Add support for STATUS messages from Pluggable Transports.

This patch adds support for the new STATUS message that PT's can emit
from their standard out. The STATUS message uses the `config_line_t` K/V
format that was recently added in Tor.

See: https://bugs.torproject.org/28846

5 files changed, 92 insertions, 4 deletions

diff --git a/src/feature/client/transports.c b/src/feature/client/transports.c
index 6a3479a470..45dbd0c888 100644
--- a/src/feature/client/transports.c
+++ b/src/feature/client/transports.c
@@ -130,6 +130,7 @@ static void parse_method_error(const char *line, int is_server_method);
 #define PROTO_PROXY_DONE "PROXY DONE"
 #define PROTO_PROXY_ERROR "PROXY-ERROR"
 #define PROTO_LOG "LOG"
+#define PROTO_STATUS "STATUS"
 
 /** The first and only supported - at the moment - configuration
     protocol version. */
@@ -912,12 +913,16 @@ handle_proxy_line(const char *line, managed_proxy_t *mp)
     parse_proxy_error(line);
     goto err;
 
-    /* We check for the additional " " after the PROTO_LOG string to make sure
-     * we can later extend this big if/else-if table with something that begins
-     * with "LOG" without having to get the order right. */
+    /* We check for the additional " " after the PROTO_LOG * PROTO_STATUS
+     * string to make sure we can later extend this big if/else-if table with
+     * something that begins with "LOG" without having to get the order right.
+     * */
   } else if (!strcmpstart(line, PROTO_LOG " ")) {
     parse_log_line(line, mp);
     return;
+  } else if (!strcmpstart(line, PROTO_STATUS " ")) {
+    parse_status_line(line, mp);
+    return;
   }
 
   log_notice(LD_GENERAL, "Unknown line received by managed proxy (%s).", line);
@@ -1205,6 +1210,55 @@ parse_log_line(const char *line, managed_proxy_t *mp)
   tor_free(log_message);
 }
 
+/** Parses a STATUS <b>line</b> and emit control events accordingly. */
+STATIC void
+parse_status_line(const char *line, managed_proxy_t *mp)
+{
+  tor_assert(line);
+  tor_assert(mp);
+
+  config_line_t *values = NULL;
+  char *status_message = NULL;
+
+  if (strlen(line) < (strlen(PROTO_STATUS) + 1)) {
+    log_warn(LD_PT, "Managed proxy sent us a %s line "
+                    "with missing argument.", PROTO_STATUS);
+    goto done;
+  }
+
+  const char *data = line + strlen(PROTO_STATUS) + 1;
+
+  values = kvline_parse(data, KV_QUOTED);
+
+  if (! values) {
+    log_warn(LD_PT, "Managed proxy \"%s\" wrote an invalid "
+             "STATUS message: %s", mp->argv[0], data);
+    goto done;
+  }
+
+  /* We check if we received the TYPE parameter, which is the only *required*
+   * value. */
+  const config_line_t *type = config_line_find(values, "TYPE");
+
+  if (! type) {
+    log_warn(LD_PT, "Managed proxy \"%s\" wrote a STATUS line without "
+                    "TYPE: %s", mp->argv[0], data);
+    goto done;
+  }
+
+  /* Prepend the PT name. */
+  config_line_prepend(&values, "PT", mp->argv[0]);
+  status_message = kvline_encode(values, KV_QUOTED);
+
+  /* We have checked that TYPE is there, we can now emit the STATUS event via
+   * the control port. */
+  control_event_pt_status(status_message);
+
+ done:
+  config_free_lines(values);
+  tor_free(status_message);
+}
+
 /** 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. */
diff --git a/src/feature/client/transports.h b/src/feature/client/transports.h
index b8d1bb0081..1a910ae82c 100644
--- a/src/feature/client/transports.h
+++ b/src/feature/client/transports.h
@@ -129,6 +129,7 @@ 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 void parse_log_line(const char *line, managed_proxy_t *mp);
+STATIC void parse_status_line(const char *line, managed_proxy_t *mp);
 STATIC char *get_transport_options_for_server_proxy(const managed_proxy_t *mp);
 
 STATIC void managed_proxy_destroy(managed_proxy_t *mp,
diff --git a/src/feature/control/control.c b/src/feature/control/control.c
index 849f11707e..4ef550c919 100644
--- a/src/feature/control/control.c
+++ b/src/feature/control/control.c
@@ -7043,6 +7043,16 @@ control_event_pt_log(const char *log)
                      log);
 }
 
