MESSAGE)) {
     /* managed proxy launch failed: parse error message to learn why. */
     int retval, child_state, saved_errno;
@@ -1128,6 +1208,21 @@ parse_cmethod_line(const char *line, managed_proxy_t *mp)
   return r;
 }
 
+/** Parses an PROXY-ERROR <b>line</b> and warns the user accordingly. */
+STATIC void
+parse_proxy_error(const char *line)
+{
+  /* (Length of the protocol string) plus (a space) and (the first char of
+     the error message) */
+  if (strlen(line) < (strlen(PROTO_PROXY_ERROR) + 2))
+    log_notice(LD_CONFIG, "Managed proxy sent us an %s without an error "
+               "message.", PROTO_PROXY_ERROR);
+
+  log_warn(LD_CONFIG, "Managed proxy failed to configure the "
+           "pluggable transport's outgoing proxy. (%s)",
+           line+strlen(PROTO_PROXY_ERROR)+1);
+}
+
 /** Return a newly allocated string that tor should place in
  * TOR_PT_SERVER_TRANSPORT_OPTIONS while configuring the server
  * manged proxy in <b>mp</b>. Return NULL if no such options are found. */
@@ -1292,6 +1387,14 @@ create_managed_proxy_environment(const managed_proxy_t *mp)
     } else {
       smartlist_add_asprintf(envs, "TOR_PT_EXTENDED_SERVER_PORT=");
     }
+  } else {
+    /* If ClientTransportPlugin has a HTTPS/SOCKS proxy configured, set the
+     * TOR_PT_PROXY line.
+     */
+
+    if (mp->proxy_uri) {
+      smartlist_add_asprintf(envs, "TOR_PT_PROXY=%s", mp->proxy_uri);
+    }
   }
 
   SMARTLIST_FOREACH_BEGIN(envs, const char *, env_var) {
@@ -1324,6 +1427,7 @@ managed_proxy_create(const smartlist_t *transport_list,
   mp->is_server = is_server;
   mp->argv = proxy_argv;
   mp->transports = smartlist_new();
+  mp->proxy_uri = get_pt_proxy_uri();
 
   mp->transports_to_launch = smartlist_new();
   SMARTLIST_FOREACH(transport_list, const char *, transport,
diff --git a/src/or/transports.h b/src/or/transports.h
index 1365ead006..bc2331d01b 100644
--- a/src/or/transports.h
+++ b/src/or/transports.h
@@ -81,6 +81,9 @@ typedef struct {
   char **argv; /* the cli arguments of this proxy */
   int conf_protocol; /* the configuration protocol version used */
 
+  char *proxy_uri;  /* the outgoing proxy in TOR_PT_PROXY URI format */
+  int proxy_supported : 1; /* the proxy claims to honor TOR_PT_PROXY */
+
   int is_server; /* is it a server proxy? */
 
   /* A pointer to the process handle of this managed proxy. */
@@ -112,6 +115,7 @@ STATIC int parse_smethod_line(const char *line, managed_proxy_t *mp);
 
 STATIC int parse_version(const char *line, managed_proxy_t *mp);
 STATIC void parse_env_error(const char *line);
+STATIC void parse_proxy_error(const char *line);
 STATIC void handle_proxy_line(const char *line, managed_proxy_t *mp);
 STATIC char *get_transport_options_for_server_proxy(const managed_proxy_t *mp);
 
@@ -123,6 +127,8 @@ STATIC managed_proxy_t *managed_proxy_create(const smartlist_t *transport_list,
 
 STATIC int configure_proxy(managed_proxy_t *mp);
 
+STATIC char* get_pt_proxy_uri(void);
+
 #endif
 
 #endif
diff --git a/src/test/test_pt.c b/src/test/test_pt.c
index f71627df1e..788d4205cc 100644
--- a/src/test/test_pt.c
+++ b/src/test/test_pt.c
@@ -450,6 +450,85 @@ test_pt_configure_proxy(void *arg)
   tor_free(mp);
 }
 