+/** A pluggable transport has emitted a STATUS message found in
+ * <b>status</b>. */
+void
+control_event_pt_status(const char *status)
+{
+  send_control_event(EVENT_PT_STATUS,
+                     "650 PT_STATUS %s\r\n",
+                     status);
+}
+
 /** Convert rendezvous auth type to string for HS_DESC control events
  */
 const char *
diff --git a/src/feature/control/control.h b/src/feature/control/control.h
index b3a2707672..d78ce4d87c 100644
--- a/src/feature/control/control.h
+++ b/src/feature/control/control.h
@@ -208,6 +208,7 @@ void control_event_transport_launched(const char *mode,
                                       const char *transport_name,
                                       tor_addr_t *addr, uint16_t port);
 void control_event_pt_log(const char *log);
+void control_event_pt_status(const char *status);
 const char *rend_auth_type_to_string(rend_auth_type_t auth_type);
 MOCK_DECL(const char *, node_describe_longname_by_id,(const char *id_digest));
 void control_event_hs_descriptor_requested(const char *onion_address,
@@ -297,7 +298,8 @@ void control_free_all(void);
 #define EVENT_HS_DESC_CONTENT         0x0022
 #define EVENT_NETWORK_LIVENESS        0x0023
 #define EVENT_PT_LOG                  0x0024
-#define EVENT_MAX_                    0x0024
+#define EVENT_PT_STATUS               0x0025
+#define EVENT_MAX_                    0x0025
 
 /* sizeof(control_connection_t.event_mask) in bits, currently a uint64_t */
 #define EVENT_CAPACITY_               0x0040
diff --git a/src/test/test_pt.c b/src/test/test_pt.c
index 271d74f26a..8de687c866 100644
--- a/src/test/test_pt.c
+++ b/src/test/test_pt.c
@@ -316,6 +316,10 @@ process_read_stdout_replacement(process_t *process, buf_t *buffer)
     buf_add_string(buffer, "LOG SEVERITY=notice MESSAGE=\"notice msg\"\n");
     buf_add_string(buffer, "LOG SEVERITY=info MESSAGE=\"info msg\"\n");
     buf_add_string(buffer, "LOG SEVERITY=debug MESSAGE=\"debug msg\"\n");
+  } else if (times_called <= 8) {
+    buf_add_string(buffer, "STATUS TYPE=a K_1=a K_2=b K_3=\"foo bar\"\n");
+    buf_add_string(buffer, "STATUS TYPE=b K_1=a K_2=b K_3=\"foo bar\"\n");
+    buf_add_string(buffer, "STATUS TYPE=c K_1=a K_2=b K_3=\"foo bar\"\n");
   }
 
   return (int)buf_datalen(buffer);
@@ -440,6 +444,23 @@ test_pt_configure_proxy(void *arg)
             "650 PT_LOG PT=<testcase> SEVERITY=debug "
             "MESSAGE=\"debug msg\"\r\n");
 
+  /* Get the STATUS messages out. */
+  process_notify_event_stdout(mp->process);
+
+  tt_int_op(controlevent_n, OP_EQ, 13);
+  tt_int_op(controlevent_event, OP_EQ, EVENT_PT_STATUS);
+  tt_int_op(smartlist_len(controlevent_msgs), OP_EQ, 13);
+
+  tt_str_op(smartlist_get(controlevent_msgs, 10), OP_EQ,
+            "650 PT_STATUS "
+            "PT=<testcase> TYPE=a K_1=a K_2=b K_3=\"foo bar\"\r\n");
+  tt_str_op(smartlist_get(controlevent_msgs, 11), OP_EQ,
+            "650 PT_STATUS "
+            "PT=<testcase> TYPE=b K_1=a K_2=b K_3=\"foo bar\"\r\n");
+  tt_str_op(smartlist_get(controlevent_msgs, 12), OP_EQ,
+            "650 PT_STATUS "
+            "PT=<testcase> TYPE=c K_1=a K_2=b K_3=\"foo bar\"\r\n");
+
   { /* check that the transport info were saved properly in the tor state */
     config_line_t *transport_in_state = NULL;
     smartlist_t *transport_info_sl = smartlist_new();