+/* Test the get_pt_proxy_uri() function. */
+static void
+test_get_pt_proxy_uri(void *arg)
+{
+  or_options_t *options = get_options_mutable();
+  char *uri = NULL;
+  int ret;
+  (void) arg;
+
+  /* Test with no proxy. */
+  uri = get_pt_proxy_uri();
+  tt_assert(uri == NULL);
+
+  /* Test with a SOCKS4 proxy. */
+  options->Socks4Proxy = "192.0.2.1:1080";
+  ret = tor_addr_port_lookup(options->Socks4Proxy,
+                             &options->Socks4ProxyAddr,
+                             &options->Socks4ProxyPort);
+  tt_assert(ret == 0);
+  uri = get_pt_proxy_uri();
+  tt_str_op(uri, ==, "socks4a://192.0.2.1:1080");
+  tor_free(uri);
+
+  options->Socks4Proxy = NULL;
+
+  /* Test with a SOCKS5 proxy, no username/password. */
+  options->Socks5Proxy = "192.0.2.1:1080";
+  ret = tor_addr_port_lookup(options->Socks5Proxy,
+                             &options->Socks5ProxyAddr,
+                             &options->Socks5ProxyPort);
+  tt_assert(ret == 0);
+  uri = get_pt_proxy_uri();
+  tt_str_op(uri, ==, "socks5://192.0.2.1:1080");
+  tor_free(uri);
+
+  /* Test with a SOCKS5 proxy, with username/password. */
+  options->Socks5ProxyUsername = "hwest";
+  options->Socks5ProxyPassword = "r34n1m470r";
+  uri = get_pt_proxy_uri();
+  tt_str_op(uri, ==, "socks5://hwest:r34n1m470r@192.0.2.1:1080");
+  tor_free(uri);
+
+  options->Socks5Proxy = NULL;
+
+  /* Test with a HTTPS proxy, no authenticator. */
+  options->HTTPSProxy = "192.0.2.1:80";
+  ret = tor_addr_port_lookup(options->HTTPSProxy,
+                             &options->HTTPSProxyAddr,
+                             &options->HTTPSProxyPort);
+  tt_assert(ret == 0);
+  uri = get_pt_proxy_uri();
+  tt_str_op(uri, ==, "http://192.0.2.1:80");
+  tor_free(uri);
+
+  /* Test with a HTTPS proxy, with authenticator. */
+  options->HTTPSProxyAuthenticator = "hwest:r34n1m470r";
+  uri = get_pt_proxy_uri();
+  tt_str_op(uri, ==, "http://hwest:r34n1m470r@192.0.2.1:80");
+  tor_free(uri);
+
+  options->HTTPSProxy = NULL;
+
+  /* Token nod to the fact that IPv6 exists. */
+  options->Socks4Proxy = "[2001:db8::1]:1080";
+  ret = tor_addr_port_lookup(options->Socks4Proxy,
+                             &options->Socks4ProxyAddr,
+                             &options->Socks4ProxyPort);
+  tt_assert(ret == 0);
+  uri = get_pt_proxy_uri();
+  tt_str_op(uri, ==, "socks4a://[2001:db8::1]:1080");
+  tor_free(uri);
+
+
+ done:
+  if (uri)
+    tor_free(uri);
+}
+
+
 #define PT_LEGACY(name)                                               \
   { #name, legacy_test_helper, 0, &legacy_setup, test_pt_ ## name }
 
@@ -462,6 +541,8 @@ struct testcase_t pt_tests[] = {
     NULL, NULL },
   { "configure_proxy",test_pt_configure_proxy, TT_FORK,
     NULL, NULL },
+  { "get_pt_proxy_uri", test_get_pt_proxy_uri, TT_FORK,
+    NULL, NULL },
   END_OF_TESTCASES
 };